Direct reprogramming of mouse fibroblasts into hepatocyte-like cells by polyethyleneimine-modified nanoparticles through epigenetic activation of hepatic transcription factors

Abstract

Direct reprogramming without an intermediate pluripotent state has great therapeutic potential in regenerative medicine. Controlling lineage-specific transcription factors (TFs) expression can change cell fate and plasticity of somatic cells. However, traditional method of direct reprogramming using viral vector mediated gene delivery remains an obstacle for clinical application due to risk of tumorigenesis. Recently, nanomaterials have been reported to be more promising delivery systems to achieve this aim, but most of methods provide DNA-based reprogramming and the underlying mechanism of direct reprogramming remains poorly understood. Here, polyethyleneimine (PEI)-modified silica nanoparticles are developed as an efficient and safe protein transduction platform for delivering two key recombinant proteins of TFs for direct lineage reprogramming of mouse embryonic fibroblasts (MEFs) to functional induced hepatocyte-like cells (iHeps). Furthermore, the mechanisms involved in lineage reprogramming of MEFs into iHeps induced by mesoporous silica nanoparticle/polyethyleneimine/transcription factor (MSN/PEI/TF) nanocomplexes are elucidated. Epigenetic mechanistic investigations uncovered reinforced enrichment of activating marks (H3K4me3 and H3K9Ac) and loss of repressive marks (H3K27me3 and H3K9me3) at the promoters of hepatic TFs during direct hepatic reprogramming upon PEI-modified silica nanoparticles. Thus, this study provides proof of principle for silica-based nanoparticles as potentially viable and safe therapeutic strategies for direct reprogramming in regenerative medicine.