CN112029717A

CN112029717A - Serum-free in vitro domestication culture of human mesenchymal stem cells

Info

Publication number: CN112029717A
Application number: CN202010980495.4A
Authority: CN
Inventors: 许晓椿; 肖海蓉; 魏卿; 刘庆喜
Original assignee: Sinica Ltd
Current assignee: Shenzhen Boya Perception Pharmaceutical Co ltd
Priority date: 2020-09-17
Filing date: 2020-09-17
Publication date: 2020-12-04
Anticipated expiration: 2040-09-17
Also published as: CN112029717B

Abstract

The invention relates to a serum-free in-vitro domestication culture method for human mesenchymal stem cells. In one aspect, the acclimatization medium for serum-free in vitro acclimatization culture of human mesenchymal stem cells according to the present invention comprises: 8-12 ng/mL of transferrin, 8-12 ng/mL of insulin, 0-9.5% of fetal bovine serum and a balanced DMEM/F12 culture medium. In another aspect, the invention relates to a method for serum-free acclimation culture of mesenchymal stem cells, comprising the steps of: collecting Wharton's jelly, culturing in MSC complete culture medium, and digesting with trypsin solution to obtain cell precipitate as P0 generation cell; then culturing the cells by using an MSC (mesenchymal Stem cell) acclimation culture medium containing less than 10% fetal calf serum, digesting the cells by using a trypsin solution to obtain P1 generation cells, and treating the cells obtained in the last step in the operation process by using the MSC acclimation culture medium which sequentially reduces the fetal calf serum concentration to be 0% finally to obtain the final serum-free in-vitro acclimation cultured mesenchymal Stem cells. The method of the invention exhibits the excellent effects described in the specification.

Description

Serum-free in vitro domestication culture of human mesenchymal stem cells

Technical Field

The invention belongs to the fields of biotechnology and biomedicine, and relates to a culture method of human mesenchymal stem cells, in particular to a method for serum-free in-vitro domestication culture of human mesenchymal stem cells.

Background

Mesenchymal Stem Cells (MSCs), such as human mesenchymal stem cells, were first isolated from bone marrow and a class of tissue stem cells derived from the mesoderm, which have the potential for multipotent differentiation and the ability to self-renew, have the ability to differentiate into various adult cells, such as osteoblasts, chondrocytes, adipocytes, endothelial cells, nerve cells, muscle cells, hepatocytes, etc., under specific conditions in vivo and in vitro (Cap AI. mesenchymal stem cells. J Orthop Res.1991,9:641-650.Pittenger MF, Mackay AM, Beck, et al. multilineage patent of epithelial man stem cells. science.1999; 284:143 Across 147). Recent research shows that the mesenchymal stem cells have the functions of immunoregulation and hematopoietic support, and are easy to introduce and express exogenous genes. Therefore, the mesenchymal stem cells are not only seed cells in the construction of tissue engineering bone, cartilage and cardiac muscle and important carrier cells in gene therapy, but also have wide application prospect in hematopoietic stem cell transplantation and organ transplantation because the mesenchymal stem cells promote hematopoietic reconstruction and inhibit graft-versus-host reaction. Mesenchymal stem cells have the characteristic of adherent growth in vitro, and by utilizing the characteristic, the mesenchymal stem cells are successfully separated and cultured from various tissues such as liver, kidney, pancreas, muscle, cartilage, skin, peripheral blood and the like.

At present, the reported mesenchymal stem cells are mainly derived from bone marrow and are obtained by adopting a density gradient centrifugation method. Although the separation method is simple, the donor needs to undergo a painful operation for taking marrow, and has a high infection chance in and after the material is taken; because the content of MSC in human bone marrow is very rare, every 10⁵～10⁶Only about 1 of the mononuclear cells are present, and the number, proliferation and differentiation capacity of mesenchymal stem cells in the bone marrow are remarkably reduced with the increase of the age, so that the research and application, particularly the clinical application of the mesenchymal stem cells are limited. The placenta, which originates from the extraembryonic mesoderm during the embryonic development, is composed of mesenchyme, blood vessels and trophoblasts, and contains a large amount of mesenchyme components. Recent research shows that the placenta contains abundant stem cells, and the separation and culture of the pluripotent stem cells from the placenta opens up a brand-new and abundant source for experimental research and clinical application.

There are many reports in the literature on the establishment of a placental stem cell bank by isolating stem cells from placenta, such as the invention entitled "placental mesenchymal stem cell isolation and in vitro expansion culture method" disclosed in CN101270349A (chinese patent application No. 200810061267.6, published as 2008/9/24); CN101693884A (chinese patent application No. 200910117522.9, published 2010, 4 months and 14 days) entitled "a method for separating and extracting stem cells from placenta, umbilical cord or adipose tissue"; CN102146359A (chinese patent application No. 201110005964.1, published 2011/8/10) discloses an invention entitled "method for extracting original mesenchymal stem cells from placenta and serum-free expansion". In addition, chinese patent application No. 201210044648X discloses a method of isolating mesenchymal stem cells from placenta.

Stem cells are progenitors of human cells, and all cells in our body are derived from stem cells. When cells in the body age, die or the lesion denatures, stem cells grow and transform out of cells that can replace them. As seed cells, the compound is mainly used for treating various refractory diseases of tissue cells and organ injuries which cannot be naturally repaired by an organism clinically; as immunoregulatory cells, for the treatment of immune rejection and autoimmune diseases. Human mesenchymal stem cells are important members of a stem cell family, are derived from mesoderm in early development and belong to pluripotent stem cells, and are discovered in bone marrow initially, so that the human mesenchymal stem cells are increasingly concerned because of the characteristics of multidirectional differentiation potential, hematopoietic support, stem cell implantation promotion, immune regulation, self-replication and the like. Initial clinical studies were conducted in 1995 by Lazarus et al, who collected autologous MSCs of patients with hematological tumors in remission, cultured for 4-7 weeks in vitro for expansion, and then injected intravenously into patients, who were divided into 3 groups, administered different doses of MSCs, respectively, and no toxic side effects were observed after injection, suggesting that MSCs are safe and reliable for transplantation therapy. Then, clinical reports of autologous MSC are gradually increased, and the disease types comprise hematopoietic reconstruction after radiotherapy and chemotherapy, graft-versus-host disease (GVHD), heart system diseases and the like, and clinical intravenous infusion is proved to be safe and reliable in the reports.

The in vitro culture process of mesenchymal stem cells is a key step related to the use safety of stem cells as therapeutic drugs. The composition of the culture process, in particular of the culture medium, is a major influencing parameter. In the methods described in the prior documents, when the mesenchymal stem cells are cultured and passaged, serum such as fetal bovine serum is added to the culture medium, in particular, 10% of fetal bovine serum is usually added, and for example, the mesenchymal stem cells are cultured and passaged by using an MSC complete culture medium (which is DMEM/F12 medium containing 10% of fetal bovine serum).

On the one hand, however, the cost of fetal bovine serum is rather high, which is disadvantageous for the culture of mesenchymal stem cells; on the other hand, the presence of fetal bovine serum as an exogenous material of animal origin in stem cells poses a potential risk to the safety of clinical use of the cells. Therefore, it is meaningful to culture mesenchymal stem cells without serum acclimation.

CN108642002A (201810047983.2) discloses a method for serum-free domestication culture of human mesenchymal stem cells. The method uses a fresh serum-free basal culture medium, adds and replaces serum-containing complete culture solution of in vitro human mesenchymal stem cells according to a certain proportion, and uses exosome and microcapsule components secreted by the mesenchymal stem cells in the culture process as supplements to enable the mesenchymal stem cells to finish the acclimation of serum-free culture, thereby finally realizing a serum-free culture system. The density and the activity rate of the domesticated mesenchymal stem cells and the main markers on the cell surface have no obvious difference with a serum culture medium, and the components and the abundance of cytokines secreted by a culture solution and exosomes are detected to find that the expression quantity of bFGF, PDGF and VEGF related to the growth of blood vessels is improved compared with that of the domesticated cells. However, since the CN108642002a method is to culture cells directly in serum-free medium, the nutrition of the cell environment is reduced dramatically, and many adverse effects are caused to the cells.

Therefore, it is still expected to provide a new method for culturing mesenchymal stem cells, and in particular, a new method for serum-free in vitro acclimation culture of human mesenchymal stem cells.

Disclosure of Invention

The invention aims to provide a unique culture method aiming at the defects in the prior art, and provides a serum-free domestication culture method for in vitro culture of human mesenchymal stem cells. The purpose of the invention is realized by the following technical scheme.

In a first aspect of the present invention, there is provided a method for serum-free acclimation culture of mesenchymal stem cells, comprising the steps of:

(1) the placenta surface was washed with tissue washes to remove surface congestion, the umbilical cord was trimmed and the internal blood vessels were removed.

(2) Stripping Wharton's jelly in umbilical cord, cleaning, and shearing into 2-3mm pieces³Transferred to T75 flasks at 1mL per flask.

(3) Add slowly 10mL of MSC complete medium to the flask, gently shake the flask to allow the umbilical cord tissue pieces to lay flat in the flask, 5% CO at 37 deg.C₂And (3) carrying out static culture in an incubator, supplementing liquid once every 2-3 days, and supplementing liquid for 2-3 times, removing tissue blocks, replacing a total amount of MSC complete culture medium, and continuing to culture until the cell grows to 70% of fusion degree, and then digesting the obtained cell.

