Bone fracture healing is a complex and dynamic process that involves a range of cellular interactions critical for successful tissue regeneration. Building on our previous single-cell RNA sequencing (scRNA-seq) studies that mapped the cellular components of mouse fracture callus, this study employs spatial transcriptomics to elucidate the precise locations and interactions of these cells in a mouse femur fracture model at day 0 before fracture and day 5, 15 post fracture. We utilized an optimized decalcification method using Morse's solution to significantly improve RNA quality, thereby enhancing the sequencing output from mouse femur fractures. We applied the Visium CytAssist platform followed by integrated analyses with the Seurat, CARD and Monocle frameworks. Our findings revealed the spatial localization of critical cell populations involved in bone healing, such as periosteum progenitor cells, and identify pivotal transcription factors that may regulate their differentiation into chondrocytes. Specifically, we applied deconvolution analysis to uncover how periosteum progenitor cells differentially recruit macrophages near the fracture line during early healing stages. Additionally, we utilized CellChat to explore potential receptor-ligand pathways that mediate these cellular interactions, further enhancing our understanding of the communication mechanisms essential for bone regeneration. This study advances our understanding of the cellular and molecular mechanisms underpinning fracture healing and highlights the potential of spatial transcriptomics as a powerful tool for identifying therapeutic targets.
