Damaging effects of high energy shock waves on cultured Madin Darby canine kidney (MDCK) cells

In-vitro cell treatment with focused shockwaves-influence of the experimental setup on the sound field and biological reaction

Background

To improve understanding of shockwave therapy mechanisms, in vitro experiments are conducted and the correlation between cell reaction and shockwave parameters like the maximum pressure or energy density is studied. If the shockwave is not measured in the experimental setup used, it is usually assumed that the device’s shockwave parameters (=manufacturer’s free field measurements) are valid. But this applies only for in vitro setups which do not modify the shockwave, e.g., by reflection or refraction. We hypothesize that most setups used for in vitro shockwave experiments described in the literature influence the sound field significantly so that correlations between the physical parameters and the biological reaction are not valid.

Methods

To reveal the components of common shockwave in vitro setups which mainly influence the sound field, 32 publications with 37 setups used for focused shockwave experiments were reviewed and evaluated regarding cavitation, cell container material, focal sound field size relative to cell model size, and distance between treated cells and air. For further evaluation of the severity of those influences, experiments and calculations were conducted.

Results

In 37 setups, 17 different combinations of coupling, cell container, and cell model are described. The setup used mainly is a transducer coupled via water to a tube filled with a cell suspension. As changes of the shockwaves’ maximum pressure of 11 % can already induce changes of the biological reaction, the sound field and biological reactions are mainly disturbed by use of standard cell containers, use of coupling gel, air within the 5 MPa focal zone, and cell model sizes which are bigger than half the −6 dB focal dimensions.

Conclusions

Until now, correct and sufficient information about the shockwave influencing cells in vitro is only provided in 1 of 32 publications. Based on these findings, guidelines for improved in vitro setups are proposed which help minimize the influence of the setup on the sound field.

Electronic supplementary material

The online version of this article (doi:10.1186/s40349-016-0053-z) contains supplementary material, which is available to authorized users.

Immediate and long-term high levels of plasma homocysteine after extracorporeal shock wave lithotripsy in patients with renal stone disease

BACKGROUND

Plasma homocysteine levels increase in patients with chronic renal failure. Numerous studies have demonstrated that kidney function is one of the most important determinants of plasma total homocysteine (tHcy) concentration. In this study we aimed to evaluate the relationship between tHcy levels and extracorporeal shock wave lithotripsy (ESWL) for patients with renal stones and to see if the change in homocysteine levels continued if renal dysfunction improved.

MATERIALS AND METHODS

The study consisted of 20 patients who underwent first-time ESWL for renal stones. Every patient gave 3 blood samples at 24 h before surgery and at 2 days and at 3 months after ESWL for measurement of plasma levels of tHcy, creatinine, vitamin B6, and vitamin B12.

RESULTS

The 20 patients (12 male, 8 female) had a mean age of 42.8 ± 11.7 years. tHcy levels showed a statistically significant increase from 9.4 ± 1.4 to 18 ± 4.8 and 11.2 ± 2.1 at 2 days and at 3 months, respectively. Serum creatinine also showed a statistically significant increase compared to baseline at 2 days and at 3 months after ESWL.

CONCLUSION

After first-time ESWL, the increase in serum levels of creatinine and tHcy due to renal injury, such as ischemia/reperfusion injury, may be severe and continue for a long period, such as 3 months. According to baseline levels, the increase in homocysteine levels as an indicator of oxidant stress was more severe than the creatinine levels after ESWL for renal stones. Our patients were first-time ESWL patients; however, in patients who undergo EWSL more than once long-term high tHcy levels should also be considered as renal.

