JP2014023541A - Atmosphere-regulating agent and method for culturing cell by using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the migration of an aldehyde to a medium, and to reduce the influence to cell culture.SOLUTION: The method for culturing cells comprises the step of placing a culture container housing an atmosphere-regulating agent containing an organic material as a main agent, an aldehyde-removing agent, the cells and the medium in a gas-barrier sealed container, and culturing the cells by regulating the oxygen concentration and the carbon dioxide concentration in the sealed container so as to be 18% or less, and 2% to 10% respectively.

Description

  The present invention relates to a cell culture method using an atmosphere adjusting agent and an aldehyde removing agent.

In the culture of biological samples such as tissues and cells carried out in the research field or industrial field of living organisms, reproduction or biotechnology, a gas environment different from the atmospheric environment is required.
For example, when observing living cells continuously for a long time, it is necessary to keep the living cells in the culture solution constant at the normal culture temperature and also to keep the pH of the culture solution constant. At that time, for example, the condition for maintaining the pH of the bicarbonate buffer culture solution at the same pH 7.4 as the normal state of blood is that the atmospheric carbon dioxide concentration is about 5%.

  In addition, hypoxic culture of cells has attracted attention in many research fields. Specifically, by culturing cells in a hypoxic atmosphere similar to that in vivo, genes such as hypoxia inducing factor (HIF) related to biochemical reactions and angiogenesis similar to those in vivo are induced, Has been confirmed to promote the proliferation and differentiation of the. In addition, in an ischemia reperfusion experimental model that reproduces organ failure due to blood flow cessation, the mechanism in the cell is studied in detail by placing cells and tissues under anoxic for a certain period of time. Furthermore, in a drug sensitivity test using human cells, a drug metabolism test is carried out by creating a reducing atmosphere in the absence of oxygen.

In culturing such a biological sample, a predetermined gas environment is created using a CO ₂ incubator or a multi-gas incubator, and cell culture is performed in a normal culture vessel having air permeability. In this case, a multiwell plate, a flask, a petri dish, a chamber slide, a culture bag, or the like is generally used as the culture container.

  When handling multiple samples in parallel, there is always a risk of mixing different types of samples (cross-contamination: cross-contamination), but the risk of cross-contamination increases by having many samples coexist in the incubator. There are concerns. For this reason, an incubator having a plurality of sample chambers has been developed. However, since it is expensive, facilities that can be introduced are limited. In addition, the introduction of incubators may be restricted due to management problems of high-pressure gas.

  For the above reason, in order to form a predetermined gas environment, a method using an airtight container and an atmosphere adjusting agent put in the air in place of the incubator is also used. Conventionally, when an anaerobic / microaerobic culture is performed using an atmosphere adjusting agent, an atmosphere adjusting agent mainly composed of water and sodium borate has been frequently used. In recent years, the mainstream of atmosphere control agents has shifted to products based on ascorbic acid due to safety and operational certainty.

  An oxygen absorbent mainly composed of ascorbic acids can be obtained by mixing ascorbic acids with a metal salt, activated carbon and water as disclosed in Patent Document 1, for example. Further, as disclosed in Patent Document 2, it is possible to control the amount of carbon dioxide gas generated by mixing with an alkaline earth metal hydroxide, and hence the carbon dioxide concentration in a fixed volume container. As described in Patent Document 3, an atmosphere adjusting agent capable of forming appropriate oxygen and carbon dioxide gas concentrations has been developed and used depending on the target biological material.

  Atmosphere conditioners composed mainly of organic substances may generate a small amount of by-products during the reaction, and such by-products may affect growth depending on the species and conditions of use. There was concern about being there.

Japanese Patent Laid-Open No. 10-314581 JP-A-10-327845 JP 09-252766 A

  An object of the present invention is to provide a cell culture method that reduces the influence of by-products in order to solve the above-mentioned problems of the simple culture technique using the above-mentioned atmosphere control agent.

  As a result of extensive research, the present inventor found that aldehydes exist as substances actually produced as by-products, and the amount of aldehyde released is very small, but the aldehyde gradually migrates to the aqueous phase medium after exposure for several days. It was found that it is possible to suppress the transfer of aldehyde to the medium by simultaneously adding an aldehyde remover.

