Bone Disease and Regeneration: A Single-Cell Technique Termed Detects Vertebral Cellular Dynamics

Anshika Singh

Bone is a vital organ that performs a variety of functions, and the bone marrow within the skeleton consists of a complex mixture of hematopoietic, vascular, and spinal cells. Current single-cell RNA-sequencing (scRNA-seq) techniques reveal heterogeneity and broadly distinct hierarchical structures in spinal cells. Spinal stem and progenitor cells (SSPCs) are located upstream in the hierarchy and differentiate into chondrocytes, osteoblasts, osteocytes, and bone marrow adipocytes. In the bone marrow, several types of bone marrow stromal cells (BMSCs) with SSPC potential are localized in distinct spatial and temporal regions, and BMSCs may be replaced by SSPCs during aging. In vivo lineage tracing techniques show that different types of vertebral cells accumulate simultaneously and contribute to bone regeneration. In contrast, with aging these cells differentiate into adipocytes, causing senile osteoporosis. scRNA-seq analysis revealed that changes in celltype composition are the main cause of tissue senescence. In this review, we discuss the cellular dynamics of vertebral cell populations involved in bone homeostasis, regeneration, and osteoporosis.