Regenerative medicine repairs mice from top to toe

At the turn of the twentieth century, the promise of regenerating damaged tissue was so far-fetched that Thomas Hunt Morgan, despairing that his work on earthworms could ever be applied to humans, abandoned the field to study heredity instead. Though he won the Nobel Prize in 1933 for his work on the role of chromosomes in inheritance, if he lived today, the advances in regenerative medicine may have tempted him to reconsider.

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.

Transplanting bioengineered stem cells into nude mice enabled them to grow hair.

Takashi Tsuji/Tokyo University of Science

You can grow cells in a Petri dish, but thats not regenerative medicine, says Robin Ali, a geneticist at University College London, who led the eye study. You have to think about the biology of repair in a living system.

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.

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 5weeks 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.

Mayumi Ito, a dermatologist at New York University, says that this is the first report to reconstitute hair follicles using human cells. But for the technique to be effective, the researchers need to show that they can expand the number of hair follicles that they are able to grow.

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 light2. 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 -transducin, a protein needed to see in dim light. Around 26,000 new rods were delivered into each eye, which normally contains 6 millionrods. Only 1015% of the rods integrated into the retina, but they still improved vision.

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Regenerative medicine repairs mice from top to toe