Blood vessels can be damaged in many conditions such as trauma, cardiac disorders. If they are not repaired in time, it can lead to serious complications. So they can be repaired in two ways, either make a new one or replace it with a vessel from a different body part.
Both the options have their own limitations. Hence researchers are working on a third option, use the blood vessels from a dead body. Humacyte, a medical research company based in North Carolina is working on a new method for replacing blood vessels from tissues of its deceased donors. Their recent trials involving patients with kidney failure have shown positive results. Instead of swapping a damaged vessel with the one from the cadaver, they have developed a model in which the donated cells work in making a protein framework for the patient’s cells to grow.
This method has some great advantages over the the existing methods. If the blood vessels of the body did not work doctors usually found a replacement for them from another body part. The replacement must match the right size and shape, and this involves lot of work. But even then, the replaced vessel might not work and proper grafting may not take place. In some cases, a synthetic vessel can also work if it is replaced for a larger blood vessel, but it gets very risky for smaller blood vessels.
Hence, a midway approach is to make a frame for the blood vessel and let it be populated by the tissues from the patient’s body. This can be either a synthetic one or a framework of proteins from a cadaver.
The challenge in this method is to make sure the host cells move into their new ‘home’ and gets repopulated there. It is very crucial to identify which cells take part in the re-population of the implanted material and whether it is successful or not in the patient’s body.
The team at Humacyte seeded smooth muscle cells from cadavers onto a biodegradable mesh. The cells were fed nutrients and it produced a a 3D network of collagen proteins. After the disintegration of the mesh, a protein tube of 420 mm length and 6mm diameter formed. This was termed as human acellular vessel(HAV). All the foreign cells in the HAV were removed as they can be recognised as foreign substance and initiate immune response in the body.
This HAV was implanted in the upper arms of 60 persons with kidney failure. These blood vessels did not generate any significant immune response. Samples of HAV were obtained after a couple of years and it was found that the HAVs were populated with smooth muscle and endothelial cells and microvessels which supplied nutrients to the implant.
Thus the procedure was successful and researchers feel this can now be implemented in hundreds of patients and in future can be used in more complicated injuries such as cardiac injuries.