Positive-charged solid lipid nanoparticles as paclitaxel drug delivery system in glioblastoma treatment

A comprehensive review on lipid nanocarrier systems for cancer treatment: fabrication, future prospects and clinical trials

Over the last few decades, cancer has been considered a clinical challenge, being among the leading causes of mortality all over the world. Although many treatment approaches have been developed for cancer, chemotherapy is still the most utilized in the clinical setting. However, the available chemotherapeutics-based treatments have several caveats including their lack of specificity, adverse effects as well as cancer relapse and metastasis which mainly explains the low survival rate of patients. Lipid nanoparticles (LNPs) have been utilized as promising nanocarrier systems for chemotherapeutics to overcome the challenges of the currently applied therapeutic strategies for cancer treatment. Loading chemotherapeutic agent(s) into LNPs improves drug delivery at different aspects including specific targeting of tumours, and enhancing the bioavailability of drugs at the tumour site through selective release of their payload, thus reducing their undesired side effects on healthy cells. This review article delineates an overview of the clinical challenges in many cancer treatments as well as depicts the role of LNPs in achieving optimal therapeutic outcomes. Moreover, the review contains a comprehensive description of the many LNPs categories used as nanocarriers in cancer treatment to date, as well as the potential of LNPs for future applications in other areas of medicine and research.

Lipid-Based Nanocarriers in the Treatment of Glioblastoma Multiforme (GBM): Challenges and Opportunities

Glioblastoma multiforme (also known as glioblastoma; GBM) is one of the most malignant types of brain tumors that occurs in the CNS. Treatment strategies for glioblastoma are majorly comprised of surgical resection, radiotherapy, and chemotherapy along with combination therapy. Treatment of GBM is itself a tedious task but the involved barriers in GBM are one of the main impediments to move one step closer to the treatment of GBM. Basically, two of the barriers are of utmost importance in this regard, namely blood brain barrier (BBB) and blood brain tumor barrier (BBTB). This review will address different challenges and barriers in the treatment of GBM along with their etiology. The role and recent progress of lipid-based nanocarriers like liposomes, solid lipid nanocarriers (SLNs), nanostructured lipid carriers (NLCs), lipoplexes, and lipid hybrid carriers in the effective management of GBM will be discussed in detail.

Lipid Nanoparticles as a Promising Drug Delivery Carrier for Topical Ocular Therapy-An Overview on Recent Advances

Due to complicated anatomical and physical properties, targeted drug delivery to ocular tissues continues to be a key challenge for formulation scientists. Various attempts are currently being made to improve the in vivo performance of therapeutic molecules by encapsulating them in various nanocarrier systems or devices and administering them via invasive/non-invasive or minimally invasive drug administration methods. Biocompatible and biodegradable lipid nanoparticles have emerged as a potential alternative to conventional ocular drug delivery systems to overcome various ocular barriers. Lipid-based nanocarrier systems led to major technological advancements and therapeutic advantages during the last few decades of ocular therapy, such as high precorneal residence time, sustained drug release profile, minimum dosing frequency, decreased drug toxicity, targeted site delivery, and, therefore, an improvement in ocular bioavailability. In addition, such formulations can be given as fine dispersion in patient-friendly droppable preparation without causing blurred vision and ocular sensitivity reactions. The unique advantages of lipid nanoparticles, namely, solid lipid nanoparticles, nanostructured lipid carriers, nanoemulsions, and liposomes in intraocular targeted administration of various therapeutic drugs are extensively discussed. Ongoing and completed clinical trials of various liposome-based formulations and various characterization techniques designed for nanoemulsion in ocular delivery are tabulated. This review also describes diverse solid lipid nanoparticle preparation methods, procedures, advantages, and limitations. Functionalization approaches to overcome the drawbacks of lipid nanoparticles, as well as the exploration of new functional additives with the potential to improve the penetration of macromolecular pharmaceuticals, would quickly progress the challenging field of ocular drug delivery systems.

Nose-to-brain delivery of simvastatin mediated by chitosan-coated lipid-core nanocapsules allows for the treatment of glioblastoma in vivo

Glioblastoma is the most common and lethal malignant brain tumor. Despite simvastatin (SVT) showing potential anticancer properties, its antitumoral effect against glioblastoma appears limited when the conventional oral administration route is selected. As a consequence, nose-to-brain delivery has been proposed as an alternative route to deliver SVT into the brain. This study aimed to prepare chitosan-coated simvastatin-loaded lipid-core nanocapsules (LNC_SVT-chit) suitable for nose-to-brain delivery and capable of fostering antitumor effects against glioblastoma both in vitro and in vivo. Results showed that the nanocapsules present adequate particle size (mean diameter below 200 nm), narrow particle size distribution (PDI < 0.2), positive zeta potential and high encapsulation efficiency (nearly 100%). In vitro cytotoxicity of LNC_SVT-chit was comparable to non-encapsulated SVT in C6 rat glioma cells, whereas LNC_SVT-chit were more cytotoxic than non-encapsulated SVT after 72 h of incubation against U-138 MG human glioblastoma cell line. In studies carried out in rats, LNC_SVT-chit significantly enhanced the amount of drug in rat brain tissue after intranasal administration (2.4-fold) when compared with free SVT. Moreover, LNC_SVT-chit promoted a significant decrease in tumor growth and malignancy in glioma-bearing rats in comparison to control and free SVT groups. Additionally, LNC_SVT-chit did not cause any toxicity in treated rats. Considered overall, the results demonstrated that the nose-to-brain administration of LNC_SVT-chit represents a novel potential strategy for glioblastoma treatment.

Engineered Solid Lipid Nanoparticles and Nanostructured Lipid Carriers as New Generations of Blood-Brain Barrier Transmitters

The blood-brain barrier (BBB) is considered as the most challenging barrier in brain drug delivery. Indeed, there is a definite link between the BBB integrity defects and central nervous systems (CNS) disorders, such as neurodegenerative diseases and brain cancers, increasing concerns in the contemporary era because of the inability of most therapeutic approaches. Solid lipid nanoparticles (SLNs) and nanostructured lipid carriers (NLCs) have already been identified as having several advantages in facilitating the transportation of hydrophilic and hydrophobic agents across the BBB. This review first explains BBB functions and its challenges in brain drug delivery, followed by a brief description of nanoparticle-based drug delivery for brain diseases. A detailed presentation of recent progressions in optimizing SLNs and NLCs for controlled release drug delivery, gene therapy, targeted drug delivery, and diagnosis of neurodegenerative diseases and brain cancers is approached. Finally, the problems, challenges, and future perspectives in optimizing these carriers for potential clinical application were described briefly.

