Reduction of Overactive Bladder Medications in Spinal Cord Injury With Self-Administered Neuromodulation; a Randomized Trial.

PURPOSE: To evaluate if self-administered bladder neuromodulation with transcutaneous tibial nerve stimulation can safely replace overactive bladder medications in people with spinal cord injury. MATERIALS AND METHODS: We performed a 3-month, randomized, investigator-blinded, tibial nerve stimulation vs sham-control trial in adults with spinal cord injury and neurogenic bladder performing intermittent catheterization and taking overactive bladder medications. The primary outcome was a reduction in bladder medications while maintaining stable bladder symptoms and quality of life based on pre-post Neurogenic Bladder Symptom Score and the Incontinence-QOL questionnaire, respectively. Secondary outcomes included changes in pre-post cystometrogram, 2-day voiding diaries, and an anticholinergic medication side effect survey. RESULTS: Fifty people consented to the study, with 42 completing the trial. No dropouts were due to stimulation issues. All baseline demographics and surveys were comparable at baseline. Cystometrogram parameters were also comparable at baseline, except the stimulation group had a higher proportion of loss of bladder compliance compared to the control group. At the end of the trial, a significantly greater percentage of the tibial nerve stimulation group were able to reduce medications (95% v 68%), by a 26.2% difference in medication reduction (95% confidence interval 1.17%-51.2%). Function and quality of life surveys and cystometrograms at the end of the trial were alike between groups. Transcutaneous tibial nerve stimulation satisfaction surveys and adherence to protocol were high. CONCLUSIONS: In people with chronic spinal cord injury performing intermittent catheterization, transcutaneous tibial nerve stimulation can be an option to reduce or replace overactive bladder medications.

Cerebellar functional connectivity relates to lower urinary tract function: A 7 Tesla study.

OBJECTIVES: The objective of this study is to explore the functional connectivity (FC) of the cerebellum during the storage phase of micturition, through detecting spontaneous blood-oxygen-level dependent signal between the cerebellum and different brain regions using a high-resolution 7 Tesla magnetic resonance imaging (MRI) scanner. MATERIALS AND METHODS: We recruited healthy individuals with no reported history of neurological disease or lower urinary tract (LUT) symptoms. Participants were asked to drink 500 mL of water and then empty their bladders before entering the MRI scanner. They underwent a T1-weighted anatomical scan, followed by an initial (8 min) empty bladder resting state functional MRI (rs-fMRI) acquisition. Once subjects felt the desire to void, a second rs-fMRI scan was obtained, this time with a full bladder state. We established a priori cerebellar regions of interest from the literature to perform seed-to-voxel analysis using nonparametric statistics based on the Threshold Free Cluster Enhancement method and utilized a voxel threshold of p < 0.05. RESULTS: Twenty individuals (10 male and 10 female) with a median age of 25 years (IQR [3.5]) participated in the study. We placed 31 different 4-mm spherical seeds throughout the cerebellum and assessed their FC with the remainder of the brain. Three of these (left cerebellar tonsil, right posterolateral lobe, right posterior lobe) showed significant differences in connectivity when comparing scans conducted with a full bladder to those with an empty bladder. Additionally, we observed sex differences in FC, with connectivity being higher in women during the empty bladder condition. CONCLUSION: Our initial findings reveal, for the first time, that the connectivity of the cerebellar network is modulated by bladder filling and is associated with LUT function. Unraveling the cerebellum's role in bladder function lays the foundation for a more comprehensive understanding of urinary pathologies affecting this area.

Conception and implementation of an MRI-compatible device to elicit the bulbocavernosus reflex for an open spinal cord study.

