Background: Human amnion epithelial cells (hAECs) have demonstrated great promise for regenerative medicine, possessing multipotent differentiation ability, low immunogenicity and anti-inflammatory properties. Using the bleomycin lung injury mouse model, we have shown for the first time that hAECs can prevent and reduce lung injury. However, the exact regenerative and reparative mechanisms of hAECs have yet to be evaluated. In this study, we investigated the potential of hAECs to affect endogenous bronchioalveolvar stem cells (BASCs) following bleomcycin-induced lung injury.
Method: Immunocompetent mice (C57Bl6) were given a single intranasal dose of bleomycin. After 24 hours, saline (vehicle) or 4x106 hAECS were administered via an intraperitoneal injection. These groups were named: B+S and B+hAEC. Mice were sacrificed at Day 3 or Day 7; lungs were collected and digested into a single cell suspension. BASCs were identified as CD45neg CD31neg Sca-1pos CD34pos and collected for an in vitro colony-forming assay.
Results: Compared to saline treated animals, administration of hAECs resulted in a slight increase in BASC numbers at Day 3. This increase was significant by Day 7. BASCs isolated from B+S and B+hAEC animals on Day 3, gave rise to colonies and formed three-dimensional structures similar to embryoid bodies. BASCs isolated from B+hAEC animals on Day 7 gave rise to colonies but failed to form three-dimensional ‘embryoid bodies’.
Conclusions: Treatment with hAECs following bleomycin challenge appeared to trigger the expansion of endogenous BASCs as early as Day 3. BASCs isolated from B+hAEC animals on Day 7 appear to display reduced stem cell properties. These preliminary findings, in combination with our published work, suggests that that administration of hAECs may recruit endogenous lung stem cells to aid in lung repair as well as promotes their differentiation.