(4) The culture medium in the culture bottle is sucked and discarded, PBS is sucked to rinse the culture bottle to remove residual fetal calf serum, 3mL of 0.25% trypsin solution is added for digestion, the culture bottle is tapped to enable cells to fall to the bottom of the culture bottle, 10mL of MSC complete culture medium is added to neutralize the trypsin so as to stop the digestion process, a liquid transfer machine is used for blowing off the cells, cell suspension is collected in a centrifuge tube, centrifugation is carried out, supernatant is discarded, and cells with cell sediment marked as P0 generation are obtained.

(5) The P0 cell pellet was resuspended in 10mL of MSC acclimation medium containing less than 10% fetal bovine serum, the cells were counted, and then the cell count was 1X 10 according to the inoculation density⁴Individual MSC cells/cm²Inoculating into T75 culture bottle, supplementing the above MSC acclimatization culture medium to 10mL, and culturing at 37 deg.C with 5% CO₂Standing and culturing for more than 72h in an incubator until the cell fusion degree reaches 80%, sucking the culture medium in the culture bottle, sucking PBS to rinse the culture bottle to remove residual fetal calf serum, adding 3mL of 0.25% trypsin solution for digestion, tapping the culture bottle to make the cells fall to the bottom of the culture bottle, adding 10mL of MSC acclimation culture medium used in the step to add the cells into the trypsinAnd blowing off the cells by using a pipette to terminate the digestion process, collecting the cell suspension in a centrifugal tube, centrifuging, and removing the supernatant to obtain a cell precipitate which is marked as P1 generation cells.

(6) And (5) treating the cells obtained in the previous step in the operation process by using the MSC acclimation culture medium for sequentially reducing the concentration of fetal calf serum to be 0% finally by adopting the culture and digestion method in the step (5) to obtain the final serum-free mesenchymal stem cells subjected to in vitro acclimation culture. Optionally (c) is

(7) And (4) continuously culturing and passaging the mesenchymal stem cells of the last generation obtained in the last step by using an MSC (mesenchymal stem cell) acclimation culture medium containing 0% fetal calf serum (so as to continuously transfer to the mesenchymal stem cells of the P20 generation cultured in the serum-free acclimation culture).

The method according to the first aspect of the invention, wherein the tissue wash is a 0.9% physiological saline solution containing 1% penicillin and 1% streptomycin.

The method according to the first aspect of the present invention, wherein the gordonia gel is washed with the tissue washing solution in the step (2).

The method according to the first aspect of the present invention, wherein the MSC complete medium is DMEM/F12 medium containing 10% fetal bovine serum.

The method according to the first aspect of the present invention, wherein in step (3), 3 to 4mL of the MSC complete medium is supplemented every 2 to 3 days.

The method according to the first aspect of the present invention, wherein in step (4), after adding the trypsin solution, the culture flask is gently shaken to allow the trypsin to sufficiently cover the cell surface, the cells are digested for 1min until the cells are microscopically observed to shrink into a round shape, and the culture flask is gently tapped to allow the cells to fall off in a stream of sands to the bottom of the culture flask.

The method according to the first aspect of the present invention, wherein in step (4), the mixture is centrifuged at 1400rpm for 5min in a centrifuge.

The method according to the first aspect of the present invention, wherein in the step (5), the P0 generation cell pellet is resuspended in MSC acclimation medium containing 7-9.5% fetal bovine serum.

The method according to the first aspect of the present invention, wherein in step (5), the cell pellet of P0 generation is resuspended in MSC acclimation medium containing 8-9.5% fetal bovine serum, for example, 8%, 8.5%, 9%, or 9.5% fetal bovine serum.

The method according to the first aspect of the present invention, wherein in the repeating of step (5) in step (6), the concentration of fetal bovine serum in the MSC acclimation medium decreases as the number of generations increases until the concentration of fetal bovine serum in the MSC acclimation medium is 0.

According to the method of the first aspect of the invention, in the step (6), the serum-free mesenchymal stem cells cultured in vitro are obtained by gradually reducing the concentration of the fetal calf serum until the generation of P4-P10.

According to the method of the first aspect of the invention, in the step (6), the serum-free mesenchymal stem cells cultured in vitro are obtained by gradually reducing the concentration of the fetal calf serum until the generation of P4-P9.

According to the method of the first aspect of the invention, in the step (6), the serum-free mesenchymal stem cells cultured in vitro are obtained by gradually reducing the concentration of the fetal calf serum until the generation of P4-P8.

According to the method of the first aspect of the invention, in the step (7), the mesenchymal stem cells cultured by the in vitro domestication of 0% fetal serum finally obtained in the step (6) are continuously cultured and passaged by the domestication culture medium containing 0% fetal bovine serum MSC, and are continuously transferred to the mesenchymal stem cells of the generation P20 which are cultured by the serum-free domestication culture.

The method according to the first aspect of the present invention, wherein the MSC acclimation medium comprises: 8-12 ng/mL of transferrin, 8-12 ng/mL of insulin, 0-9.5% of fetal bovine serum and a balanced DMEM/F12 culture medium.

The method according to the first aspect of the present invention, wherein the MSC acclimation medium comprises: 10ng/mL of transferrin, 10ng/mL of insulin, 0-9.5% of fetal bovine serum and a balanced DMEM/F12 culture medium.

The method according to the first aspect of the present invention, wherein the MSC acclimation medium further comprises 3- (2-methoxyphenoxy) -1, 2-propanediol and magnesium chloride. In one embodiment, the concentration of 3- (2-methoxyphenoxy) -1, 2-propanediol is 0.08-0.12 mg/mL. In one embodiment, the magnesium chloride is present in a concentration of 4-6 μ g/mL magnesium ions. In one embodiment, the concentration of 3- (2-methoxyphenoxy) -1, 2-propanediol is 0.1 mg/mL. In one embodiment, the magnesium chloride is 5 μ g/mL in magnesium ion concentration. 3- (2-methoxyphenoxy) -1, 2-propanediol, also known as guaifenesin, having CAS registry number 93-14-1.

The method according to the first aspect of the present invention, wherein the MSC acclimation medium comprises: 8-12 ng/mL of transferrin, 8-12 ng/mL of insulin, 0.08-0.12 mg/mL of 3- (2-methoxyphenoxy) -1, 2-propylene glycol, 4-6 mu g/mL of magnesium chloride in terms of magnesium ion concentration, 0-9.5% of fetal bovine serum and a balanced DMEM/F12 culture medium. The method according to the first aspect of the present invention, wherein the MSC acclimation medium comprises: 10ng/mL of transferrin, 10ng/mL of insulin, 0.1mg/mL of 3- (2-methoxyphenoxy) -1, 2-propylene glycol, 5 mu g/mL of magnesium chloride in terms of magnesium ion concentration, 0-9.5% of fetal calf serum and a balanced DMEM/F12 culture medium. In the present invention, the term "equilibrium amount" means an amount added to the total amount, which herein means adding the rest of the substances to their respective prescribed concentrations on the basis of DMEM/F12 medium, unless otherwise specified.

Further, the second aspect of the present invention relates to a acclimatization medium for serum-free in vitro acclimatization culture of human mesenchymal stem cells, comprising: 8-12 ng/mL of transferrin, 8-12 ng/mL of insulin, 0-9.5% of fetal bovine serum and a balanced DMEM/F12 culture medium.

The acclimatisation medium according to the second aspect of the invention, comprising: 10ng/mL of transferrin, 10ng/mL of insulin, 0-9.5% of fetal bovine serum and a balanced DMEM/F12 culture medium.

The acclimatization medium according to the second aspect of the invention, further comprising 3- (2-methoxyphenoxy) -1, 2-propanediol and magnesium chloride. In one embodiment, the concentration of 3- (2-methoxyphenoxy) -1, 2-propanediol is 0.08-0.12 mg/mL. In one embodiment, the magnesium chloride is present in a concentration of 4-6 μ g/mL magnesium ions. In one embodiment, the concentration of 3- (2-methoxyphenoxy) -1, 2-propanediol is 0.1 mg/mL. In one embodiment, the magnesium chloride is 5 μ g/mL in magnesium ion concentration. 3- (2-methoxyphenoxy) -1, 2-propanediol, also known as guaifenesin, having CAS registry number 93-14-1.

The acclimatisation medium according to the second aspect of the invention, comprising: 8-12 ng/mL of transferrin, 8-12 ng/mL of insulin, 0.08-0.12 mg/mL of 3- (2-methoxyphenoxy) -1, 2-propylene glycol, 4-6 mu g/mL of magnesium chloride in terms of magnesium ion concentration, 0-9.5% of fetal bovine serum and a balanced DMEM/F12 culture medium.

The acclimatisation medium according to the second aspect of the invention, comprising: 10ng/mL of transferrin, 10ng/mL of insulin, 0.1mg/mL of 3- (2-methoxyphenoxy) -1, 2-propylene glycol, 5 mu g/mL of magnesium chloride in terms of magnesium ion concentration, 0-9.5% of fetal calf serum and a balanced DMEM/F12 culture medium. In the present invention, the term "equilibrium amount" means an amount added to the total amount, which herein means adding the rest of the substances to their respective prescribed concentrations on the basis of DMEM/F12 medium, unless otherwise specified.

