Inhibition of craniosynostosis and premature suture fusion in Twist1 mutant mice with RNA nanoparticle gene therapy

Craniosynostosis is a common birth defect affecting 1 of the 2200 live births causing severe skull and cognitive defects, due to premature cranial suture fusion. The current surgical treatments require invasive calvaria vault remodeling and cranial bone resection in the baby. We demonstrate that inhibition of miR-200a in PMIS–miR-200a mice results in coronal suture fusion (craniosynostosis). Therefore, we use overexpression of miR-200a to prevent suture fusion in Twist1 mutant mice, a well-known model for craniosynostosis. We developed a PEGylated-peptide nanoparticle system to deliver plasmid DNA expressing miR-200a directly to the sutures of postnatal day 4 (P4) Twist1 mutant mice before suture fusion. Injection of the miR-200a nanoparticles under the scalp before suture fusion at P7 to P10 inhibited suture fusion. Treatments increased Gli1- and Six2-positive suture stem cells and the thickness of the periosteum layer. The treated Twist1^+/− mice increased body weight and were alert and active. We demonstrate an effective noninvasive gene therapy treatment for craniosynostosis.