Targeted mRNA restoration of ciliary function in DNAI1-related primary ciliary dyskinesia: ex vivo rescue in patient-derived nasal spheroids, A pilot study

RationalePrimary Ciliary Dyskinesia (PCD) is a genetic disorder characterized by impaired ciliary function, defective mucociliary clearance, and progressive lung disease. Pathogenic variants in the DNAI1 gene are a well-known cause of PCD. Currently, no approved therapies address the underlying genetic defect. RCT1100 is an inhaled mRNA therapy encoding DNAI1 currently under clinical development. This study evaluates the functional effects of RCT1100 using a fast three-dimensional explant spheroid (3DE-S) model consisting of apical-out undifferentiated nasal epithelial cells derived from patients with DNAI1 PCD. Methods3DE-S were generated from nasal brushings of five patients with confirmed biallelic DNAI1 variants. RCT1100 was administered from day 5 directly to culture wells three times weekly for two weeks. Spheroid motility was assessed throughout treatment by quantifying the proportion of moving spheroid rolling and their movement velocity. Following six doses, spheroids were harvested for high-speed video microscopy for assessment of ciliary beat frequency. ResultsEvaluable data were obtained from three of five patient samples; two samples were excluded due to contamination. After six doses of RCT1100, ciliary beat frequency increased from a baseline range of 2.8-3.5 Hz to 6.7-6.8 Hz post-harvesting. Mean spheroid movement velocity increased from 0.11 {micro}m/sec to 3.87 {micro}m/sec following dosing with 10 {micro}g/mL RCT1100, with more than 80% of spheroids exhibiting coordinated rolling motion pattern. ConclusionThe 3DE-S is a robust platform for evaluating targeted therapies. RCT1100 significantly restored ciliary function, supporting its therapeutic potential and highlighting the utility of spheroid-based systems for precision medicine approaches in DNAI1 PCD.