Mesenchymal Stem Cells Enhance Angiogenesis in Mechanically Viable Prevascularized Tissues via Early Matrix Metalloproteinase Upregulation

Abstract

Angiogenesis, the sprouting of new blood vessels from existing vasculature, is a complex biological process of interest to both the treatment of numerous pathologies and the creation of thick engineered tissues. In the context of tissue engineering, one potential solution to the diffusion limitation is to create a vascular network in vitro that can subsequently anastomose with the host after implantation, allowing the implantation of thicker, more complex tissues. In this study, the ability of endothelial cells to sprout and form stable vascular networks in 3-dimensional (3D) fibrin matrices was investigated as a function of matrix density in a prevascularized tissue model. The results demonstrate that while increasing matrix density leads to a nearly 7-fold increase in compressive stiffness, vascular sprouting is virtually eliminated in the most dense matrix condition. However, the addition of human mesenchymal stem cells (HMSCs) to the denser matrices reverses this effect, resulting in an up to a 7-fold increase in network formation. Although the matrix metalloproteinases (MMPs) MMP-2, MMP-9, and MT1-MMP are all upregulated early on with the addition of HMSCs, MT1-MMP appears to play a particularly important role in the observed angiogenic response among these proteases. This study provides a means to design stiffer prevascularized tissues utilizing naturally derived substrates, and its results may yield new mechanistic insights into stem cell-based angiogenic therapies.

Visualization of Polarized Membrane Type 1 Matrix Metalloproteinase Activity in Live Cells by Fluorescence Resonance Energy Transfer Imaging

“…Interestingly, recent studies have demonstrated that cell adhesion, cytoskeletal organization, and mobility are distinct within the confines of the threedimensional extracellular matrix versus two-dimensional environment (53,54). As such, the new techniques described herein should prove useful for eventually extending these analyses into the more complex third dimension (55,56).…”

Generation of Multi-scale Vascular Network System Within 3D Hydrogel Using 3D Bio-printing Technology

“…Endothelial-coated surface and extracellular matrix (ECM) proteins played a critical role in this early development of EC sprouting 6,13,15 . However, signals from growth factors or mural cells are necessary to maintain and promote the EC sprouting 14,17,38,39 . In our proposed vascular tissue model with capillary network, large number of NHLFs secret signaling molecules ( e.g.…”

Biomaterials to Prevascularize Engineered Tissues

“…Increasing the fibrinogen concentration reduces the porosity, while increasing the density and stiffness of the fibrin matrix. Although increasing the matrix density increases the number of cell-matrix binding sites, the decrease of porosity and enhanced stiffness are dominant leading to reduced angiogenesis [61].…”