Nanoprobe-mediated precise imaging and therapy of glioma

Biomimetic Nanocomposites for Glioma Imaging and Therapy

Glioma, the most common primary brain tumor, is highly invasive and grows rapidly. As such, the survival of glioma patients is relatively short, highlighting the vital importance of timely diagnosis and treatment of glioma. However, the blood brain barrier (BBB) and the non-targeting delivery systems of contrast agents and drugs greatly hinder the effective glioma imaging and therapy. Fortunately, in recent years, investigators have constructed various biomimetic delivery platforms utilizing the exceptional advantages of biomimetic nanocomposites, such as immune evasion, homologous targeting ability, and BBB penetrating ability, to achieve efficient and precise delivery of substances to glioma sites for improved diagnosis and treatment. In this concept, we present the application of these biomimetic nanocomposites in fluorescence imaging (FI), magnetic resonance imaging (MRI), and multi-modal imaging, as well as in chemotherapy, phototherapy, and combined therapy for glioma. Lastly, we provide our perspective on this research field.

A D-Y Shaped Neuropeptide Y Mimetic Peptide-Dye Self-Assembly with Maximal Emission Beyond 1300 nm and Glioma Mitochondrial Activity Modulation

Neuropeptide Y (NPY), as one of the most abundant neuropeptides known, is widely distributed in the central and peripheral nervous system. However, most of the reported NPY-mimetic peptides are hard to cross the blood-brain barrier, target glioma mitochondria, and achieve self-assembly nanostructure in situ. Here, based on the α-helix structure of the novel chiral NPY-mimetic peptides D/L NPY(14), a Y-shaped peptide is designed with the sequences that can be recognized by enterokinase and achieved nanofibers conversion in glioma cell mitochondria. Coupling the Y-shaped NPY-mimetic peptide with the NIR-II fluorophore IR1048, a red-shifting of the fluorescence spectrum beyond 1300 nm is achieved through self-assembly. After the self-assembly in glioma mitochondria, the formed nanofibers can promote intracellular mitochondrial ROS production and extend the NIR-II fluorescence imaging time to at least 7 days in vivo. This work for the first time endows the self-assembly of α-helical-based chiral NPY-mimetic peptides, providing a novel strategy for glioma subcellular regulation enhanced antitumor treatment guided by NIR-II fluorescence imaging.

HECW1 induces NCOA4-regulated ferroptosis in glioma through the ubiquitination and degradation of ZNF350

Tumor suppression by inducing NCOA4-mediated ferroptosis has been shown to be feasible in a variety of tumors, including gliomas. However, the regulatory mechanism of ferroptosis induced by NCOA4 in glioma has not been studied deeply. HECW1 and ZNF350 are involved in the biological processes of many tumors, but their specific effects and mechanisms on glioma are still unclear. In this study, we found that HECW1 decreased the survival rate of glioma cells and enhanced iron accumulation, lipid peroxidation, whereas ZNF350 showed the opposite effect. Mechanistically, HECW1 directly regulated the ubiquitination and degradation of ZNF350, eliminated the transcriptional inhibition of NCOA4 by ZNF350, and ultimately activated NCOA4-mediated iron accumulation, lipid peroxidation, and ferroptosis. We demonstrate that HECW1 induces ferroptosis and highlight the value of HECW1 and ZNF350 in the prognostic evaluation of patients with glioma. We also elucidate the mechanisms underlying the HECW1/ZNF350/NCOA4 axis and its regulation of ferroptosis. Our findings enrich the understanding of ferroptosis and provide potential treatment options for glioma patients.

