Osteogenic responses in fibroblasts activated by elastin degradation products and transforming growth factor-beta1: role of myofibroblasts in vascular calcification.

Department of Bioengineering, 501 Rhodes Center, Clemson University, Clemson, SC 29634, USA.

Our objective was to establish the role of fibroblasts in medial vascular calcification, a pathological process known to be associated with elastin degradation and remodeling. Rat dermal fibroblasts were treated in vitro with elastin degradation products and transforming growth factor (TGF)-beta1, factors usually present in deteriorated matrix environments. Cellular changes were monitored at the gene and protein level by reverse transcriptase-polymerase chain reaction, enzyme-linked immunosorbent assay, immunofluorescence, and von Kossa staining for calcium deposits. By 21 days, multicellular calcified nodules were formed in the presence of elastin degradation products and TGF-beta1 separately and to a significantly greater extent when used together. Before mineralization, cells expressed alpha-smooth muscle actin and large amounts of collagen type I and matrix metalloproteinase-2, characteristic features of myofibroblasts, key elements in tissue remodeling and repair. Stimulated cells expressed increased levels of core-binding factor alpha1, osteocalcin, alkaline phosphatase, and osteoprotegerin, representative bone-regulating proteins. For most proteins analyzed, TGF-beta1 synergistically amplified responses of fibroblasts to elastin degradation products. In conclusion, elastin degradation products and TGF-beta1 promote myofibroblastic and osteogenic differentiation in fibroblasts. These results support the idea that elastin-related calcification involves dynamic remodeling events and suggest the possibility of a defective tissue repair process.

PMID: 17591959 [PubMed - indexed for MEDLINE]

PMCID: PMC1941602