Lipid nanostructures for targeting brain cancer

Advancements in both material science and bionanotechnology are transforming the health care sector. To this end, nanoparticles are increasingly used to improve diagnosis, monitoring, and therapy. Huge research is being carried out to improve the design, efficiency, and performance of these nanoparticles. Nanoparticles are also considered as a major area of research and development to meet the essential requirements for use in nanomedicine where safety, compatibility, biodegradability, biodistribution, stability, and effectiveness are requirements towards the desired application. In this regard, lipids have been used in pharmaceuticals and medical formulations for a long time. The present work focuses on the use of lipid nanostructures to combat brain tumors. In addition, this review summarizes the literature pertaining to solid lipid nanoparticles (SLN) and nanostructured lipid carriers (LNC), methods of preparation and characterization, developments achieved to overcome blood brain barrier (BBB), and modifications used to increase their effectiveness.

Improving temozolomide biopharmaceutical properties in glioblastoma multiforme (GBM) treatment using GBM-targeting nanocarriers

Glioblastoma multiforme (GBM) is the most common primary brain cancer. GBM has aggressive development, and the pharmacological treatment remains a challenge due to GBM anatomical characteristics' (the blood-brain barrier and tumor microenvironment) and the increasing resistance to marketed drugs, such as temozolomide (TMZ), the first-line drug for GBM treatment. Due to physical-chemical properties such as short half-life time and the increasing resistance shown by GBM cells, high doses and repeated administrations are necessary, leading to significant adverse events. This review will discuss the main molecular mechanisms of TMZ resistance and the use of functionalized nanocarriers as an efficient and safe strategy for TMZ delivery. GBM-targeting nanocarriers are an important tool for the treatment of GBM, demonstrating to improve the biopharmaceutical properties of TMZ and repurpose its use in anti-GBM therapy. Technical aspects of nanocarriers will be discussed, and biological models highlighting the advantages and effects of functionalization strategies in TMZ anti-GBM activity. Finally, conclusions regarding the main findings will be made in the context of new perspectives for the treatment of GBM using TMZ as a chemotherapy agent, improving the sensibility and biological anti-tumor effect of TMZ through functionalization strategies.

Influence of lipid matrix composition on biopharmaceutical properties of lipid nanoparticles

Lipid nanoparticles (LN) were invented in the early 1990ties and can be exploited for oral and topical drug delivery to increase the bioavailability of lipophilic active compounds. The lipid matrix of the LN can be composed of solid lipids or of a mixture of liquid and solid lipids. The influence of the lipid matrix composition of LN on the dermal penetration efficacy is not known and was therefore investigated in this study. For this the whole spectrum of LN, that means NE (100% liquid lipid), SLN (100% solid lipid) and NLC that contained low, medium and high amounts of oil were produced and characterized in regard to size, zeta potential, crystallinity and in-vitro release. In addition, the dermal penetration efficacy was determined ex-vivo and the bio-physical skin parameters, i.e., spreadability on skin, skin hydration, skin friction and transepidermal water loss were also assessed. Results demonstrate the tremendous influence of the lipid matrix composition on the biopharmaceutical properties of the LN but showed only minor differences in the physico-chemical properties of the particles. The physico-chemical properties of the LN and the in-vitro release data were not clearly linked to the dermal penetration efficacy, because also other parameters, e.g., skin hydration, spreadability of the formulation on skin and/or film formation of the LN on skin were found to be important parameters that influence the dermal penetration efficacy. Therefore, to allow for the development of effective LN formulations with tailor-made biopharmaceutical properties, not only the physico-chemical properties and in-vitro drug release profiles but also the most relevant biopharmaceutical properties of the LN should be assessed during the formulation development of LN.

Solid Lipid Nanoparticles (SLNs): An Advanced Drug Delivery System Targeting Brain through BBB

The blood-brain barrier (BBB) plays a vital role in the protection and maintenance of homeostasis in the brain. In this way, it is an interesting target as an interface for various types of drug delivery, specifically in the context of the treatment of several neuropathological conditions where the therapeutic agents cannot cross the BBB. Drug toxicity and on-target specificity are among some of the limitations associated with current neurotherapeutics. In recent years, advances in nanodrug delivery have enabled the carrier system containing the active therapeutic drug to target the signaling pathways and pathophysiology that are closely linked to central nervous system (CNS) disorders such as Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease (HD), multiple sclerosis (MS), brain tumor, epilepsy, ischemic stroke, and neurodegeneration. At present, among the nano formulations, solid lipid nanoparticles (SLNs) have emerged as a putative drug carrier system that can deliver the active therapeutics (drug-loaded SLNs) across the BBB at the target site of the brain, offering a novel approach with controlled drug delivery, longer circulation time, target specificity, and higher efficacy, and more importantly, reducing toxicity in a biomimetic way. This paper highlights the synthesis and application of SLNs as a novel nontoxic formulation strategy to carry CNS drugs across the BBB to improve the use of therapeutics agents in treating major neurological disorders in future clinics.

A Composite Nanosystem as a Potential Tool for the Local Treatment of Glioblastoma: Chitosan-Coated Solid Lipid Nanoparticles Embedded in Electrospun Nanofibers

Glioblastoma multiforme (GBM) is one of the most prevalent and aggressive brain tumors for which there is currently no cure. A novel composite nanosystem (CN), consisting of chitosan-coated Solid Lipid Nanoparticles (c-SLN) embedded in O-carboxymethyl chitosan (O-CMCS)-containing nanofibers (NFs), was proposed as a potential tool for the local delivery of lipophilic anti-proliferative drugs. Coacervation was selected as a solvent-free method for the preparation of stearic acid (SA) and behenic acid (BA)-based SLN (SA-SLN and BA-SLN respectively). BA-SLN, containing 0.75% w/w BA sodium salt and 3% w/w poly(vinyl alcohol) (PVA), were selected for the prosecution of the work since they are characterized by the lowest size functional to their subsequent coating and incorporation in nanofibers. BA-SLN were coated with chitosan (CS) by means of a two-step coating method based on the physical absorption of positively charged CS chains on the SLN negative surface. Nile Red (NR), chosen as the hydrophobic model dye, was dissolved in a micellar solution of BA sodium salt and then added with a coacervating solution until pH ≅ 2.5 was reached. Immunocytochemistry analyses highlighted that CS-coated BA-SLN (c-BA-SLN) exhibited a higher accumulation in human glioblastoma cells (U-373) after 6 h than CS-free BA-SLN. Finally, the c-BA-SLN dispersion was blended with a solution consisting of freely soluble polymers (O-CMCS, poly(ethylene oxide) and poloxamer) and then electrospun to obtain NFs with a mean diameter equal to 850 nm. After the NFs dissolution in an aqueous media, c-BA-SLN maintained their physicochemical properties and zeta potential.

