In vitro effect of focused ultrasound or thermal stress on HSP70 expression and cell viability in three tumor cell lines

Pulsed focused ultrasound alters the proteomic profile of the tumor microenvironment in a syngeneic mouse model of glioblastoma

PURPOSE

Glioblastoma (GBM), a lethal primary adult malignancy, is difficult to treat because of the restrictive nature of the blood-brain barrier (BBB), blood-tumor barrier (BTB), and the immunosuppressive tumor microenvironment (TME). Since pulsed focused ultrasound (pFUS) is currently used to improve therapeutic deliveries across these barriers, this study aims to characterize the impact of pFUS on the TME proteomics upon opening the BBB and BTB.

METHODS

We utilized MRI-guided, pFUS with ultrasound contrast microbubbles (termed 'pFUS' herein) to selectively and transiently open the BBB and BTB investigating proteomic modifications in the TME. Utilizing an orthotopically-allografted mouse GL26 GBM model (Ccr2RFP/wt - Cx3cr1GFP/wt), pFUS's effect on glioma proteomics was evaluated using a Luminex 48-plex assay.

RESULTS

pFUS treated tumors exhibited increases in pro-inflammatory cytokines, chemokines, and trophic factors (CCTFs). Proteomic changes in tumors tend to peak at 24 h after single pFUS session (1x), with levels then plateauing or declining over the subsequent 24 h. Tumors receiving three pFUS sessions (3x) showed elevated CCTFs levels peaking as early as 6 h after the third session.

CONCLUSIONS

pFUS together with microbubbles induces a sterile inflammatory response in the TME of a mouse GBM tumor. Moreover, this proinflammatory shift can be sustained and perhaps primed for more rapid responses upon multiple sessions of pFUS. These findings raise the intriguing potential that pFUS-induced BBB and BTB opening may not only be effective in facilitating the therapeutic agent delivery, but also be harnessed to modify the TME to assist immunotherapies in overcoming immune evasion in GBM.

Analyzing Gene Expression After Administration of Low-Intensity Therapeutic Ultrasound in Human Islet Cells

OBJECTIVES

Diabetes mellitus is a complex heterogenous metabolic disease that significantly affects the world population. Although many treatments exist, including medications such as metformin, sulfonylureas, and glucagon-like peptide-1 (GLP) receptor agonist, there is growing interest in finding alternative methods to noninvasively treat this disease. It has been previously shown that low-intensity ultrasound stimulation of pancreatic β-cells in mice can elicit insulin secretion as a potential treatment for this disease. This is desirable as therapeutic ultrasound has the ability to induce bioeffects while selectively focusing deep within tissues, allowing for modulation of hormone secretion in the pancreas to mitigate insufficient levels of insulin.

METHODS

Exactly 800 kHz ultrasound with intensity 0.5 W/cm2 was administered 5 minutes continuously, that is, 100% duty cycle, to donor pancreatic human islets, followed by 1 hour incubation and RT-qPCR to assess the effect of ultrasound stimulation on gene expression. The genes were insulin (INS), glucagon (Glu), amylin (Amy), and binding immunoglobulin protein (BiP). Nine donor pancreatic human islets were used to assess insulin and glucagon secretion, while eight samples were used for amylin and BiP. Fold change (FC) was calculated to analyze the effect of ultrasound stimulation on the gene expression of the donor islet cells. High-glucose and thapsigargin-treated islets were utilized as positive controls. Cell viability testing was done using a Trypan Blue Exclusion Test.

RESULTS

Ultrasound stimulation did not cause a statistically significant upregulation in any of the tested genes (INS FC = 1.15, P-value = .5692; Glu FC = 1.60, P-value = .2231; Amy FC, P-value = .2863; BiP FC = 2.68, P-value = .3907).

CONCLUSIONS

The results of this study show that the proposed ultrasound treatment parameters do not appear to significantly affect gene expression of any gene tested.

Immunomodulation and targeted drug delivery with high intensity focused ultrasound (HIFU): Principles and mechanisms

High intensity focused ultrasound (HIFU) is a non-invasive and non-ionizing sonic energy-based therapeutic technology for inducing thermal and non-thermal effects in tissues. Depending on the parameters, HIFU can ablate tissues by heating them to >55 °C to induce denaturation and coagulative necrosis, improve radio- and chemo-sensitizations and local drug delivery from nanoparticles at moderate hyperthermia (~41-43 °C), and mechanically fragment cells using acoustic cavitation (also known as histotripsy). HIFU has already emerged as an attractive modality for treating human prostate cancer, veterinary cancers, and neuromodulation. Herein, we comprehensively review the role of HIFU in enhancing drug delivery and immunotherapy in soft and calcified tissues. Specifically, the ability of HIFU to improve adjuvant treatments from various classes of drugs is described. These crucial insights highlight the opportunities and challenges of HIFU technology and its potential to support new clinical trials and translation to patients.

Quantitative evaluation of the dynamic activity of HeLa cells in different viability states using dynamic full-field optical coherence microscopy

Dynamic full-field optical coherence microscopy (DFFOCM) was used to characterize the intracellular dynamic activities and cytoskeleton of HeLa cells in different viability states. HeLa cell samples were continuously monitored for 24 hours and compared with histological examination to confirm the cell viability states. The averaged mean frequency and magnitude observed in healthy cells were 4.79±0.5 Hz and 2.44±1.06, respectively. In dead cells, the averaged mean frequency was shifted to 8.57±0.71 Hz, whereas the magnitude was significantly decreased to 0.53±0.25. This cell dynamic activity analysis using DFFOCM is expected to replace conventional time-consuming and biopsies-required histological or biochemical methods.

Hyperthermia and Tumor Immunity

Thermal ablation is a cornerstone in the management of cancer patients. Typically, ablation procedures are performed for patients with a solitary or oligometastatic disease with the intention of eradicating all sites of the disease. Ablation has traditionally played a less prominent role for patients with a widely metastatic disease. For such patients, attempting to treat numerous sites of disease compounds potential risks without a clear clinical benefit and, as such, a compelling justification for performing an intervention that is unlikely to alter a patient's clinical trajectory is uncommon. However, the discovery of immune checkpoints and the development of immune checkpoint inhibitors have brought a new perspective to the relevance of local cancer therapies such as ablation for patients with a metastatic disease. It is becoming increasingly apparent that local cancer therapies can have systemic immune effects. Thus, in the new perspective of cancer care centered upon immunologic principles, there is a strong interest in exploring the utility of ablation for patients with a metastatic disease for its immunologic implications. In this review, we summarize the unmet clinical need for adjuvant interventions such as ablation to broaden the impact of systemic immunotherapies. We additionally highlight the extant preclinical and clinical data for the immunogenicity of common thermal ablation modalities.