Citrate and vitamin E blunt the shock wave-induced free radical surge in an in vitro cell culture model

Free radical formation plays a major role in shock wave lithotripsy induced renal damage. Moreover, previous studies suggest that free radicals may also promote de novo calcium oxalate crystallization of previously damaged urothelium. Citrate is a known inhibitor of renal stone formation and has also been used as a free radical scavenger. Using an in vitro model with Madin-Darby canine kidney (MDCK) cells, we investigated the influence of two free radical scavengers, citrate and vitamin E, on the prevention of the shock wave-induced free radical surge. Suspensions of MDCK cells were placed in containers for shock wave exposure. Six groups of six containers each were examined: (a) no scavengers 0 shocks, (b) no scavengers 100 shocks, (c) citrate 0 shocks, (d) citrate 100 shocks, (e) vitamin E 0 shocks, (f) vitamin E 100 shocks. An unmodified HM3 was used to deliver 100 shocks at 24 kV. The cell groups that were not shocked acted as the control group and were handled identically, except for the lack of shock wave exposure. After shock wave administration, the containers were emptied and cell suspensions were immediately centrifuged. The supernatant was examined for lactate dehydrogenase (LDH) and 8-isoprostane (8-IP), markers of cellular injury and free radical formation, respectively. Intracellular LDH uniformly increased in all groups exposed to shock wave energy. Similarly, 8-IP increased in all shocked groups. However, the 8-IP increase was significantly reduced when the free radical scavengers were employed. As citrate is a well-known inhibitor of calcium nephrolithiasis, its mechanism of action may be further enhanced, based on its ability to reduce free radical formation, by a protective effect on the urothelium. These data further support the use of citrate based medications during the peri-operative period of shock wave lithotripsy, not only to inhibit stone formation and facilitate fragment passage, but also to reduce the incidence of shock wave induced renal damage. Further studies are warranted to clinically test this hypothesis.

Shock waves in vascular diseases: an in-vitro study

Three human aortic specimens were used for this in-vitro study on the effects of shock waves on the arterial wall. Specimen one was from a normal (for age) healthy aorta. The full abdominal length was used (including mesenteric and renal arteries and the aortoiliac bifurcation), divided into six pieces (3 cm). The pieces were placed and fixed into degassed water. Shock waves (SW) were focused onto the aortic wall by means of a B-mode ultrasound imager. An SW generator (Minilith SL1, Storz Medical AG, Kreuzlingen, Switzerland) was used for setting of energy flux density between 0.03 and 0.5 mJ/mm2. The six aortic pieces (excluding piece 1, placed in water and left untreated as control) were treated with SW at increasing energy levels. A second aortic specimen of a man with arteriosclerotic plaques was also used and the experiment repeated at energy levels 1, 5, and 8. Another specimen of normal thoracic aorta was exposed at energy levels 1 and 8 only. Energy levels delivered onto the aortic walls were selected from theoretically destructive levels to minimal levels known not to alter vascular tissues. High-resolution ultrasounds of the aortic segments were performed with a 10 MHz high-resolution, broad-band (ATL 3000, USA) probe in water before and after SW application to detect structural changes in the wall after SW. Histology was performed with a standard hematoxylin-eosin staining.

RESULTS

The aortic pieces did not show macroscopic damages at visual examination, and at the ultrasound examination no visible changes were observed even at higher levels of SW energy. Also no effects were seen by histology. In conclusion, no damaging effects were observed, visually, by ultrasound, or by histology. At these energy levels SW appear to be safe and do not produce any damage to the aortic wall. Therefore, SW could be considered a safe, nondamaging procedure for potential treatment (ie, thrombolysis) in which vessel walls could be involved. Theoretically it is possible that functional changes could be observed in vivo including cell permeability modifications and other alterations (including changes in the potential of the cells in SW fields to modify themselves and to divide). At the energy levels described in this study SW could, theoretically be, safely used for vascular applications (ie, treating venous and arterial thrombi or in arterial plaques modification) without altering major, structural, arterial wall characteristics. Lesions or alterations that have a different density from the normal wall (thrombi or plaques) could be differently sensitive to the same dosage of SW. These differences in acoustic impedance characteristics could be used for potential treatments with SW without damaging the arterial wall.

