Mice bred to age too quickly seemed to have sipped from the fountain of youth after scientists injected them with stem cell-like progenitor cells derived from the muscle of young, healthy animals.
Instead of becoming infirm and dying early as untreated mice did, animals that got the stem/progenitor cells improved their health and lived two to three times longer than expected.
The findings by scientists at the University of Pittsburgh School of Medicine were published in the Jan. 3 edition of Nature Communications.
Previous research has revealed stem cell dysfunction, such as poor replication and differentiation, in a variety of tissues in old age, but it's not been clear whether that loss of function contributed to the aging process or was a result of it, explained senior investigators Johnny Huard and Laura Niedernhofer,
"Our experiments showed that mice that have progeria, a disorder of premature aging, were healthier and lived longer after an injection of stem cells from young, healthy animals," Niedernhofer said. "That tells us that stem cell dysfunction is a cause of the changes we see with aging."
Their team examined a stem/progenitor cell population derived from the muscle of progeria mice and found that compared to those from normal rodents, the cells were fewer in number, did not replicate as often, didn't differentiate as readily into specialized cells and were impaired in their ability to regenerate damaged muscle. The same defects were discovered in the stem/progenitor cells isolated from very old mice.
"We wanted to see if we could rescue these rapidly aging animals, so we injected stem/progenitor cells from young, healthy mice into the abdomens of 17-day-old progeria mice," Dr. Huard said. "Typically the progeria mice die at around 21 to 28 days of age, but the treated animals lived far longer – some even lived beyond 66 days. They also were in better general health."
As the progeria mice age, they lose muscle mass in their hind limbs, hunch over, tremble, and move slowly and awkwardly. Affected mice that got a shot of stem cells just before showing the first signs of aging were more like normal mice, and they grew almost as large. Closer examination showed new blood vessel growth in the brain and muscle, even though the stem/progenitor cells weren't detected in those tissues.
In fact, the cells didn't migrate to any particular tissue after injection into the abdomen.
"This leads us to think that healthy cells secrete factors to create an environment that help correct the dysfunction present in the native stem cell population and aged tissue," Dr. Niedernhofer said. "In a culture dish experiment, we put young stem cells close to, but not touching, progeria stem cells, and the unhealthy cells functionally improved."
Animals that age normally were not treated with stem/progenitor cells, but the provocative findings urge further research, she added. They hint that it might be possible one day to forestall the biological declines associated with aging by delivering a shot of youthful vigor, particularly if specific rejuvenating proteins or molecules produced by the stem cells could be identified and isolated.
"줄기세포로 쥐 노화 늦췄다"
노화하는 신체에 젊은 세포를 주입하면 신체가 튼튼해지고 생명이 연장될 가능성이 있다는 연구 결과가 나왔다고 ABC방송 인터넷판이 3일(현지시간) 보도했다.
보도에 따르면 피츠버그대 메디컬 센터 연구진은 빠르게 늙도록 유전적으로 변 형된 쥐들에 젊고 건강한 쥐에서 추출한 줄기세포로 보이는 세포들을 주사했다.
이들 세포는 노화 과정을 뒤집은 것으로 나타났다. 주사를 맞은 쥐들은 예상된 28일보다 긴 66일까지 살았다. 또 세포를 주사한 결과 근력 강화와 뇌 혈류에 도움을 준 것으로 나타났다.
이날 과학저널 '네이처 커뮤니케이션스'에 실린 논문의 공동 저자인 로라 니던 호퍼 박사는 "젊은 줄기세포들이 상당히 이로운 무언가의 비밀을 쥔 것으로 보인다"면서 "그것이 뭔지는 확실히 알 수 없다"고 말했다.
인간의 노화에 대처하는 연구는 노령 인구가 늘어나고 노인 관련 의료비가 증가 하는 가운데 중요성이 크다. 과학자들은 이미 인간의 세포를 가지고 치료하는 방법 을 연구하고 있다.
니던호퍼 박사는 이번 연구 결과가 앞으로의 연구에서 활용할 귀중한 실마리를 줬다고 말했다.
그러나 쥐를 상대로 한 실험이 성공했다고 인간의 노화를 막을 것으로 기대할 수는 없다는 지적이 있다고 ABC는 전했다.
줄기세포 전공인 하버드대 에이미 와거스 교수는 이번 결과를 인간의 노화에 적 용하는 것은 신중해야 한다고 말했다. 이번 실험에 사용된 쥐들은 선천성 조로증이 있어 보통의 쥐와도 다르다는 것이다. (연합뉴스)