New Reprogramming Method Makes Better Stem Cells
A team of researchers from the University of California, San Diego School of Medicine, Oregon Health & Science University (OHSU) and Salk Institute for Biological Studies has shown for the first time that stem cells created using different methods produce differing cells. The findings, published in the July 2, 2014 online issue of Nature, provide new insights into the basic biology of stem cells and could ultimately lead to improved stem cell therapies.
Capable of developing into any cell type, pluripotent stem cells offer great promise as the basis for emerging cell transplantation therapies that address a wide array of diseases and conditions, from diabetes and Alzheimer’s disease to cancer and spinal cord injuries. In theory, stem cells could be created and programmed to replace ailing or absent cells for every organ in the human body.
The gold standard is human embryonic stem cells (ES cells) cultured from discarded embryos generated by in vitro fertilization, but their use has long been limited by ethical and logistical considerations. Scientists have instead turned to two other methods to create stem cells: Somatic cell nuclear transfer (SCNT), in which genetic material from an adult cell is transferred into an empty egg cell, and induced pluripotent stem cells (iPS cells), in which adult cells are reverted back to a stem cell state by artificially turning on targeted genes.
Until now, no one had directly and closely compared the stem cells acquired using these two methods. The scientists found they produced measurably different results. “The nuclear transfer ES cells are much more similar to real ES cells than the iPS cells,” said co-senior author Louise Laurent, PhD, assistant professor in the Department of Reproductive Medicine at UC San Diego. “They are more completely reprogrammed and have fewer alterations in gene expression and DNA methylation levels that are attributable to the reprogramming process itself.”
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Pictured: Scanning electron micrograph of cultured human neuron from induced pluripotent stem cell. Image courtesy of Mark Ellisman and Thomas Deerinck, National Center for Microscopy and Imaging Research, UC San Diego