Abstract
Human induced pluripotent stem cells (hiPSCs) are capable of differentiating into any cell type and provide significant advances to cell therapy and regenerative medicine. However, the current protocol for hiPSC generation is relatively inefficient and often results in many partially reprogrammed colonies, which increases the cost and reduces the applicability of hiPSCs. Biophysical stimulation, in particular from tuning cell-surface interactions, can trigger specific cellular responses that could in turn promote the reprogramming process. In this study, human fibroblasts were reprogrammed into hiPSCs using a feeder-free system and episomal vectors using novel substrates based on binary colloidal crystals (BCCs). BCCs are made from two different spherical particle materials (Si and PMMA) ranging in size from nanometers to micrometers that self-assemble into hexagonal close-packed arrays. Our results show that the BCCs, particularly those made from a crystal of 2 μm Si and 0.11 μm PMMA particles (2SiPM) facilitate the reprogramming process and increase the proportion of fully reprogrammed hiPSC colonies, even without a vitronectin coating. Subsequent isolation of clonal hiPSC lines demonstrates that they express pluripotent markers (OCT4 and TRA-1-60). This proof-of-concept study demonstrates that cell reprogramming can be improved on substrates where surface properties are tailored to the application.
Highlights
Cell culture conditions using the chemically defined E7 Medium combined with vitronectin (VN)-coated surfaces have greatly improved the feasibility of reprogramming and eliminated variations associated with feeder cells[10]
From the scanning electron microscopy (SEM) and atomic force microscopy (AFM) images (Fig. 2b,c), binary colloidal crystals (BCCs) were composed of large Si particles arranged in a hcp structure surrounded by small PMMA particles, which act as a glue to stabilize the structure after partial melting
We have shown previously that the criteria for using alkaline phosphatase (AP) expression coupled with human embryonic stem cell (hESC) morphology represents a reliable method to quantify reprogramming efficiency, with similar accuracy to quantification based on TRA-1-60 expression (Supplementary Fig. 1)[20]
Summary
Cell culture conditions using the chemically defined E7 Medium combined with vitronectin (VN)-coated surfaces have greatly improved the feasibility of reprogramming and eliminated variations associated with feeder cells[10]. Downing et al first reported that the surface topography of a cell culture substrate, in the form of parallel microgrooves or nanofibers, can replace the effects of small-molecule epigenetic modifiers and significantly improve reprogramming efficiency of mouse fibroblasts into iPSCs13. They postulate that a mechano-modulation effect of the substrate topography can modulate the epigenetic state of the cells. The symmetry of the surface topography can be modulated using different ratios of colloids in suspension, and the topography can be varied from random to highly ordered All these advantages support the feasibility of using BCCs as the generation cell culture tools, and potentially as a surface modification strategy for applications in regenerative medicine. The aim of this study was to improve cellular reprogramming processes by using complex surface topographies and chemistries that can be manufactured
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