OBJECTIVE: Functional MRI (fMRI) can be employed to assess neuronal activity in the central nervous system. However, investigating the spinal cord using fMRI poses several technical difficulties. Enhancing the fMRI signal intensity in the spinal cord can improve the visualization and analysis of different neural pathways, particularly those involved in bladder function. The bulbocavernosus reflex (BCR) is an excellent method for evaluating the integrity of the sacral spinal cord. Instead of stimulating the glans penis or clitoris, the BCR can be simulated comfortably by tapping the suprapubic region. In this study, we explain the necessity and development of a device to elicit the simulated BCR (sBCR) via suprapubic tapping while conducting an fMRI scan. METHODS: The device was successfully tested on a group of 20 healthy individuals. Two stimulation task block protocols were administered (empty vs. full bladder). Each block consisted of 40 s of suprapubic tapping followed by 40 s of rest, and the entire sequence was repeated four times. RESULTS: Our device can reliably and consistently elicit sBCR noninvasively as demonstrated by electromyographic recording of pelvic muscles and anal winking. Participants did note mild to moderate discomfort and urge to void during the full bladder task. CONCLUSION: Our device demonstrates an efficacious approach to elicit sBCR within an MRI bore to assess sacral spinal cord functional activity without generating any significant motion artifacts. SIGNIFICANCE: This device can explore the mechanisms and processes controlling urinary, digestive, or sexual function within this region in humans.

Evaluating noninvasive brain stimulation to treat overactive bladder in individuals with multiple sclerosis: a randomized controlled trial protocol.

BACKGROUND: Multiple Sclerosis (MS) is an often debilitating disease affecting the myelin sheath that encompasses neurons. It can be accompanied by a myriad of pathologies and adverse effects such as neurogenic lower urinary tract dysfunction (NLUTD). Current treatment modalities for resolving NLUTD focus mainly on alleviating symptoms while the source of the discomfort emanates from a disruption in brain to bladder neural circuitry. Here, we leverage functional magnetic resonance imaging (fMRI), repetitive transcranial magnetic stimulation (rTMS) protocols and the brains innate neural plasticity to aid in resolving overactive bladder (OAB) symptoms associated with NLUTD. METHODS: By employing an advanced neuro-navigation technique along with processed fMRI and diffusion tensor imaging data to help locate specific targets in each participant brain, we are able to deliver tailored neuromodulation protocols and affect either an excitatory (20 min @ 10 Hz, applied to the lateral and medial pre-frontal cortex) or inhibitory (20 min @ 1 Hz, applied to the pelvic supplemental motor area) signal on neural circuitry fundamental to the micturition cycle in humans to restore or reroute autonomic and sensorimotor activity between the brain and bladder. Through a regimen of questionnaires, bladder diaries, stimulation sessions and analysis, we aim to gauge rTMS effectiveness in women with clinically stable MS. DISCUSSION: Some limitations do exist with this study. In targeting the MS population, the stochastic nature of MS in general highlights difficulties in recruiting enough participants with similar symptomology to make meaningful comparisons. As well, for this neuromodulatory approach to achieve some rate of success, there must be enough intact white matter in specific brain regions to receive effective stimulation. While we understand that our results will represent only a subset of the MS community, we are confident that we will accomplish our goal of increasing the quality of life for those burdened with MS and NLUTD. TRIAL REGISTRATION: This trial is registered at ClinicalTrials.gov (NCT06072703), posted on Oct 10, 2023.

Noninvasive brain stimulation in the treatment of functional urological and pelvic floor disorders: A scoping review.

INTRODUCTION: Functional pelvic floor disorders (PFD) such as bowel and bladder dysfunctions can be challenging to manage with our current therapeutic modalities. Recently, noninvasive brain stimulation has emerged as a novel strategy for noninvasive pelvic floor management. Here, we assessed the current state of research on this topic. METHODS: A scoping review was conducted with Pubmed, Web of Science, and Embase, in conjunction with clinicaltrials.gov, encompassing all manuscripts published without past time limit up until June 30, 2022. RESULTS: Of the 880 abstracts identified in a blind selection by two reviewers, 14 publications with an evidence level of 1 or 2 (Oxford scale) were eligible and included in this review. Review articles, case reports (<5 patients), letters, and protocol studies were excluded. PFDs were described as either pelvic pain or lower urinary tracts symptoms (LUTS) with repeated transcranial magnetic stimulation (rTMS) as the most common treatment modality. Despite heterogeneous therapeutic protocols, significant improvements were observed such as reduction in postvoid residual of urine, increased bladder capacity, improved voiding flow paraments, and decreased chronic pelvic, and bladder pain. No appreciable adverse effects were noted. However, low sample populations allowed only provisional conclusions. CONCLUSION: Noninvasive transcranial neurostimulation for LUTS and pelvic pain is emerging as an effective tool for clinicians to utilize in the future. Further investigation is needed to elucidate the full significance of the indicated outcomes.

