University of Minnesota
University of Minnesota

Scientists Bioengineer Arteries That Could Potentially Grow Inside the Body

University of Minnesota
University of Minnesota

Welcome to the future. Scientists have created arteries that can be safely implanted and continue growing in their hosts. They published a report of their progress today, September 28, in the journal Nature Communications.

Transplanted organs and tissue face several major obstacles to success. First, there’s ensuring the transplant is right and safe for the recipient. Then there’s the possibility that the recipient’s body will reject the new part. Finally, there’s the need for the implanted materials to cooperate with the cells around them, to grow and work together. Scientists have made major headway on the first two issues over the last few decades. But when it comes to coaxing transplanted parts to grow, we’re really just getting started.

Growth is especially important—and hard to produce—in blood vessel transplants. Scientists have found ways to make it happen, but they involve growing new vessels in the lab from scratch, using each patient’s own cells. The customization process is expensive and time-intensive, which seriously limits its use.

So a team of researchers at the University of Minnesota set out to find another way. They essentially wanted to build a generic or base model of the pulmonary artery—one that could be kept on hand in a hospital and used as needed.

They started with sheep. The team took samples of sheep skin cells and mixed them with a clotting agent and calcium chloride to give them rigidity, then pumped them into a tube-shaped glass mold. As the cells took shape in the tubes, the researchers infused them with nutrient fluids to give them the shape and flexibility they would need. They then transferred the cells to a bioreactor for another five weeks of maturation and stretching.

Once the arteries had grown and stretched to the right size, the team rinsed them in chemicals that stripped out all the original skin cells, a process known as decellularization. All that remained were the newly grown structures themselves; the shapes of blood vessels, with none of the immune system–triggering cells.

The new arteries were then implanted in three 8-week-old lambs. The lambs were patched up, then monitored with regular ultrasound scans 8 weeks, 30 weeks, and 50 weeks after their surgery. After the last scan, the lambs were euthanized and their arteries removed and dissected.

The artificial blood vessels had fared incredibly well. Not only did the lambs’ bodies not reject the grafts, but they seemed to embrace them. The transplanted arteries entered the lambs’ bodies as scaffolds, essentially, yet by the time the animals reached young adulthood the scaffolds were filled and composed of their own cells. The blood vessels grew with their owners, serving them well.

Jeffrey Harold Lawson is a professor of vascular surgery at Duke University. "This appears to be very exciting work and continues to support the emerging field of vascular tissue engineering," Lawson, who was unaffiliated with the study, told mental_floss. "It is very exciting to see the vessels grow over time with the sheep and repopulate with the hosts' own cells. If work like this continues to make both preclinical and clinical progress, it could revolutionize the field of pediatric cardiac surgery and potentially avoid reoperative procedures for thousands of young children."

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Jamie McCarthy/Getty Images for Bill & Melinda Gates Foundation
Bill Gates is Spending $100 Million to Find a Cure for Alzheimer's
Jamie McCarthy/Getty Images for Bill & Melinda Gates Foundation
Jamie McCarthy/Getty Images for Bill & Melinda Gates Foundation

Not everyone who's blessed with a long life will remember it. Individuals who live into their mid-80s have a nearly 50 percent chance of developing Alzheimer's, and scientists still haven't discovered any groundbreaking treatments for the neurodegenerative disease [PDF]. To pave the way for a cure, Microsoft co-founder and philanthropist Bill Gates has announced that he's donating $100 million to dementia research, according to Newsweek.

On his blog, Gates explained that Alzheimer's disease places a financial burden on both families and healthcare systems alike. "This is something that governments all over the world need to be thinking about," he wrote, "including in low- and middle-income countries where life expectancies are catching up to the global average and the number of people with dementia is on the rise."

Gates's interest in Alzheimer's is both pragmatic and personal. "This is something I know a lot about, because men in my family have suffered from Alzheimer’s," he said. "I know how awful it is to watch people you love struggle as the disease robs them of their mental capacity, and there is nothing you can do about it. It feels a lot like you're experiencing a gradual death of the person that you knew."

