Multistage Systemic and Cytosolic Protein Delivery for Effective Cancer Treatment.

Current clinical applications of protein therapy are largely limited to systemically accessible targets in vascular or extracellular areas. Major obstacles to the widespread application of protein therapeutics in cancer treatment include low membrane permeability and endosomal entrapment. Herein, we report a multistage nanoparticle (NP) strategy for systemic and cytosolic protein delivery to tumor cells, by encapsulating a protein conjugate, tetra-guanidinium (TG)-modified saporin, into tumor microenvironment (TME) pH-responsive polymeric NPs. Upon reaching the tumor site after systemic circulation, the polymeric NPs respond rapidly to the acidic tumor microenvironment and release the TG-saporin conjugates, which penetrate the tumor tissue and enter into tumor cells via TG-mediated cytosolic transportation. The TG-saproin NPs showed potent inhibition of lung cancer cell growth in vitro and in vivo. We expect that this multistage NP delivery strategy with long blood circulation, deep tumor penetration, and efficient cytosolic transport may be applicable to various therapeutic proteins for effective cancer treatment.

Multistage Adaptive Nanoparticle Overcomes Biological Barriers for Effective Chemotherapy.

Drug delivery systems (DDS) are extensively studied to improve the solubility, stability, pharmacokinetic, and biodistribution of chemotherapeutics. However, the drug delivery efficiency of traditional DDS is often limited by the complicated biological barriers in vivo. Herein, a multistage adaptive nanoparticle (MAN) that simultaneously overcomes multiple biological barriers to achieve tumor-targeted drug delivery with high efficiency is presented. MAN has a core-shell structure, in which both the core and the shell are made of responsive polymers. This structure allows MAN to present different surface properties to adapt to its surrounding biological microenvironment, thereby achieving enhanced stability in blood circulation, improved tumor accumulation and cellular internalization in tumor tissues, and effective release of drug in cells. With these unique characteristics, the MAN loaded with docetaxel achieves effective tumor suppression with reduced systemic toxicity. Furthermore, MAN can load almost any hydrophobic drugs, providing a general strategy for the tumor-targeted delivery of hydrophobic drugs to overcome the multiple biological barriers and improve the efficacy of chemotherapy.

A Gas Therapy Strategy for Intestinal Flora Regulation and Colitis Treatment by Nanogel-Based Multistage NO Delivery Microcapsules.

Current approaches to treating inflammatory bowel disease focus on the suppression of overactive immune responses, the removal of reactive intestinal oxygen species, and regulation of the intestinal flora. However, owing to the complex structure of the gastrointestinal tract and the influence of mucus, current small-molecule and biologic-based drugs for treating colitis cannot effectively act at the site of colon inflammation, and as a result, they tend to exhibit low efficacies and toxic side effects. In this study, nanogel-based multistage NO delivery microcapsules are developed to achieve NO release at the inflammation site by targeting the inflammatory tissues using the nanogel. Surprisingly, oral administration of the microcapsules suppresses the growth of pathogenic bacteria and increases the abundance of probiotic bacteria. Metabolomics further show that an increased abundance of intestinal probiotics promotes the production of metabolites, including short-chain fatty acids and indole derivatives, which modulate the intestinal immunity and restore the intestinal barrier via the interleukin-17 and PI3K-Akt signaling pathways. This work reveals that the developed gas therapy strategy based on multistage NO delivery microcapsules modulates the intestinal microbial balance, thereby reducing inflammation and promoting intestinal barrier repair, ultimately providing a new therapeutic approach for the clinical management of colitis.

TME-Responsive Multistage Nanoplatform for siRNA Delivery and Effective Cancer Therapy.

