Photothermal Therapy for the Treatment of Glioblastoma: Potential and Preclinical Challenges

Hydrogel Applications in the Diagnosis and Treatment of Glioblastoma

Glioblastoma multiforme (GBM), a common malignant neurological tumor, has boundaries indistinguishable from those of normal tissue, making complete surgical removal ineffective. The blood-brain barrier (BBB) further impedes the efficacy of radiotherapy and chemotherapy, leading to suboptimal treatment outcomes and a heightened probability of recurrence. Hydrogels offer multiple advantages for GBM diagnosis and treatment, including overcoming the BBB for improved drug delivery, controlled drug release for long-term efficacy, and enhanced relaxation properties of magnetic resonance imaging (MRI) contrast agents. Hydrogels, with their excellent biocompatibility and customizability, can mimic the in vivo microenvironment, support tumor cell culture, enable drug screening, and facilitate the study of tumor invasion and metastasis. This paper reviews the classification of hydrogels and recent research for the diagnosis and treatment of GBM, including their applications as cell culture platforms and drugs including imaging contrast agents carriers. The mechanisms of drug release from hydrogels and methods to monitor the activity of hydrogel-loaded drugs are also discussed. This review is intended to facilitate a more comprehensive understanding of the current state of GBM research. It offers insights into the design of integrated hydrogel-based GBM diagnosis and treatment with the objective of achieving the desired therapeutic effect and improving the prognosis of GBM.

In Silico Approach to Model Heat Distribution of Magnetic Hyperthermia in the Tumoral and Healthy Vascular Network Using Tumor-on-a-Chip to Evaluate Effective Therapy

Glioblastoma multiforme (GBM) is the most severe form of brain cancer in adults, characterized by its complex vascular network that contributes to resistance to conventional therapies. Thermal therapies, such as magnetic hyperthermia (MHT), emerge as promising alternatives, using heat to selectively target tumor cells while minimizing damage to healthy tissues. The organ-on-a-chip can replicate this complex vascular network of GBM, allowing for detailed investigations of heat dissipation in MHT, while computational simulations refine treatment parameters. In this in silico study, tumor-on-a-chip models were used to optimize MHT therapy by comparing heat dissipation in normal and abnormal vascular networks, considering geometries, flow rates, and concentrations of magnetic nanoparticles (MNPs). In the high vascular complexity model, the maximum velocity was 19 times lower than in the normal vasculature model and 4 times lower than in the low-complexity tumor model, highlighting the influence of vascular complexity on velocity and temperature distribution. The MHT simulation showed greater heat intensity in the central region, with a flow rate of 1 µL/min and 0.5 mg/mL of MNPs being the best conditions to achieve the therapeutic temperature. The complex vasculature model had the lowest heat dissipation, reaching 44.15 °C, compared to 42.01 °C in the low-complexity model and 37.80 °C in the normal model. These results show that greater vascular complexity improves heat retention, making it essential to consider this heterogeneity to optimize MHT treatment. Therefore, for an efficient MHT process, it is necessary to simulate ideal blood flow and MNP conditions to ensure heat retention at the tumor site, considering its irregular vascularization and heat dissipation for effective destruction.

Iron Oxide Nanoparticles: Parameters for Optimized Photoconversion Efficiency in Synergistic Cancer Treatment

Photothermal therapy (PTT) can overcome cancer treatment resistance by enhancing the cell membrane permeability, facilitating drug accumulation, and promoting drug release within the tumor tissue. Iron oxide nanoparticles (IONPs) have emerged as effective agents for PTT due to their unique properties and biocompatibility. Approved for the treatment of anemia, as MRI contrast agents, and as magnetic hyperthermia mediators, IONPs also offer excellent light-to-heat conversion and can be manipulated using external magnetic fields for targeted accumulation in specific tissue. Optimizing parameters such as the laser wavelength, power density, shape, size, iron oxidation state, functionalization, and concentration is crucial for IONPs' effectiveness. In addition to PTT, IONPs enhance other cancer treatment modalities. They improve tumor oxygenation, enhancing the efficacy of radiotherapy and photodynamic therapy. IONPs can also trigger ferroptosis, a programmed cell death pathway mediated by iron-dependent lipid peroxidation. Their magneto-mechanical effect allows them to exert a mechanical force on cancer cells to destroy tumors, minimizing the damage to healthy tissue. This review outlines strategies for the management of the photothermal performance and PTT efficiency with iron oxide nanoparticles, as well as synergies with other cancer therapies.

A recent insight of applications of gold nanoparticles in glioblastoma multiforme therapy

The application of gold nanoparticles (AuNPs) in cancer therapy, particularly targeted therapy of glioblastoma multiforme (GBM), is an up-and-coming field of research that has gained much interest in recent years. GBM is a life-threatening malignant tumour of the brain that currently has a 95 % death rate with an average of 15 months of survival. AuNPs have proven to have wide clinical implications and compelling therapeutic potential in many researches, specifically in GBM treatment. It was found that the reason why AuNPs were highly desired for GBM treatment was due to their unique properties that diversified the applications of AuNPs further to include imaging, diagnosis, and photothermal therapy. These properties include easy synthesis, biocompatibility, and surface functionalization. Various studies also underscored the ability of AuNPs to cross the blood-brain-barrier and selectively target tumour cells while displaying no major safety concerns which resulted in better therapy results. We attempt to bring together some of these studies in this review and provide a comprehensive overview of safety evaluations and current and potential applications of AuNPs in GBM therapy that may result in AuNP-mediated therapy to be the new gold standard for GBM treatment.