Disruption of specific white matter tracts is associated with neurogenic lower urinary tract dysfunction in women with multiple sclerosis.

OBJECTIVE: To identify specific white matter tracts (WMTs) whose disruption is associated with the severity of neurogenic lower urinary tract dysfunction (NLUTD) in two independent cohorts of women with multiple sclerosis (MS) and NLUTD. METHODS: Cohort 1 consisted of twenty-eight women with MS and NLUTD. The validation cohort consisted of 10 women with MS and NLUTD. Eleven healthy women served as controls. Participants of both MS cohorts had the same inclusion and exclusion criteria. Both MS cohorts and the healthy controls underwent the same clinical assessment and functional MRI (fMRI) protocol, except that the validation MS cohort underwent 7-Tesla fMRI scan. Fifteen WMTs (six coursing to relevant brainstem areas) involved in bladder control were a priori regions of interest (ROI). Spearman's correlation test was performed between each the Fractional Anisotropy (FA) and mean diffusivity (MD) of each WMT and the clinical parameters. RESULTS: Overall, we found a very high degree of overlap (100% of a priori ROI) in the tracts identified by our correlation analysis as having the greatest contribution to NLUTD symptoms in MS women. The right inferior cerebellar peduncle, left posterior limb of internal capsule, and left superior cerebellar peduncle displayed significant associations to the greatest number of clinical parameters. CONCLUSIONS: Our correlation analysis supports the role of specific WMT disruptions in the contribution of symptoms in women with MS and NLUTD, as confirmed in two independent MS cohorts.

Quantification of Myelinated Nerve Fraction and Degeneration in Spinal Cord Neuropil by SHIFT MRI.

BACKGROUND: Neurodegeneration is a complex cellular process linked to prompt changes in myelin integrity and gradual neuron loss. Current imaging techniques offer estimations of myelin volumes in lesions/remyelinated areas but are limited to detect subtle injury. PURPOSE: To investigate whether measurements detected by a signal hierarchically isolated as a function of time-to-echo (SHIFT) MRI technique can determine changes in myelin integrity and fiber axolemma. STUDY TYPE: Prospective animal model. ANIMAL MODEL: Surgically demyelinated spinal cord (SC) injury model in rodents (n = 6). FIELD STRENGTH/SEQUENCE: Gradient-echo spin-echo at 3T. ASSESSMENT: Multicompartment T2 relaxations were computed by SHIFT MRI in 75-microns-resolution images of the SC injury penumbra region 2 weeks post-trauma. G-ratio and axolemma delamination were assessed by transmission electron microscopy (TEM) in intact and injured samples. SC myelinated nerve fraction was computed by SHIFT MRI prospectively and assessed histologically. STATISTICAL TESTS: Relations between SHIFT-isolated T2 -components and TEM measurements were studied using linear regression and t-tests. Pearson's correlation and significance were computed to determine the SHIFT's sensitivity to detect myelinated fibers ratio in gray matter. Regularized least-squares-based ranking analysis was employed to determine SHIFT MRI's ability to discern intact and injured myelinated nerves. RESULTS: Biexponential signals isolated by SHIFT MRI for intact vs. lesion penumbra exhibited changes in T2 , shifting from intermediate components (25 ± 2 msec) to long (43 ± 11 msec) in white matter, and similarly in gray matter regions-of-interest (31 ± 2 to 46 ± 16 msec). These changes correlated highly with TEM g-ratio and axon delamination measurements (P < 0.05). Changes in short T2 components were observed but not statistically significant (8.5 ± 0.5 to 7 ± 3 msec, P = 0.445, and 4.0 ± 0.9 to 7 ± 3 msec, P = 0.075, respectively). SHIFT MRI's ability to detect myelinated fibers within gray matter was confirmed (P < 0.001). DATA CONCLUSION: Changes detected by SHIFT MRI are associated with abnormal intermembrane spaces formed upon mild injury, directly correlated with early neuro integrity loss. Level of Evidence 1 Technical Efficacy Stage 2.

Modulatory effects of intravesical P2X2/3 purinergic receptor inhibition on lower urinary tract electromyographic properties and voiding function of female rats with moderate or severe spinal cord injury.

