Cartilage Tissue Engineering

Produced a research poster summarizing findings and presented at the Canadian Connective Tissue Conference, 2023.

Objective

Osteoarthritis (OA) affects 1 in 5 Canadians and results from progressive cartilage degradation [1]. Because cartilage has limited ability to repair itself, tissue engineering approaches aim to create engineered cartilage that is stable and resistant to inflammatory damage. Myokines, muscle-derived signaling molecules, have been shown to promote this resistance [2]. This project explored the role of irisin, a newly discovered myokine, in protecting engineered cartilage against inflammation caused by the cytokine IL-1β [3].

Figure 1 - Proposed mechanism of muscle-derived factors on early OA pathogenesis which is largely mediated by pro-inflammatory cytokines TNF-α , IL-1β.

Methods

• Cartilage-like tissues were engineered from primary bovine articular chondrocytes.

• Cells were cultured in chondrogenic media for 20 days.

• At Day 12, tissues were treated with IL-1β (pro-inflammatory cytokine) and/or recombinant irisin.

• Biochemical assays measured glycosaminoglycan (GAG) content (a key cartilage matrix protein) and DNA content to assess chondrogenesis and cell viability.

Figure 2 - Study design. Articular chondrocytes were isolated from the carpometacarpalphalangeal joint from skeletally mature bovine donors and expanded for 3 days. Cells were then pelleted via centrifugation and differentited for 20 days using chondrogenic media, with treatment of pro-inflammatory cytokine IL-1β and/or recombinant irisin after Day 12.

Results

• Irisin alone: did not significantly affect GAG accumulation but increased DNA content, suggesting improved cell viability or proliferation.

• Irisin + IL-1β: significantly increased GAG production and GAG/DNA ratio compared to IL-1β treatment alone.

• These findings suggest irisin may help protect engineered cartilage from inflammatory damage and maintain tissue stability.

Figure 3 - Biochemical quantification of glycosaminoglycan (A) and DNA (B) content, as well as ratio of GAG/DNA (C), in engineered cartilage at Day 20 after treatment of pro-inflammatory cytokine IL-1β and myokine irisin as compared with controls. Data are presented as mean with standard deviation (n=4 independent samples). Statistical significance was determined via student t-test and assigned where appropriate with p < 0.05.

Conclusions

This pilot study highlights irisin’s potential role in promoting engineered cartilage stability in the presence of inflammation. By enhancing GAG production and possibly supporting cell viability, irisin may serve as a promising factor for cartilage tissue engineering and osteoarthritis therapies.

• Future directions include:

  • Gene and protein expression analysis of chondrogenic and degradation markers

  • Histological evaluation of matrix integrity

  • Deeper exploration of irisin’s role in cell survival and recovery mechanisms

Acknowledgements

• Research conducted under the supervision of Dr. Roshni Rainbow and the Regenerative Engineering Laboratory

• Supported by a 2022 NSERC USRA

References

[1] Arthritis Facts, Figures and Statistics. https://arthritis.ca/about-arthritis/what-is-arthritis/arthritis-facts-and-figures.

[2] Rainbow, R. S. et al. Osteoarthritis Cartilage 21, 990–998 (2013).

[3] Ning, K et al. Frontiers in Aging Neuroscience 14, 934406 (2022).