  That is, the present invention provides an atmosphere conditioner mainly composed of an organic substance, an aldehyde remover, and a culture vessel containing cells and a medium in a gas barrier closed vessel, and the oxygen concentration in the closed vessel is 18% or less, carbonic acid. A cell culturing method characterized by culturing cells at a gas concentration of 2% to 10%.

  In the cell culture method of the present invention, the organic substance is ascorbic acid, and an open container containing ion-exchanged water is further installed in a gas barrier sealed container, and the ion exchange is performed during the culture period. It is preferred that the concentration of aldehyde that migrates into water does not exceed 2.0 mg / L.

  According to the present invention, it has become possible to construct a cell culture environment in which the risk of cross-contamination is reduced even with a cell line that is highly sensitive to aldehyde, with inexpensive equipment.

  The atmospheric conditioner in the present invention is a specific range suitable for the growth of cells targeting the oxygen concentration and carbon dioxide concentration in the gas barrier closed container by chemically reacting with oxygen in the atmosphere, for example, oxygen concentration. The carbon dioxide gas concentration can be adjusted to 18% or less and 2% or more and 10% or less. The atmosphere conditioner of the present invention contains water, a porous carrier and a metal compound in addition to an organic substance which is a main component of the oxygen absorption reaction, and further, carbonate or alkaline earth metal hydroxide for the purpose of controlling the reaction field. Containing.

  As the main component of the oxygen absorption reaction, an organic substance having a carbon dioxide generating ability is used, and ascorbic acids are particularly effective.

  When ascorbic acid is used as the main agent, L-ascorbic acid, L-sodium ascorbate, calcium L-ascorbate, sodium D-iso-sodium ascorbate or a mixture thereof is used. These ascorbic acids are preferably used by impregnating a porous carrier such as activated carbon as an aqueous solution. As the concentration of the ascorbate aqueous solution is higher, the amount of the porous carrier used can be reduced. Therefore, the concentration of ascorbic acid is preferably as close to the saturation solubility as possible. Further, the amount of water necessary for the oxygen absorption reaction is sufficiently ensured by using an aqueous solution of ascorbic acids. For this reason, ascorbic acids are preferably highly soluble salts, specifically sodium L-ascorbate. When sodium L-ascorbate is used, the concentration of the aqueous solution is preferably 40 to 55% by weight.

  Examples of the porous carrier include activated carbon, diatomaceous earth, silica gel, zeolite, pearlite, calcium silicate, pumice, cellulose, activated clay, alumina, hydroxyapatite, porous resin, porous glass, and the like. When activated carbon is used, activated carbon produced by various production methods such as steam activation and carbon dioxide activation using sawdust, coal, coconut shell and the like as raw materials can be used. The activated carbon is preferably granular activated carbon because it is used as an ascorbic acid or the like as an aqueous solution supported on the activated carbon and filled in a small bag. The particle diameter of the granular activated carbon is preferably 0.1 mm to 2 mm, more preferably 0.5 to 1 mm. If the particle diameter of the granular activated carbon is finer than the above range, the fluidity of the atmosphere modifier becomes poor and automatic filling becomes difficult. In addition, if the particle size is too large, there are problems that the oxygen absorption performance is lowered, the package is broken, and the contents spill out.

  The atmosphere adjusting agent used in the cell culture method of the present invention is added with a metal compound having a catalytic action for the oxygen absorption reaction. As the metal compound, ferrous chloride, ferric chloride, ferrous sulfate, ferric sulfate, manganese chloride, zinc sulfate, copper sulfate, an anhydrous salt or hydrated salt of copper chloride is preferable. As for the compounding quantity of a metal compound, 5-20 weight part of metal compounds are preferable with respect to 100 weight part of ascorbic acids.

  In the atmosphere adjusting agent used in the cell culture method of the present invention, a carbonate for controlling the reaction field in the alkaline region can be added in order to rapidly advance the reaction. The carbonate is preferably a water-soluble carbonate such as sodium carbonate, sodium bicarbonate, sodium carbonate hydrate. As for the compounding quantity of carbonate, 10-30 weight part of carbonate is preferable with respect to 100 weight part of ascorbic acids.

