The combination method using magnetic beads and a magnet helps sustain the number of donor BM cells after intra-BM injection, resulting in rapid hematopoietic recovery.

We have developed a new BMT method, intra-BM-BMT (IBM-BMT), in which donor BM cells (BMCs) are directly injected into the recipient’s BM, resulting in a rapid recovery of donor hematopoiesis and a reduction in the severity of GVHD. In the present experiment, we attempted to retain the number of injected BMCs using magnetic beads and a magnet. The BMCs of donor mice were conjugated with magnetic beads, and these cells were then injected into the BM of recipient mice with a magnet (magnet-IBM group) and compared with conventional IBM-BMT without a magnet (IBM group). A significantly higher number of transplanted cells were detected in the injected BM in the magnet-IBM group. We next carried out day-12 colony-forming units of spleen (CFU-S) assays to examine the early stage of hematopoiesis of the injected host hematopoietic stem cells after IBM-BMT. The spleens of mice in the magnet-IBM group showed considerably higher CFU-S counts than those in the IBM group. Excellent reconstitution of donor hematopoietic cells in the magnet-IBM group was observed 1 month after IBM-BMT. These results suggest that the IBM-BMT using the combination of magnetic beads and a magnet is superior to the conventional IBM-BMT. [ABSTRACT FROM AUTHOR]