431 MULTIPOTENT ADULT PROGENITOR CELLS CAN RECONSTITUTE LYMPHOHEMATOPOIETIC LINEAGES AND CONTRIBUTE TO NONHEMATOPOIETIC SYSTEMS IN IRRADIATED IMMUNODEFICIENT MICE. (1st January 2006) - Fine, G. C.
Abstract : Multipotent adult progenitor cells (MAPCs) are rare cells that have been identified within human and rodent bone marrow (BM) that can differentiate into mesodermal, endodermal, and ectodermal lineages in vitro. High O2 (20%) MAPCs also differentiate into hematopoietic stem cells (HSC) in vivo in NOD/SCID mice with very low engraftment levels. Since the initial description of MAPCs, we modified our culture conditions to isolate MAPCs under 5% O2 conditions, resulting in MAPCs with higher mRNA and protein levels of the ES-transcription factor, Oct4, and greater in vitro differentiation potential. We investigated the hematopoietic and nonhematopoietic engraftment levels of eGFP/CD45.2 transgenic C57Bl/6 MAPCs in NOD/SCID (CD45.1 positive) mice irradiated with 275cGy and treated with anti-asialo GM1 antibody (Ab) on days 1, 11, and 22 following transplantation. When 10 6 MAPCs were transplanted, up to 70% GFP/CD45.2 cells were present in peripheral blood (PB), BM, and spleen at 13 weeks post-transfer. Lymph nodes and Peyer's patches also contained GFP+ cells. FACS analysis of cells from spleen, BM, and PB revealed multilineage engraftment with differentiation to myeloid, B, and T-lymphoid cells. We detected eGFP+ cells co-expressing Sca1+/cKit+ or Thy1+/cKit+, suggesting generation of HSCs from MAPCs, consistent with the finding that GFP+ CFU-Mix, BFU-E, and CFU-GM were present. eGFP+ splenic T cells were capable of reacting to Balb/C-derived cells and to stimulation by anti-CD3+anti-CD28 monoclonal Abs. We measured the percentage of GFP using real-time PCR and detected its presence in lung, liver, intestine, kidney, stomach, and spleen as early as 3 weeks following transplantation, pancreas as early as 6 weeks, and skin as early as 12 weeks. In conclusion, MAPCs isolated in 5% O2 conditions and grafted in the presence of anti-NK Abs engraft in lymphohematopoietic and some nonhematopoietic organs to a significantly greater extent than was previously demonstrated. Thus, MAPCs may be an alternative source of HSCs to treat congenital or acquired hematopoietic disorders or to establish chimerism prior to using the same cells to treat disorders amenable to MAPC-derived therapies.