Developing animal embryos have been providing human mesenchymal stern cells (hMSCs) with an appropriate environment for their differentiation between species. We previously demonstrated that hMSCs transplanted into the metanephric mesenchyme region of rat embryos differentiate into kidney-specific cells. Here, we assessed whether hMSCs are competent to differentiate into precursors of the collecting duct system when they are transplanted into the ureteric bud progenitor region of chicken embryos that are easier to be manipulated and cultured than mammalian embryos. When chicken Pax2-expressing hMSCs were transplanted into the chicken ureteric bud progenitor region, they migrated caudally with the elongating Wolffian duct and then were integrated into the Wolffian duct epithelia. Also, chicken Pax2-expressing hMSCs started to express human LIM1 after their integration into the Wolffian duct epithelia. These results suggest that chicken Pax2-expressing hMSCs can be competent to differentiate into the Wolffian duct cells by the influence of chicken local signals. (C) 2009 Elsevier Inc. All rights reserved.