Nature – Three studies published this week show that introducing new cells into mice can replace diseased cells — whether hair, eye or heart — and help to restore the normal function of those cells. These proof-of-principle studies now have researchers setting their sights on clinical trials to see if the procedures could work in humans.
In work published in Nature Communications, Japanese researchers grew different types of hair on nude mice, using stem cells from normal mice and balding humans to recreate the follicles from which hair normally emerges1. Takashi Tsuji, a regenerative-medicine specialist at Tokyo University of Science who led the study, says that the technique holds promise for treating male pattern baldness.
Transplanting bioengineered stem cells into nude mice enabled them to grow hair. Takashi Tsuji/Tokyo University of Science
The team used a specialized nylon sheath to guide the hair through the skin layers, enabling it to erupt from the skin of the mice in 94% of all grafts. The hairs took between 2 and 5 weeks to emerge, and behaved as normal: they underwent normal growth cycles and established connections to the muscles and nerves underneath the skin. The hairs also lifted up from the skin in response to acetylcholine, a neurotransmitter known to cause hairs to stand on end.
A second study using regenerative techniques helped to restore some vision to mice with congenital stationary night blindness, an inherited disease of the retina — the part of the eye that is sensitive to light 2. The research, published in Nature, could potentially be used for treating macular degeneration, which causes damage to the retina.
Ali and his colleagues transplanted precursor rod cells, which have a role in night-time vision, into the retinas of mice lacking α-transducin, a protein needed to see in dim light. Around 26,000 new rods were delivered into each eye, which normally contains 6 million rods. Only 10–15% of the rods integrated into the retina, but they still improved vision.
Deepak Srivastava, director of the UCSF Gladstone Institute of Cardiovascular Disease, led a team in reprogramming cardiac fibroblasts into cardiomyocytes — the muscle cells of the heart that are permanently lost after a heart attack. The team used a retrovirus to deliver three transcription factors that induced the reprogramming in adult mice, and improved their cardiac function. This study follows on from work in 2003, when Srivastava and his colleagues discovered that a mutation in one of these transcription factors, GATA4, caused heart disease in several generations of a family under his care4. “What I do clinically, motivates me. Absolutely, every day,” he says.