Placental blood-derived hematopoietic stem cells for unrelated bone marrow reconstitution.

"Transplants" of placental blood from siblings have been successful in the reconstitution of ablated bone marrow. We are currently evaluating the feasibility of applying this source of hematopoietic stem cells in the case of unrelated recipients. Availability, ease and low cost of recovery, absence of risk to the donors, unbiased ethnic participation, and possibly advantageous immunological and infectious disease characteristics are evident advantages in comparison to registries of volunteer marrow donors. In this report we review selected aspects of the comparison and discuss selected areas of special interest to the practical application of this source of stem cells. We also present new data that reinforce earlier suggestions of a reduced capacity of allorecognition of placental blood lymphocytes, using as controls the lymphocytes of their respective HLA-identical siblings.