Antitumor effects of combined therapy of recombinant heat shock protein 70 and hyperthermia using magnetic nanoparticles in an experimental subcutaneous murine melanoma

Heat shock proteins (HSPs) are recognized as significant participants in cancer immunity. We previously reported that HSP70 expression following hyperthermia using magnetic nanoparticles induces antitumor immunity. In the present study, we examine whether the antitumor immunity induced by hyperthermia is enhanced by administration of recombinant HSP70 protein into the tumor in situ. Hyperthermia was conducted using our original magnetite cationic liposomes (MCLs), which have a positive surface charge and generate heat in an alternating magnetic field (AMF) due to hysteresis loss. MCLs and recombinant mouse HSP70 (rmHSP70) were injected into melanoma nodules in C57BL/6 mice, which were subjected to AMF for 30 min. Temperature within the tumor reached 43°C and was maintained by controlling the magnetic field intensity. The combined treatment strongly inhibited tumor growth over a 30-day period and complete regression of tumors was observed in 20% (2/10) of mice. It was also found that systemic antitumor immunity was induced in the cured mice. This study suggests that novel combined therapy using exogenous HSP70 and hyperthermia has great potential in cancer treatment.     

3D in silico study of magnetic fluid hyperthermia of breast tumor using Fe3O4 magnetic nanoparticles

Modeling and simulation of the temperature distribution, the mass concentration, and the heat transfer in the breast tissue are hot issues in magnetic fluid hyperthermia treatment of cancer. The breast tissue can be visualized as a porous matrix with saturated blood. In this paper, 3D in silico study of breast cancer hyperthermia using magnetic nanoparticles (MNPs) is conducted. The 3D FEM models are incorporated to investigate the infusion and backflow of nanofluid in the breast tumor, the diffusion of nanofluid, temperature distribution during the treatment, and prediction of the fraction of tumor necrosis while dealing with the thermal therapy. All the hyperthermia procedures are simulated and analyzed on COMSOL Multiphysics. The sensitivity of frequency and amplitude of the applied magnetic field (AMF) is investigated on the heating effect of the tumor. The mesh dependent solution of Penne's bioheat model is also analyzed. The simulated results demonstrate successful breast cancer treatment using MNPs with minimum side effects. Validation of current simulations results with experimental studies existing in literature advocates the success of our therapy. The increase in the amplitude and frequency of the AMF increases of the temperature in the tumor. The variation of mesh from coarser to finer increased the temperature through small fractions. We have also simulated the magnetic induction problem where the magnetic field is generated by current-carrying coil conductors induce heat in nearby breast tumors due to excitation of MNPs by magnetic flux. This research will aid treatment protocols and real-time clinical breast cancer treatments.     

Cancer immunotherapy based on intracellular hyperthermia using magnetite nanoparticles: a novel concept of “heat-controlled necrosis” with heat shock protein expression

Heat shock proteins (HSPs) are highly conserved proteins whose syntheses are induced by a variety of stresses, including heat stress. Since the expression of HSPs, including HSP70, protects cells from heat-induced apoptosis, HSP expression has been considered to be a complicating factor in hyperthermia. On the other hand, recent reports have shown the importance of HSPs, such as HSP70, HSP90 and glucose-regulated protein 96 (gp96), in immune reactions. If HSP expression induced by hyperthermia is involved in tumor immunity, novel cancer immunotherapy based on this novel concept can be developed. In such a strategy, a tumor-specific hyperthermia system, which can heat the local tumor region to the intended temperature without damaging normal tissue, would be highly advantageous. To achieve tumor-specific hyperthermia, we have developed an intracellular hyperthermia system using magnetite nanoparticles. This novel hyperthermia system can induce necrotic cell death via HSP expression, which induces antitumor immunity. In the present article, cancer immunology and immunotherapy based on hyperthermia, and HSP expression are reviewed and discussed. This article forms part of the Symposium in Writing "Thermal stress-related modulation of tumor cell physiology and immune responses", edited by Elfriede Noessner.     

