Robust Construction of Supersmall Zwitterionic Micelles Based on Hyperbranched Polycarbonates Mediates High Tumor Accumulation

ROS-responsive core-shell nano-inhibitor impedes pyruvate metabolism for reinforced photodynamic therapy and interrupted pre-metastatic niche formation

The formation of pre-metastatic niche (PMN) in a hospitable organ derived from the primary tumor requires the communication between the tumor cells and the host environment. Pyruvate is a fundamental nutrient by which the tumor cells metabolically reshape the extracellular matrix in the lung to facilitate their own metastatic development. Here we report a combination regimen by integrating the photo-sensitizer and the mitochondrial pyruvate carrier (MPC) inhibitor in a dendritic polycarbonate core-hyaluronic acid shell nano-platform with multivalent reversible crosslinker embedded in it (DOH-NI+L) to reinforce photodynamic therapy (PDT) toward the primary tumor and interrupt PMN formation in the lung via impeding pyruvate uptake. We show that DOH-NI+L mediates tumor-specific MPC inhibitor liberation, inhibiting the aerobic respiration for facilitated PDT and restraining ATP generation for paralyzing cell invasion. Remarkably, DOH-NI+L is demonstrated to block the metabolic crosstalk of tumor cell-host environment by dampening pyruvate metabolism, provoking a series of metabolic responses and resulting in the pulmonary PMN interruption. Consequently, DOH-NI+L realizes a significant primary tumor inhibition and an efficient pulmonary metastasis prevention. Our research extends nano-based anti-metastatic strategies aiming at PMN intervention and such a dendritic core-shell nano-inhibitor provides an innovative paradigm to inhibit tumor growth and prevent metastasis efficiently. STATEMENT OF SIGNIFICANCE: In the progression of cancer metastasis, the formation of a pre-metastatic niche (PMN) in a hospitable organ derived from the primary tumor is one of the rate-limiting stages. The current nano-based anti-metastatic modalities mainly focus on targeted killing of tumor cells and specific inhibition of tumor cell invasion, while nanomedicine-mediated interruption of PMN formation has been rarely reported. Here we report a combination regimen by integrating a photo-sensitizer and an inhibitor of mitochondrial pyruvate carrier in a dendritic core-shell nano-platform with a reversible crosslinker embedded in it to reinforce PDT toward the primary tumor and interrupt PMN formation via impeding the uptake of pyruvate that is a fundamental nutrient facilitating aerobic respiration and PMN formation. Our research proposed a nano-based anti-metastatic strategy aiming at PMN intervention.

Biodegradable Zwitterionic Polymers as PEG Alternatives for Drug Delivery

Poly(ethylene glycol) (PEG) is a highly biocompatible and water-soluble polymer that is widely utilized for biomedical applications. Unfortunately, the immunogenicity and antigenicity of PEG severely restrict the biomedical efficacy of pegylated therapeutics. As emerging PEG alternatives, biodegradable zwitterionic polymers (ZPs) have attracted significant interest in recent years. Biodegradable ZPs generally are not only water-soluble and immunologically inert, but also possess a range of favorable biomedically relevant properties, without causing long-term side effects for in vivo biomedical applications. This review presents a systematic overview of recent studies on biodegradable ZPs. Their structural designs and synthetic strategies by integrating biodegradable base polymers with zwitterions are addressed. Their applications in the delivery of small molecule drugs (as mono-drugs or multi-drugs) and proteins are highlighted.

