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Porcine islet isolation, cellular composition and secretory response
N J Crowther1, C F Gotfredsen, A J Moody
1Biochemistry Department, University of Sussex, Brighton, England.
Hormone and Metabolic Research = Hormon- Und Stoffwechselforschung = Hormones Et Metabolisme
|November 1, 1989
Summary
This study details porcine islet isolation and characterization, finding freshly isolated islets respond to glucose, but cultured islets do not. This highlights the importance of islet preparation for diabetes research.
Area of Science:
- Endocrinology
- Islet Biology
- Comparative Pancreatic Anatomy
Background:
- Porcine islets are a potential source for islet transplantation in diabetes treatment.
- Understanding porcine islet structure and function is crucial for successful xenotransplantation.
- Previous studies have focused on isolation techniques, but functional responses require further investigation.
Purpose of the Study:
- To isolate and purify porcine islets using collagenase digestion and ficoll gradient centrifugation.
- To compare the histological characteristics and hormone distribution of porcine islets with rat islets.
- To assess the glucose-stimulated insulin secretion (GSIS) of freshly isolated and cultured porcine islets.
Main Methods:
- Porcine pancreata were processed using collagenase infusion and static incubation.
- Islets were purified via filtration and ficoll gradient centrifugation.
- Insulin, glucagon, and somatostatin levels were quantified using radioimmunoassay (RIA).
- GSIS was evaluated by exposing islets to varying glucose concentrations (2.8 mM to 22.2 mM).
Main Results:
- High purity of isolated porcine islets was confirmed by insulin:amylase ratios.
- Porcine islets were smaller and less defined than rat islets, with acinar infiltration.
- Ratio of insulin:glucagon:somatostatin in islets was 105.1:0.68:0.087, differing from intact pancreas (105.1:5.8:1).
- Freshly isolated islets showed significant GSIS (1.8-2.3 fold increase), while cultured islets did not.
Conclusions:
- Porcine islet isolation yields high purity but may result in hormone loss, particularly glucagon and somatostatin.
- Structural differences exist between porcine and rat islets, with potential implications for xenotransplantation.
- Freshly isolated porcine islets exhibit robust GSIS, but this function is impaired after overnight culture, suggesting sensitivity to culture conditions.