Experimental Studies On Malignant Transformation Of Bone Marrowmesenchymal Stem Cells Induced By Glioma Stem Cells

PartⅠ: Transformation ofmouse bone marrowmesenchymal stem cells induced by human glioma stem cells in vivoObjective: Both human glioma stem cell line SU3 transfected with red fluorescent protein(SU3-RFP) gene and bone marrowcells from enhanced green fluorescence protein(EGFP) transgenic athymic nude mice were transplanted intracerebrally into bone marrow damage- reconstitution Balb/c nude mice, to investigate the mutual interactions between bone marrow mesenchymal stem cells(BMSCs)and glioma stem cells(GSCs) in vivo. Methods: After irradiation of Balb/c athymic nude mice, allogeneic transplantation with EGFP+ bone marrow cells wasperformed via caudal vein injection, to establish a bone marrow damage-reconstitution model. Then SU3-RFP cells were transplanted intracranially. The xenograft tumors were harvested to sort and clone the high proliferative EGFP+ cells. The cell surface markers, biological characteristics and relevant gene analysis of the cloned EGFP+ cells were further analyzed.Results: The intracranialtumor formation rate of SU3-RFP cells in the bone marrow reconstitution model was 100%(7/7). High proliferative EGFP+ cells, with CD44, CD90, CD29 positive expression,and CD45 negative expression, were proved to be derived from BMSCs. Biological analysis showed these cells behaved high proliferation abilities and strong aggressiveness abilities,accompanied with over-expression of telomerase reverse transcriptase(TERT) gene, tumorigenicity rate was 100%(5/5)in Balb/c nude mice, which was named transformed bone mesenchymal stem cells(t BMSCs).Conclusion:Malignant transformation of BMSCs,induced by GSCs, can occur in dual-color-tracing tumor model, with over-expression of TERT, meanwhile, t BMSCs also participated the remodeling of tumorigenesis in bone marrow damage-reconstitution glioma model.Part Ⅱ: Comparative studies on biological characteristicsoft BMSCs and BMSCs stablely transfected with TERT in vitroObjective: To establish bone marrow mesenchymal stem cells(BMSCs) stablely transfected with telomerase reverse transcriptase(TERT),and compare with the transformed bone mesenchymal stem cells(t BMSCs).Methods: Primary culture of BMSCs from enhanced green fluorescence protein(EGFP) transgenic athymic Balb/c nude mice, then TERT gene was transfected into the BMSCs with TERT lentivirus expression vector.Comparative studies on the biological characteristics of TERT-BMSCs and t BMSCs were performed.Results: Proliferation abilities and aggressiveness abilities of t BMSCs were the highest, tumorigenicity rate of t BMSCs was 100%(5/5). Proliferation abilities and aggressiveness abilities of TERT-BMSCs were slightly lower than t BMSCs(P﹤0.05),its tumorigenicity rate was 20%(2/10), which was far below than that of t BMSCs; Proliferation abilities and aggressiveness abilities of normal BMSCs were far less than t BMSCs and TERT-BMSCs(P﹤0.01), its tumorigenesis rate was 0%(0/10).Conclusion:The mechanism of malignant transformation of bone marrowmesenchymal stem cells induced by glioma stem cells was not highly related with over-expression of TERT gene, but other gentic abnormalities may be involved in the malignant trans for mation processes.