MONDAY, July 15 (HealthDay News) -- Scientists who used adult stem cells to create functional and long-lasting blood vessels in mice say this research could lead to new treatments for cardiovascular disease.

The Massachusetts General Hospital team used so-called induced pluripotent stem cells (iPSCs) -- which are reprogrammed adult cells with many of the characteristics of embryonic stem cells -- from both healthy adults and people with type 1 diabetes to generate blood vessels on the outer surface of the brain or under the skin of mice.

The study was published online July 15 in the journal PNAS Early Edition.

"The discovery of ways to bring mature cells back to a 'stem-like' state that can differentiate into many different types of tissue has brought enormous potential to the field of cell-based regenerative medicine, but the challenge of deriving functional cells from these iPSCs still remains," study co-senior author Rakesh Jain, director of the Steele Laboratory for Tumor Biology at Mass General, said in a hospital news release.

"Our team has developed an efficient method to generate vascular precursor cells from human iPSCs and used them to create networks of engineered blood vessels in living mice," Jain said.

Being able to regenerate or repair blood vessels could be a major advance in the treatment of cardiovascular disease -- the leading cause of death in the United States -- as well as other conditions caused by blood vessel damage, such as the vascular complications of diabetes.

Commenting in the news release, study co-lead author Dr. Rekha Samuel said: "The potential applications of iPSC-generated blood vessels are broad -- from repairing damaged vessels supplying the heart or brain to preventing the need to amputate limbs because of the vascular complication of diabetes." Samuel, formerly with the Steele Laboratory, is now at the Christian Medical College, in Vellore, India.

While the findings of the new study are promising, scientists note that research involving animals often fails to produce similar results in humans.

-- Robert Preidt

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Scientists Create Blood Vessels in Mice Using Human Stem Cells

July 16, 2013 Magnets could be a tool for directing stem cells' healing powers to treat conditions such as heart disease or vascular disease.

By feeding stem cells tiny particles made of magnetized iron oxide, scientists at Emory and Georgia Tech can then use magnets to attract the cells to a particular location in the body after intravenous injection.

The results are published online in the journal Small and will appear in an upcoming issue.

The paper was a result of collaboration between the laboratories of W. Robert Taylor, MD, PhD, and Gang Bao, PhD. Taylor is professor of medicine and biomedical engineering and director of the Division of Cardiology at Emory University School of Medicine. Bao is professor in the Wallace H. Coulter Department of Biomedical Engineering at Georgia Tech and Emory University. Co-first authors of the paper are postdoctoral fellows Natalia Landazuri, PhD, and Sheng Tong, PhD. Landazuri is now at the Karolinska Institute in Sweden.

The type of cells used in the study, mesenchymal stem cells, are not embryonic stem cells. Mesenchymal stem cells can be readily obtained from adult tissues such as bone marrow or fat. They are capable of becoming bone, fat and cartilage cells, but not other types of cell such as muscle or brain. They secrete a variety of nourishing and anti-inflammatory factors, which could make them valuable tools for treating conditions such as cardiovascular disease or autoimmune disorders.

Magnetized iron oxide nanoparticles are already FDA-approved for diagnostic purposes with MRI (magnetic resonance imaging). Other scientists have tried to load stem cells with similar particles, but found that the coating on the particles was toxic or changed the cells' properties. The nanoparticles used in this study have a polyethylene glycol coating that protects the cell from damage. Another unique feature is that the Emory/Tech team used a magnetic field to push the particles into the cells, rather than chemical agents used previously.

"We were able to load the cells with a lot of these nanoparticles and we showed clearly that the cells were not harmed," Taylor says. "The coating is unique and thus there was no change in viability and perhaps even more importantly, we didn't see any change in the characteristics of the stem cells, such as their capacity to differentiate. This was essentially a proof of principle experiment. Ultimately, we would target these to a particular limb, an abnormal blood vessel or even the heart."

The particles are coated with the nontoxic polymer polyethylene glycol, and have an iron oxide core that is about 15 nanometers across. For comparison, a DNA molecule is 2 nanometers wide and a single influenza virus is at least 100 nanometers wide.

The particles appear to become stuck in cells' lysosomes, which are parts of the cell that break down waste. The particles stay put for at least a week and leakage cannot be detected. The scientists measured the iron content in the cells once they were loaded up and determined that each cell absorbed roughly 1.5 million particles.

Once cells were loaded with iron oxide particles, the Emory/Tech team tested the ability of magnets to nudge the cells both in cell culture and in living animals. In mice, a bar-shaped rare earth magnet could attract injected stem cells to the tail (see photo). The magnet was applied to the part of the tail close to the body while the cells were being injected. Normally most of the mesenchymal stem cells would become deposited in the lungs or the liver.

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Steering stem cells with magnets