Band Gap Engineering Improves Three-Photon Luminescence of Quantum Dots for Deep Brain Imaging

Three-photon fluorescence microscopy (3PFM) has emerged as a promising tool in monitoring the structures and functions of the brain. Compared to the various imaging technologies, 3PFM enables a deep-penetrating depth attributed to tighter excitation confinement and suppressed photon scattering. However, the shortage of three-photon probes with a large absorption cross section (σ₃) substantially limits its uses. Herein, CdSe/CdS/ZnS quantum dots (QDs) with enhanced 3PF performance were synthesized via the band gap engineering strategy. The introduction of a CdS interlayer with optimized thickness between the emitting CdSe core and the ZnS shell significantly enhanced the 3P absorption cross section of QDs, which originated from the intrinsic piezoelectric polarization effect and the change of the core/shell structure from type-I to quasi-type-II. In addition, the outer ZnS layer compensated the poor electronic passivation of CdS, providing a high level of passivation for the improvement of quantum yield as well as the 3P action cross section of QDs. Under the excitation of a 1600 nm femtosecond laser, PEGylated CdSe/CdS/ZnS QDs were used for in vivo 3PFM imaging of cerebral vessels with high resolution. A tiny capillary with a diameter of 0.8 μm could be resolved at the imaging depth of 1550 μm in a mouse brain with an opened skull. A penetration depth of 850 μm beneath the skull was also achieved using a mouse model with an intact skull.

Controlling Disassembly of Paramagnetic Prodrug and Photosensitizer Nanoassemblies for On-Demand Orthotopic Glioma Theranostics

Controlling delivery and release of therapeutic agents to accomplish on-demand synergistic therapy of orthotopic gliomas is desired but challenging. Here, we report a glioma targeting and redox activatable theranostic nanoprobe (Co-NP-RGD_1/1) for magnetic resonance (MR) and fluorescence (FL) bimodal imaging-guided on-demand synergistic chemotherapy/photodynamic therapy (Chemo-PDT) of orthotopic gliomas. Co-NP-RGD_1/1 is formed via molecular coassembly of two paramagnetic and fluorogenic small-molecule probes CPT-RGD and PPa-RGD at an optimized molar ratio of 1/1, which shows a high longitudinal relaxivity (r₁ = 17.0 ± 0.6 mM^-1 s^-1, 0.5 T) but weak FL emissions and low Chemo-PDT activity. Upon reduction by endogenous glutathione (GSH), Co-NP-RGD_1/1 disassemble and release small molecules 2-RGD, chemodrug camptothecin (CPT), and near-infrared (NIR) photosensitizer (PS) PPa-SH that further binds to endogenous albumin to form PPa-SH-albumin complex, allowing to turn on FL, chemotherapeutic efficacy, and PDT activity for synergistic Chemo-PDT of orthotopic U87MG or U251 gliomas in living mice. Moreover, Co-NP-RGD_1/1 can also allow noninvasive detection and monitoring of orthotopic brain tumor growth via FL and MR imaging. Findings suggest the potential of cascade coassembly and stimuli-controlled intracellular disassembly strategy for constructing targeted and activatable nanoagents for improving combinational cancer theranostics.

Blood-brain barrier penetrating carbon dots with intrinsic anti-inflammatory and drug-loading properties

The blood-brain barrier (BBB) is the major obstacle limiting the reach of therapeutic drugs into the brain. Herein, an aspirin-based anti-inflammatory replenisher (aspCD) was fabricated by carbonizing aspirin to deliver drugs into the brain visually. The as-prepared aspCD combined the BBB-penetrating and anti-inflammatory effects of aspirin with the fluorescent and drug-loading properties of carbon dots (CDs), thereby delivering therapeutic drugs into the brain and acting as imaging agent as well as anti-inflammatory replenisher. In vivo experiments of mice and zebrafish revealed that fluorescence aspCD could effectively penetrate BBB. In vitro and in vivo inflammatory models demonstrated that aspCD could be regarded as an excellent anti-inflammatory replenisher. In addition, as a functional carrier, aspCD was proved to be capable of loading drugs with different polarity. In summary, carbonization of active precursors (therapeutic drugs) into CDs could be a promising strategy to achieve the loading and visualization of drugs as well as the retainment of their biological activities.

