Electromotive Drug Administration in the Porcine Renal Pelvis: First Report

Abstract

Introduction:

Electromotive Drug Administration (EMDA) amplifies drug delivery deep into targeted tissues. We tested, for the first time, the ability of EMDA to deliver methylene blue into the urothelium of the renal pelvis.

Materials and Methods:

In an anesthetized female pig, both proximal ureters were transected two inches distal to the ureteropelvic junction. An 8F dual lumen catheter and a 5F fenestrated catheter with an indwelling silver wire were inserted into both renal pelvises following which methylene blue (0.1%) was infused at a rate of 5 mL/min for 20 minutes. In one pelvis, a 4 mA positive pulsed electrical current was applied to the silver wire.

Results:

In contrast to the control pelvis, the EMDA side macroscopically exhibited dense homogeneous staining; microscopy revealed penetration of methylene blue into the urothelium/lamina propria.

Conclusion:

In the porcine renal pelvis, application of EMDA increased the penetration of a charged molecule into the urothelium/lamina propria.

Introduction

Administration of a therapeutic agent directly into the target tissue precludes systemic side effects while providing a higher drug concentration. In urologic cancer, intravesical mitomycin C and Bacille Calmette–Guérin (BCG) are well-known examples of local therapy.^1,2

The urothelium, from the renal pelvis to the proximal urethra, is safeguarded by an intact coating of glycoproteins and proteoglycans (i.e., the glycosaminoglycan [GAG] layer), which prevent the absorption of toxins or waste materials.³ Similarly, the GAG layer prevents the absorption of chemotherapeutic drugs that may be infused locally. A traditional approach to mitigate this barrier is to prolong the contact time between the drug and the urothelial tissue; however, in the urinary tract, this approach leads to drug dilution due to the continuous production of urine throughout the time of drug retention.

Electromotive Drug Administration (EMDA) has been used to overcome the GAG barrier.⁴ In the bladder, EMDA has been demonstrated to be safe and effective; however, its application in the upper urinary tract has not been investigated until recently, when we introduced a proprietary catheter for EMDA application in the ureter.⁵ To comprehensively address the entire upper urinary tract, we sought to expand our ureteral work to investigate the application of EMDA in the renal pelvis.

Materials and Methods

The Institutional Animal Care and Use Committee (IACUC) at the University of California, Irvine, approved this study (UCI-IACUC#AUP-22-118). In a female Yorkshire pig under general anesthesia, a midline incision was made, and the retroperitoneal space was accessed. The proximal ureters were transected two inches distal to the ureteropelvic junction. An 8F double lumen urodynamics catheter and a 24 AWG solid silver wire, which was insulated within a 5F fenestrated catheter, were inserted side-by-side into both renal pelvises. The 5F catheter, along its distal 5 cm, had three rows, 120° apart of 0.3 mL fenestrations. The ureteral tissue around the catheters was secured with a water-tight 2-0 silk suture (Fig. 1). Direct palpation confirmed appropriate catheter position within the renal pelvis. On the EMDA active side, a dispersive pad moistened with conductive gel was securely attached to the flank and connected to the negative electrode of the EMDA generator (Physion^® Mini 30N2, Italy).

FIG. 1.

Diagram illustrating the set-up for EMDA in the renal pelvis. A silver wire insulated within a 5F catheter with distal perforations (fenestrated catheter) and an 8F double-lumen catheter were inserted into each renal pelvis. The surrounding ureteral tissue was secured around the catheters with a 2-0 silk suture. EMDA = electromotive drug administration.

Methylene blue, a positively charged, water-soluble, and traceable substance with a molecular weight of 334D at a concentration of 0.1%, was infused into both ureters at a rate of 5 mL/min for 20 minutes. The infusion was done through one lumen of the dual-lumen catheters using a drug infusion pump (BYS-820 Changsha, China). The second lumen of the 8F catheter was used for gravity drainage. Simultaneously, in the EMDA active pelvis, a positive pulsed electrical current of 4 mA was applied through the silver wire 5F catheter for 20 minutes. In the EMDA-control renal pelvis, the silver wire was not activated. Following the infusion, the pig was euthanized, and both kidneys were excised and longitudinally opened. Photographs were taken, and the specimens were placed in liquid nitrogen for subsequent histopathological analysis.