Focused Ultrasound for Immunomodulation of the Tumor Microenvironment

Focused ultrasound (FUS) has recently emerged as a modulator of the tumor microenvironment, paving the way for FUS to become a safe yet formidable cancer treatment option. Several mechanisms have been proposed for the role of FUS in facilitating immune responses and overcoming drug delivery barriers. However, with the wide variety of FUS parameters used in diverse tumor types, it is challenging to pinpoint FUS specifications that may elicit the desired antitumor response. To clarify FUS bioeffects, we summarize four mechanisms of action, including thermal ablation, hyperthermia/thermal stress, mechanical perturbation, and histotripsy, each inducing unique vascular and immunological effects. Notable tumor responses to FUS include enhanced vascular permeability, increased T cell infiltration, and tumor growth suppression. In this review, we have categorized and reviewed recent methods of using therapeutic ultrasound to elicit an antitumor immune response with examples that reveal specific solutions and challenges in this new research area.

Combination of thermally ablative focused ultrasound with gemcitabine controls breast cancer via adaptive immunity

Background

Triple-negative breast cancer (TNBC) remains recalcitrant to most targeted therapy approaches. However, recent clinical studies suggest that inducing tumor damage can render TNBC responsive to immunotherapy. We therefore tested a strategy for immune sensitization of murine TNBC (4T1 tumors) through combination of focused ultrasound (FUS) thermal ablation and a chemotherapy, gemcitabine (GEM), known to attenuate myeloid-derived suppressor cells (MDSCs).

Methods

We applied a sparse-scan thermally ablative FUS regimen at the tumor site in combination with systemically administered GEM. We used flow cytometry analysis to investigate the roles of monotherapy and combinatorial therapy in mediating local and systemic immunity. We also tested this combination in Rag1^−/− mice or T cell-depleted wild-type mice to determine the essentiality of adaptive immunity. Further, we layered Programmed cell death protein 1 (PD-1) blockade onto this combination to evaluate its impact on tumor outgrowth and survival.

Results

The immune-modulatory effect of FUS monotherapy was insufficient to promote a robust T cell response against 4T1, consistent with the dominant MDSC-driven immunosuppression evident in this model. The combination of FUS+GEM significantly constrained primary TNBC tumor outgrowth and extended overall survival of mice. Tumor control correlated with increased circulating antigen-experienced T cells and was entirely dependent on T cell-mediated immunity. The ability of FUS+GEM to control primary tumor outgrowth was moderately enhanced by either neoadjuvant or adjuvant treatment with anti-PD-1.

Conclusion

Thermally ablative FUS in combination with GEM restricts primary tumor outgrowth, improves survival and enhances immunogenicity in a murine metastatic TNBC model. This treatment strategy promises a novel option for potentiating the role of FUS in immunotherapy of metastatic TNBC and is worthy of future clinical evaluation.

Trial registration numbers

NCT03237572 and NCT04116320.

High-Intensity Focused Ultrasound (HIFU) Triggers Immune Sensitization of Refractory Murine Neuroblastoma to Checkpoint Inhibitor Therapy

PURPOSE

Immunotherapy promises unprecedented benefits to patients with cancer. However, the majority of cancer types, including high-risk neuroblastoma, remain immunologically unresponsive. High-intensity focused ultrasound (HIFU) is a noninvasive technique that can mechanically fractionate tumors, transforming immunologically "cold" tumors into responsive "hot" tumors.

EXPERIMENTAL DESIGN

We treated <2% of tumor volume in previously unresponsive, large, refractory murine neuroblastoma tumors with mechanical HIFU and assessed systemic immune response using flow cytometry, ELISA, and gene sequencing. In addition, we combined this treatment with αCTLA-4 and αPD-L1 to study its effect on the immune response and long-term survival.

RESULTS

Combining HIFU with αCTLA-4 and αPD-L1 significantly enhances antitumor response, improving survival from 0% to 62.5%. HIFU alone causes upregulation of splenic and lymph node NK cells and circulating IL2, IFNγ, and DAMPs, whereas immune regulators like CD4+Foxp3+, IL10, and VEGF-A are significantly reduced. HIFU combined with checkpoint inhibitors induced significant increases in intratumoral CD4+, CD8α+, and CD8α+CD11c+ cells, CD11c+ in regional lymph nodes, and decrease in circulating IL10 compared with untreated group. We also report significant abscopal effect following unilateral treatment of mice with large, established bilateral tumors using HIFU and checkpoint inhibitors compared with tumors treated with HIFU or checkpoint inhibitors alone (61.1% survival, P < 0.0001). This combination treatment significantly also induces CD4+CD44+hiCD62L+low and CD8α+CD44+hiCD62L+low population and is adoptively transferable, imparting immunity, slowing subsequent de novo tumor engraftment.

CONCLUSIONS

Mechanical fractionation of tumors using HIFU can effectively induce immune sensitization in a previously unresponsive murine neuroblastoma model and promises a novel yet efficacious immunoadjuvant modality to overcome therapeutic resistance.

Possible involvement of HSP70 in pancreatic cancer cell proliferation after heat exposure and impact on RFA postoperative patient prognosis

Purpose

As an alleviative treatment measured in patients with unresectable advanced pancreatic cancer, radiofrequency ablation (RFA) needed more clinical data to prove its advantages and to explore limitations in its utilization. This study was determined to observe the efficacy of RFA, and to explore its impact on perioperative periphery carcinoma as well as the normal pancreatic tissues.

Methods

Clinical data of 32 patients with pancreatic cancer accepted RFA surgery were collected. Followed up patients' pain degree and the changes in serum tumor markers CA19-9 and CA 242 before and after surgery. Ex vivo, gave human pancreatic cancer cell line PANC-1 heat treatment to simulate the heat exposure condition periphery carcinoma was experienced during RFA surgery, and to observe the proliferation rate and HSP70 expression change compared with control group.