Manganese-based hollow nanoplatforms for MR imaging-guided cancer therapies

Theranostic nanoplatforms integrating diagnostic and therapeutic functions have received considerable attention in the past decade. Among them, hollow manganese (Mn)-based nanoplatforms are superior since they combine the advantages of hollow structures and the intrinsic theranostic features of Mn²⁺. Specifically, the hollow cavity can encapsulate a variety of small-molecule drugs, such as chemotherapeutic agents, photosensitizers and photothermal agents, for chemotherapy, photodynamic therapy (PDT) and photothermal therapy (PTT), respectively. After degradation in the tumor microenvironment (TME), the released Mn²⁺ is able to act simultaneously as a magnetic resonance (MR) imaging contrast agent (CA) and as a Fenton-like agent for chemodynamic therapy (CDT). More importantly, synergistic treatment outcomes can be realized by reasonable and optimized design of the hollow nanosystems. This review summarizes various Mn-based hollow nanoplatforms, including hollow Mn_xO_y, hollow matrix-supported Mn_xO_y, hollow Mn-doped nanoparticles, hollow Mn complex-based nanoparticles, hollow Mn-cobalt (Co)-based nanoparticles, and hollow Mn-iron (Fe)-based nanoparticles, for MR imaging-guided cancer therapies. Finally, we discuss the potential obstacles and perspectives of these hollow Mn-based nanotheranostics for translational applications.

Identification of Neural Progenitor Cell-Associated Chemoradiotherapy Resistance Gene Set (ARL4C, MSN, TNFAIP6) for Prognosis of Glioma

BACKGROUND

Glioma is the most common malignant intracranial tumor with high lethality. Despite surgery combined with chemoradiotherapy, the prognosis for patients with glioma remains poor. This is primarily due to acquired chemoradiotherapy resistance. Therefore, to improve the prognosis of glioma, further study into the mechanism of chemoradiotherapy resistance is needed.

OBJECTIVE

This study aimed to (1) evaluate the prognosis of patients with glioma by using a prognostic risk score model constructed by chemoradiotherapy resistance genes, (2) provide new targets and directions for precise treatment of glioma, and (3) discuss the tumor heterogeneity of tumor cells.

METHODS

According to therapy class and overall survival (OS), we identified 53 genes associated with glioma chemoradiotherapy resistance in The Cancer Genome Atlas Glioblastoma (TCGA GBM) database. Considering the improtant role of chemoradiotherapy resistance-related genes in the prognosis of glioma, we preliminarily screened and identified vital prognostic factors among these genes by using Cox regression model of absolute contraction and selection operators in the TCGA GBM lower-grade glioma (TCGA GBMLGG) dataset. Next, the heterogeneity of the chemoradiotherapy resistance-associated genes in different glioma cells was revealed by single-cell sequencing in the GSE117891 cohort.

RESULTS

A prognostic risk score model consisting of three genes (ARL4C, MSN, TNFAIP6) was constructed. The expression of this model was high in glioma neural progenitor cells (NPCs) and low in glioma oligodendrocytes. The OS rates were significantly lower in the high- vs low-risk group.

CONCLUSION

Our 3 gene risk score complements current glioma diagnosis and provides a novel insight into chemoradiotherapy resistance mechanisms for the prognosis of patients with glioma.

Recent development of contrast agents for magnetic resonance and multimodal imaging of glioblastoma

Glioblastoma (GBM) as the most common primary malignant brain tumor exhibits a high incidence and degree of malignancy as well as poor prognosis. Due to the existence of formidable blood–brain barrier (BBB) and the aggressive growth and infiltrating nature of GBM, timely diagnosis and treatment of GBM is still very challenging. Among different imaging modalities, magnetic resonance imaging (MRI) with merits including high soft tissue resolution, non-invasiveness and non-limited penetration depth has become the preferred tool for GBM diagnosis. Furthermore, multimodal imaging with combination of MRI and other imaging modalities would not only synergistically integrate the pros, but also overcome the certain limitation in each imaging modality, offering more accurate morphological and pathophysiological information of brain tumors. Since contrast agents contribute to amplify imaging signal output for unambiguous pin-pointing of tumors, tremendous efforts have been devoted to advances of contrast agents for MRI and multimodal imaging. Herein, we put special focus on summary of the most recent advances of not only MRI contrast agents including iron oxide-, manganese (Mn)-, gadolinium (Gd)-, ¹⁹F- and copper (Cu)-incorporated nanoplatforms for GBM imaging, but also dual-modal or triple-modal nanoprobes. Furthermore, potential obstacles and perspectives for future research and clinical translation of these contrast agents are discussed. We hope this review provides insights for scientists and students with interest in this area.