Insulin Effects on Collagen and Protein Production in Cultured Human Skin Fibroblasts from Diabetic and Non-Diabetic Subjects

Summary

The influence of insulin on collagen and total protein production was studied in cultured human skin fibroblasts from patients with Type 1 (insulin-dependent) diabetes and Type 2 (non-insulin-dependent) diabetes, and from non-diabetic subjects. Fibroblast cultures were exposed to various concentrations of insulin (0-10⁵ mU/l) for 48 hours in serum-free medium containing tritium labelled proline.

With medium glucose at 5.6 mmol/l, cells from diabetic subjects displayed an increase in collagen and protein radioactivities in the extracellular medium in the presence of insulin at 10² or 10³ mU/l. Concentrations above 10³ mU/l did not stimulate further. In cells from non-diabetic subjects, stimulated incorporation was evident only at insulin 10³ mU/l.

In the presence of high glucose concentration (38.9 mmol/l) in the medium, the lowest insulin level (10² mU/l) did not influence collagen production in any cell type, and the effects of insulin on total protein radioactivity was reduced in all cells.

The enhancement by insulin of collagen secretion, and the higher sensitivity of cells from diabetics to this insulin action, is of interest in relation to the possible role of insulin in the accelerated atherosclerosis observed in diabetics.

Key-Words:

Diabetes Mellitus - Human Skin Fibroblasts - Insulin - Collagen - Protein - Proline Incorporation