Herpes simplex virus vector-mediated gene transfer of kynurenine aminotransferase improves detrusor overactivity in spinal cord-injured rats

Botulinum toxin A improves neurogenic bladder fibrosis by suppressing transforming growth factor β1 expression in rats

Background

Intradetrusor botulinum toxin A injection is recommended for the treatment of refractory detrusor overactivity (DO) in patients with neurogenic bladder, however, whether it could inhibit neurogenic bladder fibrosis is uncertain. This study aimed to investigate the effect of botulinum toxin A on neurogenic bladder fibrosis and the underlying mechanism.

Methods

Forty eight Female Wistar rats were evenly randomized into 4 groups: Sham, T10 transection, Early and Late groups. The last three groups were subjected to T10 spinal cord transection, while the Sham group was treated with sham surgery. 0.9% saline was injected into the detrusor in the Sham and T10 transection groups simultaneously with the surgery, while 2 U/rat botulinum toxin A was injected into the detrusor simultaneously with the surgery in the Early group and 4 weeks following the surgery in the Late group. Body/bladder weight, cystometric parameters, bladder Hematoxylin-eosin staining were used to evaluate the bladder fibrosis. Western blot and quantitative Real-time PCR were used to evaluate the expression of bladder transforming growth factor β1.

Results

Compared with the T10 transection group, the bladder/body weight was decreased significantly in the Early and Late groups (P<0.05), along with the significant inhibition of non-voiding contraction (NVC) frequency and amplitude (P<0.05), and the significant increase of bladder volume (P<0.05). The detrusor connective tissue percentage (P<0.05) and the expression of transforming growth factor β1 (P<0.05) also decreased significantly in the Early and Late groups. Those changes were more obviously in the Early group than in the Late group.

Conclusions

Intradetrusor botulinum toxin A injection reduced bladder fibrosis in rats with spinal cord injury (SCI), which was more obviously in the Early group than in the Late group. The mechanisms might be mediated by suppression of transforming growth factor β1 (TGF-β1) expression.

Inhibiting the kynurenine pathway in spinal cord injury: Multiple therapeutic potentials?

Chronic induction of the kynurenine pathway (KP) contributes to neuroinflammation by producing the excitotoxin quinolinic acid (QUIN). This has led to significant interest in the development of inhibitors of this pathway, particularly in the context of neurodegenerative disease. However, acute spinal cord injury (SCI) also results in deleterious increases in QUIN, as secondary inflammatory processes mediated largely by infiltrating macrophages, become predominant. QUIN mediates significant neurotoxicity primarily by excitotoxic stimulation of the N-methyl-D-aspartate receptor, but other mechanisms of QUIN toxicity are known. More recent focus has assessed the contribution that neuroinflammation and modulations in the KP make in mood and psychiatric disorders with recent studies linking inflammation and modulations in the KP, to impaired cognitive performance and depressed mood in SCI patients. We hypothesize that these findings suggest that in SCI, inhibition of QUIN production and other metabolites, may have multiple therapeutic modalities and further studies investigating this are warranted. However, for central nervous system-based conditions, achieving good blood-brain-barrier permeability continues to be a limitation of current KP inhibitors.

Increasing bladder capacity by foot stimulation in rats with spinal cord injuries

Background

This study was to explore the possibility that foot stimulation increased bladder capacity(BC) in rats with neurogenic bladder secondary to T10 spinal cord injuries.

Methods

In 20 awake rats (stimulation group) with T10 spinal cord injuries, 5 repeat cystometrograms (CMGs) were recorded. The 1st and 2nd CMGs were performed without stimulation. The 3rd, 4th, and 5th CMGs were done separately with 1 T, 2 T, and 4 T stimulation, respectively, through a pair of pad electrodes on the skin of the hind foot. In the control group of 20 rats, 5 repeat CMGs were recorded without foot stimulation. The threshold (T) was the minimal stimulation intensity to induce an observable toe twitch.

Results

In the stimulation group, foot stimulation with 2 T significantly increased the BC an additional 68.9% ± 20.82% (p < 0.05). Foot stimulation with 4 T increased the BC an additional 120.9% ± 24.82% (p < 0.05). Compared with the control group, BC in the 1st, 2nd, and 3rd (1 T) CMG had no significant difference in the stimulation group, but the 4th (2 T) and 5th (4 T) CMGs were significantly increased (p < 0.05).

