Kang Kyung-sun
Seoul National University researcher |
By Kim Tong-hyung
Scientists have added detail to the complex picture related to the aging of adult stem cells, which they claim may prove to be a breakthrough in developing therapies based on stem cells taken from patients.
Stem cells, or early-stage cells that retain the potential to turn into other specialized types of cells, are intriguing for their immense potential in treating a wide range of difficult diseases and conditions.
And holding an important key to such innovations would be adult stem cells, which are taken from mature tissue, as they could theoretically be taken from patients, grown in culture and transplanted back into the patient without the fear of provoking an immune response.
Adult stem cells also carry the hopes of scientists to find a way out of the bitter ethnical debate related to embryonic stem cell research, as they are sourced from adult cells rather than human embryos.
The downside of adult stem cells, however, is that they age much faster than embryonic cells, which has limited their usefulness in transplants.
In a series of studies recently published by Cellular and Molecular Life Science, researchers led by Seoul National University’s (SNU) Kang Kyung-sun reported some new findings related to the premature aging of adult stem cells, which they say improves the explanation on what makes humans grow old as well.
It has been presumed that the decreasing regenerative capacity of adult stem cells, which is linked to their aging, is a result of inborn genetic variations. But Kang suggests that the process isn’t dictated by heritable events, such as DNA damage, but rather determined by an “epigenetic” regulation of gene expression.
Epigenetic mechanisms refer to the changes in cell control that involve genes being switched on or off, which determines what parts of a person’s DNA is expressed and how. This hidden influence, which adds a whole new layer to genes beyond inherited DNA, is believed to be connected to how cells of particular body parts and organs acquire their specific functions.
According to Kang and his colleagues, the aging of adult stem cells has much to do with the roles played out by particular proteins, including the polycomb-group of genes and jumonji domain containing 3 (JMJD3), which are known for their connection to the acetylation of the histone protein. The down-regulation of polycomb-group genes, such as BMI1, EZH2 and SUZ12, and up-regulation of JMJD3, were observed in aged adult stem cells, according to Kang.
Kang’s colleagues also identified three micro-RNAs that inhibit the high mobility group A2 (HMGA2) gene, which accelerates the process of the adult cell’s aging. Micro-RNAs are tiny pieces of genetic material that target and suppress the activities of other genes.
“There weren’t many studies on finding micro-RNAs related to the aging of cells and learn how they affect stem cells, but this area could be important in developing a way to have adult stem cells retain their normal ability for a longer time,” Kang said.
“The studies on micro-RNAs will also be important in improving the studies on how humans age, as the decline in the regenerative functions of stem cells basically explains how we grow old.
줄기세포노화 문제해결 ‘청신호’
성체줄기세포를 질병치료에 이용하는데 최대 난점으로 꼽혀 온 `조기노화' 문제가 해결될 수 있을지 관심을 모으고 있다.
성체 줄기세포는 이론적으로 환자들로부터 채취될 수 있고 초기 줄기세포 연구에 쓰일 수도 있다. 하지만 초기 줄기세포보다 너무 빨리 늙는 탓에 이식방면에 유용하게 쓸 수 없었다.
하지만 이번 서울대 강경선교수 연구팀이 성체줄기세포의 빠른 노화에 대한 연구를 결과를 발표했다.
연구팀에 의하면 성체줄기 노화는 일부 특정한 단백질의 역할 때문에 일어난다.
강교수는 “아직 Micro-RNA와 성체줄기세포 노화의 관계와 줄기세포에 어떤 영향 주는지 규명하진 못했다”며 “Micro-RNA 연구가 왜 사람이 늙는지를 설명 해줄 아주 중요한 요소다”고 말했다.
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