Regional gene therapy for full‐thickness articular cartilage lesions using naked DNA with a collagen matrix

Abstract

A novel gene therapy approach for treating damaged cartilage is proposed that involves placing endotoxin-free cDNA containing the gene for bone morphogenetic protein-2 (BMP-2) in type I collagen sponges and then transferring the naked plasmid DNA construct to the injury site. A fullthickness cartilaginous defect in rabbits implanted with plasmid containing a marker gene (bgalactosidase) showed expressed protein as detected by immunostaining. At 1 week postimplantation, mesenchymal cells subjacent to the defect had incorporated the implanted naked plasmid DNA and, once transfected, served as local bioreactors, transiently producing the gene product. Plasmids containing the gene for BMP-2 implanted in collagen sponges in cartilage lesions stimulated hyalinelike articular cartilage repair at 12 weeks postimplantation, nearly equivalent in quality to that induced by collagen sponges with recombinant BMP-2 protein. Our approach circumvents the risks of inflammation and immunogenic response associated with the use of viral vectors. Naked plasmid DNA as a vehicle for transferring therapeutic genes has been shown to be effective in a therapeutic model within rabbit articular cartilage and appears to be safe and cost effective. ß

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

“…They can deliver large genes and are easy to produce on a large scale. In addition, polymeric gene therapy is employed to delivery genes without transfecting cells, by complexing the plasmid with (a) a branched poly(ethylenimine)-hyaluronic acid (bPEI-HA) delivery vector, via a porous oligo-[poly(ethylene glycol) fumarate] hydrogel scaffold; (b) type I collagen gels, or (c) collagen-glycosaminoglycan scaffold in vivo by electrotransfer [12,[22][23][24].…”

“…Such genes are insulin-like growth factor 1 (IGF-1) [15-18, 20, 23, 25], transforming growth factor β (TGF-β) [14,26,27], bone morphogenetic proteins (BMPs) [20,22] and fibroblast growth factor 2 (FGF-2) [16,18,21]. Other genes belong to the transcription factors family, SRY-related HMG box (SOX) [24], the anti-inflammatory cytokine Interleukin 10 (IL10) [12] and cartilage oligomeric matrix protein (COMP), a ECM component [19] (Table 1).…”

“…The cell vehicles, with and without scaffolds, are MSCs of different origin [14, 17, 26, 27, 40-42, 46, 54, 55, 59, 61, 71-75, 77, 82], chondrocytes [16,21,44,59,61,62,70,83] and, to a lesser extent, fibroblasts [18,56]. In fewer cases vectors are implanted into scaffolds without cells as vehicles: the plasmid vector is supported by a collagen I sponge or complexed with bPEI-HA via a porous oligo[poly(ethylene glycol) fumarate] hydrogel scaffold [22,24] and adenoviral vector by DCBM [51] (Table 1).…”

“…When the scaffold is degraded, the encapsulated expression vector is adsorbed locally by the cells. The combination of gene therapy and scaffolds seems to greatly enhance both the efficiency and duration of transfected genes, leading to systems able to promote bone, cartilage, and osteochondral regeneration [22,23,26]. Scaffolds can be natural such as DBM, gelatine, alginate, fibrinogen and collagen based [16-18, 21, 27, 46, 52, 62, 71, 73, 84], or synthetic such as polyglycolic acid (PGA), polylactic acid (PLA) and poly(lactic-co-glycolide) (PLGA) [14,42,54,[82][83][84] (Table 1).…”

“…Besides favouring cell engineering within the scaffold, their design can be used as guide for the correct integration and directional localization of cells in the defect. Although there have been important advances in the creation of these systems, different factors, such as kinetic of release, type of interaction of the vector with the scaffold, or interactions between scaffolds and microenvironment, can still be improved [22,23,84].…”