Delivery of molecular and cellular medicine to solid tumors

Computational Modeling of Combination of Magnetic Hyperthermia and Temperature-Sensitive Liposome for Controlled Drug Release in Solid Tumor

Combination therapy, a treatment modality that combines two or more therapeutic methods, provides a novel pathway for cancer treatment, as it targets the region of interest (ROI) in a characteristically synergistic or additive manner. To date, liposomes are the only nano-drug delivery platforms that have been used in clinical trials. Here, we speculated that it could be promising to improve treatment efficacy and reduce side effects by intravenous administration of thermo-sensitive liposomes loaded with doxorubicin (TSL-Dox) during magnetic hyperthermia (MHT). A multi-scale computational model using the finite element method was developed to simulate both MHT and temperature-sensitive liposome (TSL) delivery to a solid tumor to obtain spatial drug concentration maps and temperature profiles. The results showed that the killing rate of MHT alone was about 15%, which increased to 50% using the suggested combination therapy. The results also revealed that this combination treatment increased the fraction of killed cells (FKCs) inside the tumor compared to conventional chemotherapy by 15% in addition to reducing side effects. Furthermore, the impacts of vessel wall pore size, the time interval between TSL delivery and MHT, and the initial dose of TSLs were also investigated. A considerable reduction in drug accumulation was observed in the tumor by decreasing the vessel wall pore size of the tumor. The results also revealed that the treatment procedure plays an essential role in the therapeutic potential of anti-cancer drugs. The results suggest that the administration of MHT can be beneficial in the TSL delivery system and that it can be employed as a guideline for upcoming preclinical studies.

Albumin-EDTA-Vanadium Is a Powerful Anti-Proliferative Agent, Following Entrance into Glioma Cells via Caveolae-Mediated Endocytosis

Human serum albumin (HSA) is efficiently taken up by cancer cells as a source of carbon and energy. In this study, we prepared a monomodified derivative of HSA covalently linked to an EDTA derivative and investigated its efficacy to shuttle weakly anti-proliferative EDTA associating ligands such as vanadium, into a cancer cell line. HSA-S-MAL-(CH₂)₂-NH-CO-EDTA was found to associate both with the vanadium anion (+5) and the vanadium cation (+4) with more than thrice the associating affinity of those ligands toward EDTA. Both conjugates internalized into glioma tumor cell line via caveolae-mediated endocytosis pathway and showed potent anti-proliferative capacities. IC₅₀ values were in the range of 0.2 to 0.3 µM, potentiating the anti-proliferative efficacies of vanadium (+4) and vanadium (+5) twenty to thirty fold, respectively. HSA-EDTA-VO⁺⁺ in particular is a cancer permeable prodrug conjugate. The associated vanadium (+4) is not released, nor is it active anti-proliferatively prior to its engagement with the cancerous cells. The bound vanadium (+4) dissociates from the conjugate under acidic conditions with half maximal value at pH 5.8. In conclusion, the anti-proliferative activity feature of vanadium can be amplified and directed toward a cancer cell line. This is accomplished using a specially designed HSA-EDTA-shuttling vehicle, enabling vanadium to be anti-proliferatively active at the low micromolar range of concentration.

Does Pharmacodynamics of Drugs Change After Presenting them as Nanoparticles Like their Pharmacokinetics?

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Nowadays, the breakthrough in different medical branches makes it feasible to designate new methods of drug delivery to achieve the most cost-effective and the least unpleasant consequenceimposing solutions to overcome a wide range of diseases.

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Nanoparticle (NP) drugs entered the therapeutic system, especially in cancer chemotherapy. These drugs are quite well-known for two traits of being long-acting and less toxic. For a long time, it has been investigated how NPs will change the kinetics of drugs. However, there are a few studies that inclined their attention to how NPs affect the dynamics of drugs. In this review, the latter point will mainly be discussed in an example-based manner. Besides, other particular features of NPs will be briefly noted.

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NPs are capable of affecting the biologic system as much as a drug. Moreover, NPs could arise a wide variety of effects by triggering their own receptors. NPs are able to change a receptor function and manipulate its downstream signaling cascade.

A drug delivery perspective on intratumoral-immunotherapy in renal cell carcinoma

In less than 5years immune checkpoint inhibitors (ICI) went from first FDA approval to become first-line options in advanced renal cell carcinoma. Despite that many patients have benefited from ICI, a significant fraction of individuals are refractory to these new immunological treatments. In this review, we discussed using intratumoral (i.t.) route of drug administration as an alternative to systemic therapy to increase the response rates and to circumvent potential drug-induced systemic adverse events. We provided a historic account of i.t. drug treatments in cancer and reviewed the contemporary experience in local drug delivery. We discussed the potential for enhancing the therapeutic impact of ICI by leveraging hydrogels as drug delivery vehicles and presented an outlook for implementing i.t. in renal cell carcinoma.

