A Single-Cell Transcriptomic Atlas Characterizes Age-Related Changes of Murine Cranial Stem Cell Niches

The bone tissue undergoes constant turnover, which relies on skeletal stem cells (SSCs) and/or mesenchymal stem cells (MSCs) and their niches. SSCs/MSCs and their perivascular niche within the bone marrow are well characterized in long bones. As for cranial bones, besides bone marrow, the suture mesenchyme has been identified as a unique niche for SSCs/MSCs of craniofacial bones. However, a comprehensive study of the two different cranial stem cell niches at single-cell resolution is still lacking. In addition, during the progression of aging, age-associated changes in cranial stem cell niches and resident cells remain uncovered. In this study, we investigated age-related changes in cranial stem cell niches via single-cell RNA sequencing (scRNA-seq). Mouse cranial bone marrow tissue was harvested from wild-type C57BL/6 mice of three different age groups, i.e., two months old (02m), twelve months old (12m), and eighteen months old (18m), with six to eight male mice (6M-8M) in each group. In total, six libraries were created, including three libraries of cranial bone marrow adjacent to the suture (CBMA_02m; CBMA_12m; CBMA_18m) and three libraries of cranial bone marrow distant from the suture (CBMD_02m; CBMD_12m; CBMD_18m).