The gold standard material in bypass surgery of blood vessels remains the patient’s own artery or vein. However, this material may be unavailable, or may suffer vein graft disease. Currently available vascular prostheses, namely polyethylene terephthalate (PET, Dacron) and expanded polytetrafluoroethylene (ePTFE), perform well as large-caliber replacements, but their long-term patency is discouraging in small-caliber applications (<6 mm), such as in coronary, crural or microvessel surgery. This failure is mainly a result of an unfavorable healing process with surface thrombogenicity, due to lack of endothelial cells and anastomotic intimal hyperplasia caused by hemodynamic disturbances. An ideal small-diameter vascular graft has become a major focus of research. Novel biomaterials have been manufactured, and tissue-biomaterial interactions have been optimized. Tissue engineering technology has proven that the concept of partially or totally living blood vessels is feasible. The purpose of this review is to outline the vascular graft materials that are currently being implanted, taking into account cell-biomaterial physiology, tissue engineering approaches and the collective achievements of the authors.

Introduction: Uterus transplantation (UTx) is a rapidly evolving treatment of uterine-factor infertility. We report the results of the first 10 UTx procedures performed at our institution. Methods: The program started in April 2016 as a two-arm study comparing the efficacy of UTx from live donors (LD) and deceased donors (DD). Results: Between April 2016 and April 2018, we performed five DD UTx and five LD UTx. Two grafts had to be removed early due to thrombosis. One graft was removed due to chronic rejection and previous herpes simplex infection at month 7. Graft survival is 70% at one year. Recipient survival is 100% at two years. Live donor survival is 100% at three years. Three live-births have been achieved, two from a LD and one from a graft from a nulliparous DD. Vaginal anastomotic stenosis occurred in 63% (5/8) of grafts. Self-expanding stents have shown preliminary suitability for the treatment of vaginal stenosis. Three recipients developed severe acute rejection. Conclusion: The interim results of our study demonstrate mid-term viability in 70% of grafts. The LD UTx produced two live births and the DD UTx produced one live birth. Nulliparous donors should be considered for donation.

Background: Cardiovascular surgery is confronted by a lack of suitable materials for patch repair. Acellular animal tissues serve as an abundant source of promising biomaterials. The aim of our study was to explore the bio-integration of decellularized or recellularized pericardial matrices in vivo. Methods: Porcine (allograft) and ovine (heterograft, xenograft) pericardia were decellularized using 1% sodium dodecyl sulfate ((1) Allo-decel and (2) Xeno-decel). We used two cell types for pressure-stimulated recellularization in a bioreactor: autologous adipose tissue-derived stromal cells (ASCs) isolated from subcutaneous fat of pigs ((3) Allo-ASC and (4) Xeno-ASC) and allogeneic Wharton’s jelly mesenchymal stem cells (WJCs) ((5) Allo-WJC and (6) Xeno-WJC). These six experimental patches were implanted in porcine carotid arteries for one month. For comparison, we also implanted six types of control patches, namely, arterial or venous autografts, expanded polytetrafluoroethylene (ePTFE Propaten^® Gore^®), polyethylene terephthalate (PET Vascutek^®), chemically stabilized bovine pericardium (XenoSure^®), and detoxified porcine pericardium (BioIntegral^® NoReact^®). The grafts were evaluated through the use of flowmetry, angiography, and histological examination. Results: All grafts were well-integrated and patent with no signs of thrombosis, stenosis, or aneurysm. A histological analysis revealed that the arterial autograft resembled a native artery. All other control and experimental patches developed neo-adventitial inflammation (NAI) and neo-intimal hyperplasia (NIH), and the endothelial lining was present. NAI and NIH were most prominent on XenoSure^® and Xeno-decel and least prominent on NoReact^®. In xenografts, the degree of NIH developed in the following order: Xeno-decel > Xeno-ASC > Xeno-WJC. NAI and patch resorption increased in Allo-ASC and Xeno-ASC and decreased in Allo-WJC and Xeno-WJC. Conclusions: In our setting, pre-implant seeding with ASC or WJC had a modest impact on vascular patch remodeling. However, ASC increased the neo-adventitial inflammatory reaction and patch resorption, suggesting accelerated remodeling. WJC mitigated this response, as well as neo-intimal hyperplasia on xenografts, suggesting immunomodulatory properties.