Hypoxia-responsive block copolymer radiosensitizers as anticancer drug nanocarriers for enhanced chemoradiotherapy of bulky solid tumors

Radiosensitizers play an important role in the clinical radiotherapy of hypoxic solid tumors to improve therapeutic efficacy. However, the in vivo performance of clinically used small-molecule radiosensitizers is commonly compromised by low bioavailability in hypoxic tumor regions. Herein, amphiphilic block copolymer radiosensitizers are prepared from clinically approved poly(ethylene glycol)-block-poly(l-glutamic acid) (PEG-b-PLG) and metronidazole (MN) to obtain MN-grafted PEG-b-PLG (PEG-b-P(LG-g-MN)) via condensation reaction, which can self-assemble into core-shell micelles as nanoparticle-formulated radiosensitizers in aqueous solution. The radiosensitizers are demonstrated to possess significantly higher sensitization enhancement ratio (SER) of 2.18 and potent in vivo tumor ablation capability upon exposure to electron beam irradiation compared with clinically used sodium glycididazole (GS) with SER of 1.32. Moreover, after optimizing the ratios of carboxyl and MN groups, PEG-b-P(LG-g-MN) micelles can be used to encapsulate doxorubicin (DOX@HMs) efficiently. Hypoxia-responsive structural transformation of MN into hydrophilic aminoimidazole triggers fast DOX release from DOX@HMs. After intravenous injection of DOX@HMs, potent ablation capability against bulky solid tumors (∼500 mm³) is realized at a low radiation dose (4 Gy) via enhanced chemoradiotherapy. Therefore, the developed novel amphiphilic block copolymer radiosensitizers can be concurrently used as high-efficiency radiosensitizers and hypoxia-responsive DOX nanocarriers for enhanced chemoradiotherapy.

An analytical poroelastic model of a non-homogeneous medium under creep compression for ultrasound poroelastography applications - Part II

An analytical theory for the unconfined creep behavior of a cylindrical inclusion (simulating a soft tissue tumor) embedded in a cylindrical background sample (simulating normal tissue) is presented and analyzed in this paper. Both the inclusion and the background are considered as fluid-filled, porous materials, each of them being characterized by a set of mechanical parameters. Specifically, in this derivation, the inclusion is assumed to have significantly higher interstitial permeability than the background. The formulations of the effective Poisson's ratio (EPR) and fluid pressure in the inclusion and in the background are derived for the case of a sample subjected to a creep compression. The developed analytical expressions are validated using finite element models (FEM). Statistical comparison between the results obtained from the developed model and the results from FEM demonstrates accuracy of the proposed theoretical model higher than 99.4%. The model presented in this paper complements the one reported in the companion paper (Part I), which refers to the case of an inclusion having less interstitial permeability than the background.

An analytical poroelastic model of a non-homogeneous medium under creep compression for ultrasound poroelastography applications - Part I

An analytical theory for the unconfined creep behavior of a cylindrical inclusion (simulating a soft tissue tumor) embedded in a cylindrical background sample (simulating normal tissue) is presented and analyzed in this paper. Both the inclusion and the background are considered as fluid-filled, porous materials, each of them being characterized by a set of mechanical properties. Specifically, in this paper, the inclusion is considered to be less permeable than the background. The cylindrical sample is compressed using a constant pressure within two frictionless plates and is allowed to expand in an unconfined way along the radial direction. Analytical expressions for the effective Poisson's ratio (EPR) and fluid pressure inside and outside the inclusion are derived and analyzed. The theoretical results are validated using finite element models (FEM). Statistical analysis shows excellent agreement between the results obtained from the developed model and the results from FEM. Thus the developed theoretical model can be used in medical imaging modalities such as ultrasound poroelastography to extract the mechanical parameters of tissues and/or to better understand the impact of the different mechanical parameters on the estimated displacements, strains, stresses and fluid pressure inside a tumor and in the surrounding tissue.

Oxygen-independent combined photothermal/photodynamic therapy delivered by tumor acidity-responsive polymeric micelles

Tumor hypoxia strikingly restricts photodynamic therapy (PDT) efficacy and limits its clinical applications in cancer therapy. The ideal strategy to address this issue is to develop oxygen-independent PDT systems. Herein, the rationally designed tumor pH-responsive polymeric micelles are devised to realize oxygen-independent combined PDT and photothermal therapy (PTT) under near-infrared light (NIR) irradiation. The triblock copolymer, poly(ethylene glycol)-b-poly(ε-caprolactone)-b-poly(2-(piperidin-1-yl)ethyl methacrylate) (PEG-b-PCL-b- PPEMA), was prepared to co-encapsulate cypate and singlet oxygen donor (diphenylanthracene endoperoxide, DPAE) via self-assembly to obtain the micellar delivery system (C/O@N-Micelle). C/O@N-Micelle showed remarkable tumor accumulation and improved cellular internalization (2.1 times) as the pH value was changed from 7.4 during blood circulation to 6.8 in tumor tissues. The micelles could produce a potent hyperthermia for PTT of cypate under 808 nm NIR irradiation, which simultaneously induced thermal cycloreversion of DPAE generating abundant singlet oxygen for PDT without participation of tumor oxygen. Finally, the photothermally triggered PDT and PTT combination achieved efficient tumor ablation without remarkable systemic toxicity in an oxygen-independent manner. This work represents an efficient strategy for oxygen-independent combined PDT and PTT of cancers under NIR irradiation through co-encapsulation of cypate and DPAE into tumor pH-responsive polymeric micelles.

Nanoparticles and Controlled Delivery for Bioactive Compounds: Outlining Challenges for New "Smart-Foods" for Health

Nanotechnology is a field of research that has been stressed as a very valuable approach for the prevention and treatment of different human health disorders. This has been stressed as a delivery system for the therapeutic fight against an array of pathophysiological situations. Actually, industry has applied this technology in the search for new oral delivery alternatives obtained upon the modification of the solubility properties of bioactive compounds. Significant works have been made in the last years for testing the input that nanomaterials and nanoparticles provide for an array of pathophysiological situations. In this frame, this review addresses general questions concerning the extent to which nanoparticles offer alternatives that improve therapeutic value, while avoid toxicity, by releasing bioactive compounds specifically to target tissues affected by specific chemical and pathophysiological settings. In this regard, to date, the contribution of nanoparticles to protect encapsulated bioactive compounds from degradation as a result of gastrointestinal digestion and cellular metabolism, to enable their release in a controlled manner, enhancing biodistribution of bioactive compounds, and to allow them to target those tissues affected by biological disturbances has been demonstrated.

