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Cell loss in isolated human islets occurs by apoptosis
S Paraskevas1, D Maysinger, R Wang
1Department of Surgery, McGill University, and the Montreal General Hospital Research Institute, Quebec, Canada.
Pancreas
|April 15, 2000
Summary
Human islet isolation triggers programmed cell death (apoptosis) in beta cells, significantly increasing DNA fragmentation and transglutaminase activity. This beta cell loss after isolation may explain the failure of islet transplantation in humans.
Area of Science:
- Endocrinology
- Cell Biology
- Transplantation Immunology
Background:
- Purified islet allografts often fail in long-term glucose homeostasis for human recipients.
- Islet isolation procedures may remove crucial pancreatic elements supporting islet survival.
Purpose of the Study:
- To investigate if human islet isolation induces programmed cell death (apoptosis).
Main Methods:
- Human islets were isolated using Liberase or Collagenase P.
- Islets were cultured and examined daily for histology, hormone expression, DNA fragmentation (ELISA, TUNEL assay), and transglutaminase (TG) activity.
Main Results:
- Significant increases in TG activity (1,000%) and DNA fragmentation (1,890%) were observed post-isolation (p < 0.05).
- Histological and electron microscopy confirmed apoptotic bodies and pyknotic nuclei.
- TUNEL-positive cells, primarily insulin-immunoreactive cells, constituted 31.4% by day 5.
Conclusions:
- Apoptosis occurs rapidly in human islet cells, particularly beta cells, following isolation.
- This post-isolation beta cell loss is a potential factor in the limited success of islet transplantation.
- Further research is warranted to address beta cell mass reduction after isolation.