Evaluation of lauroyl-gemcitabine-loaded hydrogel efficacy in glioblastoma rat models

The Potential of the Fibronectin Inhibitor Arg-Gly-Asp-Ser in the Development of Therapies for Glioblastoma

Glioblastoma (GBM) is the most lethal and common malignant primary brain tumor in adults. An important feature that supports GBM aggressiveness is the unique composition of its extracellular matrix (ECM). Particularly, fibronectin plays an important role in cancer cell adhesion, differentiation, proliferation, and chemoresistance. Thus, herein, a hydrogel with mechanical properties compatible with the brain and the ability to disrupt the dynamic and reciprocal interaction between fibronectin and tumor cells was produced. High-molecular-weight hyaluronic acid (HMW-HA) functionalized with the inhibitory fibronectin peptide Arg-Gly-Asp-Ser (RGDS) was used to produce the polymeric matrix. Liposomes encapsulating doxorubicin (DOX) were also included in the hydrogel to kill GBM cells. The resulting hydrogel containing liposomes with therapeutic DOX concentrations presented rheological properties like a healthy brain. In vitro assays demonstrated that unmodified HMW-HA hydrogels only caused GBM cell killing after DOX incorporation. Conversely, RGDS-functionalized hydrogels displayed per se cytotoxicity. As GBM cells produce several proteolytic enzymes capable of disrupting the peptide-HA bond, we selected MMP-2 to illustrate this phenomenon. Therefore, RGDS internalization can induce GBM cell apoptosis. Importantly, RGDS-functionalized hydrogel incorporating DOX efficiently damaged GBM cells without affecting astrocyte viability, proving its safety. Overall, the results demonstrate the potential of the RGDS-functionalized hydrogel to develop safe and effective GBM treatments.

Local delivery of doxorubicin prodrug via lipid nanocapsule-based hydrogel for the treatment of glioblastoma

Glioblastoma (GBM) recurrences appear in most cases around the resection cavity borders and arise from residual GBM cells that cannot be removed by surgery. Here, we propose a novel treatment that combines the advantages of nanomedicine and local drug delivery to target these infiltrating GBM cells. We developed an injectable lipid nanocapsule (LNC)-based formulation loaded with lauroyl-doxorubicin prodrug (DOXC12). Firstly, we demonstrated the efficacy of intratumoral administration of DOXC12 in GL261 GBM-bearing mice, which extended mouse survival. Then, we formulated an injectable hydrogel by mixing the appropriate amount of prodrug with the lipophilic components of LNC. We optimized the hydrogel by incorporating cytidine-C16 (CytC16) to achieve a mechanical stiffness adapted for an application in the brain post-surgery (DOXC12-LNCCL). DOXC12-LNCCL exhibited high DOXC12 encapsulation efficiency (95%) and a size of approximately 60 nm with sustained drug release for over 1 month in vitro. DOXC12-LNCCL exhibited enhanced cytotoxicity compared to free DOXC12 (IC50 of 349 and 86 nM, respectively) on GL261 GBM cells and prevented the growth of GL261 spheroids cultured on organotypic brain slices. In vivo, post-surgical treatment with DOXC12-LNCCL significantly improved the survival of GL261-bearing mice. The combination of this local treatment with the systemic administration of anti-inflammatory drug ibuprofen further delayed the onset of recurrences. In conclusion, our study presents a promising therapeutic approach for the treatment of GBM. By targeting residual GBM cells and reducing the inflammation post-surgery, we present a new strategy to delay the onset of recurrences in the gap period between surgery and standard of care therapy.

Glioblastoma-targeted, local and sustained drug delivery system based on an unconventional lipid nanocapsule hydrogel

The objective of this work was to develop an implantable therapeutic hydrogel that will ensure continuity in treatment between surgery and radiochemotherapy for patients with glioblastoma (GBM). A hydrogel of self-associated gemcitabine-loaded lipid nanocapsules (LNC) has shown therapeutic efficacy in vivo in murine GBM resection models. To improve the targeting of GBM cells, the NFL-TBS.40-63 peptide (NFL), was associated with LNC. The LNC-based hydrogels were formulated with the NFL. The peptide was totally and instantaneously adsorbed at the LNC surface, without modifying the hydrogel mechanical properties, and remained adsorbed to the LNC surface after the hydrogel dissolution. In vitro studies on GBM cell lines showed a faster internalization of the LNC and enhanced cytotoxicity, in the presence of NFL. Finally, in vivo studies in the murine GBM resection model proved that the gemcitabine-loaded LNC with adsorbed NFL could target the non-resected GBM cells and significantly delay or even inhibit the apparition of recurrences.

