There is a significant clinical need for new approaches to treatment of mitral valve disease. The aim of this study was to develop a tissue-engineered mitral valve scaffold possessing appropriate composition and structure to ensure ideal characteristics of mitral valves, such as large orifice, rapid opening and closure, maintenance of mitral annulus–papillary muscle continuity, in vivo biocompatibility and extended durability. An extracellular matrix-based scaffold was generated, based on the native porcine mitral valve as starting material and a technique for porcine cell removal without causing damage to the matrix components. To stabilize these structures and slow down their degradation, acellular scaffolds were treated with penta-galloyl glucose (PGG), a well-characterized polyphenol with high affinity for collagen and elastin. Biaxial mechanical testing presented similar characteristics for the PGG-treated scaffolds compared to fresh tissues. The extracellular matrix components, crucial for maintaining the valve shape and function, were well preserved in leaflets, and in chordae, as shown by their resistance to collagenase and elastin. When extracted with strong detergents, the PGG-treated scaffolds released a reduced amount of soluble matrix peptides, compared to untreated scaffolds; this correlated with diminished activation of fibroblasts seeded on scaffolds treated with PGG. Cell-seeded scaffolds conditioned for 5 weeks in a valve bioreactor showed good cell viability. Finally, rat subdermal implantation studies showed that PGG-treated mitral valve scaffolds were biocompatible, nonimmunogenic, noninflammatory, and noncalcifying. In conclusion, a biocompatible mitral valve scaffold was developed, which preserved the biochemical composition and structural integrity of the valve, essential for its highly dynamic mechanical demands, and its biologic durability.

Diabetes is a major risk factor for the progression of vascular disease, contributing to elevated levels of glycoxidation, chronic inflammation and calcification. Tissue engineering emerges as a potential solution for the treatment of vascular diseases however there is a considerable gap in the understanding of how scaffolds and stem cells will perform in patients with diabetes. We hypothesized that adipose tissue-derived stem cells (ASCs) by virtue of their immunosuppressive potential would moderate the diabetes-intensified inflammatory reactions and induce positive construct remodeling. To test this hypothesis, we prepared arterial elastin scaffolds seeded with autologous ASCs and implanted them subdermally in diabetic rats and compared inflammatory markers, macrophage polarization, matrix remodeling, calcification and bone protein expression to control scaffolds implanted with and without cells in nondiabetic rats. ASC-seeded scaffolds exhibited lower levels of CD8+ T-cells and CD68+ pan-macrophages and higher numbers of M2 macrophages, smooth muscle cell-like and fibroblast-like cells. Calcification and osteogenic markers were reduced in ASCseeded scaffolds implanted in non-diabetic rats but remained unchanged in diabetes, unless the scaffolds were first pre-treated with penta-galloyl glucose (PGG), a known anti-oxidative elastin-binding polyphenol. In conclusion, autologous ASC seeding in elastin scaffolds is effective in combating diabetes-related complications. To prevent calcification, the oxidative milieu needs to be reduced by elastin-binding antioxidants such as PGG.

Pentagalloyl glucose (PGG) is currently being investigated as a non-surgical treatment for abdominal aortic aneurysms (AAAs); however, the molecular mechanisms of action of PGG on the AAA matrix components and the intra-luminal thrombus (ILT) still need to be better understood. To assess these interactions, we utilized peptide fingerprinting and molecular docking simulations to predict the binding of PGG to vascular proteins in normal and aneurysmal aorta, including matrix metalloproteinases (MMPs), cytokines, and fibrin. We performed PGG diffusion studies in pure fibrin gels and human ILT samples. PGG was predicted to bind with high affinity to most vascular proteins, the active sites of MMPs, and several cytokines known to be present in AAAs. Finally, despite potential binding to fibrin, PGG was shown to diffuse readily through thrombus at physiologic pressures. In conclusion, PGG can bind to all the normal and aneurysmal aorta protein components with high affinity, potentially protecting the tissue from degradation and exerting anti-inflammatory activities. Diffusion studies showed that thrombus presence in AAAs is not a barrier to endovascular treatment. Together, these results provide a deeper understanding of the clinical potential of PGG as a non-surgical treatment of AAAs.