Roughly 20 years ago, a biologist named Caroline Gargett went in search of some remarkable cells in tissue that had been removed during hysterectomy surgeries. The cells came from the endometrium, which lines the inside of the uterus. When Dr. Gargett cultured the cells in a petri dish, they looked like round clumps surrounded by a clear, pink medium. But examining them with a microscope, she saw what she was looking for — two kinds of cells, one flat and roundish, the other elongated and tapered, with whisker-like protrusions.
Dr. Gargett strongly suspected that the cells were adult stem cells — rare, self-renewing cells, some of which can give rise to many different types of tissues. She and other researchers had long hypothesised that the endometrium contained stem cells, given its remarkable capacity to regrow itself each month. The tissue, which provides a site for an embryo to implant during pregnancy and is shed during menstruation, undergoes roughly 400 rounds of shedding and regrowth before a woman reaches menopause. But although scientists had isolated adult stem cells from many other regenerating tissues — including bone marrow, the heart, and muscle — “no one had identified adult stem cells in endometrium,” Dr. Gargett says.
