Enhanced Tumor Site Accumulation and Therapeutic Efficacy of Extracellular Matrix-Drug Conjugates Targeting Tumor Cells.

The extracellular matrix (ECM) engages in regulatory interactions with cell surface receptors through its constituent proteins and polysaccharides. Therefore, nano-sized extracellular matrix conjugated with doxorubicin (DOX) is utilized to produce extracellular matrix-drug conjugates (ECM-DOX) tailored for targeted delivery to cancer cells. The ECM-DOX nanoparticles exhibit rod-like morphology, boasting a commendable drug loading capacity of 4.58%, coupled with acid-sensitive drug release characteristics. Notably, ECM-DOX nanoparticles enhance the uptake by tumor cells and possess the ability to penetrate endothelial cells and infiltrate tumor multicellular spheroids. Mechanistic insights reveal that the internalization of ECM-DOX nanoparticle is facilitated through clathrin-mediated endocytosis and macropinocytosis, intricately involving hyaluronic acid receptors and integrins. Pharmacokinetic assessments unveil a prolonged blood half-life of ECM-DOX nanoparticles at 3.65 h, a substantial improvement over the 1.09 h observed for free DOX. A sustained accumulation effect of ECM-DOX nanoparticles at tumor sites, with drug levels in tumor tissues surpassing those of free DOX by several-fold. The profound therapeutic impact of ECM-DOX nanoparticles is evident in their notable inhibition of tumor growth, extension of median survival time in animals, and significant reduction in DOX-induced cardiotoxicity. The ECM platform emerges as a promising carrier for avant-garde nanomedicines in the realm of cancer treatment.

Targeting Inflammatory Lesions Facilitated by Galactosylation Modified Delivery System Eudragit/Gal-PLGA@Honokiol for the treatment of Ulcerative Colitis.

Honokiol (HNK) is one of the bioactive ingredients from the well-known Chinese herbal medicine Magnolia officinalis, and its research interests is rising for its extensive pharmacological activities, including novel therapeutic effect on ulcerative colitis (UC). However, further application of HNK is largely limited by its unique physicochemical properties, such as poor water solubility, low bioavailability, as well as unsatisfied targeting efficacy for inflammatory lesions. In this study, we constructed galactosylation modified PLGA nanoparticles delivery system for efficient target delivery of HNK to the colitic lesions, which could lay a research foundation for the deep development of HNK for the treatment of UC. D-galactose was grafted by chemical coupling reactions with PLGA to prepare Gal-PLGA, which was used as a carrier for HNK (Gal-PLGA@HNK nanoparticles (NPs)). To improve the colon targeting efficiency by oral administration of the NPs, Eudragit S100 was used for wrapping on the surface of Gal-PLGA@HNK NPs (E/Gal-PLGA@HNK NPs). Our results showed that the encapsulation efficiency and drug loading capacity of E/Gal-PLGA@HNK NPs were 90.72 ± 0.54% and 8.41 ± 0.02%, respectively. Its average particle size was 242.24 ± 8.42 nm, with a PDI value of 0.135 ± 0.06 and zeta-potential of -16.83 ± 1.89 mV. The release rate of HNK from E/Gal-PLGA@HNK NPs was significantly decreased when compared with that of free HNK in simulated gastric and intestinal fluids, which displayed a slow-releasing property. It was also found that the cellular uptake of E/Gal-PLGA@HNK NPs was significantly increased when compared with that of free HNK in RAW264.7 cells, which was facilitated by D-galactose grafting on the PLGA carrier. Additionally, our results showed that E/Gal-PLGA@HNK NPs significantly improved colonic atrophy, body weight loss, as well as reducing disease activity index (DAI) score and pro-inflammatory cytokine levels in UC mice induced by DSS. Besides, the retention time of E/Gal-PLGA@HNK NPs in the colon was significantly increased when compared with that of other preparations, suggesting that these NPs could prolong the interaction between HNK and the injured colon. Taken together, the efficiency for target delivery of HNK to the inflammatory lesions was significantly improved by galactosylation modification on the PLGA carrier, which provided great benefits for the alleviation of colonic inflammation and injury in mice.

