The immunoregulatory properties of hematopoietic stem cells (HSCs) have been recognized for more than 60 years, beginning in 1945, when Owen reported that genetically disparate freemartin cattle sharing a common placenta were red blood cell chimeras. In 1953, Billingham, Brent, and Medawar demonstrated that murine neonatal chimeras prepared by infusion of donor-derived hematopoietic cells exhibited donor-specific tolerance to skin allografts. Various approaches using HSCs in organ transplantation have gradually brought closer to reality the dream of inducing donor-specific tolerance in organ transplant recipients. Several hurdles needed to be overcome, especially the risk of graft-versus-host disease (GVHD), the toxicity of ablative conditioning, and the need for close donor-recipient matching. For wide acceptance, HSC therapy must be safe and reproducible in mismatched donor-recipient combinations. Discoveries in other disciplines have often unexpectedly and synergistically contributed to progress in this area. This review presents a historic perspective of the quest for tolerance in organ transplantation, highlighting current clinical approaches.
ASJC Scopus subject areas
- Pharmacology (medical)