Assessment of Migration of the Urethral Bulking Agent Zhoabex G® from the Urethral Injection Site to the Distant Organs in a Rabbit Model

Hyaluronic acid (HA)-based urethral bulking agents are promising for the treatment of stress urinary incontinence (SUI), but migration risks to distant organs remain a concern. This study evaluated the migration and cytotoxicity of Zhoabex G^®, an HA-based bulking agent, in a female rabbit model. Twenty-seven female New Zealand white rabbits were randomized into control (no injection), sham (saline), and experimental (Zhoabex G^®) groups (<i>n</i> = 9 each). After 5 months, tissues from the kidney, lung, liver, and spleen were analyzed using quantitative RT-PCR for hyaluronan synthase (HAS1, HAS2, HAS3) and hyaluronidase (HYAL2) gene expression, and ELISA for HA concentrations. No significant differences in gene expression were observed across groups (<i>p</i> ≥ 0.05, range: 0.166-0.997), with experimental fold change values near sham baselines (e.g., kidney HAS2: 0.987 ± 0.071, <i>p</i> = 0.422). Similarly, HA concentrations showed no group differences (<i>p</i> = 0.577; e.g., kidney: 119.2-121.8 ng/mL), reflecting organ-specific basal levels. These findings indicate that Zhoabex G^® remains localized at the urethral injection site, with no evidence of migration or cytotoxicity in distant organs. The biodegradable and non-particulate nature of Zhoabex G^® further supports its safety for SUI treatment, warranting further clinical investigation.