Establishment of a Rodent Glioblastoma Partial Resection Model for Chemotherapy by Local Drug Carriers-Sharing Experience

Local drug delivery systems (LDDS) represent a promising therapy strategy concerning the most common and malignant primary brain tumor glioblastoma (GBM). Nevertheless, to date, only a few systems have been clinically applied, and their success is very limited. Still, numerous new LDDS approaches are currently being developed. Here, (partial resection) GBM animal models play a key role, as such models are needed to evaluate the therapy prior to any human application. However, such models are complex to establish, and only a few reports detail the process. Here, we report our results of establishing a partial resection glioma model in rats suitable for evaluating LDDS. C6-bearing Wistar rats and U87MG-spheroids- and patient-derived glioma stem-like cells-bearing athymic rats underwent tumor resection followed by the implantation of an exemplary LDDS. Inoculation, tumor growth, residual tumor tissue, and GBM recurrence were reliably imaged using high-resolution Magnetic Resonance Imaging. The release from an exemplary LDDS was verified in vitro and in vivo using Fluorescence Molecular Tomography. The presented GBM partial resection model appears to be well suited to determine the efficiency of LDDS. By sharing our expertise, we intend to provide a powerful tool for the future testing of these very promising systems, paving their way into clinical application.

Physicochemical Characterization of Ferrocifen Lipid Nanocapsules: Customized Drug Delivery Systems Guided by the Molecular Structure

Ferrocifens, lipophilic organometallic complexes, comprise a biologically active redox motif [ferrocenyl-ene-p-phenol] which confers very interesting cytotoxic properties to this family. However, because of their highly lipophilic nature, a formulation stage is required before being administered in vivo. In recent decades, ferrocifen lipid nanocapsules (LNCs) have been successfully formulated and have demonstrated anticancer activity on multidrug-resistant cancers in several mice and rat models (glioblastoma, breast cancer, and metastatic melanoma). A recent family of ferrocifens (succinimidoalkyl-ferrociphenols, including P722) appears to be most efficacious on several resistant cancer cell lines, with IC₅₀ values in the nanomolar range together with promising in vivo results on murine ovarian cancer models. As LNCs are composed of an oily core (caprylic/capric triglycerides), modulation of the succinimido-ferrociphenol lipophilicity could be a valuable approach toward improving the drug loading in LNCs. As the drug loading of the diphenol P722 in LNCs was low, it was structurally modified to increase its lipophilicity and thereby the payload in LNCs. Chemical modification led to a series of five succinimido-ferrocifens. Results confirmed that these slight structural modifications led to increased drug loading in LNCs for all ferrocifens, with no reduction of their cytotoxicity on the SKOV3 ovarian cancer cell line. Interestingly, encapsulation of two of the ferrocifens, diester P769 and monophenolic ester (E)-P998, led to the formation of a gel. This was unprecedented behavior, a phenomenon that could be rationalized in terms of the positioning of ferrocifens in LNCs as shown by the decrease of interfacial tension measurements at the water/oil interface. Moreover, these results highlighted the importance of obtaining a gel of this particular motif, in which the acetylated phenolic ring and the succinimidoalkyl moieties are mutually cis relative to the central double bond. Promising perspectives to use these ferrocifen-loaded LNCs to treat glioblastoma could be readily envisaged by local application of the gel in the cavity after tumor resection.

Glioblastoma: Current Status, Emerging Targets, and Recent Advances

Glioblastoma (GBM) is a highly malignant brain tumor characterized by a heterogeneous population of genetically unstable and highly infiltrative cells that are resistant to chemotherapy. Although substantial efforts have been invested in the field of anti-GBM drug discovery in the past decade, success has primarily been confined to the preclinical level, and clinical studies have often been hampered due to efficacy-, selectivity-, or physicochemical property-related issues. Thus, expansion of the list of molecular targets coupled with a pragmatic design of new small-molecule inhibitors with central nervous system (CNS)-penetrating ability is required to steer the wheels of anti-GBM drug discovery endeavors. This Perspective presents various aspects of drug discovery (challenges in GBM drug discovery and delivery, therapeutic targets, and agents under clinical investigation). The comprehensively covered sections include the recent medicinal chemistry campaigns embarked upon to validate the potential of numerous enzymes/proteins/receptors as therapeutic targets in GBM.

