Towards a Treatment of Stress Urinary Incontinence: Application of Mesenchymal Stromal Cells for Regeneration of the Sphincter Muscle

Production of Proliferation- and Differentiation-Competent Porcine Myoblasts for Preclinical Studies in a Porcine Large Animal Model of Muscular Insufficiency

Muscular insufficiency is observed in many conditions after injury, chronic inflammation, and especially in elderly populations. Causative cell therapies for muscle deficiencies are not state of the art. Animal models to study the therapy efficacy are, therefore, needed. We developed an improved protocol to produce myoblasts suitable for pre-clinical muscle therapy studies in a large animal model. Myoblasts were isolated from the striated muscle, expanded by employing five different protocols, and characterized on transcript and protein expression levels to determine procedures that yielded optimized regeneration-competent myoblasts and multi-nucleated myotubes. We report that swine skeletal myoblasts proliferated well under improved conditions without signs of cellular senescence, and expressed significant levels of myogenic markers including Pax7, MyoD1, Myf5, MyoG, Des, Myf6, CD56 (p ≤ 0.05 each). Upon terminal differentiation, myoblasts ceased proliferation and generated multi-nucleated myotubes. Injection of such myoblasts into the urethral sphincter complex of pigs with sphincter muscle insufficiency yielded an enhanced functional regeneration of this muscle (81.54% of initial level) when compared to the spontaneous regeneration in the sham controls without myoblast injection (67.03% of initial level). We conclude that the optimized production of porcine myoblasts yields cells that seem suitable for preclinical studies of cell therapy in a porcine large animal model of muscle insufficiency.

Stress Urinary Incontinence: An Unsolved Clinical Challenge

Stress urinary incontinence is still a frequent problem for women and men, which leads to pronounced impairment of the quality of life and withdrawal from the social environment. Modern diagnostics and therapy improved the situation for individuals affected. But there are still limits, including the correct diagnosis of incontinence and its pathophysiology, as well as the therapeutic algorithms. In most cases, patients are treated with a first-line regimen of drugs, possibly in combination with specific exercises and electrophysiological stimulation. When conservative options are exhausted, minimally invasive surgical therapies are indicated. However, standard surgeries, especially the application of implants, do not pursue any causal therapy. Non-absorbable meshes and ligaments have fallen into disrepute due to complications. In numerous countries, classic techniques such as colposuspension have been revived to avoid implants. Except for tapes in the treatment of stress urinary incontinence in women, the literature on randomized controlled studies is insufficient. This review provides an update on pharmacological and surgical treatment options for stress urinary incontinence; it highlights limitations and formulates wishes for the future from a clinical perspective.

Characterization and In Vitro Cytotoxicity Safety Screening of Fractionated Organosolv Lignin on Diverse Primary Human Cell Types Commonly Used in Tissue Engineering

Simple Summary

As global efforts to use eco-friendly and reusable materials increase, the use of lignin from waste biomass will continue to intensify. Lignin is an underutilized biowaste macromolecule that is gaining considerable interest in biomedical research. However, the source of lignin and the extraction process heavily influence its chemistry, which can influence a cell’s reaction to lignin. Organosolv lignin is extracted via an eco-friendly process from leftover waste material. Few studies have tested the biocompatibility of organosolv lignins with human cells. We extensively characterized fractionated organosolv lignin and performed in vitro cytotoxicity safety screening on diverse primary human cell types commonly used in tissue engineering. This is the first study to show that, at a balanced concentration, fractionated low MW beechwood-derived organosolv lignin is non-cytotoxic to highly relevant human cell types used in tissue engineering including human bone marrow-derived mesenchymal stromal cells (MSCs), chondrocytes, osteoblasts, periodontal ligament fibroblasts, gingival fibroblasts and keratinocytes. Additionally, we show that organosolv lignin can be used to fabricate cell scaffolds and that addition of lignin increased the stiffness and viscosity of the scaffolds as well as cell attachment. This suggests that organosolv lignin may be used in the generation of tissue-like biomaterial-based constructs for tissue repair.