Experts still haven't figured out quite what causes Alzheimer's, how it progresses, and why certain people are more prone to it than others. Gates believes that important breakthroughs will occur if scientists can understand the condition's etiology (or cause), create better drugs, develop techniques for early detection and diagnosis, and make it easier for patients to enroll in clinical trials, he said.

Gates plans to donate $50 million to the Dementia Discovery Fund, a venture capital fund that supports Alzheimer's research and treatment developments. The rest will go to research startups, Reuters reports.

[h/t Newsweek]

Eye Doctors Still Use This 100-Year-Old Test for Color Blindness

You may have seen them at your ophthalmologist's office: large circular diagrams made up of colored dots. People with normal vision are able to discern a number among the dots of contrasting colors. People who are color blind might see only a field of spots.

These elegant, deceptively modern drawings were published 100 years ago by a Japanese ophthalmologist, Shinobu Ishihara. Thanks to the designs' simplicity and diagnostic accuracy, the Ishihara test is still the most popular and efficient way to identify patients with color vision deficiencies.

Born in Tokyo in 1879, Ishihara studied medicine at the prestigious Tokyo Imperial University on a military scholarship, which required him to serve in the armed forces. After graduating in 1905, he worked for three years as a physician specializing in surgery in the Imperial Japanese Army, and then returned to the university for postgraduate studies in ophthalmology. In his research, Ishihara focused on identifying and recruiting soldiers with superior vision, thereby increasing the overall effectiveness of the military. And that became of prime importance to Japan beginning in 1914.

As World War I spread across Europe, Asia, and the Pacific, the Japanese army asked Ishihara to develop a better way to screen draftees for color vision problems. The most popular method at the time was the Stilling test, invented by German ophthalmologist Jakob Stilling in 1878 as the first clinical color vision test. (Previous tools had asked patients to identify the colors of wool skeins or illuminated lanterns—useful skills for sailors and railway conductors, but an imprecise method for diagnosing vision issues.)

"Though popular, 'the Stilling' retained a distinctly 19th-century flavor, more treatise-like and less diagnostically incisive," according to Eye magazine.

Shinobu Ishihara
Wellcome Images // CC BY 4.0

Japanese army officials requested a new diagnostic tool that was easier to administer and interpret. The test Ishihara began to develop was based, like Stilling's, on the principle of pseudo-isochromatism—a phenomenon in which two or more colors are seen as the same (or isochromatic) when they're actually different. A person with normal vision could easily see the difference, while people with red-green deficiency, the most common form of color blindness, would have difficulty distinguishing those two opposing colors. Those with blue-yellow color blindness, a less common type, would have a hard time discerning reds, greens, blues, or yellows.

Ishihara hand-painted circular designs comprised of small dots of different areas and colors so that variations in the design could be discerned only by color and not shape, size, or pattern. Hidden in the field of dots was a figure of a contrasting color that people with normal vision could see, while those with deficiencies could not. Other plates in the series were designed to show figures that would be visible only to people with deficiencies. When physicians displayed the diagrams, patients said or traced the visible figure within the circle without needing to use ambiguous color names, which standardized the possible results.

The earliest sets of Ishihara plates, produced in 1916, were reserved exclusively for the army's use and featured Japanese characters within the diagrams. In 1917, in an effort to sell the series internationally, Ishihara redesigned it with the now-familiar Arabic numerals and published a set of 16 plates as Tests for Colour Deficiency.

The tests were adopted throughout the world beginning in the early 1920s, and eventually grew into a set of 38 plates. But their popularity almost led to their undoing. Unauthorized publishers printed their own version of the plates to meet demand, throwing the accuracy of the diagnostic colors into doubt. "The plates have been duplicated along with an easily memorized key by cheap color processes in the tabloid press, and exposed in public places, reducing the fifth edition [of the collection] to a parlor game," one psychologist warned in the Journal of the Optical Society of America in 1943.

Despite those obstacles, the tests proved indispensable for both practicing physicians and researchers. Ishihara continued to refine the designs and improve the color accuracy of the images into the late 1950s, while he also served as the chair of the ophthalmology department and then dean of the medical school at Tokyo Imperial University. In addition to Tests for Colour Deficiency, he also published an atlas, textbook, lectures, and research studies on eye diseases. But he is remembered most for the iconic charts that seamlessly blend art and science.


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