Mild Local Hyperthermia Research Articles

Pulsed Photothermal Therapy of Solid Tumors as a Precondition for Immunotherapy.

Photothermal therapy (PTT) refers to the use of plasmonic nanoparticles to convert electromagnetic radiation in the near infrared region to heat and kill tumor cells. Continuous wave lasers have been used clinically to induce PTT, but the treatment is associated with heat-induced tissue damage that limits usability. Here, the engineering and validation of a novel long-pulsed laser device able to induce selective and localized mild hyperthermia in tumors while reducing the heat affected zone and unwanted damage to surrounding tissue are reported. Long-pulsed PTT induces acute necrotic cell death in heat affected areas and the release of tumor associated antigens. This antigen release triggers maturation and stimulation of CD80/CD86 in dendritic cells in vivo that primes a cytotoxic T cell response. Accordingly, long-pulsed PTT enhances the therapeutic effects of immune checkpoint inhibition and increases survival of mice with bladder cancer. Combined, the data promote long-pulsed PTT as a safe and effective strategy for enhancing therapeutic responses to immune checkpoint inhibitors while minimizing unwanted tissue damage.

Protocol of the HISTOTHERM study: assessing the response to hyperthermia and hypofractionated radiotherapy in recurrent breast cancer.

Breast cancer is globally the leading cancer in women, and despite the high 5-year survival rate the most frequent cause of cancer related deaths. Surgery, systemic therapy and radiotherapy are the three pillars of curative breast cancer treatment. However, locoregional recurrences frequently occur after initial treatment and are often challenging to treat, amongst others due to high doses of previous radiotherapy treatments. Radiotherapy can be combined with local hyperthermia to sensitize tumor cells to radiation and thereby significantly reduce the required radiation dose. Therefore, the combination treatment of mild local hyperthermia, i.e. locally heating of the tissue to 39-43°C, and re-irradiation with a reduced total dose is a relevant treatment option for previously irradiated patients. The mechanisms of this effect in the course of the therapy are to date not well understood and will be investigated in the HISTOTHERM study. Patients with local or (loco)regional recurrent breast cancer with macroscopic tumors are included in the study. Local tumor control is evaluated clinically and histologically during the course of a combination treatment of 60 minutes mild superficial hyperthermia (39 - 43°C) using water-filtered infrared A (wIRA) irradiation, immediately followed by hypofractionated re-irradiation with a total dose of 20-24 Gy, administered in weekly doses of 4 Gy. Tumor and tumor stroma biopsies as well as blood samples will be collected prior to treatment, during therapy (at a dose of 12 Gy) and in the follow-up to monitor therapy response. The treatment represents the standard operating procedure for hyperthermia plus re-irradiation. Various tissue and blood-based markers are analyzed. We aim at pinpointing key mechanisms and markers for therapy response which may help guiding treatment decisions in future. In addition, quality of life in the course of treatment will be assessed and survival data will be evaluated. The study is registered at the German Clinical Trials Register, Deutsches Register Klinischer Studien (DRKS00029221).

A novel technique to harvest bone autografts with mild local hyperthermia and enhanced osteogenic bone quality: a preclinical study in dogs

