Characterization of adult human heart fibroblasts in culture: a comparative study of growth, proliferation and collagen production in human and rabbit cardiac fibroblasts and their response to transforming growth factor-beta1.

Abstract

Fibroblasts constitute the majority of non-myocyte cells in the heart, but little is known about the biology of human cardiac fibroblasts. We have cultured and characterized fibroblasts from young adult human heart and compared their biological features with those of cells obtained from the ventricular tissue of sex- and developmental-stage-matched rabbits. Cell morphology and growth was determined by light microscopy and by measuring protein synthesis. The proliferative capacity of cells was determined by measuring the doubling time and the level of incorporation of 3H-thymidine into DNA under normal conditions of cell culture and in response to several growth factors. Production of collagen type I was determined at the mRNA level by assessing the steady state level of pro alpha1 20(l) collagen mRNA in cardiac fibroblasts under normal culture conditions and in response to transforming growth factor-beta (TGF-beta), and at the protein level by immuno-slot blot analysis. Ventricular tissue from adult human heart was used successfully for the preparation of passagable (up to nine passages) cultured cardiac fibroblasts. They had a significantly larger surface area per cell than rabbit cells. Under normal culture conditions, they showed a lower rate of DNA synthesis and longer doubling time than rabbit cardiac fibroblasts at the matching passage. The magnitude of growth-factor-induced changes in the incorporation of 3H-thymidine into DNA was lower in human cells than in rabbit cardiac fibroblasts, as was the level of mRNA for pro alpha1(l) collagen. The TGF-beta1-induced increase in pro alpha1(l) collagen mRNA was modest in human cardiac fibroblasts. Thus, significant differences exist between the biological properties of human and rabbit cardiac fibroblasts in culture.