Laboratory for Experimental Orthopaedics
Laboratory for Experimental Orthopaedics
left to right: Dieter Kohn, Gunter Kaul, Magali Cucchiarini, Tanja Thurn, Henning Madry
Articular cartilage, the tissue that forms the gliding surface of joints, has a poor regenerative capacity. The focus of our Laboratory is to study the regulation of articular cartilage metabolism and to apply therapeutic factors to enhance the repair of articular cartilage lesions. We have identified and optimized a lipid-based gene shuttle for efficient gene transfer into isolated articular chondrocytes (Madry et al., Gene Ther 2000). We next evaluated the effects of gene transfer of human insulin-like growth factor-I (IGF-I), a candidate gene mediating articular cartilage repair. Transplantation of articular chondrocytes overexpressing IGF-I led to the formation of a new tissue that was thicker and contained more cells than controls transfected with an lacZ expression plasmid vector. These results identified a molecular mechanism by which IGF-I simultaneously promotes chondrogenesis and shifts cartilage homeostasis in an anabolic direction (Madry et al., Gene Ther, 2001). When human fibroblast growth factor 2 (hFGF-2) was applied in this model, selective mitogenic activity was observed in the new tissue (Madry et al., J Gene Med, 2004).
Tissue engineering is a novel approach to modulate the formation of cartilage. Articular chondrocytes genetically modified to overexpress human IGF-I were seeded into polymer scaffolds, cultured in bioreactors and implanted subcutaneously in nude mice. After culture in the bioreactor, the structural and biomechanical properties of these IGF-I constructs were improved compared to control groups. The enhancement of chondrogenesis by spatially defined overexpression of human IGF-I suggests that cartilage tissue engineering based on genetically modified chondrocytes may be advantageous as compared to either gene transfer or tissue engineering alone (Madry et al., Hum Gene Ther, 2002).
We next investigated if transfected chondrocytes allow for sustained transgene expression when transplanted into sites of articular cartilage damage in vivo. In a model system where an osteochondral defect was created in the knee joints of rabbits, transgene expression remained present for at least 32 in vivo (Madry et al., J Gene Med, 2003).
Despite such promising progresses, no gene transfer vector system has been to date capable to directly penetrate the matrix in which the articular chondrocytes are embedded. Recombinant adeno-associated virus (rAAV) vectors based on the small non-pathogenic and replication-defective human parvovirus have been successfully employed in vivo by our group. In particular, we could demonstrate the property of rAAV to deeply penetrate solid tissues like the brain of rodents (Cucchiarini et al., Gene Ther, 2003). rAAV were thus tested for their ability to target cartilage. In explant cultures of articular cartilage, articular chondrocytes were successfully transduced in situ to a depth exceeding 450 µm that remained present until 150 days. When rAAV-lacZ vectors were applied to femoral chondral defects and osteochondral defects in vivo in a rat knee model, reporter gene expression was achieved for at least ten days following transduction (Madry et al., Hum Gene Ther, 2003).
We are currently investigating the effect of therapeutic factors involved in cartilage repair delivered to sites of articular cartilage damage by lipid-based and rAAV vectors. These data may be used to define the effects of genes involved in cartilage repair and may provide alternative treatments for articular cartilage.
Symposium: Trends in Molecular Orthopaedics
Wednesday, 29 May 2002
3.00 pm Stryker-Lecture:
Regulation of chondrocytes by growth factors
Stephen B. Trippel
Indianapolis, Indiana, USA
3.30 pm Meniscal Transplantation
3.45 pm Models to study musculo-skeletal microcirculation in health and disease
Michael D. Menger
4.00 pm Gene transfer for articular cartilage repair
4.15 pm Adeno-associated vectors for orthopaedic gene transfer applications
4.30 pm ACL replacement in sheep with open physes
4.45 pm The role of recombinant growth hormone in fracture healing
Michael J. Raschke
5.00 pm Bone morphogenetic proteins
5.15 pm Closing remarks
5.20 pm Wine and Cheese Reception
Henning Madry received his M.D. degree from Charité Medical School, Humboldt University in Berlin, Germany. He received the first part of his orthopaedic training at the Department of Trauma and Reconstructive Surgery, Charité Medical School. He pursued his postdoctoral training at Harvard Medical School and at the Massachusetts Institute of Technology, Cambridge, Massachusetts, USA. His research interests include musculo-skeletal gene transfer and tissue engineering.
Magali Cucchiarini received her Ph.D. degree from the Laboratory of Virology at the Faculty of Medicine, University of Nice-Sophia Antipolis in Nice, France. She pursued her postdoctoral training at the Laboratory of Internal Medicine, Inselspital, University of Bern, Switzerland and at Harvard Medical School and Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA. Her research interests include viral gene transfer and fundamental virology.