Stories about: platelets

The platelet whisperers

Finding the switch that gets megakaryocytes to produce platelets
To manufacture platelets in the laboratory, we need to find the switch that starts their production.
Looking down at my bandaged finger—a souvenir of a kitchen accident a few nights prior—Joseph Italiano, PhD, smiles and says to me, “You should have come by, we could’ve given you some platelets for that.”

The problem is that Italiano really couldn’t; he needs every platelet his lab can put its hands on. A platelet biologist in Boston Children’s Hospital’s Vascular Biology Program, Italiano is trying to find ways to manufacture platelets at a clinically useful scale.

To do that, he needs to develop a deep understanding of the science of how the body produces platelets, something that no one has at the moment.

The path by which blood stem cells develop into megakaryocytes—the bone marrow cells that produce and release platelets into the bloodstream—is already known, Italiano says. We also know that platelets are essentially fragments of megakaryocytes that break off in response to some signal.

But that’s where our knowledge of platelet production largely ends. “Megakaryocytes themselves are something of a black box,” Italiano explains. “If you microinject the cytoplasm of an active megakaryocyte into a resting megakaryocyte, it will start to produce platelets as well. But we don’t know what factor or factors cause them to start platelet production.”

As Italiano and his laboratory peer into that black box, they know the stakes are big. Because in the end, they want to greatly reduce doctors’ and patients’ dependence on donated platelets.

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Cancer, inflammation, platelets and aspirin: Learning new tricks from an old drug

There are a couple of ways by which aspirin might affect cancer. (cpradi/Flickr)

Aspirin does a remarkable number of things in the body, enough that it’s said it would never win approval today from the Food and Drug Administration as an over-the-counter drug.

But among those functions are some that may explain something that doctors have recognized for some time: patients with cancer who have been taking aspirin tend to have better outcomes.

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Putting the squeeze on blood clots to stop a stroke

Blood should flow through an artery like water through a hose. The stress of a blockage can encourage clots to form, potentially resulting in a heart attack or stroke. Donald Ingber thinks the same forces could be used to help dissolve clots. (Beth Kingery/Flickr)

Grab a garden hose. Put your thumb over the end, but not all the way, and turn the water on. What happens? The water coming out of the hose gets squeezed as it tries to push past your thumb, putting a lot of force on the molecules in the water and making a big spray.

Now do the same thing with an artery: Partially block it with a clot and let blood flow through it. In this case, the force you’ve created in the artery could be lethal—creating fertile ground for blood clots that could lead to a stroke or heart attack.

But what if that combination of force and pressure could be used to stop something like a stroke instead? What if it could release a clot-dissolving drug on the spot? Donald Ingber, MD, PhD, a member of Boston Children’s Hospital’s Vascular Biology Program, had wondered that for many years. To find out, Ingber, who also directs the Wyss Institute for Biologically Inspired Engineering at Harvard, had his team start with a simple question: How do clots form?

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Mimicking milieus to produce platelets…for science and transfusion

Researchers and doctors dream of being able to artificially produce platelets (in the blood bag above) at clinically useful scales. A device that mimics the environments in which platelets mature could help them get there. (Toytoy/Wikimedia Commons)

The platelet – a crucial cog in our blood’s clotting machinery – is in high demand. Trauma, chemotherapy, and surgery patients often need platelet transfusions to keep their blood working properly. So too do people with genetic disorders like Wiskott-Aldrich syndrome that prevent them from producing enough platelets on their own and cause thrombocytopenia.

However, platelets are in short supply compared to other blood products, in part due to their short shelf life.

“Platelets only last in the body for about 10 days at a time,” explains Jonathan Thon, a fellow in the laboratory of Joe Italiano, a member of Children’s Vascular Biology Program. “In a blood bank, red blood cells can be stored in a refrigerator for 42 days, and plasma can be frozen for years. But platelets need to be stored at room temperature, and only for a short time for fear of bacterial contamination.” Which means that few platelets are available for those who need them – a situation that screams for a means of artificial platelet production.

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