Peptide-Hitchhiking for the Development of Nanosystems in Glioblastoma

Glioblastoma (GBM) remains the epitome of aggressiveness and lethality in the spectrum of brain tumors, primarily due to the blood-brain barrier (BBB) that hinders effective treatment delivery, tumor heterogeneity, and the presence of treatment-resistant stem cells that contribute to tumor recurrence. Nanoparticles (NPs) have been used to overcome these obstacles by attaching targeting ligands to enhance therapeutic efficacy. Among these ligands, peptides stand out due to their ease of synthesis and high selectivity. This article aims to review single and multiligand strategies critically. In addition, it highlights other strategies that integrate the effects of external stimuli, biomimetic approaches, and chemical approaches as nanocatalytic medicine, revealing their significant potential in treating GBM with peptide-functionalized NPs. Alternative routes of parenteral administration, specifically nose-to-brain delivery and local treatment within the resected tumor cavity, are also discussed. Finally, an overview of the significant obstacles and potential strategies to overcome them are discussed to provide a perspective on this promising field of GBM therapy.

Bacteria Synergized with PD-1 Blockade Enhance Positive Feedback Loop of Cancer Cells-M1 Macrophages-T Cells in Glioma

Cancer immunotherapy is an attractive strategy because it stimulates immune cells to target malignant cells by regulating the intrinsic activity of the immune system. However, due to lacking many immunologic markers, it remains difficult to treat glioma, a representative "cold" tumor. Herein, to wake the "hot" tumor immunity of glioma, Porphyromonas gingivalis (Pg) is customized with a coating to create an immunogenic tumor microenvironment and further prove the effect in combination with the immune checkpoint agent anti-PD-1, exhibiting elevated therapeutic efficacy. This is accomplished not by enhancing the delivery of PD-1 blockade to enhance the effect of immunotherapy, but by introducing bacterial photothermal therapy to promote greater involvement of M1 cells in the immune response. After reaching glioma, the bacteria further target glioma cells and M2 phenotype macrophages selectively, enabling precise photothermal conversion for lysing tumor cells and M2 phenotype macrophages, which thereby enhances the positive feedback loop of cancer cells-M1 macrophages-T cells. Collectively, the bacteria synergized with PD-1 blockade strategy may be the key to overcoming the immunosuppressive glioma microenvironment and improving the outcome of immunotherapy toward glioma.

Exploring the in vitro potential of royal jelly against glioblastoma and neuroblastoma: impact on cell proliferation, apoptosis, cell cycle, and the biomolecular content

Neuroblastoma and glioblastoma are the most commonly seen nervous system tumors, and their treatment is challenging. Relatively safe and easy acquisition of nutraceutical natural products make them suitable candidates for anticancer research. Royal jelly (RJ), a superfood, has many biological and pharmacological activities. This study was conducted to, for the first time, elucidate its anticancer efficiency, even in high doses, on neuroblastoma and glioblastoma cell lines through cell viability, apoptosis, cell cycle and biomolecular content evaluation. We performed experiments with RJ concentrations in the range of 1.25-10 mg mL-1 for 48 h. Cell viability assays revealed a notable cytotoxic effect of RJ in a concentration-dependent manner. Treatment with a high dose of RJ significantly increased the apoptotic cell population of both cell lines. Furthermore, we observed G0-G1 phase arrest in neuroblastoma cells but G2-M arrest in glioblastoma cells. All these cellular changes are closely associated with the alterations of the macromolecular makeup of the cells, such as decreased saturated lipid, protein, DNA and RNA amounts, protein conformational changes, decreased protein phosphorylation and increased protein carbonylation. These cellular changes are associated with RJ triggered-ROS formation. The clear segregation between the control and the RJ-treated groups proved these changes, obtained from the unsupervised and supervised chemometric analysis. RJ has good anticancer activity against nervous system cancers and could be safely used with current treatment strategies.

Advances in screening hyperthermic nanomedicines in 3D tumor models

Hyperthermic nanomedicines are particularly relevant for tackling human cancer, providing a valuable alternative to conventional therapeutics. The early-stage preclinical performance evaluation of such anti-cancer treatments is conventionally performed in flat 2D cell cultures that do not mimic the volumetric heat transfer occurring in human tumors. Recently, improvements in bioengineered 3D in vitro models have unlocked the opportunity to recapitulate major tumor microenvironment hallmarks and generate highly informative readouts that can contribute to accelerating the discovery and validation of efficient hyperthermic treatments. Leveraging on this, herein we aim to showcase the potential of engineered physiomimetic 3D tumor models for evaluating the preclinical efficacy of hyperthermic nanomedicines, featuring the main advantages and design considerations under diverse testing scenarios. The most recent applications of 3D tumor models for screening photo- and/or magnetic nanomedicines will be discussed, either as standalone systems or in combinatorial approaches with other anti-cancer therapeutics. We envision that breakthroughs toward developing multi-functional 3D platforms for hyperthermia onset and follow-up will contribute to a more expedited discovery of top-performing hyperthermic therapies in a preclinical setting before their in vivo screening.

Development of Hollow Gold Nanoparticles for Photothermal Therapy and Their Cytotoxic Effect on a Glioma Cell Line When Combined with Copper Diethyldithiocarbamate

Gold-based nanoparticles hold promise as functional nanomedicines, including in combination with a photothermal effect for cancer therapy in conjunction with chemotherapy. Here, we synthesized hollow gold nanoparticles (HGNPs) exhibiting efficient light absorption in the near-IR (NIR) region. Several synthesis conditions were explored and provided monodisperse HGNPs approximately 95-135 nm in diameter with a light absorbance range of approximately 600-720 nm. The HGNPs were hollow and the surface had protruding structures when prepared using high concentrations of HAuCl4. The simultaneous nucleation of a sacrificial AgCl template and Au nanoparticles may affect the resulting HGNPs. Diethyldithiocarbamate (DDTC) is metabolized from disulfiram and is a repurposed drug currently attracting attention. The chelation of DDTC with copper ion (DDTC-Cu) has been investigated for treating glioma, and here we confirmed the cytotoxic effect of DDTC-Cu towards rat C6 glioma cells in vitro. HGNPs alone were biocompatible and showed little cytotoxicity, whereas a mixture of DDTC-Cu and HGNPs was cytotoxic in a dose dependent manner. The temperature of HGNPs was increased by NIR-laser irradiation. The photothermal effect on HGNPs under NIR-laser irradiation resulted in cytotoxicity towards C6 cells and was dependent on the irradiation time. Photothermal therapy by HGNPs combined and DDTC-Cu was highly effective, suggesting that this combination approach hold promise as a future glioma therapy.

