Ectopic models for endochondral ossification: comparing pellet and alginate bead culture methods.

Key aspects of native endochondral bone development and fracture healing can be mimicked in mesenchymal stem cells (MSCs) through standard in vitro chondrogenic induction. Exploiting this phenomenon has recently emerged as an attractive technique to engineer bone tissue, however, relatively little is known about the best conditions for doing so. The objective of the present study was to compare the bone-forming capacity and angiogenic induction of hypertrophic cell constructs containing human adipose-derived stem cells (hASCs) primed for chondrogenesis in two different culture systems: high-density pellets and alginate bead hydrogels.

Genipin crosslinking decreases the mechanical wear and biochemical degradation of impacted cartilage in vitro.

High energy trauma to cartilage causes surface fissures and microstructural damage, but the degree to which this damage renders the tissue more susceptible to wear and contributes to the progression of post-traumatic osteoarthritis (PTOA) is unknown. Additionally, no treatments are currently available to strengthen cartilage after joint trauma and to protect the tissue from subsequent degradation and wear. The purposes of this study were to investigate the role of mechanical damage in the degradation and wear of cartilage, to evaluate the effects of impact and subsequent genipin crosslinking on the changes in the viscoelastic parameters of articular cartilage, and to test the hypothesis that genipin crosslinking is an effective treatment to enhance the resistance to biochemical degradation and mechanical wear.

Genipin crosslinking of cartilage enhances resistance to biochemical degradation and mechanical wear.

Collagen crosslinking enhances many beneficial properties of articular cartilage, including resistance to chemical degradation and mechanical wear, but many crosslinking agents are cytotoxic. The purpose of this study was to evaluate the effectiveness of genipin, a crosslinking agent with favorable biocompatibility and cytotoxicity, as a potential treatment to prevent the degradation and wear of articular cartilage. First, the impact of genipin concentration and treatment duration on the viscoelastic properties of bovine articular cartilage was quantified.

The effect of collagen crosslinking on the biphasic poroviscoelastic cartilage properties determined from a semi-automated microindentation protocol for stress relaxation.

Given the important role of the collagenous structure in cartilage mechanics, there is considerable interest in the relationship between collagen crosslinking and the mechanical behavior of the cartilage matrix. While crosslink-induced alterations to the elastic modulus of cartilage have been described, changes to time-dependent behavior have not yet been determined. The objective of the study was to quantify changes to cartilage material properties, including viscoelastic coefficients, with crosslinking via indentation.

Methods to assess in vitro wear of articular cartilage.

New orthopedic implants for focal cartilage defects replace only a portion of the articulating joint and wear against the opposing cartilage surface. The objective of this study was to investigate different methodologies to quantify cartilage wear for future use in screening potential implant materials and finishes. In determining the optimal test parameters, two different cartilage surface geometries were compared: smaller specimens had a flat surface, while larger ones made contact in the center but not at the edge owing to the curvature of the articulating surface.