Placenta: New Source for Harvesting Stem Cells

Children's Hospital Oakland scientists first to discover new source for harvesting stem cells Tuesday, 23 June 2009 A groundbreaking study conducted by Children's Hospital & Research Center at Oakland, California, is the first to reveal a new avenue for harvesting stem cells from a woman's placenta, or more specifically the discarded placentas of healthy newborns. The study also finds there are far more stem cells in placentas than in umbilical cord blood, and they can be safely extracted for transplantation. Furthermore, it is highly likely that placental stem cells, like umbilical cord blood and bone marrow stem cells, can be used to cure chronic blood-related disorders such as sickle cell disease, thalassaemia, and leukaemia. The study, led by Children's Hospital & Research Center Oakland scientists Frans Kuypers, PhD, and Vladimir Serikov, PhD, will be the feature story in the July 2009 issue of Experimental Biology and Medicine. The doctors and their team made the discoveries by harvesting term placentas from healthy women undergoing elective Caesarean sections. "Yes, the stem cells are there; yes, they are viable; and yes, we can get them out," declared Dr. Kuypers. Stem cells are essentially blank cells that can be transformed into any type of cell such as a muscle cell, a brain cell, or a red blood cell. Using stem cells from umbilical cord blood, Children's Hospital Oakland physicians have cured more than 100 kids with chronic blood-related diseases through their sibling donor cord blood transplantation program, which began in 1997. However, according to the American Cancer Society, each year at least 16,000 people with serious blood- related disorders are not able to receive the bone marrow or cord blood transplant they need because they cannot find a match. Dr. Kuypers explained that even when a patient receives a cord blood transplant, there may not be enough stem cells in the umbilical cord to successfully treat their disorder. Placentas, however, contain several times more stem cells than umbilical cord blood. "The greater supply of stem cells in placentas will likely increase the chance that an HLA (human leukocyte antigen) matched unit of stem cells engrafts, making stem cell transplants available to more people. The more stem cells, the bigger the chance of success," said Dr. Kuypers.

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This is a microphotograph of chorionic villus of human term placenta immunostained for CD34 (Marker of endothelial and haematopoietic stem cells, red), CD31 (marker of endothelial cell, green) and nuclei (DAPI, blue). Non-endothelial CD34-positive cell is clearly observed in tissue of placenta. Credit: Society for Experimental Biology and Medicine.

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In this report, said Dr. Serikov, we demonstrate for the first time that human placentas could provide abundant amounts of CD34+ CD133+ colony-forming cells, as well as other primitive hematopoietic progenitors, suitable for transplantation in humans. The total amount of live haematopoietic stem cells, or colony-forming units in culture that could be obtained from placentas was an order of magnitude larger than the number of hematopoietic stem cells obtained from cord blood from the same source. Haematopoietic stem cells which maintain their differentiation capacity, as well as stromal stem cells that support long-term culture of haematopoietic cells, can be harvested from perfusate of placenta following CXCR4 receptor blockade, said Dr. F. Kuypers. Importantly, live HPCs can similarly be obtained from whole cryopreserved placentas. Cells derived from placental tissue differentiated into all blood lineages in vitro. Animal experiments further demonstrated successful engraftment of placenta-derived HSC, which reconstituted haematopoiesis in immunodeficient mice. In summary, said Dr. F. Kuypers, our results indicate for the first time that human term placenta is a high capacity source of live and functional hematopoietic stem cells. By using placental circulation and stem cell receptor blockade an abundant amounts of hematopoietic stem cell could be easily obtained in sterile conditions by non-destructive methods. Dr. Steven R. Goodman, Editor-in-Chief of Experimental Biology and Medicine said "the outstanding importance of these results for practical haematology is determined by the fact that total number of stem cells that can be harvested from cord blood limits the efficacy of this stem cell source for transplants only to small children. These novel findings demonstrate that placenta may provide a source of autologous stem cells sufficient for reconstitution of haematopoiesis in adult patients. Use of methods to obtain haematopoietic cells from placenta, developed by Dr. Serikov and Dr. Kuypers as augmentation of cord blood-based therapy or replacement of bone marrow for transplantation will dramatically change whole field of transplantology." Drs. Kuypers and Serikov have also developed a patent-pending method that will allow placental stem cells to be safely harvested and made accessible for transplantation. The process involves freezing placentas in a way that allows them to later be defrosted and suffused with a compound that enables the extraction of viable stem cells. The method will make it possible for companies to gather, ship and store placentas in a central location. "We're looking for a partnership with industry to get placenta-derived stem cells in large quantities to the clinic," said Dr. Kuypers. He adds that much more research and grant funding are needed to explore the maximum potential of this latest discovery. He remains encouraged. "Someday, we will be able to save a lot more kids and adults from these horrific blood disorders." ......... ZenMaster

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For more on stem cells and cloning, go to CellNEWS at http://cellnews-blog.blogspot.com/ and http://www.geocities.com/giantfideli/index.html

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