Plasmonic porous micro- and nano-materials based on Au/Ag nanostructures developed for photothermal cancer therapy: challenges in clinicalization

Photothermal therapy (PTT) has developed in recent decades as a relatively safe method for the treatment of cancers. Recently, various species of gold and silver (Au and Ag) nanostructures have been developed and investigated to achieve PTT due to their highly localized surface plasmon resonance (LSPR) effect. Concisely, the collective oscillation of electrons on the surface of Au and Ag nanostructures upon exposure to a specific wavelength (depending on their size and shape) and further plasmonic resonance leads to the heating of the surface of these particles. Hence, porous species can be equipped with tiny plasmonic ingredients that add plasmonic properties to therapeutic cargoes. In this case, a precise review of the recent achievements is very important to figure out to what extent plasmonic photothermal therapy (PPTT) by Au/Ag-based plasmonic porous nanomedicines successfully treated cancers with satisfactory biosafety. Herein, we classify the various species of LSPR-active micro- and nano-materials. Moreover, the routes for the preparation of Ag/Au-plasmonic porous cargoes and related bench assessments are carefully reviewed. Finally, as the main aim of this study, principal requirements for the clinicalization of Ag/Au-plasmonic porous cargoes and their further challenges are discussed, which are critical for specialists in this field.

Photothermal therapy of papillary thyroid cancer tumor xenografts with targeted thyroid stimulating hormone receptor antibody functionalized multiwalled carbon nanotubes

Multiwalled carbon nanotubes (MWCNTs) are being widely investigated in multiple biomedical applications including, and not limited to, drug delivery, gene therapy, imaging, biosensing, and tissue engineering. Their large surface area and aspect ratio in addition to their unique structural, optical properties, and thermal conductivity also make them potent candidates for novel hyperthermia therapy. Here we introduce thyroid hormone stimulating receptor (TSHR) antibody–conjugate–MWCNT formulation as an enhanced tumor targeting and light-absorbing device for the photoablation of xenografted BCPAP papillary thyroid cancer tumors. To ensure successful photothermal tumor ablation, we determined three key criteria that needed to be addressed: (1) predictive pre-operational modeling; (2) real-time monitoring of the tumor ablation process; and (3) post-operational follow-up to assess the efficacy and ensure complete response with minimal side effects. A COMSOL-based model of spatial temperature distributions of MWCNTs upon selected laser irradiation of the tumor was prepared to accurately predict the internal tumor temperature. This modeling ensured that 4.5W of total laser power delivered over 2 min, would cause an increase of tumor temperature above 45 ℃, and be needed to completely ablate the tumor while minimizing the damage to neighboring tissues. Experimentally, our temperature monitoring results were in line with our predictive modeling, with effective tumor photoablation leading to a significantly reduced post 5-week tumor recurrence using the TSHR-targeted MWCNTs. Ultimately, the results from this study support a utility for photosensitive biologically modified MWCNTs as a cancer therapeutic modality. Further studies will assist with the transition of photothermal therapy from preclinical studies to clinical evaluations.

Multi-charged nanoemulsion for photodynamic treatment of glioblastoma cell line in 2D and 3D in vitro models

Multi-charged nanoemulsions (NE) were designed to deliver Cannabidiol (CBD), Indocyanine green (ICG), and Protoporphyrin (PpIX) to treat glioblastoma (GBM) through Photodynamic Therapy (PDT). The phase-inversion temperature (PIT) method resulted in a highly stable NE that can be scaled easily, with a six-month shelf-life. We observed the quasi-spherical morphology of the nanoemulsions without any unencapsulated material and that 89% (± 5.5%) of the material was encapsulated. All physicochemical properties were within the expected range for a nanostructured drug delivery system, making these multi-charged nanoemulsions promising for further research and development. NE-PIC (NE-Protoporphyrin + Indocyanine + CBD) was easily internalized on GBM cells after three hours of incubation. Nanoemulsion (NE and NE-PIC) did not result in significant cytotoxicity, even for GBM or non-tumorigenic cell lines (NHF). Phototoxicity was significantly higher for the U87MG cell than the T98G cell when exposed to: visible (430 nm) and infrared (810 nm) laser light, with a difference of about 20%. From 50 mJ.cm-2, the viability of GBM cell lines decreases significantly, ranging from 65% to 85%. The NE-PIC was also effective for inhibiting cell proliferation into a 3D spheroidal GBM cell model, which is promising for mimicking the tumor cell environment. Irradiation at 810 nm was more effective in treating spheroid due to its deeper penetration in complex structures. NE-PIC has the potential as a drug delivery system for photoinactivation and photo diagnostic of GBM cell lines, taking advantage of the versatility of its active components.

