Helping Induced hPSCs Clean Up Their Act

Amphiregulin promotes hair regeneration of skin-derived precursors via the PI3K and MAPK pathways

Objectives

There are significant clinical challenges associated with alopecia treatment, including poor efficiency of related drugs and insufficient hair follicles (HFs) for transplantation. Skin‐derived precursors (SKPs) exhibit great potential as stem cell‐based therapies for hair regeneration; however, the proliferation and hair‐inducing capacity of SKPs gradually decrease during culturing.

Materials and Methods

We describe a 3D co‐culture system accompanied by kyoto encyclopaedia of genes and genomes and gene ontology enrichment analyses to determine the key factors and pathways that enhance SKP stemness and verified using alkaline phosphatase assays, Ki‐67 staining, HF reconstitution, Western blot and immunofluorescence staining. The upregulated genes were confirmed utilizing corresponding recombinant protein or small‐interfering RNA silencing in vitro, as well as the evaluation of telogen‐to‐anagen transition and HF reconstitution in vivo.

Results

The 3D co‐culture system revealed that epidermal stem cells and adipose‐derived stem cells enhanced SKP proliferation and HF regeneration capacity by amphiregulin (AREG), with the promoted stemness allowing SKPs to gain an earlier telogen‐to‐anagen transition and high‐efficiency HF reconstitution. By contrast, inhibitors of the phosphoinositide 3‐kinase (PI3K) and mitogen‐activated protein kinase (MAPK) pathways downstream of AREG signalling resulted in diametrically opposite activities.

Conclusions

By exploiting a 3D co‐culture model, we determined that AREG promoted SKP stemness by enhancing both proliferation and hair‐inducing capacity through the PI3K and MAPK pathways. These findings suggest AREG therapy as a potentially promising approach for treating alopecia.

Safe scarless cassette-free selection of genome-edited human pluripotent stem cells using temporary drug resistance

An efficient gene-editing technique for use in human pluripotent stem cells (hPSCs) has great potential value in regenerative medicine, as well as in drug discovery based on isogenic human disease models. However, the extremely low efficiency of gene editing in hPSCs remains as a major technical hurdle. Previously, we demonstrated that YM155, a survivin inhibitor developed as an anti-cancer drug, induces highly selective cell death in undifferentiated hPSCs. In this study, we demonstrated that the high cytotoxicity of YM155 in hPSCs, which is mediated by selective cellular uptake of the drug, is due to the high expression of SLC35F2 in these cells. Knockout of SLC35F2 with CRISPR-Cas9, or depletion with siRNAs, made the hPSCs highly resistant to YM155. Simultaneous editing of a gene of interest and transient knockdown of SLC35F2 following YM155 treatment enabled the survival of genome-edited hPSCs as a result of temporary YM155 resistance, thereby achieving an enriched selection of clonal populations with gene knockout or knock-in. This precise and efficient genome editing approach took as little as 3 weeks and required no cell sorting or the introduction of additional genes, to be a more feasible approach for gene editing in hPSCs due to its simplicity.