Allogeneic Non-Adherent Bone Marrow Cells Facilitate Hematopoietic Recovery but Do Not Lead to Allogeneic Engraftment

Abstract

BackgroundNon adherent bone marrow derived cells (NA-BMCs) have recently been described to give rise to multiple mesenchymal phenotypes and have an impact in tissue regeneration. Therefore, the effects of murine bone marrow derived NA-BMCs were investigated with regard to engraftment capacities in allogeneic and syngeneic stem cell transplantation using transgenic, human CD4+, murine CD4−/−, HLA-DR3+ mice.Methodology/Principal FindingsBone marrow cells were harvested from C57Bl/6 and Balb/c wild-type mice, expanded to NA-BMCs for 4 days and characterized by flow cytometry before transplantation in lethally irradiated recipient mice. Chimerism was detected using flow cytometry for MHC-I (H-2D[b], H-2K[d]), mu/huCD4, and huHLA-DR3). Culturing of bone marrow cells in a dexamethasone containing DMEM medium induced expansion of non adherent cells expressing CD11b, CD45, and CD90. Analysis of the CD45+ showed depletion of CD4+, CD8+, CD19+, and CD117+ cells. Expanded syngeneic and allogeneic NA-BMCs were transplanted into triple transgenic mice. Syngeneic NA-BMCs protected 83% of mice from death (n = 8, CD4+ donor chimerism of 5.8±2.4% [day 40], P<.001). Allogeneic NA-BMCs preserved 62.5% (n = 8) of mice from death without detectable hematopoietic donor chimerism. Transplantation of syngeneic bone marrow cells preserved 100%, transplantation of allogeneic bone marrow cells 33% of mice from death.Conclusions/SignificanceNA-BMCs triggered endogenous hematopoiesis and induced faster recovery compared to bone marrow controls. These findings may be of relevance in the refinement of strategies in the treatment of hematological malignancies.

Allogeneic bone marrow grafts with high levels of CD4+CD25+FoxP3+ T cells can lead to engraftment failure

“…We found a faster reconstitution of hematopoiesis in ORIGINAL ARTICLE co-transplanted animals indicating a supportive effect of syngeneic T regs . In both groups, the reconstitution of lymphocytes was later than the reconstitution of monocytes and granulocytes indicating a normal reconstitution of the hematopoietic system in this model (21). Further investigation was essential whether the recovery of hematopoiesis is host or donor derived after syngeneic transplantation.…”

“…It has been demonstrated that both, cytokine mediated as well as cell contact dependent mechanisms, play important roles for the effects of the T regs . We analyzed the influence of T regs in a co-transplantation setting using a triple transgenic (TTG) transplantation model as we previously described (21)(22)(23). Flow cytometry plays a key role for characterization and determination of cells after HSCT and is used in different transplantation models (24)(25)(26).…”

Flow cytometric analysis of the graft‐versus‐Leukemia‐Effect After Hematopoietic Stem Cell Transplantation in Mice

“…As mentioned earlier, the experiments described in this work stand in close relation to a TTG transplantation model previously described , which attempts to prevent the development of aGvHD. Contrary to most CD4 antibodies, MAX.16H5 IgG 1 is a nondepleting antibody, which modulates T‐cells, in a manner that is not yet completely understood.…”

Characterization of murine non-adherent bone marrow cells leading to recovery of endogenous hematopoiesis

“…For transplantation, we used the TTG transplantation model as we have already described elsewhere [2]. These mice have a stable C57Bl/6 background in which the murine CD4 molecule is knocked out and replaced by human CD4 [9,10].…”

“…and CD117/ CD90 low? cells [2]. It has been shown elsewhere that NA-BMCs could differentiate into hematopoietic and stromal cell lineages [3] and are also a major source for adult stem cells [4].…”