Repairing the structure and functionality associated with subcutaneous cartilage defects continues to be a challenge in the fields of plastic and reconstructive surgery. While current methods, including autologous chondrocyte implantation and matrix-assisted chondrocyte implantation, have been successful in some regard, they continue to present a number of limitations, including donor limitation, donor morbidity, and degradation of the graft tissue.
Recently, cartilage progenitor cell (CPC)-based tissue engineering has drawn attention in the field of cartilage regeneration, primarily for its strong chondrogenic differentiation capacity.
Unfortunately, a general lack of a suitable chondrogenic niche has continued to hinder the clinical application of CPC-regenerated cartilage in the subcutaneous environment.
Considering this, and for the purposes of this study, Chen et al. explored the use of exosomes derived from chondrocytes (CC-Exos) as a way to provide the CPC constructs with a cartilage signal in subcutaneous environment for efficient ectopic cartilage regeneration.
After 12 weeks of post-surgical injection of CC-Exos, the authors’ animal model demonstrated that the CC-Exos injections effectively increased collagen deposition and minimized vascular ingrowth in engineered constructs, which efficiently and reproducibly developed into cartilage. This study also demonstrated that the CPC constructs supplied with these CC-Exos could also form cartilage-like tissue with minimal hypertrophy in a subcutaneous environment and with no help from any chondrogenic factors.
Additionally, Chen et al.’s study showed that CC-Exos significantly promoted chondrogenesis-related factors at the mRNA and protein levels in CPCs while also limiting angiogenesis typically associated with hypertrophic differentiation and subsequent calcification.
Despite these promising results, Chen et al. point out that the exact components associated with CC-Exos have yet to be determined. Because of this, the authors call for additional studies to determine the specific components of CC-Exos and their underlying mechanisms related to cartilage repair.
Considering the findings of this study, the authors believe that CC-Exos alone could provide a preferable chondrogenic environment, help maintain the stability of cartilage tissue, and serve as a promising therapeutic approach for the treatment of ectopic cartilage defects.
Source: Chen, Y., Xue, K., Zhang, X. et al. Exosomes derived from mature chondrocytes facilitate subcutaneous stable ectopic chondrogenesis of cartilage progenitor cells. Stem Cell Res Ther 9, 318 (2018). https://doi.org/10.1186/s13287-018-1047-2
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