After cancer, vascular diseases are the leading causes of death for Canadians. Heart attacks and strokes claim 65,000 lives each year, while diabetes—which can cause degeneration of the veins—kills another 7,000.
Now, for the first time, scientists are able to grow perfectly formed human blood vessels outside of the body—a move that researches hope will help identify how vascular diseases progress.
The study—presided over by senior author Josef Penninger of UBC—presents a method of growing vessels in a Petri dish. These vessels are called organoids: a collection of stem cells grown into a structure that mimics human organs. The team aims to use the findings to identify how to prevent negative changes to blood vessels.
“Being able to build human blood vessels as organoids from stem cells is a game changer,” said Penninger, the Canada 150 research chair in functional genetics and director of the Life Sciences Institute at UBC. “Every single organ in our body is linked with the circulatory system. This could potentially allow researchers to unravel the causes and treatments for a variety of vascular diseases, from Alzheimer’s disease, cardiovascular diseases, wound healing problems, stroke, cancer and, of course, diabetes.”
The constructed vessels are also able to work as living tissues inside organisms. When researchers transplanted the organoids into mice, they found that they developed into perfectly functional human blood vessels, including arteries and capillaries. The discovery indicates that it is possible not just to grow the tissues outside of the body, but also to grow a functional human vascular system in another species.
“What is so exciting about our work is that we were successful in making real human blood vessels out of stem cells,” said Reiner Wimmer, the study’s first author and a postdoctoral research fellow at the Institute of Molecular Biotechnology at the Austrian Academy of Sciences. “Our organoids resemble human capillaries to a great extent, even on a molecular level, and we can now use them to study blood vessel diseases directly on human tissue.”
The team has already put the engineered blood vessels to the test in order to map how vascular diseases operate. Initially, researchers focused on the symptoms of diabetes—a disease that one in five Canadians suffers from, and is a factor in the deaths of an estimated one in ten.
A feature of diabetes is the abnormal thickening of the basement membrane of blood vessels. This prevents the delivery of oxygen and nutrients to cells and tissues, which can cause heath issues such as kidney failure, heart attacks, strokes, blindness, and the need for amputation.
When researchers exposed the blood vessel organoids to a “diabetic” environment in a Petri dish, they observed the thickening of the basement membrane, as in live patients. They then searched for chemical compounds that could block that symptom. The scientists found that none of the current anti-diabetic medications had any effect on the enlarged membranes, but that an inhibitor of y-secretase—a type of enzyme in the body—could prevent the thickening of the blood vessel walls. Their research suggests—at least in animal models—that blocking y-secretase could be helpful in treating the symptoms of diabetes.
The scientists say that their findings could be instrumental in discovering the underlying causes of vascular disease, and could be used to develop and test new treatments for those afflicted.
Kate Wilson is the Technology Editor at the Georgia Straight. Follow her on Twitter @KateWilsonSaysMore