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Nanoparticle-mediated SiRNA/miRNA Delivery to Mesenchymal Stem Cells

出版	University of Rochester, 2017
URL	http://books.google.com.hk/books?id=oTT7vQEACAAJ&hl=&source=gbs_api

註釋"Small interfering RNA (siRNA) and microRNA (miRNA) are short double stranded RNA molecules that mediate posttranscriptional gene silencing via RNA interference by binding to or degrading complimentary target mRNA in the cytosol to inhibit translation. Though> 30 siRNA and miRNA candidates are in clinical trials for a variety of indications, none have yet to receive FDA-approval. Successful delivery is the critical barrier to therapeutic translation, and necessitates the need for multifunctional drug delivery systems (DDS). Barriers to delivery include nuclease-mediated degradation and phospholipid membrane impermeability. Furthermore, any DDS used must be cytocompatible and avoid off-target effects. The study herein provides a comprehensive characterization of a pH-responsive diblock copolymer nanoparticle (NP) siRNA DDS and its effects on mesenchymal stem cells (MSCs) for applications in regenerative medicine. Reversible addition-fragmentation chain transfer (RAFT) polymerization was used to synthesize a library of diblock copolymers to determine how polymer properties affect siRNA delivery. Results show this NP-siRNA delivery is effective in multiple therapeutic cell types in vitro, and that increasing NP core hydrophobicity provides greater cytocompatibility and gene silencing. This is achieved by increased pHresponsive membrane lytic activity allowing for better endosomal escape. Additionally, in vitro treatment conditions were identified that resulted in potent gene silencing with no acute cytotoxicity. However, NP-siRNA treatment resulted in a sustained reduction in hMSC metabolic activity, and RNAseq with enrichment analysis shows upregulation of anti-apoptotic gene expression and immune signaling pathways associated with siRNA immune stimulation. Colloidal stability is critical for effective NP DDS, and can be significantly altered in the presence of biological proteins. Therefore, an extensive characterization of this NP-siRNA DDS in the presence of serum reveals NP-siRNA aggregation, which significantly diminishes siRNA delivery in vitro. When delivered locally in vivo, cells take up NP-siRNA complexes in a non-aggregated state, emphasizing the importance of local delivery. Taken together this in-depth characterization of NP-mediated siRNA delivery establishes a solid foundation for the design of next generation NP-siRNA DDS for the delivery of siRNA/miRNA to MSCs."--Pages xiv-xv