BackgroundGuided bone regeneration (GBR) involves collecting bone autografts with high bio-quality and efficiency. The current non-irrigated low-speed drilling has been limited for broader application in bone autograft harvest due to its low efficiency, inability to conduct buccal cortical perforation, and dependence on simultaneous implant placement. Increasing the drilling speed helps improve the efficiency but may incur thermal-mechanical bone damage. Most studies have addressed thermal reactions during bone drilling on non-vital models, which is irrelevant to clinical scenarios. Little has been known about bone’s in vivo thermal profiles under non-irrigated higher-speed drilling and its influences on the resulting bone chips.AimA novel technique for bone harvest and cortical perforation via in-situ non-irrigated higher-speed drilling was proposed and investigated for the first time.MethodsThe third mandible premolars of eight beagles were extracted and healed for three months. Sixteen partial edentulous sites (left and right) were randomized into four groups for bone autograft harvest without irrigation: chisel, 50 rpm drilling, 500 rpm drilling, and 1000 rpm drilling. Bone chips were harvested on the buccal plates of the missing tooth. An infrared camera and an implantable thermocouple collaboratively monitored in vivo real-time bone temperature at the drilling sites. In vitro performances of cells from bone chips, including cell number, viability, proliferation, migration, ALP activity, in vitro mineralization, mRNA transcriptional level of osteogenic genes and heat shock protein 70 (HSP-70), and HSP-70 expression at the protein level were also studied.Results500 rpm produced mild local hyperthermia with a 2–6 °C temperature rise both on the cortical surface and inside the cortical bone. It also held comparable or enhanced cell performances such as cell number, viability, proliferation, migration, ALP activity, in vitro mineralization, and osteogenic genes expression.ConclusionsIn-situ non-irrigated higher-speed drilling at 500 rpm using a screw drill is versatile, efficient, and thermal friendly and improves the bio-quality of bone chips. Our novel technique holds clinical translational potential in GBR application.

Microfluidic fabricated bisdemethoxycurcumin thermosensitive liposome with enhanced antitumor effect

Bisdemethoxycurcumin (BDMC) is the main active ingredient that is isolated from Zingiberaceae plants, wherein it has excellent anti-tumor effects. However, insolubility in water limits its clinical application. Herein, we reported a microfluidic chip device that can load BDMC into the lipid bilayer to form BDMC thermosensitive liposome (BDMC TSL). The natural active ingredient glycyrrhizin was selected as the surfactant to improve solubility of BDMC. Particles of BDMC TSL had small size, homogenous size distribution, and enhanced cultimulative release in vitro. The anti-tumor effect of BDMC TSL on human hepatocellular carcinomas was investigated via 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide method, live/dead staining, and flowcytometry. These results showed that the formulated liposome had a strong cancer cell inhibitory, and presented a dose-dependent inhibitory effect on migration. Further mechanistic studies showed that BDMC TSL combined with mild local hyperthermia could significantly upregulate B cell lymphoma 2 associated X protein levels and decrease B cell lymphoma 2 protein levels, thereby inducing cell apoptosis. The BDMC TSL that was fabricated via microfluidic device were decomposed under mild local hyperthermia, which could beneficially enhance the anti-tumor effect of raw insoluble materials and promote translation of liposome.

Reprint of: Clearance of multiple cutaneous warts by targeting a single lesion: A randomized comparative evaluation of mild local hyperthermia versus cryotherapy

Reprint of: Clearance of multiple cutaneous warts by targeting a single lesion: A randomized comparative evaluation of mild local hyperthermia versus cryotherapy

Harnessing immunotherapy to enhance the systemic anti-tumor effects of thermosensitive liposomes.

Chemotherapy plays an important role in debulking tumors in advance of surgery and/or radiotherapy, tackling residual disease, and treating metastatic disease. In recent years many promising advanced drug delivery strategies have emerged that offer more targeted delivery approaches to chemotherapy treatment. For example, thermosensitive liposome-mediated drug delivery in combination with localized mild hyperthermia can increase local drug concentrations resulting in a reduction in systemic toxicity and an improvement in local disease control. However, the majority of solid tumor-associated deaths are due to metastatic spread. A therapeutic approach focused on a localized target area harbors the risk of overlooking and undertreating potential metastatic spread. Previous studies reported systemic, albeit limited, anti-tumor effects following treatment with thermosensitive liposomal chemotherapy and localized mild hyperthermia. This work explores the systemic treatment capabilities of a thermosensitive liposome formulation of the vinca alkaloid vinorelbine in combination with mild hyperthermia in an immunocompetent murine model of rhabdomyosarcoma. This treatment approach was found to be highly effective at heated, primary tumor sites. However, it demonstrated limited anti-tumor effects in secondary, distant tumors. As a result, the addition of immune checkpoint inhibition therapy was pursued to further enhance the systemic anti-tumor effect of this treatment approach. Once combined with immune checkpoint inhibition therapy, a significant improvement in systemic treatment capability was achieved. We believe this is one of the first studies to demonstrate that a triple combination of thermosensitive liposomes, localized mild hyperthermia, and immune checkpoint inhibition therapy can enhance the systemic treatment capabilities of thermosensitive liposomes.