Allopurinol blocks shock-wave-induced rises in cytosolic calcium levels in MDCK cells

Allopurinol has been reported to ameliorate the side effects in patients following shock wave lithotripsy (SWL); however, the mechanism has not been studied. We have examined the protective effect of allopurinol on Madin-Darby canine kidney (MDCK) cells after shock wave exposure (SWE) by determining the release of aspartate aminotransferase (ASAT) and lactate dehydrogenase (LD), and the resting cytosolic Ca2+ concentration ([Ca2+]i). In SWE-treated cells, the release of ASAT and LD increased immediately, but largely transiently, by approximately 23% and 5-fold over control, respectively. Within 1-6 h after SWE there was a gradual rise in the resting [Ca2+]i of 16-137% above control. Allopurinol did not affect the transient enzyme release but blocked the long-term rises in the resting [Ca2+]i. The transient changes in [Ca2+]i evoked by two hormones, ATP and bradykinin, and a drug that releases Ca2+ from internal Ca2+ stores, thapsigargin, were only slightly affected in allopurinol-treated cells. We conclude that the protection conferred by allopurinol on patients treated with SWL might involve a direct protection of the kidney cells by maintaining a normal resting [Ca2+]i.

Acute bioeffects of electromagnetic lithotripsy

Acute effects of extracorporeal shock wave lithotripsy (ESWL) with Siemens Lithostar on kidney and surrounding tissues were examined on 42 patients with unilateral kidney stones in the Department of Urology, Gazi University, Medical Faculty, Ankara, Türkiye. Radiological examinations were done and 24-h urine and blood samples were obtained a day before, the day after and 30 days after ESWL. Urinary excretion of proteins, glycosaminoglycan, and immunoglobulin G were significantly elevated the day after ESWL. Thirty days after excretion levels of these were statistically insignificant in regard to pretreatment levels. Creatinine clearance of the patients was significantly lowered the day after ESWL. One month later differences were insignificant. Excretory urography detected 12 (29%) kidneys with abnormalities the day after ESWL. Thirty days after only 3 (7%) of the kidneys had persistent abnormalities. The number of abnormalities with ultrasonography 24 h and 30 days after ESWL were 15 (36%) and 5 (12%) respectively. With CT-scanning kidney abnormalities 24 h after and 30 days after ESWL were 24 (57%) and 6 (14%) respectively. There was not any statistically significant difference between patients with either radiological or functional changes after ESWL and with patients without these changes in regard to patient age, sex, stone burden and shock wave number. In conclusion, electromagnetic lithotripsy induces acute renal morphologic and functional changes. Functional changes are transient and subside within a month but although decreasing either in size or number some morphologic changes persist during this period.

Verapamil limits shockwave-induced renal tubular damage in vivo

Previous investigations on Madin Darby Canine Kidney (MDCK) cells demonstrated the protective effect of verapamil against shockwave-induced tubular dysfunction. In the present study, we investigated whether verapamil is also protective against shockwave-induced damage in vivo. Male rates were randomly assigned to three groups: verapamil (N = 18) (Group I), control (N = 18) (Group II), or sham treatment (N = 4) (Group III). Groups I and II were treated with 500 shockwaves to each kidney with the Dornier MFL 5000 at 18 kV. Animals assigned to Group III received only anesthesics. Verapamil was given to the animals in Group I for 5 days starting 1 day before shockwave exposure. Urine was collected for 8 hours the day before and immediately, 1.7, and 28 days after shockwave exposure (SWE) for measurement of volume, osmolality, hemoglobin, protein, N-acetyl-beta-glucosaminidase (NAG), beta 2-microglobulin (beta 2M), sodium, and creatinine. Kidneys were perfused and removed for histologic study 1, 7, and 28 days after SWE in six animals of Groups I and II. Blood was taken in these rats (Day 1 after SWE) for the determination of creatinine and sodium and the calculation of the creatinine clearance (CCr) and the fractional excretion of sodium (FENa). After SWE, there was strong diuresis and significantly increased excretion of NAG and beta 2M in the controls, while urine osmolality decreased. These changes were significantly less pronounced in the verapamil-treated rats. The CCr was higher and FENa lower than in the latter group.(ABSTRACT TRUNCATED AT 250 WORDS)