  In the atmosphere adjusting agent used in the cell culture method of the present invention, an alkaline earth metal hydroxide may be used as a carbon dioxide absorbent instead of the above carbonate in order to control the carbon dioxide concentration. In particular, calcium hydroxide, magnesium hydroxide or a mixture thereof is preferably used. As the alkaline earth metal hydroxide, a powder having an average particle diameter of 1 to 100 μm is preferably used, and a powder having an average particle diameter of 2 to 50 μm is more preferably used. The blending amount of the alkaline earth metal hydroxide is required to be 5 to 25 parts by weight with respect to 100 parts by weight of the atmosphere modifier obtained by impregnating activated carbon with ascorbic acid, metal salt and water. When the amount is less than this amount, oxygen absorption and carbon dioxide generation are not performed rapidly. Moreover, when there are too many compounding quantities, a carbon dioxide gas density | concentration will become low too much, and it will lead to the fall of an oxygen absorption rate, and will require a lot of atmosphere regulators.

  These components are blended as solids or used as an aqueous solution and supported on a porous carrier such as activated carbon, diatomaceous earth, or zeolite. The latter form having the effect of resorbing released aldehyde is more preferably used.

  In addition, in order to suppress excessive heat generation of the atmosphere adjusting agent accompanying the progress of the oxygen absorption reaction, it is preferable to blend a thermoplastic resin granule with the atmosphere adjusting agent. The thermoplastic resin used preferably has a particle system of 1 to 500 μm, more preferably 10 to 300 μm. The softening point of the thermoplastic resin is preferably 90 to 125 ° C., and the type is not particularly limited, but polyethylene, polypropylene, ethylene-vinyl acetate copolymer, elastomer, or a mixture thereof can be used. Molecular weight polyethylene, polypropylene or a mixture thereof is preferably used. If the softening point is too low, the normal reaction of the atmosphere adjusting agent is inhibited. On the other hand, if the softening point is too high, excessive heat generation of the atmosphere adjusting agent cannot be suppressed.

These atmosphere adjusting agents are accommodated in a packaging material having air permeability. The breathable wrapping material only needs to be permeable to oxygen and carbon dioxide gas, and has a gas permeability of 300 mL / (h · m ² ) or more and a carbon dioxide gas permeability of 300 mL / (h · m ² ) or more. A material is preferred. As the packaging material, for example, paper, non-woven fabric, perforated film and laminates thereof are used.

  In order to maintain the function for a long period of time, the above-described atmosphere modifier package is stored in a gas-barrier container or bag before use, and is taken out from the gas-barrier container or bag before use.

  The aldehyde removing agent used in the cell culture method of the present invention is composed mainly of a compound that can react with aldehydes at room temperature. Examples of such compounds include amines, amides, imides, amino acids, hydrazine derivatives, peroxides, natural products having an aldehyde absorption ability such as mineral sepiolite, adsorbents such as activated carbon, and palladium. It is selected from metal catalysts, enzymes having aldehyde resolution, and the like, and these can be used alone or in combination. Of these, amines, hydrazine derivatives and the like are preferably used, and ethylene urea, sulfanilic acid, aminoguanidine and the like are particularly preferably used.

  In addition to the main agent, a porous carrier for supporting the main agent and a dispersant for improving fluidity may be added to the aldehyde removing agent as long as the reaction between the main agent and aldehydes is not hindered. The same porous carrier as that used for the atmosphere adjusting agent can be used, but activated carbon having an aldehyde adsorption ability is preferably used.

  As a method for introducing the aldehyde remover into the gas barrier closed container, in addition to a method of introducing the package filled with the aldehyde remover as a separate package from the atmosphere modifier, a method of directly blending in the atmosphere modifier, Any method may be selected which is supported on a porous carrier and mixed with an atmosphere adjusting agent. The amount of aldehyde removal agent required in the system varies depending on the shape, volume, and quantity of the target cells and culture vessel, but ion exchange accommodated in an open container installed in a gas barrier closed container. It is preferable to set the usage amount so that the concentration of aldehyde transferred to water during the culture period does not exceed 2.0 mg / L, preferably 1.6 mg / L.

  According to the cell culture method of the present invention, an aldehyde remover is bundled in advance in a gas barrier closed container, thereby avoiding adverse effects on cells by suppressing the transfer of by-product aldehydes to the medium. Can do.