In Vitro Evaluation of Vegf-Pseudomonas Exotoxin: A Conjugated on Tumor Cells

Background:

Angiogenesis which occurs mandatory in solid tumors, is a critical step in malignancy progression. Vascular endothelial growth factor (VEGF) is mainly responsible for angiogenesis process and facilitates the formation of new vessels. Distribution of monoclonal antibodies against VEGF or VEGF receptor (VEGFR) into the solid tumors is limited because of their huge dimensions. Moreover, many investigations have demonstrated the usefulness of immunotoxins to halt angiogenesis in solid tumors.

Materials and Methods:

We designed, expressed and evaluated the cytotoxicity of a novel nano-immunotoxin composed of VEGF splice variant containing 121 amino acids (VEGF121) and truncated the exotoxin A of Pseudomonas aeruginosa (PE38-KDEL). The fusion protein VEGF121-PE38 was successfully cloned and expressed in Escherichia coli, purified by Ni^{+ 2} affinity chromatography. The fusion protein was subsequently subjected to refolding using the reduced and oxidized glutathione.

Results:

The expression level of the fusion protein reached to 1 mg/ml. The VEGF121-PE38 immunotoxin showed a 59 KDa MW which had cytotoxic effect on HUVEC and 293/KDR cells as low and high expressing VEGFR2 cells, respectively. But the cytotoxicity on 293/KDR was 100 folds more than that of VEGFR2 low expressing cell HUVEC.

Conclusion:

The designed immunotoxin showed more selectivity for higher VEGFR2 expressing cells in vitro.

N-Butyl-2-cyanoacrylate-based injectable and in situ-forming implants for efficient intratumoral chemotherapy

The local delivery of chemotherapeutic drugs to tumor sites is an effective approach for achieving therapeutic drug concentrations in solid tumors. Injectable implants with the ability to form in situ represent one of the most promising technologies for intratumoral chemotherapy. However, many issues must be resolved before these implants can be applied in clinical practice. Herein, we report a novel injectable in situ-forming implant system composed of n-butyl-2-cyanoacrylate (NBCA) and ethyl oleate, and the sol–gel phase transition is activated by anions in body fluids or blood. This newly developed injectable NBCA ethyl oleate implant (INEI) is biodegradable, biocompatible, and non-toxic. INEI solidifies in several seconds after exposure to body fluids or blood, and the implant’s in vivo degradation time can be controlled. In addition, the pore sizes formed by the polymerization of NBCA can be decreased by increasing the NBCA concentration in the implants. Therefore, the drug retention/release time can be adjusted from a few weeks to several months by changing the concentration of NBCA in the implant formulation. Anti-tumor experiments in animal models showed that the average growth inhibition rate of xenografted human breast cancer cells by the paclitaxel-loaded INEI (40% NBCA) was 80%, and they also indicated that tumors in some of the mice were completely eliminated by just a single dosage injection. For the epirubicin-loaded INEI (50% NBCA), the average growth inhibition rate of xenografted human liver cancer cells was 58%. Thus, the chemotherapeutic drug-loaded INEIs exhibited excellent therapeutic efficacy for local chemotherapy.

Emerging strategies for delivering antiangiogenic therapies to primary and metastatic brain tumors

Five-year survival rates have not increased appreciably for patients with primary and metastatic brain tumors. Nearly 17,000 patients die from primary brain tumors, whereas approximately 200,000 cases are diagnosed with brain metastasis every year in the US alone. At the same time, with improved control of systemic disease, the incidence of brain metastasis is increasing. Thus, novel approaches for improving the treatment outcome for these uniformly fatal diseases are needed urgently. In the review, we summarize the challenges in the treatment of these diseases using antiangiogenic therapies alone or in combination with radio-, chemo- and immuno-therapies. We also discuss the emerging strategies to improve the treatment outcome using both pharmacological approaches to normalize the tumor microenvironment and physical approaches (e.g., focused ultrasound) to modulate the blood-tumor-barrier, along with limitations of each approach. Finally, we offer some new avenues of future research.

Development of self-forming doxorubicin-loaded polymeric depots as an injectable drug delivery system for liver cancer chemotherapy

The objective of this work was to develop self-forming doxorubicin-loaded polymeric depots as an injectable drug delivery system for liver cancer chemotherapy and studied the release profiles of doxorubicin (Dox) from different depot formulations. Tri-block copolymers of poly(ε-caprolactone), poly(D,L-lactide) and poly(ethylene glycol) named PLECs were successfully used as a biodegradable material to encapsulate Dox as the injectable local drug delivery system. Depot formation and encapsulation efficiency of these depots were evaluated. Results show that depots could be formed and encapsulate Dox with high drug loading content. For the release study, drug loading content (10, 15 and 20% w/w) and polymer concentration (25, 30, and 35% w/v) were varied. It could be observed that the burst release occurred within 1-2 days and this burst release could be reduced by physical mixing of hydroxypropyl-beta-cyclodextrin (HP-β-CD) into the depot system. The degradation at the surface and cross-section of the depots were examined by Scanning Electron Microscope (SEM). In addition, cytotoxicity of Dox-loaded depots and blank depots were tested against human liver cancer cell lines (HepG2). Dox released from depots significantly exhibited potent cytotoxic effect against HepG2 cell line compared to that of blank depots. Results from this study reveals an important insight in the development of injectable drug delivery system for liver cancer chemotherapy. Schematic diagram of self-forming doxorubicin-loaded polymeric depots as an injectable drug delivery system and in vitro characterizations. (a) Dox-loaded PLEC depots could be formed with more than 90% of sustained-release Dox at 25% polymer concentration and 20% Dox-loading content. The burst release occurred within 1-2 days and could be reduced by physical mixing of hydroxypropyl-beta-cyclodextrin (HP-β-CD) into the depot system. (b) Dox released from depots significantly exhibited potent cytotoxic effect against human liver cancer cell lines (HepG2 cell line) compared to that of blank depots.

