Minimal Invasive Cystometry and Intra-Abdominal Pressure Assessments in Rodents: A Novel Animal Study

METTL3-dependent m6A modification mediates bladder remodeling after partial bladder outlet obstruction through CCN2 activation

AIMS

N6-methyladenosine (m6A) modification is a critical posttranscriptional event in gene regulation. Thus, identifying methyltransferase, demethylase, or m6A binding protein-mediated m6A modifications in cancer or noncancer transcriptomes has become a promising novel strategy for disease therapy development. However, novel insights into m6A modification in partial bladder outlet obstruction (pBOO) and detailed information about the drivers of bladder remodeling remain to be elucidated. Here, we first characterized the m6A modification landscape in pBOO and investigated potential actionable pharmaceutical targets for future therapies.

METHODS

We generated an improved animal model of pBOO in SD rats with urethral meatus stricture induced by suturing. Urodynamic investigations and cystometry were carried out to evaluate the physiologic changes elicited by pBOO. Whole-transcriptome sequencing (RNA-seq) and m6A-modified RNA immunoprecipitation sequencing (MeRIP-seq) were subsequently performed to analyze the expression pattern associated with bladder remodeling in pBOO.

RESULTS

The cystometric evaluation of bladder function demonstrated obvious increases in pressure-related parameters in the pBOO group. Hematoxylin and eosin staining and Masson's trichrome staining validated the occurrence of bladder remodeling. A global elevation in m6A RNA methylation levels was observed in parallel to a increased expression of METTL3 in the pBOO group. High-throughput sequencing revealed the differences in expression patterns between the pBOO and sham-operated groups. Furthermore, potential m6A-modified genes, including CCN2, may serve as new pharmaceutical targets to reverse bladder remodeling.

CONCLUSIONS

Exploring the roles of m6A-modified genes identified as associated with bladder remodeling by integrating RNA-seq and MeRIP-seq data can offer new insights for developing promising treatments for pBOO patients.

Suture causing urethral meatus stricture: A novel animal model of partial bladder outlet obstruction

AIMS

Open surgery is the most commonly used methodological approach for generating a partial bladder outlet obstruction (pBOO) animal model. Surgical suturing closing a part of the urethral meatus induces comparable pathophysiological changes in bladder and renal functions, but the optimum degree of obstruction that closely mimics the clinical pathology of pBOO has not been elucidated. We investigated the optimum obstruction level by performing a comprehensive time-dependent analysis of the stability and reliability of this novel animal model.

METHODS

Six- to eight-week-old female BALB/c mice were divided into three groups according to the degree of urethral meatus stricture (UMS). Non-operated mice served as controls, and a pBOO model generated using the traditional method served as a positive control. A cystometric evaluation and long-term studies were performed to evaluate the validity and reliability of this novel animal model. An additional 35 mice were used to investigate the protein expression levels and histopathological features 24 h and 14 days postoperatively, respectively.

RESULTS

The characteristic cystometry features in the UMS group revealed increased changes in pressure-related parameters compared with the control. The 1/3 UMS model is an optional pBOO animal model because the cystometric evaluation and histopathological studies revealed a striking resemblance between the 1/3 UMS model and the model generated using the traditional open-surgery method.

CONCLUSIONS

The minimally invasive UMS model required less time and produced minimal alterations in pathophysiologically relevant processes compared with the traditional surgery model. Suturing to cause UMS produced effective and repeatable patterns in bladder function investigations in mice.