Destruction of vascular endothelial glycocalyx during formation of pre-metastatic niches.

A special microenvironment called the "pre-metastatic niche" is thought to help primary tumor cells migrate to new tissues and invade them, in part because the normal barrier function of the vascular endothelium is compromised. While the primary tumor itself can promote the creation of such niches by secreting pro-metastatic factors, the underlying molecular mechanisms are still poorly understood. Here, we show that the injection of primary tumor-secreted pro-metastatic factors from B16F10 melanoma or 4T1 breast cancer cells into healthy mice can induce the destruction of the vascular endothelial glycocalyx, which is a polysaccharide coating on the vascular endothelial lumen that normally inhibits tumor cell passage into and out of the circulation. However, when human umbilical vein endothelial cultures were treated in vitro with these secreted pro-metastatic factors, no significant destruction of the glycocalyx was observed, implying that this destruction requires a complex in vivo microenvironment. The tissue section analysis revealed that secreted pro-metastatic factors could clearly upregulate macrophage-related molecules such as CD11b and tumor necrosis factor-α (TNF-α) in the heart, liver, spleen, lung, and kidney, which is associated with the upregulation and activation of heparanase. In addition, macrophage depletion significantly attenuated the degradation of the vascular endothelial glycocalyx induced by secreted pro-metastatic factors. This indicates that the secreted pro-metastatic factors that destroy the vascular endothelial glycocalyx rely primarily on macrophages. Our findings suggest that the formation of pre-metastatic niches involves degradation of the vascular endothelial glycocalyx, which may hence be a useful target for developing therapies to inhibit cancer metastasis.

Constructing Tumor Organoid-like Tissue for Reliable Drug Screening Using Liver-Decellularized Extracellular Matrix Scaffolds.

The interplay between cells and their microenvironments plays a pivotal role in in vitro drug screening. Creating an environment that faithfully mimics the conditions of tumor cells within organ tissues is essential for enhancing the relevance of drug screening to real-world clinical scenarios. In our research, we utilized chemical decellularization techniques to engineer liver-decellularized extracellular matrix (L-dECM) scaffolds. These scaffolds were subsequently recellularized with HepG2 cells to establish a tumor organoid-like tissue model. Compared to the conventional tissue culture plate (TCP) culture, the tumor organoid-like tissue model demonstrated a remarkable enhancement in HepG2 cell growth, leading to increased levels of albumin secretion and urea synthesis. Additionally, our results revealed that, within a 3-day time frame, the cytotoxicity of doxorubicin (DOX) against cells cultured in the tumor organoid-like tissue model was notably reduced when compared to cells grown on TCPs. In contrast, there was no significant difference in the cytotoxicity of two compounds, triptolide and honokiol, both derived from traditional Chinese medicine, between TCP culture and the tumor organoid-like tissue culture, indicating a lack of substantial drug resistance. Western blotting assays further confirmed our findings by revealing elevated expressions of E-cadherin and vimentin proteins, which are closely associated with the epithelial-mesenchymal transition (EMT). These results underscored that the tumor organoid-like tissue model effectively promoted the EMT process in HepG2 cells. Moreover, we identified that triptolide and honokiol possess the capacity to reverse the EMT process in HepG2 cells, whereas DOX did not exhibit a significant effect. In light of these findings, the tumor organoid-like tissue model stands as a valuable predictive platform for screening antitumor agents and investigating the dynamics of the EMT process in tumor cells.

Co-delivery of microRNA-150 and quercetin by lipid nanoparticles (LNPs) for the targeted treatment of age-related macular degeneration (AMD).

