Multifunctional Natural Polymer Nanoparticles as Antifibrotic Gene Carriers for CKD Therapy
Authors: Midgley Adam C. , Wei Yongzhen , Zhu Dashuai , Gao Fangli , Yan Hongyu , Khalique Anila , Luo Wenya , Jiang Huan , Liu Xiangsheng , Guo Jiasen , Zhang Chuangnian , Feng Guowei , Wang Kai , Bai Xueyuan , Ning Wen , Yang Chao , Zhao Qiang , Kong Deling 
Published: August 2020

Significance Statement
Progressive fibrosis, the underlying pathophysiologic process of CKD, is driven by myofibroblasts and activated profibrotic cells. Treatments targeting these cells for the reversal and amelioration of CKD are lacking. Experimental cytokine therapies administered locally are constrained by low bioavailability and transient activity, but nanoparticles can circumvent this and offer noninvasive kidney-targeted delivery of antifibrotic biologics, such as bone morphogenetic protein 7 (BMP7) and hepatocyte growth factor (HGF)–NK1 (HGF/NK1). The authors used nanoparticles containing plasmid DNA expressing either BMP7 or NGF/NKI enclosed in biocompatible natural materials for intravenous delivery of gene therapy to CKD mouse models. Delivery of BMP7 reversed the progression of fibrosis and regenerated tubules; delivery of HGF/NK1 halted CKD progression by eliminating collagen fiber deposition. Nanoparticle gene therapy shows potential as a noninvasive approach to treat CKD.

Background
Progressive fibrosis is the underlying pathophysiological process of CKD, and targeted prevention or reversal of the profibrotic cell phenotype is an important goal in developing therapeutics for CKD. Nanoparticles offer new ways to deliver antifibrotic therapies to damaged tissues and resident cells to limit manifestation of the profibrotic phenotype.

Methods
We focused on delivering plasmid DNA expressing bone morphogenetic protein 7 (BMP7) or hepatocyte growth factor (HGF)–NK1 (HGF/NK1) by encapsulation within chitosan nanoparticles coated with hyaluronan, to safely administer multifunctional nanoparticles containing the plasmid DNA to the kidneys for localized and sustained expression of antifibrotic factors. We characterized and evaluated nanoparticles in vitro for biocompatibility and antifibrotic function. To assess antifibrotic activity in vivo, we used noninvasive delivery to unilateral ureteral obstruction mouse models of CKD.

Results
Synthesis of hyaluronan-coated chitosan nanoparticles containing plasmid DNA expressing either BMP7 or NGF/NKI resulted in consistently sized nanoparticles, which—following endocytosis driven by CD44+ cells—promoted cellular growth and inhibited fibrotic gene expression in vitro. Intravenous tail injection of these nanoparticles resulted in approximately 40%–45% of gene uptake in kidneys in vivo. The nanoparticles attenuated the development of fibrosis and rescued renal function in unilateral ureteral obstruction mouse models of CKD. Gene delivery of BMP7 reversed the progression of fibrosis and regenerated tubules, whereas delivery of HGF/NK1 halted CKD progression by eliminating collagen fiber deposition.

Conclusions
Nanoparticle delivery of HGF/NK1 conveyed potent antifibrotic and proregenerative effects. Overall, this research provided the proof of concept on which to base future investigations for enhanced targeting and transfection of therapeutic genes to kidney tissues, and an avenue toward treatment of CKD.