Artificial vessels for microsurgery
Researchers have been working for a long time on the creation of bioengineered tissue implants for the restoration or replacement of tissues and organs damaged as a result of injury or various diseases. However, the success of this work depends very much on the possibility of creating a reliable connection between the blood vessels of the implant and the recipient's vascular network, which is especially difficult when working with thin vessels.
Specialists at Boston University, working under the guidance of Professor Joe Tien, have developed a method that allows the use of the thinnest collagen tubes to form such compounds critical for graft engraftment.
Successful implantation of a collagen tube into the femoral artery of a rat.
Collagen is a compound that is part of the body. It is completely biocompatible and is an excellent substrate for cell adhesion, therefore its use is associated with a significantly lower risk of complications compared to the use of artificial materials.
Usually, collagen contains up to 99% water, which makes it unsuitable for the use of "cross-linking" technology, often used to increase the strength of polymer materials by binding molecules together. However, the authors demonstrated that drying a large fragment of collagen on a round rotating rod (like a spit) ensures its compaction and compression to the diameter of the rod. The resulting tubular structure can be cross-linked to give it additional strength.
The combination of drying and cross-linking proved to be the key to success. When implanting such hardened collagen tubes into the femoral artery of a rat, they allowed to restore and maintain blood circulation for 20 minutes, demonstrating strength similar to that of an animal artery.
Scheme of formation of tubes with a diameter of 1 mm from dried collagen.
Currently, the authors are working on increasing the time period during which the transplant will allow normal blood flow to be maintained. The use of "naked" collagen tubes is very likely to trigger the process of thrombosis, however, this risk can be reduced by populating their surface with endothelial cells, usually lining the inner surface of blood vessels and growing well on collagen-coated surfaces. Researchers have already demonstrated the possibility of creating such cell-covered implants and are planning experiments to study their functionality in the conditions of the body for a long period of time.
Article by Xuanyue Li et al. Generation, Endothelialization, and Microsurgical Suture Anastomosis of Strong 1-mm-Diameter Collagen Tubes is published in the journal Tissue Engineering Part A.
Evgeniya Ryabtseva
Portal "Eternal youth" http://vechnayamolodost.ru based on the materials of the National Institute of Biomedical Imaging and Bioengineering: Tiny bioengineered blood vessel grafts aid delicate microsurgeries. https://www.nibib.nih.gov/news-events/newsroom/tiny-bioengineered-blood-vessel-grafts-aid-delicate-microsurgeries-1
04.04.2017