Thermo-Chemical Resistance to Combination Therapy of Glioma Depends on Cellular Energy Level

Thermal therapy has been widely used in clinical tumor treatment and more recently in combination with chemotherapy, where the key challenge is the treatment resistance. The mechanism at the cellular level underlying the resistance to thermo-chemical combination therapy remains elusive. In this study, we constructed 3D culture models for glioma cells (i.e., 3D glioma spheres) as the model system to recapitulate the native tumor microenvironment and systematically investigated the thermal response of 3D glioma spheres at different hyperthermic temperatures. We found that 3D glioma spheres show high viability under hyperthermia, especially under high hyperthermic temperatures (42 °C). Further study revealed that the main mechanism lies in the high energy level of cells in 3D glioma spheres under hyperthermia, which enables the cells to respond promptly to thermal stimulation and maintain cellular viability by upregulating the chaperon protein Hsp70 and the anti-apoptotic pathway AKT. Besides, we also demonstrated that 3D glioma spheres show strong drug resistance to the thermo-chemical combination therapy. This study provides a new perspective on understanding the thermal response of combination therapy for tumor treatment.

Diagnostic and Therapeutic Approaches for Glioblastoma and Neuroblastoma Cancers Using Chlorotoxin Nanoparticles

Glioblastoma multiforme (GB) and high-risk neuroblastoma (NB) are known to have poor therapeutic outcomes. As for most cancers, chemotherapy and radiotherapy are the current mainstay treatments for GB and NB. However, the known limitations of systemic toxicity, drug resistance, poor targeted delivery, and inability to access the blood-brain barrier (BBB), make these treatments less satisfactory. Other treatment options have been investigated in many studies in the literature, especially nutraceutical and naturopathic products, most of which have also been reported to be poorly effective against these cancer types. This necessitates the development of treatment strategies with the potential to cross the BBB and specifically target cancer cells. Compounds that target the endopeptidase, matrix metalloproteinase 2 (MMP-2), have been reported to offer therapeutic insights for GB and NB since MMP-2 is known to be over-expressed in these cancers and plays significant roles in such physiological processes as angiogenesis, metastasis, and cellular invasion. Chlorotoxin (CTX) is a promising 36-amino acid peptide isolated from the venom of the deathstalker scorpion, Leiurus quinquestriatus, demonstrating high selectivity and binding affinity to a broad-spectrum of cancers, especially GB and NB through specific molecular targets, including MMP-2. The favorable characteristics of nanoparticles (NPs) such as their small sizes, large surface area for active targeting, BBB permeability, etc. make CTX-functionalized NPs (CTX-NPs) promising diagnostic and therapeutic applications for addressing the many challenges associated with these cancers. CTX-NPs may function by improving diffusion through the BBB, enabling increased localization of chemotherapeutic and genotherapeutic drugs to diseased cells specifically, enhancing imaging modalities such as magnetic resonance imaging (MRI), single-photon emission computed tomography (SPECT), optical imaging techniques, image-guided surgery, as well as improving the sensitization of radio-resistant cells to radiotherapy treatment. This review discusses the characteristics of GB and NB cancers, related treatment challenges as well as the potential of CTX and its functionalized NP formulations as targeting systems for diagnostic, therapeutic, and theranostic purposes. It also provides insights into the potential mechanisms through which CTX crosses the BBB to bind cancer cells and provides suggestions for the development and application of novel CTX-based formulations for the diagnosis and treatment of GB and NB in the future.

Highlighted Advances in Therapies for Difficult-To-Treat Brain Tumours Such as Glioblastoma

Glioblastoma multiforme (GBM) remains a challenging disease, as it is the most common and deadly brain tumour in adults and has no curative solution and an overall short survival time. This incurability and short survival time means that, despite its rarity (average incidence of 3.2 per 100,000 persons), there has been an increased effort to try to treat this disease. Standard of care in newly diagnosed glioblastoma is maximal tumour resection followed by initial concomitant radiotherapy and temozolomide (TMZ) and then further chemotherapy with TMZ. Imaging techniques are key not only to diagnose the extent of the affected tissue but also for surgery planning and even for intraoperative use. Eligible patients may combine TMZ with tumour treating fields (TTF) therapy, which delivers low-intensity and intermediate-frequency electric fields to arrest tumour growth. Nonetheless, the blood–brain barrier (BBB) and systemic side effects are obstacles to successful chemotherapy in GBM; thus, more targeted, custom therapies such as immunotherapy and nanotechnological drug delivery systems have been undergoing research with varying degrees of success. This review proposes an overview of the pathophysiology, possible treatments, and the most (not all) representative examples of the latest advancements.

Access to the CNS: Strategies to overcome the BBB

The blood-brain barrier (BBB) limits the access of substances to the central nervous system (CNS) which hinders the treatment of pathologies affecting the brain and the spinal cord. Nowadays, research is focus on new strategies to overcome the BBB and can treat the pathologies affecting the CNS are needed. In this review, the different strategies that allow and increase the access of substances to the CNS are analysed and extended commented, not only invasive strategies but also non-invasive ones. The invasive techniques include the direct injection into the brain parenchyma or the CSF and the therapeutic opening of the BBB, while the non-invasive techniques include the use of alternative routes of administration (nose-to-brain route), the inhibition of efflux transporters (as it is important to prevent the drug efflux from the brain and enhance the therapeutic efficiency), the chemical modification of the molecules (prodrugs and chemical drug delivery systems (CDDS)) and the use of nanocarriers. In the future, knowledge about nanocarriers to treat CNS diseases will continue to increase, but the use of other strategies such as drug repurposing or drug reprofiling, which are cheaper and less time consuming, may limit its transfer to society. The main conclusion is that the combination of different strategies may be the most interesting approach to increase the access of substances to the CNS.