The use of radiosensitizing agents in the therapy of glioblastoma multiforme-a comprehensive review

BACKGROUND

Glioblastoma is the most common malignant brain tumor in human adults. Despite several improvements in resective as well as adjuvant therapy over the last decades, its overall prognosis remains poor. As a means of improving patient outcome, the possibility of enhancing radiation response by using radiosensitizing agents has been tested in an array of studies.

METHODS

A comprehensive review of clinical trials involving radiation therapy in combination with radiosensitizing agents on patients diagnosed with glioblastoma was performed in the National Center for Biotechnology Information's PubMed database.

RESULTS

A total of 96 papers addressing this matter were published between 1976 and 2021, of which 63 matched the subject of this paper. All papers were reviewed, and their findings discussed in the context of their underlining mechanisms of radiosensitization.

CONCLUSION

In the history of glioblastoma treatment, several approaches of optimizing radiation-effectiveness using radiosensitizers have been made. Even though several different strategies and agents have been explored, clear evidence of improved patient outcome is still missing. Tissue-selectiveness and penetration of the blood-brain barrier seem to be major roadblocks; nevertheless, modern strategies try to circumvent these obstacles, using novel sensitizers based on preclinical data or alternative ways of delivery.

Local Delivery and Glioblastoma: Why Not Combining Sustained Release and Targeting?

Glioblastoma is one of the most aggressive brain tumors and is associated with a very low overall median survival despite the current treatment. The standard of care used in clinic is the Stupp's protocol which consists of a maximal resection of the tumor when possible, followed by radio and chemotherapy using temozolomide. However, in most cases, glioblastoma cells infiltrate healthy tissues and lead to fatal recurrences. There are a lot of hurdles to overcome in the development of new therapeutic strategies such as tumor heterogeneity, cell infiltration, alkylating agent resistance, physiological barriers, etc., and few treatments are on the market today. One of them is particularly appealing because it is a local therapy, which does not bring additional invasiveness since tumor resection is included in the gold standard treatment. They are implants: the Gliadel^® wafers, which are deposited post-surgery. Nevertheless, in addition to presenting important undesirable effects, it does not bring any major benefit in the therapy despite the strategy being particularly attractive. The purpose of this review is to provide an overview of recent advances in the development of innovative therapeutic strategies for glioblastoma using an implant-type approach. The combination of this local strategy with effective targeting of the tumor microenvironment as a whole, also developed in this review, may be of interest to alleviate some of the obstacles encountered in the treatment of glioblastoma.

Rationally designed drug delivery systems for the local treatment of resected glioblastoma

Glioblastoma (GBM) is a particularly aggressive brain cancer associated with high recurrence and poor prognosis. The standard of care, surgical resection followed by concomitant radio- and chemotherapy, leads to low survival rates. The local delivery of active agents within the tumor resection cavity has emerged as an attractive means to initiate oncological treatment immediately post-surgery. This complementary approach bypasses the blood-brain barrier, increases the local concentration at the tumor site while reducing or avoiding systemic side effects. This review will provide a global overview on the local treatment for GBM with an emphasis on the lessons learned from past clinical trials. The main parameters to be considered to rationally design fit-of-purpose biomaterials and develop drug delivery systems for local administration in the GBM resection cavity to prevent the tumor recurrence will be described. The intracavitary local treatment of GBM should i) use materials that facilitate translation to the clinic; ii) be characterized by easy GMP effective scaling up and easy-handling application by the neurosurgeons; iii) be adaptable to fill the tumor-resected niche, mold to the resection cavity or adhere to the exposed brain parenchyma; iv) be biocompatible and possess mechanical properties compatible with the brain; v) deliver a therapeutic dose of rationally-designed or repurposed drug compound(s) into the GBM infiltrative margin. Proof of concept with high translational potential will be provided. Finally, future perspectives to facilitate the clinical translation of the local perisurgical treatment of GBM will be discussed.