The acclimatization culture medium according to the second aspect of the invention, wherein the serum-free in vitro acclimatization culture of human mesenchymal stem cells is carried out according to the following steps:

(5) The P0 cell pellet was resuspended in 10mL of MSC acclimation medium containing less than 10% fetal bovine serum, the cells were counted, and then the cell count was 1X 10 according to the inoculation density⁴Individual MSC cells/cm²Inoculating into T75 culture bottle, supplementing the above MSC acclimatization culture medium to 10mL, and culturing at 37 deg.C with 5% CO₂And (3) performing static culture in an incubator for more than 72 hours until the cell fusion degree reaches 80%, sucking the culture medium in the culture bottle, sucking PBS to rinse the culture bottle to remove residual fetal calf serum, adding 3mL of 0.25% trypsin solution for digestion, slightly tapping the culture bottle to enable the cells to fall to the bottom of the culture bottle, adding 10mL of MSC acclimation culture medium used in the step to neutralize the trypsin so as to terminate the digestion process, blowing off the cells by using a pipettor, collecting cell suspension in a centrifuge tube, centrifuging, and discarding supernatant to obtain cell sediment which is marked as P1 generation cells.

The acclimatization medium according to the second aspect of the invention, wherein the tissue washing solution is a 0.9% physiological saline solution containing 1% penicillin and 1% streptomycin.

The acclimatization medium according to the second aspect of the present invention, wherein the gordonia gum is washed with a tissue washing solution in step (2).

The acclimatization medium according to the second aspect of the present invention, wherein the MSC complete medium is DMEM/F12 medium containing 10% fetal bovine serum.

The acclimatization medium according to the second aspect of the present invention, wherein in step (3), 3-4mL of the MSC complete medium is supplemented every 2-3 days for fluid infusion.

The acclimatization medium according to the second aspect of the invention, wherein in the step (4), after adding the trypsin solution, the culture flask is gently shaken to make the trypsin sufficiently cover the cell surface, the cells are digested for 1min until the cells are microscopically observed to shrink into a round shape, and the culture flask is gently tapped to make the cells shed into a sandy shape to the bottom of the culture flask.

The acclimatization medium according to the second aspect of the present invention, wherein in step (4), the medium is centrifuged at 1400rpm for 5min in a centrifuge.

The acclimatization medium according to the second aspect of the invention, wherein in the step (5), the P0 generation cell sediment is resuspended in MSC acclimatization medium containing 7-9.5% fetal bovine serum.

The acclimatization medium according to the second aspect of the invention, wherein in the step (5), the cell pellet of P0 generation is resuspended in MSC acclimatization medium containing 8-9.5% fetal bovine serum, for example, 8%, 8.5%, 9%, or 9.5% fetal bovine serum.

The acclimatization medium according to the second aspect of the present invention, wherein in the process of repeating the step (5) in the step (6), the concentration of fetal calf serum in the MSC acclimatization medium decreases with the increase of the generation number of the cells until the concentration of fetal calf serum in the MSC acclimatization medium is 0.

The domestication culture medium according to the second aspect of the invention, wherein in the step (6), the serum-free mesenchymal stem cells cultured in vitro are obtained by gradually reducing the concentration of fetal calf serum until the generation of P4-P10.

The domestication culture medium according to the second aspect of the invention, wherein in the step (6), the serum-free mesenchymal stem cells cultured in vitro are obtained by gradually reducing the concentration of fetal calf serum until the generation of P4-P9.

The domestication culture medium according to the second aspect of the invention, wherein in the step (6), the serum-free mesenchymal stem cells cultured in vitro are obtained by gradually reducing the concentration of fetal calf serum until the generation of P4-P8.

The domestication culture medium according to the second aspect of the invention, wherein in the step (7), the mesenchymal stem cells obtained by the in vitro domestication culture of 0% fetal serum finally obtained in the step (6) are continuously cultured and passaged by using the domestication culture medium containing 0% fetal bovine serum MSC, and are continuously transferred to the mesenchymal stem cells of P20 generation which are subjected to serum-free domestication culture.

Of the various process steps described in this invention, those skilled in the art can, however, readily generalize the above-described process steps from the detailed disclosure throughout the present invention, even though the specific steps described therein may differ in some detail or in language specific to the steps described in the preparation examples of the detailed description section below.

Any embodiment of any aspect of the present invention may be combined with any other embodiment, as long as they do not contradict each other. Furthermore, in any embodiment of any aspect of the invention, any feature may be applicable to that feature in other embodiments, so long as they do not contradict. The invention is further described below.

All documents cited herein are incorporated by reference in their entirety and to the extent such documents do not conform to the meaning of the present invention, the present invention shall control. Further, the various terms and phrases used herein have the ordinary meaning as is known to those skilled in the art, and even though such terms and phrases are intended to be described or explained in greater detail herein, reference is made to the term and phrase as being inconsistent with the known meaning and meaning as is accorded to such meaning throughout this disclosure.

It is well known that MSC are abundant in origin, mainly organized in perinatal: placenta, umbilical cord, amnion, amniotic fluid, etc. Especially, the MSC from the umbilical cord is more convenient to prepare and has high quality. The umbilical cord comprises a vein and two arteries, wherein Wharton's jelly is arranged around the veins, the outer layer of the umbilical cord is wrapped by the epithelium from the source of amnion, and from the development perspective, the umbilical cord is a passage for forming and passing stem cells, and the research shows that the connective tissue of the human umbilical cord is a tissue source rich in mesenchymal stem cells. The treatment method comprises the steps of firstly stripping umbilical cord arteriovenous and outer epithelium to leave gelatinous tissue (Wharton's jelly), and cutting off the part with clamping marks and extravasated blood on both sides.

The method for serum-free in-vitro domestication culture of the human mesenchymal stem cells, provided by the invention, has the advantages that the prepared mesenchymal stem cells have excellent technical effects in one or more aspects as described herein.

Drawings

FIG. 1: as a result of osteogenic induced differentiation, a is a serum-free acclimation experimental group (the dark part in the original photograph is orange red), and b is a control group.

FIG. 2: the adipogenic induced differentiation results are shown in a serum-free domestication experimental group (the dark part in the original picture is red) and b a control group.

FIG. 3: chondrogenic induced differentiation results, a serum-free acclimation experimental group (dark blue part in the middle of original photograph, b control group).

FIG. 4: flow cytophenotype results (from top to bottom, CD73, CD90, CD105, HLA-DR, left panel for serum-free acclimation group, right panel for conventional culture group).

Detailed Description

The present invention will be further described by the following examples, however, the scope of the present invention is not limited to the following examples. It will be understood by those skilled in the art that various changes and modifications may be made to the invention without departing from the spirit and scope of the invention. The present invention has been described generally and/or specifically with respect to materials used in testing and testing methods. The following provides specific materials and sources thereof used in embodiments of the present invention. However, it should be understood that these are exemplary only and not intended to limit the invention, and that materials of the same or similar type, quality, nature or function as the following reagents and instruments may be used in the practice of the invention. The experimental procedures used in the following examples are all conventional procedures unless otherwise specified. Materials, reagents and the like used in the following examples are commercially available unless otherwise specified.

All percentages used in the present invention are by weight unless otherwise indicated. In this context, reference to PBS buffer or PBS solution or PBS, etc., unless otherwise specified, refers to phosphate buffer at pH6.8, which is prepared by: 250mL of 0.2mol/L potassium dihydrogen phosphate solution is taken, 118mL of 0.2mol/L sodium hydroxide solution is added, the solution is diluted to 1000mL by water, and the mixture is shaken up to obtain the potassium dihydrogen phosphate.

Preparation of MSC complete medium: adding fetal calf serum into DMEM/F12 culture medium to reach concentration of 10%.

Preparation of MSC acclimatization medium (also called reduced serum medium): to DMEM/F12 medium, Transferrin (to a concentration of 10ng/mL, from Transferrin, ProSpec-Tany Co., Ltd.), insulin (to a concentration of 10ng/mL, from Sigma-Aldrich Co., Ltd.), fetal bovine serum (to a concentration of 0 to 9.5%, for example, to a concentration of 9.5%, 9%, 8%, 7.5%, 7%, 6%, 5.5%, 5%, 4%, 3%, 2%, 1%, 0%, etc., from Gibco Co., Ltd.) was added to prepare MSC acclimation medium containing Transferrin, insulin and fetal bovine serum at various concentrations.

First, preparation of mesenchymal Stem cells

Example 1: serum-free domesticated culture MSC

(1) The surface of the placenta was washed with tissue washing solution (0.9% physiological saline containing 1% penicillin, 1% streptomycin) to remove surface congestion, the umbilical cord was cut and the internal blood vessels were removed.

The present embodiment specifically operates as follows: in the biosafety cabinet, a stainless steel tray, a filter screen, a stainless steel cup, a lunch box, a tissue cleaning fluid (0.9% physiological saline containing 1% penicillin and 1% streptomycin), a pipettor and the like are put at proper positions. The placenta tissue is taken out by using a surgical forceps and is placed in a stainless steel tray, and the surface of the placenta is cleaned by using a tissue cleaning solution to remove the extravasated blood on the surface of the placenta. The umbilical cord at the connection with the placenta is cut off by using surgical scissors and forceps, and the other end of the umbilical cord is cut off from the back of the umbilical cord sterile clamp. The umbilical cord was removed and washed 3 times with tissue washes to remove surface clots and clots. One end of the cord is grasped with forceps and the cord is grasped with another forceps and slid along the cord tissue to remove residual cord blood from the blood vessels. The umbilical cord is cut into several sections with the length of 2-3cm, then the umbilical cord is cut open along the longitudinal section of the umbilical cord by scissors, and the umbilical cord is flattened to remove 3 blood vessels (2 umbilical arteries and 1 umbilical vein) inside the umbilical cord. Transfer to a new plate.