In Vivo and In Vitro Biocompatibility Study of CuS Nanoparticles: Photosensitizer for Glioblastoma Photothermal Therapy

Although photothermal treatment (PTT) has made significant progress in the fight against cancer, certain types of malignant tumors are still difficult to eradicate. PTT uses photothermal transforming agents to absorb NIR light and convert it to thermal energy, causing cancer cell death. In this study, we synthesized alginate (Alg)-coated CuS nanoparticles (CuS@Alg) as photothermal transforming agents to kill glioblastoma cancer cells. Nanoparticles were synthesized via a facile method, then, were characterized with different techniques such as ultraviolet-visible spectroscopy (UV-Vis), Fourier transform infrared (FTIR), X-ray diffraction analysis (XRD), transmission electron microscopy (TEM), and dynamic light scattering (DLS). Nanoparticles show high stability, and are monodisperse. CuS@Alg was discovered to have a spherical shape, a hydrodynamic size of about 19.93 nm, and a zeta potential of - 9.74 mV. CuS@Alg is able to increase temperature of medium under NIR light. Importantly, in vitro investigations show that PTT based on CuS@Alg has a strong theraputic impact, resulting in much high effectiveness. The LD50 and histopathology assays were used to confirm the NPs' non-toxicity in vivo. Results from an in vivo subacute toxicity investigation showed that the fabricated NPs were perfectly safe to biomedical usage.

The role of cell membrane-coated nanoparticles as a novel treatment approach in glioblastoma

Glioblastoma multiform (GBM) is the most prevalent and deadliest primary brain malignancy in adults, whose median survival rate does not exceed 15 months after diagnosis. The conventional treatment of GBM, including maximal safe surgery followed by chemotherapy and radiotherapy, usually cannot lead to notable improvements in the disease prognosis and the tumor always recurs. Many GBM characteristics make its treatment challenging. The most important ones are the impermeability of the blood-brain barrier (BBB), preventing chemotherapeutic drugs from reaching in adequate amounts to the tumor site, intratumoral heterogeneity, and roles of glioblastoma stem cells (GSCs). To overcome these barriers, the recently-developed drug-carrying approach using nanoparticles (NPs) may play a significant role. NPs are tiny particles, usually less than 100 nm showing various diagnostic and therapeutic medical applications. In this regard, cell membrane (CM)-coated NPs demonstrated several promising effects in GBM in pre-clinical studies. They benefit from fewer adverse effects due to their specific targeting of tumor cells, biocompatibility because of their CM surfaces, prolonged half-life, easy penetrating of the BBB, and escaping from the immune reaction, making them an attractive option for GBM treatment. To date, CM-coated NPs have been applied to enhance the effectiveness of major therapeutic approaches in GBM treatment, including chemotherapy, immunotherapy, gene therapy, and photo-based therapies. Despite the promising results in pre-clinical studies regarding the effectiveness of CM-coated NPs in GBM, significant barriers like high expenses, complex preparation processes, and unknown long-term effects still hinder its mass production for the clinic. In this regard, the current study aims to provide an overview of different characteristics of CM-coated NPs and comprehensively investigate their application as a novel treatment approach in GBM.

Optomagnetic nanofluids for controlled brain hyperthermia: a critical study

Optomagnetic nanofluids (OMNFs) are colloidal dispersions of nanoparticles (NPs) with combined magnetic and optical properties. They are especially appealing in biomedicine since they can be used as minimally invasive platforms for controlled hyperthermia treatment of otherwise difficultly accessible tumors such as intracranial ones. On the one hand, magnetic NPs act as heating mediators when subjected to alternating magnetic fields or light irradiation. On the other hand, suitably tailored luminescent NPs can provide a precise and remote thermal readout in real time. The combination of heating and thermometric properties allows, in principle, to precisely monitor the increase in the temperature of brain tumors up to the therapeutic level, without causing undesired collateral damage. In this work we demonstrate that this view is an oversimplification since it ignores the presence of relevant interactions between magnetic (γ-Fe₂O₃ nanoflowers) and luminescent nanoparticles (Ag₂S NPs) that result in a detrimental alteration of their physicochemical properties. The magnitude of such interactions depends on the interparticle distance and on the surface properties of nanoparticles. Experiments performed in mouse brains (phantoms and ex vivo) revealed that OMNFs cannot induce relevant heating under alternating magnetic fields and fail to provide reliable temperature reading. In contrast, we demonstrate that the use of luminescent nanofluids (containing only Ag₂S NPs acting as both photothermal agents and nanothermometers) stands out as a better alternative for thermally monitored hyperthermia treatment of brain tumors in small animal models.

Remotely controlled near-infrared-triggered photothermal treatment of brain tumours in freely behaving mice using gold nanostars

Current clinical brain tumour therapy practices are based on tumour resection and post-operative chemotherapy or X-ray radiation. Resection requires technically challenging open-skull surgeries that can lead to major neurological deficits and, in some cases, death. Treatments with X-ray and chemotherapy, on the other hand, cause major side-effects such as damage to surrounding normal brain tissues and other organs. Here we report the development of an integrated nanomedicine-bioelectronics brain-machine interface that enables continuous and on-demand treatment of brain tumours, without open-skull surgery and toxicological side-effects on other organs. Near-infrared surface plasmon characteristics of our gold nanostars enabled the precise treatment of deep brain tumours in freely behaving mice. Moreover, the nanostars' surface coating enabled their selective diffusion in tumour tissues after intratumoral administration, leading to the exclusive heating of tumours for treatment. This versatile remotely controlled and wireless method allows the adjustment of nanoparticles' photothermal strength, as well as power and wavelength of the therapeutic light, to target tumours in different anatomical locations within the brain.

