Oxygenation of the Intraportally Transplanted Pancreatic Islet

Abstract EN

Intraportal islet transplantation (IT) is not widely utilized as a treatment for type 1 diabetes.

Oxygenation of the intraportally transplanted islet has not been studied extensively.

We present a diffusion-reaction model that predicts the presence of an anoxic core and a larger partly functional core within intraportally transplanted islets.

Four variables were studied: islet diameter, islet fractional viability, external oxygen partial pressure (P) (in surrounding portal blood), and presence or absence of a thrombus on the islet surface.

Results indicate that an islet with average size and fractional viability exhibits an anoxic volume fraction (AVF) of 14% and a function loss of 72% at a low external P.

Thrombus formation increased AVF to 30% and function loss to 92%, suggesting that the effect of thrombosis may be substantial.

External P and islet diameter accounted for the greatest overall impact on AVF and loss of function.

At our institutions, large human alloislets (>200 μm diameter) account for ~20% of total islet number but ~70% of total islet volume; since most of the total transplanted islet volume is accounted for by large islets, most of the intraportal islet cells are likely to be anoxic and not fully functional.