Facile Preparation and Radiotherapy Application of an Amphiphilic Block Copolymer Radiosensitizer

Radiosensitizer plays an important role in the cancer radiotherapy for efficient killing of hypoxic cancer cells at a low radiation dose. However, the commercially available small molecular radiosensitizers show low efficiency due to poor bioavailability in tumor tissues. In this report, we develop a novel amphiphilic block copolymer radiosensitizer, metronidazole-conjugated poly(ethylene glycol)-b-poly(γ-propargyl-l-glutamate) (PEG-b-P(PLG-g-MN)), which can be self-assembled into core-shell micelles (MN-Micelle) with an optimal size of ∼60 nm in aqueous solution. In vitro cytotoxicity evaluation indicated that MN-Micelle sensitized the hypoxic cancer cells more efficiently under radiation with the sensitization enhancement ratio (SER) of 1.62 as compared with that of commercially available sodium glycididazole (GS; SER = 1.17) at the metronidazole-equivalent concentration of 180 μg/mL. Upon intravenous injection of MN-Micelle into the tumor-bearing mice, high tumor deposition was achieved, which finally suppressed tumor growth completely after electron beam radiation at a low radiation dose of 4 Gy. MN-Micelle with outstanding performance as an in vivo radiosensitizer holds great potentials for translation into radiotherapy application.

Energy-triggered drug release from polymer nanoparticles for orthopedic applications

Sequestra, present in many cancers and orthopedic infections, provide a safe harbor for the development of drug resistance. In the face of burgeoning drug resistance, the importance of nanoscale, microenvironment-triggered drug delivery cannot be overestimated. Such strategies may preserve pharmaceutical efficacy and significantly alter the etiology of many orthopedic diseases. Although temperature-, pH- and redox-responsive nanoparticle-based systems have been extensively studied, local drug delivery from polymeric nanoparticles can be triggered by a variety of energy forms. This review offers an overview of the state of the field as well as a perspective on the safety and efficacy of ultrasound, hyperthermia and radio frequency-triggered internal delivery systems in a variety of applications.

Paclitaxel-loaded polymeric depots as injectable drug delivery system for cancer chemotherapy of hepatocellular carcinoma

In this work, paclitaxel-encapsulated polymeric depots were prepared and characterized as drug delivery system for cancer chemotherapy against hepatocellular carcinoma. Effects of different parameters, including drug-loading content, polymer concentration and depot weight on depot formation, percentage of sustained-release taxol and drug release profile were evaluated. Paclitaxel-loaded depots were successfully formed at the polymer concentration above 25% w/v. For all formulations, paclitaxel could be encapsulated with very high percentage of sustained-release taxol (>90%). The release rate of paclitaxel from depots could be controlled by the amount of drug-loading content, polymer concentration and depot weight. Cytotoxicity against liver cancer cell line, HepG2, was evaluated by medium extraction method. Paclitaxel releasing from depots showed cytotoxic effect against HepG2 at different incubation times, whereas blank depots exhibited no cytotoxicity.

Sonoporation: Applications for Cancer Therapy

Therapeutic efficacy of both traditional chemotherapy and gene therapy in cancer is highly dependent on the ability to deliver drugs across natural barriers, such as the vessel wall or tumor cell membranes. In this regard, sonoporation induced by ultrasound-guided microbubble (USMB) destruction has been widely investigated in the enhancement of therapeutic drug delivery given it can help overcome these natural barriers, thereby increasing drug delivery into cancer. In this chapter we discuss challenges in current cancer therapy and how some of these challenges could be overcome using USMB-mediated drug delivery. We particularly focus on recent advances in delivery approaches that have been developed to further improve therapeutic efficiency and specificity of various cancer treatments. An example of clinical translation of USMB-mediated drug delivery is also shown.

Size-Dependent Gold Nanoparticle Interaction at Nano-Micro Interface Using Both Monolayer and Multilayer (Tissue-Like) Cell Models

Gold nanoparticles (GNPs) are emerging as a novel tool to improve existing cancer therapeutics. GNPs are being used as radiation dose enhancers in radiation therapy as well as anticancer drugs carriers in chemotherapy. However, the success of GNP-based therapeutics depends on their ability to penetrate tumor tissue. GNPs of 20 and 50 nm diameters were used to elucidate the effects of size on the GNP interaction with tumor cells at monolayer and multilayer level. At monolayer cell level, smaller NPs had a lower uptake compared to larger NPs at monolayer cell level. However, the order was reversed at tissue-like multilayer level. The smaller NPs penetrated better compared to larger NPs in tissue-like materials. Based on our study using tissue-like materials, we can predict that the smaller NPs are better for future therapeutics due to their greater penetration in tumor tissue once leaving the leaky blood vessels. In this study, tissue-like multilayer cellular structures (MLCs) were grown to model the post-vascular tumor environment. The MLCs exhibited a much more extensive extracellular matrix than monolayer cell cultures. The MLC model can be used to optimize the nano-micro interface at tissue level before moving into animal models. This would accelerate the use of NPs in future cancer therapeutics.

