| Summary: | 碩士 === 國立屏東科技大學 === 獸醫學系所 === 97 === Diabetes mellitus(DM) type 1 accounts for approximately 10% of all diabetic cases worldwide and is characterized by an absolute insulin deficiency. Insulin injection therapy as a treatment for type 1 diabetic patient is lifesaving, but it cannot avoid the development of complications of the eyes、 kidney、nerve and the cardiaovascular system. Microencapsulation of isolated islets is a good method for providing protection against immunologic reactions to the cells in both allogeneic and xenogenic. Since islet transplantation has become an option for the treatment of typeΙinsulin-dependent DM, several methods of isolation, purification and cryopreservation of islets of Langerhans have been developed. Cryopreservation procedures have been established as a useful long-term storage strategy. Moreover, they can be used to supplement fresh isolated and/or cultured islets to increase the β-cell mass in order to improve islet graft function following transplantation. Islet transplantation is a promising method of providing tight glycemic control for patient with DM. However ,a number of obstacles currently prevent islet transplantation from becoming routine clinical reality. Microencapsulation is a technique that enables the transplantation of pancreatic islets in the absence of immunosuppression by protecting the islet tissue through a mechanical barrier. This protection may even allow for the transplantation of animal tissue, which opens the perspective of using animal donors as a means to solve the problem of organ shortage. Microencapsulation is not yet applied in clinical practice, mainly because encapsulated islet graft survival is limited. One important observation showed that there is a gradual decrease in islet function, a gradual increase in central necrosis, a continuous increased replication of islet cells, and a nonprogressive overgrowth of a portion of the microencapsulated islet graft. Three important aspects of the microencapsulated islet graft technique may be associated with these phenomena. The first is related to the biocompatibility of the graft. A number of microcapsules lack biocompatibility, which explains the occurrence of overgrowth. The second is related to the immunoprotective properties of the microcapsules. Immunoprotection is incomplete because capsules may allow the passage of small proinflammatory factors, which lead to cell death and dysfunction.
The third factor is related to the great distance between the encapsulated islets and the blood supply. An important consequence of the great diffusion distance is the limited supply of oxygen, which leads to hypoxia, causes islet dysfunction and necrosis.
In this experiment we compare four methods that could induce diabetes and use nano-material as the barrier that we hope reserving those advantages and resolve some obstacles in microencapsulated graft.
Alloxon 80mg/kg I.V. was the best way in induction success rate and patients safty in dogs in this experiment. After the dogs were induced to be diabetes that we implanted calcium phosphate cement(CPC) packaged Insulinoma cells chambers to control the patient’s blood glucose level and make it obviously improved and watching the persistence of function.
|
|---|
