Collagen scaffolds for nonviral IGF-1 gene delivery in articular cartilage tissue engineering

Abstract

This study investigated the use of a type II collagenglycosaminoglycan (CG) scaffold as a nonviral gene delivery vehicle for facilitating gene transfer to seeded adult articular chondrocytes to produce an elevated, prolonged and local expression of insulin-like growth factor (IGF)-1 for enhancing cartilage regeneration. Gene-supplemented CG (GSCG) scaffolds were synthesized by two methods: (1) soaking a pre-cross-linked CG scaffold in a plasmid solution followed by a freeze-drying process, and (2) chemically cross-linking the plasmid DNA to the scaffold. Two different plasmid solutions were also compared: (1) naked plasmid IGF-1 alone, and (2) plasmid IGF-1 with a lipid transfection reagent. Plasmid release studies revealed that cross-linking the plasmid to the CG scaffold prevented passive bolus release of plasmid and resulted in vector release controlled by scaffold degradation. In chondrocyte-seeded GSCG scaffolds, prolonged and elevated IGF-1 expression was enhanced by using the cross-linking method of plasmid incorporation along with the addition of the transfection reagent. The sustained level of IGF-1 overexpression resulted in significantly higher amounts of tissue formation, chondrocyte-like cells, GAG accumulation, and type II collagen production, compared to control scaffolds. These findings demonstrate that CG scaffolds can serve as nonviral gene delivery vehicles of microgram amounts of IGF-1 plasmid (o10 mg per scaffold) to provide a locally sustained therapeutic level of overexpressed IGF-1, resulting in enhanced cartilage formation.

Treating Human Meniscal Fibrochondrocytes with hIGF-1 Gene by Liposome

“…It also plays an important role in stimulating collagen and proteoglycan synthesis in cartilage through an autocrine feedback mechanism [25]. Since hIGF-1 is a major chondro-enhancing agent, notwithstanding its attenuated effect on aged cartilage, it would appear a logical choice for gene therapy approaches [4,5,7,12,16]. It is a relatively small gene of approximately 45 kb pairs with the transcribed region spanning less than 1 kb, and the DNA sequence is known in most species.…”

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].…”

“…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].…”

 

“…Natural polymers should possess inherent biocompatibilities and bioactivities except for providing a suitable 3D environment for encapsulated and/or infiltrating cells. Natural polymers in common include hyaluronic acid (HA), [17][18][19] collagen, [8,9] alginate, [10,11] chitosan, [12] heparin, fibrin, cellu-lose, [13] and so on.…”