A pH-/Enzyme-Responsive Nanoparticle Selectively Targets Endosomal Toll-like Receptors to Potentiate Robust Cancer Vaccination.

Toll-like receptor (TLR) agonists are potent immune-stimulators that hold great potential in vaccine adjuvants as well as cancer immunotherapy. However, TLR agonists in free form are prone to be eliminated quickly by the circulatory system and cause systemic inflammation side effects. It remains a challenge to achieve precise release of TLR7/8 agonist in the native form at the receptor site in the endosomal compartments while keeping stable encapsulation and inactive in nontarget environment. Here, we report a pH-/enzyme-responsive TLR7/8 agonist-conjugated nanovaccine (TNV), which responds intelligently to the acidic environment and cathepsin B in the endosome, precisely releases TLR7/8 agonist to activate its receptor signaling at the endosomal membrane, stimulates DCs maturation, and provokes specific cellular immunity. In vivo experiments demonstrate outstanding prophylactic and therapeutic efficacy of TNV in mouse melanoma and colon cancer. The endosome-targeted responsive nanoparticle strategy provides a potential delivery toolbox of adjuvants to advance the development of tumor nanovaccines.

A pH-Responsive Nanoparticle Library with Precise pH Tunability by Co-Polymerization with Non-Ionizable Monomers.

Precise monitoring of the subtle pH fluctuation during biological events remains a big challenge. Previously, we reported an ultra-pH-sensitive (UPS) nanoprobe library with a sharp pH response using co-polymerization of two tertiary amine-containing monomers with distinct pKa . Currently, we have generalized the UPS nanoparticle library with tunable pH transitions (pHt ) by copolymerization of a tertiary amine-containing monomer with a series of non-ionizable monomers. The pHt of nanoparticles is fine-tuned by the non-ionizable monomers with different hydrophobicity. Each non-ionizable monomer presents a constant contribution to pH tunability regardless of tertiary amine-containing monomers. Based on this strategy, we produced two libraries of nanoprobes with continuous pHt covering the entire physiological pH range (5.0-7.4) for fluorescent imaging of endosome maturation and cancers. This generalized strategy provides a powerful toolkit for biological studies and cancer theranostics.

pH-gated nanoparticles selectively regulate lysosomal function of tumour-associated macrophages for cancer immunotherapy.

Tumour-associated macrophages (TAMs), as one of the most abundant tumour-infiltrating immune cells, play a pivotal role in tumour antigen clearance and immune suppression. M2-like TAMs present a heightened lysosomal acidity and protease activity, limiting an effective antigen cross-presentation. How to selectively reprogram M2-like TAMs to reinvigorate anti-tumour immune responses is challenging. Here, we report a pH-gated nanoadjuvant (PGN) that selectively targets the lysosomes of M2-like TAMs in tumours rather than the corresponding organelles from macrophages in healthy tissues. Enabled by the PGN nanotechnology, M2-like TAMs are specifically switched to a M1-like phenotype with attenuated lysosomal acidity and cathepsin activity for improved antigen cross-presentation, thus eliciting adaptive immune response and sustained tumour regression in tumour-bearing female mice. Our findings provide insights into how to specifically regulate lysosomal function of TAMs for efficient cancer immunotherapy.

A pyroptosis nanotuner for cancer therapy.

Pyroptosis is a gasdermin-mediated programmed necrosis that occurs via membrane perforation and that can be exploited for biomedical applications in cancer therapy. However, inducing specific pyroptotic cancer cell death while sparing normal cells is challenging. Here, we report an acid-activatable nanophotosensitizer library that can be used to spatiotemporally target distinct stages of endosomal maturation, enabling tunable cellular pyroptosis. Specific activation of phospholipase C signalling transduction in early endosomes triggers gasdermin-E-mediated pyroptosis, which is dramatically reduced when acid-activatable nanophotosensitizers are transported into late endosomes/lysosomes. This nanotuner platform induces pyroptotic cell death with up to 40-fold tunability in various gasdermin-E-positive human cancers, resulting in enhanced anti-tumour efficacy and minimized systemic side effects. This study offers new insights into how to engineer nanomedicines with tunable pyroptosis activity through specific targeting of distinct endocytic signalling for biomedical applications.

Dissecting extracellular and intracellular distribution of nanoparticles and their contribution to therapeutic response by monochromatic ratiometric imaging.