Abstract

There is limited data assessing the cytotoxic effects of organosolv lignin with cells commonly used in tissue engineering. Structural and physico-chemical characterization of fractionated organosolv lignin showed that a decrease of the molecular weight (MW) is accompanied by a less branched conformation of the phenolic biopolymer (higher S/G ratio) and an increased number of aliphatic hydroxyl functionalities. Enabling stronger polymer−solvent interactions, as proven by the Hansen solubility parameter analysis, low MW organosolv lignin (2543 g/mol) is considered to be compatible with common biomaterials. Using low MW lignin, high cell viability (70–100%) was achieved after 2 h, 24 h and 7 days using the following lignin concentrations: MSCs and osteoblasts (0.02 mg/mL), gingival fibroblasts and keratinocytes (0.02 to 0.04 mg/mL), periodontal ligament fibroblasts and chondrocytes (0.02 to 0.08 mg/mL). Cell viability was reduced at higher concentrations, indicating that high concentrations are cytotoxic. Higher cell viability was attained using 30/70 (w/v) NaOH vs. 40/60 (w/v) EtOH as the initial lignin solvent. Hydrogels containing low MW lignin (0.02 to 0.3 mg/mL) in agarose dose-dependently increased chondrocyte attachment (cell viability 84–100%) and hydrogel viscosity and stiffness to 3–11 kPa, similar to the pericellular matrix of chondrocytes. This suggests that low MW organosolv lignin may be used in many tissue engineering fields.

Secretomes of human pluripotent stem cell-derived smooth muscle cell progenitors upregulate extracellular matrix metabolism in the lower urinary tract and vagina

BACKGROUND

Adult mesenchymal stem cells (MSCs) have been studied extensively for regenerative medicine; however, they have limited proliferation in vitro, and the long culture time induces cell senescence. MSCs also contribute to tissue repair through their paracrine function. In this study, we sought to examine the paracrine effects of human smooth muscle cell progenitors (pSMC) on the urethra and adjacent vagina of stress urinary incontinence rodents. We use human pluripotent stem cell (PSC) lines to derive pSMCs to overcome the issue of decreased proliferation in tissue culture and to obtain a homogenous cell population.

METHOD

Three human PSC lines were differentiated into pSMCs. The conditioned medium (CM) from pSMC culture, which contain pSMC secretomes, was harvested. To examine the effect of the CM on the extracellular matrix of the lower urinary tract, human bladder smooth muscle cells (bSMCs) and vaginal fibroblasts were treated with pSMC-CM in vitro. Stress urinary incontinence (SUI) was induced in rats by surgical injury of the urethra and adjacent vagina. SUI rats were treated with pSMC-CM and monitored for 5 weeks. Urethral pressure testing was performed prior to euthanasia, and tissues were harvested for PCR, Western blot, and histological staining. Kruskal-Wallis one-way ANOVA test and Student t test were used for statistical comparisons.

RESULTS

pSMC-CM upregulated MMP-2, TIMP-2, collagen, and elastin gene expression, and MMP-9 activity in the human bladder and vaginal cells consistent with elastin metabolism modulation. pSMC-CM treatment in the SUI rat improved urethral pressure (increase in leak point pressure compared to intact controls, p < 0.05) and increased collagen and elastin expression in the urethra and the adjacent vagina.

CONCLUSION

Conditioned media from smooth muscle cell progenitors derived from human pluripotent stem cells improved urethral leak point pressure and collagen and elastin content in the SUI rat. These findings suggest a novel therapeutic potential for PSC-based treatments for SUI and pelvic floor disorders where tissues are affected by collagen, elastin, and smooth muscle loss.

Feasibility of measuring urethral pressure during female midurethral slings: Case report

RATIONALE

Stress urinary incontinence (SUI) refers to the involuntary leakage of urine when abdominal pressure increases. Midurethral slings (MUS) have become the main surgical method for treating SUI, but no quantitative standard for the degree of sling tightness during operation exists. We achieved this quantitative measurement using ambulatory urodynamic equipment.

PATIENT CONCERNS

A 49-year-old woman presented to our hospital with intermittent urine leakage. Five pads were used daily to keep the vulva dry. The preoperative urethral pressure profilometry (UPP) showed that maximum urethral pressure (MUP) was 54 cmH2O and maximum urethral closure pressure (MUCP) was 53 cmH2O.

