During its tenure in vivo, synthetic mesh materials are exposed to foreign body responses, which can alter physicochemical properties of the material. Three different synthetic meshes comprised of polypropylene, expanded polytetrafluoroethylene (ePTFE), and polyethylene terephthalate (PET) materials were explanted from a single patient providing an opportunity to compare physicochemical changes between three different mesh materials in the same host. Results from infrared spectroscopy demonstrated significant oxidation in polypropylene mesh while ePTFE and PET showed slight chemical changes that may be caused by adherent scar tissue. Differential scanning calorimetry results showed a significant decrease in the heat of enthalpy and melt temperature in the polypropylene mesh while the ePTFE and PET showed little change. The presence of giant cells and plasma cells surrounding the ePTFE and PET were indicative of an active foreign body response. Scanning electron micrographs and photo micrographs displayed tissue entrapment and distortion of all three mesh materials.

Currently vascular repairs are treated using synthetic or biologic patches, however these patches have an array of complications, including calcification, rupture, re-stenosis, and intimal hyperplasia. An active patch material composed of decellulzarized tissue conjugated to gold nanoparticles (AuNPs) was developed and the long term biocompatibility and cellular integration was investigated. Porcine abdominal aortic tissue was decellularized and conjugated with 100nm gold nanoparticles (AuNP). These patches were placed over a longitudinal arteriotomy of the thoracic aorta in six pigs. The animals were monitored for six months. Gross, histological, and immunohistochemical analyses of the patches were performed after euthanasia. Grossly there was minimal scar tissue with the patches still visible on the outer surface of the vessel. The inner lumen was smooth with a seamless transition from patch to native tissue. Histology demonstrated infiltration of host cells into the patch material. The immunohistochemical results demonstrated an endothelial cell layer forming over the patch within the vessel. Smooth muscle cells were repopulating the biomaterial in all animals. These results demonstrated that the AuNP biomaterial patch integrated well with the host tissue and did not failed over the six month implantation time.

Vascular and cardiac reconstruction involves the use of biological patches to treat trauma and defects. An in vivo study was performed to determine the remodeling and biologic effects of novel nanostructured vascular patches with and without gold nanoparticles. Porcine vascular tissue was decellularized and conjugated with gold nanoparticles to evaluate if integration would occur while avoiding rupture and stenosis. Swine underwent a bilateral patch angioplasty of the carotid arteries with experimental patches on the right and control patches of bovine pericardium on the left. Animals were sacrificed after surgery and at 3 and 9 weeks. Ultrasound was performed during surgery, every 3 weeks, and before euthanasia. Endothelial regeneration was examined using Evans Blue dye and histology using Trichrome and H&E. There was a 100% success rate of implantation with 0% mortality. All patches were patent on ultrasound. At 3 weeks, experimental patches had regenerating endothelial cell growth and normal healing responses. At 9 weeks, the experimental patches demonstrated excellent integration. Histology demonstrated cellular in-growth into the experimental patches and no major immune reactions. This is one of the first studies to demonstrate the feasibility of nanomaterial-tissue patches for vascular and cardiac reconstruction.

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