Method for mass retrieval, morphologic, and functional characterization of adult porcine islets of Langerhans: a potential nonhuman pancreatic tissue resource for xenotransplantation in insulin-dependent diabetes mellitus.

BACKGROUND: We aimed to implement and expand an original technique for mass procurement, maintenance, and study of adult porcine pancreatic islets (PPIs), which had been previously developed in our laboratory. METHODS: By screening through specific criteria for pig donor strain selection, we acquired new leads for separation of large, intact islets from the whole pancreas. Accomplishment of this goal also was permitted by adjusting, and or replacing physical/chemical parameters of the pancreatic digestion process. RESULTS: High yield isolation and purification of large and intact PPIs was thoroughly associated with full retention of islet morphologic integrity, as proven by accurate assessment of islet cell structure and ultra-structure, as well as viability and functional competence, in vitro and in vivo. In particular, we observed that isolated PPIs may retain capability of synthesizing insulin "de novo," and regulate this property on glucose stimulation. We also began to explore new approaches for in vitro, long-term PPI culture maintenance. CONCLUSION: We found that a graft of PPI containing algin/polyaminoacidic microcapsules, in nonimmunosuppressed diabetic rodents, was associated preliminary with remission of hyperglycemia, providing further insight into the physiologic competence of these islets.

Ultrastructural examination of pancreatic islet containing alginate/polyaminoacidic coherent microcapsules.

We ultrastructurally examined pancreatic islet containing alginate/poly-L-ornithine (AG/PLO) coherent microcapsules (CM) which we had previously developed in our laboratory. Specific issues, such as extent of CM coherency as well as morphologic integrity, and viability of the encapsulated islet subcellular organelles were addressed. We preliminarily demonstrated, both at scanning (SEM) and transmission (TEM) electron microscopy analysis, that CM seem to provide for structurally intact and functional, artificial microbarriers, enveloping each individual islet. These findings, additional to CM immunobarrier competence and biocompatibility, previously shown by our studies, might foster progress of CM into islet graft immunoisolation experimental and ultimately clinical trials.