Bladder function recovery in rats with traumatic spinal cord injury after transplantation of neuronal-glial restricted precursors or bone marrow stromal cells

Stem Cell Therapy in Spinal Cord Injury-Induced Neurogenic Lower Urinary Tract Dysfunction

Spinal cord injury (SCI) is a devastating condition that enormously affects an individual's health and quality of life. Neurogenic lower urinary tract dysfunction (NLUTD) is one of the most important sequelae induced by SCI, causing complications including urinary tract infection, renal function deterioration, urinary incontinence, and voiding dysfunction. Current therapeutic methods for SCI-induced NLUTD mainly target on the urinary bladder, but the outcomes are still far from satisfactory. Stem cell therapy has gained increasing attention for years for its ability to rescue the injured spinal cord directly. Stem cell differentiation and their paracrine effects, including exosomes, are the proposed mechanisms to enhance the recovery from SCI. Several animal studies have demonstrated improvement in bladder function using mesenchymal stem cells (MSCs) and neural stem cells (NSCs). Human clinical trials also provide promising results in urodynamic parameters after MSC therapy. However, there is still uncertainty about the ideal treatment window and application protocol for stem cell therapy. Besides, data on the therapeutic effects regarding NSCs and stem cell-derived exosomes in SCI-related NLUTD are scarce. Therefore, there is a pressing need for further well-designed human clinical trials to translate the stem cell therapy into a formal therapeutic option for SCI-induced NLUTD.

Glial restricted precursor cells in central nervous system disorders: Current applications and future perspectives

The crosstalk between glial cells and neurons represents an exceptional feature for maintaining the normal function of the central nervous system (CNS). Increasing evidence has revealed the importance of glial progenitor cells in adult neurogenesis, reestablishment of cellular pools, neuroregeneration, and axonal (re)myelination. Several types of glial progenitors have been described, as well as their potentialities for recovering the CNS from certain traumas or pathologies. Among these precursors, glial-restricted precursor cells (GRPs) are considered the earliest glial progenitors and exhibit tripotency for both Type I/II astrocytes and oligodendrocytes. GRPs have been derived from embryos and embryonic stem cells in animal models and have maintained their capacity for self-renewal. Despite the relatively limited knowledge regarding the isolation, characterization, and function of these progenitors, GRPs are promising candidates for transplantation therapy and reestablishment/repair of CNS functions in neurodegenerative and neuropsychiatric disorders, as well as in traumatic injuries. Herein, we review the definition, isolation, characterization and potentialities of GRPs as cell-based therapies in different neurological conditions. We briefly discuss the implications of using GRPs in CNS regenerative medicine and their possible application in a clinical setting. MAIN POINTS: GRPs are progenitors present in the CNS with differentiation potential restricted to the glial lineage. These cells have been employed in the treatment of a myriad of neurodegenerative and traumatic pathologies, accompanied by promising results, herein reviewed.

Stem Cell Therapy for Neurogenic Bladder Dysfunction in Rodent Models: A Systematic Review

PURPOSE

Neurogenic bladder dysfunction (NGB) has an impact on the quality of life, which made it an important research subject in preclinical studies. The present review investigates the effect of stem cell (SC) therapy on bladder functional recovery after the onset of spinal cord injury (SCI), multiple sclerosis (MS), Parkinson disease (PD), and stroke in rodent models.

METHODS

All experiments evaluated the regenerative potential of SC on the management of NGB in rodent models up to June 2019, were included. From 1,189 relevant publications, 20 studies met our inclusion criteria of which 15 were conducted on SCI, 2 on PD, 2 on stroke, and 1 on MS in the rodent models. We conducted a meta-analysis on SCI experiments and for other neurological diseases, detailed urodynamic findings were reported.

RESULTS

The common SC sources used for therapeutical purposes were neural progenitor cells, bone marrow mesenchymal SCs, human amniotic fluid SCs, and human umbilical cord blood SCs. There was a significant improvement of micturition pressure in both contusion and transaction SCI models 4 and 8 weeks post-SC transplantation. Residual urine volume, micturition volume, and bladder capacity were improved 28 days after SC transplantation only in the transaction model of SCI. Nonvoiding contraction recovered only in 56 days post-cell transplantation in the contusion model.

