"It’s been proven that all humans lose stem cells as we age. These adult stem cells reside in “niches” in our organs and bone marrow, and are responsible for replenishing dead cells and growing new ones. We need stem cells to grow hair, maintain organs, and heal wounds. All of this slows down as we age and our stem cell reserves are depleted. But there’s one type of adult stem cell that serves as a “master regulator” of all other stem cells, Hare explained. Mesenchymal stem cells, which are found all over the body, including the lining of blood vessels, orchestrate the replenishing activity in tissue, organs, and bone marrow. Hare’s hypothesis was that by boosting the supply of these master stem cells in older people, it could replenish stem cells across the body and combat the symptoms of frailty."