Comparative analysis of gene expression identifies distinct molecular signatures of bone marrow- and periosteal-skeletal stem/progenitor cells

Abstract

Periosteum and bone marrow (BM) both contain skeletal stem/progenitor cells (SSCs) that participate in fracture repair. However, the functional difference and selective regulatory mechanisms of SSCs in different locations are unknown due to the lack of specific markers. Here, we report a comprehensive gene expression analysis of bone marrow SSCs (BM-SSCs), periosteal SSCs (P-SSCs), and more differentiated osteoprogenitors by using reporter mice expressing Interferon-inducible Mx1 and NestinGFP, previously known SSC markers. We first defined that the BM-SSCs can be enriched by the combination of Mx1 and NestinGFP expression, while endogenous P-SSCs can be isolated by positive selection of Mx1, CD105 and CD140a (known SSC markers) combined with the negative selection of CD45, CD31, and osteocalcinGFP (a mature osteoblast marker). Comparative gene expression analysis with FACS-sorted BM-SSCs, P-SSCs, Osterix+ preosteoblasts, CD51+ stroma cells and CD45+ hematopoietic cells as controls revealed that BM-SSCs and P-SSCs have high similarity with few potential differences without statistical significance. We also found that CD51+ cells are highly heterogeneous and have little overlap with SSCs. This was further supported by the microarray cluster analysis, where the two SSC populations clustered together but are separate from the CD51+ cells. However, when comparing SSC population to controls, we found several genes that are uniquely upregulated in endogenous SSCs. Amongst these genes, we found KDR (aka Flk1 or VEGFR2) to be most interesting and discovered that it is highly and selectively expressed in P-SSCs. This finding suggests that endogenous P-SSCs are functionally very similar to BM-SSCs with undetectable significant differences in gene expression but there are distinct molecular signatures in P-SSCs, which can be useful to specify P-SSC subset in vivo.

Hox gene expression determines cell fate of adult periosteal stem/progenitor cells

“…In particular, the periosteal stem/progenitor cell pool demonstrates greater self-renewal, more regenerative potential, and superior in vitro proliferative capacity 9 . This heightened interest has resulted in the identification of a unique surface marker profile describing the periosteal stem/progenitor cell 9 – 11 .…”

Bone regeneration strategies: Engineered scaffolds, bioactive molecules and stem cells current stage and future perspectives

“…Currently, in vivo studies in rodents are starting to confirm the existence of a structured hierarchy of skeletal progenitor cells [181, 182]. In terms of human stromal cells, in vitro expanded hPDSCs have been partly characterized at the single-cell level [165] and in whole genome studies [167], but additional work in terms of characterization of native hPDSCs and ASCs is required.…”

Treatment of intrabony defects with modified perforated membranes in aggressive periodontitis: subtraction radiography outcomes, prognostic variables, and patient morbidity

“…Consequently, the importance of periosteum and gingiva, as a notable source of mesenchymal stem cells (MSCs), which can efficiently contribute to the repair of bone defects, has been highlighted. Periosteum-derived stem/ progenitor cells (PDPCs) were found to express Leptin Receptor, Gremlin 1, and KDR (aka Flk1 or VEGFR2) [6]. Therefore, in course of injury or inflammation, PDPCs, controlled by periostin, would become activated to simultaneously trigger both angiogenic and bone repair processes of periodontal defects [7].…”