EGFRvIII peptide nanocapsules and bevacizumab nanocapsules: a nose-to-brain multitarget approach against glioblastoma

Aim: To evaluate the antitumor efficacy of bevacizumab-functionalized nanocapsules in a rat glioblastoma model after the pretreatment with nanocapsules functionalized with a peptide-specific to the epidermal growth factor receptor variant III. Materials & methods: Nanocapsules were prepared, physicochemical characterized and intranasally administered to rats. Parameters such as tumor size, histopathological characteristics and infiltration of CD8⁺ T lymphocytes were evaluated. Results: The strategy of treatment resulted in a reduction of 87% in the tumor size compared with the control group and a higher infiltration of CD8⁺ T lymphocytes in tumoral tissue. Conclusion: The block of two different molecular targets using nose-to-brain delivery represents a new and promising approach against glioblastoma.

Does local drug delivery still hold therapeutic promise for brain cancer? A systematic review

BACKGROUND

Glioblastoma (GBM) is the most common and aggressive primary brain tumor in adults. Despite the gold standard treatment combining surgical resection, radiation and adjuvant plus concomitant chemotherapy with the alkylating agent temozolomide (TMZ), the prognosis remains poor (5-year survival rate < 10%). Over the last three decades, a vast array of drug delivery systems (DDS) have been developed for the local treatment of GBM, with the majority of the characterization being undertaken in pre-clinical models. We aimed to gain an overview of the potential efficacy of such local delivery systems in comparison to the systemic drug administration.

METHODS

In this paper, a systematic search of Pubmed, Web of Science, and Scopus was performed using pre-determined search terms. Studies were assessed for eligibility based on specific inclusion and exclusion criteria. A total of fifteen publications were included for analysis of local vs systemic group median survival, tumor volume and adverse events, with five brought forward for a meta-analysis.

RESULTS

The majority of studies showed local delivery to be more efficacious than systemic administration, regardless of the drug, animal model, type of DDS used, or duration of the study. The meta-analysis also showed that the mean difference between median survival ratios was statistically significantly in favor of local delivery.

CONCLUSION

Preclinical evidence shows that there is a firm rationale for further developing DDS for local therapeutic delivery to GBM and other brain cancers.

Galenic Lab-on-a-Chip concept for lipid nanocapsules production

The continuous production of drug delivery systems assisted by microfluidics has drawn a growing interest because of the high reproducibility, low batch-to-batch variations, narrow and controlled particle size distributions and scale-up ease induced by this kind of processes. Besides, microfluidics offers opportunities for high throughput screening of process parameters and the implementation of process characterization techniques as close to the product as possible. In this context, we propose to spotlight the GALECHIP concept through the development of an instrumented microfluidic pilot considered as a Galenic Lab-on-a-Chip to formulate nanomedicines, such as lipid nanocapsules (LNCs), under controlled process conditions. In this paper we suggest an optimal rational development in terms of chip costs and designs. First, by using two common additive manufacturing techniques, namely fused deposition modelling and multi-jet modelling to prototype customized 3D microfluidic devices (chips and connectors). Secondly, by manufacturing transparent Silicon (Si)/Glass chips with similar channel geometries but obtained by a new approach of deep reactive ion etching (DRIE) technology suitable with in situ small angle X-ray scattering characterizations. LNCs were successfully produced by a phase inversion composition (PIC) process with highly monodispersed sizes from 25 nm to 100 nm and formulated using chips manufactured by 3D printing and DRIE technologies. The transparent Si/Glass chip was also used for the small angle X-ray scattering (SAXS) analysis of the LNC formulation with the PIC process. The 3D printing and DRIE technologies and their respective advantages are discussed in terms of cost, easiness to deploy and process developments in a GALECHIP point of view.

Polymer-free hydrogel made of lipid nanocapsules, as a local drug delivery platform

