Skin biopsies were obtained from diabetic and nondiabetic Pima Indians and nondiabetic Caucasian controls to compare fibroblast growth characteristics. The Pima population were used because they have a high prevalence of well-characterized diabetes mellitus, and extensive clinical and demographic data are available for selection of subjects.Cultures were derived from 19 subjects between the ages of 20 and 42 yr. Seven were from Pimas with severe diabetes who had two diabetic parents and relatively early age of onset. Six were from Pima nondiabetics who had two nondiabetic parents. Six control cultures were established from Caucasian nondiabetics with no family history of diabetes. Cell density at confluence, plating efficiency, thymidine incorporation, and population doubling rates were monitored as a function of cell population doublings until the senescence of each culture. Fibroblast cultures from the Pima diabetics did not differ from those of the Pima nondiabetics in replicative life span or any of the measured culture parameters. When cultures from the Pimas were compared with those of the Caucasian controls, however, they had decreased cell density at confluence, slower population doubling times, decreased thymidine incorporation, shorter replicative life spans, and lower plating efficiency. The data suggest that altered growth properties of cultures from diabetics may not be a requisite of diabetic status; they may reflect a genetic background that accompanies the expression of diabetes.

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