The Scientistっていう雑誌に掲載された内容と私達（YS, AU) が描いたイラスト

インタビュー記事をコピペさせてもらいました。インタビュー内容が反映れていて満足です。下に元のアドレスを貼り付けます。なお、絵はいつものようにYS氏に描いてもらいました。COURTESY OF AKIHIRO UMEZAWA

http://www.the-scientist.com/?articles.view/articleNo/34783/title/Pluripotent-Until-Needed/

Regular Check-ups

GLYCAN PROFILING: Because iPSCs can revert to various differentiation states, they need to be periodically evaluated. Different iPSCs are covered in particular glycan patterns, depending on their differentiation. Therefore, Akihiro Umezawa and colleagues are using microarrays to scan for changes in these characteristic surface molecules.
View full sizeADAPTED BY ERIN LEMIEUX; COURTESY OF AKIHIRO UMEZAWAOnce an iPSC line has been established and validated, its differentiation potential might need to be monitored over the course of experimentation and passage. Stem cells have variable differentiation states, including pluripotency, multipotency, and unipotency. Since small fractions of iPSCs can spontaneously differentiate, it may be necessary to monitor the differentiation potential of an iPSC line as the cells are cultured and passaged.

Solution: A group of researchers in Japan, led by Akihiro Umezawa of the National Institute for Child Health and Development in Tokyo, has used lectin microarrays, produced by GP Biosciences of Sapporo, Japan, to monitor the differentiation status of iPSCs in the lab using patterns of glycans. Lectins are sugar-binding proteins from plants and animals, which can bind specifically to the glycans that cover a cell’s surface. Scientists have long used lectins to evaluate glycans, and Umezawa’s new method relies on 45 lectins that are spotted onto a glass slide to create a glycome-sensing microarray (LecChip by GP Biosciences).

Umezawa started by determining the glycome pattern on the surface of each iPSC differentiation type, in order to use these chips to quickly screen his cells. The protocol for the array analysis is easy, Umezawa says. Researchers extract the cell membrane proteins from as few as 100 cells using a commercially available kit (CelLytic MEM Protein Extraction kit from Sigma-Aldrich), label them with a fluorescent tag, hybridize the proteins to the array, and scan it using a GlycoStation Reader (GP Biosciences).

“We found discrete categories [of lectin array profiles] for each stem cell type using this technology, which was against my expectation,” Umezawa says.

Cost: Approximately $500 a chip.

Pros: The lectin microarray is fast and simple, requiring only a few hours to complete and a few days of training to master.

Cons: In order to compare and contrast profiles between cell lines and differentiated states in your lab, you need to first establish a database of glycan profiles for each cell line, which can be time-consuming and expensive.