Glucose stimulation of cytochrome C reduction and oxygen consumption as assessment of human islet quality.
BACKGROUND
An in vitro method to assess human islets could prevent transplantation of nonviable islets and facilitate the optimization of islet preparation. We hypothesize that glucose-stimulated cytochrome c reduction and oxygen consumption by human islets can be used as predictors of transplant success.


METHODS
Isolated human islets were obtained from research-grade pancreata. Using a previously developed islet flow culture system, the response of cytochrome c reduction and oxygen consumption to glucose was compared to the ability of islets transplanted into nondiabetic NOD-SCID mice to secrete C-peptide in response to a glucose tolerance test conducted 7 days following transplant (n=10).


RESULTS
In vitro responses by human islets were qualitatively similar to those seen in rat islets: glucose increased both oxygen consumption and cytochrome c reduction. However, the responses were smaller in magnitude and quite variable. Scatter plots of C-peptide and quantiles for ln(C-peptide) indicated that 12 ng/ml could be used as threshold of transplant success with which to evaluate the diagnostic potential of cytochrome c and oxygen consumption. Data was analyzed by generating receiver operating curves and the area under the curve was 0.889 (95% CI: 0.645-1.000) and 0.738 (95% CI: 0.413-1.000) for cytochrome c reduction and oxygen consumption respectively (1 indicates absolute predictive capability and 0.5 indicates no predictive capability).


CONCLUSIONS
The detection of glucose-stimulated cytochrome c reduction and oxygen consumption may have utility as criteria for the assessment of human islet quality.
Sweet
Ian R
IR
Department of Medicine, University of Washington, Seattle, WA 98195-7710, USA. isweet@u.washington.edu
Gilbert
Merle
M
Jensen
Rich
R
Sabek
Omaima
O
Fraga
Daniel W
DW
Gaber
Ahmed O
AO
Reems
JoAnna
J
D000818:Animals; D002478:Cells, Cultured; D045304:Cytochromes c / Q000032:analysis / Q000378:metabolism*; D005947:Glucose / Q000494:pharmacology*; D006801:Humans; D007328:Insulin / Q000378:metabolism; D000078790:Insulin Secretion; D007515:Islets of Langerhans / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism; D016381:Islets of Langerhans Transplantation; D008297:Male; D051379:Mice; D016513:Mice, SCID; D010084:Oxidation-Reduction; D010101:Oxygen Consumption / Q000187:drug effects*; D051381:Rats; D011916:Rats, Inbred F344
D007328:Insulin; D045304:Cytochromes c; D005947:Glucose