Efficient delivery of payload to intracellular targets has been identified as the central principle for nanomedicine development, while the extracellular targets are equally important for cancer treatment. Notably, the contribution of extracellularly distributed nanoparticles to therapeutic outcome is far from being understood. Herein, we develop a pH/light dual-responsive monochromatic ratiometric imaging nanoparticle (MRIN), which functions through sequentially lighting up the intracellular and extracellular fluorescence signals by acidic endocytic pH and near-infrared light. Enabled by MRIN nanotechnology, we accurately quantify the extracellular and intracellular distribution of nanoparticles in several tumor models, which account for 65-80% and 20-35% of total tumor exposure, respectively. Given that the majority of nanoparticles are trapped in extracellular regions, we successfully dissect the contribution of extracellularly distributed nanophotosensitizer to therapeutic efficacy, thereby maximize the treatment outcome. Our study provides key strategies to precisely quantify nanocarrier microdistribtion and engineer multifunctional nanomedicines for efficient theranostics.

Sequential Modulations of Tumor Vasculature and Stromal Barriers Augment the Active Targeting Efficacy of Antibody-Modified Nanophotosensitizer in Desmoplastic Ovarian Carcinoma.

Active-targeted nanoparticles are attractive carriers due to their potentials to facilitate specific delivery of drugs into tumor cells while sparing normal cells. However, the therapeutic outcomes of active-targeted nanomedicines are hampered by the multiple physiological barriers in the tumor microenvironment (TME). Herein, an epidermal growth factor receptor-targeted ultra-pH-sensitive nanophotosensitizer is fabricated, and the regulation of the TME to augment the active targeting ability and therapeutic efficacy is pinpointed. The results reveal that tumor vasculature normalization with thalidomide indiscriminately enhance the tumor accumulation of passive and active targeted nanoparticles, both of which are sequestered in the stromal bed of tumor mass. Whereas, photoablation of stromal cells located in perivascular regions significantly improves the accessibility of antibody-modified nanophotosensitizer to receptor-overexpressed cancer cells. After sequential regulation of TME, the antitumor efficacy of antibody-modified nanophotosensitizer is drastically enhanced through synergistic enhancements of tumor accumulation and cancer cell accessibility of active-targeted nanoparticles. The study offers deep insights about the intratumoral barriers that hinder the active-targeted nanoparticles delivery, and provides a basis for developing more effective strategies to accelerate the clinical translation of active-targeted nanomedicines.

Quick-Responsive Polymer-Based Thermosensitive Liposomes for Controlled Doxorubicin Release and Chemotherapy.

Thermosensitive liposomes (TSLs) have been widely investigated for controlled drug release at specific pathophysiological sites. Although excellent thermo-sensitivity under hyperthermia (HT) was already realized for TSLs, their in vivo stability under physiological temperature still remains challenging. To overcome this limitation, optimized polymer-based thermosensitive liposomes (P-TSLs) with good thermo-sensitivity as well as satisfactory in vivo stability were developed in this study for tumor-specific controlled delivery of doxorubicin (DOX). In particular, polymers including p(NIPAM-r-HPMA) and p(HPMA-r-APMA) were successfully synthesized based on a reversible addition-fragmentation chain transfer (RAFT) technique. Next, thermosensitive polymer p(NIPAM-r-HPMA) was first proposed to be inserted into the lipid bilayer of TTSL by a postinsertion method. The resulting P-TTSL had a phase transition temperature (Tm) of around 42 °C and displayed excellent thermo-sensitivity under HT: nearly 70% of DOX was released within 1 min when only 1% p(NIPAM-r-HPMA) was incorporated. Moreover, its stability was maintained at 37 °C. Compared with TTSL, significantly higher cellular uptake of DOX under HT was noticed in P-TTSL, indicating a burst release of DOX at 42 °C. In addition, both in vitro tumor spheroid experiments and in vivo tumor slices demonstrated an enhanced DOX deep penetration when treated by P-TTSL under HT. To achieve in vivo imaging and local HT under NIR, p (HPMA-r-APMA) was labeled by Cy7.5 and coinserted into TTSL, and the best drug efficacy was observed in CY-P-TTSL with HT along with prolonged blood circulation time. We have further investigated the biocompatibility of the developed CY-P-TTSL, and reduced cardiotoxicity was observed even under HT in comparison with free DOX, demonstrating it is a reliable thermosensitive drug carrier for improving drug stability and therapeutic efficacy.