Bio-interface engineering of MXene nanosheets with immobilized lysozyme for light-enhanced enzymatic inactivation of methicillin-resistant Staphylococcus aureus

Being a unique biocatalyst to hydrolyse structural polysaccharides on the cell wall of bacteria, lysozyme can slow down bacterial resistance caused by antibiotic overdose treatments, however, efficient activation of lysozyme activities under pathogenic microenvironments remains challenging. Herein, a bio-interface engineering strategy was proposed for the remote modulation of thermoresistant lysozyme upon rationally designed photothermal nanoplatforms. For this, Ti3C2TX MXene nanosheets were functionalized by polydopamine (PDA) surface chemistry to enhance photothermal effects and performance durability, during which lysozyme biomacromolecules were immobilized at such a two-dimensional hybrid interface via intermolecular electrostatic affinity. The integrated nanoplatform (denoted as M@P@Lyso), with an optimal high light-to-heat conversion efficiency of 46.88%, realized not only precision control of local heat but also photo-responsive up-regulation for bio-catalysis of laden lysozyme. As a result, in vitro and in vivo antibacterial experiments revealed that M@P@Lyso could effectively inhibit the proliferation of methicillin-resistant Staphylococcus aureus and accelerated wound disinfection of mice with negligible biological toxicities. The outstanding antibacterial activities of M@P@Lyso were attributed to the photo-enhanced lysozyme activity, assisted by bacterial death caused by the mild local hyperthermia and the physical destruction derived from the M@PDA. This work exemplified a solution to the bacterial resistance threats via stimuli-responsive enzymatic nanoplatforms.

Clearance of multiple cutaneous warts by targeting a single lesion: A randomized comparative evaluation of mild local hyperthermia versus cryotherapy

To the Editor: Multiple mucocutaneous warts are common in patients due to virus spreading or self-inoculation, as exemplified by 22.2% of the patients with plantar warts having more than one lesion.1 Specific immune responses against human papillomavirus-harboring lesions contribute to self-regression or treatment-mediated clearance of warts. As such, the treatment-induced immune response to one target lesion could likely initiate the immune-mediated clearance of untargeted or remote lesions in patients with multiple warts containing the same human papillomavirus types.

Feasibility of ultrasound tomography-guided localized mild hyperthermia using a ring transducer: Ex vivo and in silico studies.

