Collagen-based barrier membranes are an essential component in Guided Bone Regeneration (GBR) procedures. They act as cell-occlusive devices that should maintain a micromilieu where bone tissue can grow, which in turn provides a stable bed for prosthetic implantation. However, the standing time of collagen membranes has been a challenging area, as native membranes are often prematurely resorbed. Therefore, consolidation techniques, such as chemical cross-linking, have been used to enhance the structural integrity of the membranes, and by consequence, their standing time. However, these techniques have cytotoxic tendencies and can cause exaggerated inflammation and in turn, premature resorption, and material failures. However, tissues from different extraction sites and animals are variably cross-linked. For the present in vivo study, a new collagen membrane based on bovine dermis was extracted and compared to a commercially available porcine-sourced collagen membrane extracted from the pericardium. The membranes were implanted in Wistar rats for up to 60 days. The analyses included well-established histopathological and histomorphometrical methods, including histochemical and immunohistochemical staining procedures, to detect M1- and M2-macrophages as well as blood vessels. Initially, the results showed that both membranes remained intact up to day 30, while the bovine membrane was fragmented at day 60 with granulation tissue infiltrating the implantation beds. In contrast, the porcine membrane remained stable without signs of material-dependent inflammatory processes. Therefore, the bovine membrane showed a special integration pattern as the fragments were found to be overlapping, providing secondary porosity in combination with a transmembraneous vascularization. Altogether, the bovine membrane showed comparable results to the porcine control group in terms of biocompatibility and standing time. Moreover, blood vessels were found within the bovine membranes, which can potentially serve as an additional functionality of barrier membranes that conventional barrier membranes do not provide.

(1) Background: The aim of the present study was the biocompatibility analysis of a novel xenogeneic vascular graft material (PAP) based on native collagen won from porcine aorta using the subcutaneous implantation model up to 120 days post implantationem. As a control, an already commercially available collagen-based vessel graft (XenoSure®) based on bovine pericardium was used. Another focus was to analyze the (ultra-) structure and the purification effort. (2) Methods: Established methodologies such as the histological material analysis and the conduct of the subcutaneous implantation model in Wistar rats were applied. Moreover, established methods combining histological, immunohistochemical, and histomorphometrical procedures were applied to analyze the tissue reactions to the vessel graft materials, including the induction of pro- and anti-inflammatory macrophages to test the immune response. (3) Results: The results showed that the PAP implants induced a special cellular infiltration and host tissue integration based on its three different parts based on the different layers of the donor tissue. Thereby, these material parts induced a vascularization pattern that branches to all parts of the graft and altogether a balanced immune tissue reaction in contrast to the control material. (4) Conclusions: PAP implants seemed to be advantageous in many aspects: (i) cellular infiltration and host tissue integration, (ii) vascularization pattern that branches to all parts of the graft, and (iii) balanced immune tissue reaction that can result in less scar tissue and enhanced integrative healing patterns. Moreover, the unique trans-implant vascularization can provide unprecedented anti-infection properties that can avoid material-related bacterial infections.

Background/Aim: Cardiovascular diseases are one of the most common causes of morbidity and mortality in the world. In the case of severe arteriosclerotic damage, surgical treatment is necessary. Although the use of autologous vessels is still considered to be the gold standard, sufficient autologous vessels for transplantation are lacking. Materials and Methods: In the present study, histological examination and in vitro cytotoxicity analysis according to DIN EN ISO 10993-5 were performed on a newly developed porcine vascular graft from a decellularized aorta. A conventional bovine graft was used as control. Results: The ex vivohistological analysis revealed the effectiveness of a new purification process on the microstructure and the removal of xenogeneic antigen-bearing structures in the new vessels. Furthermore, cell viability and cytotoxicity assays revealed full cytocompatibility. Conclusion: The novel graft shows no structural damage and gets completely decellularized by the purification process. Superior cytocompatibility, compared with the bovine-derived vascular graft, was demonstrated.Cardiovascular diseases like cerebral, coronary and peripheral artery diseases are one of the most frequent causes of morbidity and mortality, especially in industrialized nations (1, 2). The luminal narrowing of the vessels and the resulting insufficient supply of the downstream organs and tissues with oxygen and nutrients, as well as the potential complete vascular occlusion or spontaneous vascular rupture, are preceded by frequent arteriosclerotic changes in the vessels (3,4). The presence of a manifest cardiovascular disease can dramatically increase, e.g., both the risk of the emergence of a heart attack and a stroke (5). Depending on the exact location and extent of the occlusion, various therapy options are possible. In addition to conventional drug therapy, various surgical methods are common, especially for high-grade occlusions. This includes percutaneous transluminal angioplasty (PTA) or, for the coronary vessels, percutaneous coronary intervention (PCI), as well as thrombo-endarterectomy (TAE) with and without additional repair patch, but also direct vascular replacement by inserting an interposal or bypass surgery (6, 7).Restoring blood flow through the installation of a bypass system is often the preferred method, particularly in the case of long occlusions. There are various options available to the surgeon when choosing the bypass material. In addition to autologous transplants from the patient´s own vessels, this also includes homografts, processed xenografts, completely synthetic and biohybrid grafts. Autologous grafts are still considered the gold standard for interventional vascular replacement today, as they allow for the best clinical outcomes (8, 9). Depending on the location of the vascular stenosis, age, general health and comorbidities of the patient, different vessels can be used. In addition to the great saphenous vein and the saphenous vein, the internal thoracic artery as well as the ulnar art...