single cell RNA sequencing of intra- and extra- articular ligaments in mice

Knee ligaments, the anterior cruciate ligament (ACL) and medial collateral ligament (MCL), have unique functions but distinct regeneration capacities. However, the landscape of cellular heterogeneity in ligaments remains unclear. Here we profile the transcriptional signatures of ACL and MCL cells using single-cell RNA-sequencing. These ligaments consist of three fibroblast types that express Col22a1, Col12a1, or Col14a1 but have distinct localizations in the tissue. In addition, we find substantial heterogeneity in Col12a1 and Col14a1 positive cell clusters when comparing the ACL and MCL. Furthermore, we identified aging related changes in both cell composition and gene expression in ligaments. mRNA profiles of knee joint ligaments from 10 and 100 week-old mice