(2) Stripping Wharton's jelly in umbilical cord, cleaning with tissue cleaning solution, and shearing into 2-3mm pieces³Transferred to T75 flasks at 1mL per flask.

The present embodiment specifically operates as follows: stripping the Wharton's jelly with forceps, placing into a culture dish filled with a tissue washing solution, washing with the tissue washing solution, and tearing the Wharton's jelly into strips. Transferring the Wharton's jelly into a 50mL centrifuge tube by using forceps after the treatment is finished, and shearing the Wharton's jelly to 2-3mm by using scissors³The small pieces were transferred to T75 culture flasks at 1mL per flask using a 3mL sterile dropper, which had to be cut off with sterile scissors before use.

(3) To the flask, 10mL of MSC complete medium (DMEM/F12 medium containing 10% fetal bovine serum) was slowly added, and the flask was gently shaken to allow the umbilical cord tissue pieces to be spread in the flask, 5% CO at 37 deg.C₂And (3) carrying out static culture in an incubator, supplementing liquid once every 2-3 days (supplementing 3-4mL of MSC complete culture medium every time), removing tissue blocks and replacing the MSC complete culture medium in full quantity to continue culturing until the cell grows to reach 70% fusion degree after 2-3 times of total liquid supplementation, and then digesting the obtained cell.

The present embodiment specifically operates as follows: to the flask, 10mL of MSC complete medium (DMEM/F12 medium containing 10% fetal bovine serum) was slowly added, and the flask was gently shaken to allow the umbilical cord tissue pieces to be spread in the flask. Placing the T75 culture flask at 37 deg.C with 5% CO₂And (5) standing and culturing in an incubator. The flasks were removed from the incubator by the third day of culture, supplemented with 3.5mL of MSC complete medium, and replenished once every 3 days thereafter. After 3 times of fluid replacement, cells at the bottom of the culture flask climbed out, the tissue blocks were removed and the complete culture medium of MSC was replaced in full for further culture. After the cells grow to be fusedWhen the degree of integration reached 70%, the cells obtained were then digested.

(4) The medium in the flask was discarded by aspiration, the flask was rinsed with PBS (20 mL) to remove residual fetal bovine serum, 3mL of 0.25% trypsin solution was added for digestion, the flask was tapped to detach the cells to the bottom of the flask, 10mL of MSC complete medium was added to neutralize trypsin to stop the digestion process, the cells were blown off by a pipette, the cell suspension was collected in a centrifuge tube, centrifuged, and the supernatant was discarded to obtain the cell pellet marked as P0 passage.

The present embodiment specifically operates as follows: prior to cell subculture, 0.25% trypsin, MSC complete medium (DMEM/F12 medium containing 10% fetal bovine serum), PBS were placed at room temperature at equilibrium temperature. The culture flask was taken out of the incubator, the medium in the flask was removed by pipetting, and the flask was rinsed with 20mL of PBS to remove residual fetal bovine serum. Adding 3mL of 0.25% trypsin solution into a culture bottle for digestion, slightly shaking the culture bottle to enable the trypsin to fully cover the cell surface, digesting for about 1min, observing the cells to shrink into a circle under a microscope, slightly beating the culture bottle to enable the cells to shed to the bottom of the culture bottle in a flowing sand shape, adding 10mL of MSC complete culture medium to neutralize the trypsin to stop the digestion process, blowing off the cells by using a pipettor, and collecting cell suspension in a 15mL centrifuge tube. The tube was placed in a centrifuge and centrifuged at 1400rpm for 5min to remove the supernatant and the pellet was scored as P0 passages.

(5) The P0 cell pellet was resuspended in 10mL of MSC acclimatization medium containing 9% fetal calf serum, cell counting was performed, and then the cell pellet was resuspended at an inoculation density of 1X 10⁴Individual MSC cells/cm²Inoculating into T75 culture bottle, supplementing the above MSC acclimatization culture medium to 10mL, and culturing at 37 deg.C with 5% CO₂Standing in an incubator for over 72h until the cell fusion degree reaches 80%, sucking the culture medium in a culture bottle, sucking (20 mL) PBS to rinse the culture bottle to remove residual fetal calf serum, adding 3mL of 0.25% trypsin solution for digestion, tapping the culture bottle to make the cells fall to the bottom of the culture bottle, adding 10mL of MSC acclimation culture medium used in the step to neutralize the trypsin so as to terminate the digestion process, and blowing off the cells by using a pipetteAnd collecting the cell suspension in a centrifuge tube, centrifuging, and discarding the supernatant to obtain a cell precipitate which is marked as P1 generation cells.

(6) The method of culture and digestion in the step (5) is adopted, the cells obtained in the last step in the operation process are treated by MSC domestication culture medium which reduces the concentration of fetal calf serum to 0% in turn to obtain the final serum-free mesenchymal stem cells cultured in vitro (in the embodiment, culture and digestion are carried out on P1 generation cells by using MSC domestication culture medium containing 7.5% fetal calf serum (obtaining P2 generation cells), culture and digestion are carried out on P2 generation cells by using MSC domestication culture medium containing 5.5% fetal calf serum (obtaining P3 generation cells), culture and digestion are carried out on P3 generation cells by using MSC domestication culture medium containing 3% fetal calf serum (obtaining P4 generation cells), culture and digestion are carried out on P4 generation cells by using MSC domestication culture medium containing 0% fetal calf serum (obtaining P5 generation cells), and the harvested P5 generation cells can be subjected to subsequent detection or used for serum-free culture, Passage). Optionally (c) is

In the present embodiment, the first and second electrodes are,

culturing with MSC complete culture medium (containing 10% fetal calf serum) to obtain P0 generation cells,

culturing with reduced serum culture medium (containing transferrin, insulin, 9% fetal calf serum) to obtain P1 generation cells,

culturing with reduced serum culture medium (containing transferrin, insulin, 7.5% fetal calf serum) to obtain P2 generation cells,

culturing with reduced serum culture medium (containing transferrin, insulin, 5.5% fetal calf serum) to obtain P3 generation cells,

culturing with reduced serum culture medium (containing transferrin, insulin, and 3% fetal calf serum) to obtain P4 generation cells,

culturing in serum-free culture medium (containing transferrin, insulin and 0% fetal calf serum) to obtain P5 generation cells; in various assays subsequent to the present invention, the generation of cells (which are also referred to as test cells) is performed, if not otherwise stated.

The reduced serum medium or MSC acclimation medium described in this example, e.g., reduced serum medium for obtaining P1 generation cells, was formulated as follows: adding transferrin (to a concentration of 10ng/mL), insulin (to a concentration of 10ng/mL) and fetal calf serum (to a concentration of 9%) into a DMEM/F12 culture medium to prepare MSC acclimation culture media containing transferrin, insulin and fetal calf serum with different concentrations; in other words, the reduced serum medium used to obtain the P1 generation cells of this example contained: 10ng/mL of transferrin, 10ng/mL of insulin, 9% of fetal bovine serum and balance DMEM/F12 culture medium. In the present invention, reduced serum medium or MSC acclimation medium has similar meaning unless otherwise stated.

Example 2: serum-free domesticated culture MSC

In the same manner as in example 1, the cell pellets in steps (1) to (4) were obtained as cells of P0 passage.

Steps (5) to (6) were conducted in accordance with the procedures in example 1 except that the gradient change of the decrease in fetal bovine serum concentration in the MSC acclimation medium was used. Optionally (c) is

In the present embodiment, the first and second electrodes are,

culturing with reduced serum culture medium (containing transferrin, insulin, 7% fetal calf serum) to obtain P2 generation cells,

culturing with reduced serum culture medium (containing transferrin, insulin, and 5% fetal calf serum) to obtain P3 generation cells,

Example 3: serum-free domesticated culture MSC

(7) And (4) continuously culturing and passaging the mesenchymal stem cells of the last generation obtained in the last step by using an MSC (mesenchymal stem cell) acclimation culture medium containing 0% fetal calf serum (so as to continuously transfer to the mesenchymal stem cells of the P18 generation cultured in the serum-free acclimation culture).

In the present embodiment, the first and second electrodes are,

culturing with reduced serum culture medium (containing transferrin, insulin, and 8% fetal calf serum) to obtain P2 generation cells,

culturing with reduced serum culture medium (containing transferrin, insulin, 6% fetal calf serum) to obtain P3 generation cells,

culturing with reduced serum culture medium (containing transferrin, insulin, 4% fetal calf serum) to obtain P4 generation cells,

culturing with reduced serum culture medium (containing transferrin, insulin, 2% fetal calf serum) to obtain P5 generation cells,

culturing in serum-free culture medium (containing transferrin, insulin and 0% fetal calf serum) to obtain P6 generation cells; in various assays subsequent to the present invention, the generation of cells (which are also referred to as test cells) is performed, if not otherwise stated.

