Experience with pancreas islets separation, immunoisolation and cryopreservation

Area of Science:

• * Transplantation immunology
• * Biomedical engineering
• * Islet cell biology

Background:

• * Pancreas islet isolation and preservation are critical for transplantation and research.
• * Current methods for islet isolation, identification, and cryopreservation require optimization.
• * Biocompatibility of materials used in islet encapsulation and long-term storage needs evaluation.

Purpose of the Study:

• * To enhance methods for digesting rat, human, and pig pancreases for islet isolation.
• * To develop and assess immunoisolation techniques for pancreatic islets.
• * To evaluate the biocompatibility of hollow fibers for islet encapsulation.
• * To compare the efficacy of different cryopreservation methods for pancreatic islets.

Main Methods:

• * Improved pancreas digestion and Langerhans islet identification using intravenous I-DTZ injection.
• * Development of two immunoisolation methods: modified Sun method (alginate/polyethyleneimine/protamine/heparin) and Zekorn method (microcapsules).
• * In vitro biocompatibility assessment of polypropylene (PP), surface-modified PP (PPS), and polysulphone (PS) hollow fibers.
• * Comparison of three islet cryopreservation techniques: semicontrollable freezing, programmable Kriomedpol machine freezing, and vitrification.

Main Results:

• * Enhanced digestion and identification of pancreatic islets were achieved.
• * Two novel immunoisolation methods for islets were successfully developed.
• * Polysulphone (PS) hollow fibers demonstrated full biocompatibility in vitro; PP and PPS were not fully compatible.
• * Exocrine tissue presence did not affect in vitro insulin secretion if the alginate matrix remained gelled.
• * The Kriomedpol machine yielded the highest percentage of viable frozen/thawed islets and the most reliable results compared to other cryopreservation methods.

Conclusions:

• * Optimized methods for pancreatic islet isolation and identification enhance research capabilities.
• * Polysulphone hollow fibers are suitable for islet encapsulation, while PP and PPS require further modification.
• * The Kriomedpol method is superior for cryopreserving pancreatic islets, ensuring higher cell viability and reliable outcomes for transplantation or research.