Conclusions

Electrical stimulation of the foot was effective in inhibiting reflex bladder activity and increasing bladder capacity in spinal cord injury rats.

Improvement in detrusor-sphincter dyssynergia by bladder-wall injection of replication-defective herpes simplex virus vector-mediated gene delivery of kynurenine aminotransferase II in spinal cord injury rats

STUDY DESIGN

An experimental study.

OBJECTIVES

To investigate the effect of replication-defective herpes simplex virus (HSV) vectors encoding the kynurenine aminotransferase II (HSVrd-KATII) gene on detrusor-sphincter dyssynergia (DSD) in spinal cord injury (SCI) rats.

SETTING

Beijing, China.

METHODS

Sprague-Dawley rats (240-265 g) were spinalized with complete transaction at the T10 level of the spinal cord. The rats were randomly divided into the following three groups: sham group (n=12, with normal saline); HSVrd group (n=12, with HSVrd) and HSVrd-KATII group (n=12, with HSVrd-KATII). One week after spinalization normal saline, HSVrd or HSVrd-KATII was injected into the bladder walls of the three groups, respectively. Three weeks after virus injection, the urethral pressure profile (UPP) and continuous cystometry were performed under awake conditions and gene expression was evaluated in all of the SCI rats.

RESULTS

In the HSVrd-KATII group, the maximum urethral closure pressure (Pclo.max), maximum voiding pressure (MVP), and the number and amplitude of non-voiding contraction (NVCs) were significantly decreased (34.7-39.1%, 46.7-56.2% and 31.5-32.5%, respectively), along with an increase in voiding efficiency (49.1-52.1%) compared with the sham and HSVrd groups. In addition, the levels of KATII protein and mRNA were significantly increased in the L6-S1 dorsal root ganglia (DRG) and L6-S1 spinal cord segments in the HSVrd-KATII group compared with the HSVrd group.

CONCLUSIONS

HSVrd vector encoding the KATII gene effectively improved DSD and detrusor overactivity by bladder-wall injection, perhaps by blocking N-methyl-d-aspartate receptors in the L6-S1 dorsal root ganglion and L6-S1 spinal cord.

Effect of urethral wall injection of replication-defective herpes simplex virus-mediated gene transfer of kynurenine aminotransferase on urethral pressure in spinal cord-injured rats

AIMS

We determined whether or not replication-defective herpes simplex virus vector-mediated kynurenine aminotransferase II (HSVrd-KAT II) suppressed the tonic activity of the urethral sphincter in spinal cord-injured (SCI) rats.

METHODS

Thirty-six adult female Sprague-Dawley rats were used to produce a spinal cord injury model. One week after spinalization, HSVrd-KAT II was injected into the urethral wall of rats and another two groups of SCI rats were treated with saline and HSVrd as controls. Three weeks after viral injection, the urethral pressure profile (UPP), continuous cystometry, and gene expression in the L6-S1 spinal cords were evaluated in all three groups.

RESULTS

In the HSVrd-KAT II group, the maximum urethral closure pressure (Pclo.max) and maximum voiding pressure were significantly decreased (23.6-24.9% and 31.6-30.9%, respectively), in addition to an increase in voiding efficiency(48.8-76%), compared with the sham and HSVrd groups. The KAT II protein and mRNA levels were significantly increased in HSV-KAT II group compared with the HSVrd group.

CONCLUSION

KAT II gene therapy effectively reduced the urethral pressure, improving detrusor-sphincter dyssynergia (DSD), and detrusor overactivity (DO), probably by blocking the N-methyl-D-aspartate receptor (NMDAr) in the L6-S1 spinal cord. Neurourol. Urodynam. 36:1046-1051, 2017. © 2016 Wiley Periodicals, Inc.

Evaluation and Management of Neurogenic Bladder: What Is New in China?

Neurogenic bladder (NB) or neurogenic lower urinary tract dysfunction (NLUTD), a dysfunction of the urinary bladder and urethra due to disease of the central nervous system or peripheral nerves, is a major global medical and social problem. Numerous nervous system abnormalities, such as: stroke, Alzheimer's and Parkinson's diseases, traumatic spinal cord injury, spinal cord tumors, congenital spina bifida, and diabetes, can cause NB/NLUTD. There are two major types of bladder control problems associated with NB/NLUTD: the bladder becomes either overactive or underactive depending on the nature, level, and extent of nerve damage. This review specifically focuses on the diagnosis and management of NB/NLUTD in China as well as on recent efforts to treat this disease.