Direct Conversion of Normal and Alzheimer’s Disease Human Fibroblasts into Neuronal Cells by Small Molecules

Abstract

Neuronal conversion from human fibroblasts can be induced by lineage-specific transcription factors; however, the introduction of ectopic genes limits the therapeutic applications of such induced neurons (iNs). Here, we report that human fibroblasts can be directly converted into neuronal cells by a chemical cocktail of seven small molecules, bypassing a neural progenitor stage. These human chemical-induced neuronal cells (hciNs) resembled hiPSC-derived neurons and human iNs (hiNs) with respect to morphology, gene expression profiles, and electrophysiological properties. This approach was further applied to generate hciNs from familial Alzheimer's disease patients. Taken together, our transgene-free and chemical-only approach for direct reprogramming of human fibroblasts into neurons provides an alternative strategy for modeling neurological diseases and for regenerative medicine.

Out with the Old, in with the New… Strategies Based on Stem Cells to Design New Models of Alzheimer’s Disease

“…On the contrary, no accumulation of tau protein was observed in this type of FAD-derived neurons, revealing that at least for that genotype this protein may not be the main cause of ailment [12,15,20]. Indeed, some studies have showed that iNs and iPSCs-derived neurons from FAD patient fibroblasts had an increased Aβ42/Aβ40 ratio that resembles that observed in AD brains [10,21,22]. Similarly, human iNs from familial AD patients recapitulated the pathology of altered processing and aberrant endosomal localization of APP as well as increased production of Aβ peptides [23].…”

“…In this sense the use of small molecules seems to overcome those technical drawbacks being capable of converting human fibroblasts into neurons with a cocktail of small molecules supplemented with chemicals known to promote the differentiation of neural progenitors into neurons [9]. iNs produced by this cocktail possess typical functional hallmarks of neurons [10]. Recently, the application of stem cell research to neurodegenerative disorders is rapidly increasing, not only for cell replacement therapy [11] but also as potential models of the malady in vitro [12,13] contributing to improve knowledge of the cellular and molecular mechanisms of neurodegeneration and innovative drug discovery such as AD.…”

Direct neuronal reprogramming: learning from and for development

“…Strikingly, manipulation of these and other pathways is indeed sufficient to convert fibroblasts (mouse and human) and astrocytes (human) into neurons (Hu et al, 2015;Zhang et al, 2015).…”

“…Neuronal conversion of human astrocytes and fibroblasts mediated by small molecules seems to require sequential phases of reprogramming, or a first phase of neuronal fate induction followed by a second phase of neuronal maturation (Table 1; Hu et al, 2015;Zhang et al, 2015). This strict order suggests some degree of organization in the molecular cascades involved in reprogramming that may recapitulate a developmental programme.…”

Cell sources for regenerative medicine of the liver and endoderm organs: strategies and perspectives

“…In keeping, the small molecule-based reprogramming has attracted much interest due to its safety and efficiency in controlling cell fates (12); this methodology has been successfully used for fibroblast reprogramming into iPS or neurons (13). In this context, the recent paper by Wang et al described a novel approach to generate human induced endodermal progenitor cells (hiEndoPCs); the lineage reprogramming of gastrointestinal epithelial cells was obtained using a cocktail of defined small molecules in association with the support of tissuespecific mesenchymal feeders (1).…”