Age-related macular degeneration (AMD) is characterized by choroidal neovascularization (CNV), which leads to severe vision loss in middle-aged and elderly patients. Current treatments for CNV show weak, transient efficacy, and they can cause several adverse effects. A potential new treatment is to use microRNA-150 (mR150), which regulates physiological and pathological angiogenesis by modulating the expression of CXCR4 at the post-transcriptional level. Here, we developed solid lipid nanoparticles that we modified with an Asp-Gly-Arg peptide to target endothelial cells during abnormal angiogenesis, then we co-loaded them with mR150 and the anti-angiogenic drug quercetin. The resulting nanoparticles had an average size around 200 nm and showed strong ability to target the fundus and inhibit CNV for up to two weeks in a mouse model without causing retinal toxicity. They significantly enhanced the uptake of mR150 in vitro compared to free mR150 or nanoparticles without peptide. Our study suggests that co-administration of mR150 and quercetin has potential for treating age-related macular degeneration and that nanoparticles modified with Asp-Gly-Arg peptide are an effective platform for the co-delivery of small-molecule and nucleic acid drugs via intravitreal injection.

Antibody-based drug delivery systems for cancer therapy: Mechanisms, challenges, and prospects.

In recent years, antibody-based cancer therapy has emerged as one of the efficient therapeutic strategies, such as immune checkpoint inhibitors (ICIs), angiogenesis inhibitors, antibody-drug conjugates (ADCs), multi-specific antibodies, and chimeric antigen receptor T (CAR-T) cells, among others. To date, various drug delivery platforms have been developed to improve the bioavailability, delivery convenience, and reduced toxicity towards increased therapeutic efficacy of antibodies. Herein, we emphasize the clinical manifestations of various antibody-based tumor therapies, highlighting their mechanisms and applications for cancer therapy. Further, based on the problems to be solved in the current clinical application of antibodies, and combined with the advanced drug delivery technologies, we discuss the roles of antibody-based drug delivery systems (DDSs) in cancer therapy, such as enhanced patient compliance and regulating the tumor microenvironment for combined therapy. By expounding the importance of DDSs and discussing the challenges and prospects of their implementation, we suggest that pharmaceutical enterprises and scientists develop appropriate antibody-based delivery platforms.

Antibody and Cellular-Based Therapies for Pediatric Acute Lymphoblastic Leukemia: Mechanisms and Prospects.

BACKGROUND: Acute lymphoblastic leukemia (ALL) is one of the most commonly diagnosed cancers in children. Despite enormous efforts to treat ALL over the past decade, the intensity of conventional chemotherapeutic strategies has reached the tolerance limit. Among various recently developed therapeutic approaches, antibody and cellular-based therapies showed less toxicity and better curative effect. SUMMARY: Due to advanced mechanistic actions, these innovative therapies have provided durable responses and long-term survival in eradicating pediatric ALL, especially patients with refractory/relapsed ALL. Owing to these aspects, herein, we emphasize the mechanisms of action and application status of antibodies targeting tumor antigens, antibody-drug conjugates, bispecific antibodies, and chimeric antigen receptor T cells. KEY MESSAGES: The significant prospects and challenges are discussed, highlighting the innovative immunotherapies to deal with ALL. Together, this review will summarize the progress of antibody and cellular-based therapies for pediatric ALL, which may promote further research on antibody-based biopharmaceutics.

3D bioprinting of conductive hydrogel for enhanced myogenic differentiation.