Nanotechnology-Based Combinatorial Anti-Glioblastoma Therapies: Moving from Terminal to Treatable

Aggressive glioblastoma (GBM) has no known treatment as a primary brain tumor. Since the cancer is so heterogeneous, an immunosuppressive tumor microenvironment (TME) exists, and the blood–brain barrier (BBB) prevents chemotherapeutic chemicals from reaching the central nervous system (CNS), therapeutic success for GBM has been restricted. Drug delivery based on nanocarriers and nanotechnology has the potential to be a handy tool in the continuing effort to combat the challenges of treating GBM. There are various new therapies being tested to extend survival time. Maximizing therapeutic effectiveness necessitates using many treatment modalities at once. In the fight against GBM, combination treatments outperform individual ones. Combination therapies may be enhanced by using nanotechnology-based delivery techniques. Nano-chemotherapy, nano-chemotherapy–radiation, nano-chemotherapy–phototherapy, and nano-chemotherapy–immunotherapy for GBM are the focus of the current review to shed light on the current status of innovative designs.

Anti-Fn14-Conjugated Prussian Blue Nanoparticles as a Targeted Photothermal Therapy Agent for Glioblastoma

Prussian blue nanoparticles (PBNPs) are effective photothermal therapy (PTT) agents: they absorb near-infrared radiation and reemit it as heat via phonon-phonon relaxations that, in the presence of tumors, can induce thermal and immunogenic cell death. However, in the context of central nervous system (CNS) tumors, the off-target effects of PTT have the potential to result in injury to healthy CNS tissue. Motivated by this need for targeted PTT agents for CNS tumors, we present a PBNP formulation that targets fibroblast growth factor-inducible 14 (Fn14)-expressing glioblastoma cell lines. We conjugated an antibody targeting Fn14, a receptor abundantly expressed on many glioblastomas but near absent on healthy CNS tissue, to PBNPs (aFn14-PBNPs). We measured the attachment efficiency of aFn14 onto PBNPs, the size and stability of aFn14-PBNPs, and the ability of aFn14-PBNPs to induce thermal and immunogenic cell death and target and treat glioblastoma tumor cells in vitro. aFn14 remained stably conjugated to the PBNPs for at least 21 days. Further, PTT with aFn14-PBNPs induced thermal and immunogenic cell death in glioblastoma tumor cells. However, in a targeted treatment assay, PTT was only effective in killing glioblastoma tumor cells when using aFn14-PBNPs, not when using PBNPs alone. Our methodology is novel in its targeting moiety, tumor application, and combination with PTT. To the best of our knowledge, PBNPs have not been investigated as a targeted PTT agent in glioblastoma via conjugation to aFn14. Our results demonstrate a novel and effective method for delivering targeted PTT to aFn14-expressing tumor cells via aFn14 conjugation to PBNPs.

Obstacles to Glioblastoma Treatment Two Decades after Temozolomide

Simple Summary

Glioblastomas are the most common and aggressive brain tumors in adults, with a median survival of 15 months. Treatment is surgical removal, followed by chemotherapy and/or radiotherapy. Current chemotherapeutics do not kill all the tumor cells and some cells survive, leading to the appearance of a new tumor resistant to the treatment. These treatment-resistant cells are called tumor stem cells. In addition, glioblastoma cells have a high capacity for migration, forming new tumors in areas distant from the original tumor. Studies are now focused on understanding the molecular mechanisms of chemoresistance and controlling drug entry into the brain to improve drug performance. Another promising therapeutic approach is the use of viruses that specifically destroy glioblastoma cells, preserving the neural tissue around the tumor. In this review, we summarize the main biological features of glioblastoma and the therapeutic targets that are currently under study for new clinical trials.

Abstract

Glioblastomas are considered the most common and aggressive primary brain tumor in adults, with an average of 15 months’ survival rate. The treatment is surgery resection, followed by chemotherapy with temozolomide, and/or radiotherapy. Glioblastoma must have wild-type IDH gene and some characteristics, such as TERT promoter mutation, EGFR gene amplification, microvascular proliferation, among others. Glioblastomas have great heterogeneity at cellular and molecular levels, presenting distinct phenotypes and diversified molecular signatures in each tumor mass, making it difficult to define a specific therapeutic target. It is believed that the main responsibility for the emerge of these distinct patterns lies in subcellular populations of tumor stem cells, capable of tumor initiation and asymmetric division. Studies are now focused on understanding molecular mechanisms of chemoresistance, the tumor microenvironment, due to hypoxic and necrotic areas, cytoskeleton and extracellular matrix remodeling, and in controlling blood brain barrier permeabilization to improve drug delivery. Another promising therapeutic approach is the use of oncolytic viruses that are able to destroy specifically glioblastoma cells, preserving the neural tissue around the tumor. In this review, we summarize the main biological characteristics of glioblastoma and the cutting-edge therapeutic targets that are currently under study for promising new clinical trials.

Glucose-Restricted Diet Regulates the Tumor Immune Microenvironment and Prevents Tumor Growth in Lung Adenocarcinoma

Background

Lung cancer is the second common cancer type in western countries and has a high mortality. During the development and progression of the tumor, the nutrients in its environment play a central role. The tumor cells depend crucially on glucose metabolism and uptake. Tumor cell metabolism is dominated by the Warburg effect, where tumor cells produce large amounts of lactate from pyruvate under aerobic conditions. We thus reasoned that, reducing carbohydrates in the diet might support anti-tumoral effects of current immunotherapy and additionally target tumor immune escape.

Objectives

The link between reducing carbohydrates to improve current immunotherapy is not clear. We thus aimed at analyzing the effects of different glucose levels on the tumor development, progression and the anti-tumoral immune response.

Methods

We correlated the clinical parameters of our LUAD cohort with different metabolic markers. Additionally, we performed cell culture experiments with A549 tumor cell line under different glucose levels. Lastly, we investigated the effect of low and high carbohydrate diet in an experimental murine model of lung cancer on the tumor progression and different immune subsets.

