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Projet ERISTO |
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Project mainly funded by the European Space Agency
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For millions of years, evolution has fashioned the skeleton of vertebrates to best adapt it to the gravity forces.
On earth, specific situations such as immobilization or bed rest lower the gravity effects on the body. In space, during space flights, the astronaut skeleton is no longer subjected to the gravity forces and has to readapt very quickly to this new environment. In both situations, abnormal bone loss occurs. In the case of astronauts, this bone loss is rapid and can reach up to one per cent of bone mass per month mainly in the weight bearing bones. This remains a major physiological problem to solve for very long duration space flights.
ERISTO is an international project, which is part of the European Space Agency Microgravity Application Program. The project is focused on the effects of mechanical stress on bone remodeling, space environment providing access to unique "stress free" experimental conditions. ERISTO links medical research and the search for prevention of serious osteoporotic bone diseases with the unique benefit of space, which provides an accelerated model of bone loss.
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1999 - Mission Perseus. Even in case of high work load, the normally weight-bearing bones are only very lightly loaded (Courtesy CNES)
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Bone is a living organ, which is normally maintained in a healthy condition by constant replacement at a rate of 3 -5 % per year. This natural and essential lifelong process is called "remodeling". Its porous structure is adapted to resist to mechanical constraints with a minimum mass.
Bone has a permanent remodeling activity. This remodeling is controlled locally, mainly by two antagonistic cellular activities, bone resorption by osteoclasts, and bone formation by osteoblasts. Bone formation can be activated by mechanical stress on the cells. This process could explain that the incidence of osteoporosis is increasing with both aging and sedentary lifestyle.
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Click on the image to see the corresponding film... You must have an MPEG player (Courtesy Millenium)
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Bone Resorption by osteoclasts (Courtesy LBBTO, L. Vico, C. Alexandre and MH Lafage-Proust)
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Bone Formation by osteoblasts(Courtesy LBBTO, L. Vico, C. Alexandre and MH Lafage-Proust)
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Osteoporosis is a disease leading to a weakening of the bones. This silent disease often results in a fracture without any precursor symptom. Along with population aging and the increasing impact of sedentary lifestyle, more and more epidemiological studies show that osteoporosis, the unbearable silent disease, has become a public health priority.
According to the figures provided by the World Health Organization in October 2001: A fracture from osteoporosis occurs every 30 seconds in the European Union. The disease affects 20 to 30% of postmenopausal women, 50% of women over 60 years old, and 13% of men over 50 years old, the fracture risk increasing sharply with age. Osteoporosis is the second most important public health problem for women after breast cancer. The induced hospital costs are estimated to 23 Billion Euros per year and the number of hip fractures, estimated to nearly 400 000, is estimated to reach one million within 50 years.
The main risk factors are genetic, hormonal and related to sedentary lifestyle and the related lack of physical activity.
For osteoporosis, astronauts can be considered as "hyper-sedentary" persons: the bone loss observed after a space flight of a few months corresponds to that of several years on ground.
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Osteoporosis: The silent Disease - Evolution of the bone mass according to the age (Courtesy Millenium, S. Pugh)
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Designing innovative diagnostic and preventive tools is a major objective in osteoporosis research. The ERISTO project, funded by the European Space Agency, the national space agencies, by the partners and by industrials, addresses key research issues on biological effects of mechanical constraints on bone cells, bone remodeling and quality.
ERISTO develops in vitro 3D3C models mimicking real bone remodelling in 3 dimensions. These models will enable to partly replace the need for experiments on animals and humans.
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Observation in Vivo of the mineralization edge(Courtesy LBBTO, L. Vico, C. Alexandre and MH Lafage-Proust)
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Same observation In-Vitro (Courtesy D. Jones). Such bone formation in-Vitro can only be obtained when mimicking mechanical loading close to organotypical values
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Space experiments are planned to validate ERISTO models in "mechanically stress free" conditions.
New methods to evaluate In Vivo bone micro-architecture have been validated. These methods allow imaging of bone 3D microarchitecture and finite element analysis to calculate bone mechanical properties.
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3D Micro Architecture of a rat vertebrae observed with 3D Micro Computed Tomograph. This film is not an image synthesis but a real 3D picture reconstituted by computer anlalysis based on the scanning data (Courtesy Scanco Medical and P. Regsegger).
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The ERISTO project is carried out by several international groups combining industry and research from both the biomedical and the space sectors. As a result of the collaboration, the Canadian Millennium Company, partner of ERISTO, created a subsidiary in Europe.
ERISTO is developing promising applications with the important support of space such as new research models on osteoporosis, new products like resorbable biomaterials which could be used as artificial bones. This research should improve the diagnosis, the prevention and the treatment of this disease.
More about ERISTO... Click on the ERISTO section on the left menu.
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Bone-like Synthetic 3D Scaffolds for Research and Clinical applications. One of the criteria for bone matrices is to achieve bone structural similarity. (Courtesy Millenium Biologix, S. Pugh)
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