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Cell microencapsulation technology involves immobilization of the cells within a polymeric semi-permeable membrane that permits the bidirectional diffusion of molecules such as the influx of oxygen, nutrients, growth factors etc. essential for cell metabolism and the outward diffusion of waste products and therapeutic proteins. At the same time, the semi-permeable nature of the membrane prevents immune cells and antibodies from destroying the encapsulated cells regarding them as foreign invaders. The main motive of cell encapsulation technology is to overcome the existing problem of graft rejection in tissue engineering applications and thus reduce the need for long-term use of immunosuppressive drugs after an organ transplant to control side effects. == History == In 1933 Vincenzo Bisceglie made the first attempt to encapsulate cells in polymer membranes. He demonstrated that tumor cells in a polymer structure transplanted into pig abdominal cavity remained viable for a long period without being rejected by the immune system. Thirty years later in 1964, the idea of encapsulating cells within ultra thin polymer membrane microcapsules so as to provide immunoprotection to the cells was then proposed by Thomas Chang who introduced the term "artificial cells" to define this concept of bioencapsulation. He suggested that these artificial cells produced by a drop method not only protected the encapsulated cells from immunorejection but also provided a high surface-to-volume relationship enabling good mass transfer of oxygen and nutrients. Twenty years later, this approach was successfully put into practice in small animal models when alginate-polylysine-alginate (APA) microcapsules immobilizing xenograft islet cells were developed. The study demonstrated that when these microencapsulated islets were implanted into diabetic rats, the cells remained viable and controlled glucose levels for several weeks. Human trials utilising encapsulated cells were performed in 1998. Encapsulated cells expressing a cytochrome P450 enzyme to locally activate an anti-tumour prodrug were used in a trial for advanced, non-resectable pancreatic cancer. Approximately a doubling of survival time compared to historic controls was demonstrated. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Cell encapsulation」の詳細全文を読む スポンサード リンク
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