The novel hybrid polycarbonate polyurethane / polyester three-layered large-diameter artificial blood vessel

Background The most common materials of artificial blood vessels are polyethylene terephthalate and polytetrafluoroethylene. But polycarbonate polyurethane (PCU) is an ideal material for vascular prostheses because of their excellent characteristics. As far as we know, our artificial blood vessel is the first type of hybrid PCU/polyester three-layered large-diameter artificial blood vessel in the world. Objective The purpose of this preclinical animal experiment is to evaluate the hemocompatibility, histocompatibility, effectiveness, and safety of the three-layered large-diameter artificial blood vessel in sheep. Methods The artificial blood vessels took place of the initial segments of the sheep’s thoracic aorta by end-to-end anastomosis. Results All of the 14 sheep are male, their average body weight (BW) was 30.57 ± 3.95 kg. All 14 artificial blood vessels successfully replaced the thoracic aortas. 5 sheep did not survive to the end of the experiment, while the remaining 9 sheep did. After the surgery, the blood biochemical and blood routine indicators fluctuate slightly within the normal range. The angiography showed that the implanted artificial blood vessels were unobstructed without obvious stenosis or expansion. 24 weeks after surgery, the lumen surfaces of the artificial blood vessels were covered by endothelia in different degrees, and the average endothelialization rate was 69.44% (range: 20% to 100%). Conclusions This artificial blood vessel is the first to use PCU in large-diameter artificial vascular grafts. It has excellent blood compatibility, wonderful biocompatibility, high endothelialization rate, and 100% patency.

Development of artificial blood vessels made of new materials, used for vascular access in renal dialysis

It can take many years to find a matched kidney donor and, in some cases, a matched donor is never found. Dialysis machines and methods of accessing a patient's cardiovascular system mean patients can live well whilst waiting for a transplant. Patients must undergo one of two surgical procedures before their first haemodialysis; receiving either an arteriovenous fistula or an arteriovenous graft, which join the artery to the vein and facilitate the transfer of blood from body to machine. If a graft is needed, an operation to insert a polytetrafluoroethylene (PTFE) based device is required but complications can arise in the form of blockages. Denan Jin, Department of Innovative Medicine, Osaka Medical and Pharmaceutical University, Japan, has spent years conducting research on the issues related to PTFE device blockage. He worked with his mentor Professor Mizuo Myazaki before his retirement and his colleague Professor Shinji Takai, and these collaborations led to understanding of the major causes of these blockages. Jin and his team are working to develop means to increase the longevity of PTFE grafts. The researchers have discovered two key mechanisms through which the grafts become blocked, which has led to the identification of two possible routes for preventing blockages. These relate to fibroblasts and the researchers have also identified the enzyme chymase as a key intermediate in the process of fibroblast recruitment. Jin and the team are proposing the use of an alternative to PTFE and the development of an effective chymase inhibitor to reduce the recruitment of fibroblasts to the graft site.

iBTA-Induced Biotube® Blood Vessels: 2020 Update

Blood access is a lifeline for dialysis patients. However, serious problems such as stenosis or obstruction of access blood vessels, which are life-threatening conditions in daily clinical practice, still remain. One of the most promising candidates for solving these problems may be Biotube blood vessels. More than 20 years have passed since the development of in-body tissue architecture (iBTA), a technology for preparing tissues for autologous implantation in patients. The tissues obtained by iBTA do not elicit immunological rejection, which is one of the ultimate goals of regenerative medical engineering; however, their practical applications were quite challenging. The seemingly unorthodox iBTA concepts that do not follow the current pre-established medical system may not be readily accepted in general medicine. In contrast, there are many diseases that cannot be adequately addressed even with the latest and most advanced medical technology. However, iBTA may be able to save patients with serious diseases. It is natural that the development of high-risk medical devices that do not fit the corporate logic would be avoided. In order to actively treat such largely unattached diseases, we started Biotube Co., Ltd. with an aim to contribute to society. Biotubes induced by iBTA are collagenous tubular tissues prepared in the patient’s body for autologous implantation. The application of Biotubes as tissues for vascular implantation has been studied for many years. Biotubes may have excellent potential as small-diameter artificial blood vessels, one of the most difficult to clinically achieve. Their possibility is currently being confirmed in preclinical tests. Biotubes may save hundreds of thousands of patients worldwide annually from amputation. In addition, we aim to eliminate the recuring access vascular problems in millions of dialysis patients. This study provides an update on the current development status and future possibilities of Biotubes and their preparation molds, Biotube Makers.

A case of simultaneous laparoscopic surgery for double cancer comprising multiple early gastric cancer and advanced sigmoid colon cancer after revascularization

Background Traditionally, the surgery for simultaneous double cancer of the stomach and colon required a large incision to the upper and lower region of the abdomen. In this case, an artificial blood vessel was located under the skin after revascularization. Considering ischemia due to graft compression by incision retractor during laparotomy, this was difficult to do. This is a report on laparoscopic surgery for simultaneous double cancer of the stomach and colon after revascularization. Case presentation A 69-year-old man had early gastric cancer and advanced sigmoid colon cancer. He had suffered from thromboangitis obliterans and has undergone revascularization many times due to poor blood flow in his lower limbs. He had had some artificial blood vessels inserted under the skin, confirmed by blood vessel construction image by preoperative computed tomography (CT). There was a bypass vessel from the left axillary artery to the left femoral artery under the skin of the left thoracoabdominal. In addition, there were two bypass vessels from the left external iliac artery to the right femoral artery under the skin of the lower abdomen. One of the two bypasses was occluded. In the blood flow to the intestinal tract, the inferior mesenteric artery was already occluded. Peripheral blood flow in the common iliac artery depended on blood flow from the artificial blood vessel, and blood flow from the internal iliac artery to the rectum was poor. Laparoscopic Hartmann’s operation was performed for Stage II B (UICC 8th Edition) sigmoid colon cancer. Because the blood flow in the intestinal tract on the anal side was poor, we thought that anastomosis was at a high risk for leakage. Laparoscopic total gastrectomy was also performed simultaneously for two Stage I (UICC 8th edition) gastric cancers in the cardia and body. The location of the port site and stoma was carefully determined preoperatively to prevent damage and infection to the artificial blood vessels. Minimal invasive surgery was performed using laparoscopic surgery. Conclusions Laparoscopic surgery with small incisions is useful for patients with double cancer who need an approach to the upper and lower abdomen. Furthermore, laparoscopic surgery has less interference on graft in patients with artificial blood vessels under the skin by intraperitoneal approach.

The Normal and Brain Tumor Vasculature: Morphological and Functional Characteristics and Therapeutic Targeting

Glioblastoma is among the most common tumor of the central nervous system in adults. Overall survival has not significantly improved over the last decade, even with optimizing standard therapeutic care including extent of resection and radio- and chemotherapy. In this article, we review features of the brain vasculature found in healthy cerebral tissue and in glioblastoma. Brain vessels are of various sizes and composed of several vascular cell types. Non-vascular cells such as astrocytes or microglia also interact with the vasculature and play important roles. We also discuss in vitro engineered artificial blood vessels which may represent useful models for better understanding the tumor–vessel interaction. Finally, we summarize results from clinical trials with anti-angiogenic therapy alone or in combination, and discuss the value of these approaches for targeting glioblastoma.