High energy underwater shock wave treatment on implanted urinary bladder cancer in rabbits

Shock wave-induced permeabilization of mammalian cells

Controlled permeabilization of mammalian cell membranes is fundamental to develop gene and cell therapies based on macromolecular cargo delivery, a process that emerged against an increasing number of health afflictions, including genetic disorders, cancer and infections. Viral vectors have been successfully used for macromolecular delivery; however, they may have unpredictable side effects and have been limited to life-threatening cases. Thus, several chemical and physical methods have been explored to introduce drugs, vaccines, and nucleic acids into cells. One of the most appealing physical methods to deliver genes into cells is shock wave-induced poration. High-speed microjets of fluid, emitted due to the collapse of microbubbles after shock wave passage, represent the most significant mechanism that contributes to cell membrane poration by this technique. Herein, progress in shock wave-induced permeabilization of mammalian cells is presented. After covering the main concepts related to molecular strategies whose applications depend on safer drug delivery methods, the physics behind shock wave phenomena is described. Insights into the use of shock waves for cell membrane permeation are discussed, along with an overview of the two major biomedical applications thereof-i.e., genetic modification and anti-cancer shock wave-assisted chemotherapy. The aim of this review is to summarize 30 years of data showing underwater shock waves as a safe, noninvasive method for macromolecular delivery into mammalian cells, encouraging the development of further research, which is still required before the introduction of this promising tool into clinical practice.

Transurethral bladder cryoablation in the porcine model

OBJECTIVES

To examine the feasibility of transurethral, focal, full-thickness bladder wall cryoablation in the porcine model using a novel 38-cm cryoablation probe.

METHODS

A total of 18 pigs were divided into three groups. Groups 1 (n = 6) and 2 (n = 6) underwent transurethral bladder wall cryoablation in a saline environment with two freeze-thaw cycles. The pigs in groups 1 and 2 were killed after 1 and 3 weeks, respectively. The pigs in group 3 (n = 6) underwent transurethral cryoablation after the bladder had been insufflated with carbon dioxide gas. The pigs in group 3 were killed after 1 week. In all groups, laparoscopic access was obtained to protect the abdominal contents from the transmural cryoablation process. Bladder integrity was evaluated with cystography and laparoscopic visualization, and each cryolesion was excised en bloc for extensive histopathologic evaluation.

RESULTS

All 18 pigs successfully underwent bladder wall cryoablation. For all groups, the preoperative, postoperative, and sacrifice cystograms were without evidence of extravasation. No urinomas, hematomas, or adhesions were present in groups 1 and 2. Minimal adhesions were identified in 3 (50%) of 6 pigs in group 3. For groups 1, and 2, the mean length and width of the area of complete necrosis on histopathologic evaluation was 6.5 and 3.0 mm and 2.3 and 1.3 mm, respectively. For group 3, the mean diameter of the cryolesion was 8.2 mm. Full-thickness necrosis was confirmed in all groups.

CONCLUSIONS

The results of our study have shown that, in this model, complete full-thickness transurethral bladder wall cryoablation, with maintenance of bladder wall integrity, is feasible.

High-energy shockwaves and extracorporeal high-intensity focused ultrasound

We review the physical interactions of focused ultrasound with tissue, describe technical features of current high-energy shockwave (HESW) and extracorporeal high-intensity focused ultrasound (HIFU) devices, and summarize the experimental and human data available to date. Tissue destruction by extracorporeal HIFU is not new: the first clinical attempts were made almost half a century ago for ablating brain tissue. Despite recent progress in the knowledge of the interactions between HIFU and tissue and significant device modifications, this technique is still in its infancy. The most promising targets for this kind of therapy in the field of urology are the kidney, bladder, and testis. The largest clinical experience with HIFU therapy currently available is for benign prostatic enlargement and prostate cancer using transrectal HIFU devices, which are not the topic of this summary. In parallel with HIFU, HESW therapy has been tested in numerous experimental and preclinical settings. This technique is currently not in routine clinical use. Theoretically, in parallel with HIFU, any organ accessible to conventional diagnostic ultrasound examination is a potential target for this kind of therapy.

