Despite several decades of progress, bone-specific drug delivery is still a major challenge. Current bone-acting drugs require high-dose systemic administration which decreases therapeutic efficacy and increases off-target tissue effects. Here, a bone-targeted nanoparticle (NP) delivery system for a β-catenin agonist, 3-amino-6-(4-((4-methylpiperazin-1-yl)sulfonyl)phenyl)-N-(pyridin-3-yl)pyrazine-2-carboxamide, a glycogen synthase kinase 3 beta (GSK-3β) inhibitor, was developed to enhance fracture healing. The GSK-3β inhibitor loading capacity was found to be 15 wt % within highly stable poly(styrene-alt-maleic anhydride)-b-poly(styrene) NPs, resulting in ∼50 nm particles with ∼ –30 mV surface charge. A peptide with high affinity for tartrate-resistant acid phosphatase (TRAP), a protein deposited by osteoclasts on bone resorptive surfaces, was introduced to the NP corona to achieve preferential delivery to fractured bone. Targeted NPs showed improved pharmacokinetic profiles with greater accumulation at fractured bone, accompanied by significant uptake in regenerative cell types (mesenchymal stem cells (MSCs) and osteoblasts). MSCs treated with drug-loaded NPs in vitro exhibited 2-fold greater β-catenin signaling than free drug that was sustained for 5 days. To verify similar activity in vivo, TOPGAL reporter mice bearing fractures were treated with targeted GSK-3β inhibitor-loaded NPs. Robust β-galactosidase activity was observed in fracture callus and periosteum treated with targeted carriers versus controls, indicating potent β-catenin activation during the healing process. Enhanced bone formation and microarchitecture were observed in mice treated with GSK-3β inhibitor delivered via TRAP-binding peptide-targeted NPs. Specifically, increased bone bridging, ∼4-fold greater torsional rigidity, and greater volumes of newly deposited bone were observed 28 days after treatment, indicating expedited fracture healing.

中文翻译：

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通过肽功能化的纳米粒子增强β-连环蛋白激动剂的骨折靶向递送。

尽管取得了几十年的进步，但骨特异性药物的递送仍然是一个重大挑战。当前的骨作用药物需要大剂量全身给药，这降低了治疗功效并增加了脱靶组织的作用。在这里，为β-catenin激动剂3-氨基-6-（4-（（（4-甲基哌嗪-1-基）磺酰基）苯基）-N-（吡啶-3-开发一种糖原合酶激酶3β（GSK-3β）抑制剂yl）pyrazine-2-carboxamide，以增强骨折愈合。的GSK-3β抑制剂负载能力被发现高度稳定的聚内为15％（重量）（苯乙烯- ALT -马来酸酐） - B-聚（苯乙烯）NP，产生约50 nm的粒子，其表面电荷约为–30 mV。与抗酒石酸酸性磷酸酶（TRAP）具有高亲和力的肽（破骨细胞沉积在骨吸收表面上的蛋白质）被引入NP电晕，以实现优先递送至骨折的骨。靶向的NPs显示出改善的药代动力学特征，在骨折处具有更大的积累，并伴随着对再生细胞类型（间充质干细胞（MSCs）和成骨细胞）的大量摄取。在体外用载有药物的NPs处理的MSC的β-catenin信号强度比持续5天的游离药物高2倍。验证体内相似的活性，将带有骨折的TOPGAL报告基因小鼠用靶向GSK-3β抑制剂的NP进行治疗。与对照相比，在用靶向载体治疗的骨call和骨膜中观察到了强大的β-半乳糖苷酶活性，这表明在愈合过程中有效的β-catenin活化。在用经TRAP结合肽靶向的NP递送的GSK-3β抑制剂治疗的小鼠中观察到增强的骨形成和微结构。具体而言，治疗后28天观察到骨桥增加，抗扭刚度提高约4倍，并且新沉积的骨量更大，表明骨折愈合加快。