CONCLUSION

Partial bladder recovery has been evident after SC therapy in SCI models. Due to limitations in the number of studies in other neurological diseases, additional studies are necessary to confirm the detailed mechanism for bladder recovery.

Effect of amniotic fluid stem cell transplantation on the recovery of bladder dysfunction in spinal cord-injured rats

The effects of human amniotic fluid stem cell (hAFSC) transplantation on bladder function and molecular changes in spinal cord-injured (SCI) rats were investigated. Four groups were studied: sham and SCI plus phosphate-buffered saline (SCI + PBS), human embryonic kidney 293 (HEK293) cells, and hAFSCs transplantation. In SCI + PBS rat bladders, cystometry showed increased peak voiding pressure, voiding volume, bladder capacity, residual volume, and number of non-voiding contractions, and the total elastin/collagen amount was increased but collagen concentration was decreased at days 7 and 28. Immunoreactivity and mRNA levels of IGF-1, TGF-β1, and β3-adrenoceptor were increased at days 7 and/or 28. M2 immunoreactivity and M3 mRNA levels of muscarinic receptor were increased at day 7. M2 immunoreactivity was increased, but M2/M3 mRNA and M3 immunoreactivity levels were decreased at day 28. Brain derived-neurotrophic factor mRNA was increased, but immunoreactivity was decreased at day 7. HEK293 cell transplantation caused no difference compared to SCI + PBS group. hAFSCs co-localized with neural cell markers and expressed BDNF, TGF-β1, GFAP, and IL-6. The present results showed that SCI bladders released IGF-1 and TGF-β1 to stimulate elastin and collagen for bladder wall remodelling, and hAFSC transplantation improved these changes, which involved the mechanisms of BDNF, muscarinic receptors, and β3-adrenoceptor expression.

Urodynamic Parameters in Spinal Cord Injury-Induced Neurogenic Bladder Rats after Stem Cell Transplantation: A Narrative Review

Neurogenic bladder (NGB) secondary to spinal cord injury (SCI) is accompanied with several complications such as urinary tract deterioration, urinary incontinence, and consequently lower quality of life (QoL), significant morbidities, and occasionally death. Current therapeutic methods have some side effects and there is no treatment for the upper urinary tract injuries. Stem cell therapy is a promising method for treating this condition. However, the best timing and the best route of its transplantation have not yet been determined. Animal models of SCI, especially in rats, are the most commonly used method for evaluating the efficacy of cell therapy in NGB improvement, and the most common assessment method is the urodynamic studies (UDS). However, there are variations in the range of UDS parameters among the published studies. The current review aimed to discuss the effect of stem cell transplantation on bladder dysfunction recovery based on urodynamic parameters after SCI in rats. For this purpose, the cell source, doses, the route of administration, and the complete UDS equipment and its parameters were summarized in SCI models in rats. In some urodynamic test results, to some extent, an improvement in the lower urinary system function was observed in each treatment group. However, this improvement was far from full functional recovery. The average cell dose was about 1 million cells in every injected site. In most studies, the stem cells (SCs) were transplanted 9 days after the injury using PE-50 and PE-60. Many researchers have recommended further experimental and clinical studies to confirm this treatment modality.

Establishment of Neurobehavioral Assessment System in Tree Shrew SCT Model

Tree shrews, possessing higher developed motor function than rats, were more suitable to study neurological behavior after spinal cord injury (SCI). Here, we established a feasible behavioral assessment method to detect the degree of ethology recovery in tree shrew subjected to spinal cord transection (SCT). Tree shrews were divided into normal group, sham group, and SCT group. The tree shrew in sham group was subjected to laminectomy without SCI, while the tree shrews in the SCT group were subjected to a complete SCT in thoracic 10 (T10). A novel neurobehavior assessment scale was established, in which, the behavior index including slow advancement, fast advancement, standing, shaking head, voluntary jump, lateral movement, and tail status, was determined, respectively. Meanwhile, magnetic resonance imaging (MRI) was applied to observe the structure of the spinal cord, and diffusion tensor imaging (DTI)-based white matter mapping was used to show the fibers of the spinal cord. As a result, a marked decrease in locomotor function and consciousness was seen in tree shrews with SCT, and the detection of MRI showed the collapsing of nerve fibers after SCT is completely cut and there is corresponding to the behavior change. Together, the present study provided a novel and feasible method that can be used to assess the neurobehavior in SCT model from tree shrews, which may be useful to the SCI translational study in future preclinic trial.

