THE EFFECT OF HUMAN CORD-BLOOD ON SJL/J MICE AFTER CHEMOABLATION AND IRRADIATION AND ITS POSSIBLE CLINICAL-SIGNIFICANCE

There is evidence from the existing published literature that human umbilical cord blood, when used for purposes of bone marrow transplantation, does not necessarily have to be HLA matched in order to be efficacious. These reports include experimental observations on the ability of human umbilical cord blood to rescue lethally irradiated mice and clinical observations from China wherein HLA mismatched umbilical cord blood has been engrafted successfully in children with malignant disease. The study reported herein describes an experimental immunocompetent murine model to determine if human umbilical cord blood can be used to improve survival after chemoablation and irradiation. The animals received chemoablation followed by irradiation, and irradiation alone. The presence of human DNA in these mice following injection of human umbilical cord blood cells was determined, and the immunological status of the animals was evaluated. Animals receiving human umbilical cord blood cells after chemoablation and irradiation had a better mean survival at day 50 than animals receiving syngeneic marrow. Human DNR could be found in various organs, particularly the lung, spleen and liver of the mice for the first 30 days. Thereafter, human DNA became more difficult to detect but trace amounts of human DNA could be found up to one year later. The results of mixed lymphocyte reactions and phenotype analyses for murine T cell markers performed after injection of HUCB cells both indicated endogenous repopulation, and relatively intact immune systems in these mice. Since human umbilical cord blood allowed mice to survive the lethal effects of chemoablation plus irradiation, or irradiation alone, with reconstitution of the animals' own, relatively intact, immune systems, it would appear that HLA mismatched human umbilical cord blood could potentially be used as an adjuvant treatment for patients with advanced malignancies or other diseases for which hematopoietic reconstitution is indicated.