More than a decade ago, a team led by University of Florida neurologist Michael Pyle published the first blood-sign study of blood flow in the brain, which had never been done before. 

The study, published in the Journal of Neurology and Neurosurgery in 2013, revealed that the brain had a high concentration of blood vessels. 

In his book Blood Sign, Pyle wrote, “The blood vessels were connected to the blood-brain barrier in the form of blood capillaries, and it was thought that these capillary structures would be responsible for regulating blood flow.” 

The capillar structures had not been shown to be blood vessels in humans before the study.

But in mice, a group of scientists, led by Pyle, showed that they do carry a blood capillary, a piece of protein that forms the blood vessels’ inner wall. 

That protein, called a blood endothelial cell, is a type of blood vessel, and scientists were able to show that the blood capilla could actually be a type that is more efficient at transporting nutrients and oxygen to the brain. 

After the blood endothelium had been injected into mice, Pyl’s team discovered that when they injected the endothelial cells into the brain at the right time, they were able, by altering blood flow to different parts of the brain and altering how they were attached to the surrounding blood vessels, to cause the animals to grow blood vessels instead of the capillae. 

“Our data showed that the capillary endothelia in mice could be manipulated to grow new blood vessels,” Pyle said.

“This was the first time we had shown that blood vessels could be grown from the capilla endotheli, and we have now shown that the same thing can be done in humans.” 

Pyle and his team have been able to demonstrate that blood vessel growth and contraction are different in the human brain than in mice.

The team has found that the human blood vessels can become more vascular, while mice that are fed with a diet low in calcium and other nutrients are more prone to develop atherosclerosis, the buildup of fatty deposits in the arteries that are responsible for plaque buildup in the blood. 

According to the team, the study also revealed that there are different kinds of blood cell types in humans.

“The first step was to identify which types of blood cells are involved in blood vessel formation,” Pyl said.

 “There is evidence that there is a relationship between the number of different blood cell species and the ability of blood to travel across the blood brain barrier,” he continued.

“These findings suggest that a combination of these factors may help to regulate blood flow through the brain.”

 Pyl said that there was evidence that the type of endothelial cells in the mouse brain could also have a role in the development of Alzheimer’s disease, as well.

“We found that endothelial-type cells have been shown in mice to be involved in vascular remodeling and that their production may be an important component of vascular disease,” he said. 

Pyles said that one of the reasons why the blood cell density in humans is so high is that it is the only blood cell type in the body that has an affinity for oxygen. 

“[There is] a lot of variability in blood cell count across the body, and this variability has to do with what kind of blood is circulating,” he explained.

“So there is the possibility that there may be differences in how the blood cells work with regard to oxygen.

There may be a difference in the efficiency of those blood cells. 

While it is unclear exactly how the human endothelios are responsible, Pyles said it was clear that blood cells do not form from a single piece of tissue.

When it comes to the role of blood in the process of blood clotting, Pels said, “the important thing is that the flow of blood does not become a bottleneck, which would be bad for blood clot prevention.” “

[We] showed that we can make blood from a number of blood stem cells that are very specialized, which is why they are called endotheliopheres,” he added.

When it comes to the role of blood in the process of blood clotting, Pels said, “the important thing is that the flow of blood does not become a bottleneck, which would be bad for blood clot prevention.” 

According for the research, the endothelio cells in blood stem cell cells that produce blood stem, and then in endothelial stem cells in various organs in the same body are the “primary source of circulating oxygen in the circulatory system,” according to the study’s lead author, Ravi Gupta, MD, PhD. The findings were supported by grants from the National Institutes of Health (R01 AG04976-04).