CN113717933B

CN113717933B - Application of FGF7 in preparation of stem cell expansion and phenotype maintaining reagent

Info

Publication number: CN113717933B
Application number: CN202110755723.2A
Authority: CN
Inventors: 陈晓; 张鸿; 茵梓; 沈炜亮
Original assignee: Zhejiang University ZJU
Current assignee: Zhejiang University ZJU
Priority date: 2021-07-05
Filing date: 2021-07-05
Publication date: 2023-10-13
Anticipated expiration: 2041-07-05
Also published as: CN113717933A; CN117821380A

Abstract

The application relates to application of FGF7 in preparation of stem cell expansion and phenotype maintaining reagents, and belongs to the technical field of cell culture. Specifically, FGF7 can be added to promote stem cell proliferation and maintain its stem cell phenotype and tendinous phenotype during stem cell culture. The stem cell phenotype is achieved primarily by maintaining the expression level of stem cell surface markers, and the tendinous phenotype is achieved primarily by increasing the expression level of tendinous specific genes and proteins. The agent prepared by FGF7 and/or the stem cells cultured by the agent can be used for treating tissue injury.

Description

Application of FGF7 in preparation of stem cell expansion and phenotype maintaining reagent

Technical Field

The application belongs to the technical field of cell culture, in particular to application of FGF7 in preparing stem cell amplification and phenotype maintenance reagents and application of the prepared reagents in cell culture and tissue damage repair.

Background

Tendon injury is a common motor system injury. Sudden muscle contraction caused by external force can cause complete or partial tearing of the tendon starting point, called tendon rupture. If the tendon is repeatedly subjected to slight trauma for a long period of time or the tendon itself is worn chronically, tendon fracture is caused in a long period of time, which is called spontaneous tendon fracture. Tendon injury can cause pain, localized swelling, and dysfunction.

At present, tendon injury or fracture has not been treated perfectly, and clinical treatments are usually symptomatic treatments, including drug treatments, physical treatments, surgical treatments, such as direct suturing, autogenous or allogeneic transplantation, artificial synthetic material repair, and the like. However, the repairing and healing capacities are poor, the complication incidence rate is high, the long-term curative effect is unstable, and the problems of tendon adhesion, calcification, strength reduction, even re-fracture and the like are easy to occur.

Development of tissue engineering technology brings wide prospect for improving repair quality of tendons and ligaments. Tendon stem cells are one of ideal seed cell sources for tissue engineering, and have not only stem cell phenotype like bone marrow mesenchymal stem cells, but also tendon phenotype, and highly express tendon-specific genes and proteins such as collagen I, mucin C, fibronectin and the like. Therefore, tendon/ligament stem cells are seed cells that have great potential for use in tendon tissue engineering.

Tendon stem cells have limited sources and need to be applied to tissue engineering treatment after in vitro amplification. However, under the existing conventional cell culture technical conditions, tendon stem cells have a slow in-vitro expansion culture speed and are easy to lose phenotype. The regenerated tendon formed by tendon stem cells amplified by the prior culture technique still has obvious difference in mechanical properties, especially microstructure, from normal tendon, and the ultrastructure of the repaired tissue shows that the regenerated tendon is composed of a large number of small-diameter collagen fibers, and the small-diameter collagen fibers prove direct factors causing the low mechanical properties of the tendon after healing. Moreover, the tendon stem cells cultured in the prior art are easy to have phenotype loss phenomena such as ectopic ossification and the like when being used for tendon repair, so that tendon repair fails. Thus, there is currently no culture condition suitable for in vitro expansion and phenotypic maintenance of tendon stem cells.

The growth factor serving as an additive component of the culture medium has the advantages of controllability, convenience in operation and the like, and has been widely used in the fields of stem cell expansion, differentiation regulation and control and tissue engineering. The growth factor has good potential in promoting the change of cell fate and has good application prospect. Therefore, the provision of a proper growth factor for promoting the in vitro expansion and the phenotype maintenance of the tendon stem cells has important significance for the in vitro culture and clinical transformation application of the tendon stem cells.

Disclosure of Invention

Accordingly, it is an object of the present application to provide a suitable agent for preparing in vitro stem cell expansion and phenotype maintenance by using a growth factor, and it is found that fibroblast growth factor 7 (FGF 7) can maintain stem cell expansion and phenotype in vitro, and the application of fibroblast growth factor 7 (FGF 7) in preparing in vitro stem cell expansion and phenotype maintenance agent is realized.

