Method — Intra-bone marrow transplantation of hematopoietic stem cells in non-human primates: long-term engraftment without conditioning

It has recently been reported that bone marrow cells can efficiently engraft without marrow conditioning when implanted directly into the bone marrow cavity (intra-bone marrow transplantation, iBMT) in mice. We have successfully examined the efficacy of autologous iBMT in a cynomolgus monkey model in conjuction with an in vivo expansion of transplanted cells by a selective amplifier transgene (Ueda et al., 2004) and provide here the detailed parameters of our iBMT method. We injected retrovirally-marked autologous CD34+ cells directly into the non-conditioned marrow cavity of the femur and humerus after gently irrigating the cavity with saline. This transplant procedure was safely performed without pulmonary embolism. Gene-marked cells were not detectable in the peripheral blood at one hour and one day after iBMT as assessed by sensitive PCR, indicating that iBMT hardly generated a systemic delivery of transplanted cells. On the other hand, 2 to 30% of clonogenic hematopoietic colonies produced from the implanted marrow were gene-marked at 6–12 months after iBMT. Our iBMT method for non-human primates is thus discussed in terms of long-lived hematopoietic stem/progenitor cells, bone marrow niche and long-term engraftment after iBMT without myeloablative conditioning.