Example 4: serum-free domesticated culture MSC

In the present embodiment, the first and second electrodes are,

culturing with reduced serum culture medium (containing transferrin, insulin, 9.5% fetal calf serum) to obtain P1 generation cells,

culturing with reduced serum culture medium (containing transferrin, insulin, and 8.5% fetal calf serum) to obtain P2 generation cells,

culturing with reduced serum culture medium (containing transferrin, insulin, 7.5% fetal calf serum) to obtain P3 generation cells,

culturing with reduced serum culture medium (containing transferrin, insulin, 6% fetal calf serum) to obtain P4 generation cells,

culturing with reduced serum culture medium (containing transferrin, insulin, 4% fetal calf serum) to obtain P5 generation cells,

culturing with reduced serum culture medium (containing transferrin, insulin, 2% fetal calf serum) to obtain P6 generation cells,

culturing in serum-free culture medium (containing transferrin, insulin and 0% fetal calf serum) to obtain P7 generation cells; in various assays subsequent to the present invention, the generation of cells (which are also referred to as test cells) is performed, if not otherwise stated.

Example 5: serum-free domesticated culture MSC

(7) And (4) continuously culturing and passaging the mesenchymal stem cells of the last generation obtained in the last step by using an MSC (mesenchymal stem cell) acclimation culture medium containing 0% fetal calf serum (so as to continuously transfer to the mesenchymal stem cells of the P15 generation cultured in the serum-free acclimation culture).

In the present embodiment, the first and second electrodes are,

culturing with reduced serum culture medium (containing transferrin, insulin, and 8% fetal calf serum) to obtain P1 generation cells,

culturing with reduced serum culture medium (containing transferrin, insulin, 6% fetal calf serum) to obtain P2 generation cells,

culturing with reduced serum culture medium (containing transferrin, insulin, and 3% fetal calf serum) to obtain P3 generation cells,

culturing in serum-free culture medium (containing transferrin, insulin and 0% fetal calf serum) to obtain P4 generation cells; in various assays subsequent to the present invention, the generation of cells (which are also referred to as test cells) is performed, if not otherwise stated.

Example 6: serum-free domesticated culture MSC

In the present embodiment, the first and second electrodes are,

culturing with reduced serum culture medium (containing transferrin, insulin, 9% fetal calf serum) to obtain P2 generation cells,

culturing with reduced serum culture medium (containing transferrin, insulin, and 8.5% fetal calf serum) to obtain P3 generation cells,

culturing with reduced serum culture medium (containing transferrin, insulin, 7.5% fetal calf serum) to obtain P4 generation cells,

culturing with reduced serum culture medium (containing transferrin, insulin, 6% fetal calf serum) to obtain P5 generation cells,

culturing with reduced serum culture medium (containing transferrin, insulin, 4.5% fetal calf serum) to obtain P6 generation cells,

culturing with reduced serum culture medium (containing transferrin, insulin, 2.5% fetal calf serum) to obtain P7 generation cells,

culturing in serum-free culture medium (containing transferrin, insulin and 0% fetal calf serum) to obtain P8 generation cells; in various assays subsequent to the present invention, the generation of cells (which are also referred to as test cells) is performed, if not otherwise stated.

Example 7: serum-free domesticated culture MSC

Referring to the procedures of examples 1 to 6, respectively, except that 3- (2-methoxyphenoxy) -1, 2-propanediol (to a concentration of 0.1mg/mL in each MSC acclimation medium) and magnesium chloride (to a concentration of 5. mu.g/mL in each MSC acclimation medium) were additionally added to MSC acclimation media of various fetal bovine serum concentrations, to finally obtain 6 types of serum-free acclimation-cultured mesenchymal stem cells, which were referred to as the generation cells of examples 71 to 76, respectively; in the various detection tests which follow the present invention, the corresponding passage of cells (which are also referred to as detection cells) for detection in the working examples referred to is carried out, if not stated otherwise.

The reduced serum medium or MSC acclimation medium described in this example, for example, in reference example 1, the reduced serum medium for obtaining P1 generation cells was prepared as follows: adding transferrin (to a concentration of 10ng/mL), insulin (to a concentration of 10ng/mL), fetal calf serum (to a concentration of 9%), 3- (2-methoxyphenoxy) -1, 2-propanediol (to a concentration of 0.1mg/mL), and magnesium chloride (to a concentration of 5 μ g/mL) to a DMEM/F12 medium to prepare an MSC acclimation medium containing transferrin, insulin, 3- (2-methoxyphenoxy) -1, 2-propanediol), magnesium chloride, and fetal calf serum at different concentrations; in other words, the reduced serum medium used to obtain the P1 generation cells of this example with reference to example 1 contained: 10ng/mL of transferrin, 10ng/mL of insulin, 9% of fetal bovine serum, 0.1mg/mL of 3- (2-methoxyphenoxy) -1, 2-propanediol, 5 mu g/mL of magnesium chloride in terms of magnesium ions and balance DMEM/F12 culture medium. In the present invention, reduced serum medium or MSC acclimation medium has similar meaning unless otherwise stated.

Example 8: serum-free domesticated culture MSC

Referring to the procedures of examples 1 to 6, except that 3- (2-methoxyphenoxy) -1, 2-propanediol was additionally added to the MSC acclimation medium of each fetal bovine serum concentration (to a concentration of 0.1mg/mL in each MSC acclimation medium), 6 types of serum-free acclimation-cultured mesenchymal stem cells were finally obtained, which were referred to as the generation cells of examples 81 to 86, respectively; in the various detection tests which follow the present invention, the corresponding passage of cells (which are also referred to as detection cells) for detection in the working examples referred to is carried out, if not stated otherwise.

Example 9: serum-free domesticated culture MSC

Referring to the procedures of examples 1 to 6, except that magnesium chloride was additionally added to the MSC acclimation medium of each fetal bovine serum concentration (to a concentration of 5 μ g/mL of magnesium ions in each MSC acclimation medium), 6 types of serum-free acclimation-cultured mesenchymal stem cells were finally obtained, which were referred to as the generation cells of examples 91 to 96, respectively; in the various detection tests which follow the present invention, the corresponding passage of cells (which are also referred to as detection cells) for detection in the working examples referred to is carried out, if not stated otherwise.

Example 10: serum cultured MSC

In the steps (5) and (6) of example 1, all of the MSC acclimation media were replaced with MSC complete media, and cells were cultured and digested to obtain P5 generation cells as serum-cultured mesenchymal stem cells, which were used as control cells for detection.

Testing of mesenchymal stem cells

MSCs are pluripotent stem cells derived from early-developing mesoderm and having high self-renewal ability and multipotentiality, and can be differentiated into hepatocyte-like cells, fibroblasts, osteoblasts, chondrocytes, adipocytes, myoblasts, extraneural blastocysts, and the like. Therefore, differentiation experiments of osteogenic, adipogenic and chondrogenic of the MSC are mostly used in laboratories to verify the multidirectional differentiation potential of the cells, thereby reflecting the quality of the cells.

Test example 1: serum-free domesticated MSC cell osteogenic induced differentiation and staining experiment

First, inoculation and osteogenic induction culture

1. Preparing a high-sugar complete culture medium: adding 56mL of fetal calf serum into 500mL of high-glucose-DMEM medium to prepare a high-glucose DMEM medium containing 10% fetal calf serum;

2. the serum-free acclimated MSC cells in the logarithmic growth phase of P5 obtained in example 1 were collected, digested with 0.25% trypsin solution, and the flask was gently shaken to allow trypsin to spread on the bottom surface of the flask. Digesting for about 1min, observing cell shrinkage and clustering under a microscope, slightly beating the culture flask to make the cells shed to the bottom of the culture flask in a flowing sand shape, adding a complete culture medium with the same volume as that of trypsin to stop digestion, blowing off the cells by using a pipette, and collecting cell suspension in a 15mL centrifuge tube.

3. After centrifugation at 1400rpm for 5min, the supernatant was removed. Cells were resuspended in 10mL of complete medium and counted.

4. According to 6X 10⁴Inoculum density of/mL was inoculated into 24-well plates, 1mL per well, for a total of 4 wells. 1 well is a control well and 3 wells are experimentsAnd (4) a hole. Place the plates at 30 ℃ 5% CO₂Culturing in an incubator.

5. After the cell fusion rate reached 80%, the medium was washed away, 0.5mL of high-glucose DMEM complete medium containing 10% fetal bovine serum was added to the control wells, and 0.5mL of MSC osteogenesis induction medium was added to the other 3 experimental wells. The plates were replaced at 30 ℃ with 5% CO₂And continuing culturing in the incubator.

6. Changing the liquid every 2-3 days. When the culture medium is changed, the original culture medium in the hole is firstly sucked and discarded, then 0.5mL of the corresponding culture medium is added, and the induction time is 15-20 days.

Second, dyeing identification

1. The staining identification of the osteogenesis induced differentiation culture adopts a alizarin S staining method.

2. And (3) sample fixation treatment: the culture medium was carefully aspirated from the 24-well plate, and 400. mu.L of PBS buffer was added to each well to wash the cell surface. PBS wash was carefully aspirated off and 300. mu.L of BI's Fixation Solution was added to each well, covering the entire growth surface. Standing at room temperature for 30min, carefully absorbing and discarding the BI Fixation Solution, adding 300 mu L of BI wash I lotion into each hole, and cleaning the cell surface for 2-3 times.

3. Sample staining treatment: wash I wash was discarded and 300. mu.L of BI stabilizing Solution was added and the bottom was soaked uniformly. Staining for 30min at room temperature, carefully sucking out the stabilizing Solution of BI, adding 300 mu L of wash II of BI, and rinsing the cells for 2-3 times. Wash II was aspirated away, 300. mu.L of an infection Solution was added, and the cells were observed under a microscope and photographed (the differentiated cells were stained orange-red).

