Sera from type 2 (non-insulin-dependent) diabetic and healthy subjects contain different amounts of a very low molecular weight growth peptide for vascular cells.

Diabetic angiopathy may be due, in part, to increased growth in vascular cells. We have investigated serum growth factors in Type 2 (non-insulin-dependent) diabetic and healthy subjects and their effect on cultured human arterial smooth muscle cells and fibroblasts. Removal of the dialyzable serum fraction (mol. wt. less than 12,000) reduced the growth effect of the diabetic sera by 37% (2p less than 0.005) and of the non-diabetic sera by only 8% (2p less than 0.01). In contrast, there was no difference in growth stimulation between the dialyzed diabetic or non-diabetic sera. Complete recovery of the dialyzable serum growth fraction was also obtained at a mol. wt. below 3,500. Ten times the concentration of the low molecular weight growth factor (mol. wt. less than 3,500) from diabetic sera stimulated growth of fibroblasts or arterial smooth muscle cells by a mean of 243% or 174% and from non-diabetic sera by a mean of 146% or 137%, respectively (2p less than 0.01). The growth stimulating potency of this serum fraction (mol. wt. less than 3,500) contained in 10% diabetic sera, was two to ten times higher than that of human growth hormone or insulin, added in amounts equivalent to 10% or physiological serum concentrations. This diabetic serum growth factor was further characterized by: (1) linear dependence of growth stimulation over a concentration range of twenty times and by (2) reduction of the growth stimulating activity to control levels by pretreatment: (a) at 95 degrees C for 30 min, or (b) with two different proteases: Serva pronase E (Streptomyceus griseus) or Calbiochem protease (Subtilisin calsberg).(ABSTRACT TRUNCATED AT 250 WORDS)