As of 2022, breast cancer continues to be the most diagnosed cancer worldwide. This problem persists within the United States as well, as the American Cancer Society has reported that ∼12.5% of women will be diagnosed with invasive breast cancer over the course of their lifetime. Therefore, a clinical need continues to exist to address this disease from a treatment and therapeutic perspective. Current treatments for breast cancer and cancers more broadly include surgery, radiation, and chemotherapy. Adjuncts to these methods have been developed to improve the clinical outcomes for patients. One such adjunctive treatment is mild hyperthermia therapy (MHTh), which has been shown to be successful in the treatment of cancers by increasing effectiveness and reduced dosage requirements for radiation and chemotherapies. MHTh-assisted treatments can be performed with invasive thermal devices, noninvasive microwave induction, heating and recirculation of extracted patient blood, or whole-body hyperthermia with hot blankets. One common method for inducing MHTh is by using microwave for heat induction and magnetic resonance imaging for temperature monitoring. However, this leads to a complex, expensive, and inaccessible therapy platform. Therefore, in this work we aim to show the feasibility of a novel all-acoustic MHTh system that uses focused ultrasound (US) to induce heating while also using US tomography (UST) to provide temperature estimates. Changes in sound speed (SS) have been shown to be strongly correlated with temperature changes and can therefore be used to indirectly monitor heating throughout the therapy. Additionally, these SS estimates allow for heterogeneous SS-corrected phase delays when heating complex and heterogeneous tissue structures. Feasibility to induce localized heat in tissue was investigated in silico with a simulated breast model, including an embedded tumor using continuous wave US. Here, both heterogenous acoustic and thermal properties were modeled in addition to blood perfusion. We further demonstrate, with ex vivo tissue phantoms, the feasibility of using ring-based UST to monitor temperature by tracking changes in SS. Two phantoms (lamb tissue and human abdominal fat) with latex tubes containing varied temperature flowing water were imaged. The measured SS of the water at each temperature were compared against values that are reported in literature. Results from ex vivo tissue studies indicate successful tracking of temperature under various phantom configurations and ranges of water temperature. The results of in silico studies show that the proposed system can heat an acoustically and thermally heterogenous breast model to the clinically relevant temperature of 42°C while accounting for a reasonable time needed to image the current cross section (200ms). Further, we have performed an initial in silico study demonstrating the feasibility of adjusting the transmit waveform frequency to modify the effective heating height at the focused region. Lastly, we have shown in a simpler 2D breast model that MHTh level temperatures can be maintained by adjusting the transmit pressure intensity of the US ring. This work has demonstrated the feasibility of using a 256-element ring array transducer for temperature monitoring; however, future work will investigate minimizing the difference between measured SS and the values shown in literature. A hypothesis attributes this bias to potential volumetric average artifacts from the ray-based SS inversion algorithm that was used, and that moving to a waveform-based SS inversion algorithm will greatly improve the SS estimates. Additionally, we have shown that an all-acoustic MHTh system is feasible via in silico studies. These studies have indicated that the proposed system can heat a tumor within a heterogenous breast model to 42°C within a narrow time frame. This holds great promise for increasing the accessibility and reducing the complexity of a future all-acoustic MHTh system.

Preclinical Studies in Small Animals for Advanced Drug Delivery Using Hyperthermia and Intravital Microscopy.

Simple SummaryMild hyperthermia is a technique that induces a local tumor temperature increase up to 43.0 °C. In this paper, we introduce three devices that could be used to apply hyperthermia in small animals in combination with intravital microscopy for the real-time visualization of in vivo intratumoral events such as drug delivery.This paper presents three devices suitable for the preclinical application of hyperthermia via the simultaneous high-resolution imaging of intratumoral events. (Pre)clinical studies have confirmed that the tumor micro-environment is sensitive to the application of local mild hyperthermia. Therefore, heating is a promising adjuvant to aid the efficacy of radiotherapy or chemotherapy. More so, the application of mild hyperthermia is a useful stimulus for triggered drug release from heat-sensitive nanocarriers. The response of thermosensitive nanoparticles to hyperthermia and ensuing intratumoral kinetics are considerably complex in both space and time. To obtain better insight into intratumoral processes, longitudinal imaging (preferable in high spatial and temporal resolution) is highly informative. Our devices are based on (i) an external electric heating adaptor for the dorsal skinfold model, (ii) targeted radiofrequency application, and (iii) a microwave antenna for heating of internal tumors. These models, while of some technical complexity, significantly add to the understanding of effects of mild hyperthermia warranting implementation in research on hyperthermia.

Promoting Nanoparticle Delivery Efficiency to Tumors by Locally Increasing Blood Flow There.

