A groundbreaking recent approval by the Food and Drug Administration (FDA) has paved the way for allowing medical doctors in the United States to implant lab-grown blood vessels to treat children who have severely malformed congenital heart valves, ventricles or arteries. By using tissue engineering techniques, scientists around the world have been able to grow blood vessels using matrix scaffolds to help mold the growing tissue and grafts around the scaffolds. This upcoming clinical trial will be conducted with the hope that naturally grown arteries and other blood vessels can be grafted and allowed to be surgically implanted onto children (blue babies) which typically die within a year of birth. The Children’s Hospital of Pittsburgh offers cutting-edge services for treating babies with pediatric vascular anomalies and its staffed with over eleven physicians specialized in this field. The hospital uses a multi-disciplinary team approach that analyzes a case by case scenario and determines the appropriate approach to each congenital problem
The recent mounting experimental evidence lead by two key scientists from the University of Yale helped convinced the FDAto approve the clinical trial and has increased our understanding of how the blood vessel grafts really work at the molecular level. Much of the experimental was performed to help the approval process by the FDA and the project was lead by Dr. Christopher Breuer, a pediatric surgeon form the Yale University and Dr. Shinoka, a cardiologist. They are the main principle investigators who will be conducting the clinical trial to test the safety and efficacy of lab grown blood vessels in eight US patients. In brief, the team of scientists used different matrix scaffolds that are seeded with the patient’s own bone marrow mononuclear cells in the lab and use different chemical factors to coax the cells into forming a layer of a functional graft or a complete functional blood vessel. The authors of the project showed that the grafts generated a healthy blood vessel with a proper arrangement and organization of smooth muscle and endothelial layers similar to a normal blood vessel. Interestingly, the scaffold that help to grow the blood vessel in the lab do degrade a few weeks after implantation in a patient and are completely replaced by the host’s own cells suggesting that the blood vessels grow their own natural environment once implanted inside the experimental animals. The scientists further showed that the lab grown blood vessels can be implanted in other lab animals without any signs of immune rejections but only saw a mild phase of inflammation which is part of the healing process following the implantation. In addition, they observed that the human cells that helped to formed the blood vessel in the lab disappeared once implanted onto a lab animal and was repopulated by the host’s cells. Overall, these studies have been well documented and summarized in an article published in this months issue of Science.
Not too long ago, Tissue Genesis, a Hawaii based biotech company, has gained national attention for being one of the pioneer companies to start using stem cells naturally derived from the fat tissue of patient in order to coat the inner lining of vascular grafts that can be used to treat peripheral (arms/legs) vascular diseases in patients. The impact of this clinical trial can also increase the availability of stem cells for other practical medical uses.
The results are exciting not just in the field of vascular biology in the sense that embryonic derived or induced pluripotent stem cells were not necessary to allow for the generation of lab-grown blood vessels. More importantly, it is possible to completely eliminate immune rejection, reduce the need for immunosuppressants and provide a lifetime of high quality of life for children with vascular complications. More news will be released following the first phase results of the clinical trial this year!
For a more specific in-depth review of how tissue engineering has advanced the techniques for growing organs and tissue in the lab, please click on the following link to get access to the article.
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