Biomimetic Gold Nanoshell-Loaded Macrophage for Photothermal Biomedicine.

The purpose of this study was to investigate the effect of photothermal treatment (PTT) with gold nanoshell (ANS) using a macrophage-mediated delivery system in a head and neck squamous cell carcinoma (HNSCC) cell line. To achieve this, ANS-loaded rat macrophages (ANS-MAs) were prepared via the coculture method with ANS. The human HNSCC (FaDu cell) and macrophage (rat macrophage; NR8383 cell) hybrid spheroid models were generated by the centrifugation method to determine the possibility of using ANS-MAs as a cancer therapy. These ANS-MAs were set into the tumor and macrophage hybrid spheroid model to measure PTT efficacy. Kinetic analysis of the spheroid growth pattern revealed that this PTT process caused a decreasing pattern in the volume of the hybrid model containing ANS-MAs (p < 0.001). Comparison with empty macrophages showed harmony between ANS and laser irradiation for the generation of PTT. An annexin V/dead cell marker assay indicated that the PTT-treated hybrid model induced increasing apoptosis and dead cells. Further studies on the toxicity of ANS-MAs are needed to reveal whether it can be considered biocompatible. In summary, the ANS was prepared with a macrophage as the delivery method and protective carrier. The ANS was successfully localized to the macrophages, and their photoabsorption property was stationary. This strategy showed significant growth inhibition of the tumor and macrophage spheroid model under NIR laser irradiation. In vivo toxicology results suggest that ANS-MA is a promising candidate for a biocompatible strategy to overcome the limitations of fabricated nanomaterials. This ANS-MA delivery and PTT strategy may potentially lead to improvements in the quality of life of patients with HNSCC by providing a biocompatible, minimally invasive modality for cancer treatment.

Macrophages as delivery vehicles for anticancer agents.

The delivery of anticancer agents via passive approaches such as the enhanced permeability and retention effect is unlikely to achieve sufficient concentrations throughout the tumor volume for effective treatment. Cell-based delivery approaches using tumor tropic cells have the potential to overcome the limitations of passive approaches. Specifically, this review focuses on the use of monocytes/macrophages for the delivery of a variety of anticancer agents, including nanoparticles, chemotherapeutics and gene constructs. The efficacy of this delivery approach, both as monotherapy and in combination with light-based phototherapy modalities, has been demonstrated in numerous in vitro and animal studies, however, its clinical potential remains to be determined.

Photothermal Therapy Employing Gold Nanoparticle- Loaded Macrophages as Delivery Vehicles: Comparing the Efficiency of Nanoshells Versus Nanorods.

Macrophages (Ma) loaded with gold based nanoparticles, which convert near infrared light to heat, have been studied as targeted transport vectors for photothermal therapy (PTT) of tumors. The purpose of the experiments reported here was to compare the efficacy of gold-silica nanoshells (AuNS) and gold nanorods (AuNR) in macrophage mediated PTT. PTT efficacy was evaluated in hybrid glioma spheroids consisting of human glioma cells and either AuNS or AuNR loaded Ma, designated MaNS and MaNR respectivly. Spheroids were irradiated for 10 min. with light from an 810 nm diode laser at irradiances ranging from 0 to 28 W/cm2. PTT efficacy was determined from spheroid growth over a 14-day period. The uptake by Ma of pegylated AuNR (3.9 ± 0.9 %) was twice that of pegylated AuNS, (7.9 ± 0.7 %). Hybrid spheroids consisting of a 5:1 ratio of glioma cells to loaded Ma exhibited significant growth inhibition with MaNS when subjected to irradiances of 7 W/cm2 or greater. In contrast, no significant growth inhibition was observed for the MaNR hybrid spheroids at this 5:1 ratio, even at the highest irradiance investigated (28 W/cm2). Although AuNR were taken up by Ma in larger numbers then AuNS, MaNS were shown to have greater PTT efficacy compared to MaNR for equivalent numbers of loaded Ma.

Cell Mediated Photothermal Therapy of Brain Tumors.

Gold based nanoparticles with strong near infra-red (NIR) absorption are ideally suited for photothermal therapy (PTT) of brain tumors. The goal of PTT is to induce rapid heating in tumor tissues while minimizing thermal diffusion to normal brain. PTT efficacy is sensitively dependent on both nanoparticle concentration and distribution in tumor tissues. Nanoparticle delivery via passive approaches such as the enhanced permeability and retention (EPR) effect is unlikely to achieve sufficient nanoparticle concentrations throughout tumor volumes required for effective PTT. A simple approach for improving tumor biodsitribution of nanoparticles is the use of cellular delivery vehicles. Specifically, this review focuses on the use of monocytes/macrophages (Mo/Ma) as gold nanoparticle delivery vectors for PTT of brain tumors. Although the efficacy of this delivery approach has been demonstrated in both in vitro and animal PTT studies, its clinical potential for the treatment of brain tumors remains uncertain.

Focused ultrasound-mediated sonochemical internalization: an alternative to light-based therapies.

