Xenotransplantation of islets of Langerhans

Islet concept

 

 

 

 

The pancreas is divided into exocrine part and endocrine part. The exocrine part accounts for about 90% of the pancreas, which is mainly composed of acini and ductal system, and mainly secretes pancreatic juice; the endocrine part is also called islet, which is an endocrine cell mass with different size and shape scattered among the acini of exocrine part, which accounts for about 1.5% of the volume of pancreas, mainly distributed in the tail of pancreas. The islet is a cell mass composed of several to hundreds of cells.

 

Islet cells can be divided into a cell, B cell, D cell, PP cell and so on. A cells account for 20% of the total islet cells, mainly distributed in the peripheral part of the islet, secreting glucagon; B cells are the main cells of the islet, accounting for 60% of the total islet cells~ 70%, mainly in the center of the islet, B cells mainly secrete insulin, so it is also called insulin cells; D cells are less, accounting for about 5% of the islet cells, which are scattered between a and B cells of the islet, mainly secreting growth hormone releasing inhibiting hormone.

 

 

 

 

 

 

Xenogeneic islets are non-human islets, which mainly refer to the islets of pigs. The World Health Organization and the International Association for xenotransplantation (IXA) have emphasized that at present, only pigs can be used as xenogeneic donors. Because the structure of insulin between human and pig is very similar, there is only one amino acid difference, that is, the 30th of B chain of human insulin is threonine, while that of pig is alanine, and pig's insulin is easy to obtain, so pig's insulin is widely used in clinical treatment of human diabetes (as early as the 1950s, it was used for diabetes treatment).