1. ¹Department of Orthopaedic Surgery, University of Pittsburgh, Pittsburgh, PA, USA
2. ²Department of Surgery, The Brooklyn Hospital Center, Brooklyn, NY, USA
3. ³Division of Molecular Pharmaceutics, University of North Carolina School of Pharmacy, Chapel Hill, NC, USA

Correspondence: Dr CR Chu, Cartilage Restoration Laboratory, Department of Orthopaedic Surgery, University of Pittsburgh, 5200 Centre Ave; Suite 415, Pittsburgh, PA 15232, USA. E-mail: chucr@upmc.edu

Received 8 October 2006; Revised 15 January 2007; Accepted 15 January 2007; Published online 8 March 2007.

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-1)-transduced hMSC can improve cartilage repair in vivo. Adult hMSC were transduced with AAV-green fluorescent protein (GFP) or AAV-transforming growth factor 1 (TGF1) and studied in pellet cultures. For in vivo studies, AAV–GFP and AAV–TGF-1-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-1-transduced hMSC at 12 weeks (P=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.