Go and clot. A megakaryocytes branches to form two plates.
Dennis Kunkel Microscopy Inc./Visuals Unlimited / Corbis
Platelets are the sandbags of the circulatory system, accumulate in the wounds to create clots and minimize bleeding. Now, researchers in Japan have shown that they can produce large quantities of human platelets starting with the stem cells. Scaled up, the technique could provide a reliable source of replacement pads for patients
Platelets are the cells. they are fragments of bone marrow cells called megakaryocytes. patients and those suffering from diseases such as aplastic anemia cancer often do not produce enough of the blood-clotters, so they may require additional infusions, sometimes more than once a week. Platelets gleaned from blood donations are the source of these transfusions, but they have several drawbacks that have stimulated researchers to seek alternative. Because the fragments of cells can not be refrigerated, low temperatures damage-their life is only a few days, weeks against the red blood cells and platelets are more likely to be contaminated with dangerous bacteria. Denisa Wagner vascular biologist at Harvard Medical School in Boston highlights another motivation to identify new sources of platelets: the aging of the world population. Older people are more likely to need transfusions because they naturally produce fewer platelets, she notes.
In recent years, two teams reported having high human megakaryocytes and platelets from embryonic stem cells, called induced pluripotent stem cells (iPS) cells, adult cells returned to stem cells. However, neither technical provide enough platelets for transfusion. To increase efficiency, Koji Eto of Kyoto University in Japan, who led one of the teams, and colleagues have refined their recipe. By prodding human iPS cells and embryonic stem cells with drugs, they cranked the activity of three genes that prompt cells to divide and prevent them from committing suicide. This step resulted in megakaryocyte precursors, cells that can give rise to megakaryocytes. The team found that megakaryocytes precursors could survive and continue to divide in culture for more than five months, even after being frozen and thawed.
When the researchers switched off the three genes in removing drugs, cells matured into megakaryocytes and platelets started pumping. online today Cell Stem Cell , Eto and colleagues estimated that within 5 days of the method could produce enough platelets for transfusion. To test the platelets clotting capacity, researchers injected into mice who had blood vessel injury. The clots formed lab made pads in animals, the researchers showed.
To use this strategy medically Eto provides that megakaryocytes precursors were stored frozen. If necessary, they can be thawed and coaxed to specialize in wafer makers. Although megakaryocytes induced by the team are not as productive as those in the bone marrow, the growth of cells on a large scale could compensate for this inefficiency and allow the generation of large quantities of chips, he added. Eto said he plans to start clinical trials to laboratory wafers produced in 2 or 3 years.
Other researchers agree that this study brings closer field goal to derive usable platelets from stem cells. "I'm very impressed," said Nicolas Pineault stem cell biologist Canadian Blood Services in Ottawa. "I think it's very close" to be convenient for humans, said Wagner.
The quality of laboratory pads fact could be a stumbling block, however. for example, they are not as sticky as platelets born in the bone marrow, which may limit their clotting ability. "this is good chips, but they platelets are not excellent, "said Pineault. Researchers still have much work to do before that laboratory cultured platelets can replace those derived from donor says hematologist Poncz Mortimer of the University of Pennsylvania Perelman School of Medicine. "Are we still here? No. "
molecular geneticist Benjamin Kile of the Walter and Eliza Hall Institute of Medical Research in Australia recognized that many questions remain on laboratory plates made, including their ability to coagulation and lifespan in humans. But he said Eto and colleagues have the merit of showing that it is possible to produce large quantities of cell fragments. "you can not do clinical trials until you have managed to grow enough pads, "he said.
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