Dual-targeting and microenvironment-responsive micelles as a gene delivery system to improve the sensitivity of glioma to radiotherapy

Dbait is a small double-stranded DNA molecule that has been utilized as a radiosensitizer to enhance the sensitivity of glioma to radiotherapy(RT). However, there is no effective drug delivery system to effectively overcome the blood–brain barrier(BBB). The aim of this study was to develop a gene delivery system by using the BBB and glioma dual-targeting and microenvironment-responsive micelles(ch-Kn(s-s)R8-An) to deliver Dbait into glioma for RT. Angiopep-2 can target the low-density lipoprotein receptor-related protein-1(LRP1) that is overexpressed on brain capillary endothelial cells(BCECs) and glioma cells. In particular, due to upregulated matrix metalloproteinase 2(MMP-2) in the tumor microenvironment, we utilized MMP-2-responsive peptides as the enzymatically degradable linkers to conjugate angiopep-2. The results showed that ch-Kn(s-s)R8-An micelles maintained a reasonable size(80–160 nm) with a moderate distribution and a decreased mean diameter from the cross-linking as well as exhibited low critical micelle concentration(CMC) with positive surface charge, ranging from 15 to40 mV. The ch-K5(s-s)R8-An/pEGFP showed high gene transfection efficiency in vitro, improved uptake in glioma cells and good biocompatibility in vitro and in vivo. In addition, the combination of ch-K5(s-s)R8-An/Dbait with RT significantly inhibited the growth of U251 cells in vitro. Thus, ch-K5(s-s)R8-An/Dbait may prove to be a promising gene delivery system to target glioma and enhance the efficacy of RT on U251 cells.

Targeted delivery of a STING agonist to brain tumors using bioengineered protein nanoparticles for enhanced immunotherapy

Immunotherapy is emerging as a powerful tool for combating many human diseases.However,the application of this life-saving treatment in serious brain diseases,including glioma,is greatly restricted.The major obstacle is the lack of effective technologies for transporting therapeutic agents across the blood-brain barrier(BBB)and achieving targeted delivery to specific cells once across the BBB.Ferritin,an iron storage protein,traverses the BBB via receptor-mediated transcytosis by binding to transferrin receptor 1(TfR1)overexpressed on BBB endothelial cells.Here,we developed bioengineered ferritin nanoparticles as drug delivery carriers that enable the targeted delivery of a small-molecule immunomodulator to achieve enhanced immunotherapeutic efficacy in an orthotopic glioma-bearing mouse model.We fused different glioma-targeting moieties on self-assembled ferritin nanoparticles via genetic engineering,and RGE fusion protein nanoparticles(RGE-HFn NPs)were identified as the best candidate.Furthermore,RGE-HFn NPs encapsulating a stimulator of interferon genes(STING)agonist(SR717@RGE-HFn NPs)maintained stable self-assembled structure and targeting properties even after traversing the BBB.In the glioma-bearing mouse model,SR717@RGE-HFn NPs elicited a potent local innate immune response in the tumor microenvironment,resulting in significant tumor growth inhibition and prolonged survival.Overall,this biomimetic brain delivery platform offers new opportunities to overcome the BBB and provides a promising approach for brain drug delivery and immunotherapy in patients with glioma.