调制磁性纳米颗粒提高磁热性能的研究

磁性纳米颗粒具有独特的磁学性质,即在外加交变磁场下因产生磁滞释放热量,使其在生物医学领域,特别是肿瘤磁热疗,获得了广泛应用.到目前为止,磁性纳米颗粒介导的磁热疗成为一种治疗癌症的有效手段,已进入临床三期实验.因此,针对磁性纳米颗粒本身,优化设计尺寸、形貌、组分和表面修饰来提高其磁热性能,进而减小临床应用中的颗粒浓度来最小化毒副作用的研究,对肿瘤治疗及生物医药研究具有十分重要的意义.本综述详述如何优化调制磁性纳米颗粒以提高其磁热性能,为高效、低毒的磁性纳米颗粒的设计提供了指导性的研究方向.     

Silver nanocrystals sensitize magnetic-nanoparticle-mediated thermo-induced killing of cancer cells

Magnetic nanoparticles (MNPs) can heat up tumor tissues and induce killing of cancer cells under external AC magnetic field. However, magnetic nanoparticles hyperthermia (MNPH) requires high concentration of MNPs that are injected into the tumor in order to obtain clinically needed thermal dose because of the complicated heat transfer in vivo and the limited heat quality of MNPs. To cut down the dose of MNPs and enhance the effect of this Nanotherapy, we prepared silver nanoparticles (AgNPs) with different sizes and investigated the effects of these AgNPs on cancer cells in MNPH treatment. It was found that AgNPs could enhance thermo-sensitivity of glioma cells and this effect was size dependent. AgNPs could induce cell cycles arrested in G(2)/M phase and enhanced the apoptosis rate of cancer cells after hyperthermia. In glioma bearing rats model, MNPH combined with AgNPs could enhance Bax expression in cancer cells. Our results suggested that AgNPs could be a potential thermo-sensitizer and could be further developed for the design of Ag nanostructure-based thermal seeds for MNPH therapy.     

纳米铁氧化物磁热疗相关机制研究进展

热疗作为继手术、放疗和化疗后的肿瘤治疗的重要方法之一,自其诞生之初便受到研究人员和产业部门的关注.磁热疗目前已经应用到前列腺癌、脑部肿瘤等临床实验或治疗中,并取得较好的疗效.本文主要介绍基于磁性纳米颗粒的磁热疗产热物理机制与影响因素,以及磁热的亚细胞水平生物学效应.     

Changes in muscle pH following hyperthermia

Considerable attention has been paid to the modification of intratumor pH in response to hyperthermia. It has been hypothesized that observed reductions in intralesional pH are involved in the ultimate response of tissue to hyperthermia treatment. Further, it has been shown that significant differences exist in hyperthermia-induced changes in blood flow between tumor and normal tissue in many systems. Changes in blood flow are hypothesized to be related to observed changes in pH. Since reduced blood flow is not observed in normal tissue under normal treatment conditions, changes in pH in normal tissue have not been considered significant in their response to hyperthermia treatment. However, this conclusion has not been verified or documented experimentally. The purpose of this study was to examine the distribution of pH in normal tissue (muscle) as a function of time following hyperthermia treatments which in the same animal system resulted in subcurative (TCD 10/30) or curative (TCD 90/30) tumor (mammary adenocarcinoma) responses. The observed distribution of pH in normal tissue was compared with that obtained in tumors under identical conditions. The results indicate that some post-treatment changes in muscle pH do occur following hyperthermia, but that these changes are small compared to those observed in tumors. More importantly, unlike the response observed in tumors, no hyperthermia dose dependency is observed in the muscle response. From these studies it can be concluded that changes in normal muscle pH are probably not associated with normal tissue response to hyperthermia.     

Radiosensitizing properties of magnetic hyperthermia mediated by superparamagnetic iron oxide nanoparticles (SPIONs) on human cutaneous melanoma cell lines

Melanoma is responsible for the majority of deaths related to skin cancer. Worryingly, prognoses show an increasing number of melanoma cases each year worldwide. Radiotherapy, which is a cornerstone of cancer treatment, has proved to be useful but insufficient in melanoma management due to exceptionally high radioresistance of melanoma cells. This problem could be overcome by superparamagnetic iron oxide nanoparticles (SPIONs) used as heat mediators in magnetic hyperthermia, which not only enhance radiosensitivity, but also enable precise targeting by exploitation of their magnetic properties.     

