Biomedical Applications of Supramolecular Materials in the Controllable Delivery of Steroids

Nanomanipulation of Ligand Nanogeometry Modulates Integrin/Clathrin-Mediated Adhesion and Endocytosis of Stem Cells

Nanosubstrate engineering can be a biomechanical approach for modulating stem cell differentiation in tissue engineering. However, the study of the effect of clathrin-mediated processes on manipulating this behavior is unexplored. Herein, we develop integrin-binding nanosubstrates with confined nanogeometries that regulate clathrin-mediated adhesion- or endocytosis-active signaling pathways for modulating stem fates. Isotropically presenting ligands on the nanoscale enhances the expression of clathrin in cells, thereby facilitating uptake of dexamethasone-loaded nanoparticles (NPs) to boost osteogenesis of stem cells. In contrast, anisotropic ligand nanogeometry suppresses this clathrin-mediated NP entry by strengthening the association between clathrin and adhesion spots to reinforce mechanotransduced signaling, which can be abrogated by the pharmacological inhibition of clathrin. Meanwhile, inhibiting focal adhesion formation hinders cell spreading and enables a higher endocytosis efficiency. Our findings reveal the crucial roles of clathrin in both endocytosis and mechanotransduction of stem cells and provide the parameter of ligand nanogeometry for the rational design of biomaterials for tissue engineering.

Supramolecular detoxification of nitrogen mustard via host-guest encapsulation by carboxylatopillar[5]arene

Nitrogen mustard (NM), a kind of alkylating agent similar to sulfur mustard, remains a threat to public health. However, there is nearly no satisfactory antidote for nitrogen mustard. Herein, we developed a supramolecular antidote to nitrogen mustard through efficient complexation of NM by carboxylatopillar[5]arene potassium salts (CP[5]AK). The cavity of methoxy pillar[5]arene (P5A) is sufficient to encapsulate NM with an association constant of 1.27 × 10² M^-1, which was investigated by ¹H NMR titration, density functional theory studies and independent gradient model studies. NM degrades to the reactive aziridinium salt (2) in the aqueous phase which irreversibly alkylates DNA and proteins, causing severe tissue damage. Considering the size/charge matching with toxic intermediate 2, water-soluble CP[5]AK was selected to encapsulate the toxic aziridinium salt (2), resulting in a high association constant of 4.10 × 10⁴ M^-1. The results of protection experiments of guanosine 5'-monophosphate (GMP) by CP[5]AK indicated that the formation of a complex could effectively inhibit the alkylation of DNA. Besides, in vitro and in vivo experiments also indicated that the toxicity of the aziridinium salt (2) is inhibited with the formation of a stable host-guest complex, and CP[5]AK has a good therapeutic effect on the damage caused by NM. This study provides a new mechanism and strategy for the treatment of NM exposure-induced skin injuries.

The Role of Glucocorticoids in Inflammatory Diseases

For more than 70 years, glucocorticoids (GCs) have been a powerful and affordable treatment option for inflammatory diseases. However, their benefits do not come without a cost, since GCs also cause side effects. Therefore, strong efforts are being made to improve their therapeutic index. In this review, we illustrate the mechanisms and target cells of GCs in the pathogenesis and treatment of some of the most frequent inflammatory disorders affecting the central nervous system, the gastrointestinal tract, the lung, and the joints, as well as graft-versus-host disease, which often develops after hematopoietic stem cell transplantation. In addition, an overview is provided of novel approaches aimed at improving GC therapy based on chemical modifications or GC delivery using nanoformulations. GCs remain a topic of highly active scientific research despite being one of the oldest class of drugs in medical use.