Results

Here we found a positive correlation between the body mass index (BMI), blood glucose levels, reduced overall survival (OS) and the expression of Insulin-like growth factor-1 receptor (IGF1R) in the lung tumoral region of patients with lung adenocarcinoma (LUAD). Furthermore, increasing extracellular glucose induced IGF1R expression in A549 LUAD cells. Functional studies in a murine model of LUAD demonstrated that, glucose restricted diet resulted in decreased tumor load in vivo. This finding was associated with increased presence of lung infiltrating cytotoxic CD8+ T effector memory (TEM), tissue resident memory T (TRM) and natural killer cells as well as reduced IGFR mRNA expression, suggesting that glucose restriction regulates lung immunity in the tumor microenvironment.

Conclusions

These results indicate that, glucose restricted diet improves lung immune responses of the host and suppresses tumor growth in experimental lung adenocarcinoma. As glucose levels in LUAD patients were negatively correlated to postoperative survival rates, glucose-restricted diet emerges as therapeutic avenue for patients with LUAD.

Multiphysical numerical study of photothermal therapy of glioblastoma with photoacoustic temperature monitoring in a mouse head

This paper presents a multiphysical numerical study of a photothermal therapy performed on a numerical phantom of a mouse head containing a glioblastoma. The study has been designed to be as realistic as possible. Heat diffusion simulations were performed on the phantom to understand the temperature evolution in the mouse head and therefore in the glioblastoma. The thermal dose has been calculated and lesions caused by heat are shown. The thermal damage on the tumor has also been quantified. To improve the effectiveness of the therapy, the photoabsorber's concentration was increased locally, at the tumor site, to mimic the effect of using absorbing contrast agents such as nanoparticles. Photoacoustic simulations were performed in order to monitor temperature in the phantom: as the Grüneisen parameter changes with the temperature, the photoacoustic signal undergoes changes that can be linked to temperature evolution. These photoacoustic simulations were performed at different instants during the therapy and the evolution of the photoacoustic signal as a function of the spatio-temporal distribution of the temperature in the phantom was observed and quantified. We have developed in this paper a numerical tool that can be used to help defining key parameters of a photothermal therapy.

Well-Defined Polyethylene Glycol Microscale Hydrogel Blocks Containing Gold Nanorods for Dual Photothermal and Chemotherapeutic Therapy

Local drug delivery offers a means of achieving a high concentration of therapeutic agents directly at the tumor site, whilst minimizing systemic toxicity. For heterogenous cancers such as glioblastoma, multimodal therapeutic approaches hold promise for better efficacy. Herein, we aimed to create a well-defined and reproducible drug delivery system that also incorporates gold nanorods for photothermal therapy. Solvent-assisted micromolding was used to create uniform sacrificial templates in which microscale hydrogels were formed with and without gold nanorods throughout their structure. The microscale hydrogels could be loaded with doxorubicin, releasing it over a period of one week, causing toxicity to glioma cells. Since these microscale hydrogels were designed for direct intratumoral injection, therefore bypassing the blood-brain barrier, the highly potent breast cancer therapeutic doxorubicin was repurposed for use in this study. By contrast, the unloaded hydrogels were well tolerated, without decreasing cell viability. Irradiation with near-infrared light caused heating of the hydrogels, showing that if concentrated at an injection site, these hydrogels maybe able to cause anticancer activity through two separate mechanisms.

Applications of the ROS-Responsive Thioketal Linker for the Production of Smart Nanomedicines

Reactive oxygen species (ROS)-sensitive drug delivery systems (DDS) specifically responding to altered levels of ROS in the pathological microenvironment have emerged as an effective means to enhance the pharmaceutical efficacy of conventional nanomedicines, while simultaneously reducing side effects. In particular, the use of the biocompatible, biodegradable, and non-toxic ROS-responsive thioketal (TK) functional group in the design of smart DDS has grown exponentially in recent years. In the design of TK-based DDS, different technological uses of TK have been proposed to overcome the major limitations of conventional DDS counterparts including uncontrolled drug release and off-target effects. This review will focus on the different technological uses of TK-based biomaterials in smart nanomedicines by using it as a linker to connect a drug on the surface of nanoparticles, form prodrugs, as a core component of the DDS to directly control its structure, to control the opening of drug-releasing gates or to change the conformation of the nano-systems. A comprehensive view of the various uses of TK may allow researchers to exploit this reactive linker more consciously while designing nanomedicines to be more effective with improved disease-targeting ability, providing novel therapeutic opportunities in the treatment of many diseases.

The Advances in Glioblastoma On-a-Chip for Therapy Approaches

Simple Summary

This systematic review showed different therapeutic approaches to glioblastoma on-a-chip with varying levels of complexity, answering, from the simplest question to the most sophisticated questions, in a biological system integrated in an efficient way. With advances in manufacturing protocols, soft lithography in PDMS material was the most used in the studies, applying different strategy geometrics in device construction. The microenvironment showed the relevant elaborations in co-culture between mainly human tumor cells and support cells involved in the collagen type I matrix; remaining an adequate way to assess the therapeutic approach. The most complex devices showed efficient intersection between different systems, allowing in vitro studies with major human genetic similarity, reproducibility, and low cost, on a highly customizable platform.

