Elsevier

Bone Reports

Volume 15, December 2021, 101109
Bone Reports

Development and validation of a new method to isolate, expand, and differentiate circulating osteogenic precursor (COP) cells

https://doi.org/10.1016/j.bonr.2021.101109Get rights and content
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Highlights

  • COP cells are progenitor cells in the peripheral blood with the capacity to form bone in vitro and in vivo.

  • A lack of COP culture models and inconsistent characterization has limited mechanistic research.

  • We developed and validated a new method to isolate, expand, and differentiate COP cells.

Abstract

Circulating osteogenic precursor (COP) cells are a population of progenitor cells in the peripheral blood with the capacity to form bone in vitro and in vivo. They have characteristics of the mesenchymal stem and progenitor pool found in the bone marrow; however, more recently, a population of COP cells has been identified with markers of the hematopoietic lineage such as CD45 and CD34. While this population has been associated with several bone pathologies, a lack of cell culture models and inconsistent characterization has limited mechanistic research into their behavior and physiology. In this study, we describe a method for the isolation of CD45+/CD34+/alkaline phosphatase (ALP) + COP cells via fluorescence-activated cell sorting, as well as their expansion and differentiation in culture. Hematopoietic COP cells are a discreet population within the monocyte fraction of the peripheral blood mononuclear cells, which form proliferative, fibroblastoid colonies in culture. Their expression of hematopoietic markers decreases with time in culture, but they express markers of osteogenesis and deposit calcium with differentiation. It is hoped that this will provide a standard for their isolation, for consistency in future research efforts, to allow for the translation of COP cells into clinical settings.

Keywords

Circulating osteogenic precursor cells
Stem cells
Peripheral blood stem cells
Hematopoietic stem cells
Mesenchymal stem cells
Osteoprogenitors

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