Abstract
BackgroundArticular cartilage has a limited potential for self-healing. Transplantation of genetically modified progenitor cells like bone marrow-derived mesenchymal stem cells (MSCs) is an attractive strategy to improve the intrinsic repair capacities of damaged articular cartilage.MethodsIn this study, we examined the potential benefits of co-overexpressing the pleiotropic transformation growth factor beta (TGF-β) with the cartilage-specific transcription factor SOX9 via gene transfer with recombinant adeno-associated virus (rAAV) vectors upon the biological activities of human MSCs (hMSCs). Freshly isolated hMSCs were transduced over time with separate rAAV vectors carrying either TGF-β or sox9 in chondrogenically-induced aggregate cultures to evaluate the efficacy and duration of transgene expression and to monitor the effects of rAAV-mediated genetic modification upon the cellular activities (proliferation, matrix synthesis) and chondrogenic differentiation potency compared with control conditions (lacZ treatment, sequential transductions).ResultsSignificant, prolonged TGF-β/sox9 co-overexpression was achieved in chondrogenically-induced hMSCs upon co-transduction via rAAV for up to 21 days, leading to enhanced proliferative, biosynthetic, and chondrogenic activities relative to control treatments, especially when co-applying the candidate vectors at the highest vector doses tested. Optimal co-administration of TGF-β with sox9 also advantageously reduced hypertrophic differentiation of the cells in the conditions applied here.ConclusionThe present findings demonstrate the possibility of modifying MSCs by combined therapeutic gene transfer as potent future strategies for implantation in clinically relevant animal models of cartilage defects in vivo.
Highlights
Articular cartilage has a limited potential for self-healing
For the first time to our best knowledge, we evaluated the possibility of codelivering Transforming growth factor beta (TGF-β) and SOX9, two of the most potent chondrogenic factors [29,30,31,32,33], to primary Human bone marrow-derived mesenchymal stem cell (hMSC) as a means to stimulate the chondroreparative activities of such cells as a thorough extension of our previous work using independent application of these agents [22, 23]
Effective and sustained TGF-β and sox9 co-overexpression in chondrogenically-induced hMSC aggregate cultures via combined recombinant adeno-associated virus (rAAV)-mediated gene transfer hMSCs were first transduced with the various rAAV vectors and vector combinations in chondrogenically-induced aggregate cultures as presented in Fig. 1 to evaluate the ability of this vector class to promote the co-expression of the chondrogenic TGF-β and sox9 genes over time in cells committed toward the chondrocyte phenotype compared with control conditions
Summary
Articular cartilage has a limited potential for self-healing. Transplantation of genetically modified progenitor cells like bone marrow-derived mesenchymal stem cells (MSCs) is an attractive strategy to improve the intrinsic repair capacities of damaged articular cartilage. While administration of bone marrow-derived mesenchymal stem cells (MSCs), an attractive source of cells for regenerative purposes, has been already attempted in patients to activate the regenerative processes in focal cartilage defects [2, 5,6,7,8,9,10], the outcomes have not been consistently associated with the formation of functional, hyaline-like repair tissue that fully and stably integrates with the surrounding, intact cartilage. Reports from diverse groups showed that multiple therapeutic gene transfer might be more valuable to stimulate the repair activities in these cells relative to independent treatments [13, 17, 21, 25,26,27], a finding described by us in human articular chondrocytes [28]
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