Adeno-associated viral gene transfer of transforming growth factor-β1 to human mesenchymal stem cells improves cartilage repair

Abstract

Bone marrow cells are routinely accessed clinically for cartilage repair. This study was performed to determine whether adeno-associated virus (AAV) effectively transduces human bone marrow-derived mesenchymal stem cells (hMSC) in vitro, whether AAV infection interferes with hMSC chondrogenesis and whether AAV-transforming growth factor-beta-1 (TGF-b1)-transduced hMSC can improve cartilage repair in vivo. Adult hMSC were transduced with AAVgreen fluorescent protein (GFP) or AAV-transforming growth factor b1 (TGFb1) and studied in pellet cultures. For in vivo studies, AAV-GFP and AAV-TGF-b1-transduced hMSCs were implanted into osteochondral defects of 21 athymic rats. GFP was detected using fluorescent microscopy.Cartilage repair was assessed using gross and histological analysis at 4, 8 and 12 weeks. In pellet culture, GFP expression was visualized in situ through 21 days in vitro. In vivo GFP transgene expression was observed by in situ fluorescent surface imaging in 100% of GFP implanted defects at 2 , 67% at 8 and 17% at 12 weeks. Improved cartilage repair was observed in osteochondral defects implanted with AAV-TGF-b1-transduced hMSC at 12 weeks (P ¼ 0.0047). These results show that AAV is a suitable vector for gene delivery to improve the cartilage repair potential of human mesenchymal stem cells.

Articular cartilage repair by genetically modified bone marrow aspirate in sheep

“…Guo et al 32 reported similar results in a rabbit model of full-thickness cartilage defects using an ex vivo approach and a chitosan scaffold. Another study by Pagnotto et al 33 showed improved cartilage repair in osteochondral defects implanted with MSCs transduced with adeno-associated virus (AAV) carrying cDNA for TGF-b1. In their study, transgene expression slowly decreased from 100% at 2 weeks to 17% at 12 weeks, but it proved that gene therapy enables sustained delivery of the bioactive molecules for a period of time that is sufficient to induce and govern cellular response within the defect.…”

Progress and Prospects: genetic treatments for disorders of bones and joints

“…In a similar study, AAV was used to transfer TGF-b 1 cDNA into human MSCs, which were subsequently implanted into osteochondral defects in nude rats. 41 Healing was superior to that achieved with negative control GFP cDNA. It was noted that, by 12 weeks only 12% of the cells within the defect were GFP + .…”

Gene therapy for chondral and osteochondral regeneration: is the future now?

“…More than 50 adenovirus serotypes are available for gene therapy and serotype 5 (Ad5) has been the mostly used in both in vitro and in vivo studies. Adenovirus is used to transfer GF genes (TGF-β, FGF-2, IGF-1, BMPs and Growth and differentiation factor 5, GDF-5) into cells [8,20,25,[40][41][42][43][44][45][46][47][48][49]. Genes, in encapsuled viral [24] vector, can be injected directly in vivo [50,51] or through decalcified cortical bone matrix (DCBM) as scaffold that contains the viral particles [52].…”