The main advantage of cell therapy is the possibility to immune-isolate the graft in a device to avoid immune suppressive regimen. In islet transplantation field, bioartificial pancreas is under development to restore normoglycaemia in diabetic patients. Yet, to be able to reach insulin independence a certain amount of islets is needed. The fact that they are confined in a restricted area might have deleterious effect on their survival. The aim of this work was to determine the effect of islet density on survival in a definite area, under oxygen pressure around 2% close to the in vivo conditions and to improve islet survival using perfluorocarbons combined with adenosine.

After isolation, rat islets were cultured at different densities (150; 300; 600IEQ/cm²) under normoxia (21%O2) and hypoxia conditions (2%O2) in presence or absence of perfluorocarbons (10%) with adenosine (1mM). After 24h in culture, islet viability (FDA/Pi), functionality (GSIS index, ATP levels) and expression of hypoxia (HIF-1α) were assessed.

Increase in islet density led to a drop in ATP levels in normoxia (300IEQ/cm²: 0.90±0.17; 600 IEQ/cm²: 1.14±0.41 vs cnt: 1.58±0.19; n=9 p<0.05), which was worsened under hypoxia (300IEQ/cm²: 0.60±0.08; 600 IEQ/cm²: 0.65±0.10 vs cnt: 0.93±0.12; n=9 p<0.05). Medium supplemented with perfluorocarbons and adenosine counteract hypoxia with a restoration of ATP levels (150IEQ/cm²: 2.98±0.44; 300 IEQ/cm²: 1.90±0.16; 600 IEQ/cm²:1.75±0.21; n=9 p<0.05).

HIF-1α mRNA levels increased with density in normoxia (300IEQ/cm²: 1.07±0.13; 600IEQ/cm²: 1.01±0.14) as compared to control (0.91±0.03, n=9, p<0.05), and under hypoxia (300IEQ/cm²: 1.47±0.07; 600IEQ/cm²: 1.73±0.06 vs cnt: 0.94±0.09). The presence of perfluorocarbons and adenosine decrease the HIF-1α mRNA levels under hypoxia (150IEQ/cm²: 0.62±0.04; 300 IEQ/cm²: 0.37±0.09; 600 IEQ/cm²: 0.79±0.08; n=9 p<0.05). Increase in cell density was also correlated to a decrease in cell function in normoxia (300IEQ/cm²: 3.28±0.93; 600IEQ/cm²: 2.03±0.87 vs. cnt 4.61±0.99; n=9) and loss of cell function under hypoxia (300IEQ/cm²: 0.99±0.09; 600IEQ/cm²: 0.48±0.08 vs. cnt 1.30±0.16; n=9,). Function was improved by perfluorocarbons and adenosine under hypoxia (150IEQ/cm²: 1.95±0.31; 300 IEQ/cm²: 0.94±0.18; 600 IEQ/cm²: 1.10±0.20; n=9 p<0.05).

This study showed that the use of perfluorocarbons, and adenosine improve oxygenation of islets in a hypoxic and confined environment after 24 hours in culture. The use of such supplement in the bioartificial pancreas could implement diabetes reversion.

« Back to 2015 American Transplant Congress