Enhancing the tumor-targeted delivery efficiency of nanoparticles is necessary for improving their therapeutic efficacy, yet how to fulfill this, especially in a practical manner, remains a significant challenge. Noticing that major organs compete effectively with tumors for nanoparticles, we herein carried out meta-analysis on nanoparticle delivery efficiency to major organs and tumors. Notably, in major organs, cellular uptake alone cannot explain why one organ has higher nanoparticle delivery efficiency than another; indeed, blood flow through an organ may facilitate nanoparticle delivery efficiency there as well. Intriguingly, such a facilitative role can be extrapolated to tumors, according to meta-analysis on the relationship of tumor-targeted delivery efficiency of nanoparticles versus blood flow through tumors of different weights. Indeed, using local mild hyperthermia as a model for modalities capable of increasing tumor blood flow, we observed a ∼3-fold increase in tumor-targeted delivery efficiency in the meta-analysis on studies involving both nanoparticles and local mild hyperthermia. This work identifies tumor blood flow as a crucial factor in determining tumor-targeted delivery efficiency of nanoparticles and suggests increasing tumor blood flow as an alternative way to boost tumor-targeted delivery efficiency of nanoparticles.

Tuning the phase transition temperature of hybrid Span60-L64 thermoresponsive niosomes: Insights from fluorescence and Raman spectroscopy

In this work, we report the formation of hybrid niosome vesicles, prepared using non-ionic surfactant Span60 (S60) and triblock copolymer L64 for the first time, along with cholesterol. The prepared S60-L64 hybrid niosomes with different compositions are compared with pure L64 and S60 niosomes, and they are characterized using Dynamic Light Scattering (DLS), zeta potential, Scanning Electron Microscopy (SEM) techniques. Gel to liquid phase transition behaviour of the niosomes are studied in detail, using steady-state fluorescence and Raman spectroscopy. The phase transition temperature (Tm) of vesicles is tuned sequentially on the addition of increasing mole percentage of S60 to pure L64. 1-Naphthol, a polarity sensitive fluorescent probe, is loaded in-situ and used to study the micro-environmental changes in the niosome over a wide range of temperatures to determine the Tm of the vesicles. The transformations of the niosome bilayer in the gel, pre-transition and liquid phase are schematically shown and discussed elaborately in accordance with the fluorescence behaviour of 1-Naphthol. As a direct and label-free technique, Raman spectroscopy is also used to investigate the bilayer arrangement of the niosome around Tm. The behaviour of different vibrational modes in the hydrocarbon chain of the niosome at different temperatures is successfully used to determine the Tm of the vesicles. Finally, the phase transition temperature of an appropriate hybrid niosome is determined as 40 °C, which can be used as an efficient thermoresponsive drug delivery system within the physiological body temperature limit at local mild hyperthermia condition.

Hybrid System for Local Drug Delivery and Magnetic Hyperthermia Based on SPIONs Loaded with Doxorubicin and Epirubicin.

Cancer is one of the most common causes of death worldwide, thus new solutions in anticancer therapies are highly sought after. In this work, superparamagnetic iron oxide nanoparticles (SPIONs) conjugated with anticancer drugs are synthesized and investigated as potential magnetic drug nanocarriers for local drug delivery and mild magnetic hyperthermia. We have obtained a hybrid system loaded with holmium and anticancer drugs and thoroughly studied it with respect to the size, morphology, surface modifications and magnetic properties, and interactions with the model of biological membranes, cytotoxicity. We present that nanoparticles having a round shape and size 15 nm are successfully stabilized to avoid their agglomeration and modified with doxorubicin or epirubicin within a controlled way. The number of drugs loaded into the SPIONs was confirmed with thermogravimetry. The hybrid based on SPIONs was investigated in touch with model biological membranes within the Langmuir-Blodgett technique, and results show that modified SPION interacts effectively with them. Results obtained with magnetic hyperthermia and biological studies confirm the promising properties of the hybrid towards future cancer cell treatment.

Thermosensitive Liposomes Encapsulating Anti-Cancer Agent Lomustine, and Contrast Medium Iohexol, for Thermochemotherapy: Preparation, Characterization, and In Vivo Evaluation.

