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Blood vessels damaged by cardiovascular disease can become a serious problem if they are not repaired in time. To do this, you have two options: replace it with a ship taken from another part of your body or create a new one from scratch.
Option A has its limits. And the types of synthetic vessels that we currently use for option B are not without risk. The researchers are studying option C: ask a corpse to make one.
The US biotechnology company Humacyte has advanced a radical new method of building replacement blood vessels using tissue from recently deceased donors.
The results of two recent phase II clinical trials in patients with end-stage renal failure showed that their laboratory-developed vessels were functioning exactly as intended.
Rather than trading a damaged ship against a dead part of a corpse and risking being rejected, the company has come up with a procedure that uses the given cells to create a protein structure for the growth of the patient's cells.
This approach promises big advantages over current procedures.
If a blood vessel does not work as expected, surgeons usually look for a replacement product from another part of your body.
Hopefully, they will find a model of appropriate size and shape that does not play a vital role, but it is not an easy process. Even if doctors find such a replacement, there is a risk that the transplant simply will not take.
Meanwhile, a synthetic graft allows medical specialists to adapt the replacement to the damaged part. Tubes made from various polymers can do the business for larger vessels, but when it comes to smaller pipes, scarring becomes a problem.
A mid-way approach is to produce a frame for a blood vessel and populate it with the patient's own tissue. It can be a synthetic network, or a matrix of proteins from the vessels of a donor and its own cells.
Even here, a major obstacle is to encourage host cells to move quickly to their new home. "If you build it, they will come" is not always true when it comes to developing the infrastructure needed for tissue growth.
"Identifying when and which types of host cells participate in repopulation and remodeling of implanted vascular material becomes critical to understanding their long-term success or failure in patients," the researchers said in their report.
Humacyte researchers are learning to manage this process by taking the proper muscles and epithelial tissues from a cadaver and manipulating them to grow on a biodegradable mesh.
After eight weeks of development in a bioreactor, the donor cells are removed. All that remains at the end is a rigid tissue of proteins called a human acellular vessel, or HAV, capable of carrying blood on its own.
If the donor cells do not attract the attention of the immune system, the host organism can not reject anything. Protein tubes are also much easier to produce and store in sufficient quantities.
"The removal of the cells is important so that the vessels can be manufactured in large quantities and stored on shelves in operating theaters to be implanted in any patient," said the director. 39, exploitation, Humacyte, Heather Prichard, to the organizers Discovery blog author, Roni Dengler.
Unlike other scaffolds, HAVs are not subjected to the same procedures of preserving or destroying cells as it is believed to interfere with the uptake of the blood vessels cells of the host.
To test the newly developed structures, the team actually grafted HAVs into the arms of 60 American and Polish volunteers with kidney failure.
Ultrasound on vessels up to one year after implantation showed an insignificant drop in blood flow, suggesting that they were doing their job as planned.
In recent years, 16 HAV segments have been removed for a variety of reasons, allowing researchers to take a closer look at how host cells have settled into transplants.
As expected, the cadaver-produced protein matrix had developed layers of appropriate tissue resembling those of the patient's blood vessels. HAVs even showed clear signs of repair around sites where cannulation needles had perforated the vessel.
Heart disease remains a leading cause of death in most post-industrial countries.
Of course, changing our way of life is a way to avoid an early grave. But improving treatments with quick access to safe and reliable replacement vessels will certainly save the lives of those in need.
This research was published in Translational medicine science.
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