Cryopreservation of Skin Tissues for Skin Grafts

Preservation of living tissue and organs are very important to ensure successful transplantation. The storage of living tissue, from the time of removal of the donor tissue until transplantation, is one of the most important factors for successful tissue transplantation. The purpose of living tissue storage is to maintain the viability of the mammalian cells, and various methods have been developed to lengthen the time donor tissue can be stored without loss of cell integrity. At present, low temperature is used as the major organ preservation method. Generally, cells are preserved in a frozen state at -196°C (1-3). The survival rate after such storage has been enhanced by controlled temperature freezing. However, cell survival after freezing can be low (namely, 20~40%), as with ES cells (embryonic stem cells),EG cells (embryonic genital cells) and induced pluripotent stem (iPS) cells. It would be of great advantage to researchers in the field of stem cell research to be able to preserve these cells more successfully. It would also be of benefit to be able to preserve other cells, such as platelets, over the long term without freezing. Likewise, research continues in our attempts to prolong the time for transplantation of solid organs, and in the development of optimal perfusion fluids that protect against ischemia remains an active subject of investigation. Various storage solutions for organ preservation, such as the UW solution developed at the University of Wisconsin (USA) are also in current clinical use. However, it is necessary to develop storage solutions that can maintain the viability of tissues and organs for longer periods because of the limitations of storage in UW solution. After transplantation, many organs suffer from the generation of free radicals following reperfusion. The restoration of blood flow becomes a trigger for injury, with subsequent lipid peroxidation of the biomembrane leading to membrane failure and as a result, the transplanted organ fails. A logical goal would then be the development of a preservation fluid that would limit cell damage by preventing peroxylipid generation. Such a preservation fluid should limit cell division and multiplication. A room temperature storage state could also potentially prevent the injury to the small vessel endothelium seen with freezing and to delicate tissues, such as the cornea, which do not survive freezing well. Although these tissues can be held from 4 to 24 hours at 4oC, large organs impose a severe