Angiogenic and growth factors in human amnio-chorion and placenta

Human amnio-chorionic membranes and placenta maintained in culture release factors with angiogenic and mitogenic capacities at concentrations corresponding to nanogram amounts of protein. Angiogenic activity of amnio-chorion and placenta-conditioned media was assessed by their ability to stimulate neovascularisation in the dorsal subcutaneous fascia in the rat and the chorio-allantoic membrane in the chick embryo. Mitogenic characteristics were assessed by their ability to initiate DNA synthesis in cells at resting state, unstimulated peripheral blood lymphocytes and serum-deprived 3T3 fibroblasts. These growth promoting factors can be isolated from amnio-chorion and placenta-conditioned media mostly as factor-protein complexes of high molecular weight (higher than 100000 daltons) by gel filtration, and dissociated by magnesium chloride in components of low molecular weight including molecules readily diffusable through dialysis membranes of 2000 molecular weight cutoff. Presence of angiogenic and mitogenic factors in amnio-chorion suggests they might play a role in wound healing when amniotic membranes are used as biological dressings, besides the role they may play, in conjunction with placental factors, in embryonic and foetal development.