A New Bevacizumab Carrier for Intravitreal Administration: Focus on Stability

Bevacizumab (BVZ) is a monoclonal antibody that binds to human vascular endothelial growth factor A (VEGF-A) and inhibits the interaction between VEGF-A and VEGF receptors, thus blocking the angiogenesis. Repeated intravitreal injections of BVZ for the treatment of ocular pathologies that present an excessive proliferation results in a low patience compliance. BVZ is specially indicated for the treatment of diabetic and degenerative retinopathy. In the present study, we designed lipid nanoparticles (NPs) as a BVZ sustained drug delivery system for reducing the frequency of administration. We used a simple and highly efficient procedure, “Cold dilution of microemulsions”, to obtain spherical NPs with mean diameters of 280–430 nm, Zeta potentials between −17 and −31 mV, and drug entrapment efficiencies between 50 to 90%. This study focused on the biochemical and biophysical stabilities of BVZ after entrapment in NPs. SDS-PAGE electrophoretic analysis and circular dichroism, dynamic light scattering, and scanning electron microscopy were used to characterize BVZ-loaded NPs. The biocompatibility was assessed by in vitro cell compatibility studies using the ARPE-19 cell line. Thus, in this work, a stable BVZ-loaded system was obtained. In addition, several studies have shown that BVZ is released slowly from the lipid matrix and that this system is biocompatible. The results are promising and the developed NPs could be exploited to create a new, potentially effective and minimally invasive treatment of intraocular diseases.

Preparation of cetyl palmitate-based PEGylated solid lipid nanoparticles by microfluidic technique

In recent years, several studies have shown that the use of solid lipid nanoparticles (SLN) as a colloidal drug delivery system was more advantageous than lipid emulsions, liposomes and polymeric nanoparticles. SLNs have numerous advantages of different nanosystems and rule out many of their drawbacks. Despite the numerous advantages of SLNs, translation from the preclinical formulation to the industrial scale-up is limited. In order to provide a reproducible and reliable method of producing nanoparticles, and thus, obtain an industrial scale-up, several methods of synthesis of nanoparticles by microfluidic have been developed. Microfluidic technique allows a good control and a continuous online synthesis of nanosystems compared to synthesis in bulk, leading to a narrow size distribution, high batch-to-batch reproducibility, as well as to the industrial scale-up feasibility. This work described the optimization process to produce SLNs by microfluidics. The SLNs produced by microfluidics were characterized by complementary optical and morphological techniques and compared with those produced by bulk method. SLNs were loaded with paclitaxel and sorafenib, used as model drugs. The anti-cancer efficiency of the SLNs formulation was estimated with 2D and 3D tumour models of two different cell lines, and the cellular uptake was also studied with fluorescence-assisted measurements.

Preparation of Solid Lipid Nanoparticles and Nanostructured Lipid Carriers for Drug Delivery and the Effects of Preparation Parameters of Solvent Injection Method

Solid lipid nanoparticles (SLNs) and nanostructured lipid carriers (NLCs) have emerged as potential drug delivery systems for various applications that are produced from physiological, biodegradable, and biocompatible lipids. The methods used to produce SLNs and NLCs have been well investigated and reviewed, but solvent injection method provides an alternative means of preparing these drug carriers. The advantages of solvent injection method include a fast production process, easiness of handling, and applicability in many laboratories without requirement of complicated instruments. The effects of formulations and process parameters of this method on the characteristics of the produced SLNs and NLCs have been investigated in several studies. This review describes the methods currently used to prepare SLNs and NLCs with focus on solvent injection method. We summarize recent development in SLNs and NLCs production using this technique. In addition, the effects of solvent injection process parameters on SLNs and NLCs characteristics are discussed.

The in vivo toxicological profile of cationic solid lipid nanoparticles

Cationic solid lipid nanoparticles (cSLNs) are considered as one of the most effective lipid nanocarriers for delivery of low water-solubility compounds and genetic materials. As the excipients used in the cSLN production are generally regarded as safe (GRAS), the formulations are granted as non-toxic. However, the toxicological profile of new SLN-based formulations should always be performed to confirm that the delivery systems themselves may not impose risks to the human health. Therefore, in this study, we delineate the toxicological profile of the cSLN formulation at 24 and 72 h after single intravenous injection to male Wistar rats. Hematological, biochemical, and histopathological evaluations of the spleen, lungs, liver, and kidneys indicated short-lived alterations including neutrophilia. We found increases in the population of macrophages in the lungs, liver, and spleen and also migration of circulating neutrophils into inflamed tissue and a decrease in blood urea nitrogen. We also observed the presence of cSLNs within the brain parenchyma without any sign of damage to the blood-brain barrier. These side effects appeared to be mild and transitory (< 72 h). These findings reinforce the importance of investigating the toxicity of SLN-based formulations before the incorporation of drugs/genetic material to the formulation and its translation to the clinic.

A Reevaluation of Chitosan-Decorated Nanoparticles to Cross the Blood-Brain Barrier

The blood-brain barrier (BBB) is a sophisticated and very selective dynamic interface composed of endothelial cells expressing enzymes, transport systems, and receptors that regulate the passage of nutrients, ions, oxygen, and other essential molecules to the brain, regulating its homeostasis. Moreover, the BBB performs a vital function in protecting the brain from pathogens and other dangerous agents in the blood circulation. Despite its crucial role, this barrier represents a difficult obstacle for the treatment of brain diseases because many therapeutic agents cannot cross it. Thus, different strategies based on nanoparticles have been explored in recent years. Concerning this, chitosan-decorated nanoparticles have demonstrated enormous potential for drug delivery across the BBB and treatment of Alzheimer's disease, Parkinson's disease, gliomas, cerebral ischemia, and schizophrenia. Our main objective was to highlight the high potential of chitosan adsorption to improve the penetrability through the BBB of nanoformulations for diseases of CNS. Therefore, we describe the BBB structure and function, as well as the routes of chitosan for crossing it. Moreover, we define the methods of decoration of nanoparticles with chitosan and provide numerous examples of their potential utilization in a variety of brain diseases. Lastly, we discuss future directions, mentioning the need for extensive characterization of proposed nanoformulations and clinical trials for evaluation of their efficacy.

