Scientists at the University of California, Los Angeles (UCLA) have developed what they claim is a fully chemically defined, animal-free alternative to standard mouse feeder cell- and and bovine sera-containing culture systems for human embryonic stem cells (hESCs). They claim their new culture system represents a genuinely scalable single-cell passaging system for the long-term propagation and maintenance of hESCs that will help address what could otherwise represent significant regulatory and cGMP-related stumbling blocks for the future transfer of stem cell-based regenerative therapies from the lab to the clinic and commercial arena.
Their results were achieved through a collaboration between UCLA stem cell scientists and researchers at the University’s School of Engineering and Applied Science. The work is published in Nature Communications, in a paper titled, “An optimized small molecule inhibitor cocktail supports long-term maintenance of human embryonic stem cells.”
The breakthrough in discovering the optimum set of ingredients for a culture medium capable of supporting the long-term, single-cell passaging of hESCs was achieved through a two-year collaboration between UCLA’s Hideaki Tsutsui, Ph.D., and Bahram Valamehr, previously a graduate student at UCLA’s Geffen School of Medicine. The researchers founded their work on data and analyses of stem cells generated at the laboratory of Hong Wu, Ph.D., David Geffen professor of molecular and medical pharmacology at UCLA’s Geffen School of Medicine, and a researcher at UCLA’s Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research. Importantly, Tsutsui and Valamehr used a feedback system control (FSC) scheme to screen huge numbers of possible combinations of ingredients for the hESC medium. This FSC approach was originally developed by UCLA professor Chih-Ming Ho, Ph.D., to search for the best drug combinations capable of inhibiting viral infection or killing cancer cells. Dr. Chih-Ming Ho is the Ben Rich-Lockheed Martin professor at the UCLA Henry Samueli School of Engineering and Applied Science.
Using the FSC technique, the researchers identified a particular combination of three small molecule inhibitors, supplemented by basic fibroblast growth factor (bFGF), which they state supports long-term maintenance of hESC cultures through routine single-cell passaging. “Although other studies have demonstrated growth of hESC under defined media formulations and/or on defined surfaces, to the best of our knowledge this is the first study that combines defined cultures with routine single-cell passaging, which plays an important role in supplying a large mass of clinically applicable cells,” claims Dr. Tsutsui, lead author of the paper in Nature Communications. "Thus, our hES cell culture system, guided by the FSC technique, will bring hES cells one step closer to clinical therapies.”
“What is significant about this work is that we’ve been able to very rapidly develop a chemically defined culture medium to replace serum and feeders for cultivating clinical-grade hES cells, thereby removing a major roadblock in the area of regenerative medicine,” adds Dr. Chih-Ming Ho, senior author of the paper and also director of the Center for Cell Control at UCLA Engineering. “This is the best example of demonstrating the strength and potential of interdisciplinary collaborations. Engineers and biologists working side by side can accomplish a mission impossible.”