Ultrasound: A Valuable Translational Tool to Measure Postvoid Residual in Awake Rats?

BACKGROUND

Ultrasound is generally used to measure postvoid residual (PVR) in daily clinical practice for a basic assessment of voiding dysfunction. In animal research, however, PVR is measured mostly by expelling the urine with gentle squeezing of the bladder.

OBJECTIVE

To assess the translational value of measuring PVR by ultrasound in awake rats with the aim of obtaining directly comparable data sets in patients and rodent models.

DESIGN, SETTING, AND PARTICIPANTS

A prospective animal study was conducted in 10 rats with large, incomplete thoracic spinal cord injury resulting in severe bladder impairment. Lower urinary tract function was assessed by urodynamics with implanted bladder catheter and external urethral sphincter electrodes, allowing for repeated measurements over time. Immediately after the last micturition cycle in the urodynamic investigation, PVR was first assessed by ultrasound using a 7.5 MHz linear probe and then by manually expelling the urine via gentle pressure on the abdomen.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

PVR was measured by ultrasound and by manually expelling the urine. Paired t test was used to analyze the difference between the two measurements 1 and 2 wk after spinal cord injury.

RESULTS AND LIMITATIONS

PVR assessed by ultrasound was equal to and not statistically different from the volumes obtained by manual expulsion in intact rats, both before injury and during the first 2 wk after spinal cord injury (intact: 0.16 ± 0.07 vs 0.14 ± 0.09 ml, p =  0.08; week 1: 1.67 ± 0.53 vs 1.71 ± 0.55 ml, p =  0.67; week 2: 1.16 ± 0.35 vs 0.98 ± 0.43 ml, p =  0.11). The main limitation of ultrasound for measuring PVR is the restricted availability of ultrasound machines in animal research laboratories.

CONCLUSIONS

Ultrasound is a valuable translational tool to measure PVR in awake rats reflecting the situation in humans.

PATIENT SUMMARY

We measured postvoid residual by ultrasound in awake rats, analogous to clinical examination in humans. Ultrasonography provided similar values to the generally used manual bladder expulsion.

Improvement in Spinal Cord Injury-Induced Bladder Fibrosis Using Mesenchymal Stem Cell Transplantation into the Bladder Wall

Experiments on spinal cord injury (SCI) have largely focused on the transplantation of stem cells into injured spinal cords for motor recovery while neglecting to investigate bladder dysfunction. The present study was performed to investigate the effect of B10 human mesenchymal stem cells (hMSCs) directly transplanted into the bladder wall of SCI rats and to determine whether they are capable of inhibiting collagen deposition and improving cystometric parameters in SCI rats. Forty 6-week-old female Sprague–Dawley rats were divided into four groups (group 1: control, group 2: sham operated, group 3: SCI, group 4: SCI rats that received B10 cells). B10 cells were labeled with fluorescent magnetic nanoparticles (MNPs). Four weeks after the onset of SCI, MNP-labeled B10 cells were injected to the bladder wall. Serial magnetic resonance (MR) images were taken immediately after MNP-B10 injection and at 4 weeks posttransplantation. Voiding function was assessed at 4 weeks posttransplantation, and the bladder was harvested. Improvements in bladder fibrosis and bladder function were monitored by molecular MR imaging. Transplantation of B10 cells into the SCI rats markedly reduced their weights and collagen deposition. MR images showed a clear hypointense signal induced by the MNP-labeled B10 cells at 4 weeks posttransplantation. Transplanted B10 cells were found to differentiate into smooth muscle cells. The intercontraction interval decreased, and the maximal voiding pressure increased after SCI but recovered after B10 cell transplantation. Survival of B10 cells was found at 4 weeks posttransplantation using anti-human mitochondria antibody staining and MR imaging. The transplanted B10 cells inhibited bladder fibrosis and ameliorated bladder dysfunction in the rat SCI model. MSC-based cell transplantation may be a novel therapeutic strategy for bladder dysfunction in patients with SCI.