Formulating SLN and NLC as Innovative Drug Delivery Systems for Non-Invasive Routes of Drug Administration

Colloidal carriers diverge depending on their composition, ability to incorporate drugs and applicability, but the common feature is the small average particle size. Among the carriers with the potential nanostructured drug delivery application there are SLN and NLC. These nanostructured systems consist of complex lipids and highly purified mixtures of glycerides having varying particle size. Also, these systems have shown physical stability, protection capacity of unstable drugs, release control ability, excellent tolerability, possibility of vectorization, and no reported production problems related to large-scale. Several production procedures can be applied to achieve high association efficiency between the bioactive and the carrier, depending on the physicochemical properties of both, as well as on the production procedure applied. The whole set of unique advantages such as enhanced drug loading capacity, prevention of drug expulsion, leads to more flexibility for modulation of drug release and makes Lipid-based nanocarriers (LNCs) versatile delivery system for various routes of administration. The route of administration has a significant impact on the therapeutic outcome of a drug. Thus, the non-invasive routes, which were of minor importance as parts of drug delivery in the past, have assumed added importance drugs, proteins, peptides and biopharmaceuticals drug delivery and these include nasal, buccal, vaginal and transdermal routes. The objective of this paper is to present the state of the art concerning the application of the lipid nanocarriers designated for non-invasive routes of administration. In this manner, this review presents an innovative technological platform to develop nanostructured delivery systems with great versatility of application in non-invasive routes of administration and targeting drug release.

Delivery across the blood-brain barrier: nanomedicine for glioblastoma multiforme

The malignant brain cancer, glioblastoma multiforme (GBM), is heterogeneous, infiltrative, and associated with chemo- and radioresistance. Despite pharmacological advances, prognosis is poor. Delivery into the brain is hampered by the blood-brain barrier (BBB), which limits the efficacy of both conventional and novel therapies at the target site. Current treatments for GBM remain palliative rather than curative; therefore, innovative delivery strategies are required and nanoparticles (NPs) are at the forefront of future solutions. Since the FDA approval of Doxil® (1995) and Abraxane (2005), the first generation of nanomedicines, development of nano-based therapies as anti-cancer treatments has escalated. A new generation of NPs has been investigated to efficiently deliver therapeutic agents to the brain, overcoming the restrictive properties of the BBB. This review discusses obstacles encountered with systemic administration along with integration of NPs incorporated with conventional and emerging treatments. Barriers to brain drug delivery, NP transport mechanisms across the BBB, effect of opsonisation on NPs administered systemically, and peptides as NP systems are addressed.

Nose-to-brain delivery of antiglioblastoma drugs embedded into lipid nanocarrier systems: status quo and outlook

Glioblastoma multiforme (GBM) is one of the most devastating and deadly types of tumor. Among all the present treatment strategies, the utmost prerequisite is prolonged intervention at the malignant site. The blood-brain barrier (BBB) is the bottleneck in the delivery of anti-GBM drugs and invasive treatment comes with many pitfalls. This review will discuss the potential of embedding antitumor drugs into nanocarriers for intranasal delivery. Additionally, it emphasizes the significance of applying quality by design (QbD) methodology from the early development stages to ensure the high quality, safety and efficacy of the developed carrier system.

Engineering Tumor-Targeting Nanoparticles as Vehicles for Precision Nanomedicine

As a nascent and emerging field that holds great potential for precision oncology, nanotechnology has been envisioned to improve drug delivery and imaging capabilities through precise and efficient tumor targeting, safely sparing healthy normal tissue. In the clinic, nanoparticle formulations such as the first-generation Abraxane® in breast cancer, Doxil® for sarcoma, and Onivyde® for metastatic pancreatic cancer, have shown advancement in drug delivery while improving safety profiles. However, effective accumulation of nanoparticles at the tumor site is sub-optimal due to biological barriers that must be overcome. Nanoparticle delivery and retention can be altered through systematic design considerations in order to enhance passive accumulation or active targeting to the tumor site. In tumor niches where passive targeting is possible, modifications in the size and charge of nanoparticles play a role in their tissue accumulation. For niches in which active targeting is required, precision oncology research has identified targetable biomarkers, with which nanoparticle design can be altered through bioconjugation using antibodies, peptides, or small molecule agonists and antagonists. This review is structured to provide a better understanding of nanoparticle engineering design principles with emphasis on overcoming tumor-specific biological barriers.

Paclitaxel incorporated exosomes derived from glioblastoma cells: comparative study of two loading techniques

BACKGROUND

Exosomes are natural nanoparticles that are involved in intercellular communication via transferring molecular information between cells. Recently, exosomes have been considered for exploitation as novel drug delivery systems due to their specific properties for carrying specific molecules and surface proteins.

METHODS

In this study, U-87 cell derived exosomes have been investigated for delivery of a potent chemotherapeutic agent, paclitaxel (PTX). Two methods of loading were utilized to incorporate PTX in exosomes and the exosomes pharmaceutical and cytotoxic characterizations were determined.

RESULTS

The drug loaded and empty exosomes were found to have particle size of 50-100 nm and zeta potential of ≈ - 20 mV. Loading capacity of 7.4 ng and 9.2 ng PTX into 1 μg of exosome total protein were also measured for incubation and sonication methods, respectively. Incorporation of PTX into exosomes significantly increased its cytotoxicity against U-87 cell line (59.92% cell viability) while it was found that the empty exosomes exhibited cell viability of 91.98%.

CONCLUSIONS

Loading method could affect the loading capacity of exosomes and their encapsulated chemotherapeutic molecule showed higher cytotoxicity into exosomes. These results promise exosomes as appropriate drug delivery system for glioblastoma multiform (GBM) treatment.

