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Human Term Placenta Is A New Abundant Source Of Hematopoietic Cells

June 24, 2009

Investigators at Children’s Hospital Oakland Research Institute, Oakland, California found a way to obtain large numbers of hematopoietic stem cell from human term placenta. The results, which appear in the July 2009 issue of Experimental Biology and Medicine, describe detailed report on quantification, characterization, engraftment capacity, and most importantly, practical way to obtain hematopoietic stem cells from placenta in numbers that are several-fold higher than could be obtained from cord blood.

The research team, Dr. Vladimir Serikov, MD, PhD, D.Sci, Assistant Staff Scientist, Catherin Hounshell, a research associate, Sandra Larkin, a research associate, Mr. William Green, student, Dr. Hurokazy Ikeda, MD, Visiting Scientist, Dr. Mark Walters, Medical Director of Children’s Hospital Oakland Hematology and Oncology Programs, and Dr. Frans Kuypers, Senior Scientist, performed studies in human term placentas, human cord blood, and immunodeficient mice. Dr. Serikov said, that the fact the human term placenta is a hematopoietic organ was reported by our team for the first time more then a year ago, and this year this finding was confirmed by UCSF scientists headed by Dr. S. Fisher.

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 hematopoitic 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. Hematopoietic stem cells which maintain their differentiation capacity, as well as stromal stem cells that support long-term culture of hematopoietic 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 hematopoiesis 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 hematology 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 hematopoiesis in adult patients. Use of methods to obtain hematopoietic cells from placenta, developed by Dr. Serikov and Dr. Kuypers as augumentation of cord blood-based therapy or replacement of bone marrow for transplantation will dramatically change whole field of transplantology.”

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Caption: This is a microphotograph of chorionic villus of human term placenta immunostained for CD34 (Marker of endothelial and hematopietic 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.
Image Credit: Society for Experimental Biology and Medicine

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