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Regulation of Proliferation and Chondrogenic Differentiation of Human Mesenchymal Stem Cells by Laminin‐5 (Laminin‐332)

Laminin‐5 (laminin‐332) is an important basement membrane protein that regulates cell attachment and motility. Recent studies have shown that laminin‐5 is expressed in human mesenchymal stem cells (MSCs) in culture and that the laminin γ2 chain is transiently expressed in chondrocytes during development. These studies suggest that laminin‐5 may be involved in the regulation of chondrogenic differentiation of MSCs. In this study, we examined a possible role of laminin‐5 in the proliferation and differentiation of human MSCs. When MSCs were incubated in the presence of a coated or soluble form of laminin‐5 in a growth medium, they proliferated more rapidly than nontreated cells, keeping their differentiation potential. On the other hand, laminin‐5 potently suppressed the chondrogenic differentiation of MSCs. These activities were mediated mainly by integrin α3β1. However, laminin‐5 had no effect on the osteogenic differentiation of MSCs. These results suggest that laminin‐5 may contribute to the development of bone tissues by promoting the proliferation and by suppressing the chondrogenic differentiation of MSCs.