Limited engraftment capacity of bone marrow-derived mesenchymal cells following T-cell-depleted hematopoietic stem cell transplantation

The engraftment capacity of bone marrow-derived mesenchymal cells was inves tigated in 41 patients who had received a sex-mismatched, T-cell-depleted a llograft from human leukocyte antigen (HLA) matched or -mismatched family d onors. Polymerase chain reaction (PCR) analysis of the human androgen recep tor (HUMARA) or the amelogenin genes was used to detect donor-derived mesen chymal cells. Only 14 marrow samples (34%) from 41 consenting patients gene rated a marrow stromal layer adequate for PCR analysis. Monocyte-macrophage contamination of marrow stromal layers was reduced below the levels of sen sitivity of HUMARA and amelogenin assays (5% and 3%, respectively) by repea ted trypsinizations and treatment with the leucyl-leucine (leu-leu) methyl ester, Patients who received allografts from 12 female donors were analyzed by means of the HUMARA assay, and in 5 of 12 cases a partial female origin of stromal cells was demonstrated. Two patients who received allografts fr om male donors were analyzed by amplifying the amelogenin gene, and in both cases a partial male origin of stromal cells was shown. Fluorescent in sit u hybridization analysis using a Y probe confirmed the results of PCR analy sis and demonstrated in 2 cases the existence of a mixed chimerism at the s tromal cell level. There was no statistical difference detected between the dose of fibroblast progenitors (colony-forming unit-F [CFU-F]) infused to patients with donor- or host-derived stromal cells (1.18 +/- 0.13 x 10(4)/k g vs 1.19 +/- 0.19 x 10(4)/kg; P greater than or equal to .97). In conclusi on, marrow stromal progenitors reinfused in patients receiving a T-cell-dep leted allograft have a limited capacity of reconstituting marrow mesenchyma l cells. (C) 2000 by The American Society of Hematology.