Cascade-Catalyzed Nanogel for Amplifying Starvation Therapy by Nitric Oxide-Mediated Hypoxia Alleviation

Glucose oxidase (Gox)-mediated starvation therapy offers a prospective advantage for malignancy treatment by interrupting the glucose supply to neoplastic cells. However, the negative charge of the Gox surface hinders its enrichment in tumor tissues. Furthermore, Gox-mediated starvation therapy infiltrates large amounts of hydrogen peroxide (H2O2) to surround normal tissues and exacerbate intracellular hypoxia. In this study, a cascade-catalyzed nanogel (A-NE) was developed to boost the antitumor effects of starvation therapy by glucose consumption and cascade reactive release of nitric oxide (NO) to relieve hypoxia. First, the surface cross-linking structure of A-NE can serve as a bioimmobilization for Gox, ensuring Gox stability while improving the encapsulation efficiency. Then, Gox-mediated starvation therapy efficiently inhibited the proliferation of tumor cells while generating large amounts of H2O2. In addition, covalent l-arginine (l-Arg) in A-NE consumed H2O2 derived from glucose decomposition to generate NO, which augmented starvation therapy on metastatic tumors by alleviating tumor hypoxia. Eventually, both in vivo and in vitro studies indicated that nanogels remarkably inhibited in situ tumor growth and hindered metastatic tumor recurrence, offering an alternative possibility for clinical intervention.

Recent advances in zwitterionic nanoscale drug delivery systems to overcome biological barriers

Nanoscale drug delivery systems (nDDS) have been employed widely in enhancing the therapeutic efficacy of drugs against diseases with reduced side effects. Although several nDDS have been successfully approved for clinical use up to now, biological barriers between the administration site and the target site hinder the wider clinical adoption of nDDS in disease treatment. Polyethylene glycol (PEG)-modification (or PEGylation) has been regarded as the gold standard for stabilising nDDS in complex biological environment. However, the accelerated blood clearance (ABC) of PEGylated nDDS after repeated injections becomes great challenges for their clinical applications. Zwitterionic polymer, a novel family of anti-fouling materials, have evolved as an alternative to PEG due to their super-hydrophilicity and biocompatibility. Zwitterionic nDDS could avoid the generation of ABC phenomenon and exhibit longer blood circulation time than the PEGylated analogues. More impressively, zwitterionic nDDS have recently been shown to overcome multiple biological barriers such as nonspecific organ distribution, pressure gradients, impermeable cell membranes and lysosomal degradation without the need of any complex chemical modifications. The realization of overcoming multiple biological barriers by zwitterionic nDDS may simplify the current overly complex design of nDDS, which could facilitate their better clinical translation. Herein, we summarise the recent progress of zwitterionic nDDS at overcoming various biological barriers and analyse their underlying mechanisms. Finally, prospects and challenges are introduced to guide the rational design of zwitterionic nDDS for disease treatment.

Super-small zwitterionic micelles enable the improvement of blood-brain barrier crossing for efficient orthotopic glioblastoma combinational therapy

Glioblastoma multiforme (GBM) remains incurable in clinical, nanotechnology-based drug delivery strategies show promising perspective in alleviating GBM, while limited blood-brain-barrier (BBB) permeation, short blood half-live accompanied by the poor tumor accumulation and penetration, significantly restrict the therapeutic outcomes. Herein, a versatile super-small zwitterionic nano-system (MCB(S)) based on carboxybetaine (CB) zwitterion functionalized hyperbranched polycarbonate (HPCB) is developed to overcome the brain delivery challenges. After grafting with amino-functionalized IR780 (free IR780), the ultimate paclitaxel (PTX)-encapsulated micelles (MCB(S)-IR@PTX) are precisely activated by near-infrared (NIR) for accelerated drug release and effective combinational GBM therapy. Importantly, MCB(S)-IR@PTX with the crosslinked structure and CB zwitterion prolongs blood-circulation, and CB-zwitterion further facilitates BBB-traversing through betaine/γ-aminobutyric acid (GABA) transporter-1 (BGT-1) pathway. Combined with the benefit of super small-size, MCB(S)-IR@PTX highly accumulates at tumor sites and penetrates deeply, thus efficiently inhibiting tumor growth and strikingly improving survival time in U87MG orthotopic GBM-bearing mouse model. The ingenious nanoplatform furnishes a versatile strategy for delivering therapeutics into the brain and realizing efficient brain cancer therapy.