OBJECTIVES: To evaluate the role that intravesical P2X2/3 purinergic receptors (P2X2/3Rs) play in early and advanced neurogenic lower urinary tract (LUT) dysfunction after contusion spinal cord injury (SCI) in female rats. MATERIALS AND METHODS: Female Sprague-Dawley rats received a thoracic Th8/Th9 spinal cord contusion with either force of 100 kDy (cN); moderate) or 150 kDy (cN; severe); Sham rats had no injury. Evaluations on urethane-anesthetised rats were conducted at either 2 or 4 weeks after SCI. LUT electrical signals and changes in bladder pressure were simultaneously recorded using cystometry and a set of custom-made flexible microelectrodes, before and after intravesical application of the P2X2/3R antagonist AF-353 (10 µM), to determine the contribution of P2X2/3R-mediated LUT modulation. RESULTS: Severe SCI significantly increased bladder contraction frequency, and reduced both bladder pressure amplitude and intraluminal-pressure high-frequency oscillations (IPHFO). Intravesical P2X2/3R inhibition did not modify bladder pressure or IPHFO in the Sham and moderate-SCI rats, although did increase the intercontractile interval (ICI). At 2 weeks after SCI, the Sham and moderate-SCI rats had significant LUT electromyographic activity during voiding, with a noticeable reduction in LUT electrical signals seen at 4 weeks after SCI. Intravesical inhibition of P2X2/3R increased the ICI in the Sham and moderate-SCI rats at both time-points, but had no effect on rats with severe SCI. The external urethral sphincter (EUS) showed strong and P2X2/3R-independent electrical signals in the Sham and moderate-SCI rats in the early SCI stage. At 4 weeks after SCI, the responsiveness of the EUS was significantly attenuated, independently of SCI intensity. CONCLUSIONS: This study shows that electrophysiological properties of the LUT are progressively impaired depending on SCI intensity and that intravesical P2X2/3R inhibition can attenuate electrical activity in the neurogenic LUT at early, but not at semi-chronic SCI. This translational study should be useful for planning clinical evaluations.

Detection and Monitoring of Microparticles Under Skin by Optical Coherence Tomography as an Approach to Continuous Glucose Sensing Using Implanted Retroreflectors.

We demonstrate the feasibility of using optical coherence tomography (OCT) to image and detect 2.8 µm diameter microparticles (stationary and moving) on a highly-reflective gold surface both in clear media and under skin in vitro. The OCT intensity signal can clearly report the microparticle count, and the OCT response to the number of microparticles shows a good linearity. The detect ability of the intensity change (2.9% ± 0.5%) caused by an individual microparticle shows the high sensitivity of monitoring multiple particles using OCT. An optical sensing method based on this feasibility study is described for continuously measuring blood sugar levels in the subcutaneous tissue, and a molecular recognition unit is designed using competitive binding to modulate the number of bound microparticles as a function of glucose concentration. With further development, an ultra-small, implantable sensor might provide high specificity and sensitivity for long-term continuous monitoring of blood glucose concentration.

Classification of multiple sclerosis women with voiding dysfunction using machine learning: Is functional connectivity or structural connectivity a better predictor?

Introduction: Machine learning (ML) is an established technique that uses sets of training data to develop algorithms and perform data classification without using human intervention/supervision. This study aims to determine how functional and anatomical brain connectivity (FC and SC) data can be used to classify voiding dysfunction (VD) in female MS patients using ML. Methods: Twenty-seven ambulatory MS individuals with lower urinary tract dysfunction were recruited and divided into two groups (Group 1: voiders [V, n = 14]; Group 2: VD [n = 13]). All patients underwent concurrent functional MRI/urodynamics testing. Results: Best-performing ML algorithms, with highest area under the curve (AUC), were partial least squares (PLS, AUC = 0.86) using FC alone and random forest (RF) when using SC alone (AUC = 0.93) and combined (AUC = 0.96) as inputs. Our results show 10 predictors with the highest AUC values were associated with FC, indicating that although white matter was affected, new connections may have formed to preserve voiding initiation. Conclusions: MS patients with and without VD exhibit distinct brain connectivity patterns when performing a voiding task. Our results demonstrate FC (grey matter) is of higher importance than SC (white matter) for this classification. Knowledge of these centres may help us further phenotype patients to appropriate centrally focused treatments in the future.

Is the Brainstem Activation Different Between Healthy Young Male and Female Volunteers at Initiation of Voiding? A High Definition 7-Tesla Magnetic Resonance Imaging Study.

