I am studying the design of cryopreservation scaffold using poly (3-hydroxybutyrate- 3-hydroxyhexanoate) copolymer (PHBH) fiber.
Currently, many researchers research on regenerative medicine using stem cells such as iPS cells and ES cells is extensively studied . There is a process of long-term storage and transport of stem cells, and it is necessary to cryopreserve cells when storing or transporting them.
As a method of cryopreserving cells that have been done until now, vitrification method and slow freezing method can be mentioned. For these cryopreservation methods, cells are freezed the cultured once after detaching them.
Peeling the cells causes stress on the cells, which reduces the survival rate of the cells. Furthermore, there is a problem that it takes time to wait for culturing again and growing cells after thawing.Therefore, in order to solve these problems, development of a scaffold that can be directly frozen is required.
In this research, we focused on nanofibers as a scaffolding material that enables direct freezing.
Nanofibers are made of polymer solution by electrospinning. The electrospinning method is a method of manufacturing a fiber by applying a voltage and pulling a polymer solution.
As the polymer physical properties which is a constituent of fiber when freezing, the glass transition temperature is important.
When cells are frozen, the cells contract. If the glass transition temperature of the polymer is higher than the freezing temperature, the cells will peel off as there is no flexibility during freezing. On the other hand, if the glass transition temperature is lower than the freezing temperature, the fiber is flexible so it can reduce the shrinkage stress on the cell when frozen. Especially by using nanofibers, this effect is expected because it is rich in flexibility.
PHBH was used as a scaffold for cells this time. PHBH is a random copolymer of hydroxybutyric acid and hydroxyhexanoic acid. PHBH has bioabsorbability, the glass transition temperature is close to 0 ° C and the freezing temperature. Because Tg is low, PHBH is flexible at freezing and thawing, so it is expected that the shrinkage stress of fiber on the cell will be tolerated.Also we expect that inflammation is also low due to the relatively low acid dissociation constant of degradation products.
So, I do direct cryopreservation by using PHBH scaffold.
Currently, many researchers research on regenerative medicine using stem cells such as iPS cells and ES cells is extensively studied . There is a process of long-term storage and transport of stem cells, and it is necessary to cryopreserve cells when storing or transporting them.
As a method of cryopreserving cells that have been done until now, vitrification method and slow freezing method can be mentioned. For these cryopreservation methods, cells are freezed the cultured once after detaching them.
Peeling the cells causes stress on the cells, which reduces the survival rate of the cells. Furthermore, there is a problem that it takes time to wait for culturing again and growing cells after thawing.Therefore, in order to solve these problems, development of a scaffold that can be directly frozen is required.
In this research, we focused on nanofibers as a scaffolding material that enables direct freezing.
Nanofibers are made of polymer solution by electrospinning. The electrospinning method is a method of manufacturing a fiber by applying a voltage and pulling a polymer solution.
As the polymer physical properties which is a constituent of fiber when freezing, the glass transition temperature is important.
When cells are frozen, the cells contract. If the glass transition temperature of the polymer is higher than the freezing temperature, the cells will peel off as there is no flexibility during freezing. On the other hand, if the glass transition temperature is lower than the freezing temperature, the fiber is flexible so it can reduce the shrinkage stress on the cell when frozen. Especially by using nanofibers, this effect is expected because it is rich in flexibility.
PHBH was used as a scaffold for cells this time. PHBH is a random copolymer of hydroxybutyric acid and hydroxyhexanoic acid. PHBH has bioabsorbability, the glass transition temperature is close to 0 ° C and the freezing temperature. Because Tg is low, PHBH is flexible at freezing and thawing, so it is expected that the shrinkage stress of fiber on the cell will be tolerated.Also we expect that inflammation is also low due to the relatively low acid dissociation constant of degradation products.
So, I do direct cryopreservation by using PHBH scaffold.