Supragel-mediated efficient generation of pancreatic progenitor clusters and functional glucose-responsive islet-like clusters

Although several synthetic hydrogels with defined stiffness have been developed to facilitate the proliferation and maintenance of human pluripotent stem cells(hPSCs),the influence of biochemical cues in lineage-specific differentiation and functional cluster formation has been rarely reported.Here,we present the application of Supragel,a supramolecular hydrogel formed by synthesized biotinylated peptides,for islet-like cluster differentiation.We observed that Supragel,with a peptide concentration of 5 mg/mL promoted spontaneous hPSCs formation into uniform clusters,which is mainly attributable to a supporting stiffness of∼1.5 kPa as provided by the Supragel matrix.Supragel was also found to interact with the hPSCs and facilitate endodermal and subsequent insulin-secreting cell differentiation,partially through its components:the sequences of RGD and YIGSR that interacts with cell membrane molecules of integrin receptor.Compared to Matrigel and suspension culturing conditions,more efficient differentiation of the hPSCs was also observed at the stages 3 and 4,as well as the final stage toward generation of insulin-secreting cells.This could be explained by 1)suitable average size of the hPSCs clusters cultured on Supragel;2)appropriate level of cell adhesive sites provided by Supragel during differentiation.It is worth noting that the Supragel culture system was more tolerance in terms of the initial seeding densities and less demanding,since a standard static cell culture condition was sufficient for the entire differentiation process.Our observations demonstrate a positive role of Supragel for hPSCs differentiation into islet-like cells,with additional potential in facilitating germ layer differentiation.

A SupraGel for efficient production of cell spheroids

Cell spheroids are markedly more representative of the native tissue and the in vivo environment than traditional two-dimensional(2D)cultured cells,thus offering tremendous potential in cell biology research,tissue engineering,and drug screening.Therefore,it is crucial to develop materials and methods for efficient production of cell spheroids.However,currently developed materials,including natural and synthetic hydrogels,present drawbacks,such as undefined ingredients and imperfect biocompatibility,which hinder their widespread application.In this study,we have rationally designed biotinylated peptides that can self-assemble into supramolecular hydrogels(termed SupraGel)for 3D cell culture.The introduction of one D-amino acid in the peptide may decrease cell-matrix interactions,thus facilitating spontaneous cell spheroid formation.Two cancer cell lines,MCF-7 and 4T1,and intestinal stem cells(ISCs)can efficiently divide into cell spheroids when cultured in SupraGel.The reversible shear-thinning and recovery behavior of SupraGel is highly suitable for live-cell embedding and cell spheroid harvesting.The mechanical properties of SupraGel can be easily tuned by adjusting the peptide concentration,thus enabling its suitability for the 3D culture of diverse cell spheroids.We envision the significant potential of our SupraGel for applications in cell therapy,regenerative medicine,and drug screening.

Tandem Molecular Self-Assembly Selectively Inhibits Lung Cancer Cells by Inducing Endoplasmic Reticulum Stress

The selective formation of nanomaterials in cancer cells and tumors holds great promise for cancer diagnostics and therapy.Until now,most strategies rely on a single trigger to control the formation of nanomaterials in situ.The combination of two or more triggers may provide for more sophisticated means of manipulation.In this study,we rationally designed a molecule(Comp.1)capable of responding to two enzymes,alkaline phosphatase(ALP),and reductase.Since the A549 lung cancer cell line showed elevated levels of extracellular ALP and intracellular reductase,we demonstrated that Comp.1 responded in a stepwise fashion to those two enzymes and displayed a tandem molecular self-assembly behavior.The selective formation of nanofibers in the mitochondria of the lung cancer cells led to the disruption of the mitochondrial membrane,resulting in an increased level of reactive oxygen species(ROS)and the release of cytochrome C(Cyt C).ROS can react with proteins,resulting in endoplasmic reticulum(ER)stress and the unfolded protein response(UPR).This severe ER stress led to disruption of the ER,formation of vacuoles,and ultimately,apoptosis of the A549 cells.Therefore,Comp.1 could selectively inhibit lung cancer cells in vitro and A549 xenograft tumors in vivo.Our study provides a novel strategy for the selective formation of nanomaterials in lung cancer cells,which is powerful and promising for the diagnosis and treatment of lung cancer.