Alginate Microencapsulation of Human Islets Does Not Increase Susceptibility to Acute Hypoxia

Abstract EN

Islet transplantation in diabetes is hampered by the need of life-long immunosuppression.

Encapsulation provides partial immunoprotection but could possibly limit oxygen supply, a factor that may enhance hypoxia-induced beta cell death in the early posttransplantation period.

Here we tested susceptibility of alginate microencapsulated human islets to experimental hypoxia (0.1–0.3% O2 for 8 h, followed by reoxygenation) on viability and functional parameters.

Hypoxia reduced viability as measured by MTT by 33.8±3.5% in encapsulated and 42.9±5.2% in nonencapsulated islets (P<0.2).

Nonencapsulated islets released 37.7% (median) more HMGB1 compared to encapsulated islets after hypoxic culture conditions (P<0.001).

Glucose-induced insulin release was marginally affected by hypoxia.

Basal oxygen consumption was equally reduced in encapsulated and nonencapsulated islets, by 22.0±6.1% versus 24.8±5.7%.

Among 27 tested cytokines/chemokines, hypoxia increased the secretion of IL-6 and IL-8/CXCL8 in both groups of islets, whereas an increase of MCP-1/CCL2 was seen only with nonencapsulated islets.

Conclusion.

Alginate microencapsulation of human islets does not increase susceptibility to acute hypoxia.

This is a positive finding in relation to potential use of encapsulation for islet transplantation.