"Perfect" human blood vessels grown in the laboratory are now a thing of the past

An international team of scientists claims to have made a first: three-dimensional replicas of human blood vessels grown in a petri dish. This remarkable achievement, detailed in a new document released Wednesday in Nature, should allow us to better understand and study debilitating diseases such as diabetes.

People with diabetes, a disease characterized by high blood sugar levels, often develop poor blood circulation. Heart attacks, strokes and even limb amputation may occur. Scientists can use animals, including mice, to study the progression of diabetes. But these mouse models do not capture all aspects of diabetes that we see in humans, including the damage it causes to blood vessels.

Ideally, you would like to see the effects of a disease on an object that is as close to humans as possible. Tiny organs developed in the laboratory, or organoids as scientists call them, have emerged in recent years as an enticing option to achieve this. However, researchers in the current study have indicated so far that we have not really recreated human blood vessels in the laboratory. But those made by this research team are "perfect," according to a press release from the University of British Columbia.

"Our organoids are very similar to human capillaries, even at the molecular level, and we can now use them to directly study the diseases of blood vessels on human tissue," wrote lead author Reimer Wimmer, a postdoctoral researcher at the University of California. Institute of Molecular Biotechnology of Canada. Austrian Academy of Sciences (IMBA) in Vienna, said in a statement.

Organoids were cultured from stem cells, immature cells capable of transforming into several types of cells. As in humans, it was found that the replicas had a network of capillaries covered with a basement membrane, a kind of connective tissue that helps support and structure the vessels.

Wimmer and his team went further with their replicas by transplanting them into mice lacking the immune system (a step that would prevent them from rejecting the donor tissue). Organoids easily entered their new home, connecting to the native circulatory system of the mouse, and further developed into a network resembling a tree of arteries, small veins and arterioles (branches of an artery). flowing in the capillaries).

In addition, they have even been able to recreate "diabetic" blood vessels, characterized by a thickening of the basement membrane. In experiments on mice and previous research, they found that a signaling pathway involving NOTCH-3 protein played a key role in the formation of thickening seen in the blood vessels of people with diabetes. The blockage of another protein that targets the NOTCH-3, γ-secretase, also seemed to prevent this damage from occurring.

According to the researchers, the results of these experiments show that these vessels may be a better model for studying diabetes than traditional mouse models. And given the importance of our circulatory system for the rest of the body, the potential of these replicas developed in the laboratory goes far beyond diabetes research.

"Every organ in our body is linked to the circulatory system," said in a statement the lead author, Josef Penninger, founding director of IMBA and current director of the Life Sciences Institute at the University of British Columbia. British. "Vascular organoids generated from [stem] Cells represent a game-changing model, allowing us to unravel the etiologies and treatments of many vascular diseases, from diabetes to Alzheimer's disease, to cardiovascular disease, wound healing or stroke. ".

The blood vessels are only the last frontier of the development of organoids. Scientists have already created miniature versions of the stomach, lungs and even the developing brain. These organoids have been used to study the effects of everything from cystic fibrosis to Zika virus.