Interstitial cystitis/bladder pain syndrome (IC/BPS) is characterized by persistent inflammation, urothelial barrier disruption, and extracellular matrix (ECM) degradation. However, the integrated mechanism linking inflammation, barrier dysfunction, and matrix remodeling remains unclear, limiting the development of effective regenerative therapies.

This study aims to elucidate the pathological features of IC/BPS through single-cell transcriptomic analysis and to develop a nanostructured bladder acellular matrix (nBAM)–based intravesical therapy that restores urothelial integrity via targeted mechanistic pathways.

Single-cell RNA sequencing (scRNA-seq) of human and cyclophosphamide (CYP)-induced IC bladder tissues was performed to characterize cellular heterogeneity and identify key pathological processes.

BAM and nanostructured BAM (nBAM) were prepared and compared using proteomic profiling. Cellular uptake and intravesical retention were evaluated by fluorescence tracing and in vivo imaging.

In vivo therapeutic efficacy was assessed in a CYP-induced rat IC model. Transcriptomic analysis (RNA-seq and GSEA) was conducted to identify signaling pathways involved in nBAM-mediated repair.

Mechanistic studies were performed by interfering with adhesion-related molecules to determine their role in pathway activation and therapeutic response.

Single-cell analysis revealed that IC is characterized by enhanced inflammatory signaling, impaired epithelial barrier function, and ECM degradation. Notably, PPARG expression was significantly downregulated in epithelial and stromal compartments in IC conditions.

Proteomic analysis demonstrated that nBAM retained key ECM components and exhibited enhanced bioactive molecule enrichment compared to BAM. Functional studies showed that nBAM had superior urothelial adhesion and intravesical retention capacity.

In vivo, nBAM significantly improved bladder function, reduced inflammation, and restored epithelial integrity compared to controls. Transcriptomic analysis revealed activation of the PPAR signaling pathway and suppression of inflammatory pathways, including NF-κB signaling.

Mechanistically, disruption of adhesion-related interactions attenuated nBAM-induced PPARγ activation and reduced its therapeutic effects, indicating that adhesion is a prerequisite for downstream signaling activation.

Figure legend:
Figure 1. Proteomic characterization and functional evaluation of nBAM
(A) Heatmap of differentially expressed proteins between BAM and nBAM; (B) KEGG pathway enrichment analysis of proteins enriched in nBAM; (C) Gene Ontology (GO) enrichment analysis of proteins enriched in nBAM; (D) Gene set enrichment analysis (GSEA) in nBAM; (E) Protein–protein interaction (PPI) network; (F) In vivo fluorescence imaging showing intravesical retention of nBAM in rat bladders; (G) Therapeutic effects of nBAM in a cyclophosphamide (CYP)-induced rat model, evaluated by bladder function and histological analysis; (H) Anti-inflammatory and barrier-protective effects of nBAM; (I) Transcriptomic analysis of bladder tissues following nBAM treatment.

nBAM promotes urothelial repair in IC/BPS through a two-step mechanism: enhanced adhesion to injured urothelium and subsequent activation of the PPARγ pathway, leading to inflammation suppression and barrier reconstruction.

These findings reveal a novel adhesion-dependent signaling activation model and support nBAM as a promising biomaterial for targeted regenerative therapy in IC/BPS.