Differences among nonhuman primates in susceptibility to bone marrow progenitor transduction with retrovirus vectors

Nonhuman primates are increasingly being used as models for pre-clinical assessment of retrovirus vector expression and function following stem and progenitor cell transduction. We compared the relative susceptibility of CD34+ marrow progenitors from four nonhuman primate species and humans to transduction with amphotropic pseudotyped retrovirus vectors containing the Neo gene. The rate of functional gene transfer was measured by colony formation under G418 selection. Marrow progenitors from pigtail macaques (Macaca nemestrina) were transduced at about twice the rate (19.1 +/- 4.3%) as those from rhesus (11.2 +/- 3.7%) and cynomolgus (7.6 +/- 1.9%) macaques, baboons (7.8 +/- 1.8%), and humans (9.6 +/- 1.7%). Semiquantitative RT/PCR analysis suggests this difference may be due to elevated expression of the amphotropic receptor Pit2 in pigtailed macaque CD34+ cells. Further, transduction rates increased an average 1.6 +/- 0.4-fold when the culture temperature was lowered to 33 degrees C, and 2.1 +/- 0.3-fold when the culture dishes were coated with the fibronectin fragment CH-296. The data presented here point to important differences among nonhuman primate models as well as transduction culture conditions, and suggest that pigtailed macaques may be particularly useful for assessing expression and function of therapeutic retrovirus vectors. Gene Therapy (2000) 7, 359-367.