Bladder recovery by stem cell based cell therapy in the bladder dysfunction induced by spinal cord injury: systematic review and meta-analysis

BACKGROUND

Bladder dysfunction induced by spinal cord injury (SCI) can become problematic and severely impair the quality of life. Preclinical studies of spinal cord injury have largely focused on the recovery of limb function while neglecting to investigate bladder recovery.

OBJECTIVE

The present study was performed to investigate and review the effect of stem cell-based cell therapy on bladder recovery in SCI.

METHODS

We conducted a meta-analysis of urodynamic findings of experimental trials that included studies of stem cell-based cell therapy in SCI. Relevant studies were searched using MEDLINE, EMBASE and Cochrane Library (January 1990 - December 2012). Final inclusion was determined by a urodynamic study involving detailed numerical values. Urodynamic parameters for analysis included voiding pressure, residual urine, bladder capacity and non-voiding contraction (NVC). Meta-analysis of the data, including findings from urodynamic studies, was performed using the Mantel-Haenszel method.

RESULTS

A total of eight studies were included with a sample size of 224 subjects. The studies were divided into different subgroups by different models of SCI. After a stem cell-based cell therapy, voiding pressure (-6.35, p <0.00001, I2 = 77%), NVC (-3.58, p <0.00001, I2 = 82%), residual urine (-024, p = 0.004, I2 = 95%) showed overall significant improvement. Bladder capacity showed improvement after treatment only in the transection type (-0.23, p = 0.0002, I2 = 0%).

CONCLUSION

After stem cell-based cell therapy in SCI, partial bladder recovery including improvement of voiding pressure, NVC, and residual urine was demonstrated. Additional studies are needed to confirm the detailed mechanism and to obtain an ideal treatment strategy for bladder recovery.

Virus integration and genome influence in approaches to stem cell based therapy for andro-urology

Despite the potential of stem cells in cell-based therapy, major limitations such as cell retention, ingrowth, and trans-differentiation after implantation remain. One technique for genetic modification of cells for tissue repair is the introduction of specific genes using molecular biology techniques, such as virus integration, to provide a gene that adds new functions to enhance cellular function, and to secrete trophic factors for recruiting resident cells to participate in tissue repair. Stem cells can be labeled to track cell survival, migration, and lineage. Increasing evidence demonstrates that cell therapy and gene therapy in combination remarkably improve differentiation of implanted mesenchymal stromal cells (MSCs), revascularization, and innervation in genitourinary tissues, especially to treat urinary incontinence, erectile dysfunction, lower urinary tract reconstruction, and renal failure. This review discusses the benefits, safety, side effects, and alternatives for using genetically modified MSCs in tissue regeneration in andro-urology.

Stem cell therapy in bladder dysfunction: where are we? And where do we have to go?

To date, stem cell therapy for the bladder has been conducted mainly on an experimental basis in the areas of bladder dysfunction. The therapeutic efficacy of stem cells was originally thought to be derived from their ability to differentiate into various cell types. Studies about stem cell therapy for bladder dysfunction have been limited to an experimental basis and have been less focused than bladder regeneration. Bladder dysfunction was listed in MESH as "urinary bladder neck obstruction", "urinary bladder, overactive", and "urinary bladder, neurogenic". Using those keywords, several articles were searched and studied. The bladder dysfunction model includes bladder outlet obstruction, cryoinjured, diabetes, ischemia, and spinal cord injury. Adipose derived stem cells (ADSCs), bone marrow stem cells (BMSCs), and skeletal muscle derived stem cells (SkMSCs) are used for transplantation to treat bladder dysfunction. The main mechanisms of stem cells to reconstitute or restore bladder dysfunction are migration, differentiation, and paracrine effects. The aim of this study is to review the stem cell therapy for bladder dysfunction and to provide the status of stem cell therapy for bladder dysfunction.

Intravenously transplanted bone marrow stromal cells promote recovery of lower urinary tract function in rats with complete spinal cord injury

OBJECTIVES

There is increasing evidence that intravenously injected neural progenitor cells promote recovery of bladder function in rodents, following contusive spinal cord injury through migrating into the injured spinal cord tissue and differentiating into central nervous system cells. The present study was aimed to clarify whether intravenously transplanted bone marrow stromal cells (BMSCs) could improve lower urinary tract (LUT) function in rats with spinal cord transection (SCT).

