Hematopoietic activity of common marmoset CD34 cells isolated by a novel monoclonal antibody MA24

Objective We focused on a small New World monkey, the common marmoset (Callithrix jacchus), to establish a nonhuman primate model of the treatment of hematological disorders. In this study, we developed the first monoclonal antibodies (MAbs) against marmoset CD34 and tested the in vitro and in vivo hemopoietic activity of cell populations isolated using one of these MAbs. Methods and Results Marmoset cDNA encoding a human CD34 homologue was cloned from bone marrow (BM)–derived RNA using reverse transcription polymerase chain reaction and rapid amplification of cDNA ends. The amino acid sequence of the marmoset CD34 had 81% homology with the human sequence. Five mouse MAbs were raised against marmoset CD34 transfectant. One representative MAb, MA24 (IgM), reacted with approximately 0.5 to 1% of BM mononuclear cells (MNCs), where the colony-forming unit granulocyte/macrophage (CFU-GM) was enriched approximately 11- to 75-fold as compared with the whole BM MNCs. Multilineage differentiation of marmoset CD34+ cells in NOD/SCID mice was confirmed by flow cytometry 1 month after xenotransplantation. Conclusion These results demonstrated that MA24 is useful for the analysis and enrichment of hematopoietic progenitor cells in the marmoset model for preclinical experiments.