GENE therapy meets stem cells. That is the wave of the future, if the recent annual meeting of the American Society of Gene Therapy in Seattle is any guide. There was a palpable buzz around efforts to correct diseases by targeting therapeutic genes to stem cells already resident in the body.
Clinical trials are on the horizon for treatments for diabetes and a group of fatal neurodegenerative conditions called lysosomal storage diseases. Meanwhile, gene therapists are also using their skills to make "improved" stem cells for regenerative therapies (see "Stem cell enhancement"). "If you look at what is happening today and what is in the pipeline, I think genetic modification of stem cells is going to be a major theme," says Luigi Naldini of the San Raffaele Telethon Institute of Gene Therapy in Milan, Italy.
Stem cell enhancement
"People are excited about the potential of stem cells, but most approaches are not leveraging them to their maximum potential," says Madhusudan Peshwa of MaxCyte in Gaithersburg, Maryland. "We're not getting into the driving seat and getting the cells to do what we want them to do."
Many teams have attempted to use adult stem cells in regenerative medicine - to repair damaged tissue after a heart attack, for example -but their efforts have been hampered by problems such as cells dying before reaching their target or not differentiating into the correct cell type.
Now researchers are waking up to the idea of genetically modifying stem cells to enhance their natural attributes and gain a new level of control over them. In the case of heart attacks, stem cells from both skeletal muscle and bone marrow have been shown to repair tissue damage to some degree, either through differentiating into heart muscle cells or releasing chemicals that stimulate existing cells to repair the damage. To make this process more effective, Marc Penn at the Center for Stem Cell and Regenerative Medicine in Cleveland, Ohio, genetically engineered bone marrow stem cells to produce triple the normal amount of a signalling factor called SDF-1. This is an "SOS signal" also released by damaged heart cells after an attack and is thought to recruit repair cells to the damaged area.
"The idea is to try and restart natural signals that initiate repair," says Penn. When the cells were injected into rats' hearts after a heart attack, the team saw a 70 per cent reduction in heart cell death, compared with rats given unmodified stem cells (The FASEB Journal, DOI: 10.1096/fj.06-6558com).
Tags: Stem Cells, Gene Therapy, Madhusudan Peshwa, SDF-1, Type 1
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