Local delivery of small interfering RNA using biodegradable polymer application to enhance bone morphogenetic protein-induced bone formation

在这项研究中，我们研究了可生物降解的水凝胶聚d， l -乳酸-对二氧环酮-聚乙二醇嵌段共聚物（PLA-DX-PEG）作为siRNA载体的功效。将带或不带荧光素标记的dsRNA的PLA-DX-PEG微球植入小鼠剂量肌袋。荧光显微镜证实了聚合物周围的dsRNA的细胞摄取。荧光强度与dsRNA的剂量有关，并呈时间依赖性下降。为了研究其生物学效率，我们用siRNA沉默noggin （BMP拮抗剂）基因（siRNA/ noggin），通过BMP-2诱导的noggin表达的抑制量和BMP的表现水平（异位骨形成）进行了检测。在植入物中加入siRNA/Noggin可抑制BMP-2诱导的Noggin基因表达，同时加入BMP-2和siRNA/Noggin诱导的异位骨形成明显大于单独加入BMP-2诱导的异位骨形成。这些结果表明，PLA-DX-PEG聚合物局部递送sirna的有效性，通过抑制Noggin基因的表达，增强了BMP的骨诱导作用，促进了新骨的形成。

In this study, we investigated the efficacy of a biodegradable hydrogel, poly-D,L-lactic acid-p-dioxanone-polyethylene glycol block co-polymer (PLA-DX-PEG), as a siRNA carrier. PLA-DX-PEG pellets with or without fluorescein-labeled dsRNA were implanted into mouse dosal muscle pouches. The cellular uptake of dsRNA surround the polymer was confirmed by fluorescent microscopy. The fluorescence intensity was dose dependent of the dsRNA, and exhibited a time-dependent decrease. To investigate its biological efficiency, noggin (antagonoist to BMPs) gene silencing with siRNA (siRNA/Noggin) was examined by the amount of suppression of BMP-2-induced noggin expression and the level of performance of BMP, indicated by ectopic bone formation. Noggin gene expression induced by BMP-2 was suppressed by addition of siRNA /Noggin to the implant, and the ectopic-bone formation induced by implants with both BMP-2 and siRNA/Noggin was significantly greater than those induced by implants with BMP-2 alone. These results indicate the efficacy of local delivery of siRNAs by PLA-DX-PEG polymer, which intensified bone-inducing effects of BMP and promoted new bone formation by suppressing gene expression of Noggin.