DIAGNOSIS

According to the medical history and examination findings, the patient was diagnosed as SUI.

INTERVENTIONS

The MUS and UPP were performed.

OUTCOMES

The intraoperative UPP showed that MUP was 29 cmH2O and MUCP was 17 cmH2O. Three months after the operation, the patient was followed up by telephone. The amount of urine pad usage decreased from 5 pads/d to 0 pads/d, reaching the social control standard (0-1 pads/d). The patient's international consultation on incontinence questionnaire short form score decreased from 18 to 5, and their incontinence quality of life score increased from 12.5 to 78.4. The effect of urine control was satisfactory, and no complications occurred.Five months after operation, the patient was reexamined in the outpatient department. The UPP showed that the MUP was 98 cmH2O and the MUCP was 72 cmH2O. The patient still uses 1 pad/day. The international consultation on incontinence questionnaire short form score is 6 and incontinence quality of life score is 79.5. The curative effect is stable.

LESSONS

MUS has become an effective surgical method for SUI, and the tightness of the sling directly affects the surgical outcome. We have achieved the measurement of urethral pressure during MUS. However, although we found that there is no obvious clinical significance of urethral pressure measurement in MUS operation, future research will benefit from our findings by improving upon our study design to help standardize the clinical diagnosis and treatment of MUS.

Efficiency of mesenchymal stem cells in treatment of urinary incontinence: a systematic review on animal models

AIM

In recent years, the administration of stem cells has been considered a new option for treatment of urinary incontinence (UI). In the present study, the efficiency of mesenchymal stem cell (MSC) transplantation in the treatment of UI was evaluated.

METHODS

Combinations of the key words 'mesenchymal stem cells', 'MSCs', 'urinary incontinence', 'urethral sphincter' and 'involuntary urination' were searched in PubMed and Science Direct databases. Following application of exclusion criteria to the 1946 papers obtained and review and duplicate articles were removed, 23 articles were considered further. The search was limited to the animal model studies.

RESULTS

The data obtained from the evaluation of different studies indicated that the injected MSCs play an important role in the neovascularization and the recovery of muscle cells in UI models through the paracrine process.

CONCLUSION

The obtained data suggested that further trials are needed to be focused on clinical phase of MSC therapy on the patients affected by UI.

Eliminating pulse-induced artifacts in Urethral Pressure data

Urethral Pressure Profilometry (UPP) is a tool in the diagnosis of urinary incontinence. The pressure profile along the urethra is measured by a special catheter in order to assess the contraction strength of the sphincter muscle. The use of microtip catheters with several pressure sensors and an integrated acceleration sensor enables signal reconstruction of the pressure distribution on the urethra's inside. Experimental data from minipigs exhibit artifact patterns in the pressure data. It is shown that these artifacts are caused by vascular pulsation in the sphincter structure. We therefore investigate different methods exploiting the time-correlation of the artifacts to eliminate pulse-induced artifacts in the pressure data without compromising the actual signal. Evaluation of these methods applied to experimental data conclude this work showing that both an Input-Model and Principal Component Analysis Decorrelation are effective at removing the artifacts.

Precise injection of human mesenchymal stromal cells in the urethral sphincter complex of Göttingen minipigs without unspecific bulking effects

AIM

To investigate if injection of cells in the urethral sphincter complex causes unspecific bulking effects.

METHODS

Human mesenchymal stromal cells were isolated, expanded, and characterized. For transurethral injection, cells were labeled with the fluorescent dye PKH26 and in magnetic resonance imaging associated experiments with superparamagnetic particles. Aliquots of cells in 250 µL solvent were injected under vision in the urethral sphincter of immuno-suppressed Göttingen minipigs. Sphincteric closure pressure was recorded by standard and high-definition urethral pressure profilometry prior to and after cell injection. The animals were sacrificed after surgery or after 3 weeks, 3, 6, or 12 months of follow-up. The localisation of the injected cells was explored by histochemistry. Sham-treated animals served as controls.