Thermosensitive liposome-based drug delivery systems (DDS) are powerful tools for site-specific delivery of chemotherapeutics, especially when combined with regional hyperthermia. The objective of this work was to develop a novel thermosensitive liposomal DDS loaded with lomustine, a chemotherapeutic compound, and iohexol, a contrast medium for visualization by CT. Thermosensitive compound liposomes (TSCLs) composed of DPPC were prepared by reverse-phase evaporation and investigated for encapsulation efficiency, temperature-sensitivity, release kinetics, and In Vivo pharmacokinetics. The size and zeta-potential of TSCLs ranged from 250 to 300 nm and -15 to -30 mV, respectively. At 41 °C, TSCLs were shown to release over 90% of iohexol and lomustine within 4 h. The in vitro release profiles of iohexol and lomustine at 41 °C conformed to first-order kinetics and Weibullmodel, respectively. Phase-transition did not occur after incorporation of cholesterol and soybean phospholipids. In Vivo evaluation performed with C6 glioma model rats proved the prolonged half-lives and improved bioavailability by liposomal encapsulation for both compounds under mild local hyperthermia. The TSCLs used in this study may offer a clinically promising mean of increasing efficacy and controlling toxicity.

Hypoxia-activated ROS burst liposomes boosted by local mild hyperthermia for photo/chemodynamic therapy

Single reactive oxygen species (ROS)-mediated therapy, photodynamic therapy (PDT) or chemodynamic therapy (CDT) is severely hindered in hypoxic solid tumor. Herein, to address the urgent challenge, a hypoxia-activated ROS burst liposome has been fabricated to achieve synergistic PDT/CDT that is initiated by the structural dissociation of poly(metronidazole) liposome in hypoxic tumor microenvironment (TME). The therapeutic enhancement of our ROS-blasting treatment is simultaneously regulated by external light-initiated PDT and endogenous iron oxide nanoclusters-triggered CDT, which is synergistically boosted and amplified by localized mild hyperthermia under 808/660 nm coirradiation. More importantly, in vitro and in vivo experiments demonstrate that electron-affinic poly(aminoimidazole) product from hypoxia-responsive transition of poly(metronidazole) polymers could efficiently enhance hypoxic cell apoptosis and induce solid tumor ablation. Thus, this work offers a potential hypoxia-activated ROS burst-PDT/CDT strategy with a superior antitumor efficacy, highlighting a promising clinical application.

Abstract B7: Changing the field: Magnetic particle imaging and localized RF hyperthermia in cancer immunology

Abstract The success of cancer immunotherapy has driven the rapid growth of research into immuno-oncology, which in turn has fueled the need to be able to determine the location of a variety of immune cells in solid tumors and systemically over time. There is a strong association between response to the new checkpoint inhibitor treatments and the immune status of a tumor, and new methods to determine or modify that status are needed. Magnetic particle imaging (MPI) is a novel preclinical molecular imaging technique that can be used to noninvasively track iron oxide-tagged immune (and other) cells in vivo. By combining accurate quantitation, specificity, and depth-independent 3D imaging, MPI can provide information on macrophage and other cellular biodistributions over time, for weeks or even months. In addition to being an imaging modality, MPI can be used for localized theragnostics and drug delivery. The same or similar nanoparticles that are used for imaging can also be used to generate heat for localized magnetic hyperthermia. Imaging is used to determine the distribution and amount of iron in a sample, then MPI-based magnetic gradients are used to limit the hyperthermia to only a small, adjustable “field-free region” in the sample. Heating can be severe, until the start of apoptosis, or mild, to promote a localized immune response, which can be beneficial as an adjunct to both radiation and immune therapies, improving radiation therapy efficacy and potentially turning “cold,” immunologically unresponsive tumors “hot.” The nanoparticles used for both imaging and hyperthermia are superparamagnetic iron-oxide, with considerable differences in imaging sensitivity and resolution and hyperthermia efficiency possible depending on the size, shape, and composition of the particles. Unlike many other molecular imaging modalities, resolution for MPI depends strongly on the nanoparticle being imaged, with resolutions from 100 um to nearly 2 mm being possible with the same imaging system simply by using different particles. In addition, the design and development of heat-sensitive nanoparticles and liposomes for use with mild hyperthermia is an important aspect of MPI development. MPI is a rapidly growing molecular imaging technique, with applications across many biomedical fields, including oncology. The noninvasive, 3D tracking of immune cell distributions systemically in vivo is an important aspect of understanding immune-tumor interactions, and the combination of imaging nanoparticles along with using them for localized mild or severe RF hyperthermia is a powerful addition to the toolkit for oncology research. Results and instrumentation for both immune cell tracking and localized magnetic hyperthermia will be discussed. Citation Format: James R. Mansfield, Jeffrey M. Gaudet, Gang Ren, Daniel Hensley, Patrick Goodwill, Max Wintermark. Changing the field: Magnetic particle imaging and localized RF hyperthermia in cancer immunology [abstract]. In: Proceedings of the AACR Special Conference on Tumor Immunology and Immunotherapy; 2019 Nov 17-20; Boston, MA. Philadelphia (PA): AACR; Cancer Immunol Res 2020;8(3 Suppl):Abstract nr B7.

