Reprogramming with small molecules and the polycistronic vector was further validated on multiple human fibroblast cell lines in both feeder- and serum-free conditions. Chemical treatment improved reprogramming in StemPro® medium on Geltrex™-coated plates (Life Technologies) and in mTeSR®1 medium (Stemcell Technologies) on BD Matrigel™-coated plates (BD Biosciences), although a decreased kinetics of reprogramming was observed when compared to culture on feeder cells (Figure 3).
The enhancement of reprogramming by chemical treatment has also been demonstrated using other human fibroblast cell lines.
Use of small molecules that modulate key signaling pathways and epigenetic modifiers enables dramatic improvement in the quality and quantity of human iPS colonies generated.
Human iPS Cell Boost Supplement enhanced colony formation by two- to threefold when used in combination with the mouse STEMCCA lentivirus kits and 15-fold when used in combination with the human STEMCCA lentivirus kits.
Human iPS colonies generated in the presence of Human iPS Cell Boost Supplement could be readily expanded for over 30 passages. Human iPS cells displayed the morphology characteristic of human ESCs, had a normal karyotype, and stained positive for pluripotent markers.
Use of the polycistronic lentiviral expression cassette in combination with small molecules provides a convenient platform for screening small molecules that enhance reprogramming efficiency with the eventual goal of generating iPS cells without genetic modification of the genome.
iPS cells have the potential to reshape the research and clinical landscape. Use of these cells for disease modeling and drug and toxicity screening can help overcome the limitations of current methods, enable construction of human models of complex diseases, and reveal important insights that can lead to a more personalized approach to medicine. Methods to improve the efficiency and kinetics of reprogramming human somatic cells into iPS cells will accelerate the application of these cells in both the research and clinical settings.