Mild Whole-body Hyperthermia Research Articles

Exploring and validating heating dynamics in a radio-frequency electromagnetic field-based resonant chamber for mouse hyperthermia research

ABSTRACT Mild whole-body hyperthermia has been shown to have anti-tumor effects through an immune-modulating mechanism. Before it is widely applied in the clinic, tremendous mechanistic research in animals is necessary to adhere to evidence-based principles. The radio frequency electromagnetic field (RF-EMF) based heating facility could be a good choice for hyperthermia treatment, but the heating characteristics of a facility, including structure design, electromagnetic and thermal dosimetry, and the biologic effects of hyperthermia, need to be well elucidated. Here, we reported the heating characteristic study on a resonant chamber (RC) excited by a 1800 MHz solid source. The EMF in the RC was stirred by 24 static reflectors, which resulted in the standard deviation of electric field intensity being below 3 dB in the EM homogeneity evaluation. For the exposure scenario, six free-moving mice were loaded into separate cases and exposed simultaneously in the RC. The EMF energy absorption and distribution in exposed mice were calculated with the 12-plane-waves method of numerical simulation. Different levels of core body temperature increment in exposed mice were achieved through regulation of the source output power. Overexpression of heat shock proteins (HSPs) was detected in the liver, lung and muscle, but not in the brain of the exposed mice. The levels of representative inflammatory cytokines in the serum, TNF-α and IL-10 increased post RC exposure. Based on the heating characteristic study and validation, the applied RC would be a qualified heating system for mild whole-body hyperthermia effect research in mice.

Nanoparticle Delivery in Prostate Tumors Implanted in Mice Facilitated by Either Local or Whole-Body Heating.

This work discusses in vivo experiments that were performed to evaluate whether local or whole-body heating to 40 °C reduced interstitial fluid pressures (IFPs) and enhanced nanoparticle delivery to subcutaneous PC3 human prostate cancer xenograft tumors in mice. After heating, 0.2 mL of a previously developed nanofluid containing gold nanoparticles (10 mg Au/mL) was injected via the tail vein. The induced whole-body hyperthermia led to increases in tumor and mouse body blood perfusion rates of more than 50% and 25%, respectively, while the increases were much smaller in the local heating group. In the whole-body hyperthermia groups, the IFP reduction from the baseline at the tumor center immediately after heating was found to be statistically significant when compared to the control group. The 1 h of local heating group showed IFP reductions at the tumor center, while the IFPs increased in the periphery of the tumor. The intratumoral gold nanoparticle accumulation was quantified using inductively coupled plasma mass spectrometry (ICP-MS). Compared to the control group, 1 h or 4 h of experiencing whole-body hyperthermia resulted in an average increase of 51% or 67% in the gold deposition in tumors, respectively. In the 1 h of local heating group, the increase in the gold deposition was 34%. Our results suggest that 1 h of mild whole-body hyperthermia may be a cost-effective and readily implementable strategy for facilitating nanoparticle delivery to PC3 tumors in mice.

Mild Whole-Body Hyperthermia-Induced Interstitial Fluid Pressure Reduction and Enhanced Nanoparticle Delivery to PC3 Tumors: In Vivo Studies and Micro-Computed Tomography Analyses

Abstract In this study, we performed in vivo experiments on mice to evaluate whether whole-body hyperthermia enhances nanoparticle delivery to PC3 (prostatic cancer) tumors. PC3 xenograft tumors in immunodeficient mice were used in this study. The mice in the experimental group were subjected to whole-body hyperthermia by maintaining their body temperatures at 39–40 °C for 1 h. Interstitial fluid pressures (IFPs) in tumors were measured before heating, immediately after, and at 2 and 24 h postheating in both the experimental group and in a control group (without heating). A total of 0.2 ml of a newly developed nanofluid containing gold nanoparticles (AuNPs) was delivered via the tail vein in both groups. The micro-computed tomography (microCT) scanned images of the resected tumors were analyzed to visualize the nanoparticle distribution in the tumors and to quantify the total amount of nanoparticles delivered to the tumors. Statistically significant IFP reductions of 45% right after heating, 47% 2 h after heating, and 52% 24 h after heating were observed in the experimental group. Analyses of microCT scans of the resected tumors illustrated that nanoparticles were more concentrated near the tumor periphery rather than at the tumor center. The 1-h whole-body hyperthermia treatment resulted in more nanoparticles present in the tumor central region than that in the control group. The mass index calculated from the microCT scans suggested overall 42% more nanoparticle delivery in the experimental group than that in the control group. We conclude that 1-h mild whole-body hyperthermia leads to sustained reduction in tumoral IFPs and significantly increases the total amount of targeted gold nanoparticle deposition in PC3 tumors. The present study suggests that mild whole-body hyperthermia is a promising approach for enhancing targeted drug delivery to tumors.

