Engineered Extracellular Vesicles From Human Periodontal-Ligament Stem Cells Increase VEGF/VEGFR2 Expression During Bone Regeneration.

Tiziana Orsini,Jacopo Pizzicannella,Agnese Gugliandolo,Placido Bramanti,Oriana Trubiani,Antonella Fontana,Francesca Diomede,Emanuela Mazzon,Alessia Ventrella

doi:10.3389/fphys.2019.00512

Abstract

Bone regeneration represents still a challenge, in particular for calvarium defects. Recently, the development of biomaterials with the addiction of stem cells is giving promising results for the treatment of bone defects. In particular, it was demonstrated that scaffolds enriched with mesenchymal stem cells (MSCs) and/or their derivatives, such as conditioned medium (CM) and extracellular vesicles (EVs), may improve bone regeneration. Moreover, given the deep link between osteogenesis and angiogenesis, a successful approach must also take into consideration the development of vascularization. In this work we evaluated the bone regeneration capacity of a collagen membrane (3D-COL) enriched with human periodontal-ligament stem cells (hPDLSCs) and CM or EVs or EVs engineered with polyethylenimine (PEI-EVs) in rats subjected to a calvarial defect. We evaluated also their capacity to induce angiogenic factors. At first, in vitro results showed an increased expression of osteogenic markers in hPDLSCs cultured with the 3D-COL and PEI-EVs, associated also with the increased protein levels of Vascular endothelial growth factor (VEGF) and VEGF receptor 2 (VEGFR2). The increased expression of these proteins was confirmed also in vivo in rats implanted with the 3D-COL enriched with hPDLSCs and PEI-EVs. Moreover, histological examination evidenced in this group of rats the activation of bone regeneration and of the vascularization process. Also MicroCT imaging with morphometric analysis confirmed in rats transplanted with 3D-COL enriched with hPDLSCs and PEI-EVs an important regenerative process and a better integration level. All together, these results evidenced that the 3D-COL enriched with hPDLSCs and PEI-EVs may promote bone regeneration of calvaria defects, associated also with an increased vascularization.

Highlights

Bone defects, that may be caused by trauma, malformations, tumor resection, have a great negative impact on the patients’ quality of life and bone regenerative medicine could be a promising approach for these patients (Dimitriou et al, 2011)
We evaluated the regeneration of calvaria in rats transplanted with a collagen membrane (3D-COL) enriched with mesenchymal stem cells (MSCs), namely human periodontal ligament stem cells, and/or their derivatives, such as conditioned medium (CM) and extracellular vesicles (EVs)
Given the important role played by Vascular endothelial growth factor (VEGF) in bone regeneration, we evaluated the capacity of human periodontal-ligament stem cells (hPDLSCs) and their derivatives to increase the protein levels of VEGF and its receptor VEGF receptor 2 (VEGFR2) in vitro

Summary

Introduction

That may be caused by trauma, malformations, tumor resection, have a great negative impact on the patients’ quality of life and bone regenerative medicine could be a promising approach for these patients (Dimitriou et al, 2011). Even if bone tissue has a great capacity to repair, in some conditions bone regeneration is needed in large quantity. Mesenchymal stem cells (MSCs) and their derivatives, such as conditioned medium (CM) and extracellular vesicles (EVs), in association with biomaterials have shown to be able to regenerate bone tissues, including calvaria defects (Diomede et al, 2018a,b,c,d). Bone regeneration is a process of great complexity, that is based on the interaction between various cell types. Blood vessels play a role as transporters of growth factors, minerals and others into the osteogenic microenvironment. They are needed as a structural template around which bone generation starts (Grosso et al, 2017)

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