Perivascular osteoprogenitors are associated with trans ‐cortical channels of long bones

We have identified a transcortical perivascular osteoprogenitor (TPC) located within cortical bone channels under basal conditions. When cortical bone was isolated from iDMP/T;ColGFP reporter mice and transplanted into recipient mice, TPCs migrate out of the bone into the newly forming bone marrow cavity where they continue to proliferate and differentiate to form new trabecular bone. AbstractBone remodeling and regeneration are dependent on resident stem/progenitor cells with the capability to replenish mature osteoblasts and repair the skeleton. Using lineage tracing approaches, we identified a population of Dmp1+ cells that reside within cortical bone and are distinct from osteocytes. Our aims were to characterize this stromal population of transcortical perivascular cells (TPCs) in their resident niche and evaluate their osteogenic potential. To distinguish this population from osteoblasts/osteocytes, we crossed mice containing inducible DMP1CreERT2/Ai9 tomato reporter (iDMP/T) with Col2.3GFP reporter (ColGFP), a marker of osteoblasts and osteocytes. We observed iDMP/T+;ColGFP ‐ TPCs within cortical bone following tamoxifen injection. These cells were perivascular and located within trans‐cortical channels.Ex vivo bone outgrowth cultures showed TPCs migrated out of the channels onto the plate and expressed stem cell markers such as Sca1, PDGFR β and leptin receptor. In a cortical bone transplantation model, TPCs migrate from their vascular niche within cortical bone,...
Source: Stem Cells - Category: Stem Cells Authors: Tags: Tissue ‐Specific Stem Cells Source Type: research