Heparins modulate extracellular matrix and protein synthesis of cultured rat mesangial cells

Heparins blunt the development of glomerulosclerosis in several disease models in the rat and this protective effect may be related to suppression of glomerular cell proliferation. In this study the direct effect of heparins on another key event in glomerulosclerosis, extracellular matrix (ECM) deposition, was examined. Standard heparin (hep) and non-anticoagulant N-desulfated acetylated heparin (DSA-hep) significantly reduced the fibronectin content in the conditioned media of subconfluent, confluent, and supraconfluent rat glomerular mesangial cells (MCs) in culture, as assessed by a sandwich ELISA technique. Both heparins significantly increased the amount of cell-associated fibronectin in sparse and subconfluent MCs. DSA-hep, but not hep, increased the fibronectin content of ECM formed by confluent and supraconfluent MCs. Using H-3-proline pulse-labeling, Hep and DSA-hep were found to significantly decrease cell-associated collagen in subconfluent but not in confluent MCs. No effects were seen on newly synthesized collagen secreted into the culture medium. Neither hep nor DSA-hep affected total protein synthesis, studied by metabolic labeling with S-35-methionine. High resolution 2-D electrophoresis (molecular weight range, 120 to 10 Kd; isoelectric interval, 5.0 to 7.0) revealed one particular intracellular protein (molecular weight 54 Kd, pI 5.91) which was consistently overexpressed by MCs exposed to DSA-hep but underexpressed in hep. Both heparins affected an identical set of another 19 different intracellular MC proteins (over-/underexpression or shift to higher molecular weights). In conclusion, the present data demonstrate the profound direct metabolic effects of hep and DSA-hep. In addition to their antiproliferative activity, heparins may also affect the course of glomerular disease in-vivo by direct modulation of ECM and protein synthesis of MCs.