Recently, hydrogels have gained enormous interest in three-dimensional (3D) bioprinting toward developing functional substitutes for tissue remolding. However, it is highly challenging to transmit electrical signals to cells due to the limited electrical conductivity of the bioprinted hydrogels. Herein, we demonstrate the 3D bioprinting-assisted fabrication of a conductive hydrogel scaffold based on poly-3,4-ethylene dioxythiophene (PEDOT) nanoparticles (NPs) deposited in gelatin methacryloyl (GelMA) for enhanced myogenic differentiation of mouse myoblasts (C2C12 cells). Initially, PEDOT NPs are dispersed in the hydrogel uniformly to enhance the conductive property of the hydrogel scaffold. Notably, the incorporated PEDOT NPs showed minimal influence on the printing ability of GelMA. Then, C2C12 cells are successfully encapsulated within GelMA/PEDOT conductive hydrogels using 3D extrusion bioprinting. Furthermore, the proliferation, migration and differentiation efficacies of C2C12 cells in the highly conductive GelMA/PEDOT composite scaffolds are demonstrated using various in vitro investigations of live/dead staining, F-actin staining, desmin and myogenin immunofluorescence staining. Finally, the effects of electrical signals on the stimulation of the scaffolds are investigated toward the myogenic differentiation of C2C12 cells and the formation of myotubes in vitro. Collectively, our findings demonstrate that the fabrication of the conductive hydrogels provides a feasible approach for the encapsulation of cells and the regeneration of the muscle tissue.

Self-propelling micro-/nano-motors: Mechanisms, applications, and challenges in drug delivery.

In recent times, numerous efforts have been put forward to fabricating the self-propelling micro-/nano-motors (MNMs) for various applications, such as drug delivery, environmental remediation, biosensing, and precision surgery at the micro-/nanoscale, among others. Owing to their potential advantages, the application of such innovative architectures has been increasingly recognized towards addressing various challenges in the related fields. Specifically, these MNMs offer enormous potential in nanomedicine in overcoming the significant challenge of low permeation of the biological barriers. Herein, we emphasize the powered mechanism of MNMs, including artificial and natural-based MNMs, and discuss the characteristics, as well as the challenges being faced by MNMs in drug delivery. Further, the research progress of MNMs as drug carriers in different environments (gastrointestinal tract, saliva, urinary bladder, blood, and extracellular matrix, ECM) of the body in recent years is summarized, highlighting the representative works on MNMs towards in vivo applications. Together, we firmly believe that these innovative MNMs-based designs may play a crucial role in the clinical practice in the future.

Synergistic antitumor efficacy of doxorubicin and gambogic acid-encapsulated albumin nanocomposites.

Despite the success, the applicability of traditional chemotherapy still faces several challenges in treating cancer-related ailments, such as enormous toxicity and adverse effects. Combinatorial chemotherapy at reduced doses can offer augmented therapeutic efficiency through multiple mechanisms and even substantially circumvents the issues of toxicity and adverse effects. To demonstrate these facts, herein, two kinds of antitumor drugs, doxorubicin (DOX) and gambogic acid (GA), are encapsulated in bovine serum albumin (BSA) nanoparticles distinctly, resulting in DNP and GNP, respectively. These drug-loaded albumin nanocomposites, DNPs, and GNPs, showed a synergistic effect in ablating HepG2 tumor cells at a combination index (CI) of 0.38. Further, the ex vivo fluorescence imaging investigation confirmed the enriched drug internalization in the tumor precisely, which could be due to the enhanced permeation and retention (EPR) effect, resulting in the augmented therapeutic efficiency of designed nanoformulation. Notably, the synergistic tumor inhibition efficacy is more significantly attained at a 3-fold lesser dose of combined treatment than that of single full dose treatment in vivo. As anticipated, these conditions resulted in reduced organ toxicity. Together, this combinatorial strategy using BSA-based composites is an appropriate approach for application in medicine.

Uniform field electrospinning for 3D printing of fibrous configurations as strain sensors.