A combination drug delivery system employing thermosensitive liposomes for enhanced cell penetration and improved in vitro efficacy.

Drug-loaded thermosensitive liposomes are investigated as drug delivery systems in combination with local mild hyperthermia therapy due to their capacity to release their cargo at a specific temperature range (40-42°C). Additional benefit can be achieved by the development of such systems that combine two different anticancer drugs, have cell penetration properties and, when heated, release their drug payload in a controlled fashion. To this end, liposomes were developed incorporating at low concentration (5mol%) a number of monoalkylether phosphatidylcholine lipids, encompassing the platelet activating factor, PAF, and its analogues that induce thermoresponsiveness and have anticancer biological activity. These thermoresponsive liposomes were efficiently (>90%) loaded with doxorubicin (DOX), and their thermal properties, stability and drug release were investigated both at 37 ◦C and at elevated temperatures. In vitro studies of the most advantageous liposomal formulation containing the methylated PAF derivative (methyl-PAF, edelfosine), an established antitumor agent, were performed on human prostate cancer cell lines. This system exhibits controlled release of DOX at 40-42°C, enhanced cell uptake due to the presence of methyl-PAF, and improved cell viability inhibition due to the combined action of both medications.

Anti-Metastatic Benefits Produced by Hyperthermia and a CCL3 Derivative.

Significant numbers of malignant tumor cells that have spread to surrounding tissues and other distant organs are often too small to be picked up in a diagnostic test, and prevention of even such small metastases should improve patient outcomes. Using a mouse model, we show in this article that intravenous administration of a human CCL3 variant carrying a single amino acid substitution after mild local hyperthermia not only induces tumor growth inhibition at the treated site but also inhibits metastasis. Colon26 adenocarcinoma cells (1 × 105 cells/mouse) were grafted subcutaneously into the right hind leg of syngeneic BALB/c mice and after nine days, when tumor size reached ~11 mm in diameter, the local tumor mass was exposed to high-frequency waves, by which intratumoral temperature was maintained at 42 °C for 30 min. Mice received the CCL3 variant named eMIP (2 μg/mouse/day) intravenously for five consecutive days starting one day after heat treatment. We found that tumor growth in eMIP recipients after hyperthermia was inhibited markedly but no effect was seen in animals treated with either hyperthermia or eMIP alone. Furthermore, the number of lung metastases evaluated at 18 days after hyperthermia treatment was dramatically reduced in animals receiving the combination therapy compared with all other controls. These results encourage future clinical application of this combination therapy.