Brain targeted delivery of anticancer drugs: prospective approach using solid lipid nanoparticles

A brain tumour is amongst most devastating and challenging condition to overcome with suitable treatment as the drug has to cross the blood-brain barrier (BBB) with several physiological barriers like opsonisation by the reticuloendothelial system. Presently various techniques such as surgical, chemotherapeutic agents, and radiotherapy techniques have performed to extend the lifespan of patients diagnosed with glioblastoma, which did not maximise the overall survival of patients with a tumour. Nanotechnology is relied upon to diminish the requirement for intrusive methods for conveyance of therapeutics to the central nervous system. Colloidal nanocarriers sizing range 1-1000 nm have been utilised to cross BBB delivers the drug at cell levels with enhanced bioavailability and reduced toxicity. However, solid lipid nanoparticles (SLNs) are considered a highly flexible carrier for more successful remedially in brain tumour. The treatment of a brain tumour via SLNs is gaining greater potency due to its inimitable size and lipidic nature. This review focuses and represents the current strategies of SLNs in the brain tumour treatment with appropriate techniques adopted are highlighted. Based on this review, the authors concluded that SLNs embrace exclusive promising lipidic nanocarrier that could be utilised to target a brain tumour effectively.

Overcoming the Blood–Brain Barrier. Challenges and Tricks for CNS Drug Delivery

Treatment of certain central nervous system disorders, including different types of cerebral malignancies, is limited by traditional oral or systemic administrations of therapeutic drugs due to possible serious side effects and/or lack of the brain penetration and, therefore, the efficacy of the drugs is diminished. During the last decade, several new technologies were developed to overcome barrier properties of cerebral capillaries. This review gives a short overview of the structural elements and anatomical features of the blood–brain barrier. The various in vitro (static and dynamic), in vivo (microdialysis), and in situ (brain perfusion) blood–brain barrier models are also presented. The drug formulations and administration options to deliver molecules effectively to the central nervous system (CNS) are presented. Nanocarriers, nanoparticles (lipid, polymeric, magnetic, gold, and carbon based nanoparticles, dendrimers, etc.), viral and peptid vectors and shuttles, sonoporation and microbubbles are briefly shown. The modulation of receptors and efflux transporters in the cell membrane can also be an effective approach to enhance brain exposure to therapeutic compounds. Intranasal administration is a noninvasive delivery route to bypass the blood–brain barrier, while direct brain administration is an invasive mode to target the brain region with therapeutic drug concentrations locally. Nowadays, both technological and mechanistic tools are available to assist in overcoming the blood–brain barrier. With these techniques more effective and even safer drugs can be developed for the treatment of devastating brain disorders.

Stearoyl-Chitosan Coated Nanoparticles Obtained by Microemulsion Cold Dilution Technique

Chitosan is an excipient which has been studied thoroughly in research works thanks to its positive characteristics such as muco-adhesiveness and ability to open epithelial-tight-junctions. In this article, lipophilic stearoyl chitosan (ST-CS) was synthetized in order to anchor this polymer to lipid nanoparticles and prepare ST-CS-coated nanoparticles (ST-CS-NP) using the microemulsion cold dilution technique. Curcumin (CURC) was used as model drug. CURC-ST-CS-NP were characterized by dimensional analysis, zeta potential, drug entrapment, drug release; tested in vitro on Human Umbilical Vein Endothelial Cell (HUVEC) cells to study its cytotoxicity and on human pancreatic cancer cells (PANC-1) to determine inhibition ability; tested in rats to determine CURC blood profiles and biodistribution. CURC-ST-CS-NP had mean diameters in the range 200–400 nm and CURC entrapment up to 73%. These systems did not show cytotoxicity on HUVEC cells at all tested dilutions and revealed to be more effective than free CURC solution on PANC-1 cells at 5 and 10 µM CURC. Blood profile studies evidenced as CURC entrapment in NP prolonged the permanence of drug in the systemic circulation compared to CURC solution due to a certain stealth property of NP, probably attributable to hydrophilic chitosan coating. Biodistribution studies showed a smaller CURC concentration in RES organs when CURC-ST-CS-NP were administered.

The therapeutic effect in gliomas of nanobubbles carrying siRNA combined with ultrasound-targeted destruction

Background

Nanobubbles (NBs) combined with ultrasound-targeted destruction (UTD) have become promising potential carriers for drug or siRNA delivery. Due to their nano-size, NBs could penetrate tumor blood vessels and accumulate in intercellular spaces so that "sonoporation" induced by UTD would act directly on the tumor cells to increase cell membrane permeability.

Methods

Based on the successful the fabrication of NBs, we synthesized NBs carrying siRNA (NBs-siRNA) by using a biotin-streptavidin system. We then utilized ultrasound irradiation (UI)-targeted NBs-siRNA to improve siRNA transfection and achieve the inhibition of glioma growth.

Results

NBs as carriers combined with UI effectively enhanced siRNA transfection and the effect of silencing targeted genes in vitro. Additionally, a better therapeutic effect was shown in the NBs-siRNA with UI group in vivo compared with that of microbubbles (MBs) with UI or NBs-siRNA without UI.

Conclusion

These results indicated that NBs combined with UTD might be an ideal delivery vector for siRNA to achieve the noninvasive treatment of glioma.

RGD peptide-modified, paclitaxel prodrug-based, dual-drugs loaded, and redox-sensitive lipid-polymer nanoparticles for the enhanced lung cancer therapy

One approach to improve the targeted therapeutic efficiency of lung cancer is to deliver drugs using nano-scaled systems. In this study, RGD peptide-modified, paclitaxel (PTX) prodrug-based, dual-drugs loaded, and redox-sensitive lipid-polymer nanoparticles were developed and the in vitro and in vivo antitumor efficiency was evaluated in lung cancer cells and tumor bearing animal models. RGD-modified PTX and cisplatin (CDDP) loaded LPNs (RGD-ss-PTX/CDDP LPNs) have sizes around 190 nm, and zeta potentials of -35 mV. The half-maximal inhibitory concentration (IC50) values were 26.7 and 75.3 μg/mL for drugs loaded LPNs and free drugs combination, which indicates significantly higher antitumor activity of LPNs than free drugs. RGD-ss-PTX/CDDP LPNs also exhibited the best antitumor efficiency in vivo, which inhibited the tumor size of mice from 1486 mm³ to 263 mm³. The results illustrated that the system could successfully load drugs and achieve synergistic combination lung cancer treatment efficiency with lower systemic toxicity compared with free drugs counterparts. The resulting system could be facilitated as a promising targeted nanomedicine for the treatment of lung cancer.

Gene delivery in the cornea: in vitro & ex vivo evaluation of solid lipid nanoparticle-based vectors

AIM

Inflammation is a process that underlies sight-threatening ocular surface diseases, and gene supplementation with the plasmid that encodes for p-IL10 will allow the sustained de novo synthesis of the cytokine to occur in corneal cells, and provide a long-term anti-inflammatory effect. This work describes the development of solid lipid nanoparticle systems for the delivery of p-IL10 to transfect the cornea.