PURPOSE: Assessing brainstem function in humans through typical neuroimaging modalities has been challenging. Our objective was to evaluate brain and brainstem activation patterns during initiation of voiding in healthy males and females utilizing a 7 Tesla magnetic resonance imaging (MRI) scanner and a noninvasive brain-bladder functional MRI (fMRI) protocol. METHODS: Twenty healthy adult volunteers (10 males and 10 females) with no history of urinary symptoms were recruited. Each volunteer underwent a clinic uroflow and postvoid residual assessment and was asked to consume water prior to entering the scanner. Anatomical and diffusion tensor images were obtained first, followed by a blood oxygenation level dependent (BOLD) resting-state fMRI (rs-fMRI) during the empty bladder. Subjects indicated when they felt the urge to void, and a full bladder rs-fMRI was obtained. Once completed, the subjects began 5 voiding cycles, where the first 7.5 seconds of each voiding cycle was identified as "initiation of voiding." BOLD activation maps were generated, and regions of interests with a t-value greater than 2.1 were deemed statistically significant. RESULTS: We present 5 distinct regions within the periaqueductal gray (PAG) and pontine micturition center (PMC) with statistically significant activation associated with an initiation of voiding in both men and women, 3 within the PAG and 2 within the PMC. Several additional areas in the brain also demonstrated activation as well. When comparing males to females, there was an overall lower BOLD activation seen in females throughout all regions, with the exception of the caudate lobe. CONCLUSION: Our study effectively defines regions within the PAG and PMC involved in initiation of voiding in healthy volunteers. To our knowledge, this is the first study investigating differences between male and female brainstem activation utilizing an ultra-high definition 7T MRI.

Rigor and reproducibility in analysis of rodent behavior utilizing the forelimb reaching task following a cervical spinal cord injury.

Spinal cord injury (SCI) research with animals aims to understand the neurophysiological responses resultant of injury and to identify effective interventions that can translate into clinical treatments in the future. Consistent and reliable assessments to properly measure outcomes are essential to achieve this aim and avoid issues with reproducibility. The objective of this study was to establish a baseline for implementing the forelimb reaching task (FRT) assessment and analysis that increased reproducibility of our studies. For this study, we implemented a weekly FRT training program for six weeks. During this time the language of the scoring rubric for movement elements that comprise a reaching task was simplified and expanded. We calculated intra- and inter-rater variability among participants of the study both before and after training to determine the effect changes made had on rigor and reproducibility of this behavioral assessment in a cervical SCI rodent model. All animals (n = 19) utilized for FRT behavioral assessments received moderate contusion injuries using the Ohio State University device and were tested for a period of 5 weeks post-SCI. Videos used for scoring were edited and shared with all participants of this study to test FRT score variability and the effect simplification of the scoring rubric had on overall inter-rater reliability. From our results we determined training for a minimum of three weeks in FRT analysis is necessary for rigor and reproducibility of our behavioral studies, as well as the need for two raters to be assigned per animal to ensure accuracy of results.

Predictors for outcomes of noninvasive, individualized transcranial magnetic neuromodulation in multiple sclerosis women with neurogenic voiding dysfunction.

Purpose: Multiple sclerosis (MS) is a multifocal demyelinating disease that affects the central nervous system (CNS) and commonly leads to neurogenic lower urinary tract dysfunction (NLUTD). Proper storage and release of urine relies on synchronized activity of the LUT, which is meticulously regulated by supraspinal circuits, making it vulnerable to diseases such as MS. NLUTD, characterized by voiding dysfunction (VD), storage issues, or a combination of both is a common occurrence in MS. Unfortunately, there are limited treatment options for NLUTD, making the search for alternative treatments such as transcranial rotating permanent magnet stimulation (TRPMS) of utmost importance. To assess effectiveness of treatment we also need to understand underlying factors that may affect outcomes, which we addressed here. Methods: Ten MS subjects with VD and median age of 54.5 years received daily TRPMS sessions for two weeks. Five pre-determined regions of interest (ROIs) known to be involved in the micturition cycle were modulated (stimulated or inhibited) using TRPMS. Clinical data (non-instrumented uroflow and urodynamics parameters, PVR, bladder symptom questionnaires) and neuro-imaging data were collected at baseline and following TRPMS via 7-Tesla Siemens MAGNETOM Terra magnetic resonance imaging (MRI) scanner. Each participant underwent functional MRI (fMRI) concurrently with a repeated urodynamic study (UDS). Baseline data of each arm was evaluated to determine any indicators of successful response to treatment.