Analysis of the Distribution of Magnetic Fluid inside Tumors by a Giant Magnetoresistance Probe

Magnetic fluid hyperthermia (MFH) therapy uses the magnetic component of electromagnetic fields in the radiofrequency spectrum to couple energy to magnetic nanoparticles inside tumors. In MFH therapy, magnetic fluid is injected into tumors and an alternating current (AC) magnetic flux is applied to heat the magnetic fluid- filled tumor. If the temperature can be maintained at the therapeutic threshold of 42°C for 30 minutes or more, the tumor cells can be destroyed. Analyzing the distribution of the magnetic fluid injected into tumors prior to the heating step in MFH therapy is an essential criterion for homogenous heating of tumors, since a decision can then be taken on the strength and localization of the applied external AC magnetic flux density needed to destroy the tumor without affecting healthy cells. This paper proposes a methodology for analyzing the distribution of magnetic fluid in a tumor by a specifically designed giant magnetoresistance (GMR) probe prior to MFH heat treatment. Experimental results analyzing the distribution of magnetic fluid suggest that different magnetic fluid weight densities could be estimated inside a single tumor by the GMR probe.     

Heat shock protein 70 expression induces antitumor immunity during intracellular hyperthermia using magnetite nanoparticles

In this study we demonstrated that heat shock protein (HSP) 70 expression by hyperthermia induced antitumor immunity in the T-9 rat glioma. Our hyperthermic system using magnetic nanoparticles induced necrotic cell death that correlated with HSP70 expression. We purified the HSP70-peptide complexes from the tumor after hyperthermia to investigate whether HSP70 was involved in the antitumor immunity, and we found that in the F344 rats immunized with T-9-derived HSP70 the tumor growth of T-9 was significantly suppressed. Tumor rejection assay after hyperthermic treatment of implanted T-9 cells with incorporated magnetite cationic liposomes (MCL) was performed to investigate whether antitumor immunity was induced by release of HSP70 from the necrotic cells in the F344 rat. Tumor growth was strongly suppressed in the rats subjected to hyperthermia of implanted T-9 cells, and 50% of rats were protected from challenge with T-9 cells. Immunogenicity was enhanced when the HSP70-overexpressing T-9 cells were killed via necrosis in rats by hyperthermia, after which all rats were completely protected from challenge with T-9 cells. Our hyperthermic system produces vaccination with HSP70-peptide via necrotic tumor cell death in vivo, resulting in antitumor immunity. This phenomenon, which may be termed in situ vaccination, has important implications for the development of novel antitumor therapies.     

铁磁热籽加温治疗肿瘤的研究

热疗治疗肿瘤是应用各种致热源的热效应,将肿瘤加热至有效治疗温度范围并维持一定时间,以杀灭肿瘤细胞的一种方法。本文探讨了用于加温治疗肿瘤的铁磁热籽在治疗时的加热原理和自控温机制。与目前几种加温方式和测温方式的相比,得出铁磁热籽在肿瘤治疗中利用感应加温有效的克服了其它加温方式的缺点,并且利用居里点效应实现了自控温。因此,有着诱人的前景。     

基于超声驱动磁性纳米粒子的肿瘤细胞灭杀

磁性纳米粒子肿瘤热疗技术是目前国际上肿瘤研究的热点.本文提出了一种基于超声驱动磁性纳米粒子(UDMNP)运动进行肿瘤细胞灭杀的新技术,实现磁性纳米粒子的肿瘤治疗.系统研究了肝癌肿瘤细胞HepG2的治疗效果,在一定超声频率下,改变超声功率和超声作用时间,UDMNP具有明显灭杀效果.实验结果显示,较小超声功率下,肿瘤细胞损伤较小,随着超声功率增加,UDMNP对肿瘤细胞表现出明显的灭杀作用.同时,随着作用时间增加,同一超声功率驱动下UDMNP对细胞的灭杀效果也明显提高,光学显微镜观察到细胞形态发生明显变化.本文提出的UDMNP肿瘤细胞灭杀方法的显著优势是减少了化学毒性和有害辐射,是一种物理性机械损伤技术,对促进磁性纳米粒子的临床医学应用有重要意义.     