Nanoparticle-loaded hydrogels are attractive pharmaceutical drug delivery systems that combine the advantages of both hydrogel (local administration and/or sustained drug release) and nanoparticle (stealthiness, targeting and decreased toxicity). The design of nanoparticle-loaded hydrogels is largely conventional, consisting of the dispersion of nanoparticles in a natural or synthetic polymer matrix to form a gel network. Novel nanoparticle-loaded hydrogels architecture could provide advantages in terms of innovation and application. We focused on the development of lipid nanocapsule (LNC)-based hydrogels without the use of a polymer matrix as a platform for drug delivery. Cytidine was modified by grafting palmitoyl chains (CytC16) and the new entity was added during the LNC phase-inversion formulation process allowing spontaneous gelation. Positioned at the oil/water interface, CytC16 acts as a crosslinking agent between LNCs. Association of the LNCs in a three-dimensional network led to the formation of polymer-free hydrogels. The viscoelastic properties of the LNC-based hydrogels depended on the LNC concentration and CytC16 loading but were not affected by the LNC size distribution. The LNC and drug-release profiles were controlled by the mechanical properties of the LNC-based hydrogels (slower release profiles correlated with higher viscoelasticity). Finally, the subcutaneous administration of LNC-based hydrogels led to classic inflammatory reactions of the foreign body-reaction type due to the endogenous character of CytC16, shown by cellular viability assays. New-generation nanoparticle-loaded hydrogels (LNC-based polymer-free hydrogels) show promise as implants for pharmaceutical applications. Once LNC release is completed, no gel matrix remains at the injection site, minimizing the additional toxicity due to the persistence of polymeric implants. Sustained drug-release profiles can be controlled by the mechanical properties of the hydrogels and could be tailor-made, depending on the therapeutic strategy chosen.

Bioscaffold-based study of glioblastoma cell behavior and drug delivery for tumor therapy

Glioblastoma multiforme (GBM) is a severe form of brain cancer with an average five-year survival rate of 6.7%. Current treatment strategies include surgical resection of the tumor area and lining the lesion site with therapeutics, which offer only a moderate impact on increasing survival rates. Drug-testing models based on the monolayer cell culture method may partially explain the lack of advancement in effective GBM treatment, because this model is limited in its ability to show heterogeneous cell-cell and cell-environment interactions as tumor cells in the in vivo state. The development of bioscaffold-based culture models is an important improvement in GBM research, preclinical trials, and targeted drug testing, through better mimicking of the heterogeneity of tumor environmental conditions. A major hurdle towards better GBM outcomes is in delivering medication across the blood-brain barrier (BBB), which normally prevents the crossing of materials into the treatment site. The delivery of therapeutics using bioscaffolds is a potential means of overcoming the BBB and could potentially facilitate long-lasting drug release. A number of natural and synthetic materials have been studied for their biodegradability, toxicity, distribution, and pharmaceutical stability, which are needed to determine the overall effectiveness and safety of glioblastoma treatment. This review summarizes advancements in the research of bioscaffold-based GBM cell growth systems and the potential of using bioscaffolds as a carrier for drug delivery.

Photosensitizer delivery by fibrin glue: potential for bypassing the blood-brain barrier

Fibrin glue (FG) has potential as a delivery vehicle for photosensitizer directly to the resection cavity, so it may bypass the blood-brain barrier (BBB) and increase the concentration of successfully delivered photosensitizer. A specialized form of photodynamic therapy (PDT), photochemical internalization (PCI), which involves both photosensitizer and chemotherapeutic agent internalization, can locally inhibit the growth of cells. This will allow the reduction of recurrence of malignant gliomas around surgical resection. This study will look at the efficacy of FG loaded with drugs in mediating both PDT and PCI in inhibiting 3-dimensional tumor spheroid growth in vitro. Experiments were conducted on spheroids comprised of F98 glioma cells using photosensitizer AlPcS_2a and chemotherapeutic drug bleomycin (BLM). At 2-, 24-, 48-, and 72-h increments, supernatant covering an FG layer within a well was collected and replaced by fresh medium, then added to spheroid-containing wells, which contained the respective chemicals for PDT and PCI. The wells were then exposed to light treatment from a diode laser, and after, spheroid growth was monitored for a period of 14 days. Significant spheroid growth inhibition was observed in both PDT and PCI modalities, but was far greater in PCI. Additionally, complete growth suppression was achieved via PCI at the highest radiant exposure. Achieving a slow photosensitizer release, significant F98 spheroid inhibition was observed in FG-mediated PDT and PCI. The present study showed BLM-PCI was the most efficacious of the two modalities.

Advances in drug delivery technology for the treatment of glioblastoma multiforme

Glioblastoma multiforme (GBM) is a particularly aggressive and malignant type of brain tumor, notorious for its high recurrence rate and low survival rate. The treatment of GBM is challenging mainly because several issues associated with the GBM microenvironment have not yet been resolved. These obstacles originate from a variety of factors such as genetics, anatomy, and cytology, all of which collectively hinder the treatment of GBM. Recent advances in materials and device engineering have presented new perspectives with regard to unconventional drug administration methods for GBM treatment. Such novel drug delivery approaches, based on the clear understanding of the intrinsic properties of GBM, have shown promise in overcoming some of the obstacles. In this review, we first recapitulate the first-line therapy and clinical challenges in the current treatment of GBM. Afterwards, we introduce the latest technological advances in drug delivery strategies to improve the efficiency for GBM treatment, mainly focusing on materials and devices. We describe such efforts by classifying them into two categories, systemic and local drug delivery. Finally, we discuss unmet challenges and prospects for the clinical translation of these drug delivery technologies.

