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Archive - Jul 26, 2013

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Human Stem-Cell-Derived Liver Cells Regenerate Liver Function in Mice

Researchers have generated functional hepatocytes from human stem cells, transplanted them into mice with acute liver injury, and shown the ability of these stem-cell-derived human liver cells to function normally and increase survival of the treated animals. This promising advance in the development of cell-based therapies to treat liver failure resulting from injury or disease relied on the development of scalable, reproducible methods to produce stem-cell-derived hepatocytes in bioreactors, as described in an article pubished online on July 9, 2013 in Stem Cells and Development, a peer-reviewed journal from Mary Ann Liebert, Inc., publishers. First author Dr. Massoud Vosough and coauthors, including senior author Dr. Hossein Baharvand, demonstrate a large-scale, integrated manufacturing strategy for generating functional hepatocytes in a single suspension culture grown in a scalable stirred bioreactor. In the article, the authors describe the method used for scale-up, differentiation of the pluripotent stem cells into liver cells, and characterization and purification of the hepatocytes based on their physiological properties and the expression of liver cell biomarkers. Dr. David C. Hay, MRC Centre for Regenerative Medicine, University of Edinburgh, U.K., comments on the importance of Vosough et al.'s contribution to the scientific literature in his editorial in Stem Cells and Development entitled "Rapid and Scalable Human Stem Cell Differentiation: Now in 3D." The researchers "developed a system for mass manufacture of stem-cell-derived hepatocytes in numbers that would be useful for clinical application," creating possibilities for future "immune-matched cell-based therapies," says Dr. Hay. Such approaches could be used to correct mutated genes in stem cell populations prior to differentiation and transplantation, he adds.

Mechanism Underlying Amazing Ability to Change Color in Squid and Octopus

Color in living organisms can be formed in two ways: pigmentation or anatomical structure. Structural colors arise from the physical interaction of light with biological nanostructures. A wide range of organisms possess this ability, but the biological mechanisms underlying the process have been poorly understood. Two years ago, an interdisciplinary team from the University of California at Santa Barbara (UCSB) discovered the mechanism by which a neurotransmitter dramatically causes changes of color in the common market squid, Doryteuthis opalescens. That neurotransmitter, acetylcholine, sets in motion a cascade of events that culminate in the addition of phosphate groups to a family of unique proteins called reflectins. This process allows the proteins to condense, driving the animal's color-changing process. Now the researchers have delved more deeply to uncover the mechanism responsible for the dramatic changes in color used by such creatures as squids and octopuses. The findings were published in the February 12, 2013 issue of PNAS, in a paper by molecular biology graduate student and lead author Daniel DeMartini and co-authors Dr. Daniel V. Krogstad and Dr. Daniel E. Morse –– and are described in an article by Dan Crossins in the July 1, 2013 issue of The Scientist. Structural colors rely exclusively on the density and shape of the material rather than its chemical properties. The latest research from the UCSB team shows that specialized cells in the squid skin called iridocytes contain deep pleats or invaginations of the cell membrane extending deep into the body of the cell. This creates layers or lamellae that operate as a tunable Bragg reflector.