Overview of Methods for Overcoming Hindrance to Drug Delivery to Tumors, with Special Attention to Tumor Interstitial Fluid

Every drug used to treat cancer (chemotherapeutics, immunological, monoclonal antibodies, nanoparticles, radionuclides) must reach the targeted cells through the tumor environment at adequate concentrations, in order to exert their cell-killing effects. For any of these agents to reach the goal cells, they must overcome a number of impediments created by the tumor microenvironment (TME), beginning with tumor interstitial fluid pressure (TIFP), and a multifactorial increase in composition of the extracellular matrix (ECM). A primary modifier of TME is hypoxia, which increases the production of growth factors, such as vascular endothelial growth factor and platelet-derived growth factor. These growth factors released by both tumor cells and bone marrow recruited myeloid cells form abnormal vasculature characterized by vessels that are tortuous and more permeable. Increased leakiness combined with increased inflammatory byproducts accumulates fluid within the tumor mass (tumor interstitial fluid), ultimately creating an increased pressure (TIFP). Fibroblasts are also up-regulated by the TME, and deposit fibers that further augment the density of the ECM, thus, further worsening the TIFP. Increased TIFP with the ECM are the major obstacles to adequate drug delivery. By decreasing TIFP and ECM density, we can expect an associated rise in drug concentration within the tumor itself. In this overview, we will describe all the methods (drugs, nutraceuticals, and physical methods of treatment) able to lower TIFP and to modify ECM used for increasing drug concentration within the tumor tissue.

Folate-decorated anticancer drug and magnetic nanoparticles encapsulated polymeric carrier for liver cancer therapeutics

Nanoparticulate system with theranostic applications has attracted significant attention in cancer therapeutics. In the present study, we have developed a novel composite PLGA NP co-encapsulated with anticancer drug (sorafenib) and magnetic NP (SPION). We have successfully developed nanosized folate-conjugated PEGylated PLGA nanoparticles (SRF/FA-PEG-PLGA NP) with both anticancer and magnetic resonance property. We have showed that FA-conjugated NP exhibits sustained drug release and enhanced cellular uptake in BEL7402 cancer cells. The targeted NP effectively suppressed the tumor cell proliferation and has improved the anticancer efficacy than that of free drug or non-targeted one. Additionally, enhanced MRI properties demonstrate this formulation has good imaging agent characteristics. Finally, SRF/FA-PEG-PLGA NP effectively inhibited the colony forming ability indicating its superior anticancer effect. Together, these multifunctional nanoparticles would be most ideal to improve the therapeutic response in cancer and holds great potential to be a part of future nanomedicine. Our unique approach could be extended for multiple biomedical applications.

Ultrasound-mediated destruction of paclitaxel and oxygen loaded lipid microbubbles for combination therapy in ovarian cancer xenografts

We have synthesized multifunctional oxygen and paclitaxel loaded microbubbles (OPLMBs) for ultrasound mediated delivery of combination therapy in an ovarian cancer xenograft model. In comparison with other therapeutic options, intravenous injection of OPLMBs followed by ultrasound mediation yielded a superior therapeutic outcome. Immunohistochemical analyses of the dissected tumor tissue confirmed the increased tumor apoptosis and the reduced VEGF expression after treatment. Western Blot tests further confirmed the decreased expressions of HIF-1α and P-gp. Our experiment suggests that ultrasound mediation of OPLMBs may provide a promising drug delivery strategy for the combination treatment of ovarian cancer.

Enhanced therapeutic efficacy and cytotoxicity of doxorubicin-loaded vitamin E – Pluronic micelles against liver cancer

In this study, a new polymeric micelle delivery system was developed to increase the therapeutic efficacy of doxorubicin (DOX) and to reduce its associated side effects.

Brachytherapy application with in situ dose painting administered by gold nanoparticle eluters

PURPOSE

Recent studies show promise that administering gold nanoparticles (GNP) to tumor cells during brachytherapy could significantly enhance radiation damage to the tumor. A new strategy proposed for sustained administration of the GNP in prostate tumors is to load them into routinely used brachytherapy spacers for customizable in situ release after implantation. This in silico study investigated the intratumor biodistribution and corresponding dose enhancement over time due to GNP released from such GNP-loaded brachytherapy spacers (GBS).

METHOD AND MATERIALS

An experimentally determined intratumoral diffusion coefficient (D) for 10-nm nanoparticles was used to estimate D for other sizes by using the Stokes-Einstein equation. GNP concentration profiles, obtained using D, were then used to calculate the corresponding dose enhancement factor (DEF) for each tumor voxel, using dose painting-by-numbers approach, for times relevant to the considered brachytherapy sources' lifetimes. The investigation was carried out as a function of GNP size for the clinically applicable low-dose-rate brachytherapy sources iodine-125 (I-125), palladium-103 (Pd-103), and cesium-131 (Cs-131).

RESULTS

Results showed that dose enhancement to tumor voxels and subvolumes during brachytherapy can be customized by varying the size of GNP released or eluted from the GBS. For example, using a concentration of 7 mg/g GNP, significant DEF (>20%) could be achieved 5 mm from a GBS after 5, 12, 25, 46, 72, 120, and 195 days, respectively, for GNP sizes of 2, 5, 10, 20, 30, and 50 nm and for 80 nm when treating with I-125.

CONCLUSIONS

Analyses showed that using Cs-131 provides the highest dose enhancement to tumor voxels. However, given its relatively longer half-life, I-125 presents the most flexibility for customizing the dose enhancement as a function of GNP size. These findings provide a useful reference for further work toward development of potential new brachytherapy application with in situ dose painting administered via gold nanoparticle eluters for prostate cancer.