Activation of sonosensitizers via focused ultrasound (FUS), i.e., sonodynamic therapy has been proposed as an extension to light-activated photodynamic therapy for the treatment of brain as well as other tumors. The use of FUS, as opposed to light, allows treatment to tumor sites buried deep within tissues as well as through the intact skull. We have examined ultrasonic activation of sonosensitizers together with the anticancer agent bleomycin (BLM), i.e., sonochemical internalization (SCI). SCI is a technique that utilizes FUS for the enhanced delivery of endo-lysosomal trapped macromolecules into the cell cytoplasm in a similar manner to light-based photochemical internalization. The released agent can, therefore, exert its full biological activity, in contrast to being degraded by lysosomal hydrolases. Our results indicate that, compared to drug or FUS treatment alone, FUS activation of the sonosensitizer AlPcS2a together with BLM significantly inhibits the ability of treated glioma cells to grow as three-dimensional tumor spheroids in vitro.

Macrophages as nanoparticle delivery vectors for photothermal therapy of brain tumors.

Certain types of stem and immune cells, which have an innate ability to target and infiltrate tumors, can be utilized as vectors to deliver several types of anticancer agents. In particular monocytes have the advantage of carrying relatively large payloads of therapeutic nanomaterials, can be patient derived in large numbers and are able to actively infiltrate tumors despite many barriers often present in the microenvironment. Monocytes can selectively cross the compromised blood-brain barrier surrounding brain tumors and are known to actively migrate to hypoxic tumor regions. Of particular interest is the observation that, following near-infrared exposure of tumors containing gold-nanoshell-loaded macrophages, sufficient hyperthermia can be generated to suppress tumor growth. Collectively, these findings demonstrate the potential of monocytes as nanoparticle delivery vectors for several types of site specific light-based cancer therapies.

Nanoparticle-loaded macrophage-mediated photothermal therapy: potential for glioma treatment.

Gold-based nanoparticles have been used in a number of therapeutic and diagnostic applications. The purpose of this study was to investigate the efficacy of gold-silica nanoshells (AuNS) in photothermal therapy (PTT) of rat gliomas. Rat alveolar macrophages (Ma) were used as nanoparticle delivery vectors. Uptake of AuNS (bare and PEGylated) was investigated in Ma. AuNS were incubated with Ma for 24 h. Phase contrast microscopy was used to visualize the distribution of loaded Ma in three-dimensional glioma spheroids. PTT efficacy was evaluated for both empty (Ma) and AuNS-loaded Ma (Ma(NS)) in both monolayers and spheroids consisting of C6 rat glioma cells and Ma. Monolayers/spheroids were irradiated for 5 min with light from an 810-nm diode laser at irradiances ranging from 7 to 28 W cm(-2). Monolayer survival was evaluated using a 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS) assay while PTT efficacy in spheroids was determined from growth kinetics and live/dead fluorescence microscopy. PTT efficacy was investigated in vivo using a Sprague-Dawley rat glioma model. Five rats received direct intracranial injection of a mixture of 10(4) C6 glioma cells and, 2 days later, an equal number of Ma(NS). Three rats received laser treatment (810 nm; 10 min; 1 W) while the remaining two served as controls (no laser treatment). The uptake ratio of bare to PEGylated AuNS by Ma was 4:1. A significant photothermal effect was observed in vitro, albeit at relatively high radiant exposures (2.1-4.2 kJ cm(-2)). PTT proved effective in vivo in preventing or delaying tumor development in the PTT-treated animals.

Combined concurrent photodynamic and gold nanoshell loaded macrophage-mediated photothermal therapies: an in vitro study on squamous cell head and neck carcinoma.

BACKGROUND AND OBJECTIVE: Treatment modalities, such as hyperthermia and photodynamic therapy (PDT) have been used in the treatment of a variety of head and neck squamous cell carcinoma (HNSCC), either alone or as an adjuvant therapy. Macrophages loaded with gold nanoshells, which convert near-infrared light to heat, can be used as transport vectors for photothermal hyperthermia of tumors. The purpose of this study was to investigate the effects of combined macrophage mediated photothermal therapy (PTT) and PDT on HNSCC cells. STUDY DESIGN/MATERIALS AND METHODS: Gold nanoshell loaded rat macrophages either alone or combined with human FaDu squamous cells in hybrid monolayers were subjected to PTT, PDT, or a simultaneous combination of the two light treatments. Therapies were given concurrently employing two laser light sources of λ = 670 nm (PDT) and λ = 810 nm (PTT), respectively. RESULTS: Significant uptake of gold nanospheres (AuNS) by rat alveolar macrophages was observed thus providing the rationale for their use as delivery vectors. Viability of the AuNS-loaded Ma was reduced to 35 and 12% of control values at an irradiance of 14 or 28 W/cm(2) administered over a 5 minute period respectively. No significant cytotoxicity was observed for empty Ma for similar PTT exposure. AlPcS2a mediated PDT at a fluence level of 0.25 J/cm(2) and PTT at 14 W/cm(2) irradiance had little effect on cell viability for the FaDu/Ma (ratio 2:1) hybrid monolayers. In contrast, combined treatment reduced the cell viability to less than 40% at these same laser power settings. CONCLUSIONS: The results of this study provide proof of concept for the use of macrophages as a delivery vector of AuNS for photothermal enhancement of the effects of PDT on squamous cell carcinoma. A significant synergy was demonstrated with combined PDT and PTT compared to each modality applied separately.

