Exploring biomechanical methods to study the human vaginal wall

Release Kinetics of Metronidazole from 3D Printed Silicone Scaffolds for Sustained Application to the Female Reproductive Tract

Sustained vaginal administration of antibiotics or probiotics has been proposed to improve treatment efficacy for bacterial vaginosis. 3D printing has shown promise for development of systems for local agent delivery. In contrast to oral ingestion, agent release kinetics can be fine-tuned by the 3D printing of specialized scaffold designs tailored for particular treatments while enhancing dosage effectiveness via localized sustained release. It has been challenging to establish scaffold properties as a function of fabrication parameters to obtain sustained release. In particular, the relationships between scaffold curing conditions, compressive strength, and drug release kinetics remain poorly understood. This study evaluates 3D printed scaffold formulation and feasibility to sustain the release of metronidazole, a commonly used antibiotic for BV. Cylindrical silicone scaffolds were printed and cured using three different conditions relevant to potential future incorporation of temperature-sensitive labile biologics. Compressive strength and drug release were monitored for 14d in simulated vaginal fluid to assess long-term effects of fabrication conditions on mechanical integrity and release kinetics. Scaffolds were mechanically evaluated to determine compressive and tensile strength, and elastic modulus. Release profiles were fitted to previous kinetic models to differentiate potential release mechanisms. The Higuchi, Korsmeyer-Peppas, and Peppas-Sahlin models best described the release, indicating similarity to release from insoluble or polymeric matrices. This study shows the feasibility of 3D printed silicone scaffolds to provide sustained metronidazole release over 14d, with compressive strength and drug release kinetics tuned by the fabrication parameters.

An operator-independent artificial finger can differentiate anterior vaginal wall indentation parameters between control and prolapse patients

In this study, the reproducibility and validity of an automated artificial finger for evaluating properties of vaginal wall tissue was assessed. The effect of angle and rate of indentation on displacing the anterior vaginal wall (AVW) was studied in control and prolapse patients. Following IRB approval, an automated artificial finger equipped with a calibrated piezoresistive sensor at its tip was used to induce 3-second AVW deformation sequences (10°, 15°, and 20° indentation). Measurements were taken in patients in supine position, either awake in clinic or under anesthesia in the operating room (OR). The real time voltage output of a sensor (linearly proportional to the reaction force) was recorded for each motion profile to calculate key parameters: baseline voltages, amplitude changes over indentation intervals, and slopes of indentation curves. 23 women (9 controls and 14 prolapse) were studied, 6 in clinic and 17 in OR. No differences in mean reproducibility was noted across groups. There was a significant difference in sensor output based on selected motion profile parameters between different degrees of indentation for all women (p < 0.001) and in baseline voltage between age-matched and non-age-matched controls (p < 0.02). From these findings, we can conclude that indentation reaction properties of prolapsed and non-prolapsed AVW can be objectively measured using an operator-independent artificial finger with significant differences between patient groups.