In order to achieve the purpose of the application, the technical scheme adopted by the application is as follows:

the present application provides the use of fibroblast growth factor 7 (FGF 7) and/or FGF7 synthetic peptides for the preparation of a reagent for maintaining stem cell expansion and phenotype (in vitro).

Further, the phenotypes include stem cell phenotype and tendinous phenotype (expression of tendinous genes SCX, FOS). The stem cell phenotype is achieved primarily by maintaining the expression level of stem cell surface markers, and the tendinous phenotype is achieved primarily by increasing the expression level of tendinous specific genes and proteins (SCX, FOS).

Further, the stem cells are tendon stem cells, ligament stem cells, meniscus stem cells, mesenchymal stem cells, fat stem cells, bone stem cells or muscle stem cells; more preferably, the stem cells are tendon stem cells.

The FGF7 synthetic peptide refers to an amino acid sequence according to an effective fragment or a fragment combination of FGF7, and/or a polypeptide or oligopeptide with the same amino acid sequence prepared by a chemical synthesis method. Among them, the fragment effective for FGF7 can be synthesized by designing a primer after finding the corresponding amino acid sequence according to the existing literature report or by entrusting the synthesis by biological companies. The literature does not report that optimized peptide fragments can be found by means of proteolysis and peptide profiling, and then synthesized by designing primers or entrusted with biosystems.

Further, the FGF7 synthetic peptide may further include a mimetic peptide of FGF7, wherein the mimetic peptide of FGF7 is selected from a peptide library by using a receptor of FGF7, and the mimetic peptide has an amino acid sequence different from that of FGF7, but has an activity of FGF7 and has the advantage of having a small relative molecular mass, and the like, and similarly, the mimetic peptide of FGF7 may be synthesized by a biological company according to a known amino acid sequence of the mimetic peptide of FGF 7.

Further, the FGF7 and/or FGF7 synthetic peptide concentration ranges from 1 to 100ng/ml based on the total volume of the reagent. Preferably, the FGF7 and/or FGF7 synthetic peptide concentration ranges from 5 to 70ng/ml; more preferably, the FGF7 and/or FGF7 synthetic peptide concentration is between 10 and 40ng/ml.

Further, the FGF7 performs expansion of stem cells mainly by enhancing the stem cell expansion rate, shortening the cell doubling time, and increasing the number of cell expansion.

Further, the growth factor FGF7 performs phenotypic maintenance of stem cells mainly by maintaining the expression level of stem cell surface markers, and increasing the expression level of tendon-specific genes and proteins.

Further, in the above application, the reagent further comprises a basal medium; the basic culture medium is DMEM low-sugar culture medium, DMEM high-sugar culture medium, DMEM/F12 culture medium, F10 culture medium, MEM culture medium, BEM culture medium, RPMI 1640 culture medium, media 199 culture medium, IMDM culture medium, mTesr culture medium or E8 culture medium.

Further, in the above application, the reagent further comprises any one or two or more components selected from serum, growth factors, small molecules, hormones, proteins, synthetic peptides, polyamines, lipids, minerals, saccharides, organic acids, amino acids, reducing agents, vitamins, trace elements, antibiotics, buffers and pH adjusters.

Further, in the above application, the culture mode includes any one or more of two-dimensional culture, three-dimensional culture, adherent culture, suspension culture, static culture and dynamic culture.

An in vitro culture method of stem cells maintaining stem cell expansion and stem cell phenotype and tendinous phenotype, the method comprising the steps of: reagents prepared from fibroblast growth factor 7 (FGF 7) and/or FGF7 synthetic peptides are contacted with stem cells for in vitro culture of the stem cells. Preferably, in the above method, the stem cells are tendon stem cells, ligament stem cells, meniscus stem cells, mesenchymal stem cells, adipose stem cells, bone stem cells or muscle stem cells. More preferably, the stem cells are tendon stem cells.

Preferably, the FGF7 and/or FGF7 synthetic peptide concentration ranges from 1 to 100ng/ml based on the total volume of the reagent. Preferably, the FGF7 and/or FGF7 synthetic peptide concentration ranges from 5 to 70ng/ml; more preferably, the FGF7 and/or FGF7 synthetic peptide concentration is between 10 and 40ng/ml.