RESULTS

PKH26-labeled cells survive injections in sphincter tissue samples by Williams cystoscopic injection needle well. In our animal study, the cellular depots were detected in the submucosa or in deeper zones of the sphincter, depending of the length of the injection needle (4-8 mm). Adverse effects associated with injection of cells or solvent such as a noteworthy bleeding, incontinence, or obstruction, were not recorded (n = 96 minipigs). However, a transient infiltration of macrophages was detected 3 weeks after cell injection. Changes in the urethral pressure profiles were not observed in cell-treated (n = 72) compared to sham-treated animals (n = 24).

CONCLUSIONS

Injection of small aliquots of cells to investigate cell therapies in minipigs is a feasible and safe procedure, and it does not bias the intrinsic urethral wall pressure.

Assessing the reproducibility of high definition urethral pressure profilometry and its correlation with an air-charged system

INTRODUCTION

Recently, a new urodynamic method for the assessment of stress urinary incontinence called high definition urethral pressure profilometry (HD-UPP) has been introduced. This method combines a novel microtip catheter with advanced signal processing to enable spatial data location and the reconstruction of a pressure image inside the urethra. In order to assess the reproducibility of HD-UPP data, we statistically evaluate HD-UPP datasets and compare them to data from a double balloon air-charged system.

MATERIALS AND METHODS

Both catheters are used on sedated female minipigs. Data from the microtip catheter are processed through a signal reconstruction algorithm, urodynamic features are extracted, and compared to the air-charged system. Reproducibility of HD-UPP data is assessed by statistically evaluating consecutive, intra-individual datasets.

RESULTS

HD-UPP delivers results in agreement with previous comparisons of microtip and air-charged systems. The average deviation of two consecutive, intra-individual pressure images is very low at 7 cm H₂ O.

CONCLUSIONS

HD-UPP provides physicians with detailed information on the pressure distribution inside the urethra. Through comparison with an air-charged catheter, it is shown that HD-UPP delivers results in agreement with previous studies on the comparison of microtip and air-charged catheters. It provides excellent reproducibility, as the difference between sequentially measured profiles from the same minipig is significantly lower than the one between profiles from different minipigs.

Signal processing in urodynamics: towards high definition urethral pressure profilometry

BACKGROUND

Urethral pressure profilometry (UPP) is used in the diagnosis of stress urinary incontinence (SUI) which is a significant medical, social, and economic problem. Low spatial pressure resolution, common occurrence of artifacts, and uncertainties in data location limit the diagnostic value of UPP. To overcome these limitations, high definition urethral pressure profilometry (HD-UPP) combining enhanced UPP hardware and signal processing algorithms has been developed. In this work, we present the different signal processing steps in HD-UPP and show experimental results from female minipigs.

METHODS

We use a special microtip catheter with high angular pressure resolution and an integrated inclination sensor. Signals from the catheter are filtered and time-correlated artifacts removed. A signal reconstruction algorithm processes pressure data into a detailed pressure image on the urethra's inside. Finally, the pressure distribution on the urethra's outside is calculated through deconvolution. A mathematical model of the urethra is contained in a point-spread-function (PSF) which is identified depending on geometric and material properties of the urethra. We additionally investigate the PSF's frequency response to determine the relevant frequency band for pressure information on the urinary sphincter.

RESULTS

Experimental pressure data are spatially located and processed into high resolution pressure images. Artifacts are successfully removed from data without blurring other details. The pressure distribution on the urethra's outside is reconstructed and compared to the one on the inside. Finally, the pressure images are mapped onto the urethral geometry calculated from inclination and position data to provide an integrated image of pressure distribution, anatomical shape, and location.

CONCLUSIONS

With its advanced sensing capabilities, the novel microtip catheter collects an unprecedented amount of urethral pressure data. Through sequential signal processing steps, physicians are provided with detailed information on the pressure distribution in and around the urethra. Therefore, HD-UPP overcomes many current limitations of conventional UPP and offers the opportunity to evaluate urethral structures, especially the sphincter, in context of the correct anatomical location. This could enable the development of focal therapy approaches in the treatment of SUI.