PEDIATRIC CARDIAC XENOGRAFT GROWTH IN A RHESUS MONKEY-TO-BABOON TRANSPLANTATION MODEL

It is unclear that organs from other species could grow successfully i n the environment of another species. We evaluated the growth capacity of a cardiac xenograft in a rhesus monkey-to-juvenile baboon orthotop ic heart transplantation model where there exists a discrepancy of the organ size and its growth rate between donor and recipient species. E ight recipient baboons who survived over 60 days were followed for bod y weight (BW) and the size of xenografts (left ventricular end-diastol ic volume, LVEDV; left ventricular mass, LVM; and left ventricular pos terior wall thickness, LVPWT) by echocardiography at 1 week and monthl y after xenotransplantation. One baboon is growing along the normal gr owth curve. The other three baboons gained BW in parallel with normal growth curve except for a few months after surgery. LVEDV, LVM, and LV PWT increased constantly in these four baboons. In one baboon, BW incr eased over 1 year to 5.5 kg (which was almost the same as BW of adult rhesus monkey) and then plateaued. LVEDV, LVM, and LVPWT increased unt il 1 year posttransplantation, but then stopped when BW plateaued. In the other four baboons who did not gain BW because of infectious compl ications or side effects by immunosuppressive therapy, LVEDV, LVM, and LVPWT did not change significantly. We conclude that a cardiac xenogr aft from a rhesus monkey can successfully grow and support normal grow th of a juvenile baboon. but whether a recipient can grow beyond the d onor size is yet unknown.