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 investigated in 41 patients who had received a sex-mismatched, T-cell-depleted allograft from human leukocyte antigen (HLA)-matched or -mismatched family donors. Polymerase chain reaction (PCR) analysis of the human androgen receptor (HUMARA) or the amelogenin genes was used to detect donor-derived mesenchymal cells. Only 14 marrow samples (34%) from 41 consenting patients generated a marrow stromal layer adequate for PCR analysis. Monocyte-mecrophage contamination of marrow stromal layers was reduced below the levels of sensitivity of HUMARA and amelogenin assays (5% and 3%, respectively) by repeated trypsinizations and treatment with the leucyl-leucine (leu-leu) methyl ester. Patients who received allogrsfts from 12 female donors were analyzed by means of the HUMARA assay, and in 5 of 12 cases a partial female origin of stmmal cells was demonstrated. Two patients who received amlograffs from male donors were analyzed by amplifying the ameloganin gane, and in both cases a partial male origin of stromal cells was shown. Fluorescent in situ hybridization analysis using a Y probe confirmed the results of PCR analysis and demonstrated in 2 cases the existence of a mixed chimerism at the stromal 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 10⁴/kg vs 1.19 ± 0.19 x 10⁴/kg; P ≥ .97). In conclusion, marrow stromal progenitors reinfused in patients receiving a T-cell-depleted allograft have a limited capacity of reconstituting marrow mesenchymal cells. (C) 2000 by The American Society of Hematology.