In the above method, the reagent further comprises a basal medium; the basic culture medium is DMEM low-sugar culture medium, DMEM high-sugar culture medium, DMEM/F12 culture medium, F10 culture medium, MEM culture medium, BEM culture medium, RPMI 1640 culture medium, media 199 culture medium, IMDM culture medium, mTesr culture medium and E8 culture medium.

In the method, the reagent further comprises any one or more than two components selected from serum, growth factors, small molecules, hormones, proteins, synthetic peptides, polyamines, lipids, minerals, saccharides, organic acids, amino acids, reducing agents, vitamins, trace elements, antibiotics, buffering agents and pH value regulators.

In the above method, the culture mode comprises any one or more of two-dimensional culture, three-dimensional culture, adherence culture, suspension culture, static culture and dynamic culture.

The application also provides stem cells obtained by the in vitro culture method.

The application also provides application of the stem cells in preparing medicaments or cell preparations for human and/or animal tissue injury.

The application has the beneficial effects that:

the present application discloses the use of fibroblast growth factor 7 (FGF 7) and/or FGF7 synthetic peptides for the preparation of an agent for maintaining stem cell expansion and phenotype (in vitro).

The reagent prepared by the FGF7 can support stem cell culture, the proliferation of cells obtained by the culture is superior to that of the prior art, the maintenance of the phenotype of stem cells and the phenotype of tendons obtained by the culture is obviously stronger than that of the prior art, and the quality of cells can be ensured to reach the tissue injury repair standard.

Drawings

FIG. 1 is a morphology of stem cells cultured according to an embodiment of the present application.

FIG. 2 is a bar graph showing the expression of tendon genes according to the examples of the present application compared with conventional culture in the prior art.

FIG. 3 is an immunofluorescence of tenascin SCX of an example of the present application compared to a conventional culture of the prior art.

FIG. 4 is a diagram showing the immunofluorescence of tenascin FOS according to the example of the present application compared with conventional culture in the prior art.

FIG. 5 is a fluorescent chart of the dead living cell staining of the 3D cultured stem cells according to the embodiment of the present application.

Detailed Description

The application is illustrated by way of example as to how it may be carried out, these being only a limited list within the spirit of the application and not limiting the application in any way.

Example 1

This example sets up two sets of medium, FGF7 medium (FGF 7) and prior art conventional medium (Ctrl). The cultured cells are tendon stem cells extracted from normal tendon tissue of human. The following are detailed experimental and detection steps:

reagent preparation

FGF7 medium (FGF 7)

The FGF7 medium is selected from DMEM low-sugar medium, and 5000ng FGF7 (final concentration of 10 ng/mL), 55mL of fetal bovine serum, 5mmol HEPES, 10000U of penicillin and 10000U of streptomycin are added to every 500mL of DMEM low-sugar medium.

Comparative example 1

Conventional culture medium (Ctrl)

The prior art conventional medium is selected from the group consisting of DMEM low sugar medium, and 55mL of fetal bovine serum, 5mmol of HEPES, 10000U of penicillin, and 10000U of streptomycin are added per 500mL of DMEM low sugar medium.

EXAMPLE 1 biological Activity Experimental example

Cultured cell treatment

Human tendon stem cells were prepared at about 1X10^4/cm ² Inoculating into orifice plate, culture dish or culture flask, culturing cells with FGF7 medium and conventional culture medium, respectively, and placing at 37deg.C and 5% CO ₂ The culture is carried out in a cell culture box, liquid is changed every 3 days until the culture is basically full, and experiments such as cell photographing, cell counting, gene expression detection, dead living cell staining, immunofluorescence and the like are carried out.

Analysis of experimental results

Cell morphology observations

In the above-mentioned treatment process of cultured cells, growth and morphological changes of tendon stem cells cultured in FGF7 medium were observed with an inverted phase contrast microscope, and recorded by microscopic photography.

As shown in fig. 1, it was shown under a 4X microscope that tendon stem cells can maintain good adherence under culture conditions of FGF7 addition, are cytosolic, and exhibit a fusiform cell morphology.

qPCR detection of Gene expression

Tendon stem cells were cultured according to approximately 1X10≡4/cm ² Culturing cells in 12-well plate with FGF7 culture medium and conventional culture medium, washing once with 1XPBS, adding RNA cell lysate, extracting RNA from cell with RNA extracting kit, reverse transcribing into cDNA, and Qpcr detecting relative expression of tendon gene in cell with analysis result, and drawing the relative expression bar graph of the gene with group as horizontal coordinate and relative expression amount as vertical coordinate.

