Interstitial cystitis/bladder pain syndrome (IC/BPS) is a chronic bladder condition with limited treatment options. Intravesical platelet-rich plasma (PRP) injections may help regenerate the urothelium and reduce inflammation. This study explores the correlation between the treatment outcomes with subjective and objective parameters in IC/BPS patients.

A total of 98 patients with non-Hunner lesion IC/BPS (BPS) were enrolled from 2016 to December 2023. This retrospective study includes BPS patients who underwent monthly injections of 10 mL intravesical PRP injections for four months, followed by a Global Response Assessment (GRA) after three months. All patients had been previously confirmed to have IC/BPS according to the NIDDK criteria. Briefly, they had cardinal symptoms of frequency nocturia and bladder pain not relieved by conventional treatment for more than six months, and no lower urinary tract pathology could be identified. Further, all patients had glomerulations of bladder wall after cystoscopic hydrodistention findings of glomerulations, petechia, or mucosal fissures. All patients were informed of the possible complications associated with intravesical PRP injection, such as hematuria, micturition pain, transient urinary retention, or urinary tract infections (UTIs). The evaluation of treatment outcomes included clinical symptoms score, pain severity, voiding diary, uroflowmetry parameters, GRA score, and baseline urine biomarkers were measured to identify factors that contribute to satisfactory treatment outcomes.

In this retrospective study, 98 patients (16 men, 82 women) with a mean age of 54.25 ± 12.33-year-old, a mean IC duration of 12.64 ± 9.99 years, and a mean MBC of 684.39 ± 174.52 mL. First of all, in overall VUDS parameters, the mean of FSF is 128.09 ± 53.37 mL, the mean of FS is 203.4 ± 84.46 mL, the mean of Pdet is 22.29±14.78 cmH2O, and the mean of CBC is 260.13 ± 114.15 mL. In the subjective parameters, the mean of ICSI is 10.82 ± 4.43 points, ICPI is 10.6 ± 3.38 points, and bladder pain severity of the mean of NRS is 3.78 ± 3.08 points. On the 3-day voiding diary, the mean wake-up urination frequency is 13.88 ± 8.9 times, nocturia at night is 3.09 ± 1.87 times, and the mean of FBC is 267.63 ± 129.25 mL. In addition, in the uroflowmetry study, the mean of Qmax is 10.88 ± 6.5 mL/sec, the mean of voided volume is 205.16 ± 110.74 mL, and PVR is 46.36 ± 107.11 mL. Meanwhile, patients all have more than moderate anxiety severity in BAI (mean of BAI: 22.37 ± 12.27 points) (Table 1). In addition, when we compared the patients' urine biomarkers with inflammatory cytokines, and oxidative stress proteins, including IL-8, IP-10, MCP-1, NGF, BDNF, exotoxin, IL-2, IL-6, MCP-1β, rantes, TNF-α, PGE2, and 8-OHDG, 8-isoprostane, and TAC (Table 2). The results show there are significant differences between higher inflammatory cytokines levels of MCP1, exotoxin, TNF-α, PGE2, oxidative stress protein of 8-OHDG, and 8-isoprostane and lower NGF, IL-2, and MIP1β urine biomarker levels in BPS patients compared to the control group. However, there is no significant difference between different treatment outcomes groups. Furthermore, in different treatment outcome groups, as time goes by PRP injection treatment whatever self-reported treatment outcomes, MBC, and glomerulation grade under anesthesia would improve after treatments. In accordance with the significant improvement in patients' self-reported ICSI and ICPI, there is a significant improvement in MBC and a tendency to get better in glomerulation grade after PRP injection.

The study has demonstrated that repeat autologous intravesical PRP injection treatments can safely and effectively decrease self-feeling IC symptoms and problem severity, bladder pain severity, and anxiety severity, a frequency in wake-up and nocturia in sleep-time would also be reduced, and even on FBC would have significant increased, and further to improve the maximum flow rate and voided volume without increasing PVR. 78.6% of IC/BPS patients have slightly improved. Even over half (55.1%) of patients would achieve a significantly satisfactory outcome after four times intravesical PRP injections, and no specific phenotypes of BPS patients are likely to experience unsatisfactory outcomes. In addition, not only improvement in self-feeling parameters but also MBC has been significantly improved under anesthesia after times of intravesical PRP injections.

Repeated intravesical PRP injections were safe and effective for reducing symptoms, pain release, and improving bladder capacity in a majority of IC/BPS patients, regardless of phenotype. The results support further research on PRP as a promising new therapy for this challenging condition.