Electrospinning is becoming an efficient method to produce fibers in the submicron range, but the bending instability of conventional electrospinning system (CES) brings limitations in the distinctive deposition of electrospun fibers. Herein, we proposed a strategy to update the electrospinning system through establishment of a uniform electric field, realizing 3D printing of electrospun fibers with well-controlled, low-cost, and template-free manners. The uniform field electrospinning (UFES) apparatus is configured by inserting the electrospinning nozzle into the center of an aided metal plate. The electric field simulation of UFES indicates a uniform distribution between the aided metal plate and the collector, while a diverging and weaker electric field is produced by CES. The collector of UFES is mounted on a translation stage, which moves along x and y axes under computer control. The distinctive deposition of electrospun fibers produces fibrous mats with rectangular patterns of different grid sizes, and butterfly and TaiJi figures with high resolutions are directly written by UFES. The layer-by-layer deposition of electrospun fibers under UFES produces microscale Mongolian yurts with distinct hollow structure. Fibrous blocks with an average width of 120 µm and height of 630 µm were printed by UFES from conductive polymer composites and constructed into strain sensors. The electric current strength of fibrous microblocks changes sharply in response to the finger bending and release, indicating the capability to monitor human motions. Thus, this study demonstrates that the UFES becomes an easy-handling strategy for 3D printing of electrospun fibers to create complex geometries.

Sequential Drug Release to Modulate Collagen Synthesis and Promote Micelle Penetration in Tumors.

Cancer chemotherapy is confronted with insufficient drug penetration in tumors. "Solid tumor priming" is proposed to modulate the abnormal tumor microenvironment but suffers from limited digestion efficiency and underlying tumor metastasis. Losartan (Los) and telmisartan (Tel) are well-known antihypertensive agents and show capabilities in inhibiting collagen synthesis by cancer-associated fibroblasts. Up to now, no attempt has been made to achieve a local and sustained release of Los and Tel in tumors while alleviating the side effects after systemic administration. In the previous study, micelles were loaded into fiber fragments to achieve high drug accumulation in tumors after intratumoral administration. In the current study, Los and Tel are blend electrospun into fibers to retard the collagen synthesis and promote the tissue penetration of micelles released from fiber fragments. The loading of Los and Tel shows no effect on the micelle release, cellular uptake, and cytotoxicities of micelles released from fiber fragments. Because of the hydrophilicity, Los is almost released out after 5 day in pH 6.8 buffers, while hydrophobic Tel is gradually released for 30 days. Thus, fiber fragments with loaded Los and Tel are combined to achieve a sustained remodeling of collagen levels in tumors, and the combination with a ratio of 1/2 showed the most significant and consistent reductions of collagen I levels in tumors, as determined via Western blotting, Masson's trichrome, and immunofluorescence staining. A wide distribution of micelles is observed in the tumor tissues, as well as strong fluorescence in the distal sections of tumors during 14 days. Compared with pristine fiber fragments, the sequential release of Los and Tel induces stronger inhibition of tumor growth, lower expression of hypoxia-inducible factor-α (HIF-α), and fewer tumor metastases to lungs. Thus, this study demonstrates a feasible strategy to enhance the local retention and even distribution of chemotherapeutic agents in tumors in favor of therapeutic efficacy.

Synergistic antitumor efficacy of hybrid micelles with mitochondrial targeting and stimuli-responsive drug release behavior.

The term synergism means that the overall therapeutic benefits should be greater than the sum of the effects of individual agents and that the optimal therapeutic efficacy can be achieved at reduced doses. Micellar systems usually fail to deliver multiple drugs to target sites at synergistic doses and thus are not able to maximize the antitumor efficacy. In the current study, we demonstrate a strategy to coordinate the release of camptothecin (CPT) and α-tocopheryl succinate (TOS) from hybrid micelles for nucleus and mitochondrion interferences. TOS is decorated with cationic triphenylphosphonium (TPP) to promote the targeting capability of TOS-TPP to mitochondria. The combination of CPT and TOS-TPP shows strong synergistism with a combination index of 0.186. Hyaluronic acid (HA) is conjugated with CPT or TOS-TPP via disulfide linkages for tumor cell targeting and intracellular reduction-triggered release. Both conjugates either separately self-assemble into MC and MT micelles, or are blended at different ratios to form MC-T hybrid micelles. In response to elevated intracellular glutathione levels, the coordinated release of CPT and TOS-TPP from MC-T results in a combination index of 0.26 and the dose-reduction indexes of CPT and TOS are 7.7 and 3.4, respectively. Compared with MC and MT, MC-T micelles with 5 fold lower doses exhibit higher intracellular reactive oxygen species (ROS) levels, comparable tumor growth inhibition and animal survival, indicating no hematologic and intestinal toxicities. Moreover, the HA conjugates of MC-T are linked to polylactide via acid-labile linkages and electrospun into short fibers (MC-T@SF) as an injectable depot to release MC-T in response to the acidic tumor microenvironment. At a predetermined synergistic ratio, MC-T@SF with 5 fold lower doses achieves antitumor profiles comparable to those of individual micelle-loaded short fibers. Therefore, the hybrid micelles and micelle-releasing short fibers represent a feasible strategy to synergistically enhance the therapeutic efficacy and enable significant reduction in effective doses of chemotherapeutic agents.

