Shining a little light on bone marrow cells may be the key to curing a common blood disorder involving low blood platelet count. Low blood platelets can cause serious health complications, such as uncontrollable bleeding and even death. This condition, known as thrombocytopenia, can occur as a result of genetic or immune diseases, cancer treatment, and even too much alcohol. Treatment for it often requires medications that come with side effects, and possibly blood transfusions. Now, researchers at Harvard Medical School and Massachusetts General Hospital have had breakthrough success treating this disorder in mice using a simple near-infrared, noninvasive laser treatment. Their results were recently published in Science.

Harvard researchers Qi Zhang, Mei Wu, and their colleagues tested a theory that a low-level laser (LLL) treatment, currently used in clinical settings for pain relief, wound healing, and even hair regrowth, would also work to stimulate platelet production. It's sometimes called cold laser therapy because the light doesn't heat its target. “One of [the] major uses of low-level light is to improve mitochondrial function,” Mei Wu, associate professor of photomedicine in the department of dermatology at Harvard, tells mental_floss.

Mitochondrial function is key in platelet production. The cells that produce blood platelets, known as megakaryocytes, must first “enlarge 10 times bigger than other cells,” Wu says, because “the cell undergoes multiple rounds of DNA replication [in order] to enlarge.” These cells need very high levels of ATP, the essential energy that drives the mitochondria of all cells. She adds, “The energy is very important. ATP determines how many platelets you produce for each megakaryocyte.”

They tested the laser treatment on mice they had irradiated to induce low platelet counts. “We put the animals under the laser for five minutes, and we saw the platelets recover very quickly compared to the controls,” Wu says. They were astonished by the results: The treatment doubled the number of platelets in the mice, and it cut the recovery time from radiation from five days to just two. 

Even better, the LLL treatment had no negative side effects on healthy mice. Wu explains, “The beauty of [the] laser is it only works if you have low platelets. But if your platelets are normal, you won’t see any side effects.”

Wu says she is often asked why regular sunlight doesn’t have the same effect on increasing low platelet counts, to which she gives an analogy. “If a sick person needs oxygen, they need pure, condensed oxygen. The laser is similar. Sunlight is not highly concentrated. You need highly concentrated light [to increase platelets] so the effect is very specific and you don’t see that with sunlight.”

The treatment possibilities are very exciting to the researchers, but in order to take it to human clinical trials, they will have to design a bigger machine. “[Existing] lasers can only shine on small spots on the skin," Wu explains. "In order for this new modality to be effective in humans, we need a new low-level device that can shine [on] the whole body, or most of it, because megakaryocytes are located in the bones. There is no machine that can shine on the whole body.”

The design for that machine, Wu says, is under way.