Hair Cell Regeneration Study Announced

Editor: Here's some more exciting news on the topic of hair cell regeneration. You may recall that scientists have identified a "switch" that turns the production of hair cells in mammals on and off. The next challenge is controlling that switch, so that the production process can be properly managed. Sirna Therapeutics and Massachusetts General Hospital have announced a collaboration to pursue that goal.

I've included portions of the press release below. If you'd like to read the entire press release (including appropriate disclaimers if you're thinking of investing in Sirna ;-), please point your browser to http://tinyurl.com/bwtpj

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BOULDER, Colo., and SAN FRANCISCO, June 13 /PRNewswire-FirstCall/ -- Sirna Therapeutics, Inc. (NASDAQ:RNAI), a leading RNAi therapeutics company, announced today that it has entered into a sponsored research collaboration with Dr. Zheng-Yi Chen at Massachusetts General Hospital, a teaching hospital of Harvard Medical School. Under the collaboration, Sirna will provide Dr. Chen and his team short interfering RNAs (siRNAs) and related formulations to evaluate their effectiveness as modulators of the retinoblastoma (pRb) gene pathway to promote re-growth and differentiation of hair cells that under natural conditions do not grow or divide in adult mammals.

Previous research by Dr. Chen's lab demonstrated that selectively knocking out the retinoblastoma protein (pRb) in the mouse inner ear can foster regeneration and differentiation of hair cells whose function is to convert sound vibrations into nerve impulses. These results were published in a recent issue of the journal Science in a study that concluded that modulation of the pRb pathway may ultimately lead to mammalian hair cell regeneration, differentiation and functional recovery. Sirna and Dr. Chen believe that a chemically modified siRNA, by virtue of its potency and specificity, is a viable modality for the transient modulation of the pRb pathway.

Dr. Zheng-Yi Chen, Assistant Professor, Neurology Service, Center for Nervous System Repair at Massachusetts General Hospital and Harvard Medical School, said, "The research to be supported by Sirna will fundamentally test the hypothesis that a modified siRNA can be effective in selectively turning off, or 'knocking down,' the retinoblastoma protein which plays a key role in controlling growth and division of inner ear hair cells in mammals. We also intend to ascertain whether any ensuing protein knockdown from RNAi has the desired therapeutic impact of restoring hearing."

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About Hair Cells

Named for the hair-like projections on their surfaces, hair cells form a ribbon of vibration sensors along the length of the cochlea, the organ of the inner ear that senses sound. Receiving sonic vibrations though the eardrum and bones of the middle ear, hair cells convert them to electrical signals that are carried to the brain by the auditory nerve. Among the earliest structures to form in embryonic development, hair cells are very sensitive to damage from a variety of sources including excessive noise, toxins, and/or infection. If damaged, hair cells will not naturally regenerate in mammals, and their death in sufficient numbers accounts for most types of hearing loss.

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