The results are shown in FIG. 1, in which a serum-free acclimation experimental group showed that the cells were stained in a typical orange color, and in FIG. 1 b control group cells were not stained in a typical orange color.

The results of examining 5 test cells of examples 2 to 6, 6 test cells of example 7, the test cell of example 81, and the test cell of example 91 by referring to the method of test example 1 showed that all of these cells were stained in a typical orange color.

Test example 2: serum-free acclimated MSC cell adipogenic induction fractionChemical and dyeing experiment

Firstly, preparing a solution reagent:

1. the experiments were started by placing trypsin, MSCgo additive Differentiation basic Medium, MSCgo additive SF, XF Supplement Mix I, MSCgo additive SF, XF Supplement Mix II in a 37 ℃ incubator and pre-heating.

2. Preparing a high-sugar complete culture medium: adding 56mL of fetal calf serum into 500mL of high-glucose-DMEM medium to prepare a high-glucose DMEM medium containing 10% fetal calf serum;

3. preparation of fat induction medium: the Supplement Mix I and Supplement Mix II were pipetted into the MSCgo additive Differentiation basic Medium.

4. The serum-free acclimated MSC cells in the logarithmic growth phase of P5 obtained in example 1 were digested with trypsin, and the flask was gently shaken to allow the trypsin to spread on the bottom surface of the flask. Digesting for about 1min, observing cell shrinkage and clustering under a microscope, slightly beating the culture flask to make the cells shed to the bottom of the culture flask in a flowing sand shape, adding a complete culture medium with the same volume as that of trypsin to stop digestion, blowing off the cells by using a pipette, and collecting cell suspension in a 15mL centrifuge tube.

5. After centrifugation at 1400rpm for 5min, the supernatant was removed. Cells were resuspended in 10mL of complete medium and counted.

6. According to 6X 10⁴Inoculum density of/mL was inoculated into 24-well plates, 1mL per well, for a total of 4 wells. 1 well is a control well and 3 wells are experimental wells. Place the plates at 30 ℃ 5% CO₂Culturing in an incubator.

7. After the cell fusion rate reached 80%, the medium was washed away, 0.5mL of high-glucose DMEM complete medium containing 10% fetal bovine serum was added to the control wells, and 0.5mL of MSC adipogenic induction medium was added to the other 3 well experimental wells. The plates were replaced at 30 ℃ with 5% CO₂And continuing culturing in the incubator.

8. Changing the liquid every 2-3 days. When the culture medium is changed, the original culture medium in the hole is firstly sucked and discarded, then 0.5mL of the corresponding culture medium is added, and the induction time is 15-20 days.

Second, dyeing identification

1. The dyeing identification of adipogenic induction differentiation culture adopts a neutral lipid oil red O dyeing method.

2. And (3) sample fixation treatment: the culture medium was carefully aspirated from the 24-well plate, and 300. mu.L of PBS buffer was added to each well to wash the cell surface. PBS wash was carefully aspirated off and 300. mu.L of BI's Adipo-Fixation was added to each well, covering the entire growth surface. And standing for 30min at room temperature, carefully absorbing and discarding BI Adipo-fire, adding 300 mu L of BI Adipo-wash I washing solution into each hole, cleaning the cell surface, and standing for 2-3 min. The BI's Adipo-Wash I was carefully withdrawn.

3. Sample staining treatment: adding an Adipo-Staining A and an Adipo-Staining B into a mixture of 3: 2, and mixing to obtain the dyeing working solution. Carefully add 300. mu.L of BI staining solution to cover the entire growth surface and allow to stand at room temperature for 30 min. Carefully remove the BI staining solution, carefully add Wash II at 300. mu. LBI, rinse the surface, aspirate Wash II, repeat the previous steps, and rinse the cells again (if the supernatant is still very red, the rinse time can be extended or rinsed once more, taking care not to rinse the cells off). Add 300. mu.L of Adipo-Insection to each well. Upon observation with an optical microscope, the lipid material exhibited a typical red color.

The results are shown in fig. 2, in which the serum-free acclimation experimental group a in fig. 2 shows lipid substances with typical red color, and the cells of the control group b in fig. 2 do not show lipid substances with typical red color.

The results of examining 5 test cells of examples 2 to 6, 6 test cells of example 7, the test cell of example 81, and the test cell of example 91 by referring to the method of this test example 2 showed that these cells all exhibited typical red lipid substances.

Test example 3: serum-free domesticated MSC cell chondrogenic induced differentiation and staining experiment

Reagent preparation and cell culture treatment

1. The experiments were started by placing trypsin, MSCgo Chondrogenic Differentiation basic Medium, MSCgo Chondrogenic Differentiation Supplement Mix in a 37 ℃ incubator for preheating.

3. cartilage induction culture and configuration: 10mL of Supplement Mix was pipetted into 100mL of Chondrogenic Differentiation basic Medium.

4. The serum-free acclimated MSC cells in the logarithmic growth phase of P5 obtained in example 1 were collected, digested with trypsin, and the flask was gently shaken to allow trypsin to spread on the bottom surface of the flask. Digesting for about 1min, observing cell shrinkage and clustering under a microscope, slightly beating the culture flask to make the cells shed to the bottom of the culture flask in a flowing sand shape, adding a complete culture medium with the same volume as that of trypsin to stop digestion, blowing off the cells by using a pipette, and collecting cell suspension in a 15mL centrifuge tube.

Second, cartilage induction

The first scheme is as follows:

1. according to 1 × 10⁷cells/mL were seeded at a density of 10. mu.L per well in 3 culture wells of a 24-well cell culture plate. Adding 1mL of sterile PBS into the peripheral blank holes, and sealing the edges for keeping humidity;

2. placing the 24-well cell culture plate into 5% CO₂Culturing in incubator for 2 hr;

3. after the cells adhere to the wall, taking 1 hole of the cells as a control group, and adding 1mL of high-glucose DMEM medium containing 10% FBS; in addition, 3 holes are used as experimental groups, and 0.5mL of MSC is added to form a cartilage induction culture medium;

4. charging 5% CO₂Continuously culturing in an incubator;

5. the culture medium is replaced every 3 days, and the induction time is 14-21 days.

Scheme II:

1. according to 6X 10⁵cell/mL, resuspending the MSC cell pellet, and preparing 4mL of MSC cell suspension;

2. the cell suspension was plated in 24-well plates at 37 ℃ with 1mL per well5% CO of₂Continuously culturing in an incubator;

3. washing the culture solution after 24hr, adding 0.5mL high sugar medium containing 10% FBS to 1 well of the culture solution as control well, adding 0.5mL MSC cartilage induction medium to another 3 wells of the culture solution as experimental group, adding 5% CO₂Culturing at 37 deg.C in incubator.

4. Changing the culture medium every 3-4 days, wherein the culture medium in the holes is firstly sucked away when the culture medium is changed, then 0.5mL of the corresponding culture medium is added, and the induction time is 14-21 days.

Third, dyeing identification

1. The dyeing identification of the chondrogenesis induced differentiation culture adopts an alcian dyeing method;

2. and (3) sample fixation treatment: the culture medium was carefully aspirated from the 24-well plate, and 400. mu.L of PBS buffer was added to each well to wash the cell surface. PBS wash was carefully aspirated off and 400. mu.L of BI's Fixation Solution was added to each well, covering the entire growth surface. Standing for 30min at room temperature, carefully absorbing and discarding the BI Fixation Solution, adding 200 mu L of BI wash I lotion into each hole, and standing for 2-3 min;

3. sample staining treatment: absorbing and removing Wash I, adding 300 mu L of stabilizing solution of BI, uniformly infiltrating the bottom surface, and dyeing overnight at room temperature in a dark place;

4. discarding the stabilizing solution, adding 300 mu L of BI Wash II, and rinsing the cells;

5. removing the Wash II by suction, adding 300 mu L of BI Wash II, and rinsing again (if the supernatant is still blue, the rinsing time can be prolonged and the rinsing can be performed again);

6. adding 300 mu L of BI observation Solution; cells successfully differentiated by chondrogenesis induction appear dark blue when observed by an optical microscope.

The results of the first protocol are shown in fig. 3, in which a serum-free acclimated experimental group showed cells exhibiting a typical deep blue color, and b control group cells showed no cells exhibiting a typical deep blue color in fig. 3. The results of protocol two are essentially the same as those of protocol one.

The results of examining 5 test cells of examples 2 to 6, 6 test cells of example 7, test cell of example 81, and test cell of example 91 were examined by the method of test example 3 (protocol one), and all of these cells exhibited typical dark blue cells.

The results of the above test examples 1 to 3 show that the human mesenchymal stem cells obtained by the serum-free in vitro acclimation culture method according to examples 1 to 9 of the present invention exhibit the typical differentiation performance of mesenchymal stem cells into osteoblasts, chondroblasts and adipocytes.

