Comparative assessment of chondral defect repair using human bone marrow- and adipose tissue-derived mesenchymal stem cells, adult and foetal articular cartilage-derived chondrocytes, and chondroprogenitors: an ex-vivo model

Abstract

Purpose: Cartilage repair necessitates adjunct therapies such as cell-based approaches, which commonly use MSCs and chondrocytes but is limited by the formation of fibro-hyaline cartilage. Articular cartilage-derived chondroprogenitors(CPs) offer promise in overcoming this, as they exhibit higher chondrogenic and lower hypertrophic phenotypes. The study aimed to compare the efficacy of various cell types derived from adult and foetal cartilage suspended in platelet-rich plasma(PRP) in repairing chondral defects in an Ex-vivo Osteochondral Unit(OCU) model.

Methods: In-vitro characterization of the cells included growth kinetics, FACS, qRT-PCR, and multilineage differentiation potential using histology and GAG analysis. Ex-vivo human OCUs with chondral defects containing the different cells in PRP were cultured and subjected to analysis for matrix and collagen staining.

Results: The ex-vivo OCU analysis, in terms of defect repair, showed that adult chondrocytes, sorted-CPs, and foetal MCPs displayed better host integration and filling. The In-vitro analysis of adult chondrocytes displayed greater chondrogenic genes ACAN and COL2A1 expression, with sorted-CPs also showing higher levels of ACAN. In terms of accumulation of extracellular matrix uptake evident by Safranin O staining and collagen type II fibrillar uptake, the AD-MSCs, BM-MSCs, and sorted CPs outperformed the other groups. BM-MSCs also showed corroborative higher CD146 levels, however, the gene analysis of the AD-MSCs showed a high hypertrophic tendency in terms of its COL1A1 and RUNX2 expression.

Conclusion: Sorted chondroprogenitors outperformed both in terms of filling and hyaline-like repair, with AD-MSC and BM-MSC groups also achieving functional cartilage of a hyaline nature, warranting further evaluation using in-vivo and clinical studies.

Keywords: Chondrocytes; Chondroprogenitors; Ex-vivo osteochondral units; Hyaline repair; Mesenchymal stem cells; Platelet rich plasma.