Beneficial Effects of Exogenous Crosslinking Agents on Self-Assembled Tissue Engineered Cartilage Construct Biomechanical Properties

Abstract

Background As articular cartilage is unable to repair itself, there is a tremendous clinical need for a tissue engineered replacement tissue. Current tissue engineering efforts using the self-assembly process have demonstrated promising results, but the biomechanical properties remain at roughly 50% of native tissue. Methodology/Principal Findings The objective of this study was to determine the feasibility of using exogenous crosslinking agents to enhance the biomechanical properties of a scaffoldless cartilage tissue engineering approach. Four crosslinking agents (glutaraldehyde, ribose, genipin, and methylglyoxal) were applied each at a single concentration and single application time. It was determined that ribose application resulted in a significant 69% increase in Young's modulus, a significant 47% increase in ultimate tensile strength, as well as a trend toward a significant increase in aggregate modulus. Additionally, methylglyoxal application resulted in a significant 58% increase in Young's modulus. No treatments altered the biochemical content of the tissue. Conclusions/Significance To our knowledge, this is the first study to examine the use of exogenous crosslinking agents on any tissue formed using a scaffoldless tissue engineering approach. In particular, this study demonstrates that a one-time treatment with crosslinking agents can be employed effectively to enhance the biomechanical properties of tissue engineered articular cartilage. The results are exciting, as they demonstrate the feasibility of using exogenous crosslinking agents to enhance the biomechanical properties without the need for increased glycosaminoglycan (GAG) and collagen content.

Investigation of techniques for the measurement of articular cartilage surface roughness

“…Kääb et al, 1999) that prevents further degradation of tissue post mortem. The technique will increase the stiffness of specimens (Elder et al, 2011), however, the authors are unaware that it causes any changes to surface roughness. Fixing and dehydration of the cartilage is required for conventional scanning electron microscopy.…”

Characterisation of porcine dermis scaffolds decellularised using a novel non-enzymatic method for biomedical applications

“…26 Exogenous crosslinking agents, such as glutaraldehyde, ribose, formaldehyde, ethyl-(dimethyl aminopropyl) carbodiimide, and genipin have been used to enhance biomechanical properties of collagen-based biomaterial. 27,28 Amongst them, genipin seems to confer comparatively favourable mechanical properties and cell compatibility to scaffolds. 8,28 In our study, SEM examinations showed that genipin-crosslinked dermal scaffolds, as expected, had a more compact structure when compared to the noncrosslinked samples.…”

Temporal assessment of ribose treatment on self-assembled articular cartilage constructs

“…One technique that has been proposed to improve engineered tissue is the use of non-enzymatic glycation to induce collagen crosslinking [11–14]. Non-enzymatic glycation involves three steps [15].…”

“…Traditionally, the accumulation of AGEs has been understood to be an unwanted manifestation of aging and diabetes [15,17,18]. However, researchers have begun to recognize the potential benefits of non-enzymatic glycation as a tool to improve engineered tissue properties, especially without the risk of cytotoxicity posed by conventional crosslinking methods like glutaraldehyde fixation [11–14,19,20]. …”

“…In a recent experiment from our laboratory, self-assembled cartilage constructs were treated for 3.5 h with one of four exogenous crosslinking agents on the final day of construct culture ( t =28 days) [11]. A head-to-head comparison of treatments revealed that ribose produced the greatest improvements in tensile stiffness and strength, beating glutaraldehyde, genipin, and methylglyoxal.…”