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article imageBone Repair Using Patient's Stem Cells A Step Closer

By Bob Ewing     May 26, 2008 in Science
Researchers at the University of Twente show that if the enzyme PKA is previously activated in the stem cells in the lab, it can result in substantial bone formation.
Researchers at the University of Twente have demonstrated that if the enzyme PKA is previously activated in the stem cells in the lab, following implantation this results in substantial bone formation. This opens up new ways of repairing bone tissue using cell material from the patient. The researchers are publishing their work in the Proceedings of the National Academy of Sciences (PNAS).
‘Adult’ mesenchymal stem cells have already been used successfully in animals to grow fresh bone.
There has been less success when it comes to bone formation using human adult stem cells, e.g. from bone marrow. This has hitherto limited the alternatives hospitals can offer for repairing damaged tissue other than spontaneous healing.
When the PKA enzyme is activated prior to implantation, however, this produces a dramatic improvement in ‘in vivo’ bone growth. The cells can be observed maturing into bone cells already in the lab; once sown on a carrier and implanted in a mouse, the bone grows well.
The enzyme protein kinase A (PKA) is responsible for many processes in a cell. The messenger ‘cyclic AMP’ activates PKA: the researchers think that adding it to the stem cells ensures that they stimulate one another.
Cyclic AMP promotes maturation into bone cells and the cells themselves also secrete various substances that stimulate bone growth. This may explain why mesenchymal stem cells treated with cyclic AMP form significantly more bone than those without the stimulus.
The advantage of administering a bone-growth-stimulating substance in advance is that it can be removed just before implantation. Prior experiments have mainly used high concentrations of a bone-growth-stimulating hormone, e.g. incorporated in the carrier on which the cells are ‘sown’.
Now, not only are the hormone concentrations lower, but they also more closely resembling the cocktail of hormones normally involved in bone growth.
This is the second time in a short space of time that the researchers, led by Dr Jan de Boer, have published in PNAS: earlier this month they published an article on a major breakthrough in the use of embryonic stem cells to grow bone.
Both of the methods show promise when it comes to repairing bone tissue in future using cells from the patient’s own body. Compact bioreactors will be developed to grow cells quickly into tissue that can be used in the operating theatre.
The research was carried out at the Tissue Regeneration Department of the University of Twente’s Institute for Biomechanical Technology (BMTI). The researchers collaborated with fellow scientists at UMC Utrecht and the Erasmus Medical Center in Rotterdam.
More about Stem cells, Bone, Disease
 
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