Moreover, the soluble cysteine-rich domain of Frizzled-8 (a Wnt inhibitor) blocked endogenous Wnts and the effects of Wnt-1 and -5a on proliferation and the acquisition of a DA phenotype in precursor cultures. In contrast, Wnt-5a primarily increased the proportion of Nurr1+ precursors that acquired a neuronal DA phenotype and up-regulated the expression of Ptx3 and c-ret mRNA. Wnt-1 predominantly increased the proliferation of Nurr1+ precursors, up-regulated cyclins D1 and D3, and down-regulated p27 and p57 mRNAs.
Instead, Wnt-1 and -5a increased the number of rat midbrain DA neurons in rat embryonic day 14.5 precursor cultures by two distinct mechanisms. Wnt-3a promoted the proliferation of precursor cells expressing the orphan nuclear receptor-related factor 1 (Nurr1) but did not increase the number of tyrosine hydroxylase-positive neurons. We also found that Wnt-1, -3a, and -5a expression is differentially regulated during development and that partially purified Wnts distinctively regulate VM development. Our results show that β-catenin is expressed in DA precursor cells and that β-catenin signaling takes place in these cells, as assessed in TOPGAL reporter mice. In our study, we examined the contribution of Wnts to the development of ventral midbrain (VM) dopaminergic (DA) neurons. Connective tissue StemCells Sunnyvale, Calif.The Wnts are a family of glycoproteins that regulate cell proliferation, fate decisions, and differentiation. Perhaps advances like PPL’s will, at the very least, make discussion of these issues possible.Ĭompanies Researching Adult Stem Cells COMPANY LOCATION STEM CELL TYPE Aastrom Biosciences Ann Arbor, Mich. So far, the ethical debate on deriving stem cells from embryos has obscured such vital scientific questions. The potential that they would explode into a cancerous mass after a stem cell transplant might turn out to be the Pandora’s box of stem cell research.” University of Pennsylvania bioethicist Glenn McGee is one of the most vocal critics on this point: “The emerging truth in the lab is that pluripotent stem cells are hard to rein in. Some researchers, however, are beginning to argue that these limitations would actually make tissue-specific stem cells safer than their pluripotent counterparts.
“The benefits are ethical on the one hand, and they could be practical on the other,” says Ron James, PPL’s chief executive.īecause they have traveled further on a pathway of differentiation than an embryo’s cells have, such tissue-specific stem cells are believed by many to have more limited potential than ES cells or those that PPL hopes to create.
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If PPL succeeds, it will free researchers and eventually doctors from their reliance on a relatively rare commodity: aborted fetuses and embryos left over from in vitro fertilization. In October, PPL’s labs in Blacksburg, Va., won a $1.9 million grant from the National Institute of Standards and Technology (NIST) for research on reprogramming adult cells to be pluripotent. The potential of ES cells to treat a spectrum of diseases lies in the fact that the cells are “pluripotent,” meaning they can form any tissue in the adult body. Scotland-based PPL Therapeutics hopes to end the debate once and for all by developing an unlimited source of stem cells-without ever creating or destroying an embryo.
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Critics, on the other hand, argue that the ethical cost of using ES cells, which are derived from human embryos, is too high. Nurenyxs Decentralized Clinical Studies Software revolutionizes the way clinical studies are conducted ensuring the integrity and security of clinical data. Proponents of ES cell research say that the promise of the cells in treating diseases ranging from heart failure to paralysis is invaluable. Ever since human embryonic stem (ES) cells were first isolated in 1998, a debate over their use has raged.
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