Bacterial microbots for acid-labile release of hybrid micelles to promote the synergistic antitumor efficacy.

Bacteria have inherent properties of self-propelled navigation and specific infiltration into solid tumors. In the current study, we investigate a novel type of bacterial microbots for delivery of hybrid micelles to promote the synergistic antitumor efficacy. Escherichia coli Nissle 1917 (EcN) is used as a bacterial carrier to immobilize amphiphilic copolymers through acid-labile 2-propionic-3-methylmaleic anhydride (CDM) linkers. Doxorubicin (DOX) and α-tocopheryl succinate (TOS) are conjugated with poly(ethylene glycol) through disulfide linkers to obtain amphiphilic promicelle polymers (PMTOS and PMDOX). Tetrazine and norbornene terminals are grafted on EcN and PMTOS/PMDOX copolymers, respectively, and the mild and site-specific bioorthogonal reaction between them maintains the viability, motion ability, and tumor accumulation capability of the conjugated EcN. The PMTOS/PMDOX copolymers are released from bacterial microbots in response to the slightly acidic tumor microenvironment, followed by in situ formation of these copolymers as hybrid micelles (MD/T). The self-assembled micelles from PMTOS/PMDOX with a ratio of 1:2 demonstrate the most significant synergistic efficacy, and the released MD/T hybrid micelles exhibit cellular uptake efficiency, glutathione (GSH)-sensitive drug release, and cytotoxicities similar to those exhibited by micelles prepared by solvent evaporation. Because of the consecutive process of the self-propelling nature of bacteria and preferential accumulation of EcN in tumors, in situ formation of MD/T hybrid micelles, and intracellular drug release, bacterial microbots have shown remarkable antitumor efficacy with regard to animal survival, tumor growth, and apoptosis induction in tumor cells. Therefore, we demonstrate a feasible strategy for the construction of bacterial microbots to achieve tumor accumulation and on-demand release of multiple therapeutic agents for synergistic antitumor efficacy. STATEMENT OF SIGNIFICANCE: Challenges remain in the targeted delivery of nanoparticles to solid tumors and the realization of synergistic efficacy in cancer chemotherapy. In the current study, we explore a novel class of bacterial microbots to load, deliver, and release hybrid micelles. Escherichia coli Nissle 1917 (EcN) is used as a bacterial carrier to immobilize amphiphilic copolymers through acid-labile linkers, and the released copolymers are self-assembled into micelles. The resulting bacterial microbots integrate self-propelling bacteria and self-assembling amphiphilic polymers into micelles and realize pH-responsive release of promicelle polymers from bacterial microbots and glutathione-responsive intracellular release of drugs. A synergistic antitumor efficacy is achieved using hybrid micelles, which release both doxorubicin and α-tocopheryl succinate to display toxicities in the nucleus and mitochondria, respectively.

Acid-Labile Degradation of Injectable Fiber Fragments to Release Bioreducible Micelles for Targeted Cancer Therapy.

