Specific recruitment of circulating angiogenic cells using biomaterials as filters

Endothelium-dependent remote signaling in ischemia and reperfusion: Alterations in the cardiometabolic continuum

Intact endothelial function plays a fundamental role for the maintenance of cardiovascular (CV) health. The endothelium is also involved in remote signaling pathway-mediated protection against ischemia/reperfusion (I/R) injury. However, the transfer of these protective signals into clinical practice has been hampered by the complex metabolic alterations frequently observed in the cardiometabolic continuum, which affect redox balance and inflammatory pathways. Despite recent advances in determining the distinct roles of hyperglycemia, insulin resistance (InR), hyperinsulinemia, and ultimately diabetes mellitus (DM), which define the cardiometabolic continuum, our understanding of how these conditions modulate endothelial signaling remains challenging. It is widely accepted that endothelial cells (ECs) undergo functional changes within the cardiometabolic continuum. Beyond vascular tone and platelet-endothelium interaction, endothelial dysfunction may have profound negative effects on outcome during I/R. In this review, we summarize the current knowledge of the influence of hyperglycemia, InR, hyperinsulinemia, and DM on endothelial function and redox balance, their influence on remote protective signaling pathways, and their impact on potential therapeutic strategies to optimize protective heterocellular signaling.

Bioengineering strategies for the treatment of peripheral arterial disease

Peripheral arterial disease (PAD) is a progressive atherosclerotic disorder characterized by narrowing and occlusion of arteries supplying the lower extremities. Approximately 200 million people worldwide are affected by PAD. The current standard of operative care is open or endovascular revascularization in which blood flow restoration is the goal. However, many patients are not appropriate candidates for these treatments and are subject to continuous ischemia of their lower limbs. Current research in the therapy of PAD involves developing modalities that induce angiogenesis, but the results of simple cell transplantation or growth factor delivery have been found to be relatively poor mainly due to difficulties in stem cell retention and survival and rapid diffusion and enzymolysis of growth factors following injection of these agents in the affected tissues. Biomaterials, including hydrogels, have the capability to protect stem cells during injection and to support cell survival. Hydrogels can also provide a sustained release of growth factors at the injection site. This review will focus on biomaterial systems currently being investigated as carriers for cell and growth factor delivery, and will also discuss biomaterials as a potential stand-alone method for the treatment of PAD. Finally, the challenges of development and use of biomaterials systems for PAD treatment will be reviewed.

Modifying decellularized aortic valve scaffolds with stromal cell-derived factor-1α loaded proteolytically degradable hydrogel for recellularization and remodeling

Decellularized matrix is of great interest as a scaffold for the tissue engineering heart valves due to its naturally three-dimensional structure and bioactive composition. A primary challenge of tissue engineered heart valves based on decellularized matrix is to grow a physiologically appropriate cell population within the leaflet tissue. In this study, a composite scaffold was fabricated by the combination of a porous matrix metalloproteinase (MMP) degradable poly (ethylene glycol) (PEG) hydrogel that were loaded with stromal cell-derived factor-1α (SDF-1α) and a mechanically supportive decellularized porcine aortic valve. Results demonstrated that the modified scaffold enhanced bone marrow mesenchymal stem cells (BMSC) adhesion, viability and proliferation, and promoted BMSC differentiate into valve interstitial-like cells. Furthermore, these modifications lead to enhanced protection of the scaffold from thrombosis. In vivo assessment by rat subdermal model showed the modified scaffold was highly biocompatible with tissue remodeling characterized by promoting mesenchymal stem cells recruitment and facilitating M2 macrophage phenotype polarization. The surface layers of PEG hydrogel not only could provide a niche for cell migration, proliferation and differentiation, but also protect the scaffolds from rapid degeneration, inflammation and calcification. The intermediate layer of decellularized valve could maintain the organization of the scaffold and perform the valve function. The promising results emphasize the potential of our scaffolds to improve recellularization and promote remodeling of implanted decellularized valves. These findings suggest that the SDF-1α loaded MMP degradable PEG hydrogel modification could be an efficient approach to develop functional decellularized heart valve. STATEMENT OF SIGNIFICANCE: A composite scaffold was fabricated by the combination of a porous matrix metalloproteinase (MMP) degradable poly (ethylene glycol) (PEG) hydrogel that were loaded with SDF-1α and a mechanically supportive decellularized porcine aortic valve. The surface layers of PEG hydrogel not only could provide a niche for cell migration, proliferation and differentiation, but also protect the scaffolds from rapid degeneration, inflammation and calcification. The intermediate layer of decellularized valve could maintain the organization of the scaffold and perform the valve function. The promising results emphasize the ability of our scaffolds to improve recellularization and promote remodeling of implanted decellularized valves. This suggests that the extracellular matrix-based valve scaffolds have potential for clinical applications.