The distribution of donor cells during healing of incised wounds after allogeneic and syngeneic transplantation of whole bone marrow without irradiation, using mice carrying the EGFP gene

Abstract

Mesenchymal stem cells of bone marrow have been studied worldwide for their possible use in regenerative medicine. However, the knowledge about their interaction with cells and tissues of the recipient's body is still insufficient. The aim was to study the distribution of donor stem cells of whole bone marrow (BM) in the body of recipient animals and their contribution to wound healing depending on the kind of transplantation. Materials and methods. Mice carrying the green fluorescent protein (EGFP) gene were used as donors, and C57BL/6 and CBA mice were used as recipients. Syngeneic (from GFP+ to C57BL/6 mice) and allogeneic (from GFP+ to CBA mice) bone marrow transplantations (BMTs) were modeled without and with prior infliction of incised wounds in the interscapular zone. The rate of colonization of the wound area, thymus, spleen, BM, and blood with GFP+ cells was evaluated with a fluorescent microscope at 1, 3, 5, 7, 9, 11, and 14 days after the intravenous infusion of BM cells. The time of wound healing without and after BMT was determined and compared. Results. Populations of roundish GFP+ cells of all the studied organs and tissues, including the wound area, were observed in all animals on the next day after transplantation, with the exception of intact skin from the lumbar zone. After syngeneic transplantation, donor cells were observed during at least 14 days, while after allogeneic BMT, mostly during 3-5 days. At the same time, GFP+ fibroblasts were detected in the wound bed during 9 days after allogeneic BMT and at all timepoints of follow-up after syngeneic BMT. However, no differentiation of donor cells into cells of skin structural elements was found in the wound area. In the first instance, the rate of wound healing in the experiment was almost the same as in the control, and in the second instance, it was significantly higher than in the control (p = 0.0202, Mann-Whitney test). Conclusions. Оnly syngeneic BMT of whole bone marrow was effective after skin injuries, as it accelerated the healing. However, the lack of complete differentiation of donor cells during the treatment may indicate the absence or deficiency of necessary chemical signaling.