Sheltering proteins from protease-mediated degradation and a de novo strategy for preventing acute liver injury

pH-Responsive Hexa-Histidine Metal Assembly (HmA) with Enhanced Biocatalytic Cascades as the Vehicle for Glucose-Mediated Long-Acting Insulin Delivery

Diabetes has been listed as one of the three major diseases that endanger human health. Accurately injecting insulin (Ins) depending on the level of blood glucose (LBG) is the standard treatment, especially controlling LBG in the long-term by a single injection. Herein, the pH-responsive hexa-histidine metal assembly (HmA) encapsulated with enzymes (GOx and CAT) and Ins (HmA@GCI) is engineered as the vehicle for glucose-mediated insulin delivery. HmA not only shows high proteins loading efficiency, but also well retained proteins activity and protect proteins from protease damage. Within HmA, the biocatalytic activities of enzymes and the efficiency of the cascade reaction between GOx and CAT are enhanced, leading to a super response to the change of LBG with insulin release and efficient clearance of harmful byproducts of GOx (H2 O2 ). In the treatment of diabetic mice, HmA@GCI reduces LBG to normal in half an hour and maintains for more than 5 days by a single subcutaneous injection, and nearly 24 days with four consecutive injections. During the test period, no symptoms of hypoglycemia and toxicity to tissues and organs are observed. These results indicate that HmA@GCI is a safe and long-acting hypoglycemic agent with prospective clinical application.

Efficient Delivery of Antibodies Intracellularly by Co-Assembly with Hexahistidine-Metal Assemblies (HmA)

PURPOSE

There has been a substantial global market for antibodies, which are based on extracellular targets. Binding intracellular targets by antibodies will bring new chances in antibody therapeutics and a huge market increase. We aim to evaluate the efficiency of a novel delivery system of His6-metal assembly (HmA) in delivering intracellular antibodies and biofunctions of delivered antibodies.

METHODS

In this study, the physicochemical properties of HmA@Antibodies generated through co-assembling with antibodies and HmA were well characterized by dynamic light scatter. The cytotoxicity of HmA@Antibodies was investigated by Cell Counting Kit-8 (CCK-8). The endocytic kinetics and lysosome escape process of HmA@Antibodies were studied by flow cytometry and fluorescent staining imaging, respectively. Compared to the commercialized positive control, the intracellular delivery efficiency by HmA@Antibodies and biofunctions of delivered antibodies were evaluated by fluorescent imaging and CCK-8.

RESULTS

Various antibodies (IgG, anti-β-tubulin and anti-NPC) could co-assemble with HmA under a gentle condition, producing nano-sized (~150 nm) and positively charged (~+30 eV) HmA@Antibodies particles with narrow size distribution (PDI ~ 0.15). HmA displayed very low cytotoxicity to divers cells (DCs, HeLa, HCECs, and HRPE) even after 96 h for the feeding concentration ≤100 μg mL-1, and fast escape from endosomes. In the case of delivery IgG, the delivery efficiency into alive cells of HmA was better than a commercial protein delivery reagent (PULSin). For cases of the anti-β-tubulin and anti-NPC, HmA showed comparable delivery efficiency to their positive controls, but HmA with ability to deliver these antibodies into alive cells was still superior to positive controls delivering antibodies into dead cells through punching holes.

CONCLUSION

Our results indicate that this strategy is a feasible way to deliver various antibodies intracellularly while preserving their functions, which has great potential in various applications and treating many refractory diseases by intracellular antibody delivery.