京都大學用人類ｉＰＳ細胞膜改善老鼠心機功能

A few weeks ago the Mainichi News on-line reported the following:

ｉＰＳ:心機能改善　京大、ラットにヒト細胞シート

毎日新聞　2014年10月22日　22時15分（最終更新　10月22日　22時47分）

　京都大ｉＰＳ細胞研究所の山下潤教授は２２日、心筋や血管の細胞がシート状に並んだ「心臓組織シート」をヒトｉＰＳ細胞から作り、心筋梗塞（こうそく）状態にしたラットの心臓に移植して心機能を改善させることに成功したと発表した。研究が進めば、重い心臓病の有望な治療法となる可能性がある。オンライン科学誌サイエンティフィック・リポーツに同日、掲載された。

　重症の心筋症患者の心臓は筋肉細胞が失われ、心臓の機能が低下している。根本的な治療は心臓移植しかなく、ｉＰＳ細胞などから心筋を作って移植する再生医療への期待が高まっている。これまでバラバラの細胞を心臓に直接注入して移植する方法などが試みられたが、定着率が低いことが課題だった。

　研究グループはヒトｉＰＳ細胞を変化させ、心筋細胞（約７２％）と血管内皮細胞（約６％）、血管壁細胞（約２０％）からなる細胞シートの作製に成功した。グループによると、心筋細胞だけではなく、血管の細胞もｉＰＳ細胞から作製し、シート状に形成したのは初めてという。

　人工的に心筋梗塞の状態にしたラットの心臓にこのシートを３枚重ねて張り付けると、１カ月後に心機能は約１．６倍に改善。移植部分に血管が新たに作られ、移植した心筋細胞が多く残っていたという。

　人への応用には、豚やサルで有効性や安全性を確認する必要がある。大阪大のグループも既に、ｉＰＳ細胞を使って別の方法で心筋シートを作り、心臓病治療につなげる研究を進めている。山下教授は「（阪大などの方法の）次の世代の治療法として応用できるのではないか」と話している。【根本毅】

(試譯文)

On the 22nd (October) professor Yamashita Jun of the Kyoto University iPS Cells Research Center announced that he had succeeded, using cells from human iPS cells, in transplanting the cells of the heart muscle and blood vessels that were lined up in a sheet, the "cardiac tissue sheet", into the heart of a rat which had myocardial infarction (infarct), and making improve in its cardiac function. As this study was developed, there was a possibility that serious heart disease could have a hope for cure. On the same day, this announcement appeared in the on-line science magazine: the Scientific Reports.

   In a patient with serious myocardial infarction, the muscle cells in the heart were lost, and the function of the heart decreased. There was an increasing expectation on the regenerative medicine of transplanting myocardium made from iPS cells, without doing the fundamental treatment of a heart-transplant. Up to now a transplant by directly injecting loose cells into a heart was tried, but the problem was that its fixing rate was low.

   A study group, by causing changes in the human iPS cells, had succeeded in producing a cell-sheet which consisted of myocardial cells (about 72 %), vascular endothelial cells (about 6 %) and blood vessel parietal cells (about 20 %). According to the group, it was the first time not only myocardial cells, but also blood vessel cells were made from iPS cells and formed into a sheet.

   When three such sheets were overlapped and attached to the heart of a rat which was in a state of myocardial infarction that was induced artificially, the cardiac function improved by about 1.6 times one month later. In the transplanted part, new blood vessels were being made, and many transplanted cardiac muscle cells were still surviving.

   Its application on human would require safety and validity confirmation on pigs and apes. This group in Osaka University had already made myocardial sheets in a different way by using iPS cells, and the study linked to heart disease treatment was being advanced. Prof. Yamashita said that “(the way of the Osaka University) may be used as a treatment method in the next generation".

The research result on iPS cells achieved by Professor Yamashita Jun has provided new hope to patients with serious myocardial infarction.