Results

Of the 32 patients, 1 died of upper gastrointestinal hemorrhage, and 29 survived for more than 5 months, 2 of which for more than 16 months. The average CA19-9 and CA 242 levels of the patients were significantly decreased in 3 months after surgery (t = 9.873, 5.978, P < 0.001). During in vitro experiments, the proliferation rate of PANC-1 cells after heating was significantly increased, accompanied with the increased HSP70 expression. The addition of HSP70 inhibitor can inhibit the rise of proliferation after heat therapy.

Conclusion

Utilizing RFA treat patients with unresectable advanced pancreatic cancer, could effectively relieve the pain, decline jaundice, and deduce tumor marker levels significantly. However, it failed to extend the long-term survival rate of the patients significantly. This study found that a higher proliferative rate accompanied with a higher HSP70 expression level were observed on in vitro cultured pancreatic carcinoma cells after heat treatment, which could be altered by HSP70 inhibitor. And these findings indicated that the heat exposure might impact periphery carcinoma during RFA surgery and HSP70 might play an important role in patients' prognosis.

Postablation Immune Microenvironment: Synergy between Interventional Oncology and Immuno-oncology

Current tumor thermal ablation techniques rely on extreme temperatures to induce irreversible cellular injury and coagulative tissue necrosis. Ablation-induced cellular injury or death releases cancer neoantigens and activates the cancer-immunity cycle, potentially generating tumor-specific immune effectors. However, multiple negative regulatory modulators exist at each step of the cycle, mitigating meaningful and therapeutic anticancer effect provided by the immune system. Recent studies have focused on the introduction and testing of adjuvant immunotherapy combined with ablation to synergistically shift the equilibrium out of inhibitory immune modulation. This article reviews the immune microenvironment in relation to image-guided ablation techniques and discusses current and upcoming novel strategies to take advantage of antitumor immunity.

Boiling Histotripsy-induced Partial Mechanical Ablation Modulates Tumour Microenvironment by Promoting Immunogenic Cell Death of Cancers

Boiling histotripsy is a promising non-invasive High-Intensity Focused Ultrasound (HIFU) technique that employs HIFU mechanical effects to fractionate solid tumours without causing any significant thermal damage. It has been suggested that boiling histotripsy may induce a strong immune response due to the absence of denatured antigenic protein at the HIFU focus. The underlying immunological mechanisms of this technique are, however, poorly understood. In this study, we demonstrated the feasibility of using boiling histotripsy to mechanically fractionate human breast adenocarcinoma cells (MDA-MB-231) and the potential immunological effects induced by boiling histotripsy, for the first time. Our results showed that mechanical stresses produced by boiling histotripsy promote immunogenic cell death of cancer cells via TNF-induced necrosis signaling pathway. This immunogenic cell death significantly increases secretions of damage-associated molecular patterns (CRT, HSP70, HMGB-1), pro-inflammatory cytokines (IFN-γ, IL-1α, IL-1β, IL-18) and chemokines (IL-8) which are related to M1 macrophage activation. Furthermore, the levels of these signaling proteins increase with the degree of mechanical damage induced by boiling histotripsy. Together, the results presented can suggest that boiling histotripsy could be a potential therapeutic approach for not only mechanically destroying solid tumours (e.g., breast cancer) but also promoting immunogenic cell death via TNF-induced necrosis to trigger antitumour immunity.

Enhancing Checkpoint Inhibitor Therapy with Ultrasound Stimulated Microbubbles

Checkpoint inhibitor (CI) immunotherapy is playing an increasingly prominent role in the treatment of cancer but is effective and durable in only a subset of patients. There are concerted efforts to improve CI therapy through the use of multiple CIs or use of CIs in combination with other anti-cancer agents. Here we investigate the use of "anti-vascular" ultrasound-stimulated microbubble (USMB) treatments in combination with anti-PD-1 CI therapy. The colorectal cancer cell line CT26 was used to conduct longitudinal growth studies along with acute experiments to assess ultrasound-induced anti-tumor immune responses using flow cytometry and enzyme-linked immunospot (ELISPOT) analysis. Longitudinal experiments indicated that USMB + anti-PD-1 treatments significantly enhanced tumor growth inhibition and animal survival relative to monotherapies. Flow cytometry and ELISPOT data did not clearly support a T cell-dependent mechanism for the enhancement. Therefore, the results indicate the ability of anti-vascular USMBs to increase the anti-tumor effects of CI therapy; the specific mechanisms of enhancement remain to be established.

A Light-Triggered Mesenchymal Stem Cell Delivery System for Photoacoustic Imaging and Chemo-Photothermal Therapy of Triple Negative Breast Cancer

Targeted therapy is highly challenging and urgently needed for patients diagnosed with triple negative breast cancer (TNBC). Here, a synergistic treatment platform with plasmonic-magnetic hybrid nanoparticle (lipids, doxorubicin (DOX), gold nanorods, iron oxide nanocluster (LDGI))-loaded mesenchymal stem cells (MSCs) for photoacoustic imaging, targeted photothermal therapy, and chemotherapy for TNBC is developed. LDGI can be efficiently taken up into the stem cells with good biocompatibility to maintain the cellular functions. In addition, CXCR4 on the MSCs is upregulated by iron oxide nanoparticles in the LDGI. Importantly, the drug release and photothermal therapy can be simultaneously achieved upon light irradiation. The released drug can enter the cell nucleus and promote cell apoptosis. Interestingly, light irradiation can control the secretion of cellular microvehicles carrying LDGI for targeted treatment. A remarkable in vitro anticancer effect is observed in MDA-MB-231 with near-infrared laser irradiation. In vivo studies show that the MSCs-LDGI has the enhanced migration and penetration abilities in the tumor area via both intratumoral and intravenous injection approaches compared with LDGI. Subsequently, MSCs-LDGI shows the best antitumor efficacy via chemo-photothermal therapy compared to other treatment groups in the TNBC model of nude mice. Thus, MSCs-LDGI multifunctional system represents greatly synergistic potential for cancer treatment.