Effects of p53 Status of Tumor Cells and Combined Treatment With Mild Hyperthermia, Wortmannin or Caffeine on Recovery From Radiation-Induced Damage

BackgroundThe aim of the study was to examine the dependency of p53 status and the usefulness of mild hyperthermia (MHT) as an inhibitor of recovery from radiation-induced damage, referring to the response of quiescent (Q) tumor cell population.MethodsHuman head and neck squamous cell carcinoma cells transfected with mutant TP53 (SAS/mp53) or with neo vector (SAS/neo) were injected subcutaneously into left hind legs of nude mice. Tumor-bearing mice received 5-bromo-2’-deoxyuridine (BrdU) continuously to label all intratumor proliferating (P) cells. They received high dose-rate γ-ray irradiation (HDR) immediately followed by localized MHT (40 °C for 2 h), or caffeine or wortmannin administration, or low dose-rate γ-ray irradiation simultaneously with localized MHT or caffeine or wortmannin administration. Nine hours after the start of irradiation, the tumor cells were isolated and incubated with a cytokinesis blocker, and the micronucleus (MN) frequency in cells without BrdU labeling (= Q cells) was determined using immunofluorescence staining for BrdU.ResultsSAS/neo tumor cells, especially intratumor Q cell populations, showed a marked reduction in sensitivity due to the recovery from radiation-induced damage, compared with the total or Q tumor cells within SAS/mp53 tumors that showed little recovery capacity. The recovery from radiation-induced damage was thought to be a p53-dependent event. In both total and Q tumor cells within SAS/neo tumors, especially the latter, MHT efficiently suppressed the reduction in sensitivity caused by leaving an interval between HDR irradiation and the assay and decreasing the irradiation dose-rate, as well as the combination with wortmannin administration.ConclusionsFrom the viewpoint of solid tumor control as a whole, including intratumor Q-cell control, non-toxic MHT is useful for suppressing the recovery from radiation-induced damage, as well as wortmannin treatment combined with γ-ray irradiation.

Smart thermosensitive liposomes for effective solid tumor therapy and in vivo imaging.

In numerous studies, liposomes have been used to deliver anticancer drugs such as doxorubicin to local heat-triggered tumor. Here, we investigate: (i) the ability of thermosensitive liposomal nanoparticle (TSLnp) as a delivery system to deliver poorly membrane-permeable anticancer drug, gemcitabine (Gem) to solid pancreatic tumor with the aid of local mild hyperthermia and, (ii) the possibility of using gadolinium (Magnevist®) loaded-TSLnps (Gd-TSLnps) to increase magnetic resonance imaging (MRI) contrast in solid tumor. In this study, we developed and tested gemcitabine-loaded thermosensitive liposomal nanoparticles (Gem-TSLnps) and gadolinium-loaded thermosensitive liposomal nanoparticles (Gd-TSLnps) both in in-vitro and in-vivo. The TSLnps exhibited temperature-dependent release of Gem, at 40–42°C, 65% of Gem was released within 10 min, whereas < 23% Gem leakage occurred at 37°C after a period of 2 h. The pharmacokinetic parameters and tissue distribution of both Gem-TSLnps and Gd-TSLnps were significantly greater compared with free Gem and Gd, while Gem-TSLnps plasma clearance was reduced by 17-fold and that of Gd-TSLpns was decreased by 2-fold. Area under the plasma concentration time curve (AUC) of Gem-TSLnps (35.17± 0.04 μghr/mL) was significantly higher than that of free Gem (2.09 ± 0.01 μghr/mL) whereas, AUC of Gd-TSLnps was higher than free Gd by 3.9 fold high. TSLnps showed significant Gem accumulation in heated tumor relative to free Gem. Similar trend of increased Gd-TSLnps accumulation was observed in non-heated tumor compared to that of free Gd; however, no significant difference in MRI contrast enhancement between free Gd and Gd-TSLnps ex-vivo tumor images was observed. Despite Gem-TSLnps dose being half of free Gem dose, antitumor efficacy of Gem-TSLnps was comparable to that of free Gem(Gem-TSLnps 10 mg Gem/kg compared with free Gem 20 mg/kg). Overall, the findings suggest that TSLnps may be used to improve Gem delivery and enhance its antitumor activity. However, the formulation of Gd-TSLnp needs to be fully optimized to significantly enhance MRI contrast in tumor.