RESULTS

In vitro, vectors showed suitable features as nonviral vectors (size, ζ-potential, DNA binding, protection and release), and they were able to enter and transfect human corneal epithelial cells. Ex vivo, the vectors were found to transfect the epithelium, the stroma and the endothelium in rabbit corneal explants. Distribution of gene expression within the cell layers of the cornea depended on the composition of the four vectors evaluated.

CONCLUSION

Solid lipid nanoparticle-based vectors are promising gene delivery systems for corneal diseases, including inflammation.

Lactoferrin- and RGD-comodified, temozolomide and vincristine-coloaded nanostructured lipid carriers for gliomatosis cerebri combination therapy

PURPOSE

Glioblastoma multiforme (GBM) is the most common malignant brain tumor originating in the central nervous system in adults. Based on nanotechnology such as liposomes, polymeric nanoparticles, and lipid nanoparticles, recent research efforts have been aimed to target drugs to the brain.

METHODS

In this study, lactoferrin- and arginine-glycine-aspartic acid (RGD) dual- ligand-comodified, temozolomide and vincristine-coloaded nanostructured lipid carriers (L/RT/V-NLCs) were introduced for GBM combination therapy. The physicochemical properties of L/R-T/V-NLCs such as particle size, zeta potential, and encapsulated efficiency are measured. The drug release profile, cellular uptake, cytotoxicity, tissue distribution, and antitumor activity of L/R-T/V-NLCs are further investigated in vitro and in vivo.

RESULTS

L/R-T/V-NLCs were stable with nanosize and high drug encapsulation efficiency. L/R-T/V-NLCs exhibited sustained-release behavior, high cellular uptake, high cytotoxicity and synergy effects, increased drug accumulation in the tumor tissue, and obvious tumor inhibition efficiency with low systemic toxicity.

CONCLUSION

L/R-T/V-NLCs could be a promising drug delivery system for glioblastoma chemotherapy.

Paclitaxel Treatment and Proprotein Convertase 1/3 (PC1/3) Knockdown in Macrophages is a Promising Antiglioma Strategy as Revealed by Proteomics and Cytotoxicity Studies

High grade gliomas are the most common brain tumors in adult. These tumors are characterized by a high infiltration in microglial cells and macrophages. The immunosuppressive tumor environment is known to orient immune cells toward a pro-tumoral and anti-inflammatory phenotype. Therefore, the current challenge for cancer therapy is to find a way to reorient macrophages toward an antitumoral phenotype. Previously, we demonstrated that macrophages secreted antitumoral factors when they were invalidated for the proprotein converstase 1/3 (PC1/3) and treated with LPS. However, achieving an activation of macrophages via LPS/TLR4/Myd88-dependent pathway appears yet unfeasible in cancer patients. On the contrary, the antitumor drug Paclitaxel is also known to activate the TLR4 MyD88-dependent signaling pathway and mimics LPS action. Therefore, we evaluated if PC1/3 knock-down (KD) macrophages could be activated by Paclitaxel and efficient against glioma. We report here that such a treatment of PC1/3 KD macrophages drove to the overexpression of proteins mainly involved in cytoskeleton rearrangement. In support of this finding, we found that these cells exhibited a Ca²⁺ increase after Paclitaxel treatment. This is indicative of a possible depolymerization of microtubules and may therefore reflect an activation of inflammatory pathways in macrophages. In such a way, we found that PC1/3 KD macrophages displayed a repression of the anti-inflammatory pathway STAT3 and secreted more pro-inflammatory cytokines. Extracellular vesicles isolated from these PC1/3 KD cells inhibited glioma growth. Finally, the supernatant collected from the coculture between glioma cells and PC1/3 KD macrophages contained more antitumoral factors. These findings unravel the potential value of a new therapeutic strategy combining Paclitaxel and PC1/3 inhibition to switch macrophages toward an antitumoral immunophenotype.

Role of GABAB receptors and p38MAPK/NF-κB pathway in paclitaxel-induced apoptosis of hippocampal neurons

CONTEXT

The effects of the anticancer drug paclitaxel on learning and memory are rarely studied.

OBJECTIVE

This study investigated changes in GABAB receptor expression during paclitaxel-induced apoptosis of hippocampal neurons and the role of the p38MAPK/NF-κB pathway in this process.

MATERIALS AND METHODS

Hippocampal neurons isolated from neonatal Sprague-Dawley rats were divided into six groups: Control (C), SB (10 µL of 10-µmol/L SB203580), SN (53 µg/mL SN50), N (1 µmol/L paclitaxel), SB + N (10 µmol/L SB203580 + 1 µmol/L paclitaxel) and SN + N (53 µg/mL SN50 + 1 µmol/L paclitaxel). Cells in different groups were treated with corresponding agents for 24 h at 37 °C. The apoptosis rate and protein levels of GABAB1 receptors and NF-κB p65 were evaluated. Rat models of neuropathic pain was induced by paclitaxel and were divided into four groups such as N, B + N, SN + N and SN + B + N groups. Rats in the N group received intrathecal injections of normal saline solution. Rats in the B + N group received intrathecal injections of 10 μL baclofen (0.05 μg/μL). Rats in the SN + N and SN + B + N groups received intrathecal injections of SN50 and SN50 plus baclofen, respectively. Spatial learning and memory were evaluated in rat models based on the escape latency and the number of crossings over the platform and protein levels of GABAB1 receptors, NF-κB, IL-1β and TNFα were measured by immunohistochemistry assay and western blot.

RESULTS

The neuronal apoptosis rate was significantly increased in N (49.16 ± 3.12)%, SB + N (31.18 ± 3.02)% and SN + N (28.47 ± 3.75)% groups, accompanied by increased levels of GABAB1 receptors and NF-κB p65 (p < 0.05). The paclitaxel-treated rats demonstrated significantly increased latency (24.32 ± 2.94)s and decreased the crossings number (3.14 ± 0.63) after 15 d in the Morris water maze (p < 0.05). Immunohistochemistry assay showed that compared with the N group (GABAB1:9.0 ± 1.6, NF-κB p65:29.6 ± 2.4, IL-1β: 30.4 ± 3.4, TNFα: 31.0 ± 3.4), B + N, SN + N and SN + B + N groups evidently increased levels of GABAB1 receptor (B + N:SN + N:SN + B + N = 19.4 ± 2.1:20.8 ± 1.9:28.0 ± 1.9) but significantly decreased levels of NF-κB p65 (B + N:SN + N:SN + B + N = 21.2 ± 1.5:18.6 ± 2.1:12.6 ± 1.5), IL-1β (B + N:SN + N:SN + B + N = 22.0 ± 1.0:19.6 ± 1.8:14.6 ± 1.5) and TNF α (B + N:SN + N:SN + B + N = 23.0 ± 1.6:22.2 ± 0.8:16.6 ± 1.7). Similar findings were found in western blot analysis.

