Human placental laminin: Role in neuronal differentiation, cell adhesion and proliferation

Human placental extract has wound healing potential. Immuno-blots revealed presence of laminin in placental extract (70 +/- 0.257 mu g/ml; n=3). It was purified using immuno-affinity chromatography. SDS-PAGE and SE-HPLC indicated a188 kDa protein with some small peptides. Since placental laminin existed in its truncated form, its roles in cellular migration, differentiation and wound healing were verified. Induction of cellular migration and motility in rat fibroblasts were enhanced by placental laminin as observed from scratch wound assay. Promotion of neuronal differentiation of PC12 cells by placental laminin was observed by phase contrast microscopy. Confocal images showed presence of laminin on the cell surface and along the axonal processes. Significant interaction between integrin receptors and laminin responsible for cellular differentiation was demonstrated from co-localization experiments. Union between integrin receptor and its synthetic antagonist revealed retarded pattern of neurite outgrowth in laminin treated cells. Animal model studies revealed faster wound healing in the presence of placental laminin. Induction of re-epithelialization and angiogenesis in wound area by cellular proliferation and adhesion were observed. The cytokine levels showed an initial rise and gradual fall over the duration of wound healing on application of the fragmented laminin. Thus, roles of placental laminin in neuronal differentiation and wound healing were indicated.