Anin vivo mouse model for human cartilage regeneration

Abstract

Cartilage regeneration methods have been examined in various animal models. The major limitation of those studies is the biological difference between human and animal cartilage. We propose an in vivo model for human chondrocytes in a human cartilage defect environment. Human full-thickness (2-4 mm) articular cartilage discs (diameter 10 mm) attached to 3-6 mm subchondral bone, were obtained from human femur heads. Chondral defects (diameter 4 mm) were set within the cartilage disc without violating the subchondral bone. Human chondrocytes were isolated, cultivated for three passages and then suspended at a concentration of 10(7) cells/ml. The defect was completely filled with the cell suspension (approximately 30 microl) and then covered with a thin sheet of human periosteum, fixed with fibrin sealant. Discs were implanted subcutaneously in the backs of nude mice for 5 and 8 weeks. Controls were uncovered discs filled with cell suspension and covered discs without cells. Histological evaluation revealed a gradient of differentiation from the cartilage lateral side to the centre of the defect. A proteoglycan-rich matrix was formed with some chondron-like structures at the border of native cartilage, whereas fibrous tissue was built in the centre of the defect. After 8 weeks the areas of differentiating cells enlarged compared to 5 weeks, indicating the progress of cartilage repair. The control discs without cells or cover showed no chondrogenesis. Interestingly, uncovered discs filled with cells showed comparable areas of differentiating cells at the defect surface but lack of fibrous tissue in the middle. The histological results were supported by MRI measurement.

Three-Dimensional Magnetic Resonance Observation of Cartilage Repair Tissue (MOCART) Score Assessed With an Isotropic Three-Dimensional True Fast Imaging With Steady-State Precession Sequence at 3.0 Tesla

“…Available studies prove a gradient of differentiation of the cartilage repair tissue from peripheral to central within in vivo mouse models. 42,43 Furthermore, the quality of articular cartilage repair seems to be strongly influenced by its mechanical environment and its relation to full weight bearing. 44 The impact of the localization of the described pathology becomes visible when looking at Figure 2, where an underfilling as well as a cleft formation is obvious, though not within the area of maximum weight bearing.…”

Polysaccharide-based materials for cartilage tissue engineering applications

“…The size and shape of the tissue to be regenerated, the nature and type of the cartilage defect and the conditions of the host should also be considered in the selection of materials (Chang et al , 2001; Hunziker, 2002; Temenoff et al , 2000; Vacanti et al , 1998). Different types of natural and synthetic materials have been used to fabricate supports for cartilage tissue engineering (Awad et al , 2004; Brandl et al , 2007; Bryant et al , 2004; Dunkelman et al , 1995; Gugala et al , 2000; Lee et al , 2000; Malafaya et al , 2005; Perka et al , 2000), Examples of the first type are fibrin (Perka et al , 2000; Schuller et al , 2008), collagen (Lee et al , 2000), alginate (Awad et al , 2004; Chang et al , 2001) and chitosan (Hoemann et al , 2005; Malafaya et al , 2005), and of the latter polyglycolic acid (Wang et al , 2003), polylactic acid (Gugala et al , 2000) and polyethylene glycol (Bryant et al , 2004). Natural and synthetic materials present both advantages and disadvantages.…”

Novel injectable gel (system) as a vehicle for human articular chondrocytes in cartilage tissue regeneration

“…Nevertheless, in the case of cartilage engineering, one of the major limitations of this method is the lack of an appropriate articular cartilage surrounding the newly formed tissue, and therefore the impossibility of investigating the integration of the newly formed cartilage with the pre-existing cartilage. We used an organ culture model, recently described (Mueller-Rath et al, 2007;Schuller et al, 2008), in which the hydrogel, including encapsulated HACs, was directly injected into the defect created on the surface of the bovine articular cartilage layer (Figure 7). The cartilage biopsy with the hydrogel was maintained in culture in chondrogenic medium for 1 week, then implanted subcutaneously in the immunodeficient mouse.…”

“…The aim of this study was to investigate some of these aspects in the case of a new biodegradable carrageenanbased injectable gel. Recent papers described a new organ culture model in which human articular chondrocytes were cultured within an experimentally made osteochondral defect in an articular cartilage biopsy subcutaneously implanted in an immunodeficient mouse (Mueller-Rath et al, 2007;Schuller et al, 2008). We adopted a similar approach to show that carrageenan-based hydrogel, seeded with human articular chondrocytes (HACs), has the potential to regenerate and repair an articular defect.…”