Mesenchymanl Stem Cell Based Intradiscal Gene Therapy: Therapeutic Implication in Degenerative Disc Disease

Abstract

Study Design: In-vitro experiments using human mesenchymal stem cells (MSCs), intervertebral disc (IVD) cells and type 5 adenovirus/transforming growth factor-β1 construct (Ad/TGF-β1). Objectives: To determine the effect of MSC-based gene therapy for matrix regeneration of IVD cells. Summary of Literature Review: MSCs are known to be multipotent in tissue regeneration. In degeneration of IVD, cellular replacement with genetic modification other than that of IVD cells may prove an enhanced mechanism for the regeneration of IVD cells. Materials and Methods: MSCs and IVD cells were cultured and an adenovirus construct containing TGF-β1 cDNA (Ad/TGF-β 1) was also produced. In the first step, the MSCs were transduced with Ad/TGF-β1, then mixed with IVD cells in various proportions and three dimensionally cultured. [methyl-H]Thymidine and [ S]Sulfur incorporation for DNA and proteoglycan synthesis, respectively, were measured. RT-PCR was performed to assess the aggrecan and collagen types I and II mRNA expressions Results: Mixed cultures of MSC and IVD cells showed relatively similar amounts of newly synthesized proteoglycan compared with cultures of IVD cells only. In mixed cultures transduced with Ad/TGF-β1, there were significant decreases in newly synthesized proteoglycan with increasing the proportions of MSCs, which was also found with the aggrecan and collagen type II mRNA expressions. However, the collagen type I mRNA expression increased with increased proportions of MSCs transduced with Ad/TGF-β1. Conclusion: Cell therapy with MSCs and IVD cells provided a mechanism for cellular augmentation. However, MSC-based gene therapy coupled with IVD cells did not maintain a chondrogenic phenotype.