Abstract

This systematic review aimed to verify the use of microfluidic devices in the process of implementing and evaluating the effectiveness of therapeutic approaches in glioblastoma on-a-chip, providing a broad view of advances to date in the use of this technology and their perspectives. We searched studies with the variations of the keywords “Glioblastoma”, “microfluidic devices”, “organ-on-a-chip” and “therapy” of the last ten years in PubMed and Scopus databases. Of 446 articles identified, only 22 articles were selected for analysis according to the inclusion and exclusion criteria. The microfluidic devices were mainly produced by soft lithography technology, using the PDMS material (72%). In the microenvironment, the main extracellular matrix used was collagen type I. Most studies used U87-MG glioblastoma cells from humans and 31.8% were co-cultivated with HUVEC, hCMEC/D3, and astrocytes. Chemotherapy was the majority of therapeutic approaches, assessing mainly the cellular viability and proliferation. Furthermore, some alternative therapies were reported in a few studies (22.6%). This study identified a diversity of glioblastoma on-a-chip to assess therapeutic approaches, often using intermediate levels of complexity. The most advanced level implemented the intersection between different biological systems (liver–brain or intestine–liver–brain), BBB model, allowing in vitro studies with greater human genetic similarity, reproducibility, and low cost, in a highly customizable platform.

A novel therapeutic strategy of multimodal nanoconjugates for state-of-the-art brain tumor phototherapy

Background

The outcome of phototherapy, including photothermal therapy (PTT) and photodynamic therapy (PDT) for glioblastoma multiforme (GBM), is disappointing due to insufficient photoconversion efficiency and low targeting rate. The development of phototherapeutic agents that target GBM and generate high heat and potent ROS is important to overcome the weak anti-tumor effect.

Results

In this study, nanoconjugates composed of gold nanoparticles (AuNPs) and photosensitizers (PSs) were prepared by disulfide conjugation between Chlorin e6 (Ce6) and glutathione coated-AuNP. The maximum heat dissipation of the nanoconjugate was 64.5 ± 4.5 °C. Moreover, the proximate conjugation of Ce6 on the AuNP surface resulted in plasmonic crossover between Ce6 and AuNP. This improves the intrinsic ROS generating capability of Ce6 by 1.6-fold compared to that of unmodified-Ce6. This process is called generation of metal-enhanced reactive oxygen species (MERos). PEGylated-lactoferrin (Lf-PEG) was incorporated onto the AuNP surface for both oral absorption and GBM targeting of the nanoconjugate (denoted as Ce6-AuNP-Lf). In this study, we explored the mechanism by which Ce6-AuNP-Lf interacts with LfR at the intestinal and blood brain barrier (BBB) and penetrates these barriers with high efficiency. In the orthotopic GBM mice model, the oral bioavailability and GBM targeting amount of Ce6-AuNP-Lf significantly improved to 7.3 ± 1.2% and 11.8 ± 2.1 μg/kg, respectively. The order of laser irradiation, such as applying PDT first and then PTT, was significant for the treatment outcome due to the plasmonic advantages provided by AuNPs to enhance ROS generation capability. As a result, GBM-phototherapy after oral administration of Ce6-AuNP-Lf exhibited an outstanding anti-tumor effect due to GBM targeting and enhanced photoconversion efficiency.

Conclusions

The designed nanoconjugates greatly improved ROS generation by plasmonic crossover between AuNPs and Ce6, enabling sufficient PDT for GBM as well as PTT. In addition, efficient GBM targeting through oral administration was possible by conjugating Lf to the nanoconjugate. These results suggest that Ce6-AuNP-Lf is a potent GBM phototherapeutic nanoconjugate that can be orally administered.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s12951-021-01220-9.

Deep Penetration of Nanolevel Drugs and Micrometer-Level T Cells Promoted by Nanomotors for Cancer Immunochemotherapy

The ability of nanomotors to promote the deep penetration of themselves and the loaded drugs in diseased tissues has been proposed and confirmed. However, whether such motion behavior of the nanomotors can also promote deep penetration of micrometer-sized immune cells in the diseased microenvironment, which is important for the immunotherapy of some diseases, has not been mentioned. Herein, we construct a nitric oxide (NO)-driven nanomotor that can move in the tumor microenvironment, focusing on its motion behavior and the role of NO, the beneficial product released during movement from this kind of nanomotor, in regulating the infiltration behavior and activity of immune cells. It can be found that the drug-loaded nanomotors with both NO-releasing ability and motility can promote the normalization of the tumor vasculature system and the degradation of the intrinsic extracellular matrix (ECM), which can significantly improve the tumor infiltration ability of T cells in vivo. The efficiency of T-cell infiltration in tumor tissue in vivo increased from 2.1 to 28.2%. Both subcutaneous and intraperitoneal implantation tumor models can validate the excellent antitumor effect of drug-loaded NO-driven nanomotors. This combination of motility of the power source from nanomotors and their physiological function offers a design idea for therapeutic agents for the future immunotherapy of many diseases.

Development of a multi-functional preclinical device for the treatment of glioblastoma

Glioblastoma multiforme (GBM) is one of the most common and aggressive malignant primary brain tumors in adults. The treatment of GBM is limited by the blood-brain barrier (BBB), which limits the diffusion of appropriate concentrations of therapeutic agents at the tumor site. Among experimental therapies, photo-thermal therapy (PTT) mediated by nanoparticles is a promising strategy. To propose a preclinical versatile research instrument for the development of new PTT for GBM, a multipurpose integrated preclinical device was developed. The setup is able to perform: i) BBB permeabilization by focused ultrasound sonication (FUS); ii) PTT with continuous wave laser; iii) in situ temperature monitoring with photo-acoustic (PA) measurements. In vivo preliminary subcutaneous and transcranial experiments were conducted on healthy or tumor-bearing mice. Transcranial FUS-induced BBB permeabilization was validated using single photon emission computed tomography (SPECT) imaging. PTT capacities were monitored by PA thermometry, and are illustrated through subcutaneous and transcranial in vivo experiments. The results show the therapeutic possibilities and ergonomy of such integrated device as a tool for the validation of future treatments.