Given that saturation refers to the intensity of color in an image, a quantitative color saturation analysis of each digital photograph was performed. In comparing EMDA activated and non-EMDA activated photographs, RGB hex codes were obtained with a color picker from random blue pixels. The hex code was then converted with an online program (https://www.rapidtables.com/convert/color/rgb-to-hsv.html) to a Hue Saturation Value to obtain the saturation of the blue pixel. A paired t-test was performed to analyze the difference between blue saturation in EMDA-activated and non-EMDA-activated photographs to assess the density of methylene blue penetration in the urothelial tissue.

Results

Macroscopically, the EMDA-active renal pelvis exhibited dense and homogenous blue staining of the urothelium (Fig. 2-A1). The EMDA-control renal pelvis exhibited scant staining (Fig. 2-B1). Microscopically, slight denudation of the urothelial cells was observed in both experimental and control pelvises, which were attributed to the freezing process used for tissue preservation (Fig. 2-A2, B2, respectively). No injury was present in the deeper tissues. The EMDA-active renal pelvis revealed a dense and diffuse penetration of methylene blue into the urothelium and the lamina propria (Fig. 2-A3, A4). In contrast, the EMDA-control pelvis showed faint methylene blue staining of the urothelium with minimal penetration into the lamina propria (Fig. 2-B3, B4). As displayed in Table 1, quantitative color saturation analysis of digital pathology photographs revealed the blue in Figure 2-A1 was significantly more saturated than the blue in Figure 2-B1 (96.6 vs 44.8, p = 0.0020). Furthermore, the blue in Figure 2-A4 was significantly more saturated than the blue in Figure 2-B4 (92.0 vs 38.4, p = 0.0003).

FIG. 2.

Macroscopic and microscopic image of EMDA active (A) and EMDA control infusion of methylene blue into the porcine kidney (B). (A1) Macroscopic photographs with intense staining of the renal pelvis. (A2) H&E staining shows a normal architecture with no signs of acute injury. (A3, A4) H&E staining shows deep blue staining of urothelium and the lamina propria. (B1) Faint staining of the renal pelvis. (B2) H&E staining shows a normal architecture. (B3, B4) Patchy blue staining of urothelium scant penetration of methylene blue into the lamina propria. H&E = hematoxylin and eosin.

Table 1.

Blue Saturation of Random Blue Pixels Within Figure 2 —A1, B1, A4, and B4 as Determined by Their Digital RGB Hex Code Converted to Hue Saturation Value

A1 saturation value (macroscopic photo with EMDA)	B1 saturation value (macroscopic photo without EMDA)	A4 saturation Value (microscopic photo with EMDA)	B4 saturation value (microscopic photo without EMDA)
100	28	93	37
99	42	91	28
97	44	89	28
93	66	98	61
94	44	89	38

EMDA = electromotive drug administration.

Discussion

In this initial pilot study, the application of EMDA facilitated widespread and substantial penetration of methylene blue into the urothelium and lamina propria of the porcine renal pelvis. These findings are similar to our earlier work using EMDA application in the ureter.⁵ The ureteral EMDA work is now in its second phase as we are studying the impact of EMDA during infusion of a variety of drugs associated with ureteral relaxation with a goal of acutely relaxing the ureter to enable safe passage of 16F and possibly larger, ureteral access sheaths during ureteroscopic stone procedures.

In the field of urology, EMDA has primarily been focused on the bladder. EMDA uses several mechanisms to deliver drug deep into the bladder's urothelium: electromigration, electro-osmosis, and electroporation.⁶ Studies have shown that EMDA application in the bladder improves intravesical drug administration for a range of conditions, including nonmuscle-invasive bladder cancer (mitomycin C⁷), neurogenic and nonneurogenic overactive bladder (oxybutinyn,⁸ lidocaine/dexamethasone/epinephrine⁹ and botulinium toxin¹⁰), radiation and chronic cystitis (hyaluronic acid¹¹ and lidocaine/dexamethasone¹²), and as a preanesthesia technique before transurethral urological procedures (lignocaine and epinephrine).^13,14 More specifically, in both laboratory and clinical investigations, the application of EMDA in the urothelial-lined bladder has enhanced the uptake of chemotherapeutic agents. Randomized controlled trials showed that in addition to being feasible and safe, intravesical EMDA/mitomycin C administration before transurethral resection of bladder tumors reduced recurrence rates and improved disease-free intervals compared with intravesical passive infusion of mitomycin C.^7,15