As shown in fig. 2, QRT-PCR results showed that addition of FGF7 culture significantly increased expression of tendon stem cell tendinous gene SCX, FOS, BGN, COL and FMOD compared to comparative example 1 (i.e., ctrl), indicating that FGF7 was able to enhance human tendon stem cell tendinous phenotype.

Immunofluorescence detection of tendon gene expression

Tendon stem cells were transformed to approximately 1X10 ≡ ⁴ /cm ² Is planted in 12-well plates, cells are cultivated by FGF7 culture medium and conventional culture medium in the prior art, the culture medium is discarded at the 5 th day, 1XPBS is washed once, and 4% paraformaldehyde is fixedSCX and FOS tendon marker proteins were stained, and the result of staining cells was photographed under a fluorescence microscope.

As shown in fig. 3 and 4, immunofluorescence results showed that addition of FGF7 culture significantly increased expression of tendon stem cell tendon markers SCX and FOS compared to comparative example 1 (i.e., ctrl), indicating that FGF7 was able to enhance human tendon stem cell tendon phenotype.

Example 2

This example sets up two sets of medium, FGF7 medium (FGF 7) and prior art conventional medium (Ctrl). The cultured cells are human mesenchymal stem cells. The following are detailed experimental and detection steps:

reagent preparation

FGF7 medium (FGF 7)

The FGF7 medium is selected from DMEM low-sugar medium, and 10000ng FGF7 (final concentration of 20 ng/mL), 55mL of fetal bovine serum, 5mmol HEPES, 10000U of penicillin and 10000U of streptomycin are added to every 500mL of DMEM low-sugar medium.

Comparative example 1

Conventional culture medium (Ctrl)

The cell culture mode of the embodiment is the same as that of the embodiment I, and experiments show that the proliferation speed of the human mesenchymal stem cells cultured by the embodiment is higher than that of the comparative example 1, the cell activity rate is higher, the expression of tendon markers is stronger, and the culture reagent added with FGF7 is more suitable for in vitro expansion and phenotype maintenance of the human mesenchymal stem cells than that of the conventional culture medium in the prior art.

Example 3

This example sets up two sets of medium, FGF7 medium (FGF 7) and prior art conventional medium (Ctrl). The cultured cells are human ligament stem cells. The following are detailed experimental and detection steps:

reagent preparation

FGF7 medium (FGF 7)

The FGF7 culture medium is selected from DMEM low-sugar culture medium, and 20000ng FGF7 (final concentration of 40 ng/mL), 55mL of fetal bovine serum, 5mmol HEPES, 10000U of penicillin and 10000U of streptomycin are added to every 500mL of DMEM low-sugar culture medium.

Comparative example 1

Conventional culture medium (Ctrl)

The cell culture mode of the embodiment is the same as that of the embodiment I, and experiments show that the proliferation speed of the human ligament stem cells cultured by the embodiment is higher than that of the embodiment 1, the cell activity rate is higher, the expression of tendon markers is stronger, and the culture reagent added with FGF7 is more suitable for the in vitro expansion and phenotype maintenance of the human ligament stem cells than that of the conventional culture medium in the prior art.

Example 4

This example sets up two sets of medium, FGF7 medium (FGF 7) and prior art conventional medium (Ctrl). The cultured cells are from human adipose stem cells. The following are detailed experimental and detection steps:

reagent preparation

FGF7 medium (FGF 7)

The FGF7 medium is selected from DMEM low-sugar medium, 25000ng FGF7 (final concentration of 50 ng/mL), 55mL of fetal bovine serum, 5mmol HEPES, 10000U of penicillin and 10000U of streptomycin are added to every 500mL of DMEM low-sugar medium.

Comparative example 1

Conventional culture medium (Ctrl)

The cell culture mode of the embodiment is the same as that of the first embodiment, and experiments show that the proliferation speed of the human adipose-derived stem cells cultured in the embodiment is higher than that of the human adipose-derived stem cells cultured in the comparative example 1, the cell viability is higher, the expression of tendon markers is stronger, and the culture reagent added with FGF7 is more suitable for in-vitro expansion and phenotype maintenance of the human adipose-derived stem cells than the conventional culture medium in the prior art.

