Establishment of a Murine Model of Allogeneic Umbilical Cord Blood Transplantation

This study was undertaken to establish a murine model of unrelated allogeneic umbilical cord blood transplantation (UCBT). To investigate the potential possibility to reconstitute the immunohematopietic system in adult mice recipients across major histocompatibility complex by mixed 2 near term cord blood transplantation: 1×10⁶ umbilical cord blood mononuclear cells from 20 day old C57BL/6 (H2^b) pups and 1×10⁶ umbilical cord blood mononuclear cells from 20 day old C3H (H2^k) mixed pups delivered by cesarean were injected into lethally irradiated (8.0Gy) BALB/c (H2^d) adult mice in the same time. After one month, anti-H2^b and anti-H2^k antibody were used to investigate donor chimera in recipients. Results showed that all of the control mice that reconstituted with only 1×10⁶ umbilical cord blood mononuclear cells from 20-day-old C57BL/6 (H2^b) pups died with in three weeks after radiation. 70% recipients that reconstituted with mixed umbilical cord blood mononuclear cells survived in the observation period of three months. Two donors mixed chimera was demonstrated by using anti-H2^b and anti-H2^k antibody in the same recipient. In vitro mixed lymphocyte response showed immune tolerance. The results confirmed that two kinds of umbilical cord blood can form mixed chimera in the same adult mice recipients. Mixed umbilical cord blood transplantation can reconstitute the immunohematopietic system in adult mice recipients without causing serious GVHD. This model may be suitable to address many questions raised in clinical mixed umbilical cord blood transplantation.