METHODS

A total of 22 rats underwent experimentation in three groups, including group 1-sham operation, group 2 (BMSC)-SCT plus BrdU (5-bromo-2'-deoxyuridine) labeled BMSCs transplantation at day 9 after SCT, group 3-SCT control. All rats were investigated urodynamically on day 28 after transplantation.

RESULTS

BMSCs identified by BrdU immunohistochemistry survived in the injured spinal cord and lumbar level 3-4 (L(3-4)). Voiding pressure, episodes of non-voiding contractions and residual urine volumes were significantly decreased in BMSC rats, compared with the controls. Bladder capacity was similar in both groups. In four out of eight BMSC rats and one out of seven controls, the tonic and bursting external urethral sphincter electromyographic activity were detected during cystometry. Silent periods during bursting were shorter and activity periods were longer in BMSC rats compared with sham rats.

CONCLUSION

Intravenously transplanted BMSCs survived in the L(3-4) and had beneficial effects on the recovery of LUT function in the rats after SCT.

Early graft of neural precursors in spinal cord compression reduces glial cyst and improves function

OBJECTIVE

Spinal cord injury (SCI) often results in irreversible and permanent neurological deficits below the injury site and is considered a pathological state of functional damage to local neurons and axon fibers. There are several experimental treatments to minimize tissue damage, and recently cell transplantation has emerged as a promising approach in spinal cord repair. The authors undertook this study to evaluate grafting of neural tube precursors as a possible therapeutic strategy in a model of spinal cord compression in the mouse.

METHODS

Compression SCI was induced at the T-13 level in adult male mice. Immediately after injury, neural precursor cells (NPs) were transplanted into the SCI lesion cavity in 18 mice; the remaining 19 mice received saline injections into the lesion cavity and were used as controls. Spinal cords were examined 12, 19, and 26 days postinjury to investigate the survival of the NPs and their effects on the cellular environment, glial scar and glial cyst formation, astrogliosis, and microglial activation.

RESULTS

Grafted NPs survived well and integrated into the host spinal cord tissue. Some NPs had differentiated into cells expressing glial and neuronal markers at all 3 end points. Analysis of glial cyst volume showed a lesion volume reduction of 63.2% in the NP-treated mice compared with volume in the injured but untreated mice. There appeared to be no difference in astroglial and microglial activation between untreated mice and treated ones. Sensory and motor tests demonstrated that transplantation of NPs promoted improvement in injured and treated animals compared with controls.

CONCLUSIONS

These results support the therapeutic potential of NPs, demonstrating that they can survive for a long time, differentiate, integrate into the injured spinal cord, and promote functional recovery after SCI.

Glial restricted precursor cell transplant with cyclic adenosine monophosphate improved some autonomic functions but resulted in a reduced graft size after spinal cord contusion injury in rats

Transplantation of glial restricted precursor (GRP) cells has been shown to reduce glial scarring after spinal cord injury (SCI) and, in combination with neuronal restricted precursor (NRP) cells or enhanced expression of neurotrophins, to improve recovery of function after SCI. We hypothesized that combining GRP transplants with rolipram and cAMP would improve functional recovery, similar to that seen after combining Schwann cell transplants with increasing cAMP. A short term study, (1) uninjured control, (2) SCI+vehicle, and (3) SCI+cAMP, showed that spinal cord [cAMP] was increased 14days after SCI. We used 51 male rats subjected to a thoracic SCI for a 12-week survival study: (1) SCI+vehicle, (2) SCI+GRP, (3) SCI+cAMP, (4) SCI+GRP+cAMP, and (5) uninjured endpoint age-matched control (AM). Rolipram was administered for 2weeks after SCI. At 9days after SCI, GRP transplantation and injection of dibutyryl-cAMP into the spinal cord were performed. GRP cells survived, differentiated, and formed extensive transplants that were well integrated with host tissue. Presence of GRP cells increased the amount of tissue in the lesion; however, cAMP reduced the graft size. White matter sparing at the lesion epicenter was not affected. Serotonergic input to the lumbosacral spinal cord was not affected by treatment, but the amount of serotonin immediately caudal to the lesion was reduced in the cAMP groups. Using telemetric monitoring of corpus spongiosum penis pressure we show that the cAMP groups regained the same number of micturitions per 24hours when compared to the AM group, however, the frequency of peak pressures was increased in these groups compared to the AM group. In contrast, the GRP groups had similar frequency of peak pressures compared to baseline and the AM group. Animals that received GRP cells regained the same number of erectile events per 24hours compared to baseline and the AM group. Since cAMP reduced the GRP transplant graft, and some modest positive effects were seen that could be attributable to both GRP or cAMP, future research is required to determine how cAMP affects survival, proliferation, and/or function of progenitor cells and how this is related to function. cAMP may not always be a desirable addition to a progenitor cell transplantation strategy after SCI.

