Scientists from A*STAR's Institute of Medical Biology (IMB) in Singapore and the University of Hong Kong's Department of Medicine have produced the world's first human cell model of progeria, a disease resulting in severe premature ageing in one in four to eight million children worldwide. This model has allowed them to make new discoveries concerning the mechanism by which progeria works. Their findings were published this month in the prestigious scientific journal, Cell Stem Cell (1).
Hutchinson-Gilford Progeria Syndrome, also known as progeria, is caused by a mutation in the gene encoding for the protein lamin A, an important component of the membrane surrounding a cell's nucleus. The mutation results in a truncated form of lamin A called progerin, which in turn causes misshapen cell nuclei and DNA damage. Children with progeria suffer symptoms of premature ageing, including growth retardation, baldness, and atherosclerosis (hardened arteries), and all die in their early teens from either heart attack or stroke.
Led by IMB's Profs Alan Colman and Colin Stewart, the team used a novel technique of deriving induced pluripotent stem (iPS) cells from cells of human progeria patients . This human progeria model allows the group to trace and analyse the distinctive characteristics of progeria as it progresses in human cells. Previously, only mouse models of the disease were available.
Said Prof Colman, "While mouse models of progeria have been informative, no one mouse model recapitulates all the symptoms seen in humans. Our human progeria model allows us to examine the pathology of the disease at a much closer resolution than previously possible."
The researchers used their iPS cells to identify two types of cells - mesenchymal stem cells (MSCs) and vascular smooth muscle cells (VSMCs) – that were particularly adversely affected by progeria. This means that a young patient with progeria would typically have fewer MSCs and VSMCs than other children. MSCs were found to be very sensitive to a low oxygen environment and their losses could delay renewal of the various tissues they gave rise to, thus exacerbating the patient's symptoms of ageing. The same effect on VSMCs could explain why their number was reduced in the patient's heart vessels.
Background
The group's findings are a significant boost to existing research on over 10 diseases associated with lamin gene mutations. Prof Stewart previously led a study in mice at IMB showing that progeria affected the connective tissues, potentially via defects in a signaling pathway connecting the nuclear lamina with the extracellular matrix (2) and which was associated with death of the smooth muscle in major blood vessels.
Said Prof Stewart, "This new study provides further evidence for the role of lamin processing in connective tissue function, as well as insights into the normal ageing process. We hope to soon find new routes of intervention to treat this incurable disease. Such interventions may be of use in treating atherosclerosis in general, a condition afflicting many millions of individuals."
References: (1) A Human iPSC Model of Hutchinson Gilford Progeria Reveals Vascular Smooth Muscle and Mesenchymal Stem Cell Defects. 7 Jan 2011. Cell Stem Cell, Volume x, Issue y. DOI: 10.1016/j.stem.2010.12.002
(2) Functional Coupling between the Extracellular Matrix and Nuclear Lamina by Wnt Signaling in Progeria. Developmental Cell, 2010; 19 (3): 413-425 DOI: 10.1016/j.devcel.2010.08.013
About the Institute of Medical Biology (IMB)
IMB is a member of the Agency for Science, Technology and Research (A*STAR). With its roots in the Centre for Molecular Medicine since 2004, it became the Institute of Medical Biology in 2007, with a mission to study mechanisms of human disease in order to discover new and effective therapeutic strategies for improved quality of life.
IMB is developing internationally excellent research programmes working closely with clinical collaborators, targeting the challenging interface between basic science and clinical medicine, and aiming to promote increased and effective throughput of research from bench to bedside. Its growing portfolio of strategic research topics aims to promote translational research on the mechanisms of human diseases with a cell to tissue emphasis that can help identify new therapeutic strategies for disease amelioration, cure and eradication.
For more information about IMB, please visit www.imb.a-star.edu.sg.
About the Agency for Science, Technology and Research (A*STAR)
The Agency for Science, Technology and Research (A*STAR) is the lead agency for fostering world-class scientific research and talent for a vibrant knowledge-based and innovation-driven Singapore. A*STAR oversees 14 biomedical sciences and physical sciences and engineering research institutes, and nine consortia & centres, located in Biopolis and Fusionopolis as well as their immediate vicinity.
A*STAR supports Singapore's key economic clusters by providing intellectual, human and industrial capital to its partners in industry. It also supports extramural research in the universities, hospitals, research centres, and with other local and international partners.
For more information about A*STAR, please visit www.a-star.edu.sg.
Journal
Cell Stem Cell