  The gas barrier closed container used in the cell culturing method of the present invention prevents the flow of gas inside and outside thereof, and maintains the oxygen and carbon dioxide gas concentrations formed by the introduced atmosphere adjusting agent for a long period of time. A container made of glass, metal, polycarbonate or the like is often used, but a gas barrier film and a laminate thereof can also be used.

  The culture vessel used in the cell culturing method of the present invention is not particularly limited as long as air permeability to the outside of the vessel is ensured, and any volume, shape, material, etc. suitable for culture can be adopted. it can. Moreover, although the culture container which has a cover part is used preferably, it is necessary to ensure the air permeability with the outside of a container also in this case.

  There is no restriction | limiting in particular in the culture medium used with the cell culture method of this invention, Since what is generally used can be applied as it is, the culture medium suitable for the cell to culture | cultivate can be selected freely.

  The cell culturing method of the present invention includes a culture vessel containing cells and a medium, and an atmosphere conditioner and aldehyde remover mainly composed of an organic substance, or an atmosphere conditioner mainly composed of an organic substance containing an aldehyde remover and a gas barrier. This can be carried out by placing it in an airtight container, sealing it, and allowing the container to stand at a temperature suitable for cell culture. At this time, for the purpose of measuring the amount of aldehyde generated in the gas barrier sealed container, an open container containing ion-exchanged water may be installed in the sealed container. Examples of the open type container include a beaker, a flask and the like in addition to the culture container, and the culture container is preferably the same type as the culture container containing the cells and the medium.

  As a method for accommodating cells and culture medium in a culture container, a method of accommodating a culture medium in which cells are seeded in advance in a culture container or a method of seeding cells in a culture medium after storing only the culture medium in the culture container is used Any method can be employed depending on the type of cells and medium to be used.

  Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is not limited thereto.

In the following Examples, Comparative Examples, and Reference Examples, “cells”, “medium”, and “culture vessel” shown below were used.
1. Cells Human kidney-derived cells (Tig-3-20: Sold by Human Science Foundation Research Resource Bank resource number JCRB0506 lot number R034)
2. Medium MEM medium (product name: 11095-080 (MEM Earle's liquid) manufactured by GIBCO)
3. Cultivation container 60 mm diameter dish (Product name: IWAKI 3010-060 60 mm / Tissue Culture Dish manufactured by AGC Techno Glass)

Example 1
In 100 g of an aqueous solution of sodium L-ascorbate (concentration 45% by weight), 6 g of ferrous sulfate and heptahydrate and 0.3 g of ethylene urea as an aldehyde removing agent were dissolved, and the aqueous solution was made into granular activated carbon (average particle size 0.6 mm). ) After impregnating 60 g, 70 g of low molecular weight polyethylene and 20 g of sodium carbonate · 10 hydrate were added and mixed to obtain an oxygen absorption / carbon dioxide gas generator (A) containing an aldehyde remover.

  An oxygen-absorbing / carbon dioxide generating package (A ') in which 5 g of (A) was filled in a breathable sachet of 90 mm long by 55 mm wide laminated with perforated polyethylene film was blended with an aldehyde remover.

Oxygen absorption / carbon dioxide generating package (A ′) containing an aldehyde removing agent and human kidney-derived cells were seeded at a cell density of 1.0 × 10 ⁴ cells / mL or 5.0 × 10 ³ cells / mL. Two 60 mm diameter dishes each containing 5 mL of MEM medium supplemented with 10% fetal bovine serum (hereinafter referred to as FBS) were loaded together with two 60 mm diameter dishes containing 5 mL of ion-exchanged water into a 2500 mL polycarbonate gas barrier sealed container. After culturing at 37 ° C. for 3 days, the number of cells was measured, and the aldehyde concentration transferred to ion-exchanged water was determined by the MBTH method (3-methyl-2-benzothiazolinone hydrazone colorimetric method, Kyoritsu Riken Laboratories, Inc. Measurement was performed with a measuring reagent LR-FOR). The results are shown in Table 1 together with the oxygen concentration and carbon dioxide concentration in the sealed container after cell culture. From Table 1, it can be seen that the number of cells after culture increased more than 10 times.

(Example 2)
In 100 g of sodium L-ascorbate aqueous solution (concentration 45% by weight), 6 g of ferrous sulfate and heptahydrate and 20 g of sodium carbonate and 10 hydrate are dissolved, and the aqueous solution is made into 60 g of granular activated carbon (average particle size 0.6 mm). It was impregnated, and 70 g of low molecular weight polyethylene was added and mixed to obtain an oxygen absorbing / carbon dioxide generating agent (B).

