Experience of islet isolation without neutral protease supplementation

Area of Science:

• Islet isolation and transplantation
• Digestive enzyme applications in tissue processing

Background:

• A novel islet isolation protocol uses collagenase with neutral protease (NP) during digestion.
• Variations in digestion progression led to 10 cases where NP was not required (no-NP group) out of 94 isolations.
• The remaining 84 isolations used NP (control group).

Purpose of the Study:

• To evaluate the necessity of neutral protease (NP) supplementation in islet isolation protocols.
• To compare islet isolation outcomes between protocols with and without NP.

Main Methods:

• Compared 10 islet isolations without NP (no-NP group) to 84 isolations with NP (control group).
• Pancreata were digested using a similar collagenase dose in both groups.
• Assessed digestion time, trapped islets, islet yield, and clinical transplantation outcomes.

Main Results:

• The no-NP group exhibited significantly shorter digestion times (15.0±1.8 vs 19.5±0.6 min) and fewer trapped islets (10.9±2.8% vs 28.1±2.4%).
• Post-purification islet yield was comparable between groups (355±45 x10^3 vs 318±17 x10^3 IE).
• Five no-NP preparations resulted in a 64.3±15.2% reduction in insulin usage post-transplantation, despite longer cold ischemia times (10.3±0.9 vs 7.9±0.4 h).

Conclusions:

• Neutral protease supplementation is not consistently necessary for effective islet isolation.
• Shorter digestion times and reduced islet trapping were observed without NP.
• Further evaluation of cold ischemia time and NP contamination is recommended for optimizing NP dosage.