Selective Antagonism of A1 Adenosinergic Receptors Strengthens the Neuromodulation of the Sensorimotor Network During Epidural Spinal Stimulation.

Although epidural spinal stimulation (ESS) results in promising therapeutic effects in individuals with spinal cord injury (SCI), its potential to generate functional motor recovery varies between individuals and remains largely unclear. However, both preclinical and clinical studies indicate the capacity of electrical and pharmacological interventions to synergistically increase the engagement of spinal sensorimotor networks and regain motor function after SCI. This study explored whether selective pharmacological antagonism of the adenosine A1 receptor subtype synergizes with ESS, thereby increasing motor response. We hypothesized that selective pharmacological antagonism of A1 receptors during ESS would produce facilitatory effects in spinal sensorimotor networks detected as an increased amplitude of spinally-evoked motor potentials and sustained duration of ESS induced activity. Terminal experiments were performed in adult rats using trains of stereotyped pulses at 40 Hz delivered at L5 with the local administration to the cord of 8-cyclopentyl-1,3-dipropylxanthine (DPCPX). We demonstrated that ESS combined with the blockage of A1 receptors increased the magnitude of the endogenous modulation and postponed the decay of responses that occur during ESS alone. Although DPCPX significantly increased the yield of repetitive stimulation in intact spinal cords, the effects of A1 antagonism on motor evoked responses after an acute spinal transection was not detected. These studies support the future investigation of the optimal dosage, methods of delivery, and systemic effects of the synergistic application of A1 antagonists and spinal stimulation in the intact and injured spinal cord.

16-Channel Flexible System to Measure Electrophysiological Properties of Bioengineered Hearts.

As tissue engineering continues to mature, it is necessary to develop new technologies that bring insight into current paradigms and guide improvements for future experiments. To this end, we have developed a system to characterize our bioartificial heart model and compare them to functional native structures. In the present study, the hearts of adult Sprague-Dawley were decellularized resulting in a natural three-dimensional cardiac scaffold. Neonatal rat primary cardiac cells were then cultured within a complex 3D fibrin gel, forming a 3-dimensional cardiac construct, which was sutured to the acellular scaffold and suspended in media for 24-48 h. The resulting bioartificial hearts (BAHs) were then affixed with 16 electrodes, in different configurations to evaluate not only the electrocardiographic characteristics of the cultured tissues, but to also test the system's consistency. Histological evaluation showed cellularization and cardiac tissue formation. The BAHs and native hearts were then evaluated with our 16-channel flexible system to acquire the metrics associated with their respective electrophysiological properties. Time delays between the native signals were in the range of 0-95 ms. As well, color maps revealed a trend in impulse propagation throughout the native hearts. After evaluation of the normal rat QRS complex we found the average amplitude of the R-wave to be 5351.48 ± 44.92 µV and the average QRS duration was found to be 10.61 ± 0.18 ms. In contrast, BAHs exhibited more erratic and non-uniform activity that garnered no appreciable quantification. The data collected in this study proves our system's efficacy for EKG data procurement.

Electrical Activity of the Bladder Is Attenuated by Intravesical Inhibition of P2X2/3 Receptors During Micturition in Female Rats.

PURPOSE: To simultaneously monitor electrical discharges in various bladder regions and the external urethral sphincter (EUS) during voiding contractions, and to assess the functional role of myogenic modulation of the lower urinary tract (LUT) by ionotropic purinergic receptors containing the P2X3 subunit. METHODS: Female Sprague-Dawley rats were anesthetized with urethane, and implanted with a suprapubic catheter for open cystometry. Flexible microelectrodes were placed ventrally in the bladder dome, upper bladder, lower bladder, and bladder base, along with the middle section of the exposed EUS. Intravesical P2X3-containing receptors were blocked with AF-323, a specific P2X3-P2X2/3 receptor antagonist. A digital electrophysiology amplifier was used to record electrical and cystometric signals throughout the LUT. RESULTS: Electrical activity in the LUT started before effective voiding contractions. Bladder pressure and electrical waveforms showed consistent out-of-phase activity when compared with the recordings made at the EUS. This pattern was also observed during voiding contractions in the presence of AF-353, supporting the hypothesis that during bladder distension, activation of P2X3-containing receptors is required for voiding contractions. Furthermore, the inhibition of P2X3-containing receptors significantly decreased the amplitude of electrical signals in the urinary bladder, but not the base or EUS. CONCLUSIONS: Our results provide novel information about the regulation of the micturition process by P2X3-containing receptors located in the inner layers of the bladder.