Tumor growth delay by laser-generated shock waves

The antiproliferative effect of laser-generated shock waves (L-SW) was investigated on a human renal cell carcinoma, RC-8, grown subcutaneously in the nu/nu mouse. The RC-8 is characterized by the syndrome of humoral hypercalcemia of malignancy (HHM) associated with profound cachexia, increase of serum Ca level, hypophosphatemia, and an enhancement of serum parathyroid-like peptides. In this model system, the effects on cachexia and tumor growth were studied after a series of pulses (3-200) generated by a Candela LFDL/3 equipped pulsed-dye laser with optical fiber guided through a hypodermic needle with a 45 degrees angle bended tip, stuck through the skin of the mouse, and positioned directly below the tumor. The antitumor effect, expressed as a delay of tumor growth, was found to be dependent on number of pulses applied, tumor size, and growth rate (alpha). Treatment of RC-8 with alpha = 0.21 was effective only after 200 pulses combined with a tumor volume smaller than 100 mm3. Under these conditions a growth delay of approximately 8 days was observed, paralleled by delay of animal weight loss (cachexia). Under conditions of a decreased growth rate of RC-8 (alpha = 0.13), the susceptibility toward L-SW was found to be increased, expressed by a suppression of tumor growth after 100 pulses. However, no L-SW-associated delay of cachexia was observed under these latter conditions.

Protective effect of verapamil on shock wave induced renal tubular dysfunction

In a prospective randomized study, the effects of the calcium entry blocker verapamil on shock wave induced tubular impairment were examined. A total of 24 patients with renal pelvis or caliceal stones undergoing anesthesia-free extracorporeal shock wave lithotripsy (ESWL*) without auxiliary measures was randomly assigned to the verapamil group (12) or the control group (12). Four doses of verapamil (80 mg. each) were given orally starting the night before ESWL. Controls received no medication. To assess renal tubular function the urinary excretion of alpha 1-microglobulin, N-acetyl-beta-glucosaminidase and Tamm-Horsfall protein were determined before, immediately, and 12 and 24 hours after ESWL. After ESWL there was an increase in urinary alpha 1-microglobulin and N-acetyl-beta-glucosaminidase, which was significantly higher in the control than in the verapamil group. Tamm-Horsfall protein, a glycoprotein synthesized by the distal tubules, decreased significantly less in the verapamil group compared to the controls. Our results indicate that verapamil exhibits a protective effect on shock wave induced tubular damage. The underlying mechanisms are not elucidated yet, and direct actions on tubular cells and interference with renal hemodynamics are to be discussed.

Altered neutrophil permeability following shock wave exposure in vitro

Human neutrophils were exposed to varying numbers of shock waves using the Dornier XL-1 experimental lithotripter. Cellular changes were observed with as few as 60 shock waves generated with 20 KV at a frequency of one per second. A graded reduction in cell numbers and cell viability was observed up to 300 SW. With exposure to 140 SW or above a decrease in mean cell size occurred. When cells were shocked in the presence of adriamycin or after loading with fluorescein, flow cytometry revealed that influx of extracellular components and efflux of cytoplasmic components had occurred. An ultrastructural and functional analysis of cells exposed to 60 SW, where cellular disruption and loss of viability were minimal, revealed several types of cellular changes which may precede SW-induced cell death. Electron microscopic examination revealed in some cells a loss of staining intensity. Plasma membrane rupture and leakage of cytoplasmic components were occasionally evident. The adherence of shocked cells to glass, and the spreading of cells that had adhered, were also reduced. From these studies, it is concluded that cellular permeability and other vital cellular functions in neutrophils are perturbed by SW exposure.

An unusual complication of extracorporeal shock wave lithotripsy: urinoma due to rupture of the renal pelvis

A case of a female patient with urinoma due to rupture of the renal pelvis after extracorporeal shock wave lithotripsy is described. Although temporary perirenal fluid accumulations after extracorporeal shock wave lithotripsy have been reported previously, possibly this is the first case presenting with an abdominal mass due to retroperitoneal urine collection.