HGF and pulmonary emphysema: These findings, using human cells, support previous work using a murine elastase model of emphysema, which revealed that intratracheal administration of LR-MSCs resulted in enhanced HGF expression and the promotion of ATII cell numbers as an MSC-dependent paracrine mechanism for the repair of injured alveoli.89 HGF is a mesenchymal-derived paracrine factor that has pleiotropic effects and can promote epithelial proliferation, morphogenesis, migration, and anti-apoptotic responses, thus making it an important mechanism of repair for LR-MSCs.