NYSCF scientists develop new protocol to ready induced pluripotent stem cell clinical application

(Press-News.org) NEW YORK, NY (April 3, 2013) – A team of New York Stem Cell Foundation (NYSCF) Research Institute scientists led by David Kahler, PhD, NYSCF Director of Laboratory Automation, have developed a new way to generate induced pluripotent stem (iPS) cell lines from human fibroblasts, acquired from both healthy and diseased donors. Reported in PLOS ONE, this cell-sorting method consistently selects the highest quality, standardized iPS cells, representing a major step forward for drug discovery and the development of cell therapies.

Employing a breakthrough method developed by 2012 Nobel laureate Shinya Yamanaka, MD, PhD, adult cells are "reprogrammed" or reverted to an embryonic-like state, commonly through viral infection. Reprogramming is a dynamic process, resulting in a mixture of fully reprogrammed iPS cells, partially reprogrammed cells, and residual adult cells. Previous protocols to select promising fully reprogrammed cells rely primarily on judging stem cell colonies by eye through a microscope.

Cell colonies selected by qualitative measures could include partially reprogrammed cells, a major concern for clinical applications of cell therapies because these cells could become any other cell type in a patient following transplantation. Additionally for drug efficacy assays and toxicity investigations on iPS cells, heterogeneous cell populations can mar the response of representative iPS cell lines.

The NYSCF scientists developed a quantitative protocol, optimized over three and a half years, in order to consistently harvest early-reprogrammed cells. Using fluorescence activated cell sorting (FACS), fully reprogrammed cells were identified by two specific proteins, or pluripotency markers. The group then looked at third marker that is expressed by partially reprogrammed or adult cells, and they then negatively selected against these cells to obtain only fully reprogrammed cells.

"To date, this protocol has enabled our group to derive (and characterize over) 228 individual iPS cell lines, representing one of the largest collections derived in a single lab," said Dr. Kahler. "This standardized method means that these iPS cells can be compared to one another, an essential step for the use in drug screens and the development of cell therapies."

This process of selecting stem cell colonies provides the basis for a new technology developed by NYSCF, The NYSCF Global Stem Cell Array (Array), a fully automated, robotic platform to generate cell lines in parallel. Currently underway at the NYSCF Laboratory, the Array reprograms thousands of healthy donors' and diseased patients' skin and/or blood samples into iPS cell lines. Sorting and characterizing cells at an early stage of reprogramming allows efficient development of iPS cell clones and derivation of adult cell types.

"We are enthusiastic about the promise this protocol holds to the field. As stem cells move towards the clinic, Dr. Kahler's work is a critical step to ensure safe, effective treatments for everyone," said Susan L. Solomon, CEO of NYSCF.

### About The New York Stem Cell Foundation The New York Stem Cell Foundation (NYSCF) is an independent research institute founded in 2005 to accelerate cures and better treatments for patients through stem cell research. NYSCF has over 40 researchers in its New York laboratory and is an acknowledged world leader in stem cell research and in developing pioneering stem cell technologies, including the NYSCF Global Stem Cell Array. Additionally, NYSCF supports another 60 researchers at other leading institutions worldwide through its Innovator Programs, including the NYSCF – Druckenmiller Fellowships and the NYSCF-Robertson Investigator Awards. NYSCF focuses on translational research in a model designed to overcome the barriers that slow discovery and replaces silos with collaboration.

NYSCF researchers have achieved four major discoveries in the field, including: the discovery of a clinical cure to prevent transmission of maternal mitochondrial diseases in December 2012; the derivation of the first-ever patient specific embryonic stem cell line (#1 Medical Breakthrough of 2011 by Time magazine); the discovery of a new way to reprogram stem cells; and the creation of the first disease model from induced pluripotent stem cells (also named the #1 Medical Breakthrough by Time magazine in 2008). More information is available at http://www.nyscf.org.