Evaluation of 3D Templated Synthetic Vascular Graft Compared with Standard Graft in a Rat Model: Potential Use as an Artificial Vascular Graft in Cardiovascular Disease

Although the number of vascular surgeries using vascular grafts is increasing, they are limited by vascular graft-related complications and size discrepancy. Current efforts to develop the ideal synthetic vascular graft for clinical application using tissue engineering or 3D printing are far from satisfactory. Therefore, we aimed to re-design the vascular graft with modified materials and 3D printing techniques and also demonstrated the improved applications of our new vascular graft clinically. We designed the 3D printed polyvinyl alcohol (PVA) templates according to the vessel size and shape, and these were dip-coated with salt-suspended thermoplastic polyurethane (TPU). Next, the core template was removed to obtain a customized porous TPU graft. The mechanical testing and cytotoxicity studies of the new synthetic 3D templated vascular grafts (3DT) were more appropriate compared with commercially available polytetrafluoroethylene (PTFE) grafts (ePTFE; standard graft, SG) for clinical use. Finally, we performed implantation of the 3DTs and SGs into the rat abdominal aorta as a patch technique. Four groups of the animal model (SG_7 days, SG_30 days, 3DT_7 days, and 3DT_30 days) were enrolled in this study. The abdominal aorta was surgically opened and sutured with SG or 3DT with 8/0 Prolene. The degree of endothelial cell activation, neovascularization, thrombus formation, calcification, inflammatory infiltrates, and fibrosis were analyzed histopathologically. There was significantly decreased thrombogenesis in the group treated with the 3DT for 30 days compared with the group treated with the SG for 7 and 30 days, and the 3DT for 7 days. In addition, the group treated with the 3DT for 30 days may also have shown increased postoperative endothelialization in the early stages. In conclusion, this study suggests the possibility of using the 3DT as an SG substitute in vascular surgery.

The Effect of Vascular Graft and Human Umbilical Cord Blood-Derived CD34+ Stem Cell on Peripheral Nerve Healing

AIM: There are many trials concerning peripheral nerve damage causes and treatment options. Unfortunately, nerve damage is still a major problem regarding health, social and economic issues. On this study, we used vascular graft and human cord blood derived stem cells to find an alternative treatment solution to this problem. MATERIAL AND METHODS: We used 21 female Wistar rats on our study. They were anesthetized with ketamine and we studied right hind limbs. On Group 1, we did a full layer cut on the right sciatic nerve. On Group 2, we did a full layer cut on the right sciatic nerve, and we covered synthetic vascular graft on cut area. On Group 3, we did a full layer cut on right sciatic nerve, and we covered the area with stem cell applied vascular graft. RESULTS: At the end of postoperative 8. weeks, we performed EMG on the rats. When we compared healthy and degenerated areas as a result of EMG, we found significant amplitude differences between the groups on healthy areas whereas there was no significant difference on degenerated areas between the groups. Then we re-opened the operated area again to reveal the sciatic nerve cut area, and we performed electron microscope evaluation. On the stem cell group, we observed that both the axon and the myelin sheet prevented degeneration. CONCLUSION: This study is a first on using synthetic vascular graft and cord blood derived CD34+ cells in peripheral nerve degeneration. On the tissues that were examined with electron microscope, we observed that CD34+ cells prevented both axonal and myelin sheath degeneration. Nerve tissue showed similar results to the control group, and the damage was minimal.

Predilation technique with balloon angioplasty to facilitate percutaneous groin access of large size sheath through scar tissue

Purpose Percutaneous remote access for endovascular aortic repair is an advantageous alternative to open access. Previous surgery in the femoral region and the presence of synthetic vascular grafts in the femoral/iliac arteries represent major limitations to percutaneous remote access. The aim of this study was to evaluate an original technique used for enabling percutaneous remote access for thoracic or abdominal endovascular aortic repair in patients with scar tissue and/or a vascular graft in the groin. Methods Twenty-five consecutive patients with a thoracic (11/25; 44%) or an aortic aneurysm (14/25; 66%) and with a synthetic vascular graft in the groin (16/25; 64%) or a redo groin access (9/25; 36%) were managed through the percutaneous remote access. In all patients, a percutaneous transluminal angioplasty balloon was used to predilate the scar tissue and the femoral artery or the synthetic vascular graft after preclosing (ProGlide®; Abbott Vascular, Santa Clara, CA, USA). In 10 patients, requiring a 20 Fr sheath, a 6 mm percutaneous transluminal angioplasty balloon was used; and in the remaining 15, requiring a 24 Fr sheath, an 8 mm percutaneous transluminal angioplasty balloon. Preclosing was exclusively performed using ProGlide®. Mean follow-up was 15 months. Results In all cases, stent-graft deployment was successful. There was one surgical conversion (4%; 1/25) due to bleeding from a femoral anastomosis. Two cases required additional percutaneous maneuvers (postclosing with another system in one patient and endoluminal shielding with stent-graft in the other patient). No pseudoaneurysm or access complication occurred during the follow-up. Conclusions Percutaneous access in redo groins with scar tissue and/or synthetic vascular graft using ultrasound-guided punction, preclosing with ProGlide® system and predilation with percutaneous transluminal angioplasty balloon to introduce large size sheath as used for endovascular aortic repair showed to be feasible, safe and with few local complications.