  5 g of (B) was filled into a 90 mm long x 55 mm wide Japanese paper longitudinally breathable sachet laminated with a perforated polyethylene film to obtain an oxygen absorbing / carbon dioxide generating package (B ′).

  Aldenite (alkaline aldehyde adsorbent manufactured by Nippon Enviro Chemicals Co., Ltd.) 2.0g of commercially available lower aldehyde adsorbent, filled with perforated polyethylene film, filled into a breathable sachet of 90mm x 55mm in width to remove aldehyde Body (C).

Oxygen absorption / carbon dioxide generation package (B ′) and aldehyde removal package (C), and human kidney-derived cells at a cell density of 1.0 × 10 ⁴ cells / mL or 5.0 × 10 ³ cells / mL Two 60 mm-diameter dishes each containing 5 mL of 10% FBS-added MEM medium sowed together with two 60-mm diameter dishes containing 5 mL of ion-exchanged water were loaded into a 2500-mL polycarbonate gas barrier sealed container. After culturing at 37 ° C. for 3 days, the number of cells was measured, and the concentration of aldehyde transferred to ion-exchanged water was measured by the MBTH method. The results are shown in Table 1 together with the oxygen concentration and carbon dioxide concentration in the sealed container after cell culture. From Table 1, it can be seen that the number of cells after culture increased more than 10 times.

(Comparative Example 1)
An oxygen absorbing / carbon dioxide generating package (B ′) obtained by filling 5 g of the oxygen absorbing / carbon dioxide generating agent (B) obtained in Example 2 into a 90 mm × 55 mm wide Japanese paper breathable sachet laminated with a perforated polyethylene film. ).

Oxygen-absorbing / carbon dioxide generating package (B ′) and 5% 10% FBS-added MEM medium seeded with human kidney-derived cells at a cell density of 1.0 × 10 ⁴ cells / mL or 5.0 × 10 ³ cells / mL Two pieces each containing 60 mm diameter dishes were loaded together with two 60 mm diameter dishes containing 5 mL of ion exchange water into a polycarbonate gas barrier hermetically sealed container having a volume of 2500 mL. After culturing at 37 ° C. for 3 days, the number of cells was measured, and the concentration of aldehyde transferred to ion-exchanged water was measured by the MBTH method. The results are shown in Table 1 together with the oxygen concentration and carbon dioxide concentration in the sealed container after cell culture. As a result of culturing the cells without using an aldehyde remover, the increase in the number of cells remained about 2 to 5 times.

(Reference Example 1)
Two 60 mm diameter dishes each containing 5 mL of 10% FBS-added MEM medium seeded with human kidney-derived cells at a cell density of 1.0 × 10 ⁴ cells / mL or 5.0 × 10 ³ cells / mL were added to 5 mL of ion-exchanged water. The sample was loaded into a multi-gas incubator set to oxygen 18% carbon dioxide gas 5% together with two 60 mm diameter dishes and cultured for 3 days at 37 ° C., and the number of cells was counted. The results are listed in Table 1. As a result of culturing cells using a multi-gas incubator without using an oxygen absorption / carbon dioxide generating package that is an aldehyde generation source, the number of cells was about the same as in Examples 1 and 2 combined with an aldehyde remover. An increase was seen.

  The cell culture method of the present invention using an organic substance-based atmosphere modifier and an aldehyde remover in combination is a simple and economical cell culture method capable of obtaining the same cell culture results as when a multi-gas incubator is used. It is.

Claims (3)

  A culture vessel containing an atmosphere conditioner mainly composed of organic substances, an aldehyde removing agent, cells and a medium is placed in a gas barrier sealed container, and the oxygen concentration in the sealed container is 18% or less and the carbon dioxide gas concentration is 2%. A cell culture method comprising culturing cells at 10% or less.   The cell culture method according to claim 1, wherein the organic substance is ascorbic acid.   An open container containing ion-exchanged water is further installed in the gas barrier closed container, and the concentration of aldehyde transferred to the ion-exchanged water during the culture period does not exceed 2.0 mg / L. 2. The cell culture method according to 2.