Remote control of mechano-sensory function of primary cilia by Fe2O3 nanoparticles in ciliopathic animal models

R. Pala, S.M. Nauli
Chapman University and University of California Irvine,
United States

Keywords: mechano-sensory, nanoparticles, magnetism, live cell imaging, Pkd2 mice


Primary cilia are cellular organelles with chemo- and mechano-sensory roles. Biochemical and molecular defects in primary cilia are associated with a wide range of diseases, termed ciliopathies, with phenotypes ranging from kidney diseases, liver disorders, obesity and cardiovascular diseases. In the present studies, we designed a cilia-targeted delivery system to deliver fenoldopam specifically to the primary cilia. Nanomaterials have been used for a targeted drug delivery and a sustained drug release. Nanomaterials can therefore decrease the overall drug toxicity by delivering a smaller drug dosage. Hence, we devised the iron oxide nanoparticle (Fe2O3-NP)-based technology for ciliotherapy. Dynamic light scattering measurements showed that upon surface functionalization, the size distributions were increased from 102±3.8 to 126±4.6 nm. When the surface charge of the particles was analyzed, the charge repulsion increased after every functionalization step from +12.9±2.8 to -27.9±3.4. The successful formation of bare NPs and their surface functionalization were also examined by collecting X-ray diffraction and X-ray photoelectron spectra. Live imaging confirmed that the Fe2O3-NPs specifically targeted primary cilia in cultured cells in vitro and vascular endothelia in vivo. Importantly, the Fe2O3-NPs enabled the remote control of the movement and function of a cilium with an external magnetic field, making the non-motile cilium exhibit passive movement. We investigated the effect of the Fe2O3-NPs in targeting primary cilia by injecting them intravenously in the tail of an endothelial-specific Pkd2 mouse model for 8 weeks (Tie2Cre•Pkd2flox/flox). The in vivo cilia specificity of the Fe2O3-NPs was examined in isolated femoral arteries. The localization of the Fe2O3-NPs in the vascular endothelium was confirmed at 24 and 72 hours after the injections. Cilia length was significantly increased in mice treated with the Fe2O3-NPs but not in mice that received a 30 min infusion of fenoldopam. The ciliopathic hearts displayed hypertrophy with compromised functions in left ventricle pressure, stroke volume, ejection fraction, and overall cardiac output, due to prolong hypertension. The Fe2O3-NPs significantly improved cardiac function in the ciliopathic hypertensive models, which hearts also exhibited arrhythmia but corrected with the Fe2O3-NPs. Fe2O3-NPs significantly improved cardiac function in the Pkd2 mice. Intraciliary and cytosolic Ca2+ were increased when cilia were induced with fluid-flow or magnetic field, and this served as a cilia-dependent mechanism of the Fe2O3-NPs. Fenoldopam-alone caused an immediate decrease in blood pressure, followed by reflex tachycardia. Pharmacological delivery profiles confirmed that the Fe2O3-NPs were a superior delivery system for targeting cilia more specifically, efficiently and effectively than fenoldopam-alone. In summary, we have introduced an approach to remotely control primary cilia. The cilia-targeted magnetic nanoparticles can be used to control non-motile primary cilia movement, length and function. Our studies further indicated that ciliotherapy provides a possibility toward personalized medicine in ciliopathy patients. This nano-formulation can thus be a useful approach for nano-therapy in ciliopathy treatment.