Culture prior to transplantation preserves the ultrastructural integrity of monkey pancreatic islets

Abstract

Transplantation of pancreatic islets represents a promising way of curing type I diabetes (insulin-dependent diabetes mellitus). Culture enables the survival of endocrine tissue awaiting islet transplantation and reduces islet immunogenicity prior to xenografting. In this study, attempts were made to preserve the monkey islets in culture for 7 days and to study the ultrastructure by electron microscopy. The islets were isolated from monkey pancreas by the collagenase digestion method and were separated from acinar cells by dextran density gradient centrifugation. These islets were preserved in a humidified atmosphere of 5% carbon dioxide and 95% air for 7 days. The culture medium used was CMRL-1066. After 7 days of culture the islets were processed for light and electron microscopic studies, which revealed that the cultured islets were intact and maintained their structural integrity. Semi-thin sections of the cultured islets showed morphology with occasional structural alterations at the periphery. Dithizone staining of the cultured islets showed crimson red colour, proving that the islets were pure and without any exocrine contamination. Electron microscopy showed that the cultured islets had well-preserved alpha-, beta- and delta-cells. Different cell types of the monkey pancreatic islets were identified by the presence of their characteristic secretory granules. The ultrastructural characteristics present in hormone-synthesizing cells, i.e. rough-endoplasmic reticulum, Golgi apparatus, mitochondria and secretory granules, were observed as in native islets.

Normal hematological indices, blood chemistry and histology and ultrastructure of pancreatic islets in the wild Indian bonnet monkeys (Macaca radiata radiata)

“…Our study shows the maximum length and breadth of islets to range from 47.97 to 304.41 and 41.12 to 195.4 microns respectively. An earlier report from our laboratory had described the maximum diameter of monkey pancreatic islets as 233 microns [3]. Probably these values are comparable.…”

Towards xenotransplantation of pig islets in the clinic

“…In the case of islets it is important that no residual exocrine tissue be present as local reaction to pancreatic enzymes can be expected. This is more difficult in the pig than in humans [25] and prolonged culture in vivo may be required [26].…”

Effect of short-term culture on functional and stress-related parameters in isolated human islets

“…Cultured islets have been shown to have immunologic advantages compared with freshly isolated islets [9][10][11]. Ultrastructural integrity of human and monkey islets was shown to be maintained during culture for 1 week [12,13]. With respect to postgraft function, it has been shown that rat islets cultured for 1 week were not less effective than the fresh islets when assessed by transplantation into isogeneic Keywords culture, function, islet, stress, transplantation.…”