The proliferation and differentiation of placental-derived multipotent cells into smooth muscle cells on fibrillar collagen

Type I collagen constitutes a major portion of the extracellular matrix (ECM) in arterial wall and it is the major substrate for cell growth and differentiation. The goal of this study was to evaluate the differentiation and proliferation of placenta-derived multipotent cells (PDMCs) on polymerized type I collagen fibrils and monomer collagen. PDMCs grown on both polymerized collagen and monomer collagen with transforming growth factor (TGF)-β treatment increases the expression of smooth muscle cell (SMC)-specific markers, including calponin, α-smooth muscle actin (α-SMA) and smooth muscle-myosin heavy chain (SM-MHC). Polymerized collagen increased the expressions of p21CIP1 and p27KIP1; decreased cyclin A, cyclin D1, cyclin-dependent protein kinase 2 (Cdk2); and led to G0/G1 arrest in PDMCs. Furthermore, PDMC–differentiated SMCs exhibited significant collagen contractility in the presence or absence of endothelin-1 (ET-1) stimulation. By using specific inhibitors and small interfering RNA (siRNA), we demonstrated that p38 MAPK pathway and serum response factor (SRF)–DNA binding activity is critical for the polymerized collagen-induced PDMC differentiation into SMCs. Thus, polymerized collagen exhibits the great potential in inducing PDMCs differentiation into SMCs, and exerts anti-proliferative effect on PDMC–differentiated SMCs.