Focused ultrasound for immuno-adjuvant treatment of pancreatic cancer: An emerging clinical paradigm in the era of personalized oncotherapy

Current clinical treatment regimens, including many emergent immune strategies (e.g., checkpoint inhibitors) have done little to affect the devastating course of pancreatic ductal adenocarcinoma (PDA). Clinical trials for PDA often employ multi-modal treatment, and have started to incorporate stromal-targeted therapies, which have shown promising results in early reports. Focused ultrasound (FUS) is one such therapy that is uniquely equipped to address local and systemic limitations of conventional cancer therapies as well as emergent immune therapies for PDA. FUS methods can non-invasively generate mechanical and/or thermal effects that capitalize on the unique oncogenomic/proteomic signature of a tumor. Potential benefits of FUS therapy for PDA include: (1) emulsification of targeted tumor into undenatured antigens in situ, increasing dendritic cell maturation, and increasing intra-tumoral CD8+/ T regulatory cell ratio and CD8+ T cell activity; (2) reduction in intra-tumoral hypoxic stress; (3) modulation of tumor cell membrane protein localization to enhance immunogenicity; (4) modulation of the local cytokine milieu toward a Th1-type inflammatory profile; (5) up-regulation of local chemoattractants; (6) remodeling the tumor stroma; (7) localized delivery of exogenously packaged immune-stimulating antigens, genes and therapeutic drugs. While not all of these results have been studied in experimental PDA models to date, the principles garnered from other solid tumor and disease models have direct relevance to the design of optimal FUS protocols for PDA. In this review, we address the pertinent limitations in current and emergent immune therapies that can be improved with FUS therapy for PDA.

Stably engineered nanobubbles and ultrasound - An effective platform for enhanced macromolecular delivery to representative cells of the retina

Herein we showcase the potential of ultrasound-responsive nanobubbles in enhancing macromolecular permeation through layers of the retina, ultimately leading to significant and direct intracellular delivery; this being effectively demonstrated across three relevant and distinct retinal cell lines. Stably engineered nanobubbles of a highly homogenous and echogenic nature were fully characterised using dynamic light scattering, B-scan ultrasound and transmission electron microscopy (TEM). The nanobubbles appeared as spherical liposome-like structures under TEM, accompanied by an opaque luminal core and darkened corona around their periphery, with both features indicative of efficient gas entrapment and adsorption, respectively. A nanobubble +/- ultrasound sweeping study was conducted next, which determined the maximum tolerated dose for each cell line. Detection of underlying cellular stress was verified using the biomarker heat shock protein 70, measured before and after treatment with optimised ultrasound. Next, with safety to nanobubbles and optimised ultrasound demonstrated, each human or mouse-derived cell population was incubated with biotinylated rabbit-IgG in the presence and absence of ultrasound +/- nanobubbles. Intracellular delivery of antibody in each cell type was then quantified using Cy3-streptavidin. Nanobubbles and optimised ultrasound were found to be negligibly toxic across all cell lines tested. Macromolecular internalisation was achieved to significant, yet varying degrees in all three cell lines. The results of this study pave the way towards better understanding mechanisms underlying cellular responsiveness to ultrasound-triggered drug delivery in future ex vivo and in vivo models of the posterior eye.

High-Intensity Focused Ultrasound- and Radiation Therapy-Induced Immuno-Modulation: Comparison and Potential Opportunities

In recent years, high-intensity focused ultrasound (HIFU) has emerged as a new and promising non-invasive and non-ionizing ablative technique for the treatment of localized solid tumors. Extensive pre-clinical and clinical studies have evidenced that, in addition to direct destruction of the primary tumor, HIFU-thermoablation may elicit long-term systemic host anti-tumor immunity. In particular, an important consequence of HIFU treatment includes the release of tumor-associated antigens (TAAs), the secretion of immuno-suppressing factors by cancer cells and the induction of cytotoxic T lymphocyte (CTL) activity. Radiation therapy (RT) is the main treatment modality used for many types of tumors and about 50% of all cancer patients receive RT, often used in combination with surgery and chemotherapy. It is well known that RT can modulate anti-tumor immune responses, modifying micro-environment and stimulating inflammatory factors that can greatly affect cell invasion, bystander effects, radiation tissue complications (such as fibrosis), genomic instability and thus, intrinsic cellular radio-sensitivity. To date, various combined therapeutic strategies (such as immuno-therapy) have been performed in order to enhance RT success in treating locally advanced and recurrent tumors. Recent works suggested the combined use of HIFU and RT treatments to increase the tumor cell radio-sensitivity, in order to synergize the effects reaching the maximum results with minimal doses of ionizing radiation (IR). Here, we highlight the opposite immuno-modulation roles of RT and HIFU, providing scientific reasons to test, by experimental approaches, the use of HIFU immune-stimulatory capacity to improve tumor radio-sensitivity, to reduce the RT induced inflammatory response and to decrease the dose-correlated side effects in normal tissues.

Thermal and mechanical high-intensity focused ultrasound: perspectives on tumor ablation, immune effects and combination strategies

Tumor ablation technologies, such as radiofrequency-, cryo- or high-intensity focused ultrasound (HIFU) ablation will destroy tumor tissue in a minimally invasive manner. Ablation generates large volumes of tumor debris in situ, releasing multiple bio-molecules like tumor antigens and damage-associated molecular patterns. To initiate an adaptive antitumor immune response, antigen-presenting cells need to take up tumor antigens and, following activation, present them to immune effector cells. The impact of the type of tumor ablation on the precise nature, availability and suitability of the tumor debris for immune response induction, however, is poorly understood. In this review, we focus on immune effects after HIFU-mediated ablation and compare these to findings using other ablation technologies. HIFU can be used both for thermal and mechanical destruction of tissue, inducing coagulative necrosis or subcellular fragmentation, respectively. Preclinical and clinical results of HIFU tumor ablation show increased infiltration and activation of CD4⁺ and CD8⁺ T cells. As previously observed for other types of tumor ablation technologies, however, this ablation-induced enhanced infiltration alone appears insufficient to generate consistent protective antitumor immunity. Therapies combining ablation with immune stimulation are therefore expected to be key to boost HIFU-induced immune effects and to achieve systemic, long-lasting, antitumor immunity.