Cancer chemotherapy is confronted with difficulties enhancing the tumor accumulation, improving the bioavailability, and relieving the adverse effect of chemotherapeutic agents. To address the challenges, this study proposes a feasible strategy to realize a sustained release of drug-loaded micelles from fiber fragments after intratumoral injection. Camptothecin (CPT) is grafted on hyaluronic acid (HA) via 3,3'-dithiodipropionic acid to obtain reduction-sensitive promicelle polymers (PMCPT), which are conjugated with poly(d,l-lactide) via 2-propionic-3-methylmaleic anhydride (CDM) to obtain acid-labile copolymers for the preparation of injectable fiber fragments. Fiber fragments show remarkable acid-sensitive degradation, and the released PMCPT are spontaneously self-assembled into micelles, followed by subsequent HA-mediated internalization into tumor cells and reduction-sensitive release of drugs in the cytosol. Compared to fresh micelles prepared by ultrasonication, the micelles released via the degradation of fiber fragments display similar behaviors, such as the size and morphology, glutathione-sensitive drug release, cellular uptake efficiency, and cytotoxicity. Taking advantage of the aggregation-induced emission (AIE) effect of tetraphenylethene (TPE), the micelle release, cellular uptake, and tumor accumulation have been elucidated from the self-assembly induced fluorescence light-up in vitro and after intratumoral injection. Compared to the intratumoral injection of free micelles, sustained micelle release from fiber fragments resulted in significantly higher antitumor efficacy with respect to the inhibition of tumor growths, prolonging of animal survivals, and induction of cell apoptosis in tumor tissues. Thus, the micelle-releasing fiber fragments integrated with double targeting capabilities and double stimuli responsiveness have demonstrated a superior capacity to sustainably deliver chemotherapeutic agents directly within tumor cells.

An implantable depot capable of in situ generation of micelles to achieve controlled and targeted tumor chemotherapy.

Camptothecin (CPT)-containing promicelle polymers (PMCPT) based on 4-armed poly(ethylene glycol) (PEG) were developed previously to self-assemble into folate-targeted and glutathione (GSH)-sensitive micelles (MCPT). To address severe systemic toxicity and lack of tumor specificity implicated in the intravenous administration of MCPT, a micelle-generating depot has been developed by blend electrospinning of PEG-poly(lactide) (PELA) copolymers, PMCPT and polyethylene oxide (PEO). Upon implantation of the depot onto a tumor, PMCPT are sustainably released to self-assemble into MCPT on the tumor site. The release of PMCPT is adjusted by varying PEO/PELA ratios and reaches in the range of 23-92% after 30 days of incubation. By making use of the aggregation-induced emission (AIE) features of tetraphenylethylene (TPE) derivatives, the release process of TPE-containing promicelle polymers (PMTPE) from the depot and the spontaneous formation of micelles (MTPE) have been monitored from the self-assembly-induced fluorescence light-up both in vitro and in vivo. Compared with intravenous injection of MCPT, the micelle-generating depot has significantly enhanced micelle accumulation in the tumor for an extended period of time and resulted in stronger tumor inhibitory efficacy, reduced systemic toxicity and more effective inhibition of tumor metastasis, demonstrating great potential for targeted cancer therapy with sustained efficacy. STATEMENT OF SIGNIFICANCE: The promicelle polymer-co-electrospun fibers are developed to form a micelle-generating depot after implantation onto the tumor. The promicelle polymers are continuously released and simultaneously self-assemble into folate-targeted and glutathione-sensitive micelles, ensuring sustained micelle delivery for more than 30 days. The process of micelle formation in the tumor tissue is visualized in vivo for the first time based on the mechanism of aggregation-induced emission. This in situ micelle formation also prevents premature drug release and rapid clearance from the bloodstream. In addition, these fibers deliver anti-cancer agents directly within tumor cells via dual selectivity (i.e. spatially selective accumulation in tumor tissues via implantation and selective internalization into tumor cells via folate receptor-mediated endocytosis) and on-demand drug release in response to cytosol GSH. They exhibit superior tumor inhibitory efficacy with minimal systemic toxicity, and prevent from malignant metastasis of cancer cells.

