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.

Mesenchymal stem cells (MSC) are known for their vascular regeneration capacity by neoangiogenesis. Even though, several delivery approaches exist, particularly in the case of intravascular delivery, only limited number of cells reach the targeted tissue and are not able to remain on site. Applicated cells exhibit poor survival accompanied with a loss of functionality. Moreover, cell application techniques lead to cell death and impede the overall MSC function and survival. 3D cell spheroids mimic the physiological microenvironment, thus, overcoming these limitations. Therefore, in this study we aimed to evaluate and assess the feasibility of 3D MSCs spheroids for endovascular application, for treatment of ischemic peripheral vascular pathologies. Multicellular 3D MSC spheroids were generated at different cell seeding densities, labelled with ultra-small particles of iron oxide (USPIO) and investigated in vitro in terms of morphology, size distribution, mechanical stability as well as ex vivo with magnetic resonance imaging (MRI) to assess their trackability and distribution. Generated 3D spheroids were stable, viable, maintained stem cell phenotype and were easily trackable and visualized via MRI. MSC 3D spheroids are suitable candidates for endovascular delivery approaches in the context of ischemic peripheral vascular pathologies.

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