Growth of xenografted human bone marrow: comparison with hemopoietic reconstitution in patients after allogeneic bone marrow transplant and response to granulocyte macrophage colony stimulating factor.

Normal human bone marrow was grown as xenografts in mice immune-suppressed by thymectomy and total body irradiation. Mononuclear cell fractions isolated from marrow harvests from 17 donors all gave rise to subcutaneous nodules which grew to a variable maximum size and then regressed. Human granulocyte/macrophage progenitors (CFU-GM) were recovered from xenografts up to 20 days postimplantation. Xenograft growth, measured by maximum nodule volume, area under the growth curve, and rate of regression, did not correlate with the speed of neutrophil or platelet recovery in bone marrow transplant patients infused with the same marrow. Assay of numbers of stromal fibroblastoid colony forming cells (CFU-F) in donor marrow was also not predictive of subsequent hemopoietic recovery in recipients. Treatment of host animals with daily intraperitoneal injections of 100 micrograms/kg human recombinant granulocyte/macrophage colony stimulating factor produced a more rapid growth of subcutaneous nodules. This technique may therefore be of use in determining the in vivo efficacy of human hemopoietic regulatory factors.