The present invention provides methods, improved cell culture medium and kits for promoting hematopoietic and mesenchymal stem and lineage-specific cell proliferation and differentiation by growth in the presence of angiotensinogen, angiotensin I (Al), AI analogues, AI fragments and analogues thereof, angiotensin II (AII), AII analogues, AII fragments or analogues thereof or AII AT.sub.2 type 2 receptor agonists, either alone or in combination with other growth factors and cytokines.