Example 5

This example sets up two sets of medium, FGF7 medium (FGF 7) and prior art conventional medium (Ctrl). The cultured cells are stem cells from human tendons. The following are detailed experimental and detection steps:

reagent preparation

FGF7 medium (FGF 7)

The FGF7 culture medium is selected from DMEM low-sugar culture medium, and 35000ng FGF7 (final concentration of 70 ng/mL), 55mL of fetal bovine serum, 5mmol HEPES, 10000U of penicillin and 10000U of streptomycin are added into every 500mL of DMEM low-sugar culture medium.

Comparative example 1

Conventional culture medium (Ctrl)

The cell culture mode of the embodiment is the same as that of the embodiment I, and experiments show that the proliferation speed of the human tendon stem cells cultured in the embodiment is higher than that of the embodiment 1, the cell activity rate is higher, the expression of tendon markers is stronger, and the culture reagent added with FGF7 is more suitable for in-vitro expansion and phenotype maintenance of the human tendon stem cells than that of the conventional culture medium in the prior art.

Example 6

reagent preparation

FGF7 medium (FGF 7)

The FGF7 culture medium is selected from DMEM low-sugar culture medium, and 500ng FGF7 (100 ng/mL final concentration) is added to 500mL DMEM low-sugar culture medium, 55mL fetal bovine serum, 5mmol HEPES, 10000U penicillin and 10000U streptomycin.

Comparative example 1

Conventional culture medium (Ctrl)

Example 7

This example sets up two sets of medium, FGF7 medium (FGF 7) and prior art conventional medium (Ctrl). The cultured cells were tendon stem cells from rats. The following are detailed experimental and detection steps:

reagent preparation

FGF7 medium (FGF 7)

The FGF7 medium is selected from DMEM low-sugar medium, and 2500ng FGF7 (5 ng/mL final concentration) and 2500ng FGF7 synthetic peptide (5 ng/mL final concentration) are added to every 500mL DMEM low-sugar medium, 55mL fetal bovine serum, 5mmol HEPES, 10000U penicillin and 10000U streptomycin.

Comparative example 1

Conventional culture medium (Ctrl)

The cell culture mode of the embodiment is the same as that of the embodiment I, and experiments show that the proliferation speed of the rat tendon stem cells cultured in the embodiment is higher than that of the rat tendon stem cells cultured in the comparative example 1, the cell activation rate is higher, the expression of tendon markers is stronger, and the culture reagent added with FGF7 is more suitable for in vitro amplification and phenotype maintenance of the rat tendon stem cells than that of the rat tendon stem cells cultured in the conventional culture medium in the prior art.

Example 8

reagent preparation

FGF7 medium (FGF 7)

The FGF7 culture medium is selected from DMEM low-sugar culture medium, 500ng FGF7 (with a final concentration of 1 ng/mL) is added to 500mL of DMEM low-sugar culture medium, 5000ng FGF7 synthetic peptide (with a final concentration of 10 ng/mL), 55mL of fetal bovine serum, 5mmol of HEPES, 10000U of penicillin and 10000U of streptomycin.

Comparative example 1

Conventional culture medium (Ctrl)

The cell culture mode of the embodiment is the same as that of the embodiment I, and experiments show that the proliferation speed of the human tendon stem cells cultured in the embodiment is higher than that of the embodiment 1, the cell activity rate is higher, the expression of tendon markers is stronger, the culture reagent added with FGF7 is more suitable for the in-vitro proliferation and the phenotype maintenance of the human tendon stem cells than the conventional culture medium in the prior art, and the FGF synthetic peptide can promote the proliferation and the phenotype maintenance of the stem cells.

Example 9

This example sets up two sets of medium, FGF7 medium (FGF 7) and prior art conventional medium (Ctrl). The cultured cells were mouse tendon stem cells. The following are detailed experimental and detection steps:

reagent preparation

FGF7 medium (FGF 7)

The FGF7 medium is selected from DMEM low-sugar medium, and 12500ng FGF7 (final concentration of 25 ng/mL), 55mL of fetal bovine serum, 5mmol HEPES, 10000U of penicillin and 10000U of streptomycin are added to every 500mL of DMEM low-sugar medium.

Comparative example 1

Conventional culture medium (Ctrl)

The cell culture mode of the embodiment is the same as that of the embodiment I, and experiments show that the proliferation speed of the tendon stem cells of the mice cultured in the embodiment is higher than that of the tendon stem cells of the mice cultured in the comparative example 1, the cell activation rate is higher, the expression of tendon markers is stronger, and the culture reagent added with FGF7 is more suitable for in vitro expansion and phenotype maintenance of the tendon stem cells of the mice than the conventional culture medium in the prior art.

