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Mathematical predictions of oxygen availability in micro‐ and macro‐encapsulated human and porcine pancreatic islets
Author(s) -
Cao Rui,
Avgoustiniatos Efstathios,
Papas Klearchos,
Vos Paul,
Lakey Jonathan R. T.
Publication year - 2020
Publication title -
journal of biomedical materials research part b: applied biomaterials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.665
H-Index - 108
eISSN - 1552-4981
pISSN - 1552-4973
DOI - 10.1002/jbm.b.34393
Subject(s) - islet , pancreatic islets , insulin , oxygen , secretion , endocrinology , chemistry , medicine , dna , biology , biochemistry , organic chemistry
Optimal function of immunoisolated islets requires adequate supply of oxygen to metabolically active insulin producing beta‐cells. Using mathematical modeling, we investigated the influence of the pO 2 on islet insulin secretory capacity and evaluated conditions that could lead to the development of tissue anoxia, modeled for a 300 μm islet in a 500 μm microcapsule or a 500 μm planar, slab‐shaped macrocapsule. The pO 2 was used to assess the part of islets that contributed to insulin secretion. Assuming a 500 μm macrocapsule with a 300 μm islet, with oxygen consumption rate (OCR) of 100–300 nmol min −1 mg −1 DNA, islets did not develop any necrotic core. The nonfunctional zone (with no insulin secretion if pO 2 < 0.1 mmHg) was 0.3% for human islets (OCR ~100 nmol/min/mg DNA) and 35% for porcine islets (OCR ~300 nmol/min/mg DNA). The OCR of the islet preparation is profoundly affected by islet size, with optimal size of <250 μm in diameter (human) or <150 μm (porcine). Our data suggest that microcapsules afford superior oxygen delivery to encapsulated islets than macrocapsules, and optimal islet function can be achieved by encapsulating multiple, small (<150 μm) islets with OCR of ~100 nmol min −1 mg −1 DNA (human islets) or ~200 nmol min −1 mg −1 DNA (porcine islets).