P-203

Islet area fraction measurements in 236 porcine pancreas biopsies to identify suitable pigs for islet isolation

J. Abouaish¹, T. O'Brien², J. Parker², M. Graham¹, S. Soltani¹, G. Loganathan¹, B. Hering¹, A.N. Balamurugan^1
1 Schulze Diabetes Institute, Dept. of Surgery, University of Minnesota, Minneapolis, USA; ² Veterinary Population Medicine, Minneapolis, USA

Background: Donor variability contributes to much of the difficulty associated with porcine islet isolation. Question surrounding the number of islets present in a pancreas necessitates a reliable method for answering this basic question. Islet area fraction (IAF) scoring is a novel method for quantifying the number of islets in a pancreas and variability between pancreases.

Methods: Samples for IAF determinations were taken from three locations in young (<18 months) and adult (>18 months) porcine pancreases: the splenic, connecting and duodenal lobe. The samples were processed for immunohistochemical labeling for insulin. Using photomicroscopic images, IAF was calculated as islet/total area by tracing the perimeter of the tissue, excluding any voids within the tissue, and counting insulin positive pixels within the outlined region. Backward model selection method was used to select the best set of predictors of islet yields from parameters (islets >8000µm²/Unit Area, total islet area, number of islets >8000µm², IAF).

Results: In total, 236 porcine biopsy samples (multiple samples taken from 101 pigs) were analyzed using IAF scoring. The average IAF score was 0.87 ± 0.58% with a range of 0.01-3.96%. A statistical difference in average IAF score between all sample locations was measured (p<0.05): connecting (1.13 ± 0.52%, n=53), duodenal (0.87 ± 0.67%, n=54), splenic (0.68 ± 0.49%, n=101). There was no significant difference between IAF scores in young (0.87 ± 0.56%, range 0.09-3.96%, n=104) and adult pigs (0.91 ± 0.61%, range 0.03-3.12%, n=116, p=0.58). Pig IAF scores were comparable with human IAF scores (1.60 ± 0.49%, n=4). IAF scores did not strongly correlate with islet yields but was the best predictor of islet yield.

Conclusion: Young and adult porcine pancreases contain comparable proportions of islets to humans. Therefore, it is possible to get higher islet yields in pigs than humans if islet isolation methods are optimized.

P-203

Islet area fraction measurements in 236 porcine pancreas biopsies to identify suitable pigs for islet isolation

J. Abouaish¹, T. O'Brien², J. Parker², M. Graham¹, S. Soltani¹, G. Loganathan¹, B. Hering¹, A.N. Balamurugan^1
1 Schulze Diabetes Institute, Dept. of Surgery, University of Minnesota, Minneapolis, USA; ² Veterinary Population Medicine, Minneapolis, USA

Background: Donor variability contributes to much of the difficulty associated with porcine islet isolation. Question surrounding the number of islets present in a pancreas necessitates a reliable method for answering this basic question. Islet area fraction (IAF) scoring is a novel method for quantifying the number of islets in a pancreas and variability between pancreases.

Methods: Samples for IAF determinations were taken from three locations in young (<18 months) and adult (>18 months) porcine pancreases: the splenic, connecting and duodenal lobe. The samples were processed for immunohistochemical labeling for insulin. Using photomicroscopic images, IAF was calculated as islet/total area by tracing the perimeter of the tissue, excluding any voids within the tissue, and counting insulin positive pixels within the outlined region. Backward model selection method was used to select the best set of predictors of islet yields from parameters (islets >8000µm²/Unit Area, total islet area, number of islets >8000µm², IAF).

Results: In total, 236 porcine biopsy samples (multiple samples taken from 101 pigs) were analyzed using IAF scoring. The average IAF score was 0.87 ± 0.58% with a range of 0.01-3.96%. A statistical difference in average IAF score between all sample locations was measured (p<0.05): connecting (1.13 ± 0.52%, n=53), duodenal (0.87 ± 0.67%, n=54), splenic (0.68 ± 0.49%, n=101). There was no significant difference between IAF scores in young (0.87 ± 0.56%, range 0.09-3.96%, n=104) and adult pigs (0.91 ± 0.61%, range 0.03-3.12%, n=116, p=0.58). Pig IAF scores were comparable with human IAF scores (1.60 ± 0.49%, n=4). IAF scores did not strongly correlate with islet yields but was the best predictor of islet yield.

Conclusion: Young and adult porcine pancreases contain comparable proportions of islets to humans. Therefore, it is possible to get higher islet yields in pigs than humans if islet isolation methods are optimized.