Mesoporous nanocarriers with internal cavity for the delivery of siRNA for bone regeneration

Abstract

Event Abstract Back to Event Mesoporous nanocarriers with internal cavity for the delivery of siRNA for bone regeneration Jungju Kim1, 2, Tsendmaa Bold1, 2, Jeong-Hyun Ryu1, 2, Roman Perez1, 2 and Hae-Won Kim1, 2, 3 1 dankook university, Tissue Regeneration Engineering, Korea 2 dankook university, Nanobiomedical Science & BK21 PLUS NBM Global Research Center for Regenerative Medicine, Korea 3 dankook university, Biomaterials Science, College of Dentistry, Korea Introduction: Nanocarriers have great interest in the field of tissue engineering for the delivery of drugs and genes. Among other issues, the loading of those molecules in sufficient amount and the sustained release are considered of special importance for therapeutic efficacy of the delivery system. For this purpose, we developed a mesoporous silica nanocarrier with an internal cavity to allow high loading capacity and sustained delivery of small interference RNA (siRNA). Here, we delivered siRNA to downregulate Plekho-1 gene, which has been shown to significantly enhance bone regeneration. We investigated the ability to load and release the siRNA as well as the cellular interaction and osteogenic potential. Materials and Methods: Apatite nanorods were used as sacrifice core templates which were then sheathed with mesoporous silica through a sol-gel reaction. Apatite was then selectively removed by an acid treatment. The surface of the nanocarriers was aminated with APTES for proper siRNA loading. The nanocarriers were characterized by transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), Fourier transform infrared spectroscopy (FT-IR), and Brunauer Emmett Teller (BET). The loading and delivery of the siRNA was quantified in the range of 10 to 100 µg/ml. In order to observe cellular interactions, pre-osteoblastic cells were cultured with the siRNA-loaded nanocarriers at the different siRNA concentrations. The cell viability, intracellular uptake capacity, gene silencing efficiency, and bone-related gene expressions were investigated. Results and Discussion: Mesoporous and internally-hollowed silica nanocarriers were produced well, as observed by TEM images, which presenting an internal cavity of ~20 nm. Compared to the dense nanocarriers, the surfaces area and pore volume of developed nanocarriers. Due to the enhanced surface area and pore volume, the siRNA loading capacity increased 5-fold. The unique pore morphology and characteristics allowed sustained release of the siRNA from the developed nanocarriers for up to 18 days, which was significantly different from the dense nanocarriers which completely released the cargo after only 3 days. Cellular viability of the developed nanocarriers was high for the studied concentrations, allowing therefore high doses of the nanocarriers and the loading of siRNA to be delivered. The siRNA-loaded nanocarriers were successfully taken up by the pre-osteoblastic cells, with a cellular uptake ~90%, and silenced the expression of the target gene by 80%, which subsequently induced an upregulation of osteoblasts-related genes. Conclusion: Mesoporous nanocarriers with an internal cavity showed the capacity of high loading and sustained release of siRNA molecules. The siRNA-delivering nanocarriers successfully downregulated Plekho-1 target genes while upregulating osteogenic genes in vitro. Further in vivo study remains to investigate the practical efficacy of the nanocarriers for bone regeneration.