Upper-tract urothelial carcinoma (UTUC) is 10–20-fold less common than in the bladder; however, it commonly leads to a nephron reducing, nephroureterectomy.^16,17 Over the past score, due to advances in endourological techniques and equipment, nephron-sparing surgery has become a viable treatment option for low-risk UTUC. In addition to maintaining favorable oncological outcomes, this approach preserves the ipsilateral kidney.^18,19 A major drawback of the endourological approach is the frequent recurrence of tumor necessitating additional surveillance and therapeutic procedures.

Similar to bladder cancer, in an effort to reduce the risk of recurrence and progression following nephron-sparing UTUC surgery, a range of agents, such as locally administered mitomycin C, have been employed. This approach has shown promising intermediate-term benefits with regard to recurrence, progression, and nephroureterectomy-free survival.²⁰ Unfortunately, in contrast to the bladder, where the agent has prolonged contact with the urothelium, the upper urinary tract is only briefly exposed due to the continuous flow of urine toward the bladder.

One solution has been the development of a mitomycin C-containing product (Jelmyto^®), which at room temperature exists as a liquid that can be infused via a ureteral catheter; however, at body temperature, the infused material rapidly transforms into a gel, thereby providing an extended period of urothelial contact. In an open-label, phase 3 trial from 24 academic centers of patients with primary or recurrent biopsy-proven, low-grade upper tract urothelial cancer treated with Jelmyto, a complete response was observed in 59% of patients at a median follow-up of 11 months. These sanguine results were counterbalanced by a high rate of complications: ureteral stenosis (44%), urinary tract infection (32%), hematuria (31%), and flank pain (30%).²¹

Our investigation focused on exploring the utilization of EMDA in the renal pelvis, with the aim of overcoming the rapid outflow of any infused drug and breaching the GAG layer. Accordingly, given the positive outcome of our prior work with ureteral EMDA,⁵ we proceeded to investigate the efficacy of EMDA in the renal pelvis. A current density of 0.5 mA/cm² was applied based on ex vivo measurements of the surface area of the renal pelvis in four pig kidneys, the mean of which was 8 cm.² We multiplied the surface area by 0.5 mA/cm to determine the 4 mA current applied in this study.

To ensure consistent drug delivery to the renal pelvis and prevent backflow, a double-lumen urodynamics catheter with one line for gravity drainage was utilized in conjunction with a drug infusion pump at 5 mL/min. This approach maintained a steady and controlled administration of the methylene blue. Given the small size of the porcine renal pelvis and the use of a large dispersive pad (11.5″ × 7.5″) affixed to the pig's flank, we anticipated a more uniform penetration of the drug than occurs with EMDA in the bladder, where the current density is higher along the anterior wall of the bladder due to the abdominal placement of the dispersive electrode.²²

The findings from this study, along with our previous research on the impact of EMDA in the ureter, demonstrate that EMDA may serve as a novel method for enhanced drug delivery to the urothelium and lamina propria of the upper urinary tract.⁵ EMDA facilitates the uninterrupted and expedited transportation of drugs, offering a potential platform for enhanced local drug administration. The possible applications of EMDA in the urinary upper tract include infusion of chemotherapeutic agents, smooth muscle relaxants, antibiotics, and anti-inflammatory agents.²³ Clearly, much work in this regard remains to be completed. Presently, having obtained approval from the UCI-IACUC, we are proceeding to examine the effectiveness of EMDA in augmenting the penetration of mitomycin C in the upper urinary tract.

There are several limitations to this initial report of EMDA in the renal pelvis. Notably, as this is a pilot study, there are multiple aspects yet to be explored regarding the mechanics of EMDA in the ureter and renal pelvis. Specifically, the performance of EMDA is influenced by several parameters, such as pH, current density, mode of current delivery (pulsed vs direct), and the molecular weight and ionic strength of the infused substance.²⁴ As such, we need to define the optimum settings for the application of EMDA in the renal pelvis, specifically for the infusion of mitomycin C or any other therapeutic substance. Further, this is an acute study, and a long-term evaluation is needed to determine any potential negative effects of EMDA in the upper urinary tract and to assess the duration of drug retention as well as the stability of the drug when subjected to an electrical current.

