Genetic safety evaluation of allogeneic bone marrow mesenchymal stem cells in hosts following traumatic brain injury / 中华神经医学杂志

ABSTRACT

Objective:To investigate the genetic safety of allogeneic bone marrow mesenchymal stem cells (BMSCs) transplantation in traumatic brain injury (TBI).Methods:(1) In vivo experiment: BMSCs from male SD rats were isolated and cultured. Moderate TBI models were prepared by implanting and fixing micro-drug injection cannula into the left ventricle of 12 female SD rats, and 3 d after that, striking the right cerebral cortex of the rats with pneumatic precision percussion device was performed. Four h, and 3, 6, 9, and 12 d after modeling, TBI rats were given a single/multiple BMSCs infusion (2.5×10 5/time, total volume 10 μL) by cannula; 48 and 72 h, and 10 and 14 d after modeling, brain tissues of TBI rats (3 at each time point) were prepared into paraffin specimens. Immunofluorescent staining was used to detect the microglia activation, and RNAscope ? technology was used to detect the co-localization of astrocytes, neurons, microglia and transplanted BMSCs to observe whether the allogeneic BMSCs were integrated with the host brain cells after transplantation into TBI host. (2) In vitro experiment: the frozen and revived microglial cell line BV2 was transfected with green fluorescent protein (GFP)-positive lentiviral particles, and then, BMSCs prelabeled with pHrodo RED probe and BV2 cells pretreated with lipopolysaccharide were co-cultured in a certain ratio (BV2:BMSCs=1:1, 1:2, 2:1); after 36 and 72 h of co-culture, the phagocytosis between the 2 kinds of cells was observed under confocal fluorescence inverted microscope to observe the specific action forms of microglia on BMSCs. Results:(1) In vivo experiment: 48 and 72 h, and 10 and 14 d after modeling, no colocalization of transplanted BMSCs with astrocytes or neurons was found in paraffin sections of brain tissue in TBI rats; however, 10 and 14 d after modeling, microglia in TBI rats were obviously activated and migrated to the left lateral ventricle and choroid plexus, and co-localization of microglia with transplanted BMSCs was observed. (2) In vitro experiment: phagocytosis occurred after co-culture of BV2 cells at different proportions with BMSCs for 36 and 72 h. Conclusion:After transplantation, allogeneic BMSCs do not integrate with astrocytes or neurons of the TBI host, but they could be phagocytosed by microglia, indicating that allogeneic BMSCs transplantation for TBI is genetically safe.