Therapeutic efficacy and toxicity of tamoxifen loaded PLA nanoparticles for breast cancer

This study was carried out to assess the therapeutic efficacy and toxicity of tamoxifen (Tmx) loaded poly(d,l-lactic acid) (PLA) nanoparticles (Tmx-NPs) for breast cancer. An in vivo study was conducted to determine the effect of Tmx-NPs on DMBA induced mammary tumor in female Wistar rat. The experimental results showed that the mean diameter of Tmx-NPs was 224 ± 3 nm with 68 ± 2% (w/w) of entrapment efficiency. In in vivo study, the tumor size in rat was significantly reduced (P < 0.001) by treating Tmx-NPs as compared to pure Tmx and untreated group (control DMBA). Tmx-NPs showed the marked reduction in hepatotoxicity and renal toxicity when compared to pure Tmx as evidenced by histopathological examination of liver and kidney tissues as well as estimation of AST, ALT levels, and creatinine, urea, blood urea nitrogen levels. Oxidative stress and lipid peroxidation was estimated in spleen, liver and kidney and was found significantly high in pure Tmx treated group as compared to Tmx-NPs and control group. Immunological parameters like blastogenic response of splenocytes, TLC, DLC were studied and found significantly high in pure Tmx treated group but the variations were nonsignificant in Tmx-NPs group as compared to control. Thus, Tmx-NPs have significant therapeutic efficacy with reduced side effects.

Photoswitchable nanoparticles for in vivo cancer chemotherapy

There are many obstacles to effective cancer chemotherapy, including drug penetration and accumulation in tumors and drug systemic toxicity. The penetration of therapies into tumors is limited by the dense tumor matrix and by compression of the tumor vasculature. We have developed spiropyran-based nanoparticles that shrink from 103 to 49 nm upon irradiation at 365 nm. That shrinkage enhanced tissue penetration and drug release. Irradiation of s.c. HT-1080 tumors in nude mice administered i.v. docetaxel-containing nanoparticles was more effective treatment than free docetaxel or encapsulated docetaxel without irradiation. Irradiation at the tumor site also resulted in less systemic toxicity than if the nanoparticles were irradiated before injection, presumably because of less systemically distributed free drug. The enhanced efficacy of nanoparticles in irradiated tumors may have been related to the observed enhanced tumor penetration by nanoparticles and decompression of tumor blood vessels, which may also increase nanoparticle delivery into tumors.

The Synthesis of Methylene Blue Photosensitiser Conjugated with Gold Nanoparticles

Nowadays, nanocarriers possess growing interest for medical usage such as photodynamic therapy. Conjunction of these nanoparticles with photosensitising drugs leads to more cellular uptake, higher photocytotoxicty, higher biocompatibility and more selectivity. Previous papers conclude that the 50 nm size nanoparticles give the highest cellular uptake for the purpose of photodynamic therapy. In this paper the gold nanoparticles were synthesized based on TurkevichFrens method. Moreover, methylene blue as a relevant photosensitiser was conjugated to achieved AuNPs. The spectrometric results of UV-visible and Fourier Transform Infrared spectroscopy (FTIR) as well as Atomic Force Microscopy (AFM) emphasis on the presence of MB sensitizers connected to resulting 50 nm gold nanoparticles.

Bioavailability of phytochemicals and its enhancement by drug delivery systems

Issues of poor oral bioavailability of cancer chemopreventives have hindered progress in cancer prevention. Novel delivery systems that modulate the pharmacokinetics of existing drugs, such as nanoparticles, cyclodextrins, niosomes, liposomes and implants, could be used to enhance the delivery of chemopreventive agents to target sites. The development of new approaches in prevention and treatment of cancer could encompass new delivery systems for approved and newly investigated compounds. In this review, we discuss some of the delivery approaches that have already made an impact by either delivering a drug to target tissue or increasing its bioavailability by many fold.

The 'nanobig rod' class of gold nanorods: optimized dimensions for improved in vivo therapeutic and imaging efficacy

Currently, gold nanorods can be synthesized in a wide range of sizes. However, for the intended biological applications gold nanorods with approximate dimensions 50 nm × 15 nm are used. We investigate by computer simulation the effect of particle dimensions on the optical and thermal properties in the context of the specific applications of photoacoustic imaging. In addition we discuss the influence of particle size in overcoming the following biophysical barriers when administrated in vivo: extravasation, avoidance of uptake by organs of the reticuloendothelial system, penetration through the interstitium, binding capability and uptake by the target cells. Although more complex biological influences can be introduced in future analysis, the present work illustrates that larger gold nanorods, designated by us as 'nanobig rods', may perform better at meeting the requirements for successful in vivo applications compared to their smaller counterparts, which are conventionally used.

An efficient bioorthogonal strategy using CuAAC click chemistry for radiofluorinations of SNEW peptides and the role of copper depletion

The EphB2 receptor is known to be overexpressed in various types of cancer and is therefore a promising target for tumor cell imaging by positron emission tomography (PET). In this regard, imaging could facilitate the early detection of EphB2-overexpressing tumors, monitoring responses to therapy directed toward EphB2, and thus improvement in patient outcomes. We report the synthesis and evaluation of several fluorine-18-labeled peptides containing the SNEW amino acid motif, with high affinity for the EphB2 receptor, for their potential as radiotracers in the non-invasive imaging of cancer using PET. For the purposes of radiofluorination, EphB2-antagonistic SNEW peptides were varied at the C terminus by the introduction of L-cysteine, and further by alkyne- or azide-modified amino acids. In addition, two novel bifunctional and bioorthogonal labeling building blocks [(18)F]AFP and [(18)F]BFP were applied, and their capacity to introduce fluorine-18 was compared with that of the established building block [(18)F]FBAM. Copper-assisted Huisgen 1,3-dipolar cycloaddition, which belongs to the set of bioorthogonal click chemistry reactions, was used to introduce both novel building blocks into azide- or alkyne-modified SNEW peptides under mild conditions. Finally, the depletion of copper immediately after radiolabeling is a highly important step of this novel methodology.

