Intra-articular injection of IMRCs repairs punch defects in the rabbits’ meniscus
fibrous
The efficacy of this IMRCs-based therapy was further evaluated. At week 8 post-injection, samples of the entire meniscus of rabbits were collected for macroscopic observations and assessed using a semi-quantitative scale according to the previous report.Strongly positive Safranin-O staining (red) of extracellular matrix and glycosaminoglycan content was observed in the regenerated tissues in the IMRCs group at week 8, similar to the natural meniscus tissue (Supplementary Fig. Masson trichrome-stained sections were used to assess collagen distribution, orientation, and characterization of the matrix components. In a normal meniscus, a large number of collagen fibers were arranged in parallel. Meanwhile, chondrocytes, including some clusters of chondrocytes, were usually located in rows between fibrous bundles (Supplementary Fig. The histochemical staining of type I collagen (Col-1) and type II collagen (Col-2) fibers showed that Col-1 was lower in and around the repair foci, but Col-2 of repair foci was observed in the IMRCs group (Fig. We further performed semi-quantitative histological scoring of the regenerated meniscus tissue using a modified Pauli scoring system,