Abstract 3517: Use of a novel synthetic biomaterial to induce mild whole body hyperthermia for the treatment of cancer in a preclinical model

Abstract Hyperthermia is currently being investigated as an alternative form or cancer therapy. Numerous basic and pre-clinical published reports have shown the antitumor effects of hyperthermia in various cancer models. High temperatures, low duration (heat shock) will have a direct killing effect on exposed cells. The limitation to this approach is the restriction of tumor location and associated side effects. Low temperature, high duration whole body hyperthermia (WBH) is generally considered to be the least toxic but requires long exposures that are generally uncomfortable or inconvenient to the patients. In the present study, we show the efficacy of a synthetic far-infrared emitting biomaterial to induce and evaluate its therapeutic potential when used alone or in combination with chemotherapy. We used BioRubber (BR, Yamamoto Bio-Technology Inc., Anaheim, CA), a state of the art biomaterial that emits far infrared radiation in the 4-25 μm spectral ranges. To determine the efficacy to induce mild whole body hyperthermia, athymic nude mice were house in BR lined cages. Core body temperatures of mice housed in BR-lined cages were significantly higher than mice housed in unlined cages and were maintained up to 2 weeks during continuous exposure (37.70oC vs. 36.75oC, p=0.038, respectively.). To determine the antitumor effects of WBH, KU7/GFP-bearing nude mice were housed in cages lined with BR for 28 days. Non-significant tumor growth inhibition was observed in tumors of mice housed in BR. Histological and immunohistochemical analysis revealed increased granulocyte activity in tumors of BR-exposed mice. Additionally, increased levels of C-GSF, GM-CSF, TNFα and IL-12p70 corresponded to exposure to WBH. To determine the long term safety and efficacy of mild WBH and chemotherapy in deep tumors, we carried out a survival study using immunodeficient mice orthotopically inoculated with KU7/GFP cells and treated doxorubicin (Dox) alone or in combination with BR. Although no treatment efficacy was observed in mice treated with BR with regards to tumor size (tumor size according to the expression of GFP was 350.5, 309.7, 357.4, 257.3 for control, WBH, Dox and WBH/Dox groups, respectively), survival was improved for mice exposed to BR. Survival rates were 50% (5/10), 70% (7/10), 10% (1/10) and 50% (5/10), for control, WBH, Dox and WBH/Dox groups, respectively. It is unclear if mild WBH has a direct antitumor effect; however, it appears that BR-induced mild WBH may be capable of inducing immuno-stimulatory that may improve survival in a preclinical model. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 3517. doi:1538-7445.AM2012-3517

The effect of mild whole-body hyperthermia on systemic levels of TNF-alpha, IL-1beta, and IL-6 in patients with ankylosing spondylitis

Serial mild whole-body hyperthermia is a widely used balneotherapy modality for clinically inactive ankylosing spondylitis (AS) in rehabilitative medicine. Thus far, the mechanisms of its favorable influence on the symptoms of AS are not completely understood. We therefore analyzed the effect of mild whole-body hyperthermia on the systemic levels of pivotal proinflammatory cytokines. Twelve male subjects with AS and 12 healthy control subjects received nine cycles of whole-body hyperthermia (target body core temperature, 38.5 degrees C; duration, 50 min). Serum samples were taken at the beginning of the last cycle and at 1, 6, and 24 h for measurement of tumor necrosis factor alpha, interleukin 1beta and interleukin 6. Significant differences of cytokine levels were found between both groups. In AS patients, hyperthermia caused a significant reduction of all cytokines by 40-50%. Thus, serial mild whole-body hyperthermia in AS results in heat-induced changes of the proinflammatory cytokine network.

