Type II collagen-positive progenitors are important stem cells in controlling skeletal development and vascular formation

Type II collagen-positive progenitors are important stem cells in controlling skeletal development and vascular formation

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Abstract Type II collagen-positive (Col2+) cells have been reported as skeletal stem cells (SSCs), but the contribution of Col2+ progenitors to skeletal development both prenatally and postnatally during aging remains unclear.To address this question, we generated new mouse models with ablation of Col2+ cells at either the embryonic or postnatal stages.The embryonic ablation of Col2+ progenitors resulted in the death of newborn mice due to a decrease in skeletal blood vessels, loss of all vertebral bones and absence of most other bones except part of the craniofacial bone, the clavicle bone and a small piece of the long bone and ribs, which suggested that intramembranous ossification is involved in long bone development but does not participate in spine development.The postnatal ablation of Col2+ cells mr robot funko resulted in mouse growth retardation and a collagenopathy phenotype.Lineage tracing experiments with embryonic or postnatal mice revealed that Col2+ progenitors occurred predominantly in the growth plate (GP) and articular cartilage, but a limited number of Col2+ cells were detected in the bone marrow.

Moreover, the number and differentiation ability of Col2+ progenitors in the long bone and knee joints decreased with increasing age.The fate-mapping study further revealed Col2+ lineage cells contributed to, in addition to osteoblasts and chondrocytes, CD31+ blood vessels in both the calvarial bone and long bone.Specifically, almost all blood vessels in calvarial bone and 25.4% of blood vessels in long bone were Col2+ lineage cells.However, during fracture healing, 95.

5% of CD31+ blood vessels in long bone were Col2+ lineage cells.In vitro studies grand love red heart reposado tequila further confirmed that Col2+ progenitors from calvarial bone and GP could form CD31+ vascular lumens.Thus, this study provides the first demonstration that intramembranous ossification is involved in long bone and rib development but not spine development.Col2+ progenitors contribute to CD31+ skeletal blood vessel formation, but the percentage differs between long bone and skull bone.The number and differentiation ability of Col2+ progenitors decreases with increasing age.