Example 10

This example sets up a set of media, FGF7 media (FGF 7). The cultured cells are stem cells from human tendons. The following are detailed experimental and detection steps:

reagent preparation

FGF7 medium (FGF 7)

The FGF7 medium is selected from DMEM low-sugar medium, 7500ng FGF7 (final concentration of 15 ng/mL), 55mL of fetal bovine serum, 5mmol HEPES, 10000U of penicillin and 10000U of streptomycin are added to every 500mL of DMEM low-sugar medium.

EXAMPLE 10 biological Activity test example

Cultured cell treatment

Human tendon stem cells were cultured according to about 2X 10-5/cm ² 20mg of 3D microcarrier (Beijing Hua niche organism, 3D FloTrix cell expansion set) was inoculated, and the cells were cultured in a low adhesion 6-well plate, cultured in FGF7 medium, placed in a cell incubator at 37℃with 5% CO2, and cultured for 4 days with one liquid change every 3 days, followed by cell staining, photographing, gene expression detection, dead and living cell staining, etc.

Analysis of experimental results

Staining of dead living cells

Taking cells cultured for 4 days in 3D, centrifuging for 5min at 800rpm, washing for one time by 1XPBS, and using a dead living cell kit to dye the dead living cells, wherein the cells are stained with green or red, and the cells are stained with red or dead cells, and observing the dyeing condition of the cells under a fluorescence microscope.

As shown in fig. 5, fluorescent microscope photographing shows that human tendon stem cells can maintain good adherence and high cell viability under the 3D culture condition of FGF7 addition. It was demonstrated that FGF 7-added cultures were practically suitable for stem cell cultures in 3D.

Culture effect detection of medium (reagent) supplemented with FGF7 in the above examples:

cell proliferation and cell viability assays

Cell counting by trypan blue counting, subjecting digested cells to 1200rpm, centrifuging for 5min, discarding supernatant, adding corresponding culture medium, preparing single cell suspension, diluting appropriately, transferring 1mL of cell suspension into an EP tube, adding 0.4% trypan blue solution, mixing, adding a blood cell counting plate, and observing and counting. If the cell membrane is intact, the cell is not stained with trypan blue, then it is a normal cell; if the cell membrane is incomplete and broken, trypan blue dye enters the cell, and the cell turns blue, namely the necrotic cell. The number of living cells and the number of dead cells were counted under a microscope, and the cell counting method was as follows: (total number of four cells/4). Times.10 ⁴ X fold dilution = cell number of cell suspension/mL, cell viability was calculated: cell viability = number of viable cells/total number of cells x 100%.

As shown in table one, which is the number of cells and the cell viability of the cells of the examples and comparative examples of the present application, it can be seen that the experimental group to which FGF7 was added exhibited faster cell proliferation ability and higher cell viability than the conventional culture control group.

Table-cell proliferation and cell viability for each example and comparative example

Flow analysis for detecting expression condition of stem cell surface marker

The P3 or P5 generation stem cells are prepared according to about 1X10≡4/cm ² Is planted in 10cm dishesCells were cultured in FGF7 medium of each example and conventional medium of the prior art, respectively, and placed at 37℃in 5% CO ₂ The culture is carried out in a cell culture box of (2) by changing the liquid once every 3 days until the cell culture box is basically full, discarding the culture medium, washing by 1XPBS, digesting by pancreatin for 2 minutes, centrifuging for 5 minutes, discarding the supernatant, sealing, separating the tubes, staining the CD marker on the surface of the stem cells, staining the CD105, CD90, CD44, CD34, CD18 and other flow type direct labeling antibodies, detecting on the machine, and analyzing the expression condition of the CD marker.

As shown in table two, CD105, CD90 and CD44 are positive expression markers of stem cells, CD34 and CD18 are negative expression markers of stem cells, and the results show that the positive marker expression of each example group is greater than 95%, the negative marker expression is less than 2%, which accords with the international definition of stem cells, and accords with the characteristics of stem cells more than the comparative example group. Thus, it was demonstrated that cells cultured with FGF 7-supplemented medium (reagent) were able to maintain their stem cell characteristics, more in line with stem cell characteristics.

