MSCs as a Vector of Gene Engineering

Abstract

AbstractIntroduction of transgene of interest into autologous stem cell types poses an attractive cell-based delivery strategy. Gene delivery to MSCs has been proposed as a mechanism to promote the augmentation of tissue-engineered replacement systems. MSCs are attractive targets for gene delivery systems, because they can differentiate, in response to various molecular signals, into many types of committed cells. MSCs divide rapidly and are readily transducible with integrating vectors and maintain transgene expression in vitro and in vivo without affecting multipotentiality. The unique biology of MSCs predetermines them to become valuable cytoreagents for gene therapy approaches in future. This chapter briefly describes the application of MSCs in genetic engineering according to the category of vectors and desired nucleic acid.Genetically modified mesenchymal stem cells (MSCs) are a valuable tool for the novel treatment of human diseases, especially in the heart. MSCs are pluripotent cells that are considered an important resource for human cell-based therapies. Gene transference into MSCs with subsequent expression has become a valuable tool for physiological studies, functional genomics and gene therapy. Furthermore, ectopic expression of signaling molecules and transcription factors is useful for manipulating the differentiation, immigration and apoptosis of cells. It is a key factor in choosing suitable recipient cells for successful gene therapy. Recipient cells for gene therapy should be easily acquired and cultured and have a long lifespan. Recently, on account of these requirements, scientists have begun to pay more attention to stem cells, such as embryonic stem cell (ESC), hematopoietic stem cell (HSC) and MSC, etc. MSCs have some advantages over other kinds of stem cells; they are readily obtained from bone marrow, are easily isolated and expanded ex vivio, they have low immunogenicity with regards to engraft rejection, and their use is unrestricted by ethics. It has also demonstrated from a series of animal studies that MSCs can be regarded as ideal candidates for target gene transfection and expression.The common vectors of gene engineering include viral vectors and nonviral vectors, such as retrovirus, adenovirus, lentivirus, liposomes and plasmids, etc. The caveat concerning the combination of gene and cell therapy is whether vectors can confer transgenic expression to the host cells without any cytotoxicity. Generally, MSCs are easily transfected and carry exogenous genes with a relatively high expression. McMahon and colleagues had compared the efficiency of a broad range of both viral and nonviral vectors at delivering green fluorescent protein (GFP) reporter gene into rat MSCs as well as determining the effect of these procedures on cell survival (McMahon et al, 2006). Lentivirus proved to be most effective with transfection efficiencies of up to 95%, and concurrent with low cytotoxicity. Adenovirus also proved effective, but a significant increase in cell death was seen with increasing viral titration. Rat MSCs remained refractory to transduction by all adeno-associated virus (AAV) serotypes, in contrast to rabbit MSCs tested at the same time. Approximately 93% of MSCs transfected by AAV could express target genes and the related proteins. Retrovirus is able to transfect MSCs quite easily, but the efficiency is decreased to 50%≈80%. Lipofection of plasmid DNA gave moderate transduction levels but was also accompanied by cell death. Electroporative gene transfer proved ineffective at the parameters tested and resulted in high cell death. Cationic lipid-mediated transduction had been demonstrated to be highly ineffective as well as causing serious cytotoxicity to MSCs. High and moderate levels of cell transfection using lentivirus vectors did not affect the ability of the cells to differentiate down the adipogenic pathway. In summary, lentivirus might be the best vector for transfection in MSCs.According to different target genes and their vectors, we will briefly introduce the application of MSCs in genetic engineering.KeywordsVascular Endothelial Growth FactorMesenchymal Stem CellNonviral VectorVascular Endothelial Growth Factor GroupExpress Target GeneThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.