Enhanced matrix synthesis in de novo, scaffold free cartilage-like tissue subjected to compression and shear

Abstract

Production of a de novo cartilage-like tissue construct is a goal for the repair of traumatic chondral defects. We aimed to enhance the matrix synthesis within a scaffold free, de novo cartilage-like tissue construct by way of mechanical load. A novel loading machine that enables the application of shear, as well as compression, was used to subject tissue engineered cartilage-like tissue to mechanical stress. The machine, which applies the load through a roller mechanism, can load up to 20 constructs with four different loading patterns simultaneously. The expression of mRNA encoding matrix products, and subsequent changes in matrix protein content, were analyzed after various loading regimes. The force applied to the immature tissue had a direct bearing on the short-term (first 4 h) response. A load of 0.5 N caused an increase in collagen II and aggrecan mRNA within an hour, with a peak at 2 h. This increased mRNA expression was translated into an increase of up to 60% in the glycosaminoglycan content of the optimally loaded constructs after 4 days of intermittent cyclical loading. Introducing pauses between load cycles reproducibly lead to an increase in GAG/DNA. In contrast, constant cyclical load, with no pause, lead to a decrease in the final glycosaminoglycan content compared with unloaded controls. Our data suggest that a protocol of mechanical stimulation, simulating in vivo conditions and involving shear and compression, may be a useful mechanism to enhance the properties of tissue engineered tissue prior to implantation.

Multi-axial mechanical stimulation of tissue engineered cartilage: Review

“…Although it is well known that chondrocytes are subjected to multi-axial forces in vivo (Mankin et al, 1994), the majority of these studies have only examined the effect of cyclic uniaxial loading (compression or shear). Some studies have investigated the effect of multi-directional simulated physiological loading (Wimmer et al, 2004;Grad et al, 2005;Grad et al, 2006;Stoddart et al, 2006); however, the applied strains (or stresses) are not easily quantifiable so it is difficult to correlate precisely the extent of multi-axial loading with changes in the growth of tissue engineered cartilage. However, there has been one report describing how equal-magnitude axial and transverse compression alters ECM synthesis but this study was done using cartilage explants (Heiner and Martin, 2004), which is different from in vitro-formed cartilage.…”

New perspectives for articular cartilage repair treatment through tissue engineering: A contemporary review

“…Advantages of this procedure are a more uniform cell distribution, avoidance of periosteal harvest and implantation, and increased technical ease without the need for suturing to adjacent articular cartilage. These scaffold-less platforms develop a robust ECM framework of their own and permit longterm maintenance of phenotype, at least in long-term in include hydrogels made from poly(ethylene glycol) diacrylate (PEGDA) [7,[11][12][13]41,42] , collagen [43] , fibrin [44,45] , agarose, and synthetic peptides [46,47] ; sponge-like scaffolds manufactured from materials such as collagen, polyglycolic acid, polylactic acid [48] , and polyurethane [49] ; materials with a naturally-occurring porous structure, such as coral, devitalized articular cartilage [50] , and hyaluronan based scaffolds [51] . The three-dimensional scaffold provides the structural support for cell contact and matrix deposition Musumeci G et vitro culture, and can improve biophysical properties by mechanical loading.…”

Scaffold-free Cartilage Tissue by Mechanical Stress Loading for Tissue Engineering

“…Therefore, probably shear stresses by rotational culture also reinforce the mechanical properties of our scaffold-free cartilage tissue. Recently, Elder et al reported an effect of hydrostatic pressures, and Stoddart et al (2006b) did an effect of of compressive force, on the formation of scaffold-free cartilage tissue from immature primary bovine chondrocytes. According to their studies, constant hydrostatic pressures of 5 and 10 MPa were more effective than oscilatory ones.…”