Table II examples and comparative examples expression of CD markers on stem cell surfaces

qPCR detection of tendon gene expression

The stem cells are prepared according to a ratio of about 1X 10-4/cm ² Culturing cells in 12-well plates by using FGF7 culture medium of each example and conventional culture medium of the prior art, washing once by 1XPBS at day 5, adding RNA cell lysate, extracting cell RNA by using an RNA extraction kit, performing reverse transcription to form cDNA, then performing Qpcr on the cDNA sample by using a sample loading machine to detect the relative expression condition of tendon-related genes in the cells, analyzing the result, and comparing and counting the relative expression quantity of the tendon-related genes of each example by using Ctrl group gene expression quantity as 1.

As shown in table three, QRT-PCR results showed that the addition of FGF7 culture significantly increased expression of stem cell tendon genes SCX, FOS compared to comparative example 1 (i.e., ctrl), indicating that FGF7 was able to enhance stem cell tendon phenotype.

Table three relative expression of tendon genes for examples and comparative examples

Group of experiments	Relative expression level of SCX	FOS relative expression level
			Example 1	1.85	2.04
Example 2	3.16	3.82
			Example 3	3.62	4.24
Example 4	3.12	3.63
			Example 5	2.83	3.21
Example 6	2.52	2.72
			Example 7	1.75	2.16
Example 8	1.18	1.21
			Example 9	3.24	4.76
Example 10	3.26	4.68
			Comparative example 1	1	1

The above description is only illustrative of the preferred embodiments of the present application and of the principles of the technology employed. It will be appreciated by persons skilled in the art that the scope of the application referred to in the present application is not limited to the specific combinations of the technical features described above, but also covers other technical features formed by any combination of the technical features described above or their equivalents without departing from the inventive concept. Such as the above-mentioned features and the technical features disclosed in the present application (but not limited to) having similar functions are replaced with each other.

Claims

Use of fgf7 in the preparation of a reagent for maintaining stem cell expansion and phenotype; it is characterized in that the method comprises the steps of,

the phenotype is a stem cell phenotype and a tendon phenotype;

the stem cells are tendon stem cells;

the concentration of FGF7 is in the range of 1-100ng/ml based on the total volume of the reagent.
2. The use according to claim 1, characterized in that: the concentration of FGF7 is in the range of 5-70ng/ml based on the total volume of the reagent.
3. The use according to claim 2, characterized in that: the concentration of FGF7 is in the range of 10-40ng/ml based on the total volume of the reagent.
4. The use according to claim 1, characterized in that: the reagent further comprises a basal medium; the basic culture medium is DMEM low-sugar culture medium, DMEM high-sugar culture medium, DMEM/F12 culture medium, F10 culture medium, MEM culture medium, BEM culture medium, RPMI 1640 culture medium, media 199 culture medium, IMDM culture medium, mTesr culture medium and E8 culture medium.
5. The use according to claim 4, characterized in that: the reagent also comprises any one or more than two components of serum, growth factors, hormones, proteins, synthetic peptides, polyamines, lipids, minerals, saccharides, organic acids, amino acids, vitamins, trace elements, antibiotics, buffering agents and pH value regulators.
6. An in vitro culture method of tendon stem cells that maintain stem cell expansion and stem cell phenotype and tendinous phenotype, the method comprising the steps of: the preparation method comprises the steps of (1) contacting an agent prepared by FGF7 with tendon stem cells for in-vitro culture of the tendon stem cells;

the concentration of FGF7 is 1-100ng/ml based on the total volume of the reagent;

the reagent further comprises a basal medium; the basic culture medium is DMEM low-sugar culture medium, DMEM high-sugar culture medium, DMEM/F12 culture medium, F10 culture medium, MEM culture medium, BEM culture medium, RPMI 1640 culture medium, media 199 culture medium, IMDM culture medium, mTesr culture medium and E8 culture medium;

the reagent also comprises any one or more than two components of serum, growth factors, hormones, proteins, synthetic peptides, polyamines, lipids, minerals, saccharides, organic acids, amino acids, vitamins, trace elements, antibiotics, buffering agents and pH value regulators;

the culture mode comprises any one or more of two-dimensional culture, three-dimensional culture, adherence culture, suspension culture, static culture and dynamic culture.
7. The in vitro culture method according to claim 6, wherein: the concentration of FGF7 is in the range of 5-70ng/ml based on the total volume of the reagent.
8. The in vitro culture method according to claim 7, wherein: the concentration of FGF7 is in the range of 10-40ng/ml based on the total volume of the reagent.