Single‑cell Transcriptomic Profiling of Bone Marrow Mesenchymal Stem Cells Reveals Lineage Heterogeneity and...

Osteoporosis (OP) and osteoarthritis (OA) are two skeletal disorders characterized by disrupted bone homeostasis. Transplantation of bone marrow mesenchymal stem cells (BM-MSCs) has emerged as a promising therapeutic strategy for both conditions; however, the precise molecular mechanisms mediating their beneficial effects remain poorly defined.

The GSE147287 dataset containing scRNA-seq data from BM-MSCs from OA and OP patients was obtained. Dimensionality reduction and cell clustering were performed using the Seurat R package, pseudotime trajectory analysis was carried out with the Monocle 2 package, and transcription factor (TF)-target gene regulatory networks were inferred using the GENIE3 R package. RT-qPCR quantified mRNA levels in a rat OP model, which was established via bilateral ovariectomy.

Nine distinct BM-MSC subtypes were classified. OP samples had higher osteocytes and neutrophils and lower macrophages, chondroblasts, monocytes, and plasma B cells than OA samples. Chondroblasts (4 clusters), 2/3 linked to autophagy, may drive OA-to-OP progression. Osteoblasts (the largest OP-OA difference) showed reduced osteoblast differentiation, downregulated Wnt pathway genes, and upregulated ossification genes in late stages. In the rat model, CAT, CHRDL1, RUNX1, ETS1, FOXO3, and TAL1 were dysregulated.

OP and OA exhibit distinct BM-MSC lineage heterogeneity. OA-to-OP progression involves enhanced oxidative phosphorylation and reduced autophagy. Downregulated RUNX1 (inhibiting NF-κB/IL-6) and Wnt pathway in OP were consistent with previous findings, showing the potential to serve as biomarkers for predicting disease progression and therapy response.

This study preliminarily examined BM-MSC lineage heterogeneity in OP and OA, clarifying the dynamic development, transcriptional regulation, and biological functions of chondrocytes and osteoblasts in these two bone diseases.