The effect of mesenchymal stem cell transplantation on the recovery of bladder and hindlimb function after spinal cord contusion in rats

Background

Mesenchymal stem cells are widely used for transplantation into the injured spinal cord in vivo model and for safety, many human clinical trials are continuing to promote improvements of motor and sensory functions after spinal cord injury. Yet the exact mechanism for these improvements remains undefined. Neurogenic bladder following spinal cord injury is the main problem decreasing the quality of life for patients with spinal cord injury, but there are no clear data using stem cell transplantation for the improvement of neurogenic bladder for in vivo studies and the clinical setting.

The purpose of this study was to delineate the effect of human mesenchymal stem cell (hMSCs) transplantation on the restoration of neurogenic bladder and impaired hindlimb function after spinal cord contusion of rats and the relationship between neurotrophic factors such as brain derived neurotrophic factor (BDNF) and neurotrophin-3 (NT-3) and bladder and hindlimb functions.

Results

Modified moderate contusion injury were performed on the thoracic spinal cord of Sprague-Dawley rats using MASCIS impactor and hMSCs, human fibroblasts or phosphate-buffered saline were transplanted into injured spinal cord 9 days after injury for hMSC and two control groups respectively. Ladder test showed more rapid restoration of hindlimb function in hMSC group than in control group, but Basso, Beattie, and Bresnahan score and coupling score were not different significantly among hMSC and two control groups. Neurogenic bladder was not improved in either group. ED1 positive macrophages were significantly reduced in hMSC group than in two control groups, but ELISA and RT-PCR studies revealed BDNF and NT-3 levels in spinal cord and bladder were not different among hMSC and two control groups regardless the experimental duration.

Conclusion

hMSC transplantation was effective in reducing inflammatory reaction after spinal cord contusion of rats but not sufficient to recover locomotor and bladder dysfunction. BDNF and NT-3 levels in the spinal cord and bladder were not increased 28 and 56 days after hMSC transplantation.

Olfactory mucosal transplantation after spinal cord injury improves voiding efficiency by suppressing detrusor-sphincter dyssynergia in rats

PURPOSE

Several recent studies showed that olfactory mucosal transplantation after spinal cord injury promotes extensive regeneration of the injured spinal cord. We examined the efficacy of olfactory mucosal transplantation for bladder dysfunction after spinal cord injury in rats.

MATERIALS AND METHODS

In adult female rats the Th9-10 spinal cord was completely transected, followed by olfactory mucosal transplantation or gelatin sponge filling as the control. Each group was examined by cystometrogram and external urethral sphincter electromyogram. Calcitonin gene-related peptide and growth associated protein 43 double positive expression in the L6/S1 dorsal horn was evaluated by immunohistochemistry. Transplant sites were examined by immunohistochemistry with antibodies against neurofilament M and neuronal class III beta-tubulin.

RESULTS

On cystometrogram voiding efficiency was significantly higher in the transplantation group than in controls. On external urethral sphincter electromyogram with simultaneous cystometrogram the transplantation group showed a larger ratio of interburst silent periods to burst activity duration and a greater number of high frequency oscillations. In the transplantation group calcitonin gene-related peptide and growth associated protein 43 double positive expression in the L6/S1 dorsal horn was less dense than in controls. The transplantation group showed strong neurofilament M and neuronal class III beta-tubulin expression at the transplant site.

CONCLUSIONS

Olfactory mucosal transplantation after spinal cord injury weakened external urethral sphincter excessive bursting and increased the urethral opening to improve voiding efficiency. Olfactory mucosal transplantation may modify emergence of the spinal micturition reflex after spinal cord injury. Transplantation resulted in new axons growing at the transplant site, implying the possible existence of interneuron bridging across the injured spinal cord.