Macrophages as cell-based delivery systems for nanoshells in photothermal therapy.

Site-specific delivery of nanoparticles poses a significant challenge, especially in the brain where the blood-brain barrier prevents the entry of most therapeutic compounds including nanoparticle-based anti-cancer agents. In this context, the use of macrophages as vectors for the delivery of gold-silica nanoshells to infiltrating gliomas will be reviewed in this article. Gold-silica nanoshells are readily phagocytosed by macrophages without any apparent toxic effects, and the results of in vitro studies have demonstrated the migratory potential of nanoshell-loaded macrophages in human glioma spheroids. Of particular interest is the observation that, after near-infrared exposure of spheroids containing nanoshell-loaded macrophages, sufficient heat was generated to suppress spheroid growth. Collectively, these findings demonstrate the potential of macrophages as nanoshell delivery vectors for photothermal therapy of gliomas, and they certainly provide the basis for future animal studies.

Photothermal treatment of glioma; an in vitro study of macrophage-mediated delivery of gold nanoshells.

One of the major factors that limits the treatment effectiveness for gliomas is the presence of the blood-brain barrier (BBB) which protects infiltrating glioma cells from the effects of anti-cancer agents. Circulating monocytes/macrophages (Ma) have a natural ability to traverse the intact and compromised BBB and loaded with anti cancer agents could be used as vectors to target tumors and surrounding tumor infiltrated tissue. Nanoshells (NS) are composed of a dielectric core (silica) coated with an ultrathin gold layer which converts absorbed near-infrared light (NIR) to heat with an extremely high efficacy and stability. We have investigated the effects of exposure to laser NIR on multicell human glioma spheroids infiltrated with empty (containing no nanoshells) or nanoshell loaded macrophages. Our results demonstrated that; (1) macrophages could efficiently take up bare or coated (PEGylated) gold NS: (2) NS loaded macrophages infiltrated into glioma spheroids to the same or, in some cases, to a greater degree than empty Ma; (3) NIR laser irradiation of spheroids incorporating NS loaded macrophages resulted in complete growth inhibition in an irradiance dependent manner, and (4) spheroids infiltrated with empty macrophages had growth curves identical to untreated control cultures. The results of this study provide proof of concept for the use of macrophages as a delivery vector of NS into gliomas for photothermal ablation and open the possibility of developing such regimens for patient treatment.

Multicell tumor spheroids in photodynamic therapy.

BACKGROUND AND OBJECTIVES: Multicell spheroids (MCSs) represent a simple in vitro system ideally suited for studying the effects of a wide variety of investigational treatments including photodynamic therapy (PDT). STUDY DESIGN/MATERIALS AND METHODS: In the first section of this review study, an overview of the current literature on MCS in PDT will be presented. Knowledge of basic PDT parameters has been gained from numerous MCS studies, in particular, the mechanisms of sensitizer photobleaching have been elucidated. MCSs have also proven useful for the study of complex PDT treatment regimens including multiple treatments and combined therapies involving PDT and ionizing radiation or hyperthermia. The purpose of the second part of this review is to present results from recent studies in our laboratory aimed at developing MCS models suitable for investigating tumor cell invasion and angiogenesis-processes characteristic of high-grade gliomas. RESULTS AND CONCLUSION: To that end, progress has recently been made to develop a more accurate in vivo brain tumor model consisting of biopsy-derived human tumor spheroids implanted into the brains of immunodeficient rats. Finally, recent work suggests that computer simulations may prove useful to describe the growth of MCS and predict the effects of investigational therapies including PDT. Such in silico models have made a number of counterintuitive predictions that have been verified in vitro and, as such, could guide the development of improved therapeutics.

Enhanced cytotoxic effects of 5-aminolevulinic acid-mediated photodynamic therapy by concurrent hyperthermia in glioma spheroids.

During photodynamic therapy (PDT) both normal and pathological brain tissue, in close proximity to the light source, can experience significant temperature increases. The purpose of this study was to investigate the anti-tumor effects of concurrent 5-aminolevulinic acid (ALA)-mediated PDT and hyperthermia (HT) in human and rat glioma spheroids. Human or rat glioma spheroids were subjected to PDT, HT, or a combination of the two treatments. Therapies were given concurrently to simulate the conditions that will occur during patient PDT. Predictions of diffusion theory suggest that brain tissue immediately adjacent to a spherical light applicator may experience temperature increases approaching 8 degrees C for laser input powers of 2 W. In the in vitro model employed here, HT had no effect on spheroid survival at temperatures below 49 degrees C, while sub-threshold fluence PDT results in only modest decrease in survival. HT (40-46 degrees C) and PDT interact in a synergistic manner if the two treatments are given concurrently. The degree of synergism increases with increasing temperature and light fluence. Apoptosis is the primary mode of cell death following both low-fluence rate PDT and combined HT + PDT.