Islet cell isolation in experimental d,l-ethionine pancreatitis in dogs

Cellular proliferation in the canine pancreas after d,l-ethionine dosage as detected by double immunohistochemical labelling

d,l-Ethionine produces pancreatic exocrine necrosis and islet proliferation in hamsters and dogs. As a first step in examining whether induction of islet proliferation has therapeutic applications in animals with exhausted or destroyed insulin-producing beta-cells, we studied pancreatic cellular proliferation after intravenous administration of d,l-ethionine in normal dogs. Double immunohistochemical labelling of pancreatic tissue was used to identify proliferating cells in three groups of six clinically normal crossbred dogs administered d,l-ethionine (100 mg/kg) intravenously three times a week for two weeks. Six additional dogs served as untreated controls. Group I was euthanased and necropsied on day 15 (72 hours after the final dose of ethionine). Groups II and III were euthanased on days 29 and 43 respectively. Utilising markers for proliferating nuclei, insulin and cytokeratin, proliferating cells were classified as acinar, endocrine (both intra or extra-islet), duct or 'other' (i.e. infiltrative or interstitial) and counted under the light microscope (40x magnification). Compared to controls, an increase in the number of proliferating cells was found in all categories except ducts. Acinar cells demonstrated statistically significant (p < 0.05) proliferation, greatest two weeks after ethionine cessation continuing over four weeks. The interstitial, infiltrative or 'other' group also showed proliferation, however this was a more immediate response, which substantially decreased two weeks after ethionine administration. Endocrine cells showed only minor and non-significant proliferative activity and were probably not responsible for a significant increase in apparent beta-cell mass. The number of proliferating duct cells was inconsequential and there appeared to be no specific relationship between any cell populations and duct cells.

Effect of d,l-ethionine administration on the histomorphology of canine pancreatic acinar and beta-cells

d,l-Ethionine produces pancreatic exocrine necrosis and islet proliferation in hamsters and dogs. As a first step in examining whether induction of islet proliferation has therapeutic applications in animals with exhausted or destroyed insulin-producing beta-cells, we studied pancreatic pathological alterations after intravenous administration of d,l-ethionine in normal dogs. Histomorphological changes in pancreatic acinar cells and beta-cells were assessed in three groups of six clinically normal crossbred dogs administered d,l-ethionine (100 mg/ kg) intravenously three times a week for two weeks. Six additional dogs served as untreated controls. Group I was euthanased and necropsied on day 15 (72 hours after the final dose of ethionine). Groups II and III were euthanased on days 29 and 43 respectively. Severe acinar destruction occurred resulting in significant (p < 0.001) shrinkage of the pancreas in all groups. Although there was variability in histomorphology within groups, pancreases of group I generally exhibited widespread loss of pancreatic acinar structure. Remaining acinar cells were difficult to discern from other cell types within lobules and were surrounded by infiltrates, predominantly of lymphocytes. Partial acinar cellular regeneration had occurred by day 29, but was still incomplete at day 43. Immunohistochemistry suggested that the effect of d,l-ethionine administration on the histomorphology of beta-cells in the left lobe was minimal; however, morphometry demonstrated a significant (p < 0.05) increase in the number of individual beta-cells in groups II and III, and clusters of 2-10, 10-20 and 20+ cells in Group II. It is probable that the apparent increase in the number of individual and other beta-cell arrangements observed in some groups resulted primarily from alterations in the exocrine tissue, although some beta-cell hyperplasia cannot be excluded completely.