Coupled finite difference and boundary element methods for fluid flow through a vessel with multibranches in tumours

A mathematical model and a numerical solution procedure are developed to simulate flow field through a 3D permeable vessel with multibranches embedded in a solid tumour. The model is based on Poisseuille's law for the description of the flow through the vessels, Darcy's law for the fluid field inside the tumour interstitium, and Starling's law for the flux transmitted across the vascular walls. The solution procedure is based on a coupled method, in which the finite difference method is used for the flow in the vessels and the boundary element method is used for the flow in the tumour. When vessels meet each other at a junction, the pressure continuity and mass conservation are imposed at the junction. Three typical representative structures within the tumour vasculature, symmetrical dichotomous branching, asymmetrical bifurcation with uneven radius of daughter vessels and trifurcation, are investigated in detail as case studies. These results have demonstrated the features of tumour flow environment by the pressure distributions and flow velocity field.

Matrigel alters the pathophysiology of orthotopic human breast adenocarcinoma xenografts with implications for nanomedicine evaluation

Matrigel, a mouse sarcoma-derived basement membrane protein mixture, is frequently used to facilitate human tumor xenograft growth in rodents. Despite its known effects on tumor growth and metastasis, its impact on tumor pathophysiology and preclinical evaluation of nanomedicines in tumor xenografts has not been reported previously. Herein bilateral MDA435 tumors were established orthotopically with (Mat+) or without (Mat-) co-injection of Matrigel. Tumor perfusion, morphology and nanoparticle retention were evaluated. As compared to Mat- tumors, Mat+tumors exhibited enhanced vascular perfusion and lymphatic flow, greater blood vessel and lymphatic growth within the tumor core, and more deformation and collapse of lymphatics in tumor-associated lymph nodes. These changes were accompanied by reduced nanoparticle retention in Mat+tumors. The results suggest that Matrigel is not a passive medium for tumor growth, but rather significantly alters long-term tumor architecture. These findings have significant implications for the evaluation of therapeutic nanomedicine in xenograft mouse models.

FROM THE CLINICAL EDITOR

Matrigel is utilized in facilitating human tumor xenograft growth in rodents. The authors demonstrate that Matrigel is not a passive medium for tumor growth; instead it significantly alters long-term tumor architecture, with major implications in the evaluation of therapeutic nanomedicine in xenograft mouse models.

Effect of wall compliance and permeability on blood-flow rate in counter-current microvessels formed from anastomosis during tumor-induced angiogenesis

Tumor blood-flow is inhomogeneous because of heterogeneity in tumor vasculature, vessel-wall leakiness, and compliance. Experimental studies have shown that normalization of tumor vasculature by antiangiogenic therapy can improve tumor microcirculation and enhance the delivery of therapeutic agents to tumors. To elucidate the quantitative relationship between the vessel-wall compliance and permeability and the blood-flow rate in the microvessels of the tumor tissue, the tumor tissue with the normalized vasculature, and the normal tissue, we developed a transport model to simultaneously predict the interstitial fluid pressure (IFP), interstitial fluid velocity (IFV) and the blood-flow rate in a counter-current microvessel loop, which occurs from anastomosis in tumor-induced angiogenesis during tumor growth. Our model predicts that although the vessel-wall leakiness greatly affects the IFP and IFV, it has a negligible effect on the intravascular driving force (pressure gradient) for both rigid and compliant vessels, and thus a negligible effect on the blood-flow rate if the vessel wall is rigid. In contrast, the wall compliance contributes moderately to the IFP and IFV, but significantly to the vessel radius and to the blood-flow rate. However, the combined effects of vessel leakiness and compliance can increase IFP, which leads to a partial collapse in the blood vessels and an increase in the flow resistance. Furthermore, our model predictions speculate a new approach for enhancing drug delivery to tumor by modulating the vessel-wall compliance in addition to reducing the vessel-wall leakiness and normalizing the vessel density.

A review of current nanoparticle and targeting moieties for the delivery of cancer therapeutics

The tumor microenvironment provides unique challenges for the delivery of chemotherapeutic agents in doses that are effective while ensuring minimal systemic toxicity. The primary limitation of current therapeutics is a lack of specificity in delivery, as they target healthy and cancerous cells alike. The development of nanoscale carriers capable of delivering cancer therapies has the potential to overcome both systemic and tumor barriers and provide specific, targeted delivery. This review seeks to provide an overview of available nanoscale drug carriers by exploring the wide variety of developed nanostructures and the most commonly used moieties for targeted delivery. Additionally, the use of nanoscale carriers will be motivated by examining tumor physiology and the specific barriers present within both the tumor microenvironment and systemic delivery.

Biological rationale for the design of polymeric anti-cancer nanomedicines

Understanding the biological features of cancer is the basis for designing efficient anti-cancer nanomedicines. On one hand, important therapeutic targets for anti-cancer nanomedicines need to be identified based on cancer biology, to address the unmet medical needs. On the other hand, the unique pathophysiological properties of cancer affect the delivery and interactions of anti-cancer nanomedicines with their therapeutic targets. This review discusses several critical cancer biological properties that challenge the currently available anti-cancer treatments, including cancer heterogeneity and cancer stem cells, the complexcity of tumor microenvironment, and the inevitable cancer metastases. In addition, the biological bases of the enhanced permeability and retention (EPR) effect and tumor-specific active targeting, as well as the physiological barriers for passive and active targeting of anti-cancer nanomedicines are covered in this review. Correspondingly, possible nanomedicine strategies to target cancer heterogeneity, cancer stem cells and metastases, to overcome the challenges related to tumor passive targeting and tumor penetration, and to improve the interactions of therapeutic payloads with the therapeutic targets are discussed. The focus is mainly on the designs of polymeric anti-cancer nanomedicines.

