Scientists have developed an alternative to animal-based materials such as Matrigel-coated plates for culturing the stem cells, which produce cells that are cells unsuitable for medical use. First, they identified a specific signaling pathway, called Rho-Rock, which the hESCs use during colony formation and which plays an important role in physical interactions between hESCs. When this pathway is blocked, researchers found that the normal colony formation of hESCs was considerably impaired, and that the hESCs maintained their pluripotency.

In the study, sato's group extensively screened various types of scaffold materials in combination with Y27632, a chemical compound that blocks the Rho-Rock pathway, and found that the Matrigel coating could be replaced with "poly-D-lysine," a chemically synthesized ECM. The major advantages of poly-D-lysine over Matrigel are that poly-D-lysine is completely animal-free, easy to handle, and its quality is consistent.

"We found that the growth of the hESCs under this novel culture condition was almost identical to the growth of hESCs on Matrigel-coated culture plates, with no compromise in pluripotency," Sato said.

The group is now working on producing animal-free "induced pluripotent stem (iPS) cells" - pluripotent stem cells artificially derived from adult cells without using embryos.

Photo: hESCs grown on poly-D-lysine-coated plate in defined culture media with Y27632. Photo credit: Sato lab, UC Riverside.