Platelets, formed in mammalian blood. Excessively active platelets can also cause a variety of diseases, including severe blood clots, heart disease and cancer.
How to prevent platelets from "negative"? On February 13th, an article in the journal Science Translational Medicine gave the answer: Scientists “improved” platelets, made into platelet decoys, which are effective in preventing thrombosis and possibly preventing cancer. Transfer.
“Reversibility and immediate onset are the main advantages of our platelets & lsquo;bait & rsquo; we think they can be used clinically. "The first author of the study, Dr. Anne-Laure Papa, said that this treatment can prevent high-risk patients from developing blood clots before surgery, or concurrently with cancer to prevent cancer from spreading." ”
Normal platelets (left) and platelet decoys (right) were compared side by side under a microscope. Image source: A. -L. Papa et al., Science Translational Medicine (2018)
Bait platelet antithrombotic
In this study, the treatment used a deactivated “bait” platelet, which is characterized in that it still binds to some cells but does not aggregate or achieve other normal platelet functions, including chemical signals associated with the coagulation process. Conduction.
To create "bait" platelets, the team used natural platelets as a material, detergent treatment and centrifugation to remove its internal structure and its basic activation and aggregation capabilities. These "bait" platelets are about one-third the size of conventional platelets, while retaining most of the adherent receptors on their surface. This allows them to bind to other cells in the bloodstream, such as cancer cells, but does not become active during blood coagulation.
When platelets are activated, they emit long tendrils and gather together to form a blood clot (left). When the baits are exposed to the same platelet-stimulating molecules, they cannot activate and maintain their circular "stationary" shape (right). Image source: Harvard University Weiss College
Studies have shown that when "bait" platelets are infused into microfluidics (vascular simulation devices), the bait does not exhibit typical clotting behavior of platelets. Moreover, by adding the bait to normal blood, the aggregation and coagulation ability of normal platelets is weakened.
“‘Beaker & rsquo;Different from normal intact platelets,"An image of Dr. Anne-Laure Papa's image, "Imagine, & lsquo; Bait & rsquo; is a fast-moving skater sliding along the wall. An ice rink, their high speed prevents other skaters from entering the wall, limiting their slowing down and catching it. ”
More importantly, scientists have found that by adding fresh platelets to the channel, it is possible to quickly reverse the inhibition of normal platelet activity by "bait" Intravenous injection of platelets into patients is a common medical treatment in hospitals. As a result, patients with platelets who need to quickly recover from thrombosis after injury or surgery can be treated easily in a short period of time. Most importantly, "bait" can also be produced from platelets taken from the same patient to provide a personalized cell therapy that does not elicit an immune response.
"Beaker"; platelets or prevent tumor metastasis
Known studies have shown that platelets bind to cancer cells, protecting them from the body's immune system, helping them form new metastatic tumors at a distance.
When the team infused normal platelets and human breast cancer cells into microfluidic channels, the cancer cells adhered and began to invade the channel walls, similar to their behavior in forming new tumors. Surprisingly, adding "bait" platelets can prevent platelets from helping cancer cells invade the walls of the channel, suggesting that they can prevent the formation of new tumors.
To confirm this potential, the researchers injected mice with human platelets or a combination of platelets and baits, and then injected human breast cancer cells. The results of the study showed that mice receiving platelet plus bait had smaller tumor tissue and fewer metastatic tumors than mice receiving normal platelets.
Although this study has not been tested in humans, in the future these baits may be injected into patients during chemotherapy to prevent the spread of existing tumors or to be injected during cancer surgery to prevent the release of tumor cells in other parts of the body. Form new tumors.
Researchers will continue to study this technology to ensure that "bait" can last longer in the blood to increase efficiency. They also want to study whether platelets "bait" can be loaded with drugs and sent directly to the thrombus and tumor sites, and may even kill circulating tumor cells in the blood.