title: Differentiation of GFP-Bcl-2-engineered mesenchymal stem cells towards a nucleus pulposus-like phenotype under hypoxia in vitro.
abstract: Differentiation of bone marrow-derived mesenchymal stem cells (MSCs) into a nucleus pulposus-like phenotype under hypoxia has been proposed as a potential therapeutic approach for intervertebral disc degeneration. However, limited cell viability under hypoxic conditions has restricted MSC differentiation capacity and thus restricted its clinical application. In this study, we genetically modified MSCs with an anti-apoptotic GFP-Bcl-2 gene and evaluated cell survival and functional improvement under hypoxia in vitro. Rat bone marrow MSCs were transfected by lentiviral vectors with the GFP-Bcl-2 gene (GFP-Bcl-2-MSCs). Cell proliferation and apoptosis were assessed, and semi-quantitative reverse transcription polymerase chain reaction (RT-PCR) was carried out to evaluate phenotypic and biosynthetic activities. In addition, Alcian blue staining was used to detect the formation of sulfated glycosaminoglycans (GAGs) in the differentiated cells. We found that the Bcl-2 gene protected MSCs against apoptosis. We also observed that Bcl-2 over-expression reduced apoptosis by 40.61% in non-transfected MSCs and 38.43% in vector-MSCs to 18.33% in Bcl-2-MSCs. At 3days, the number of viable Bcl-2-MSCs was approximately two times higher than the number of MSCs or vector-MSCs under hypoxic conditions. RT-PCR showed higher expression of chondrocyte-related genes (Sox-9, aggrecan and type II collagen) in GFP-Bcl-2-MSCs cultured under hypoxia. The accumulation of proteoglycans in the pellet was 86% higher in GFP-Bcl-2-MSCs than in the control groups. Furthermore, the ratio of proteoglycans/collagen II in GFP-Bcl-2-MSCs was 6.2-fold higher compared to the MSC and vector-MSC groups, which denoted a nucleus pulposus-like differentiation phenotype. Our findings support the hypothesis that anti-apoptotic gene-modified MSCs can differentiate into cells with a nucleus pulposus-like phenotype in vitro, which may have value for the regeneration of intervertebral discs using cell transplantation therapy.
authors: Department of Orthopaedics, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, PR China.
authors: Zhong
authors: Z
authors: Fang
authors: Qin
authors: Q
authors: Yang
authors: Wei
authors: W
authors: Luo
authors: Guang-hui
authors: GH
authors: Li
authors: Jun
authors: J
authors: Xiao
authors: Feng
authors: F
authors: Li
authors: Wei
authors: W
authors: Xiong
mesh_terms: D000818:Animals; D017209:Apoptosis; D002454:Cell Differentiation; D015687:Cell Hypoxia; D002478:Cells, Cultured; D005818:Genetic Engineering; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D007403:Intervertebral Disc / Q000166:cytology* / Q000502:physiology; D045164:Mesenchymal Stem Cell Transplantation; D059630:Mesenchymal Stem Cells / Q000166:cytology* / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000235:genetics / Q000378:metabolism*; D051381:Rats; D012038:Regeneration; D023822:Tissue Engineering / Q000379:methods*
chemical_list: D019253:Proto-Oncogene Proteins c-bcl-2; D049452:Green Fluorescent Proteins