Effect of whole body hyperthermia (39°C, 1 h) on radiation-induced apoptosis in Swiss mice

Mild whole body hyperthermia (WBH) treatment when given prior to radiation exposure is known to protect mice against radiation-induced hemopoietic death. This radioprotective effect seems to be mediated through WBH-induced cytokines and growth factors. Exposure to total body irradiation (TBI) also induces cell death by apoptosis in animal cells. The present studies were therefore carried out to investigate whether WBH pretreatment could protect mice against radiation-induced apoptotic death. The extent of apoptosis in bone marrow cells derived from mice at different time intervals after WBH, TBI and whole body hyperthermia treatment given 20 h prior to total body irradiation (WBH+TBI) treatments was studied by three independent methods namely DNA ladder assay, terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end labeling assay and caspase-3 assay. The studies have revealed that the mild WBH treatment (39°C, 1 h) when given 20 h prior to TBI (8 Gy) results in reduction in TBI-induced apoptosis. The results imply that WBH-induced impairment of apoptosis may have some role in WBH-induced radioprotection in Swiss mice.

Heat preconditioning prevents oxidative stress-induced damage in the intestine and lung following surgical manipulation.

The intestine is increasingly recognized as a primary effector of distant organ damage, such as lung, following abdominal surgery. Surgical manipulation of the intestine generates oxygen free radicals resulting in mucosal damage. Heat preconditioning has been proposed to prevent various stress-induced alterations in cells and tissues, including oxidative stress. This study examined the effect of heat preconditioning on oxidative stress-induced damage to the intestine and lung, following surgical manipulation. Control rats and rats pretreated with heat were subjected to surgical manipulation by opening the abdominal wall and handling the intestine as done during laparotomy. Intestine and lung were assessed for damage by histology and markers of oxidative stress. Surgical manipulation resulted in ultrastructural changes in the intestine. Biochemical alterations in the enterocytes were evident, with increased xanthine oxidase activity resulting in production of superoxide anion and with a decrease in antioxidant status. Gut manipulation also resulted in neutrophil infiltration and oxidative stress in the lung as assessed by histology, myeloperoxidase activity, lipid peroxidation and antioxidant status. Heat conditioning before surgical manipulation had a protective effect against this intestinal and lung damage. This study suggests that mild whole-body hyperthermia before surgery might offer protection from postoperative complications.

Teratogenic effects of mild heat stress during mouse embryogenesis: effect of Trp53.

Hyperthermia can be teratogenic in fetal mice exposed during organogenesis, an effect considered to be due to heat-induced apoptosis of cells in the developing organs. We exposed pregnant mice carrying Trp53(+/+), Trp53(+/-) and Trp53(-/-) fetuses to mild whole-body hyperthermia that raised their core temperature to 40.5 degrees C for 60 min on either day 10 or 11 of gestation. On day 18 of gestation, the fetuses were removed from control and hyperthermia-treated mice and genotyped, and tail length was measured. Limb digits were examined for abnormalities. Tail length in unheated control fetuses was influenced by Trp53 status. A complete lack of functional Trp53 (Trp53(-/-)) but not partial lack of function (Trp53(+/-)) resulted in shorter tails compared to Trp53(+/+) fetuses, indicating a role for Trp53 in the regulation of tail lengthening in mouse fetuses. In all three genotypes, hyperthermia on gestation day 10 resulted in tails shorter than unheated controls, and hyperthermia on day 11 resulted in tails longer than controls. There was no effect on limb digit abnormalities. The data suggest that Trp53-dependent or independent apoptosis may not be directly involved in heat-induced teratogenesis, but that the primary teratogenic effect of heat results from the disruption of another tail length-regulating process that is independent of Trp53. However, the nature of the teratogenic outcome of that disruption depends on the gestation time. The ability of Trp53 to additionally regulate the tail lengthening process was also sensitive to the effects of heat, but that sensitivity again depended on the time of the heat stress during gestation.

Effect of mild whole body hyperthermia on cytotoxic action of N-methyl- N′-nitro- N-nitrosoguanidine in Swiss mice

Studies were carried out to ascertain the efficacy of mild whole body hyperthermia (WBH) as a modifier of N-methyl- N′-nitro- N-nitrosoguanidine (MNNG) cytotoxicity in mice. Adult Swiss male mice, 6–8 weeks old, weighing about 25 g were exposed to mild WBH (39°C, 1 h) in a precision temperature controlled environmental chamber maintained at 50–60% relative humidity. Twenty-four hours after treatment, animals were administered with different doses of MNNG either by intraperitoneal (i.p.) injections or by feeding through drinking water and were monitored for survival. The studies revealed that the exposure of animals to mild WBH, 24 h prior to MNNG administration results in an increase in survival and recovery in mean body weight compared with those administered with MNNG only. This suggests that prior WBH treatment can effectively reduce the MNNG cytotoxicity in mice.

