Effects of mechanical stimulation on the reprogramming of somatic cells into human-induced pluripotent stem cells

Abstract

BackgroundMechanical stimuli play important roles in the proliferation and differentiation of adult stem cells. However, few studies on their effects on induced pluripotent stem cells (iPSCs) have been published.MethodsHuman dermal fibroblasts were seeded onto flexible membrane-bottom plates, and infected with retrovirus expressing the four reprogramming factors OCT4, SOX2, KLF, and c-MYC (OSKM). The cells were subjected to equiaxial stretching (3% or 8% for 2, 4, or 7 days) and seeded on feeder cells (STO). The reprogramming into iPSCs was evaluated by the expression of pluripotent markers, in vitro differentiation into three germ layers, and teratoma formation.ResultsEquiaxial stretching enhanced reprogramming efficiency without affecting the viral transduction rate. iPSCs induced by transduction of four reprogramming factors and application of equiaxial stretching had characteristics typical of iPSCs in terms of pluripotency and differentiation potentials.ConclusionsThis is the first study to show that mechanical stimuli can increase reprogramming efficiency. However, it did not enhance the infection rate, indicating that mechanical stimuli, defined as stretching in this study, have positive effects on reprogramming rather than on infection. Additional studies should evaluate the mechanism underlying the modulation of reprogramming of somatic cells into iPSCs.

Orchestrating stem cell fate: Novel tools for regenerative medicine

“…In addition, radio electric conveyed fields were sufficient to induce the neurogenic phenotype in PC12 cells, a model for dopaminergic neuron studies[76]. Finally, concerning cell reprogramming, several authors have shown that mechanical stimuli such as equiaxial stretching have an important role in reprogramming somatic cells into iPSCs, with the formation of a great number of iPSC colonies without using common viral mediated gene transduction[77]. These findings showed the prominence of physical stimuli in opening up new strategies for cell manipulation and regenerative medicine[78,79].…”

Unchain My Heart: Integrins at the Basis of iPSC Cardiomyocyte Differentiation

“…Reprogramming involves three sequential steps: initiation, stabilization, and maturation [106]. Indeed, molecular mediators, e.g., microRNA, or biophysical cues, e.g., nanotopography, can supplement or replace some of the classical reprogramming factors commonly used to enhance reprogramming efficiency [107–113].…”

“…Mechanical stimulation has been demonstrated to regulate FA assembly, modulating the downstream pathways affecting cardiomyogenesis [246–249]. Based on this assumption, several methods have been described for the application of controlled mechanical stimulation (i.e., temporal, spatial, and amplitude), some of them aiming to verify the positive impact of integrin-mediated adhesion pathways on iPSC reprogramming [113] and differentiation [250, 251]. Although far from being exhaustively described, the pathways seem to be regulated by the change in FA density and local conformation [252], followed by impacting cytoskeleton rearrangement [56], finally regulating cardiomyocyte maturity, e.g., cell-cell contact, sarcomeric structure, and electrical activity.…”

A high throughput screening system for studying the effects of applied mechanical forces on reprogramming factor expression

“…However, in other studies, mechanical strain reduced the expression of pluripotency transcription factors and signaling pathways related to pluripotency in iPSCs 23 . Mechanical stretch also enhanced the reprograming of cells treated with retrovirus-delivered pluripotency transcription factors without altering the efficiency of viral transduction 24 . Other studies have linked alterations in pluripotency to changes in cell shape or substrate stiffness 25 – 27 .…”