2018/02/01
Kumamoto University
Keio University School of Medicine
Dr. Ryosei Minoda, Center Director of the Middle and Inner Ear Surgery Center, Department of Otolaryngology-Head and Neck Surgery at Kumamoto General Hospital, Japan Community Health Care Organization, and Dr. Daiki Takeda and his colleagues from the Department of Otolaryngology-Head and Neck Surgery at Kumamoto University, have succeeded for the first time in the world in a joint project with Professor Hideyuki Okano and his team from the Department of Physiology, Keio University School of Medicine. They successfully transplanted human iPS cell-derived inner ear cells into the inner ears of fetal mice, confirmed the engraftment of these cells in vivo, and demonstrated the expression of normal human-derived proteins in the inner ears of model mice via the transplanted cells.
There is still no fundamental treatment for hereditary hearing loss, which accounts for about half of all cases of congenital hearing loss. In many cases of hereditary hearing loss, the condition is already present at birth, and it is anticipated that treatment from an early fetal stage would be most effective for achieving more reliable therapeutic outcomes. Therefore, this research group has been focusing its research on treating hearing loss through in-utero therapy using fetal mice.
In this study, the research group generated inner ear progenitor cells (tissue stem cells that are the "source" of inner ear cells) from human-derived iPS cells and transplanted them into the inner ears of fetal normal mice and hearing loss model mice. The hearing loss model used was a model mouse that lacks connexin 30, one of the causative genes for hereditary hearing loss, and exhibits severe hearing loss similar to humans. The results showed that the transplanted cells engrafted within the inner ears of the mice, and it was demonstrated that some of the engrafted cells expressed connexin 30. In other words, this finding suggests the possibility of compensating for the missing connexin 30 through cell transplantation and improving hearing ability.
Using mice, the team succeeded for the first time in the world in cell transplantation into the fetal inner ear, a procedure previously considered technically difficult. They also confirmed the expression of a protein found in normal inner ear cells. This achievement is expected to lead to a new treatment method for hereditary hearing loss—inner ear regeneration through fetal therapy. It is also believed that it will greatly contribute to the advancement of various studies targeting the fetal inner ear.
This research was published in "Scientific Reports" on January 31, 2018 (UK time).
For the full press release, please see below.