Focused ultrasound-aided immunomodulation in glioblastoma multiforme: a therapeutic concept

Patients with glioblastoma multiforme (GBM) exhibit a deficient anti-tumor immune response. Both arms of the immune system were shown to be hampered in GBM, namely the local cellular immunity mediated by the Th₁ subset of helper T cells and the systemic humoral immunity mediated by the Th₂ subset of helper T cells. Immunotherapy is rapidly becoming one of the pillars of anti-cancer therapy. GBM has not received similar clinical successes as of yet, which may be attributed to its relative inaccessibility (the blood-brain barrier (BBB)), its poor immunogenicity, few characterized cancer antigens, or any of the many other immune mechanisms known to be hampered. Focused ultrasound (FUS) is emerging as a promising treatment approach. The effects of FUS on the tissue are not merely thermal. Mounting evidence suggests that in addition to thermal ablation, FUS induces mechanical acoustic cavitation and immunomodulation plays a key role in boosting the host anti-tumor immune responses. We separately discuss the different pertinent immunosuppressive mechanisms harnessed by GBM and the immunomodulatory effects of FUS. The effect of FUS and microbubbles in disrupting the BBB and introducing antigens and drugs to the tumor milieu is discussed. The FUS-induced pro-inflammatory cytokines secretion and stress response, the FUS-induced change in the intra-tumoral immune-cells populations, the FUS-induced augmentation of dendritic cells activity, and the FUS-induced increased cytotoxic cells potency are all discussed. We next attempt at offering a conceptual synopsis of the synergistic treatment of GBM utilizing FUS and immunotherapy. In conclusion, it is increasingly apparent that no single treatment modality will triumph on GBM. The reviewed FUS-induced immunomodulation effects can be harnessed to current and developing immunotherapy approaches. Together, these may overcome GBM-induced immune-evasion and generate a clinically relevant anti-tumor immune response.

Low-Energy Ultrasound Treatment Improves Regional Tumor Vessel Infarction by Retargeted Tissue Factor

OBJECTIVES

To enhance the regional antitumor activity of the vascular-targeting agent truncated tissue factor (tTF)-NGR by combining the therapy with low-energy ultrasound (US) treatment.

METHODS

For the in vitro US exposure of human umbilical vein endothelial cells (HUVECs), cells were put in the focus of a US transducer. For analysis of the US-induced phosphatidylserine (PS) surface concentration on HUVECs, flow cytometry was used. To demonstrate the differences in the procoagulatory efficacy of TF-derivative tTF-NGR on binding to HUVECs with a low versus high surface concentration of PS, we performed factor X activation assays. For low-energy US pretreatment, HT1080 fibrosarcoma xenotransplant-bearing nude mice were treated by tumor-regional US-mediated stimulation (ie, destruction) of microbubbles. The therapy cohorts received the tumor vessel-infarcting tTF-NGR protein with or without US pretreatment (5 minutes after US stimulation via intraperitoneal injection on 3 consecutive days).

RESULTS

Combination therapy experiments with xenotransplant-bearing nude mice significantly increased the antitumor activity of tTF-NGR by regional low-energy US destruction of vascular microbubbles in tumor vessels shortly before application of tTF-NGR (P < .05). Mechanistic studies proved the upregulation of anionic PS on the outer leaflet of the lipid bilayer of endothelial cell membranes by low-energy US and a consecutive higher potential of these preapoptotic endothelial cells to activate coagulation via tTF-NGR and coagulation factor X as being a basis for this synergistic activity.

CONCLUSIONS

Combining retargeted tTF to tumor vessels with proapoptotic stimuli for the tumor vascular endothelium increases the antitumor effects of tumor vascular infarction. Ultrasound treatment may thus be useful in this respect for regional tumor therapy.

Contrast Ultrasound Imaging Does Not Affect Heat Shock Protein 70 Expression in Cholesterol-Fed Rabbit Aorta

OBJECTIVES

Diagnostic ultrasound imaging is enhanced by the use of circulating microbubble contrast agents (UCAs), but the interactions between ultrasound, UCAs, and vascular tissue are not fully understood. We hypothesized that ultrasound with a UCA would stress the vascular tissue and increase levels of heat shock protein 70 (Hsp70), a cellular stress protein.

METHODS

Male New Zealand White rabbits (n = 32) were fed a standard chow diet (n = 4) or a 1% cholesterol, 10% fat, and 0.11% magnesium diet (n = 28). At 21 days, 24 rabbits on the cholesterol diet were either exposed to ultrasound (3.2-MHz f/3 transducer; 2.1 MPa; mechanical index, 1.17; 10 Hz pulse repetition frequency; 1.6 microseconds pulse duration; 2 minutes exposure duration at 4 sites along the aorta) with the UCA Definity (1× concentration, 1 mL/min; Lantheus Medical Imaging, North Billerica, MA) or sham exposed with a saline vehicle injection (n = 12 per group). Four rabbits on the cholesterol diet and 4 on the chow diet served as cage controls and were not exposed to ultrasound or restrained for blood sample collection. Animals were euthanized 24 hours after exposure, and aortas were quickly isolated and frozen in liquid nitrogen. Aorta lysates from the area of ultrasound exposure were analyzed for Hsp70 level by Western blot. Blood plasma was analyzed for cholesterol, Hsp70, and von Willebrand factor, a marker of endothelial function.

RESULTS

Plasma total cholesterol levels increased to an average of 705 mg/dL. Ultrasound did not affect plasma von Willebrand factor, plasma Hsp70, or aorta Hsp70. Restraint increased Hsp70 (P < .001, analysis of variance).

CONCLUSIONS

Restraint, but not ultrasound with the UCA or cholesterol feeding, significantly increased Hsp70.

High intensity focused ultrasound ablation and antitumor immune response

The ideal cancer therapy not only induces the death of all localized tumor cells without damage to surrounding normal tissue, but also activates a systemic antitumor immunity. High intensity focused ultrasound (HIFU) has the potential to be such a treatment, as it can non-invasively ablate a targeted tumor below the skin surface, and may subsequently augment host antitumor immunity. This paper is to review increasing pre-clinical and clinical evidence linking antitumor immune response to HIFU ablation, and to discuss the potential mechanisms involved in HIFU-enhanced host antitumor immunity. The seminal studies performed so far indicate that although it is not possible to conclude definitively on the connection between HIFU treatment and antitumor immune response, it is nonetheless important to conduct extensive studies on the subject in order to elucidate the processes involved.

Combination therapy with local radiofrequency ablation and systemic vaccine enhances antitumor immunity and mediates local and distal tumor regression

Purpose

Radiofrequency ablation (RFA) is a minimally invasive energy delivery technique increasingly used for focal therapy to eradicate localized disease. RFA-induced tumor-cell necrosis generates an immunogenic source of tumor antigens known to induce antitumor immune responses. However, RFA-induced antitumor immunity is insufficient to control metastatic progression. We sought to characterize (a) the role of RFA dose on immunogenic modulation of tumor and generation of immune responses and (b) the potential synergy between vaccine immunotherapy and RFA aimed at local tumor control and decreased systemic progression.

