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

在这项研究中，我们研究了一种可生物降解的水凝胶，聚D，L-乳酸-对二氧杂环己酮-聚乙二醇嵌段共聚物作为小干扰RNA载体的效果。将带有或不带有荧光素标记的dsRNA的聚乳酸-DX-聚乙二醇微丸植入小鼠背侧肌袋内。荧光显微镜证实了聚合物周围细胞对dsRNA的摄取。荧光强度与dsRNA呈剂量依赖关系，并呈时间依赖性降低。为了研究其生物学效应，采用siRNA技术检测了BMPs拮抗剂noggin(siRNA/noggin)对BMP-2诱导的noggin基因表达的抑制量和异位成骨能力。在种植体中加入siRNA/Noggin可抑制BMP-2诱导的noggin基因表达，BMP-2和siRNA/Noggin复合种植体诱导的异位骨形成明显高于单独BMP-2种植体诱导的异位成骨。这些结果表明，聚乳酸-DX-聚乙二醇共聚物局部注射siRNAs可增强BMP的成骨作用，并通过抑制Noggin基因的表达促进新骨形成。

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.