Conclusion

Building upon our previous investigation of EMDA in the ureter, we expanded its application to the renal pelvis. EMDA application in the renal pelvis resulted in a dense, diffuse, and homogenous penetration of methylene blue throughout the urothelium and lamina propria without any acute adverse side effects. This finding suggests that EMDA could potentially serve as a new avenue for effective local drug distribution in the upper urinary tract.

Footnotes

Acknowledgments

The authors would like to thank Dr. Elias Wehbi for his sage advice and assistance with the development of this study.

Authors' Contributions

S.H.H.S., Y.X.W., and Z.E.T. conceived and designed the study, collected and analyzed data, and drafted the manuscript. S.A.M.L., S.S., and P.P. conducted experiments and gathered and processed data. M.N. contributed the histopathology preparation and interpretation of the renal pelvis samples. B.M.G. contributed to data interpretation, manuscript preparation, and revision. S.N.A., P.J., R.M.P., J.L., and R.V.C. provided critical guidance and oversight throughout the research process, including study design, data analysis, and manuscript revision. In addition, secured funding for the project and contributed to the project's conceptualization. All authors have reviewed and approved the final version of the article.

Author Disclosure Statement

No competing financial interests exist.

Funding Information

Support for this study came from unrestricted funds in the University of California, Irvine—Department of Urology's Curiosity and Innovation Laboratory.

Abbreviations Used

References

Schmidt

, Kunath

, Coles

, et al. Intravesical Bacillus Calmette-Guérin versus mitomycin C for Ta and T1 bladder cancer. Cochrane Database Syst Rev, 2020; 1(1):CD011935; doi: 10.1002/14651858.CD011935.PUB2

Roumiguié

, Kamat

, Bivalacqua

, et al. International Bladder Cancer Group Consensus Statement on Clinical Trial Design for Patients with Bacillus Calmette-Guérin-exposed high-risk non-muscle-invasive bladder cancer. Eur Urol, 2022; 82(1):34–46; doi: 10.1016/J.EURURO.2021.12.005

Klingler

. Glycosaminoglycans: How much do we know about their role in the bladder?. Urologia, 2016; 83 Suppl 1:11–14; doi: 10.5301/URO.5000184

Racioppi

, DI Gianfrancesco

, Ragonese

, et al. ElectroMotive drug administration (EMDA) of Mitomycin C as first-line salvage therapy in high risk “BCG failure” non muscle invasive bladder cancer: 3 Years follow-up outcomes. BMC Cancer, 2018; 18(1):1224; doi: 10.1186/S12885-018-5134-7

Sharifi

SHH

, Ali

, Wu

, et al. Electromotive Drug Administration in the ureter in an in vivo animal model: Initial report. J Endourol, 2023; 37(7):823–827; doi: 10.1089/END.2023.0026

Min

JWS

, Saeed

, Coene

, et al. Electromotive Enhanced Drug Administration in Oncology: Principles, evidence, current and emerging applications. Cancers (Basel), 2022; 14(20):4980; doi: 10.3390/CANCERS14204980

Jung

, Gudeloglu

, Kiziloz

, et al. Intravesical electromotive drug administration for non-muscle invasive bladder cancer. Cochrane Database Syst Rev, 2017; 9(9):CD011864; doi: 10.1002/14651858.CD011864.PUB2

Di Stasi

, Giannantoni

, Vespasiani

, et al. Intravesical electromotive administration of oxybutynin in patients with detrusor hyperreflexia unresponsive to standard anticholinergic regimens. J Urol, 2001; 165(2):491–498; doi: 10.1097/00005392-200102000-00032

Gauruder-Burmester

, Biskupskie

, Rosahl

, et al. Electromotive drug administration for treatment of therapy-refractory overactive bladder. Int Braz J Urol, 2008; 34(6):758–764; doi: 10.1590/S1677-55382008000600011

10.