DISCUSSIONS AND CONCLUSIONS

Paclitaxel may reduce cognitive function in rats through the p38MAPK/NF-κB pathway and GABAB1 receptors.

Glycol chitosan functionalized asenapine nanostructured lipid carriers for targeted brain delivery: Pharmacokinetic and teratogenic assessment

Blood brain barrier (BBB) is a complex, tight barrier between endothelial cells of cerebral blood vessels. It acts as a physical barrier and provides access to only those moieties which are necessary for proper brain functioning. However, this selective prudence also acts as a hindrance in therapeutic targeting of brain necessitating pharmaceutical intervention. Intranasal drug delivery is one such approach which we have exploited here for targeted brain delivery of asenapine by glycol chitosan coated nanostructured lipid carrier (GC-ANLC). The best formulation was characterized for particle size (184.2±5.59nm), zeta potential (18.83±1.18mV), entrapment efficiency (83.52±2.59%) and surface morphology (spherical and smooth). In-vitro drug-release study showed that Higuchi model (r²=0.9938, AIC=52.94) dictated asenapine release from GC-ANLC. Cell compatibility study suggested biocompatibility of GC-ANLC with A549 cell line as well as nasal epithelial cell membrane. After intranasal delivery, Charles-Foster rats demonstrated approximately 2.3 and 4 fold higher systemic and brain bioavailability of GC-ANLC compared to asenapine solution (ASM). Embryo fetal toxicity study was further conducted to investigate the teratogenic effect of GC-ANLC. In conclusion, prepared GC-ANLC could be used as a promising drug carrier for delivery of asenapine via intranasal route with better pharmacokinetic and safety profile.

Advances in the design of solid lipid nanoparticles and nanostructured lipid carriers for targeting brain diseases

Solid lipid nanoparticles (SLNs) and nanostructured lipid carriers (NLCs) comprise a category of versatile drug delivery systems that have been used in the biomedical field for >25years. SLNs and NLCs have been used for the treatment of various diseases including cardiovascular and cerebrovascular, and are considered a standard treatment for the latter, due to their inherent ability to cross the blood brain barrier (BBB). In this review, a presentation of the most important brain diseases (brain cancer, ischemic stroke, Alzheimer's disease, Parkinson's disease and multiple sclerosis) is approached, followed by the basic fabrication techniques of SLNs and NLCs. A detailed description of the reported studies of the last seven years, of active and passive targeting SLNs and NLCs for the treatment of glioblastoma multiforme and of other brain cancers, as well as for the treatment of neurodegenerative diseases is also carried out. Finally, a brief description of the advantages, the disadvantages, and the future perspectives in the use of these nanocarriers is reported, aiming at giving an insight of the limitations that have to be overcome in order to result in a delivery system with high therapeutic efficacy and without the limitations of the existing nano-systems.

Chemotherapeutic Drugs: DNA Damage and Repair in Glioblastoma

Despite improvements in therapeutic strategies, glioblastoma (GB) remains one of the most lethal cancers. The presence of the blood-brain barrier, the infiltrative nature of the tumor and several resistance mechanisms account for the failure of current treatments. Distinct DNA repair pathways can neutralize the cytotoxicity of chemo- and radio-therapeutic agents, driving resistance and tumor relapse. It seems that a subpopulation of stem-like cells, indicated as glioma stem cells (GSCs), is responsible for tumor initiation, maintenance and recurrence and they appear to be more resistant owing to their enhanced DNA repair capacity. Recently, attention has been focused on the pivotal role of the DNA damage response (DDR) in tumorigenesis and in the modulation of therapeutic treatment effects. In this review, we try to summarize the knowledge concerning the main molecular mechanisms involved in the removal of genotoxic lesions caused by alkylating agents, emphasizing the role of GSCs. Beside their increased DNA repair capacity in comparison with non-stem tumor cells, GSCs show a constitutive checkpoint expression that enables them to survive to treatments in a quiescent, non-proliferative state. The targeted inhibition of checkpoint/repair factors of DDR can contribute to eradicate the GSC population and can have a great potential therapeutic impact aiming at sensitizing malignant gliomas to treatments, improving the overall survival of patients.

Fibronectin-adherent peripheral blood derived mononuclear cells as Paclitaxel carriers for glioblastoma treatment: An in vitro study

BACKGROUND

Glioblastoma (GBM) represents the most aggressive malignant brain tumor in adults, with a risible median life expectancy despite gold standard treatment. Novel drug-delivery methods have been explored. Here we evaluated the possibility to use mononuclear cells (MCs) belonging to the monocytic-dendritic lineage as drug-carrier.

METHODS

MCs were obtained from 10 patients harboring a GBM, and from healthy volunteers, considered as controls. GBM tissue was also obtained from patients. MCs were cultured and the adherent population on fibronectin (FN-MCs), after immunocytochemistry and flow cytometry characterization, was loaded with Paclitaxel (FN-MCs-PTX). Antiproliferative and migration activity of FN-MCs-PTX was evaluated in two-dimensional (2D) and three-dimensional (3D) co-culture assays with red fluorescent U87 Malignant Glioma cells and primary GBM cells. Antiangiogenic properties of FN-MCs-PTX were tested on cultures with endothelial cells.

RESULTS

Phenotypical characterization showed a high expression of monocytic-dendritic markers in GBM cells and FN-MCs. FN-MCs demonstrated to effectively uptake PTX and to strongly inhibit GBM growth in vitro (P <0.01). Moreover, tumor-induced migration of MCs, although partially affected by the PTX cargo, remained statistically significant when compared with unprimed cells and this was confirmed in a 3D Matrigel model (P <0.01) and in a Trans-well assay (P <0.01). FN-MCs-PTX also disclosed considerable antiangiogenic properties.

DISCUSSION

Our results suggest that the fibronectin-adherent population of MCs isolated from peripheral blood can be an effective tool to inhibit GBM growth. Given the relative facility to obtain such cells and the short time needed for their culture and drug loading this approach may have potential as an adjuvant therapy for GBM.

