Stem cell transplantation into mouse cochlea may impact future hearing loss therapies

Public release date: 26-Jun-2012 [ | E-mail | Share ]

Contact: David Eve celltransplantation@gmail.com Cell Transplantation Center of Excellence for Aging and Brain Repair

Putnam Valley, NY. (June 26 , 2012) Researchers in Japan who evaluated the risks and efficacy of transplanting two varieties of stem cells into mouse cochlea have concluded that both adult-derived induced pluripotent stem (iPS) cells and mouse embryonic stem (ES) cells demonstrate similar survival and neural differentiation capabilities. However, there is a risk of tumor growth associated with transplanting iPS cells into mouse cochleae. Given the potential for tumorigenesis, they concluded that the source of iPS cells is a critical issue for iPS cell-based therapy.

Their study is published in a recent issue of Cell Transplantation (21:4), now freely available on-line at http://www.ingentaconnect.com/content/cog/ct/,

"Hearing loss affects millions of people worldwide," said Dr. Takayuki Nakagawa of the Department of Otolaryngology, Graduate School of Medicine, Kyoto University, Japan. "Recent studies have indicated the potential of stem-cell based approaches for the regeneration of hair cells and associated auditory primary neurons. These structures are essential for hearing and defects result in profound hearing loss and deafness."

The authors noted that embryonic stem cells have previously been identified as promising candidates for transplantation, however they have also been associated with immune rejection and ethics issues. Consequently, this study compared the survival and neural differentiation capabilities of ES and three clones of mouse iPS cells.

"Our study examined using induced pluripotent stem cells generated from the patient source to determine if they offer a promising alternative to ES cells," explained Dr. Nakagawa. "In addition, the potential for tumor risk from iPS cells needed clarification."

Four weeks after transplantation, the researchers found that the majority of cochleae that had been transplanted exhibited the settlement of iPS or ES-derived neurons. However, there was a difference in the number of cells present based on cell lines. They noted that the number of cells able to be transplanted into cochleae is limited because of the cochleae's tiny size. Thus, the number of settled cells is low.

They also noted the formation of a teratoma (encapsulated tumor) in some cochlea after transplantation with one group of iPS cells.

"To our knowledge, this is the first documentation of teratoma formation in cochleae after cell transplantation," said Dr. Nakagawa.

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Stem cell transplantation into mouse cochlea may impact future hearing loss therapies