Mechanism of anti-tumor effect of combination of bleomycin and shock waves

We have previously reported marked enhancement of the cytocidal effect of bleomycin (BLM) on cancer cell suspensions in vitro by the combination with shock waves. In this study, we evaluated the synergistic effects on cancer cell proliferation and apoptosis in solid tumors. A spherical piezo-ceramic element was used as the shock wave source, with a pressure peak of 40 MPa. A human colon cancer cell line, SW480 was implanted onto the back of nude mice. Two thousand shock waves were administered to the tumor immediately following an intravenous injection of BLM at a dose of one-tenth of the LD(50). The tumor was extirpated at 3, 6, 12, 24, 72 h and 1 week following shock exposure. Cell proliferation and apoptosis were detected by Ki-67 using antibody MIB-1 and by the terminal deoxynucleotidyl transferase (TdT)-mediated dUTP-biotin nick-end labeling (TUNEL) method. The lowest percentage (35.7%) of Ki-67-positive cells appeared 24 h following the treatment. The maximum apoptotic index was detected within 6 h following the treatment. Moreover, numerous large cells with enlarged nuclei were detected histologically. These results suggest that shock waves may enhance chemotherapeutic effects by increasing apoptosis and decreasing cell proliferation in the tumor tissue.

Erosion of artificial endothelia in vitro by pulsed ultrasound: acoustic pressure, frequency, membrane orientation and microbubble contrast agent dependence

The erosion of cells from fibroblast monolayers simulating the vascular endothelium by 20 micros pulses of ultrasound at 500 Hz PRF was studied in relation to the peak negative acoustic pressure (P-; 0.0-2.5 MPa), ultrasound (US) frequency (1.0, 2.1 or 3.5 MHz), orientation of the monolayer (i.e., simulating the sites of ultrasound entry/exit from a blood vessel) and the presence or absence of a microbubble contrast agent (3 Vol% Albunex). The a priori hypotheses were that erosion of the monolayers would: 1. arise due to insonation treatment, 2. arise as a consequence of cavitation activity and, thus, increase with increasing P- at constant frequency, and decrease with increasing frequency at constant P-, 3. be significantly increased by the presence of a microbubble contrast agent, and 4. have a weak dependence on monolayer orientation. The data support these hypotheses. Under the most severe exposure conditions used, most of the affected cells appeared to have been lysed; however, a substantial number of viable cells were dislodged from the monolayer surface.

Synergistic interaction of ultrasonic shock waves and hyperthermia in the Dunning prostate tumor R3327-AT1

Pulsed high-energy ultrasound shock waves (PHEUS), similar to those used for clinical lithotripsy, can deposit energy deep in tissue and thereby destroy the microvasculature of solid tumors. We investigated the potential of PHEUS, generated by an electromagnetic shockwave source (19 kV capacitor voltage, 1 Hz pulse frequency), as a local cancer-therapy modality alone and in combination with local tumor hyperthermia (43.5 +/- 0.1 degrees C, 30 min). Copenhagen rats transplanted with the anaplastic Dunning-prostate-tumor sub-line R3327-AT1 received 1000 PHEUS pulses, which delayed tumor growth by one tumor-doubling time (5 days). Histopathology revealed hemorrhage, disruption of tumor vasculature, and necrosis in the focus of the sound field. Bromodeoxyuridine (BUdR) incorporation was significantly lower in PHEUS-treated tumors than in controls. Dynamic magnetic resonance imaging (MRI) studies using gadolinium-DTPA as contrast agent showed a strong reduction of tumor perfusion after PHEUS treatment, although this effect was partly reversible within 3 days after PHEUS. While hyperthermia alone produced no significant delay in tumor growth, the combination of PHEUS and hyperthermia produced tumor-growth delay by 2 tumor-volume-doubling times. The maximum growth delay was achieved when PHEUS and hyperthermia were separated by 24 hr at the time of maximum perfusion reduction indicated by MRI. Thus, the cytotoxic effect of PHEUS was enhanced by hyperthermia in the anaplastic prostate tumor R3327-AT1 grown on Copenhagen rats in a synergistic manner, due to blood-flow reduction. In conjunction with other agents, such as hyperthermia, PHEUS might become a local cancer-therapy modality in solid tumors accessible to ultrasound.