Experimental Design

Murine colon carcinoma cells expressing the tumor-associated (TAA) carcinoembryonic antigen (CEA) (MC38-CEA⁺) were studied to examine the effect of sublethal hyperthermia in vitro on the cells’ phenotype and sensitivity to CTL-mediated killing. The effect of RFA dose was investigated in vivo impacting (a) the phenotype and growth of MC38-CEA⁺ tumors and (b) the induction of tumor-specific immune responses. Finally, the molecular signature was evaluated as well as the potential synergy between RFA and poxviral vaccines expressing CEA and a TRIad of COstimulatory Molecules (CEA/TRICOM).

Results

In vitro, sublethal hyperthermia of MC38-CEA⁺ cells (a) increased cell-surface expression of CEA, Fas, and MHC class I molecules and (b) rendered tumor cells more susceptible to CTL-mediated lysis. In vivo, RFA induced (a) immunogenic modulation on the surface of tumor cells and (b) increased T-cell responses to CEA and additional TAAs. Combination therapy with RFA and vaccine in CEA-transgenic mice induced a synergistic increase in CD4⁺ T-cell immune responses to CEA and eradicated both primary CEA⁺ and distal CEA^– s.c. tumors. Sequential administration of low-dose and high-dose RFA with vaccine decreased tumor recurrence compared to RFA alone. These studies suggest a potential clinical benefit in combining RFA with vaccine in cancer patients, and augment support for this novel translational paradigm.

Use of in vivo bioluminescence and MRI to determine hyperthermia-induced changes in luciferase activity under the control of an hsp70 promoter

We investigated the in vivo effect of hyperthermia on the expression of heat shock proteins and MRI changes in three tumor cell lines. Three tumor cell lines (SCCVII, NIH3T3, M21) were transfected with a plasmid containing the heat shock protein 70 gene (hsp70) promoter fragment and the luciferase reporter gene, and injected into mice. Tumors of 1100 mm³ in size were exposed to five different temperatures (38, 40, 42, 44 and 46 °C) in a water bath. Bioluminescence and MRI were performed at set time intervals. The MRI scan protocol was as follows: T₁-weighted spin echo ± contrast medium, T₂-weighted fast spin echo, dynamic contrast-enhanced MRI, diffusion-weighted stimulated echo acquisition mode sequence, T₂ time obtained on a 1.5T General Electric MRI scanner. Immunoblotting was also performed. hsp70 transcription was strongly induced at 42 and 44 °C, reaching values as high as 8531.5 ± 432.1-fold above baseline in NIH3T3 tumors. At these temperatures, significant increases in the uptake of contrast medium, slope of initial enhancement, Ak(ep) values and apparent diffusion coefficient (ADC) were observed in the 8-h scan of the NIH3T3 cell line. In SCCVII tumors, ADC increased by about 23% (p = 0.010) in the scans performed at 8, 24, 48 and 96 h. At 46 °C, luciferase activity was reduced significantly in the three cell lines. In all tumor types, a significant increase in ADC was observed, which was highest in SCCVII tumors (33.8%; p < 0.01). In accordance with the bioluminescence results, significant Hsp70 protein production was shown by immunoblot analysis. The best correlation coefficient between luciferase activity and immunoblotting results was found for M21 tumors (r = 0.93, p < 0.0001). Different tissue types display distinct patterns of hsp70 transcription. MRI can be used, in combination with optical imaging, to provide information on hsp70 transcription and protein production. The major finding of the present study was that heat-related biochemical changes in tumor tissue can be determined by MRI.

High-intensity focused ultrasound tumor ablation activates autologous tumor-specific cytotoxic T lymphocytes

Previous studies have shown that high-intensity focused ultrasound (HIFU) ablation can enhance host antitumor immune response, though the mechanism is still unknown. In the present study, we investigated whether HIFU ablation could activate tumor-specific T lymphocytes and then induce antitumor cellular immunity. We studied 70 C57BL/6J mice bearing the H(22) tumor; they were randomly divided into a HIFU group and a sham-HIFU group. Of the mice, 35 in the HIFU group underwent HIFU ablation of the H(22) hepatic tumor, and the remaining 35 received a sham-HIFU procedure. In addition, 35 female, naïve syngeneic C57BL/6J mice were used as controls. All mice were sacrificed 14 days after HIFU, and the spleens were harvested. The function of T lymphocytes was determined. As a valuable tool for detecting and characterizing peptide-specific cells, the frequency of MHC class I tetramer/CD8-positive cells was quantified, which could help to determine the response and number of T lymphocytes. The therapeutic effect of the HIFU-activated lymphocytes on tumor-bearing mice was investigated after adoptive transfer of the lymphocytes. The results showed that compared to sham-HIFU and control groups, HIFU ablation significantly increased the cytotoxicity of cytotoxic T lymphocytes (p < 0.05), with a significant increase of IFN-γ and TNF-α secretion (p < 0.001). The frequency of the MHC class I tetramer/CD8-positive cells was significantly higher in the HIFU group (p < 0.05). A stronger inhibition of tumor progression and higher survival rates were observed to be significant after adoptive immunotherapy in the HIFU group as compared to the sham-HIFU and control groups (p < 0.01). It is concluded that HIFU ablation could activate tumor-specific T lymphocytes, thus inducing antitumor cellular immune responses in tumor-bearing mice.

Induction of luciferase activity under the control of an hsp70 promoter using high-intensity focused ultrasound: combination of bioluminescence and MRI imaging in three different tumour models

The in vivo temporal changes of luciferase activity were investigated under the control of an hsp70 promoter in three tumour models after the application of different intensities of high-intensity focused ultrasound (HIFU). Three cell lines, SCCVII, NIH3T3 and M21 were stably transfected with a plasmid containing the hsp70 promoter and luciferase reporter gene, and tumours were subcutaneously initiated into mice. At a size of 1300 ± 234 mm(3), the tumours were exposed to five intensities of continuous HIFU (802-1401-2157-3067-4133 W/cm(2)) for 20 sec. Bioluminescence and MR imaging were performed to assess luciferase activity and signal intensity changes in the tissue. The MRI scan protocol was pre- and post-contrast T1-wt-SE, T2-wt-FSE, DCE-MRI, diffusion-wt STEAM sequence, T2 relaxation time determination obtained on a 1.5-T GE MRI scanner. The NIH3T3 tumours showed the highest luciferase activity of 328.1 ± 7.1 fold at 24 h at a HIFU intensity of 3067 W/cm(2), the M21 tumours of 3.2 ± 0.6 fold 8 hours and the SCCVII tumours 2.9 ± 0.9 fold 4 hours post-HIFU at 2157 W/cm(2). The greatest increase in T2 signal intensity and T2 relaxation time of 20.7 ± 3.4% was seen in the SCCVII tumours. The highest contrast medium uptake of 10.1 ± 1.1% was noted in the M21 tumours, and 14.8 ± 1.9% in the SCCVII tumours. In all tumours, a significant increase in the diffusion coefficient was seen with increased HIFU intensity, the highest of which was 40.3 ± 4.1% in the SCCVII tumours. The three tumour cell lines stably transfected with the hsp70/luciferase gene showed differential luciferase activity, which peaked at different times after the application of HIFU and was dependant on tumour type and HIFU energy deposition.