Emerging technologies for local cancer treatment

The fundamental limitations of systemic therapeutic administration have prompted the development of local drug delivery platforms as a solution to increase effectiveness and reduce side effects. By confining therapeutics to the site of disease, local delivery technologies can enhance therapeutic index. This review highlights recent advances and opportunities in local drug delivery strategies for cancer treatment in addition to challenges that need to be addressed to facilitate clinical translation. The benefits of local cancer treatment combined with technological advancements and increased understanding of the tumor microenvironment, present a prime breakthrough opportunity for safer and more effective therapies.

Emerging insights on drug delivery by fatty acid mediated synthesis of lipophilic prodrugs as novel nanomedicines

Many drug molecules that are currently in the market suffer from short half-life, poor absorption, low specificity, rapid degradation, and resistance development. The design and development of lipophilic prodrugs can provide numerous benefits to overcome these challenges. Fatty acids (FAs), which are lipophilic biomolecules constituted of essential components of the living cells, carry out many necessary functions required for the development of efficient prodrugs. Chemical conjugation of FAs to drug molecules may change their pharmacodynamics/pharmacokinetics in vivo and even their toxicity profile. Well-designed FA-based prodrugs can also present other benefits, such as improved oral bioavailability, promoted tumor targeting efficiency, controlled drug release, and enhanced cellular penetration, leading to improved therapeutic efficacy. In this review, we discuss diverse drug molecules conjugated to various unsaturated FAs. Furthermore, various drug-FA conjugates loaded into various nanostructure delivery systems, including liposomes, solid lipid nanoparticles, emulsions, nano-assemblies, micelles, and polymeric nanoparticles, are reviewed. The present review aims to inspire readers to explore new avenues in prodrug design based on the various FAs with or without nanostructured delivery systems.

Hydrogels based on modified pectins capable of modulating neural cell behavior as prospective biomaterials in glioblastoma treatment

Glioblastoma is the most common malignant tumor of the brain, but its treatment outcomes can be improved by new therapeutic techniques using biocompatible materials. Utilizing controllable alkaline de-esterification we obtained pectin preparation with 27.4% esterification degree and used it for bio-artificial matrix production. We discovered optimal gelation conditions in the presence of Ca²⁺ by the analysis of visco-elastic properties of the gels and produced a series of biomaterials in hydrogel forms. Hydrogels based on low-esterified pectin significantly slow down the metabolism of C6 glioma cells and neural stem cells (NSCs) and slightly decrease the viability of the C6 glioma, but not of NSCs. This happens due to a decrease in cell proliferation rate, while apoptosis degrees remain stable or negligibly decrease. We created a set of pectin hydrogels supplemented with different ratios of two ECM proteins-collagens I and IV. We have shown that the formation of cell processes in glioma C6 can be regulated by varying the ratio of two ECM proteins in gels used for 3D cell cultivation. Thus, composite matrix materials obtained can be used for modeling brain tumor invasion. The results presented suggest that modified pectins supplemented with two collagen types may serve as prospective biomaterials for glioblastoma treatment due to their ability to regulate glioma cell dynamics.

Doxorubicin Loaded Poloxamer Thermosensitive Hydrogels: Chemical, Pharmacological and Biological Evaluation

(1) Background: doxorubicin is a potent chemotherapeutic agent, but it has limitations regarding its side effects and therapy resistance. Hydrogels potentially deal with these problems, but several characterizations need to be optimized to better understand how hydrogel assisted chemotherapy works. Poloxamer 407 (P407) hydrogels were mixed with doxorubicin and physico-chemical, biological, and pharmacological characterizations were considered. (2) Methods: hydrogels were prepared by mixing P407 in PBS at 4 °C. Doxorubicin was added upon solutions became clear. Time-to-gelation, hydrogel morphology, and micelles were studied first. The effects of P407-doxorubicin were evaluated on MC-38 colon cancer cells. Furthermore, doxorubicin release was assessed and contrasted with non-invasive in vivo whole body fluorescence imaging. (3) Results: 25% P407 had favorable gelation properties with pore sizes of 30–180 µm. P407 micelles were approximately 5 nm in size. Doxorubicin was fully released in vitro from 25% P407 hydrogel within 120 h. Furthermore, P407 micelles strongly enhanced the anti-neoplastic effects of doxorubicin on MC-38 cells. In vivo fluorescence imaging revealed that hydrogels retained fluorescence signals at the injection site for 168 h. (4) Conclusions: non-invasive imaging showed how P407 gels retained drug at the injection site. Doxorubicin P407 micelles strongly enhanced the anti-tumor effects.