The influence of high-energy shock waves on the development of metastases

The hypothesis that exposure of a solid tumor to high-energy shock waves (HESW) could lead to an increase of metastases was investigated in an animal model. The highly metastatic AT-6 Dunning R3327 rat prostate cancer subline was implanted in the hind limb of a Fisher-Copenhagen rat and was exposed to 6000 shock waves delivered by an experimental lithotripter, or sham-treated, as soon as the tumor had reached a volume of 175-225 mm3. The tumor-bearing leg was amputated 24 h later and the number of metastases was examined 12 weeks thereafter at autopsy. Metastases were seen in 82% of the animals exposed to HESW and in 25% of the sham-treated animals. There was no significant difference in weight of the lungs that contained metastases, between sham and treated animals. These results were confirmed in a second experiment. We conclude that the metastatic spread of tumors with a high metastatic potential may be enhanced by shock-wave exposure.

Mechanisms of shockwave action in the human kidney

The effects on the human kidney parenchyma of high-energy shockwaves (HESW) with different energy densities were examined. Kidneys of patients treated by radical nephrectomy for renal cell carcinoma were perfused with cold HTK solution immediately after nephrectomy and kept in hypothermia (8 degrees C) for a maximum of 4 hours. The tumor-free parenchyma was treated with 2000 shocks at energy outputs of 15 kV (16 MPa, 0.15 mJ/mm2), 17 kV (32 MPa, 0.25 mJ/mm2), 19 kV (50 MPa, 0.4 mJ/mm2), and 21 kV (65 MPa, 0.6 mJ/mm2) in an experimental electromagnetic shockwave system (Siemens Co., Erlanger, Germany). Resulting tissue effects were analyzed by histologic and immunohistochemical examinations and confocal laser scanning microscopy. Different sensitivities of cell components, blood vessels, and tubules were found. Laser scanning microscopy revealed nuclear alterations in the vicinity of the focus up to a distance of approximately 10 mm. Severe histologic changes were found in a smaller zone, while immunohistochemistry studies revealed negative collagen IV staining in an area of approximately 4 x 4 mm (all distances measured within the plane perpendicular to the acoustic axis). From these results, it can be concluded that HESW directly damage the tubules and the vascular system, which might explain the clinical changes after extracorporeal shockwave lithotripsy in human patients. The extent of these effects seems to be dependent on the applied energy.

High-energy underwater shock wave treatment for internal iliac muscle metastasis of prostatic cancer: a first clinical trial

The first clinical trial of high-energy shock wave (SW) combined with chemotherapy to treat metastasis of prostate cancer in the internal iliac muscle was conducted. The patient, a 57-year-old man, diagnosed as having mucin-producing, poorly differentiated adenocarcinoma of the prostate invading the bladder wall, had been treated by total cystoprostatectomy. Five months later, metastatic tumors were found in the left axillar subcutaneous tissue and the right internal iliac muscles. For the axillar metastasis we performed radiation and left subclavicular arterial infusion of cisplatin 70 mg, THP-adriamycin (THP) 50 mg and methotrexate 50 mg. For the right internal muscular metastasis, 10,000 to 20,000 shots of SW and simultaneous intravenous injection of carboplatin 100 mg and THP 10 mg were carried out. Neither of the tumors decreased in size, but on magnetic resonance images, the SW-treated tumor exhibited a central low-intensity area. The SW-treated tumor was resected and central necrosis and a collection of mucin in the central area were observed. Hormone-resistant prostate cancer is well-known to be a multidrug-resistant tumor. It is noteworthy that SW and chemotherapy induced necrosis in such a refractory cancer without any significant side effects.

The effects of successive high-energy shock-wave tumor administration on tumor blood flow

The effects of repeated high-energy shock wave (HESW) tumor administration on tumor blood flow (TBF) were studied in NU-1 human kidney cancer xenografts. Deuteriated water was used as a magnetic resonance spectroscopic detectable tracer for measuring tumor blood flow. Tumors were exposed twice to 800 electromagnetically generated HESW, with a 24-h interval or sham exposed. No changes in TBF occurred after sham exposure to HESW. TBF levels 2 h after the first and second HESW application were, respectively, 46% and 37% lower than the mean preexposure TBF value and returned to normal levels within 16 h. There was statistically no difference found between the effects on tumor blood flow after the first and second HESW exposure. These observations are in agreement with earlier studies and provide a rationale to shorten the time interval between HESW monotreatments to 2 to 3 h.