Combination of cell delivery and thermoinducible transcription for in vivo spatiotemporal control of gene expression: a feasibility study

PURPOSE

To demonstrate the feasibility of combining in situ delivery of genetically modified cells into the rat kidney, to induce expression of a reporter gene under transcriptional control of a heat-inducible promoter activated with magnetic resonance (MR)-guided focused ultrasonography (US), and to demonstrate in vivo the local expression of the synthesized protein.

MATERIALS AND METHODS

Experiments were conducted in agreement with the European Commission guidelines and directives of the French Research Ministry. C6 cells were genetically modified by incorporating the firefly luciferase (LucF) gene under transcriptional control of a heat-sensitive promoter (human heat shock protein 70B). Engineered cells were injected in the renal artery of a superficialized left kidney (15 rats). Two days later, intrarenal LucF expression was induced noninvasively by local hyperthermia in 15 renal locations in nine rats with focused US and was controlled with MR temperature imaging. Six hours after heating, LucF activity was detected in vivo with bioluminescence imaging.

RESULTS

The genetically engineered C6 cell line was characterized in vitro for LucF expression related to the heating parameters. Changes in renal morphology and hemodynamic parameters as a result of rat kidney superficialization were not significant. Intrarenal temperature measurement at the focal point followed the scheduled temperature in 13 of 15 cases. On bioluminescence images, LucF activity was present only in heated regions. The level of LucF expression was also dependent on heating parameters. Substantial tissue damage was noted at histologic analysis in only the two cases in which temperature control was inadequate.

CONCLUSION

A strategy combining cell delivery of a transgene and a thermosensitive promoter that can be locally activated with MR-guided focused US is able to induce in vivo gene expression controlled in space and time.

SUPPLEMENTAL MATERIAL

http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.10100767/-/DC1.

Enhancement of antitumor vaccine in ablated hepatocellular carcinoma by high-intensity focused ultrasound

AIM: To investigate whether tumor debris created by high-intensity focused ultrasound (HIFU) could trigger antitumor immunity in a mouse hepatocellular carcinoma model.

METHODS: Twenty C57BL/6J mice bearing H22 hepatocellular carcinoma were used to generate antitumor vaccines. Ten mice underwent HIFU ablation, and the remaining 10 mice received a sham-HIFU procedure with no ultrasound irradiation. Sixty normal mice were randomly divided into HIFU vaccine, tumor vaccine and control groups. These mice were immunized with HIFU-generated vaccine, tumor-generated vaccine, and saline, respectively. In addition, 20 mice bearing H22 tumors were successfully treated with HIFU ablation. The protective immunity of the vaccinated mice was investigated before and after a subsequent H22 tumor challenge. Using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, the cytotoxicity of splenic lymphocytes co-cultured with H22 cells was determined in vitro before the tumor challenge, and tumor volume and survival were measured in vivo after the challenge in each group. The mechanism was also explored by loading the vaccines with bone marrow-derived dendritic cells (DCs).

RESULTS: Compared to the control, HIFU therapy, tumor-generated and HIFU-generated vaccines significantly increased cytolytic activity against H22 cells in the splenocytes of the vaccinated mice (P < 0.001). The tumor volume was significantly smaller in the HIFU vaccine group than in the tumor vaccine group (P < 0.05) and control group (P < 0.01). However, there was no tumor growth after H22 rechallenge in the HIFU therapy group. Forty-eight-day survival rate was 100% in mice in the HIFU therapy group, 30% in both the HIFU vaccine and tumor vaccine groups, and 20% in the control group, indicating that the HIFU-treated mice displayed significantly longer survival than the vaccinated mice in the remaining three groups (P < 0.001). After bone marrow-derived DCs were incubated with HIFU-generated and tumor-generated vaccines, the number of mature DCs expressing MHC-II⁺, CD80⁺ and CD86⁺ molecules was significantly increased, and interleukin-12 and interferon-γ levels were significantly higher in the supernatants when compared with immature DCs incubated with mouse serum (P < 0.001). However, no differences of the number of mature DCs and cytokine levels were observed between the HIFU-generated and tumor-generated vaccines (P > 0.05).

CONCLUSION: Tumor debris remaining after HIFU can improve tumor immunogenicity. This debris releases tumor antigens as an effective vaccine to develop host antitumor immune response after HIFU ablation.

Sonoporation, drug delivery, and gene therapy

Ultrasound is a very effective modality for drug delivery and gene therapy because energy that is non-invasively transmitted through the skin can be focused deeply into the human body in a specific location and employed to release drugs at that site. Ultrasound cavitation, enhanced by injected microbubbles, perturbs cell membrane structures to cause sonoporation and increases the permeability to bioactive materials. Cavitation events also increase the rate of drug transport in general by augmenting the slow diffusion process with convective transport processes. Drugs and genes can be incorporated into microbubbles, which in turn can target a specific disease site using ligands such as the antibody. Drugs can be released ultrasonically from microbubbles that are sufficiently robust to circulate in the blood and retain their cargo of drugs until they enter an insonated volume of tissue. Local drug delivery ensures sufficient drug concentration at the diseased region while limiting toxicity for healthy tissues. Ultrasound-mediated gene delivery has been applied to heart, blood vessel, lung, kidney, muscle, brain, and tumour with enhanced gene transfection efficiency, which depends on the ultrasonic parameters such as acoustic pressure, pulse length, duty cycle, repetition rate, and exposure duration, as well as microbubble properties such as size, gas species, shell material, interfacial tension, and surface rigidity. Microbubble-augmented sonothrombolysis can be enhanced further by using targeting microbubbles.