Cell Labeling and Targeting with Superparamagnetic Iron Oxide Nanoparticles

Targeted delivery of cells and therapeutic agents would benefit a wide range of biomedical applications by concentrating the therapeutic effect at the target site while minimizing deleterious effects to off-target sites. Magnetic cell targeting is an efficient, safe, and straightforward delivery technique. Superparamagnetic iron oxide nanoparticles (SPION) are biodegradable, biocompatible, and can be endocytosed into cells to render them responsive to magnetic fields. The synthesis process involves creating magnetite (Fe₃O₄) nanoparticles followed by high-speed emulsification to form a poly(lactic-co-glycolic acid) (PLGA) coating. The PLGA-magnetite SPIONs are approximately 120 nm in diameter including the approximately 10 nm diameter magnetite core. When placed in culture medium, SPIONs are naturally endocytosed by cells and stored as small clusters within cytoplasmic endosomes. These particles impart sufficient magnetic mass to the cells to allow for targeting within magnetic fields. Numerous cell sorting and targeting applications are enabled by rendering various cell types responsive to magnetic fields. SPIONs have a variety of other biomedical applications as well including use as a medical imaging contrast agent, targeted drug or gene delivery, diagnostic assays, and generation of local hyperthermia for tumor therapy or tissue soldering.     

Nanoparticles and nanothermia for malignant brain tumors,a suggestion of treatment for further investigations

The current treatment for brain tumors, such as glioblastoma multiforme (GBM), has not been developed enough yet in order to fully heal them. The main causes are the lack of specificity of the treatments, the difficulty of passage of drugs through the blood–brain barrier, heterogeneity and tumor aggressiveness, and widespread dissemination in the brain. The application of nanoparticles (Nps) have been a breakthrough for both diagnostic imaging and targeted therapies. There have been numerous studies with different types of Nps in brain tumors, but we have focused on thermosensitive liposomes, which are characterized by releasing the chemotherapeutic agent included within its lipophilic membranes through heat. Furthermore, increasing the temperature in brain tumors through hyperthermia has been proven therapeutically beneficial. Nanothermia or modulated-electro-hyperthermia (MEHT) is an improved technique that allows to create hot spots in nanorange at the membrane rafts, specifically in tumor cells, theoretically increasing the selectivity of the damage. In scientific records, experiments that combine both techniques (thermosensitive liposomes and nanothermia) have never been conducted. We propose a hypothesis for further research.     

Laser hyperthermia of tumors using gold nanoparticles monitored by optical coherence tomography and acoustic thermometry

Local laser hyperthermia of grafted RShM-5 tumors in mice with the use of plasmon resonant gold nanoparticles has been carried out. Accumulation of particles in the tumor was monitored in vivo noninvasively by optical coherence tomography. Thereby it was determined that the maximal content of nanoparticles in the tumor was reached within 5 h after intravenous administration, and laser hyperthermia was performed at this time. Monitoring the tumor temperature during the treatment by IR thermography and acoustic thermometry showed that the nanoparticles provided efficient temperature elevation inside the tumor as well as more selective heating. Local laser hyperthermia with gold nanoparticles, but not the laser exposure alone, substantially inhibited tumor growth in several days after a single session.     

Nano-assisted radiofrequency ablation of clinically extracted irregularly-shaped liver tumors