32-Channel System to Measure the Electrophysiological Properties of Bioengineered Cardiac Muscle.

The purpose of this study was to develop, assess, and validate a custom 32-channel system to analyze the electrical properties of 3-D artificial heart muscle (3D-AHM). In this study, neonatal rat cardiac cells were cultured in a fibrin gel to drive the formation of 3D-AHM. Once the tissues were fully formed, the customized electrocardiogram (EKG) sensing system was used to obtain the different electrophysiological characteristics of the muscle constructs. Additionally, this system was used to evaluate the electrical properties of native rat hearts, for comparison to the fabricated tissues and native values found in the literature. Histological evaluation showed extensive cellularization and cardiac tissue formation. EKG data analysis yielded time delays between the signals ranging from 0 to 7 ms. Optical maps exhibited slight trends in impulse propagation throughout the fabricated tissue. Conduction velocities were calculated longitudinally at 277.81 cm/s, transversely at 300.79 cm/s, and diagonally at 285.68 cm/s for 3D-AHM. The QRS complex exhibited an R-wave amplitude of 438.42 ± 36.96 µV and an average duration of 317.5 ± 16.5 ms for the tissue constructs. The data collected in this study provide a clearer picture about the intrinsic properties of the 3D-AHM while proving our system's efficacy for EKG data procurement. To achieve a viable and permanent solution, the bioengineered heart muscle must physiologically resemble native heart tissue as well as mimic its electrical properties for proper contractile function. This study allows us to monitor such properties and assess the necessary changes that will improve construct development and function.

Development of a Cyclic Strain Bioreactor for Mechanical Enhancement and Assessment of Bioengineered Myocardial Constructs.

The purpose of this study was to develop enabling bioreactor technologies using a novel voice coil actuator system for investigating the effects of periodic strain on cardiac patches fabricated with rat cardiomyocytes. The bioengineered muscle constructs used in this study were formed by culturing rat neonatal primary cardiac cells on a fibrin gel. The physical design of the bioreactor was initially conceived using Solidworks to test clearances and perform structural strain analysis. Once the software design phase was completed the bioreactor was assembled using a combination of commercially available, custom machined, and 3-D printed parts. We utilized the bioreactor to evaluate the effect of a 4-h stretch protocol on the contractile properties of the tissue after which immunohistological assessment of the tissue was also performed. An increase in contractile force was observed after the strain protocol of 10% stretch at 1 Hz, with no significant increase observed in the control group. Additionally, an increase in cardiac myofibril alignment, connexin 43 expression, and collagen type I distribution were noted. In this study we demonstrated the effectiveness of a new bioreactor design to improve contractility of engineered cardiac muscle tissue.

Establishing the Framework for Fabrication of a Bioartificial Heart.

There is a chronic shortage of donor hearts. The ability to fabricate complete bioartificial hearts (BAHs) may be an alternative solution. The current study describes a method to support the fabrication and culture of BAHs. Rat hearts were isolated and subjected to a detergent based decellularization protocol to remove all cellular components, leaving behind an intact extracellular matrix. Primary cardiac cells were isolated from neonatal rat hearts, and direct cell transplantation was used to populate the acellular scaffolds. Bioartificial hearts were maintained in a custom fabrication gravity fed perfusion culture system to support media delivery. The functional performance of BAHs was assessed based on left ventricle pressure and on electrocardiogram. Furthermore, BAHs were sectioned and stained for the whole heart cardiac tissue distribution and for cardiac molecules, such as α-actinin, cardiac troponin I, collagen type I, connexin 43, von Willebrand factor, and ki67. Bioartificial hearts replicated a partial subset of properties of natural rat hearts. The current study provided a method for fabrication of a BAH and revealed challenges toward BAH fabrication with functional performance metrics of natural mammalian hearts.