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2012 Articles

Due to copyright restrictions, the full text of articles linked below is available only to the NIH community. Those outside the NIH community can access citations and abstracts.

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  • Scientists Generate Embryo Using Material from 3 Different Individuals: Individuals inherit mitochondrial disorders via defective mitochondrial DNA found in the cytoplasm of their mother’s egg. Mitochondria normally serve as a cell’s powerhouse. In the case of inherited mitochondrial disorders, however, the defective mitochondria fail to produce needed energy. This causes cell injury, or even cell death and organ damage, especially in tissues such as the brain, heart, liver, skeletal muscles and kidneys, which require a ot of energy. Currently, there is no way to correct this type of disorder once an individual inherits it. Now, scientists have developed a possible method for preventing inheritance of mitochondrial disorders—donated egg cytoplasm. They transplanted nuclear DNA from an egg whose mitochondrial DNA carries a disorder into a second, normal human egg whose nuclear DNA was removed. After fertilization, the resulting embryo carries material from 3 different individuals: nuclear DNA from one woman, normal mitochondrial DNA from another woman, and DNA from the man’s sperm. Although approximately half of the oocytes with transplanted nuclear DNA did not fertilize normally, other embryos developed to the blastocyst stage and produced embryonic stem cells similar to controls. Scientists hope to optimize this procedure, so that it may one day be used to help women whose eggs have abnormal mitochondrial DNA to give birth to children who do not inherit these mitochondrial disorders. Nature [Epub ahead of print]; Laboratory of S. Mitalipov (Non-NIH-supported). 2012 Oct 24.

  • Eggs Generated from Mouse Stem Cells Produce Live Mice: Scientists have coaxed stem cells into making many different types of cells found in the body, but successful generation of mature eggs remained elusive. Now, scientists from Japan report that they’ve used both mouse embryonic stem cells (ESCs) and mouse cells reprogrammed to behave like stem cells, called induced pluripotent stem cells (iPSCs), to generate mouse egg precursor cells. Next, they combined the egg precursors with fetal mouse ovary cells and implanted them in a mouse ovary. The mouse ovary helped the egg precursors develop into mature eggs, or oocytes, which the scientists then retrieved and fertilized in vitro to create an embryo. The scientists implanted the resulting embryos into mouse foster mothers, and the embryos survived and matured into live mice pups about four percent of the time. This report illuminates critical steps needed to generate a mature oocyte from stem cells. However, the complicated protocol used to conduct these experiments in mice would not be practical for use in human beings. Science [ePub Ahead of Print]; Laboratory of M. Saitou (Non-NIH supported). 2012 October 4.

  • Brains of Deaf Adult Gerbils Respond to Sound after Implant of Human Embryonic Stem Cell-Derived Early Ear Cells: An individual who loses his or her hearing due to loss of hair cells in the inner ear may be able to regain some hearing by using a hearing aid or cochlear implant. However, sometimes hearing loss is caused by the death of nerve cells called auditory neurons, which carry sound from the hair cells in the cochlea to the brain. There is currently no standard treatment to restore hearing lost due to auditory neuron death. Hoping to use stem cells to address this problem, scientists raised human embryonic stem cells (hESCs) in a tissue culture environment meant to recapitulate normal development of the mammalian ear. hESCs grown under this protocol took on characteristics of early ear cells, which can become either hair cells or auditory neurons. When the scientists transplanted the auditory neuron-like cells into deaf adult gerbils, the cells made connections with hair cells in the ear and with the brain. Tests showed that the brains of animals that had received a transplant were able to respond to sound, in spite of having been deaf prior to treatment. Scientists now hope to refine this technique to treat deafness in humans. Nature [epub ahead of print]; laboratory of M.N. Rivolta (Non-NIH-supported). 2012 September 12.

  • Arsenic turns stem cells cancerous:  Researchers at the National Institutes of Health have discovered how exposure to arsenic can turn normal stem cells into cancer stem cells and spur tumor growth.  Read the press release. Environ Health Perspect [epub ahead of print]; laboratory of MP Waalkes (NIH-supported). 2012 March 27.

  • Women May Be Able to Make New Eggs: In 2004, NIH-supported scientists challenged the standard textbook representation of mammalian reproduction—that female mammals are born with the total number of eggs that they will ever make. (See: A Challenge to Developmental Dogma: Adult Mammals May Yet Produce Eggs). Their research demonstrated that adult female mice can make new eggs. Now, they present evidence that women of reproductive age are also capable of making new eggs. They used their knowledge of these rare cells from adult female mice to identify similar cells in adult human ovaries that still divide, can be grown in culture, and appear to mature into eggs. If other labs are able to replicate these results, the reported technique will help scientists better understand human egg development and may one day lead to treatments for infertility. Nat Med 18: 413–21; laboratory of J. Tilly (NIH-supported). 2012 February 26.

  • Preliminary Report: Stem Cell-Derived Treatments for Eye Disease: Age-related macular degeneration (AMD) is a leading cause of vision loss in Americans 60 years of age and older. AMD is caused by loss or damage to light-sensitive cells (photoreceptors) at the back of the eye, and loss or damage to the supporting cells (called retinal pigmented epithelium, or RPE) that nourish the photoreceptors. Stargardt disease is an inherited form of macular degeneration that shows up earlier in life, rather than during aging. Scientists hope to treat these eye diseases by replacing the RPE cells, and have developed a protocol to coax human embryonic stem cells (hESCs) to differentiate into RPE cells. The eye is a good place to test stem cell-derived treatments, because it is somewhat self-contained and it is immune-privileged (i.e. the immune system is less active there). This means that cells transplanted into the eye are less likely to be attacked and destroyed by the recipient's immune system. Now scientists are testing whether hESC-derived RPE cells can be transplanted into the human eye to replace RPE cells damaged or destroyed by disease. In a Phase I clinical trial, designed to test the safety and tolerability of a proposed therapy, scientists injected hESC-derived RPEs into one eye of one patient with AMD. In a second Phase I trial, they injected hESC-derived RPEs into one eye of a patient with Stargardt disease. (See the description of the Phase I AMD trial and the Phase I Stargardt disease trial on the website.) Both patients tolerated the treatment well, and both reported improved vision in the treated eye. These very early results from the Phase I trials provide hope that patients may one day benefit from hESC-derived RPE treatment. However, the current report is preliminary and describes only two patients. In order to gain broad acceptance, the treatment must involve more patients, and it must still be tested in Phase II and Phase III Clinical Trials. Lancet [epub ahead of print]; laboratory of S. Schwartz (non-NIH supported). 2012 January 24.

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