In an effort to begin to see if what they have seen in laboratory mice holds up in humans, they are trying both approaches in human stem cells retrieved during the process of a knee or hip replacement by colleagues in the MCG Department of Orthopaedic Surgery. So they also are taking more direct approaches like whether an IDO inhibitor – which is already in clinical trials as a cancer fighter – can reverse changes and get stem cells to regain more youthful function. Isales notes that they may find that other amino acids produce similar problems as tryptophan in the aged environment. Over time, kynurenine piles up and appears to alter the dynamic of bone and muscle formation.Īgain, somewhat ironically, the many functions of essential amino acids include working as antioxidants, so the researchers are putting together nutrient cocktails – minus tryptophan and with reduced protein content – that they hope can reverse age-related damage. Kynurenine results when the enzyme, indoleamine 2,3 dioxygenase, or IDO, which a variety of tissues make to help moderate an immune response, oxidizes tryptophan.
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Particularly with age, the free radicals produced by oxidation can also damage cells. The unhealthy metabolite is the result of a natural action called oxidation, which occurs anytime cells use oxygen. The researchers also think the fuel sends signals to cells, ones that aging stem cells apparently don’t get. Tryptophan is among the nine amino acids our body can’t make and we must consume in foods like turkey and soybeans so we can perform essentials like making protein. Much as the function of bone and muscle is interwoven, so is their health and the factors that promote their loss or survival also are similar, said Hamrick.Ī major culprit in their breakdown appears to be the metabolite kynurenine, a byproduct of the essential amino acid tryptophan. “We are trying to figure out why the changes are happening and if we can target those cells to make them want to make bone again,” McGee-Lawrence said. The other thing we are looking at is their survival and their numbers.”
“This includes a loss of direction so they aren’t as functional as they were before. “We are looking at stem cells as a group and what is happening to them as we age,” Hill noted. Meghan McGee-Lawrence, wants to keep stem cells focused on making bone and muscle. The team, which includes principal investigators bone biologist Dr. The bottom line: Our stem cell population gets reduced and the cells we have become less efficient at making bone and muscle, often opting for the easier task of making fat instead, Isales said. The MCG scientists also have evidence it changes the signals stem cells send each other. Time seems to alter the dynamic between the mesenchymal stem cells making bone and muscle and the amino acids that fuel them. But what we are focusing on is trying to see if we can flatten the curve even further,” said Isales, principal investigator on a new $9.3 million Program Project grant from the National Institutes of Health. “Daily exercise decreases the slope of that decline. Carlos Isales, endocrinologist, Regents’ Professor and vice chair for clinical affairs in the MCG Department of Neuroscience and Regenerative Medicine. “After age 65 you start losing about 1 percent of both muscle and bone per year,” said Dr. The world’s older population is growing at an unprecedented rate with 8.5 percent of the worldwide population – 617 million people – age 65 and older, a proportion estimated to reach 17 percent by 2050, according to the National Institute on Aging.
Osteoporosis already is a major public health problem affecting about 44 million Americans and costing billions annually. Now researchers at the Medical College of Georgia at Augusta University are dissecting just what happens to the stem cells that make the tissues, which help keep us upright, with an eye on improving our healthspan. AUGUSTA, Ga. – With age, the form and function of our bones and muscles drop off, putting us as increased risk for frailty and falls.
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