Artikel
Mimicking the early regenerative response of perivascular stem cells in vitro
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Veröffentlicht: | 23. Oktober 2017 |
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Gliederung
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Objectives: In vivo mesenchymal stem cells (MSCs) reside in the perivascular niche and are referred to as perivascular stem cells or pericytes. Isolation of CD45-CD34-CD146+ cells from different tissues has been shown to yield a highly proliferative and multipotent cell population. While these cells are well characterized in vitro, little is known about the regenerative potential of perivascular stem cells in vivo. Here, we aimed to simulate the microenvironment in the early stage of bone healing in vitro in order to study the regenerative response of perivascular stem cells.
Methods: Perivascular stem cells (CD34-CD146+) were enriched from human bone marrow mononuclear cells by MACS®. Different physiological and pathological microenvironments were simulated by using conditioned medium (CM) from cultures of primary human endothelial cells and osteoblasts (healthy bone), femoral head derived bone fragments (injured bone), and activated platelets (platelet-rich plasma (PRP), injury). Cells were incubated in the different media for 24h and analysed with respect to proliferation, gene expression, migration and osteogenic differentiation.
Results and Conclusion: Perivascular stem cells showed a specific response to different microenvironments. Cell proliferation, measured by DNA quantification, was observed in all media with highest values (2-fold increase) in PRP-CM and bone fragment-CM. All media induced chemokinetic activity of cells, while chemotactic attraction of cells was only observed for PRP-CM. A strong upregulation of Cox2 gene expression, a key component in immunomodulatory signalling was detected for PRP-CM and bone fragment-CM. Similarly, these microenvironments induced an upregulation of VEGF gene expression. The osteogenic differentiation potential of perivascular stem cells was retained for all media (Figure 1 [Fig. 1]).
Our results indicate that a microenvironment simulating bone injury elicits strong immunomodulatory and pro-angiogenic activity of perivascular stem cells. This suggests that in the early stage of bone healing the prime function of MSCs is in regulating the immune response and inducing neovascularization. Future studies will investigate the key components in CM driving this function, which might be potential targets to therapeutically stimulate the regenerative potential of perivascular stem cells.