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Stem cell research

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      June 23, 2009 -- Scientists have developed a way to harvest stem cells efficiently from placentas after birth, opening up a potential new source of the cells which can be used to treat a wide range of illnesses including sickle cell disease, thalassaemia and leukaemia.

      Frans Kuypers of the Children's Hospital and Research Centre in Oakland, California, led a team to extract the stem cells and found that placentas contained up to five times as many as cord blood, which has been used in recent years as a source of similar cells. His techniques are described in the latest edition of the journal Experimental Biology and Medicine. "Yes, the stem cells are there; yes, they are viable; and yes, we can get them out," said Kuypers. His team harvested the cells from the placentas of healthy women undergoing elective Caesarean sections. He believes the technique could probably be further optimised in future to harvest even more of the stem cells.

      Stem cells are the body's master cells and can be turned into almost any type of tissue – from brain cells to blood cells. The most versatile come from embryos but, because harvesting these results in the destruction of the embryo, many scientists are investigating other sources. Adults have stem cells too, for example in bone marrow, but these are less versatile than their embryonic cousins. A lot of recent attention has therefore focused on the potential of cord blood and placentas, which can be collected without any risk to babies, as a source of stem cells. Increasingly parents have been freezing the cord blood of their newborn children in the hope that it might one day prove useful for treatments.

      In his analysis, Kuypers showed that placenta stem cells have many of the characteristics of cord blood stem cells and might be even more "primitive", meaning they are more versatile. Scientists at the Children's Hospital in Oakland have already treated more than 100 children suffering from blood-related diseases using stem cells taken from the cord blood of siblings. But when a patient receives a cord blood transplant, said Kuypers, there are often not enough stem cells to treat their condition. Placentas may be a more rich source of the cells. "The more stem cells, the bigger the chance of success."

      His team's new technique uses drugs normally used to extract stem cells from bone marrow. The placenta is frozen after birth and treated with the drugs later, to avoid any harm to the baby or new mother. The technique would allow companies to gather and process placentas at a central location. "We're looking for a partnership with industry to get placenta-derived stem cells in large quantities to the clinic," said Kuypers. "Someday we will be able to save a lot more kids and adults from these horrific blood disorders."


      • #33

        October 28, 2009 -- Scientists have turned human stem cells into early-stage sperm and eggs in research that promises to give doctors an unprecedented insight into the causes of infertility. The work will allow researchers to study human reproductive cells from the moment they are created in embryos through to fully-mature sperm and eggs. Understanding the details of how sperm and egg cells grow will help scientists develop treatments for people who are left infertile when the process goes wrong. The research may also lead to treatments that can correct growth defects before a child is born. Genetic glitches that happen early on in the growth of sperm and eggs are a major cause of infertility in men and women. The process has been practically impossible to study until now though, because the sex cells form early on, before an embryo is two weeks old. "This achievement opens a new window into what was only recently a hidden stage of human development," said Susan Shurin at the National Institute of Child Health and Human Development, which part funded the research.

        A team led by Renee Reijo Pera at Stanford University in California developed a technique that turned human embryonic stem cells green when they started growing into sperm and eggs. After isolating the reproductive cells, the scientists worked out which genes made them grow properly by switching different genes on and off. Writing in the journal Nature, the scientists describe how that one gene, called DAZL, is involved in the formation of sex cells from the start. Two related genes are switched on later to steer the cells to full maturity. The main significance of the work is not to attempt to generate gametes for couples who do not produce them naturally. Rather, the work describes a system in which various aspects of germ cell development can be studied in a dish. In the current study, they have gained insight into the function of three genes in which they specialise."

        Darren Griffin, a geneticist at the University of Kent, said the work was important because it gave researchers a way to study human sperm and egg development in a dish, instead of having to rely on tissues taken from animals or "removing bits of people's gonads". "In future, a range of genetic and environmental factors could be studied, including the effects of pollutants on our fertility. Only through understanding such factors at a basic scientific level can we hope to develop novel diagnoses and therapies. The potential is enormous," he said. Allan Pacey, an andrologist at Sheffield University, said: "Ultimately this may help us find a cure for male infertility. Not necessarily by making sperm in the laboratory – I personally think that it unlikely – but by identifying new targets for drugs or genes that may stimulate sperm production to occur naturally. This is a long way off, but it is a laudable dream.


        • #34


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