Since the discovery of RNA interference (RNAi), RNAi technology has rapidly developed into an efficient tool for post-transcriptional gene silencing, which has been widely used for clinical or preclinical treatment of various diseases including cancer. Small interfering RNA (siRNA) is the effector molecule of RNAi technology. However, as polyanionic macromolecules, naked siRNAs have a short circulatory half-life (<15 min) and is rapidly cleared by renal filtration, which greatly hinders their clinical application. Furthermore, the anionic and macromolecular characteristics of naked siRNAs impede their readiness to cross the cell membrane and therefore delivery vehicles are required to facilitate the cellular uptake and cytosolic delivery of naked siRNAs. In the past decade, numerous nanoparticles (NPs) such as liposomes have been employed for in vivo siRNA delivery, which have achieved favorable therapeutic outcomes in clinical disease treatment. In particular, because tumor microenvironment (TME) or tumor cells show several distinguishing biological/endogenous factors (eg, pH, enzymes, redox, and hypoxia) compared to normal tissues or cells, much attention has recently paid to design and construct TME-responsive NPs for multistaged siRNA delivery, which can respond to biological stimuli to achieve efficient in vivo gene silencing and better anticancer effect. In this review, we summarize recent advances in TME-responsive siRNA delivery systems, especially multistage delivery NPs, and discuss their design principles, functions, effects, and prospects.

TME-Responsive Polyprodrug Micelles for Multistage Delivery of Doxorubicin with Improved Cancer Therapeutic Efficacy in Rodents.

It is of great significance to develop multifunctional biomaterials to effectively deliver anticancer drug to tumor cells for cancer therapy. Here, inspired by the specific tumor microenvironment (TME) cues, a unique multistage pH/redox-responsive polyprodrug composed of amphiphilic pH-sensitive diblock copolymer poly(ethylene glycol) methyl ether-b-poly(ß-amino esters) conjugated with doxorubicin (DOX) via redox-sensitive disulfide bonds (mPEG-b-PAE-ss-DOX) is designed and developed. This polyprodrug can self-assemble into micelles (DOX-ss@PMs) at low concentration with high serum stability, indicating that DOX-ss@PMs have prolonged circulation time. The dual pH/redox-responsiveness of the multistage platform is thoroughly evaluated. In vitro results demonstrate that DOX-ss@PMs can highly accumulate at tumor site, followed by responding to the acidity for disassembly and effectively penetrating into the tumor cells. DOX is released from the platform due to the cleavage of disulfide bonds induced by high glutathione (GSH) concentration, thereby inducing the apoptosis of tumor cells. In vivo studies further reveal that multistage DOX-ss@PMs can more efficiently inhibit the growth of tumors and improve the survival of tumor-bearing mice in comparison to the free drug and control. These results imply that multistage delivery system might be a potential and effective strategy for drug delivery and DOX-ss@PMs could be a promising nanomedicine for cancer chemotherapy.

Multistage Delivery Nanoparticle Facilitates Efficient CRISPR/dCas9 Activation and Tumor Growth Suppression In Vivo.

CRISPR/dCas9 systems can precisely control endogenous gene expression without interrupting host genomic sequence and have provided a novel and feasible strategy for the treatment of cancers at the transcriptional level. However, development of CRISPR/dCas9-based anti-cancer therapeutics remains challenging due to the conflicting requirements for the design of the delivery system: a cationic and membrane-binding surface facilitates the tumor accumulation and cellular uptake of the CRISPR/dCas9 system, but hinders the circulating stability in vivo. Here, a multistage delivery nanoparticle (MDNP) that can achieve tumor-targeted delivery of CRISPR/dCas9 systems and restore endogenous microRNA (miRNA) expression in vivo is described. MDNP is designed as a core-shell structure in which the shell is made of a responsive polymer that endows MDNP with the capability to present different surface properties in response to its surrounding microenvironment, allowing the MNDP overcoming multiple physiological barriers and delivering the payload to tumor tissues with an optimal efficiency. Systemic administration of MDNP/dCas9-miR-524 to tumor-bearing mice achieved effective upregulation of miR-524 in tumors, leading to the simultaneous interferences of multiple signal pathways related to cancer cell proliferation and presenting remarkable tumor growth retardation, suggesting the feasibility of utilizing MDNP to achieve tumor-targeting delivery of CRISPR/dCas9 with sufficient levels to realize its therapeutic effects.