Dendritic cells loaded with ultrasound-ablated tumour induce in vivo specific antitumour immune responses

Previous studies have shown that high-intensity focused ultrasound (HIFU) ablation can induce a local inflammation with marked infiltration of dendritic cells (DCs). The purpose of this study was to investigate whether DCs could capture and present activating signals delivered by necrotic tumour cells that remain in situ after HIFU, thus initiating specific antitumour immunity. Tumour debris was derived from a mouse H22 tumour model after HIFU ablation. Bone marrow-derived DCs were loaded with HIFU-treated tumour, tumour lysate and mouse serum. Syngeneic naïve C57BL/6J mice were immunised with three loaded DCs followed by a subsequent H22 tumour challenge. Tumour size and survival were then recorded in each vaccinated mouse. The results showed that both HIFU-ablated tumour and tumour lysate could significantly increase the number of mature DCs and the secretion of IL-12 and IFN-gamma (p<0.001). The proliferation of splenic lymphocytes co-incubated with the loaded-DCs was significantly higher in both HIFU-ablated tumour and tumour lysate groups (p<0.01). Cytotoxocity and TNF-alpha and IFN-gamma secretion of cytotoxic T lymphocytes against H22 cells were significantly higher in HIFU-ablated tumour group than that in tumour lysate group (p<0.01). After the H22 tumour challenge, a significant decrease of tumour volume was observed in HIFU-ablated tumour group (p<0.01). However, there was no statistical difference of long-term survival rates among three groups (p>0.05). It is concluded that DCs can be activated by HIFU-ablated tumour debris and, thus, initiate host specific antitumour immune response after HIFU therapy.

The effect of high intensity focused ultrasound on luciferase activity on two tumor cell lines in vitro, under the control of a CMV promoter

In this study, we compared the effect of high intensity focused ultrasound (HIFU) and thermal stress on the luciferase activity, controlled by a cytomegaly virus (CMV) promoter in an in vitro model using two tumor cell lines (M21, SCCVII). HIFU was applied in a pulsed-wave mode with increasing voltage at constant pulse duration, or thermal stress was delivered over a range of temperatures (36-52 degrees C) for 5 min. The resulting luciferase activity was measured in live cells using a cooled CCD camera. Luciferase activity was measured at set time intervals over a total of 48 h post-stress. Compared to baseline, the luciferase activity of the M21 tumor cell line when exposed to HIFU was approximately 54.2+/-67.5% (p<0.01) higher at a temperature of 42 degrees C, and approximately 52.9+/-128.5% (p<0.01) higher at 44 degrees C. In the SCCVII tumor cell line, the luciferase activity after HIFU application was 55.4+/-66.6% (p<0.01) higher compared to baseline at a temperature of 42 degrees C. The M21 and SCCVII tumor cell line when exposed to thermal stress alone did not increase the luciferase activity. M21 and SCCVII tumor cells exposed to HIFU showed a maximum decrease in cell viability to 45.3+/-7.5% and 10.3+/-7.5%, respectively, and when exposed to thermal stress to 85.3+/-3.5% and 20.4+/-6.5%, respectively, compared to the untreated control. In M21 and SCCVII cells exposed to HIFU, free radicals could be detected using the dichlorofluorescein dye. Our findings demonstrate that HIFU can enhance the luciferase activity controlled by a CMV promoter. However it also has a higher damaging effect on the cells.

Increased infiltration of activated tumor-infiltrating lymphocytes after high intensity focused ultrasound ablation of human breast cancer

BACKGROUND

Previous studies have shown that high intensity focused ultrasound (HIFU) ablation can induce a distinct inflammatory reaction with marked infiltration of lymphocytes after direct tumor destruction. In this study, we investigated the status of tumor-infiltrating lymphocytes (TILs) after HIFU ablation of human breast cancer and explored mechanisms that may be involved in HIFU-triggered, antitumor immune response.

METHODS

A total of 48 female patients with biopsy-proven breast cancer were divided randomly into 1 of 2 groups: control group (n = 25), in which only modified radical mastectomy was performed, or HIFU group (n = 23), in which HIFU ablation of the primary breast cancer was performed prior to modified radical mastectomy. Using semiquantitative immunohistochemical analysis, tumor-infiltrating T lymphocytes and subsets, B lymphocytes, and natural killer (NK) cells were assessed in all patients. Expression of Fas ligand (FasL), granzyme, and perforin on TILs was also studied in both groups.

RESULTS

TILs infiltrated along the margins of the ablated region in all HIFU-treated neoplasms, and the numbers of tumor-infiltrating CD3, CD4, CD8, CD4/CD8, B lymphocytes, and NK cells was increased significantly in the HIFU group. The number of FasL(+), granzyme(+), and perforin(+) TILs was significantly greater in the HIFU group than in the control group.

CONCLUSION

HIFU ablation induced marked infiltration of CD3, CD4, CD8, B lymphocytes, and NK cells in the treated breast lesions. The number of FasL(+), granzyme(+), and perforin(+) TILs was significantly increased after HIFU treatment.

Expression of heat shock protein 60 in the tissues of transported piglets

In this study, we sought to determine the distribution and expression of heat shock protein 60 (Hsp60) in the tissues of transported piglets. A total of 24 Chinese Erhualian piglets with an average body weight of 20 +/- 1 kg were assessed under both 2-h transported and normal housing conditions. Results of enzymatic analysis showed that the serum creatine kinase and aspartate aminotransferase concentrations were significantly increased in the 2-h transported piglets. Acute cellular lesions characterized by granular and vacuolar degeneration of the parenchyma cells in the tested heart, liver, and kidney were also confirmed by histopathological test after 2 h transportation. These results indicate that transport stress induces tissue damage to heart, liver, and kidney. Hsp60-positive immunostaining was consistently detected in the cytoplasm of myocardial cells, hepatocytes, renal tubular epithelial cells, and epithelial cells of fundic gland. However, results of enzyme-linked immunosorbent assay indicated that Hsp60 expression was only significantly elevated in the stomach, with lower expression in the heart and a non-significant trend of increased liver and kidney expression of Hsp60. These results indicate that different tissues had different sensitivities to transport stress, possibly resulting in varying levels of cytoprotection by Hsp60 in the different tissues. The expression of Hsp60 following 2 h transportation coincided with deterioration of cardiac cytoprotection in the heart and protection in the stomach. However, the direct role of Hsp60 in cytoprotection of heart and stomach tissues needs further investigation.