Ladi-Seyedian

, Sharifi-Rad

, Kajbafzadeh

. Intravesical electromotive botulinum toxin type “A” administration for management of urinary incontinence secondary to neuropathic detrusor overactivity in children: Long-term follow-up. Urology, 2018; 114:167–174; doi: 10.1016/J.UROLOGY.2017.11.039

11.

Gülpinar Ö, Haliloělu

, Gökce

, et al. Instillation of hyaluronic acid via electromotive drug administration can improve the efficacy of treatment in patients with interstitial cystitis/painful bladder syndrome: A Randomized Prospective Study. Korean J Urol, 2014; 55(5):354–359; doi: 10.4111/KJU.2014.55.5.354

12.

Riedl

, Knoll

, Plas

, et al. Intravesical electromotive drug administration for the treatment of non-infectious chronic cystitis. Int Urogynecol J Pelvic Floor Dysfunct, 1997; 8(3):134–137; doi: 10.1007/BF02764844

13.

Fontanella

, Rossi

, Stephen

. Bladder and urethral anaesthesia with electromotive drug administration (EMDA): A technique for invasive endoscopic procedures. Br J Urol, 1997; 79(3):414–420; doi: 10.1046/j.1464-410x.1997.32419.x

14.

Hashemi

, Sahai

, Malde

. Applications of electromotive drug administration in urology. Urol Ann, 2020; 12(4):301–308; doi: 10.4103/UA.UA_152_19

15.

Di Stasi

, Valenti

, Verri

, et al. Electromotive instillation of mitomycin immediately before transurethral resection for patients with primary urothelial non-muscle invasive bladder cancer: A randomised controlled trial. Lancet Oncol, 2011; 12(9):871–879; doi: 10.1016/S1470-2045(11)70190-5

16.

Soria

, Shariat

, Lerner

, et al. Epidemiology, diagnosis, preoperative evaluation and prognostic assessment of upper-tract urothelial carcinoma (UTUC). World J Urol, 2017; 35(3):379–387; doi: 10.1007/S00345-016-1928-X

17.

Raman

, Messer

, Sielatycki

, et al. Incidence and survival of patients with carcinoma of the ureter and renal pelvis in the USA, 1973–2005. BJU Int, 2011; 107(7):1059–1064; doi: 10.1111/J.1464-410X.2010.09675.X

18.

Rouprêt

, Babjuk

, Compérat

, et al. European Association of Urology Guidelines on upper urinary tract urothelial carcinoma: 2017 Update. Eur Urol, 2018; 73(1):111–122; doi: 10.1016/J.EURURO.2017.07.036

19.

Margulis

, Shariat

, Matin

, et al. Outcomes of radical nephroureterectomy: A series from the Upper Tract Urothelial Carcinoma Collaboration. Cancer, 2009; 115(6):1224–1233; doi: 10.1002/CNCR.24135

20.

Metcalfe

, Wagenheim

, Xiao

, et al. Induction and maintenance adjuvant mitomycin C topical therapy for upper tract urothelial carcinoma: Tolerability and intermediate term outcomes. J Endourol, 2017; 31(9):946–953; doi: 10.1089/END.2016.0871

21.

Kleinmann

, Matin

, Pierorazio

, et al. Primary chemoablation of low-grade upper tract urothelial carcinoma using UGN-101, a mitomycin-containing reverse thermal gel (OLYMPUS): An open-label, single-arm, phase 3 trial. Lancet Oncol, 2020; 21(6):776–785; doi: 10.1016/S1470-2045(20)30147-9

22.

Kos

, Vásquez

, Miklavčĭ

, et al. Investigation of the mechanisms of action behind Electromotive Drug Administration (EMDA). PeerJ, 2016; 4(8):2309; doi: 10.7717/PEERJ.2309

23.

Rosamilia

, Dwyer

, Gibson

. Electromotive drug administration of lidocaine and dexamethasone followed by cystodistension in women with interstitial cystitis. Int Urogynecol J Pelvic Floor Dysfunct, 1997; 8(3):142–145; doi: 10.1007/BF02764846

24.

Slater

, Patel

, Viney

, et al. The effects and effectiveness of electromotive drug administration and chemohyperthermia for treating non-muscle invasive bladder cancer. Ann R Coll Surg Engl, 2014; 96(6):415–419; doi: 10.1308/003588414X13946184901001