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Objective: Tissue integration of vascular grafts partially depends on the host response to injury, which immediately begins after implantation and restoration of the circulation. In an infected environment, the inflammation changes the incorporation patterns. The aim of the study was to observe the tissue incorporation process, in a normal and an infected environment. Methods: We have created an experimental model by performing subfascial implantation of four types of vascular grafts, in rats (woven Dacron®, knitted Dacron®, silver coated Dacron® and expanded Polytetrafloroethylene -ePTFE) and by infecting some of them with three different bacterial strains. We have retrieved the noninfected grafts at two and four weeks after implantation, whilst the infected ones at one, two and three weeks. Results: Detailed microscopic appearences were analysed. The control and infected groups were compared. Statistical significance was calculated for various corelations. Conclusions: The morphopathological findings showed that the ePTFE graft's structure was best preserved. Statistical significance existed between the bacterial strain and the degree of inflammation. The silver coated Dacron® was not shown to be superior to the knitted Dacron®. The poorest incorporation was the one of the woven Dacron®.

Currently, microfracturing is the most commonly used cartilage repair procedure in cartilage defects. Our aim was to study the mechanism of in vivo cartilage repair in case of full-thickness articular cartilage damage of the knee using a three-dimensional matrix implanted without any preseeded cells in the defect. We also investigated whether platelet-rich plasma application after microfracture procedure of the knee is associated with improved outcome compared with traditional microfracture treatment alone in a rabbit model. Histological examination of the chondral defects, revealed the largest amount of new tissue with hyaline-like cartilage features in Hyalofast group. At 12 weeks from implantation of the Hyalofast scaffold demonstrated complete filling of the defect with hyaline cartilage in admixture with the scaffold and bone metaplasia in the deepest areas. In the PRP group, complete filling of the defect with an admixture of fibrous and hyaline-like cartilage tissue appeared with a discreet tendency of endochondral ossification. We confirmed the superiority of the autologous matrix-induced chondrogenesis compared to microfracture and PRP or microfracture alone in case of full-thickness articular cartilage damage of the knee.

Introduction: Pediatric patients with cardiac congenital diseases require heart valve implants that can grow with their natural somatic increase in size. Current artificial valves perform poorly in children and cannot grow; thus, living-tissue-engineered valves capable of sustaining matrix homeostasis could overcome the current drawbacks of artificial prostheses and minimize the need for repeat surgeries.Materials and Methods: To prepare living-tissue-engineered valves, we produced completely acellular ovine pulmonary valves by perfusion. We then collected autologous adipose tissue, isolated stem cells, and differentiated them into fibroblasts and separately into endothelial cells. We seeded the fibroblasts in the cusp interstitium and onto the root adventitia and the endothelial cells inside the lumen, conditioned the living valves in dedicated pulmonary heart valve bioreactors, and pursued orthotopic implantation of autologous cell-seeded valves with 6 months follow-up. Unseeded valves served as controls.Results: Perfusion decellularization yielded acellular pulmonary valves that were stable, no degradable in vivo, cell friendly and biocompatible, had excellent hemodynamics, were not immunogenic or inflammatory, non thrombogenic, did not calcify in juvenile sheep, and served as substrates for cell repopulation. Autologous adipose-derived stem cells were easy to isolate and differentiate into fibroblasts and endothelial-like cells. Cell-seeded valves exhibited preserved viability after progressive bioreactor conditioning and functioned well in vivo for 6 months. At explantation, the implants and anastomoses were intact, and the valve root was well integrated into host tissues; valve leaflets were unchanged in size, non fibrotic, supple, and functional. Numerous cells positive for a-smooth muscle cell actin were found mostly in the sinus, base, and the fibrosa of the leaflets, and most surfaces were covered by endothelial cells, indicating a strong potential for repopulation of the scaffold.Conclusions: Tissue-engineered living valves can be generated in vitro using the approach described here. The technology is not trivial and can provide numerous challenges and opportunities, which are discussed in detail in this paper. Overall, we concluded that cell seeding did not negatively affect tissue-engineered heart valve (TEHV) performance as they exhibited as good hemodynamic performance as acellular valves in this model. Further understanding of cell fate after implantation and the timeline of repopulation of acellular scaffolds will help us evaluate the translational potential of this technology.

