DETECTION OF HUMAN MYELOID PROGENITOR CELLS IN A MURINE BACKGROUND

Cell-mixing experiments were performed to determine whether human (hu) peripheral blood plasma would select for the growth of hu myeloid pro genitor cells in vitro. Mixtures of hu male umbilical cord blood and m urine (mu) female bone marrow (100% hu, 100% mu, 1.0% hu or 10% hu and 50% hu) were plated in.methylcellulose cultures that contained either hu plasma or fetal bovine serum (FBS). Cultures were supplemented wit h recombinant (r) hu erythropoietin (Epo) alone or in combination with rhu granulocyte-macrophage colony stimulating factor (GM-CSF), rmuGM- CSF or rhu steel factor (SLF). DNA was extracted from day 14 colonies and clusters, and the polymerase chain reaction (PCR) was used to dete ct the hu Y-chromosome satellite DNA sequence. Results of these studie s revealed that hu plasma used in combination with hu growth factors s elected for the growth of hu progenitor cells. Mu cells grew in hu pla sma only at high cell-plating concentrations. This selective effect wa s due to a heat labile factor or factors, since mu cells grew equally well in heat-inactivated hu plasma and FBS. Cells in individual progen itor cell colonies and clusters cultured in hu plasma contained hu Y-c hromosome-specific DNA sequences that were detectable after PCR-mediat ed amplification, thus eliminating the need for time-consuming Souther n transfer. This study describes a method whereby hu/immune-deficient mice can be screened rapidly for hu myeloid engraftment. These results also indicate that the hu identity of colonies and clusters cultured in hu plasma must be genetically confirmed, especially when hu cells m ay represent a low percentage of the total cells plated.