A pilot study of melphalan, tumor necrosis factor-alpha and 41.8 degrees C whole-body hyperthermia.

To evaluate the feasibilitv of sequencing (based on preclinical modeling) tumor necrosis factor-a (TNF) at two dose levels with melphalan (L-PAM) and 41.8 C whole-body hyperthermia (WBH) for 60 min. Nine patients with refractory cancer were treated from October 1995 to June 1997. The study encompassed a total of 20 trimodality treatment courses. Three patients were treated at TNF dose level I (50 microg/m2) and six patients were treated at TNF dose level II (100 microg/m2). TNF was delivered as a 24-h intravenous infusion, 48 h prior to the combination of L-PAM and WBH; L-PAM was given over 10 min at target temperature at a dose of 17.5 mg/ m2 based on a previous phase I WBH/L-PAM trial. WBH was administered with an Aquatherm radiant heat device. Myelosuppression was the major toxicity associated with therapy, but there were no instances of bleeding or neutropenic fevers. Grade 3 thrombocytopenia was seen with 15% of treatments. Regarding absolute neutrophil count, 15% of treatments were associated with grade 3 toxicity, and 45% with grade 4 toxicity, and regarding white blood cell count, 50% of treatments were associated with grade 3 toxicity and 10% with grade 4 toxicity. The myelosuppression observed was equivalent to that seen in our earlier phase I study of WBH and L-PAM (without TNF). Only mild toxicities (grade 1 or 2) were associated with TNF; these were seen with <25% of treatments and included nausea, vomiting, diarrhea, fevers, and headache. There were no instances of hypotension. There was no relationship between toxicities observed and the two TNF dose levels. Mild WBH toxicities were seen with less than 15% of treatments; these included nausea, vomiting, and herpes simplex I. Responses included two complete remissions (malignant melanoma, TNF dose level I; breast cancer, TNF dose level II), and two disease stabilizations (both malignant melanoma, TNF dose level I). We conclude that the combination of TNF, L-PAM, and WBH is well tolerated at the dose levels studied. The clinical results justify further clinical investigation for this trimodality treatment approach.

Characterization of mild whole-body hyperthermia protocols using human breast, ovarian, and colon tumors grown in severe combined immunodeficient mice.

We have shown that one treatment of fever-like whole body hyperthermia (WBH) on mice bearing human breast tumors results in a tumor growth delay. Our goal was to repeat this study in mice bearing human ovarian or colon tumors. We further evaluated this WBH protocol by performing multiple and interrupted WBH treatments. Human tumors were grown in severe combined immunodeficient (SCID) mice. For WBH, core body temperatures were maintained at 39.8+/-0.2 degrees C for 6-8 hours. Multiple treatments were given 6-7 days apart. Interrupted WBH consisted of three 2-hour heatings, 15 minutes apart. Tumor growth time (TGT) was the number of days to grow 1.5 or 2 times in volume. For WBH-treated ovarian tumors, TGT was 12+/-1.2d, compared with 5.0+/-0.1d for untreated mice (P < 0.05). For colon tumors with one WBH treatment TGT was 4.4+/-1.1d. Two and three treatments had TGTs of 9+/-2.3d and 8+/-1.6d. For the untreated tumors, TGT was 2+/-0.7d (P < 0.01 for one, two, and three treatments). Histological examination indicated that one and two treatments were associated with cellular damage within the tumors. With a slower growing colon tumor, the TGT was 24+/-3.3d with three WBH treatments, compared with 14+/-1.8d for controls (P < 0.01). The TGT of breast tumors treated with interrupted WBH was not significantly different than the noninterrupted, with TGT of 7.3+/-0.8d and 6.2+/-1.0d, respectively. These data illustrate that WBH causes a tumor growth delay in mice bearing human ovarian and colon tumors. This response is enhanced with a second treatment of WBH. Interrupted and noninterrupted WBH give comparable anti-tumor results. We will continue to evaluate WBH in various animal models to optimize its potential for clinical administration and maximize the anti-tumor response.