Test example 4: using Annexin V/PI reagent for detecting early/late apoptosis of P5 generation domesticated cells

Apoptosis is one of the basic characteristics of cells, and plays an important role in embryonic development, tissue repair, internal environment stabilization and the like of organisms. Annexin V is Ca2 with molecular weight of 35.8KD⁺The dependent phospholipid binding protein can be specifically combined with Phosphatidylserine (PS) which is overturned out of a membrane in the early apoptosis process of cells with high affinity. After FITC-Annexin V is combined to apoptotic cells, under the excitation of blue light, green fluorescence is emitted, and the apoptotic cells and normal cells are distinguished. Propidium Iodide (PI) is a nucleic acid dye that does not penetrate the intact cell membrane, but penetrates damaged membranes of late apoptotic and dead cells and red stains the nucleus. By matching FITC-Annexin V to PI, cells in the early stage of apoptosis can be distinguished from cells in the late stage.

Test materials in this test example: the mesenchymal stem cells obtained by serum-free acclimation culture according to the method of the present invention (the test cells of examples 1 to 9, for example, the P5 mesenchymal stem cells of example 1) and the P5 mesenchymal stem cells obtained by serum-free acclimation culture according to the method of example 1 of CN108642002A (201810047983.2) were used.

1. Taking the serum-free domesticated P5 to be tested to replace the mesenchymal stem cells, sucking and discarding the complete culture medium by a pipette, rinsing the culture bottle for 30s by 20mL of PBS, and then sucking and discarding;

2. 2mL of trypsin solution (0.25%) pre-warmed to 37 ℃ was added to the flask, and the flask was gently shaken to allow trypsin to spread on the bottom surface of the flask. Digesting for about 1min, observing cell shrinkage and clustering under a microscope, slightly beating the culture bottle to enable the cells to fall off to the bottom of the culture bottle in a flowing sand shape, adding a complete culture medium with the same volume as that of trypsin to stop digestion, blowing off the cells by using a pipette, and collecting cell suspension in a 15mL centrifuge tube;

3. centrifuging the cell suspension in a centrifuge at 1000rpm for 5min, removing supernatant, re-suspending cell precipitate with PBS pre-cooled to 4 deg.C, and centrifuging at 1000rpm for 5min to rinse the cells;

4. diluting 3mL of Binding Buffer (10X) to 30mL with 27mL of deionized water;

5.1 mL of 1 × Binding Buffer suspension cells are used, centrifugation is carried out for 10min at 1000rpm, and the supernatant is discarded;

6. resuspend cells with 1mL of 1 × Binding Buffer to a cell density of 1 × 10⁷cell/mL;

7. a1.5 mL EP tube was filled with 100. mu.L of cell suspension, i.e., 1X 10 cells⁶cell/mL;

8. then 5 mul of Annexin V-FITC is added into the tube, mixed evenly and lightly, incubated for 10min at room temperature in the dark;

9. adding 5 μ L of PI, incubating at room temperature in dark for 5 min;

10. adding PBS to 500 mu L, gently mixing, performing flow-type machine, detecting cell expression amount at 488nm, collecting 75 ten thousand cells in each test group, and calculating the ratio of early apoptosis to late apoptosis/death of the cells (n is the mean value of 5);

11. the results of determination and calculation show that the mesenchymal stem cells obtained by the serum-free domestication culture method have excellent results in the two parameters of the early apoptosis cell ratio and the late apoptosis/death cell ratio.

As a result: the 6 test cells of examples 1 to 6 had an early apoptotic cell ratio of 23.5% to 25.2% and a late apoptotic/dead cell ratio of 13.6% to 15.1%, for example, the P5 stem cell of example 1 had an early apoptotic cell ratio of 24.3% and a late apoptotic/dead cell ratio of 14.4%; the 6 test cells of example 7 had an early apoptotic cell ratio in the range of 12.4% to 13.3% and an late apoptotic/dead cell ratio in the range of 6.8% to 7.7%, for example, the P5 stem cells of example 71 had an early apoptotic cell ratio of 12.7% and an late apoptotic/dead cell ratio of 7.4%; the 6 test cells of example 8 had an early apoptotic cell ratio in the range of 23.7% to 25.7% and an late apoptotic/dead cell ratio in the range of 13.7% to 15.3%, for example, the P5 stem cells of example 81 had an early apoptotic cell ratio of 23.9% and an late apoptotic/dead cell ratio of 14.8%; the 6 test cells of example 9 had an early apoptotic cell ratio in the range of 23.4% to 24.7% and an late apoptotic/dead cell ratio in the range of 13.8% to 15.0%, for example, the P5 stem cells of example 91 had an early apoptotic cell ratio of 23.9% and an late apoptotic/dead cell ratio of 14.4%; the proportion of CN108642002A early apoptotic cells was 33.4% and the proportion of late apoptotic/dead cells was 21.7%.

According to the results of the test example 4, the mesenchymal stem cells obtained by the serum-free acclimation culture method of the invention have better performance than the mesenchymal stem cells obtained by the prior art. In particular, it was unexpectedly found that the simultaneous addition of a diol compound and a magnesium salt to an MSC acclimatization medium supplemented with transferrin and insulin with a gradual depletion of fetal bovine serum can significantly improve the performance of the cells.

Test example 5: detection of phenotype of serum-free acclimated MSC cells

The cells cultured by serum-free domestication culture of the P5 generation obtained in example 1 and the mesenchymal stem cells cultured by serum of the P5 generation obtained in example 10 are taken respectively, the cell surface markers are detected by flow cytometry, and whether the change of the cell surface markers in the domestication culture process is different from that in the conventional culture process is observed. The specific implementation mode is as follows: digesting and collecting P5 serum-free domesticated MSC cells and conventionally cultured MSC cells, counting, and taking 8 × 10⁶Each cell is divided into 16 tubes; washing with PBS once, and centrifuging at 1500rpm for 10 min; discarding the supernatant, leaving 100-200 mu L of the supernatant, and blowing and beating the uniformly mixed cells; adding FITC-labeled CD73 antibody 10 mu L, PerCP-Cy5.5-labeled CD90 antibody 10 mu L, PerCP-Cy5.5-labeled CD105 antibody 10 mu L, PE-labeled HLA-DR antibody 10 mu L, and setting a tube as a blank control; reacting at 4 ℃ in the dark for 30 min; PBS wash once, centrifuge at 1500rpm10 min; the supernatant of the directly labeled cells is discarded, 200 mu L of PBS is added to blow and mix the cells evenly, 200 mu L of 1% paraformaldehyde is fixed, the cells are placed at 4 ℃ to be detected, and the cells are detected by an up-flow cytometer within 3 days.

The results are shown in FIG. 4. As can be seen from the results in the figure, the results of the flow cytophenotype of the serum-free acclimatized cultured cells were consistent with those of the serum-containing cultured cells.

Referring to the method of test example 5, the 5 types of test cells of examples 2 to 6, the 6 types of test cells of example 7, the test cell of example 81, and the test cell of example 91 were tested, and the results shown in fig. 4 were substantially the same, indicating that the phenotype results of these serum-free acclimated cultured cells were consistent with the phenotype results of flow cells of serum-containing cultured cells, indicating that the mesenchymal stem cells obtained by the serum-free acclimated culturing methods of examples 1 to 9 of the present invention exhibited excellent cell performance.

In addition, in supplementary example a, with reference to the method of example 1, except that transferrin concentration thereof was changed to 8ng/mL and insulin concentration thereof was changed to 12ng/mL, or transferrin concentration thereof was changed to 12ng/mL and insulin concentration thereof was changed to 8ng/mL, two kinds of P5 generation serum-free acclimatized mesenchymal stem cells, which were respectively referred to as supplemented a1 and supplemented a2, were obtained; in addition, in supplementary example b, with reference to the method of example 71, except that the concentration of 3- (2-methoxyphenoxy) -1, 2-propanediol was changed to 0.08mg/mL and the concentration of magnesium chloride was changed to 6. mu.g/mL in terms of magnesium ion, or the concentration of 3- (2-methoxyphenoxy) -1, 2-propanediol was changed to 0.12mg/mL and the concentration of magnesium chloride was changed to 4. mu.g/mL in terms of magnesium ion, two kinds of P5-substituted serum-free acclimatized cultured mesenchymal stem cells, which were respectively referred to as "b-supplemented 1" and "b-supplemented 2", were obtained. The results of the tests on the parameters of the four cells, which were determined by the methods of test examples 1-5, were substantially the same as those of the P5 cell of example 1 for the two complement a1 and a2 cells, and the results of the tests on the parameters of the two complement b1 and b2 cells were substantially the same as those of the P5 cell of example 71, for example, the proportion of early apoptotic cells and the proportion of late apoptotic/dead cells of the complement a1 cells were 23.7% and 14.6%.

The examples of the present invention should be construed as merely illustrative and not a limitation of the scope of the present invention. After reading the description of the invention, one skilled in the art can make various changes and modifications to the invention, and such equivalent changes and modifications also fall into the scope of the invention defined by the claims.

Claims

1. An acclimatization medium for serum-free in vitro acclimatization culture of human mesenchymal stem cells, comprising: 8-12 ng/mL of transferrin, 8-12 ng/mL of insulin, 0-9.5% of fetal bovine serum and a balanced DMEM/F12 culture medium.

2. The acclimatizing medium according to claim 1, comprising: 10ng/mL of transferrin, 10ng/mL of insulin, 0-9.5% of fetal bovine serum and a balanced DMEM/F12 culture medium.

