Rapid and precise delivery of cells in the urethral sphincter complex by a novel needle‐free waterjet technology

Abstract

Objectives To investigate the therapy of stress urinary incontinence in a preclinical setting cells were injected into the urethrae of minipigs; however, cells injected by William’s needle were frequently misplaced or lost; thus, we investigated if needle‐free cell injections using a novel waterjet technology facilitates precise injections in the urethral sphincter complex. Materials and Methods Porcine adipose tissue‐derived stromal cells (pADSCs) were isolated from boars, expanded, labelled, and injected in the sphincter of female pigs by waterjet employing two different protocols. After incubation for 15 min or 3 days, the urethrae of the pigs were examined. Injected cells were visualised by imaging and fluorescence microscopy of tissue sections. DNA of injected male cells was verified by polymerase chain reaction (PCR) of the sex‐determining region (SRY) gene. Cell injections by William’s needle served as controls. Results The new waterjet technology delivered pADSCs faster and with better on‐site precision than the needle injections. Bleeding during or after waterjet injection or other adverse effects, such as swelling or urinary retention, were not observed. Morphologically intact pADSCs were detected in the urethrae of all pigs treated by waterjet. SRY‐PCR of chromosomal DNA and detection of recombinant green fluorescent protein verified the injection of viable cells. In contrast, three of four pigs injected by William’s needle displayed no or misplaced cells. Conclusion Transurethral injection of viable pADSCs by waterjet is a simple, fast, precise, and yet gentle new technology. This is the first proof‐of‐principle concept study providing evidence that a waterjet injects intact cells exactly in the tissue targeted in a preclinical in vivo situation. To further explore the clinical potential of the waterjet technology longer follow‐up, as well as incontinence models have to be studied.

Large Animal Models for Investigating Cell Therapies of Stress Urinary Incontinence

“…However, this may be compensated by the detection of the recombinant protein by immune fluorescence. [ 43 ]. Recombinant fluorescent labels inherit other significant advantages.…”

“…In our studies female landrace hybrid pigs (fLHP) as well as female Göttingen minipigs (fGMP) were included [ 31 , 34 , 38 , 43 ]. In a small feasibility study using cohorts of 2 or 3 female pigs each, we explored the muscular strength of the urethra of young virgin fLHPs (approx.…”

“…In another series of experiments, porcine adipose-derived stromal cells [ 43 ] or muscle-derived cells (unpublished results) were injected in fLHPs. In such pigs, induction of a transient urethral insufficiency was generated by urethral dilatation and electrocautery about 1–2 cm distal of the bladder neck [ 31 ].…”

Novel Techniques to Improve Precise Cell Injection

“…Moreover, the design of tubing and nozzle had to be adapted again to facilitate penetration of cells through the urothelial cells and connective tissue in or next to the muscular layer of the urethra. In addition, pressure profiles for the injection of cells had to be adjusted as well [41,42].…”

“…Therefore, a fle steerable injector with an angulation function was developed. Moreover, the desi tubing and nozzle had to be adapted again to facilitate penetration of cells throug urothelial cells and connective tissue in or next to the muscular layer of the urethr addition, pressure profiles for the injection of cells had to be adjusted as well [41,42] Figure 7. The prototype of a water-jet cell injector designed for use with a cystoscope.…”