Characterization of mild whole-body hyperthermia protocols using human breast, ovarian, and colon tumors grown in severe combined immunodeficient mice

We have shown that one treatment of fever-like whole body hyperthermia (WBH) on mice bearing human breast tumors results in a tumor growth delay. Our goal was to repeat this study in mice bearing human ovarian or colon tumors. We further evaluated this WBH protocol by performing multiple and interrupted WBH treatments.Human tumors were grown in severe combined immunodeficient (SCID) mice. For WBH, core body temperatures were maintained at 39.8+/-0.2 degrees C for 6-8 hours. Multiple treatments were given 6-7 days apart. Interrupted WBH consisted of three 2-hour heatings, 15 minutes apart. Tumor growth time (TGT) was the number of days to grow 1.5 or 2 times in volume.For WBH-treated ovarian tumors, TGT was 12+/-1.2d, compared with 5.0+/-0.1d for untreated mice (P < 0.05). For colon tumors with one WBH treatment TGT was 4.4+/-1.1d. Two and three treatments had TGTs of 9+/-2.3d and 8+/-1.6d. For the untreated tumors, TGT was 2+/-0.7d (P < 0.01 for one, two, and three treatments). Histological examination indicated that one and two treatments were associated with cellular damage within the tumors. With a slower growing colon tumor, the TGT was 24+/-3.3d with three WBH treatments, compared with 14+/-1.8d for controls (P < 0.01). The TGT of breast tumors treated with interrupted WBH was not significantly different than the noninterrupted, with TGT of 7.3+/-0.8d and 6.2+/-1.0d, respectively.These data illustrate that WBH causes a tumor growth delay in mice bearing human ovarian and colon tumors. This response is enhanced with a second treatment of WBH. Interrupted and noninterrupted WBH give comparable anti-tumor results. We will continue to evaluate WBH in various animal models to optimize its potential for clinical administration and maximize the anti-tumor response.

Effect of mild hyperthermia on the ischemic infarct volume after middle cerebral artery occlusion in the rat

We investigated the effect of mild whole-body hyperthermia (40 degrees C) on a permanent middle cerebral artery occlusion (MCAo) model in Fisher rats by subjecting them to MCAo under the following conditions: (1) normothermia (n = 20); (2) hyperthermia (n = 14) before (1 hour), during, and after (1 hour) MCAo; and (3) post-MCAo hyperthermia (n = 14) for 1 hour. We measured brain and body temperatures during the experiment using micro-thermocouples and blood-brain-barrier (BBB) permeability using Evans blue staining of the brain. We measured the volume of the infarcted brain tissue 4 days after MCAo. We detected no differences in BBB permeability among three groups. The volume of infarcted tissue was significantly greater (p less than 0.05) for the two groups of hyperthermic animals than the normothermic animals. Our data suggest that mild hyperthermia, both during and after induction of ischemia, has a detrimental effect on the ischemic infarct volume in this model.

Effect of mild hyperthermia on recovery of metabolic function after global cerebral ischemia in cats.

We investigated the effect of mild whole-body hyperthermia before and after 16 minutes of global cerebral ischemia on metabolic recovery during recirculation in cats using in vivo phosphorus-31 nuclear magnetic resonance spectroscopy. Hyperthermia (temperature 40.6 +/- 0.2 degrees C) was induced greater than or equal to 1 hour before ischemia and was maintained during 1.5-2 hours of recirculation in nine cats; four cats were subjected to hyperthermia without cerebral ischemia, six to hyperthermia during recirculation (after return of intracellular pH to preischemic values), and 14 to normothermic ischemia and recirculation. Our data indicate that preischemic hyperthermia results in an intracellular cerebral pH during recirculation significantly lower than that in normothermic cats. In hyperthermic cats beta-ATP and phosphocreatine (PCr) concentrations and the ratio of PCr to inorganic phosphate failed to return to preischemic levels during recirculation in contrast to normothermic cats. Hyperthermia without ischemia and hyperthermia during recirculation had no significant effect on intracellular pH. Thus, preischemic hyperthermia has a detrimental effect on metabolic recovery after transient global cerebral ischemia.