Blood Vessel Study Uncovers Beneficial Stem Cells
Posted on February 23, 2018
Osaka University stem cell researchers have successfully used adult endothelial stem cells to make fully functional blood vessels.
The Japanese researchers determined that vascular endothelial stem cells could regenerate damaged blood vessel tissue and treat a rare bleeding condition.
Stem cell therapy is gaining in popularity to repair damaged or defective tissues in the body.
Functioning blood vessels are vital to living a healthy life; they carry oxygen and nutrients through the body.
When blood vessels are diseased or defective, life-threatening illnesses can occur. Blood vessel conditions include cardiovascular disease, vascular disease and vasculitis, an inflammation of the blood vessels.
Peripheral artery disease and peripheral venous disease are also blood vessel conditions that have severe health implications. According to the U.S. Centers for Disease Control and Prevention, 8.5 million Americans over the age of 50 have peripheral artery disease and are at an increased risk of heart attack or stroke.
The scientists on the project have found a stem cell located in the blood vessel tissue that holds the key to new blood vessel cell generation.
In an earlier project, the Osaka researchers isolated endothelial cells from the innermost band of blood vessel tissue. These cells share the features and characteristics of stem cells.
The cells were identified using a functional analysis that searched for cell-surface protein markers that indicated their function as endothelial stem cells. The ability to identify the endothelial stem cells allowed researchers to isolate a like pool of endothelial stem cells for use in treatments.
One protein marker that the researchers identified was a glycoprotein called CD157, which is expressed in a small number of endothelial cells. To determine if the cells with CD157 were vascular endothelial stem cells, the researchers put their ability to regenerate to the test.
A key characteristic of stem cells is their ability to regenerate new cells without limit.
The team tested the cells’ regenerative properties by experimentally injuring mice, damaging the blood vessels that supply blood to the liver, and injecting them with CD157-positive endothelial cells isolated from the liver. The researchers guessed that the endothelial cells with CD157 proteins were stem cells with the ability to form new blood vessels.
Their findings were startling: One month after transplantation, the endothelial cells with CD157 protein had repaired damaged blood vessel tissue including portal veins, portal venules, sinusoids, arteries and hepatic venules, all the blood vessel tissue types found in a healthy and functional liver.
The researchers tested their findings again by using only one endothelial cell with CD157 in the mice. Despite the small number of cells being used, the researchers still saw new blood vessel tissue.
The researchers also found that these endothelial cells with CD157 help to maintain healthy tissues. They transplanted the cells into non-injured healthy mice and saw that the cells worked to restore normal blood vessel tissues in the liver.
“Stem cells not only repair damaged tissue, but also take care of healthy tissue, too,” said Dr. Joel Singer.
Singer is a New York physician who uses adipose fat stem cell therapy to treat patients with autoimmune, muscular and cardiac conditions.
In addition to the liver blood vessel repair portion of their research, the Osaka team also tested the ability of endothelial cells with CD157 protein to treat blood vessel-related diseases like hemophilia A. Patients with hemophilia A have a genetic mutation the prevents the liver from creating the blood-clotting factor known as factor VIII (FVIII).
When the study authors injected the endothelial cells with CD157 protein into mice with hemophilia A, they found that the cells began to generate new blood vessels in the liver and increased the level of FVIII in the blood from less than 1 percent to over 60 percent.
“The results of the research are encouraging and may mean new and effective treatment for blood vessel disorders,” said Singer.
Taku Wakabayashi, Hisamichi Naito, Jun-ichi Suehiro, Yang Lin, Hideya Kawaji, Tomohiro Iba, Tsukasa Kouno, Sachi Ishikawa-Kato, Masaaki Furuno, Kazuhiro Takara, Fumitaka Muramatsu, Jia Weizhen, Hiroyasu Kidoya, Katsuhiko Ishihara, Yoshihide Hayashizaki, Kohji Nishida, Mervin C. Yoder, Nobuyuki Takakura. CD157 Marks Tissue-Resident Endothelial Stem Cells with Homeostatic and Regenerative Properties. Cell Stem Cell, 2018;