Physicochemical characterization of chitosan-hyaluronan-coated solid lipid nanoparticles for the targeted delivery of paclitaxel: a proof-of-concept study in breast cancer cells

Aim: To investigate the potential of modified solid lipid nanoparticles (SLN) for the delivery of paclitaxel (PAX). Materials & methods: SLN loaded with PAX were prepared via modified high-pressure hot homogenization. Formulation parameters were optimized to obtain a high-quality delivery system. SLN cores were coated, layer-by-layer, with a chitosan and hyaluronan (HA) shell. Selectivity toward HA receptors was tested in a breast cancer cell line, MCF-7. Results: Stable and reproducible nano-sized and negatively charged nanoparticles resulted. Findings reveal that chitosan-HA-coated SLN facilitated the targeting, cellular uptake and the time-/dose-controlled delivery and release of PAX, enhancing intrinsic chemotherapeutic activities. Conclusion: SLN are suitable carrier candidates for nano-oncology given their localized, and potent cytotoxic potential overcoming multidrug-resistant cancer cells.

Solid lipid nanoparticles by coacervation loaded with a methotrexate prodrug: preliminary study for glioma treatment

AIM

Methotrexate-loaded biocompatible nanoparticles were tested for preliminary efficacy in glioma treatment.

MATERIALS & METHODS

Behenic acid nanoparticles, prepared by the coacervation method, were loaded with the ester prodrug didodecylmethotrexate, which was previously tested in vitro against glioblastoma human primary cultures. Nanoparticle conjugation with an ApoE mimicking chimera peptide was performed to obtain active targeting to the brain.

RESULTS & CONCLUSION

Biodistribution studies in healthy rats assessed the superiority of ApoE-conjugated formulation, which was tested on an F98/Fischer glioma model. Differences were observed in tumor growth rate (measured by MRI) between control and treated rats. In vitro tests on F98 cultured cells assessed their susceptibility to treatment, with consequent apoptosis, and allowed us to explain the apoptosis observed in glioma models.

CNS Targeted Nanoparticle Drug Delivery

The idea of formulating brain permeable nanoparticles stems from the need to treat various neurological disorders like Parkinson's disease, Alzheimer's disease, schizophrenia, depression and brain tumors. Neuropeptides, antibiotics, anticancer drugs and many CNS active drugs cannot cross blood brain barrier (BBB). Studies have revealed that when these drugs are loaded on to nanoparticles they not only cross BBB, but also exhibit decreased side effects. The drug can be dissolved, dispersed, encapsulated inside the nanoparticle or attached on to surface of nanoparticles. In 1995, dalargin was the first drug to be delivered across blood brain barrier (BBB) using polysorbate 80 coated nanoparticles. The size of nanoparticles is usually between 10-1000nm. For crossing BBB it should be less than 300 nm.

Preclinical safety of solid lipid nanoparticles and nanostructured lipid carriers: Current evidence from in vitro and in vivo evaluation

Solid lipid nanoparticles (SLN) and nanostructured lipid carriers (NLC) were designed as exceptionally safe colloidal carriers for the delivery of poorly soluble drugs. SLN/NLC have the particularity of being composed of excipientsalready approved for use in medicines for human use, which offers a great advantage over any other nanoparticulate system developed from novel materials. Despite this fact, any use of excipients in new route of administration or in new dosage form requires evidence of safety. After 25 years of research on SLN and NLC, enough evidence on their preclinical safety has been published. In the present work, published data on in vitro and in vivo compatibility of SLN/NLC have been surveyed, in order to provide evidence of high biocompatibility distinguished by intended administration route. We also identified critical factors and possible weak points in SLN/NLC formulations, such as the effect of surfactants on the cell viability in vitro, which should be considered for further development.

Conjugation of melanotransferrin antibody on solid lipid nanoparticles for mediating brain cancer malignancy

Solid lipid nanoparticles (SLNs) comprising complex internal lipids were conjugated with melanotransferrin antibody (MA) to carry anticancer etoposide across the blood-brain barrier (BBB) for managing glioblastoma multiforme (GBM). MA was crosslinked on the surface of etoposide-loaded SLNs (ETP-SLNs) to target human brain-microvascular endothelial cells (HBMECs) and U87MG cells. The experimental evidences showed that an increase in the tripalmitin weight percentage in lipids enhanced the particle size and viability of U87MG cells, however decreased the etoposide loading efficiency, MA conjugation efficiency, and permeability coefficient for etoposide across the BBB. A high level of MA on the particle surface increased the atomic ratio of nitrogen to phosphorus and permeability coefficient for propidium iodide and etoposide across the BBB, however reduced the MA conjugation efficiency, transendothelial electrical resistance, and viability of U87MG cells. Based on immunochemical staining, we found that MA on ETP-SLNs triggered the melanotransferrin-mediated transcytosis and promoted the growth-inhibitory efficacy to U87MG cells. MA-conjugated ETP-SLNs can be a promising colloidal delivery system for malignant GBM pharmacotherapy. © 2015 American Institute of Chemical Engineers Biotechnol. Prog., 32:480-490, 2016.

The DNA damage/repair cascade in glioblastoma cell lines after chemotherapeutic agent treatment

Therapeutic resistance in glioblastoma multiforme (GBM) has been linked to a subpopulation of cells with stem cell-like properties, the glioma stem cells (GSCs), responsible for cancer progression and recurrence. This study investigated the in vitro cytotoxicity of three chemotherapeutics, temozolomide (TMZ), doxorubicin (Dox) and paclitaxel (PTX) on glioma cell lines, by analyzing the molecular mechanisms leading to DNA repair and cell resistance, or to cell death. The drugs were tested on 16 GBM cell lines, grown as neurospheres (NS) or adherent cells (AC), by studying DNA damage occurrence by Comet assay, the expression by immunofluorescence and western blotting of checkpoint/repair molecules and apoptosis. The three drugs were able to provoke a genotoxic injury and to inhibit dose- and time-dependently cell proliferation, more evidently in AC than in NS. The first cell response to DNA damage was the activation of the damage sensors (p-ATM, p-53BP1, γ-H2AX), followed by repair effectors; the expression of checkpoint/repair molecules appeared higher in NS than in AC. The non-homologous repair pathway (NHEJ) seemed more involved than the homologous one (HR). Apoptosis occurred after long treatment times, but only a small percentage of cells in NS underwent death, even at high drug concentration, whereas most cells survived in a quiescent state and resumed proliferation after drug removal. In tumor specimens, checkpoint/repair proteins were constitutively expressed in GBMs, but not in low-grade gliomas.