Tumor cells-specific targeting delivery achieved by A54 peptide functionalized polymeric micelles

The delivery of all of administrated chemotherapeutics into tumor cells is an extreme object for tumor targeting therapy to enhance the curative effect and eliminate the side effect. However, until now, the targeting delivery has only partial been realized by passive targeting, which was called "enhanced permeability and retention" effect, and only few targeting delivery system was commercialized. Here, we designed and synthesized a hepatocarcinoma-binding peptide (A54 peptide, which was identified from a phage-display random peptide library) functionalized and PEGylated stearic acid grafted chitosan (A54-PEG-CS-SA) micelles for targeting therapy of doxorubicin. The A54-PEG-CS-SA micelles presented special internalization ability into human hepatoma cells (BEL-7402) when the cells were co-incubated with normal liver cells in vitro, and high distribution ability to liver and hepatoma tissue in vivo. In vitro and in vivo anti-tumor activity results showed that A54-PEG-CS-SA micelles loading doxorubicin treatments suppressed tumor growth more effectively and reduced toxicity compared with commercial adriamycin injection.

Quantitative study of focused ultrasound enhanced doxorubicin delivery to prostate tumor in vivo with MRI guidance

PURPOSE

The purpose of this study was to investigate the potential of MR-guided pulsed focused ultrasound (pFUS) for the enhancement of drug uptake in prostate tumors in vivo using doxorubicin (Dox).

METHODS

An antitumor drug Dox, an orthotopic animal prostate tumor model using human prostate cancer, LNCaP cell line, and a clinical FUS treatment system (InSightec ExAblate 2000) with a 1.5T GE MR scanner were used in this study. First, experiments on a tissue mimic phantom to determine the optimal acoustic power and exposure durations with a 10% duty cycle and a 1 Hz pulse rate were performed. The temperature variation was monitored using real-time MR thermometry. Second, tumor-bearing animals were treated with pFUS. There were three groups (n = 8/group): group 1 received pFUS + Dox (10 mg/kg i.v. injection immediately after pFUS exposure), group 2 received Dox only (10 mg/kg i.v. injection), and group 3 was a control. Animals were euthanized 2 h after the pFUS treatment. The Dox concentration in the treated tumors was measured by quantifying fluorescent tracers using a fluorometer. Third, the histological changes of tumors with and without pFUS treatments were evaluated. Finally, experiments were performed to study the spatial drug distribution in tumors after the pFUS treatment, in which two animals received pFUS + Dox, two animals received Dox only, and one animal was used as control. Two hours following the treatment, animals were euthanized and processed. The Dox distribution was determined using a fluorescence microscope.

RESULTS

Parametric measurements using a tissue phantom showed that the temperature increased with an increasing acoustic power (from 10 to 50 W) or sonication duration (from 10 to 60 s) with a given acoustic frequency of 1 MHz, duty cycle 10%, and pulse rate 1 Hz. A set of ultrasound parameters was identified with which the temperature elevation was less than 5 °C, which was used for nonthermal pFUS sonication. Increased Dox concentration (14.9 ± 2.5 μg/g) was measured in the pFUS-treated group compared to the Dox-only group (9.5 ± 1.6 μg/g), indicating an approximate 60% increase with p = 0.05. The results were consistent with the increased spatial drug distributions by fluorescence imaging. Histological analysis showed increased extravasation in pFUS-treated prostate tumors suggesting increased drug delivery with pFUS.

CONCLUSIONS

The results showed that pFUS-enhanced drug uptake in prostate tumors was significant. This increased uptake may be due to increased extravasation by pFUS. Optimal pFUS parameters may exist to maximize the drug uptake, and this study using Dox demonstrated a quantitative method for such systematic parametric studies. In addition, this study may provide useful data for the potential application of pFUS-mediated Dox delivery for prostate tumor therapy.

Photoswitchable nanoparticles for triggered tissue penetration and drug delivery

We report a novel nanoparticulate drug delivery system that undergoes reversible volume change from 150 to 40 nm upon phototriggering with UV light. The volume change of these monodisperse nanoparticles comprising spiropyran, which undergoes reversible photoisomerization, and PEGylated lipid enables repetitive dosing from a single administration and enhances tissue penetration. The photoswitching allows particles to fluoresce and release drugs inside cells when illuminated with UV light. The mechanism of the light-induced size switching and triggered-release is studied. These particles provide spatiotemporal control of drug release and enhanced tissue penetration, useful properties in many disease states including cancer.

A coupled discrete/continuum model for describing cancer-therapeutic transport in the lung

We propose a computational simulation framework for describing cancer-therapeutic transport in the lung. A discrete vascular graph model (VGM) is coupled to a double-continuum model (DCM) to determine the amount of administered therapeutic agent that will reach the cancer cells. An alveolar cell carcinoma is considered. The processes in the bigger blood vessels (arteries, arterioles, venules and veins) are described by the VGM. The processes in the alveolar capillaries and the surrounding tissue are represented by a continuum approach for porous media. The system of equations of the coupled discrete/continuum model contains terms that account for degradation processes of the therapeutic agent, the reduction of the number of drug molecules by the lymphatic system and the interaction of the drug with the tissue cells. The functionality of the coupled discrete/continuum model is demonstrated in example simulations using simplified pulmonary vascular networks, which are designed to show-off the capabilities of the model rather than being physiologically accurate.