Introduction: Local Anesthetic Systemic Toxicity (LAST) is the most feared local anesthesia accident. As the cardiac arrest determined by LAST is mostly refractory to known resuscitation protocols, due local anesthetic blockade produced in the cardiac cells, the Lipid Emulsion (L.E) has been proved to be beneficial in resuscitating the cardiac arrest determined by local anesthetic. The aim for this presentation is to ease future studies on this topic, to ensure a starting point for next related research on LAST and LE mechanism of action. Method: Under genaral anesthesia we induced Local Anesthetic Systemic Toxicity to a rat model, by injecting Ropivacaine into the inferior vena cava. We monitored the cardiac activity of the subjects during the experiment. We used 4 groups of rats, control group- no intervention, lipid group- lipid emulsion was adminsitered, local anesthetic group- local anesthetic was administered and local anesthetic and lipid emulsion group- a dose of lipid emulsion was adminsitered before administering the local anesthetic. Results: After a few attemps to incannulate teh peripheral veins we tried the more complex approach of inferior vena cava, which ensured a secure access which allowed us to repetedly adminster the local anesthetic and the lipid emulsion. Conclusion: The presented experimental animal model of induced LAST and the protective effects of LE is one of the few described in the literature, is a reproducible model, feasible, simple, low cost and can be used as starting point in future LAST research.

BACKGROUND: Development of valvular substitutes meeting the performance criteria for surgical correction of congenital heart malformations is a major research challenge. The sheep is probably the most widely used animal model in heart valves regenerative medicine. Although the standard cardiopulmonary bypass (CPB) technique and various anesthetic and surgical protocols are reported to be feasible and safe, they are associated with significant morbidity and mortality rates. The premise of this paper is that the surgical technique itself, especially the perioperative animal care and management protocol, is essential for successful outcomes and survival. METHODS: Ten juvenile and adult female sheep aged 7.8-37.5 months and weighing 32.0-58.0 kg underwent orthotopic implantation of tissue-engineered pulmonary valve conduits on beating heart under normothermic CPB. The animals were followed-up for 6 months before scheduled euthanasia. RESULTS: Based on our observations, we established a guide for perioperative care, follow-up, and treatment containing information regarding the appropriate clinical, biological, and ultrasound examinations and recommendations for feasible and safe anesthetic, surgical, and euthanasia protocols. Specific recommendations were also included for perioperative care of juvenile versus adult sheep. CONCLUSION: The described surgical technique was feasible, with a low mortality rate and minimal surgical complications. The proposed anesthetic protocol was safe and effective, ensuring both adequate sedation and analgesia as well as rapid recovery from anesthesia without significant complications. The established guide for postoperative care, followup and treatment in sheep after open-heart surgery may help other research teams working in the field of heart valves tissue regeneration.

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Large bone defects are a medical concern as these are often unable to heal spontaneously, based on the host bone repair mechanisms. In their treatment, bone tissue engineering techniques represent a promising approach by providing a guide for osseous regeneration. As bioactive glasses proved to have osteoconductive and osteoinductive properties, the aim of our study was to evaluate by histologic examination, the differences in the healing of critical-sized calvarial bone defects filled with bioactive glass combined with adipose-derived mesenchymal stem cells, compared to negative controls. We used 16 male Wistar rats subjected to a specific protocol based on which 2 calvarial bone defects were created in each animal, one was filled with Bon Alive S53P4 bioactive glass and adipose-derived stem cells and the other one was considered control. At intervals of one week during the following month, the animals were euthanized and the specimens from bone defects were histologically examined and compared. The results showed that this biomaterial was biocompatible and the first signs of osseous healing appeared in the third week. Bone Alive S53P4 bioactive glass could be an excellent bone substitute, reducing the need of bone grafts.