3. The acclimatization medium according to claim 1, further comprising 3- (2-methoxyphenoxy) -1, 2-propanediol and magnesium chloride; for example, the concentration of 3- (2-methoxyphenoxy) -1, 2-propanediol is 0.08-0.12 mg/mL; for example, the magnesium chloride is 4-6 μ g/mL in terms of magnesium ion concentration; for example, the concentration of 3- (2-methoxyphenoxy) -1, 2-propanediol is 0.1 mg/mL; for example, magnesium chloride is present in a magnesium ion concentration of 5. mu.g/mL; for example, these include: 8-12 ng/mL of transferrin, 8-12 ng/mL of insulin, 0.08-0.12 mg/mL of 3- (2-methoxyphenoxy) -1, 2-propylene glycol, 4-6 mu g/mL of magnesium chloride in terms of magnesium ion concentration, 0-9.5% of fetal bovine serum and a balanced DMEM/F12 culture medium; for example, these include: 10ng/mL of transferrin, 10ng/mL of insulin, 0.1mg/mL of 3- (2-methoxyphenoxy) -1, 2-propylene glycol, 5 mu g/mL of magnesium chloride in terms of magnesium ion concentration, 0-9.5% of fetal calf serum and a balanced DMEM/F12 culture medium.

4. The acclimatization medium according to claim 1, wherein the serum-free in vitro acclimatization culture of human mesenchymal stem cells is performed according to the following method:

(1) cleaning the surface of the placenta with a tissue cleaning solution to remove surface blood stasis, shearing umbilical cord and removing internal blood vessels;

(2) stripping Wharton's jelly in umbilical cord, cleaning, and shearing into 2-3 piecesmm³The small blocks are transferred to T75 culture bottles, and each bottle contains 1 mL;

(3) add slowly 10mL of MSC complete medium to the flask, gently shake the flask to allow the umbilical cord tissue pieces to lay flat in the flask, 5% CO at 37 deg.C₂Performing static culture in an incubator, supplementing liquid once every 2-3 days, supplementing liquid for 2-3 times, removing tissue blocks, replacing a total amount of MSC complete culture medium, and continuing to culture until the cell grows to 70% fusion degree, and then digesting the obtained cell;

(4) removing the culture medium in the culture bottle by suction, sucking PBS to rinse the culture bottle to remove residual fetal calf serum, adding 3mL of 0.25% trypsin solution for digestion, tapping the culture bottle to make the cells fall to the bottom of the culture bottle, adding 10mL of MSC complete culture medium to neutralize the trypsin so as to stop the digestion process, blowing off the cells by a pipette, collecting cell suspension in a centrifuge tube, centrifuging, removing the supernatant, and obtaining the cell with the cell precipitation marked as P0 generation;

(5) the P0 cell pellet was resuspended in 10mL of MSC acclimation medium containing less than 10% fetal bovine serum, the cells were counted, and then the cell count was 1X 10 according to the inoculation density⁴Individual MSC cells/cm²Inoculating into T75 culture bottle, supplementing the above MSC acclimatization culture medium to 10mL, and culturing at 37 deg.C with 5% CO₂Standing and culturing for more than 72h in an incubator until the cell fusion degree reaches 80%, sucking and removing a culture medium in a culture bottle, sucking PBS to rinse the culture bottle to remove residual fetal calf serum, adding 3mL of 0.25% trypsin solution for digestion, slightly beating the culture bottle to enable cells to fall to the bottom of the culture bottle, adding 10mL of MSC acclimation culture medium used in the step to neutralize trypsin to terminate the digestion process, blowing off the cells by using a pipettor, collecting cell suspension in a centrifuge tube, centrifuging, and removing a supernatant to obtain a cell precipitate which is marked as P1 generation cells;

(6) treating the cells obtained in the previous step in the operation process by using the culture and digestion method in the step (5) by using an MSC (mesenchymal stem cell) acclimation culture medium for sequentially reducing the concentration of fetal calf serum to be finally 0% to obtain the final serum-free in-vitro acclimation-cultured mesenchymal stem cells; optionally (c) is

(7) And (4) continuously culturing the mesenchymal stem cells of the last generation obtained in the last step and subjected to serum-free domestication culture by using a domestication culture medium containing 0% fetal calf serum MSC, and carrying out passage.

5. The acclimatization medium according to claim 4, wherein the tissue washing solution is a 0.9% physiological saline solution containing 1% penicillin, 1% streptomycin.

6. The acclimatizing medium according to claim 4, wherein the MSC complete medium is DMEM/F12 medium containing 10% fetal bovine serum; or, in the step (3), the solution is replenished once every 2-3 days, and 3-4mL of MSC complete culture medium is replenished every time; or, in the step (4), adding a trypsin solution, slightly shaking the culture bottle to enable the trypsin to fully cover the cell surface, digesting for 1min, observing the cell to shrink into a circle under a microscope, slightly beating the culture bottle to enable the cell to fall off to the bottom of the culture bottle in a flowing sand shape; or, in the step (5), the P0 generation cell sediment is resuspended by using MSC acclimation culture medium containing 7-9.5% fetal calf serum; or, in the step (5), the cell pellet of P0 generation is resuspended in MSC acclimation medium containing 8-9.5% fetal bovine serum, for example, 8%, 8.5%, 9%, or 9.5% fetal bovine serum; or, in the process of repeating the step (5) in the step (6), along with the increase of the cell generation, the concentration of the fetal calf serum in the MSC acclimation culture medium is reduced until the concentration of the fetal calf serum in the MSC acclimation culture medium is 0; or, in the step (6), gradually reducing the concentration of the fetal calf serum until the generation of P4-P10 to obtain the serum-free mesenchymal stem cells cultured by in vitro acclimation; or, in the step (7), the mesenchymal stem cells obtained by the in vitro domestication culture of the 0% fetal serum finally obtained in the step (6) are continuously cultured and passaged by using a domestication culture medium containing 0% fetal bovine serum MSC, and are continuously transferred to the P20 generation mesenchymal stem cells subjected to serum-free domestication culture.

7. A method for serum-free domestication culture of mesenchymal stem cells comprises the following steps:

(2) stripping Wharton's jelly in umbilical cord, cleaning, and shearing into 2-3mm pieces³The small blocks are transferred to T75 culture bottles, and each bottle contains 1 mL;

8. The method of claim 7, wherein the tissue wash is a 0.9% saline solution containing 1% penicillin and 1% streptomycin.

9. The method according to claim 7, wherein the MSC complete medium is DMEM/F12 medium containing 10% fetal bovine serum; or, in the step (3), the solution is replenished once every 2-3 days, and 3-4mL of MSC complete culture medium is replenished every time; or, in the step (4), adding a trypsin solution, slightly shaking the culture bottle to enable the trypsin to fully cover the cell surface, digesting for 1min, observing the cell to shrink into a circle under a microscope, slightly beating the culture bottle to enable the cell to fall off to the bottom of the culture bottle in a flowing sand shape; or, in the step (5), the P0 generation cell sediment is resuspended by using MSC acclimation culture medium containing 7-9.5% fetal calf serum; or, in the step (5), the cell pellet of P0 generation is resuspended in MSC acclimation medium containing 8-9.5% fetal bovine serum, for example, 8%, 8.5%, 9%, or 9.5% fetal bovine serum; or, in the process of repeating the step (5) in the step (6), along with the increase of the cell generation, the concentration of the fetal calf serum in the MSC acclimation culture medium is reduced until the concentration of the fetal calf serum in the MSC acclimation culture medium is 0; or, in the step (6), gradually reducing the concentration of the fetal calf serum until the generation of P4-P10 to obtain the serum-free mesenchymal stem cells cultured by in vitro acclimation; or, in the step (7), the mesenchymal stem cells obtained by the in vitro domestication culture of the 0% fetal serum finally obtained in the step (6) are continuously cultured and passaged by using a domestication culture medium containing 0% fetal bovine serum MSC, and are continuously transferred to the P20 generation mesenchymal stem cells subjected to serum-free domestication culture.

10. The method according to claim 7, said MSC acclimatization medium comprising: 8-12 ng/mL of transferrin, 8-12 ng/mL of insulin, 0-9.5% of fetal bovine serum and a balanced DMEM/F12 culture medium; or, the MSC acclimatization medium comprises: 10ng/mL of transferrin, 10ng/mL of insulin, 0-9.5% of fetal bovine serum and a balanced DMEM/F12 culture medium; or, the MSC acclimation culture medium further comprises 3- (2-methoxyphenoxy) -1, 2-propanediol and magnesium chloride; or the concentration of the 3- (2-methoxyphenoxy) -1, 2-propylene glycol is 0.08-0.12 mg/mL; or the magnesium chloride is 4-6 mu g/mL in terms of magnesium ion concentration; or the concentration of the 3- (2-methoxyphenoxy) -1, 2-propanediol is 0.1 mg/mL; or the magnesium chloride is 5 mug/mL in magnesium ion concentration; or, the MSC acclimatization medium comprises: 8-12 ng/mL of transferrin, 8-12 ng/mL of insulin, 0.08-0.12 mg/mL of 3- (2-methoxyphenoxy) -1, 2-propylene glycol, 4-6 mu g/mL of magnesium chloride in terms of magnesium ion concentration, 0-9.5% of fetal bovine serum and a balanced DMEM/F12 culture medium; or, the MSC acclimatization medium comprises: 10ng/mL of transferrin, 10ng/mL of insulin, 0.1mg/mL of 3- (2-methoxyphenoxy) -1, 2-propylene glycol, 5 mu g/mL of magnesium chloride in terms of magnesium ion concentration, 0-9.5% of fetal calf serum and a balanced DMEM/F12 culture medium.