Radiofrequency ablation (RFA) for liver tumors is a minimally invasive procedure that uses electrical energy and heat to destroy cancer cells. One of the critical factors that impedes its successful outcome is the use of inappropriate radiofrequency levels that will not completely destroy the target tumor tissues, resulting in therapy failure. Additionally, the surrounding healthy tissues may suffer from serious damage due to excessive ablation. To address these challenges, this work proposes the employment of injected nanoparticles to thermally promote the ablation efficacy of conventional RFA. A three-dimensional finite difference analysis is employed to simulate the RFA treatment. Based on the data acquired from measured experiments, the simulation results have demonstrated close agreement with experimental data with a maximum discrepancy of within ±8.7%. Several types of nanoparticles were selected to evaluate their influences on liver tissue's thermal and electrical properties. We analysed the effects of nanoparticles on liver RFA via a tumor rending process incorporating several clinically-extracted tumor profiles and vascular systems. Simulations were conducted to explore the temperature difference responses between conventional RFA treatment and one with the inclusion of assisted nanoparticles on several irregularly-shaped tumors. Results have indicated that applying selected nanoparticles with high thermal conductivity and electrical conductivity on the targeted tissue zone promotes heating rate while sustaining a similar ablation zone that experiences lower maximum temperature when compared with the conventional RFA treatment. In sum, incorporating thermally-enhancing nanoparticles promotes heat transfer during the RFA treatment, resulting in improved ablation efficiency.     

Effect of nanoheat stimulation mediated by magnetic nanocomposite hydrogel on the osteogenic differentiation of mesenchymal stem cells

Hyperthermia has been considered as a promising healing treatment in bone regeneration. We designed a tissue engineering hydrogel based on magnetic nanoparticles to explore the characteristics of hyperthermia for osteogenic regeneration. This nanocomposite hydrogel was successfully fabricated by incorporating magnetic Fe₃O₄ nanoparticles into chitosan/polyethylene glycol (PEG) hydrogel, which showed excellent biocompatibility and were able to easily achieve increasing temperatures under an alternative magnetic field (AMF). With uniformly dispersed nanoparticles, the composite hydrogel resulted in high viability of mesenchymal stem cells (MSCs), and the elevated temperature contributed to the highest osteogenic differentiation ability compared with direct heat treatment applied under equal temperatures. Therefore, the nanoheat stimulation method using the magnetic nanocomposite hydrogel under an AMF may be considered as an alternative candidate in bone tissue engineering regenerative applications.     

Folate-conjugated iron oxide nanoparticles for solid tumor targeting as potential specific magnetic hyperthermia mediators: synthesis, physicochemical characterization, and in vitro experiments

New folate-conjugated superparamagnetic maghemite nanoparticles have been synthesized for the intracellular hyperthermia treatment of solid tumors. These ultradispersed nanosystems have been characterized for their physicochemical properties and tumor cell targeting ability, facilitated by surface modification with folic acid. Preliminary experiments of nanoparticles heating under the influence of an alternating magnetic field at 108 kHz have been also performed. The nanoparticle size, surface charge, and colloidal stability have been assessed in various conditions of ionic strength and pH. The ability of these folate "decorated" maghemite nanoparticles to recognize the folate receptor has been investigated both by surface plasmon resonance and in folate receptor expressing cell lines, using radiolabeled folic acid in competitive binding experiments. The specificity of nanoparticle cellular uptake has been further investigated by transmission electron microscopy after incubation of these nanoparticles in the presence of three cell lines with differing folate receptor expression levels. Qualitative and quantitative determinations of both folate nanoparticles and nontargeted control nanoparticles demonstrated a specific cell internalization of the folate superparamagnetic nanoparticles.     

用于肿瘤治疗的免疫检查点抑制剂相关预测生物标志物的研究进展

恶性肿瘤是严重威胁人类健康和社会发展的疾病。传统的肿瘤治疗方法如手术、放疗、化疗和靶向治疗等不能完全满足临床治疗的需求,新兴的免疫治疗成为了肿瘤治疗领域的研究热点。免疫检查点抑制剂(immune checkpoint inhibitors,ICIs)作为一种肿瘤免疫治疗方法,已获批用于治疗多种肿瘤,如肺癌、肝癌、胃癌和结直肠癌等。然而,ICIs在临床使用过程中,只有少数患者会出现持久反应,一些患者还会出现耐药和不良反应。因此,预测生物标志物的鉴定和开发对提高ICIs的治疗效果至关重要。肿瘤ICIs预测生物标志物主要包括肿瘤生物标志物、肿瘤微环境生物标志物、循环相关生物标志物、宿主环境生物标志物以及组合生物标志物等,对患者筛查、个体化治疗和预后评估具有重要意义。本文就肿瘤ICIs治疗预测生物标志物的前沿进展作一综述。