Researchers at the Wellman Center for Photomedicine at Massachusetts General Hospital (MGH; Boston, MA) have found that low-level laser therapy may offer a noninvasive, drug-free treatment for thrombocytopenia—a potentially life-threatening shortage of the platelets (blood cells) that are essential to blood clotting. Low-level laser therapy increased the generation of platelets from precursor cells called megakaryocytes (MKs) and had the same effect in several mouse models of the condition. They also identified the probable mechanism underlying this effect.
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Low-level lasers, sometimes called cold lasers, emit low-power laser light that does not heat its target tissue. The therapy has been used to improve wound healing, relieve pain, and treat conditions such as stroke and neurodegenerative disorders. It is known to protect the function of mitochondria (cellular structures that provide cells with energy), and several conditions associated with impaired platelet production are characterized by abnormalities in mitochondria of the bone marrow cells that give rise to platelets.
The body responds to low platelet levels by rapid differentiation of MKs from hematopoietic stem cells and an exponential increase in the number of the cells. MKs expand in size, along with with many rounds of DNA replication without cellular division, which results in giant cells containing multiple copies of each chromosome—a condition called polyploidy—instead of the two copies found in most cells. Each of these giant, polyploid MKs generates many long, branched, small tubular structures called proplatelets that eventually fragment into thousands of platelets.
The research team conducted a number of experiments to investigate whether low-level laser therapy's ability to protect mitochondrial function could mitigate several forms of thrombocytopenia. Mei X. Wu, Ph.D., the senior author of the study, notes that low-level laser therapy's lack of an effect in animals without thrombocytopenia indicates it would probably avoid the potential complications of current drug treatments, which act by increasing the production of MKs from their progenitors in the bone marrow. Because the treatment only has an effect in polyploid cells, which are very rare, it implies that it would not increase production of mitochondrial in cancer cells or other cells, Wu adds.
The current primary obstacle to testing low-level laser therapy in human patients is the lack of a device large enough to treat either the entire body or enough bones to stimulate sufficient platelet production by MKs within the bone marrow—something Wu and her team plans to address. She also adds that, while low-level laser therapy will probably be beneficial for treatment of many forms of acquired thrombocytopenia, it may not be effective when the condition is caused by inborn genetic defects.
Full details of the work appear in the journal Science Translational Medicine; for more information, please visit http://dx.doi.org/10.1126/scitranslmed.aaf4964.