High energy shock waves induced increase in the local concentration of systemically given TNF-alpha

The influence of high energy shock waves (HESW) on the local concentration of systemically given TNF-alpha was studied in a syngeneic rat bladder tumor model. 125I-TNF-alpha was injected intravenously and within 1 minute was followed by HESW tumor exposure. High energy shock waves were generated using an experimental shock wave emitter based on the Siemens Lithostar Plus. Administration of HESW to RBT323 tumors resulted in a 3-fold increase in uptake of 125I-TNF-alpha in the tumor compared with nontreated tumors, whereas the tissue distribution and pharmacokinetics of nontumor tissue were similar irrespective of HESW exposure. These results demonstrate that HESW administration leads to an increase in the local concentration of a systemically given drug. The capacity of HESW to increase local drug concentrations will be of importance in designing more effective combined treatment strategies.

Effects of high energy shock waves on tumor blood flow and metabolism: 31P/1H/2H nuclear magnetic resonance study

The effects of high energy shock waves (HESW) on tumor cell metabolism and tumor blood flow were studied in the NU-1 kidney cancer xenograft by multinuclear 1H/2H/31P magnetic resonance spectroscopy. Tumor xenografts were exposed to 800 HESW using an experimental electromagnetic shock wave emitter based on the Siemens Lithostar Plus, which is used for clinical lithotripsy. Exposure of tumors to 800 HESW resulted in a temporary decrease of tumor blood flow (TBF) determined by the 2H NMR monitoring of the 2HO1H wash-out after intratumoral injection. By concomitant recording of 31P and 1H NMR spectra, tumor pH, high-energy phosphates and lactate levels were followed. Tumor treatment with HESW transiently resulted in acidification, ATP decrease, P(i) increase and lactate increase. In contrast, HESW administration adjacent to the tumor did not significantly influence TBF, tumor pH, high-energy phosphates or lactate levels, showing that the observed alterations are caused by an interaction of HESW and tumor tissue. The most likely explanation for these observations is that HESW administration causes local vascular malfunctioning followed by a reduction in oxygen and nutrient supply to the tumor which leads to a decreased aerobic energy metabolism. The results of this study may be used to aid the design of HESW-based therapies.

Cytocidal effect of high energy shock wave on tumour cells enhanced with larger dose and multiple exposures

Cultured LLC-WRC256 (Walker rat carcinoma) cells were exposed to different doses of high energy shock waves (HESW). The immediate viabilities were 98% in the control cells, and 74%, 53% and 18% following 400, 800, and 1500 HESW treatment, respectively. Surviving cells in the 400 and 800-treated HESW demonstrated delayed upward growth rate curves, and the 1500 HESW-treated a downward curve. Agar clonogenic efficiencies for surviving cells were 36% (control), 20% (400 HESW), 15% (800 HESW) and 3% (1500 HESW). LLC-WRC256 tumours in Wistar rats were treated once every other day with 1500 HESW on a total of three occasions. Tumours treated with HESW grew more slowly (4.9 cm3) than those in the control (13.5 cm3). HESW fragmented cells and destroyed cell membranes and intracellular organelles. A histological examination of tumours treated with HESW demonstrated local haemorrhage with necrosis in the HESW focus area. Damage to the surrounding skin and soft tissue was slight and transient. These findings suggest that the growth of tumour cells can be suppressed in vitro and in vivo by treatment with HESW.

Shock wave induced endothelial damage--in situ analysis by confocal laser scanning microscopy

For more than a decade, extracorporal shock wave lithotripsy has been a standard clinical method for the treatment of urinary stones. However, side effects that are likely to be correlated to vessel damage can often be observed using noninvasive diagnostic techniques, e.g., magnetic resonance imaging. To avoid side effects it is useful to understand the interaction between shock waves and the vascular system. In particular, this is important in view of new applications like gallstone lithothripsy. In the present study, we exposed human umbilical vessels to electromagnetically generated ultrasound shock waves to analyze subsequent alterations of their endothelial layer. Following en face preparation and fluorescent staining, the endothelium was examined in a confocal laser scanning microscope. Endothelial cells of the shock wave exposed vessels revealed permeabilization of plasma membranes and mitochondrial alterations as potentially lethal damage. An increase in the number of stress fibres may indicate functional changes possibly influencing vessel wall permeability.

