Morphological changes in pancreatic fragments prepared for transplantation by collagenase treatment.

Canine pancreases were excised, minced, mechanically chopped, and incubated with collagenase in a manner similar to that used routinely in the preparation of mixed-cell pancreatic autografts. The resultant pancreatic fragments were studied by light and electron microscopy after various periods of collagenase incubation. As a control, pancreatic tissue was studied immediately after organ excision, immediately before addition of collagenase, and after various periods of incubation in balanced salt solution without collagenase. The mincing and chopping procedures alone induced a large population of highly aberrant, severely vacuolated acinar cells within the fragments. This vacuolation was caused by massive dilation of the cisternae of the rough endoplasmic reticulum. Subsequent incubation in collagenase solution, which appeared to destroy the aberrant cells in a selective manner, led to a remnant population with much improved acinar cell morphology. Incubation in balanced salt solution without collagenase resulted in a progressive increase in vacuolated cell incidence until abnormal pancreatic acinar cells dominated the tissue. The findings suggest that collagenase treatment may facilitate mixed-cell pancreatic transplantation by culling degenerative acinar cells from the grafted cell population, thereby reducing the likelihood of autodigestion at the transplant site. The extensive acinar cell destruction mediated by the collagenase may also be responsible for the release of a previously described hypotensive factor (pancreatic shock factor) into the graft infusion.