Overcoming the Blood-Brain Barrier: Successes and Challenges in Developing Nanoparticle-Mediated Drug Delivery Systems for the Treatment of Brain Tumours

High-grade gliomas are still characterized by a poor prognosis, despite recent advances in surgical treatment. Chemotherapy is currently practiced after surgery, but its efficacy is limited by aspecific toxicity on healthy cells, tumour cell chemoresistance, poor selectivity, and especially by the blood–brain barrier (BBB). Thus, despite the large number of potential drug candidates, the choice of effective chemotherapeutics is still limited to few compounds. Malignant gliomas are characterized by high infiltration and neovascularization, and leaky BBB (the so-called blood–brain tumour barrier); surgical resection is often incomplete, leaving residual cells that are able to migrate and proliferate. Nanocarriers can favour delivery of chemotherapeutics to brain tumours owing to different strategies, including chemical stabilization of the drug in the bloodstream; passive targeting (because of the leaky vascularization at the tumour site); inhibition of drug efflux mechanisms in endothelial and cancer cells; and active targeting by exploiting carriers and receptors overexpressed at the blood–brain tumour barrier. Within this concern, a suitable nanomedicine-based therapy for gliomas should not be limited to cytotoxic agents, but also target the most important pathogenetic mechanisms, including cell differentiation pathways and angiogenesis. Moreover, the combinatorial approach of cell therapy plus nanomedicine strategies can open new therapeutical opportunities. The major part of attempted preclinical approaches on animal models involves active targeting with protein ligands, but, despite encouraging results, a few number of nanomedicines reached clinical trials, and most of them include drug-loaded nanocarriers free of targeting ligands, also because of safety and scalability concerns.

The Extracellular Matrix and Biocompatible Materials in Glioblastoma Treatment

During cancer genesis, the extracellular matrix (ECM) in the human brain undergoes important transformations, starting to resemble embryonic brain cell milieu with a much denser structure. However, the stiffness of the tumor ECM does not preclude cancer cells from migration. The importance of the ECM role in normal brain tissue as well as in tumor homeostasis has engaged much effort in trials to implement ECM as a target and an instrument in the treatment of brain cancers. This review provides a detailed analysis of both experimental and applied approaches in combined therapy for gliomas in adults. In general, matrix materials for glioma treatment should have properties facilitating the simplest delivery into the body. Hence, to deliver an artificial implant directly into the operation cavity it should be packed into a gel form, while for bloodstream injections matrix needs to be in the form of polymer micelles, nanoparticles, etc. Furthermore, the delivered material should mimic biomechanical properties of the native tissue, support vital functions, and slow down or stop the proliferation of surrounding cells for a prolonged period. The authors propose a two-step approach aimed, on the one hand, at elimination of remaining cancer cells and on the other hand, at restoring normal brain tissue. Thereby, the first bioartificial matrix to be applied should have relatively low elastic modulus should be loaded with anticancer drugs, while the second material with a higher elastic modulus for neurite outgrowth support should contain specific factors stimulating neuroregeneration.