In vivo detection of ultrasonically induced cavitation by a fibre-optic technique

The measurement of cavitation events in tissue in vivo would greatly assist us to better understand how pulsed high energy ultrasound (PHEUS) interacts with living tissues, especially with regard to cancer therapy. To accomplish this, we designed and built a fibre-optic hydrophone. The principle was to couple the light of a laser diode into a lightfibre and to register the ultrasound induced modification of the refractive index in tissue. In this manner, the cavitation event could be quantitatively investigated both in water and in vivo. The structure of the bubble dynamic is in reasonable agreement with theoretical predictions, and in vitro measurements. With the fibre-optic set-up, the pressure signal can also be detected. PHEUS was generated by an electromagnetic source adapted from a commercial lithotripter (Lithostar Siemens). As biological tissue we used the experimental R3327-AT1 Dunning prostate tumor growing subcutaneously in the thigh of male Copenhagen rats. The lifetime of the cavitation bubble in water increased with the energy level of the ultrasonic pulse from 250 microseconds at 13 kV capacitor voltage to 750 microseconds at 21 kV, while the lifetime inside the tumor tissue in vivo increased only from 100 microseconds at 13 kV to 220 microseconds at 21 kV capacitor voltage.

Complete local tumor remission after therapy with extra-corporeally applied high-energy shock waves (HESW)

High-energy shock waves (HESW) have recently been proposed as a means of non-invasive tumor therapy. Here we report the first successful local treatment of experimental tumors by means of multifocal and reported application of HESW. The experiments were performed on 29 Syrian golden hamsters bearing amelanotic hamster melanomas in the dorsal skin. HESW, generated electrohydraulically, were applied multifocally to the center and to 5 sites on the margin of the tumors. A group of animals undergoing surgical resection and an untreated group served as controls. Complete remission of local tumor was achieved in more than 90% of the HESW-treated hamsters and in the same number of surgically treated animals, while untreated tumors continued to grow. Frequency of metastasis was the same in both groups after HESW treatment or surgery. Tumor therapy with multifocally and repeatedly applied HESW was thus as successful as surgery.

Ischemia and loss of ATP in tumours following treatment with focused high energy shock waves

High energy shock waves (HESW) have been reported to be cytotoxic to tumour cells in vitro and in vivo. For that reason they are evaluated as a new modality for cancer treatment. In the present study we have quantified the effect of treatment with multifocal HESW on tumour blood flow and energy status. Blood flow and adenosine triphosphate (ATP) concentration were investigated simultaneously in tumour and adjacent tissue of six treated and six untreated amelanotic hamster melanomas (A-Mel-3) at 3, 12 or 24 h after multifocal application of HESW. 14C-iodoantipyrine autoradiography for blood flow measurements and quantitative ATP imaging bioluminescence were employed. Following treatment, tumour blood flow and ATP concentration were significantly reduced, as compared to control, over the entire period of observation. Three hours after HESW, blood flow and ATP concentration were at the background level. In adjacent tissue, blood flow and ATP concentration were distinctly diminished. We therefore conclude that multifocal HESW induce a breakdown of tumour-, and adjacent tissue perfusion which is accompanied by a significant decrease of intracellular ATP concentration.

Determination of the energy-dependent extent of vascular damage caused by high-energy shock waves in an umbilical cord model

To determine the spatial extent of shock-wave-induced vascular damage human umbilical cords were exposed to electromagnetically generated, focused ultrasound waves of different energy densities. During treatment macroscopically visible hematoma and superficial holes appeared. Following exposure specimens were fixed and examined histologically. In addition to vessel wall necrosis and rupture, complete detachment of endothelial cells in defined regions was observed. A correlation of the extent of the damage with the energy density distribution revealed that a local energy density of 0.3 mJ/mm2 is the lower threshold for the occurrence of severe vascular damage.

Shock wave and THP-adriamycin for treatment of rabbit's bladder cancer

Focused high-energy shock waves (6,000 to 10,000 shots) were targeted under ultrasound guidance onto implanted urinary bladder cancer in rabbits to elucidate its effect. Although only focal necrosis of the tumor was seen following 6,000 to 10,000 shots daily for 3 days or following chemotherapy (THP-adriamycin) alone, almost total tumor necrosis was observed following a combined shock-wave therapy for one day and THP-adriamycin administration, demonstrating an additive and/or synergetic effect on rabbit urinary bladder cancer.