Human umbilical cord blood-derived mesenchymal stem cells restored hematopoiesis by improving radiation induced bone marrow niche remodeling in rats.

Background: Functional hematopoiesis is governed by the bone marrow (BM) niche, which is compromised by radiotherapy, leading to radiation induced BM failure. The aim of this study was to demonstrate the radiation induced pathological remodeling of the niche and the efficacy of human umbilical cord blood-derived mesenchymal stem cells (hUCB-MSCs) in restoring hematopoiesis via improvement of the niche.

Methods: Thirty male Wistar rats were equally assigned to three groups: control (CON), irradiated (IR), and IR+hUCB-MSCs. Biochemical, histopathological and immunohistochemical analyses were performed to detect collagen type III and IV, Aquaporin 1 sinusoidal endothelial cells and immature hematopoietic cells, CD11c dendritic cells, Iba1 macrophages, CD9 megakaryocytes, Sca-1, cKit, CD133 and N-cadherin hematopoietic stem and progenitor cells, CD20, Gr1 mature hematopoietic cells, in addition to ki67 proliferation, Bcl-2 anti-apoptotic, caspase-3 apoptotic, TNF-α inflammatory cells. Histoplanimetry data were statistically analyzed using the one-way analysis of variance followed by the post hoc Duncan's test. Moreover, Pearson's correlation was used to assess the correlation between various parameters.

Results: In comparison to the IR group, the IR+hUCB-MSCs group showed restored cell populations and extracellular collagen components of the BM niche with significant increase in hematopoietic stem, progenitor, mature and proliferating cells, and a considerable decrease in apoptotic and inflammatory cells. Furthermore, highly significant correlations between BM niche and blood biochemical, histopathological, and immunohistochemical parameters were observed.

Conclusion: hUCB-MSCs restored functional hematopoiesis through amelioration of the BM niche components via reduction of oxidative stress, DNA damage, inflammation, and apoptosis with upregulation of cellular proliferation.