Advances in bioinks and in vivo imaging of biomaterials for CNS applications

Due to increasing life expectancy incidence of neurological disorders is rapidly rising, thus adding urgency to develop effective strategies for treatment. Stem cell-based therapies were considered highly promising and while progress in this field is evident, outcomes of clinical trials are rather disappointing. Suboptimal engraftment, poor cell survival and uncontrolled differentiation may be the reasons behind dismal results. Clearly, new direction is needed and we postulate that with recent progress in biomaterials and bioprinting, regenerative approaches for neurological applications may be finally successful. The use of biomaterials aids engraftment of stem cells, protects them from harmful microenvironment and importantly, it facilitates the incorporation of cell-supporting molecules. The biomaterials used in bioprinting (the bioinks) form a scaffold for embedding the cells/biomolecules of interest, but also could be exploited as a source of endogenous contrast or supplemented with contrast agents for imaging. Additionally, bioprinting enables patient-specific customization with shape/size tailored for actual needs. In stroke or traumatic brain injury for example lesions are localized and focal, and usually progress with significant loss of tissue volume creating space that could be filled with artificial tissue using bioprinting modalities. The value of imaging for bioprinting technology is advantageous on many levels including design of custom shapes scaffolds based on anatomical 3D scans, assessment of performance and integration after scaffold implantation, or to learn about the degradation over time. In this review, we focus on bioprinting technology describing different printing techniques and properties of biomaterials in the context of requirements for neurological applications. We also discuss the need for in vivo imaging of implanted materials and tissue constructs reviewing applicable imaging modalities and type of information they can provide. STATEMENT OF SIGNIFICANCE: Current stem cell-based regenerative strategies for neurological diseases are ineffective due to inaccurate engraftment, low cell viability and suboptimal differentiation. Bioprinting and embedding stem cells within biomaterials at high precision, including building complex multi-material and multi-cell type composites may bring a breakthrough in this field. We provide here comprehensive review of bioinks, bioprinting techniques applicable to application for neurological disorders. Appreciating importance of longitudinal monitoring of implanted scaffolds, we discuss advantages of various imaging modalities available and suitable for imaging biomaterials in the central nervous system. Our goal is to inspire new experimental approaches combining imaging, biomaterials/bioinks, advanced manufacturing and tissue engineering approaches, and stimulate interest in image-guided therapies based on bioprinting.

Lipid nanocapsules as in vivo oxygen sensors using magnetic resonance imaging

Hypoxia is common occurrence of the tumour microenvironment, wherein heterogeneous gradients of O₂ give rise to tumoural cells which are highly malignant, metastatic, and resistant to therapeutic efforts. Thus, the assessment and imaging of hypoxia is essential for tumour diagnosis and treatment. Magnetic resonance imaging and, more specifically, the quantitative assessment of longitudinal relaxation time enhancement, was shown to enable the mapping of oxygen in tumours with increased sensitivity for lipids as compared to water signal. Unfortunately, this can only be applied to tumours with high lipid content. To overcome this issue, we propose the use of lipid nanocapsules (LNCs). LNCs have been demonstrated as excellent core-shell nanocarriers, wherein the lipidic-core is used for lipophilic drug encapsulation, enabling treatment of highly malignant tumours. Herein, however, we exploited the lipidic-core of the LNCs to develop a simple but effective technique to increase the lipidic content within tissues to enable the assessment and mapping of pO₂. LNCs were prepared using the phase-inversion technique to produce 60 nm sized nanoparticles, and in vitro studies demonstrated the permeability and responsiveness of LNCs to O₂. To evaluate the ability of LNCs to respond to changes in pO₂in vivo, after a hyperoxic challenge, three animal models, namely a normal tissue model (gastrocnemius muscle tissue) and two tumour tissue models (subcutaneous fibrosarcoma and intracerebral glioblastoma) were explored. LNCs were found to be responsive to variation of O₂in vivo. Moreover, the use of MRI enabled the mapping of oxygen gradients and heterogeneity within tumours.

Drug combination using an injectable nanomedicine hydrogel for glioblastoma treatment

Lauroyl-gemcitabine lipid nanocapsules (GemC₁₂-LNC) hydrogel, administered intratumorally or perisurgically in the tumor resection cavity, increases animal survival in several orthotopic GBM models. We hypothesized that GemC₁₂-LNC can be used as nanodelivery platform for other drugs, to obtain a combined local therapeutic approach for GBM. Paclitaxel (PTX) was selected as a model molecule and PTX-GemC₁₂-LNC formulation was evaluated in terms of physicochemical and mechanical properties. The PTX-GemC₁₂-LNC hydrogel stability and drug release were evaluated over time showing no significant differences compared to GemC₁₂-LNC. The drug combination was evaluated on several GBM cell lines showing increased cytotoxic activity compared to the original formulation and synergy between PTX and GemC₁₂. Our results suggest that GemC₁₂-LNC hydrogel can be used as nanodelivery platform for dual drug delivery to encapsulate active agents with different mechanisms of action to achieve a better antitumor efficacy against GBM or other solid tumors.