Dissecting human embryonic skeletal stem cell ontogeny by single-cell transcriptomic and functional analyses

Abstract

Human skeletal stem cells (SSCs) have been discovered in fetal and adult long bones. However, the spatiotemporal ontogeny of human embryonic SSCs during early skeletogenesis remains elusive. Here we map the transcriptional landscape of human limb buds and embryonic long bones at single-cell resolution to address this fundamental question. We found remarkable heterogeneity within human limb bud mesenchyme and epithelium, and aligned them along the proximal–distal and anterior–posterior axes using known marker genes. Osteo-chondrogenic progenitors first appeared in the core limb bud mesenchyme, which give rise to multiple populations of stem/progenitor cells in embryonic long bones undergoing endochondral ossification. Importantly, a perichondrial embryonic skeletal stem/progenitor cell (eSSPC) subset was identified, which could self-renew and generate the osteochondral lineage cells, but not adipocytes or hematopoietic stroma. eSSPCs are marked by the adhesion molecule CADM1 and highly enriched with FOXP1/2 transcriptional network. Interestingly, neural crest-derived cells with similar phenotypic markers and transcriptional networks were also found in the sagittal suture of human embryonic calvaria. Taken together, this study revealed the cellular heterogeneity and lineage hierarchy during human embryonic skeletogenesis, and identified distinct skeletal stem/progenitor cells that orchestrate endochondral and intramembranous ossification.

Ferulic Acid Promotes Bone Defect Repair After Radiation by Maintaining the Stemness of Skeletal Stem Cells

“…reported. 18,24,27,28 As shown in Figure 1A Figure 1G) (**P < .01, ***P < .001). Moreover, irradiation inhibited ALP activity and osteogenic mineralization ( Figure 1H) and the expression of osteogenic genes, including Runx-2 and OPN ( Figure 1I), in SSCs.…”

“…Nevertheless, we must acknowledge that there are several limitations in our study. First, although CD105 and CD140a have been identified as of the stemness markers of mesenchyma-derived stem cells in the previous reports, 17,18,24,27,28 we are aware that more cell surface markers maybe useful for the evaluation of the response of SSC to irradiation and high-throughput works may be needed in future studies. Second, although we have identified that MAPK pathways mainly contribute to the regulatory effects of FA on SSC, the potential role of other pathways, such as the TGF-β/SMAD and NF-κB pathways, should be investigated in future studies.…”

“…SSCs were isolated from long bones according to our previously reported procedure with minor revisions. 24,26 Briefly, femurs and tibiae from C57BL/6 mice were dissected, and the bone marrow cells were flushed out before the long bones were chopped and digested by collagenase II (Sigma U.S., 0.1% vol/vol) at 37 C for 1 hour. The released cells were discarded, and the digested bone chips were cultured in minimum essential medium eagle, alpha modification (α-MEM; Invitrogen, Carlsbad, California, U.S.) supplemented with 10% fetal bovine serum (FBS) (HyClone, Logan, Utah, U.S.).…”

Clinical-grade hDPSCs&nbsp;Suppressed the Activation of Osteoarthritic Macrophages and Attenuated Cartilaginous Damage in a Rabbit OA&nbsp;Model

“…To understand the molecular mechanism underlying the suppressive effect of hDPSCs on osteoarthritic macrophages, the MAPK pathway was chosen for investigation, as it was reported to be involved in macrophage activation in in ammatory microenvironments [29,[38][39][40]. OASF induced marked activation of the p38/MAPK, ERK/MAPK, and JNK/SAPK pathways in osteoarthritic macrophages.…”

“…In recent decades, we have been pursuing preclinical research and clinical applications of stem cell-based therapy for the treatment of severe diseases [19][20][21][22][23][24][25][26][27][28][29]. Notably, we explored the therapeutic effects of hDPSCs on several skeletal disorders, including rheumatoid arthritis, osteoporosis, and tooth loss [30][31][32].…”