Determination of engraftment potential of human cord blood stem-progenitor cells as a function of donor cell dosage and gestational age in the NOD/SCID mouse model

Objective: The purpose of this study was to determine cell dosage parameters for successful engraftment of human cord blood hematopoietic stem cells (HSC) using an in vivo assay system, and to determine if there are differences with donor gestational age. Study design: HSCs were transplanted into nonobese diabetic-severe combined immunodeficient (NOD/SCID) mice. Donor cell dosage and gestational age ranges were 1 to 40×10⁶ CD34+ cells per mouse, and 23 to 40 weeks, respectively. Recipient bone marrow was assessed for engraftment capacity of the HSCs. Results: There was increasing engraftment levels with increasing dosages of transplanted HSCs. When controlled for donor HSC dosage, engraftment levels using donor cord blood from earlier gestational ages were not different from that seen using later gestational ages. Conclusion: Similar dose responses are seen using HSCs derived from the late second trimester until term in engraftment potential in the NOD/SCID mouse model. Results from this study may be applicable to human postnatal and in utero transplantation studies.