OBJECTIVETo explore the effect of all-trans retinoic acid (RA) on the engraftment of unrelated umbilical cord blood stem/progenitor cell transplantation (UCBT) in murine model.

METHODS1 x 10(6) and 0.5 x 10(6) nucleated cells (NC) from C57BL/6 (H-2(b)) fetal and neonatal peripheral blood (FNPB) were separately transfused into lethally cyclophosphamide (380 mg/kg, ip) treated BALB/C (H-2(d)) recipients, 15 mg.kg(-1).d(-1) and 5 mg.kg(-1).d(-1) RA (15 mg and 5 mg RA) were administrated respectively 2 days before and after UCBT. Hematopoiesis and immune recovery, graft versus host disease (GVHD), engraftment and survival rates were then observed.

RESULTSHematopoiesis and immune recovery occurred faster in RA treated than in untreated mice (P < 0.05). Acute GVHD was absent. The levels of engraftment were higher in both 15 mg and 5 mg RA treated mice than those in untreated controls (P < 0.05). In 1 x 10(6) NC transfused mice, 15 mg and 5 mg RA could significantly increased the 30 and 60 days survival rates from 41.67% (without RA) to 72.23% and 70.83%, respectively (P < 0.05). In 0.5 x 10(6) cells transfused mice, 15 mg and 5 mg RA increased the survival rate from 14.29% (without RA) to 42.86% and 43.48%, respectively (P < 0.05), which were comparable to that of being transfused 1 x 10(6) cells without RA treatment (P > 0.05).

CONCLUSIONRA enhances the engraftment of umbilical cord blood stem/progenitor cells in murine model for UCBT. This might provide an experimental evidence of RA in clinical UCBT.