The present invention provides compositions and methods of using placental stem cells that originate from a post-partum placenta with conventional cord blood compositions or other stem or progenitor cells. The placental stem cells can be used alone or in a mixture with other stem cell populations. In accordance with the present invention, the placental stem cells may be mixed with other stem cell populations, including but not limited to, umbilical cord blood, fetal and neonatal hematopoietic stem cells and progenitor cells, human stem cells and progenitor cells derived from bone marrow. The placental stem cells and the mixed populations of placental stem cells and stem cells have a multitude of uses and applications, including but not limited to, therapeutic uses for transplantation and treatment and prevention of disease, and diagnostic and research uses.
