ShareThisBeyond the debate over the relative value of research involving stems cells from embryos or adults, scientists are increasingly finding that when it comes to repairing or replacing bone or muscle tissue, different cells can yield a wide array of results.
One study published last month by Harvard researchers working with mouse and rat cells found that even mature heart-muscle cells can be coaxed back into a cycle of regeneration.
It had long been thought that what you got in the way of heart muscle as an infant was all you would get -- the growth pretty much stopped in prenatal development, and humans and all other animals with hearts have to live with the loss of those cells on through life.
More recently, scientists have learned that adult heart-muscle cells replace themselves at a slow rate, with perhaps half of the cells in a heart turning over during a lifetime. That still meant that major damage to a heart needed outside help, such as injections of cultured heart-muscle cells into damaged areas.
But the Harvard study found that several chemical signals, including one growth factor called neuregulin 1, or NRG1, can ramp up the repair activity in heart cells to a much faster pace in animals.
Injecting the growth factor in adult mice was shown to boost the cell-rejuvenation process and produced regenerated heart muscle that led to improved function after the animals suffered a heart attack.
A lot more testing needs to be done, particularly to make sure the cells don't over-proliferate, but scientists envision a time not too far off when people with damaged hearts might get injections of NRG1 over several weeks and come away with the organ regenerated from within.
Meanwhile, researchers at the Imperial College in London reported some success at customizing bone regrowth from different types of cells.
Specifically, they reported in a recent issue of Nature Materials that they used a laser-based form of spectroscopy to analyze the chemical makeup of bone cells taken from the skulls and marrow of adult mice as well as embryonic stem cells.
While each type of cell line is able to grow nodules of "bone-like material,'' the quality of the output was very different in terms of mineral composition and physical properties.
Bony material derived from skull and marrow cells was much more like real bone in terms of density and stiffness. The material from embryonic cells was much less stiff and less complex.
A number of clinical trials are already under way using all three types of materials to grow replacement bones for people who have lost bones or parts of bones to surgery or accidents. Any techniques are still some years from being used widely in human patients.
"This tells us a lot about how using different cell sources can influence the quality of bone that we can produce," said Molly Stevens, a biomedical engineer at the college who led the study. "It brings us one step closer to developing materials that will have the highest chances of success when implanted into patients."
(Contact Lee Bowman at bowmanL(at)shns.com)
Medical Journal