Tumor pH-Responsive Release of Drug-Conjugated Micelles from Fiber Fragments for Intratumoral Chemotherapy.

The tumor accumulation of micelles is essential to enhance the cellular uptake and extend the release of chemotherapeutic agents. In the previous study camptothecin (CPT)-conjugated micelles (MCPT) were constructed with disulfide linkages and folate moieties for reduction-sensitive release and cell-selective uptake. This study proposes a strategy to integrate the promicelle polymers (PMCPT) into fiber fragments for intratumoral injection, realizing acid-liable release of PMCPT in response to acidic tumor microenvironment and spontaneous self-assembly into MCPT. Acid-liable 2-propionic-3-methylmaleic anhydride (CDM)-linked poly(ethylene glycol) initiates the ring-opening polymerization of dl-lactide as the fiber matrix. There is no apparent burst release of MCPT from fiber fragments and around 80% of accumulated releases after incubation in pH 6.5 buffers for 40 days. Compared to MCPT freshly prepared via solvent evaporation, the micelles released from fiber fragments reveal similar profiles, such as folate-mediated cellular uptake and glutathione-sensitive drug release. Taking advantage of the aggregation-induced emission (AIE) effect of tetraphenylethylene (TPE) derivatives, TPE-conjugated micelles (MTPE) have been successfully been used to track the self-assembly into micelles after release from fibers and subsequent cell internalization into cytosol. The self-assembly induced fluorescence light-up was also detected after intratumoral injection of fiber fragments. Compared with CPT-loaded fiber fragments and intratumoral or intravenous injection of free MCPT, the sustained release from fiber fragments and high accumulation of micelles in tumors result in significantly higher inhibition of tumor growths, prolongation of animal survival, and induction of tumor cell apoptosis. Thus, the integration of double targeting and double stimuli responsiveness into fragmented fibers provides a feasible strategy to realize the sustained micelle release from fibers and promote the therapeutic efficacy.

Fluorescent Strips of Electrospun Fibers for Ratiometric Sensing of Serum Heparin and Urine Trypsin.

"Turn-on" or "turn-off" probes remain challenges in the establishment of sensitive, easily operated, and reliable methods for in situ monitoring bioactive substances. In the current study, electrospun fibrous strips are designed to provide straightforward observations of ratiometric color changes with the naked eye in the presence of serum heparin or urine trypsin. A tetraphenylethene (TPE) derivative is constructed and along with phloxine B is grafted on fibers, followed by protamine adsorption to induce static quenching of phloxine B and aggregation-induced emission of the TPE derivative. The presence of heparin or trypsin removes protamine to restore the fluorescence of phloxine B at 574 nm (I574) and relieve the emission of the TPE derivative at 472 nm (I472). The grafting densities of phloxine B and the TPE derivative are essential to achieve the optimal fluorescence-intensity ratio of I574/I472 for the ratiometric detection of heparin and trypsin. Under illumination by an ultraviolet lamp, the fibrous mats turn from cyan to green in the presence of heparin at 0.4 U/mL and to a bright yellow at 0.8 U/mL, which is feasible in sensing serum heparin levels during postoperative and long-term care of patients after cardiovascular surgery. The protamine digestion results in similar color transitions with increasing trypsin levels up to 8 µg/mL, indicating the potential for monitoring urine trypsin levels of pancreas transplant patients. The color strips based on the ratiometric fluorescent response indicate advantages in lowering the detection limit and improving the accuracy and reproducibility, bearing great potential for a real-time and naked-eye detection of bioactive substances as self-test devices.

Synergistic antitumor efficacy of redox and pH dually responsive micelleplexes for co-delivery of camptothecin and genes.

Challenges remain to load and deliver two or multiple drugs of complementary effects for synergistic cancer therapies. In the current study, multiarmed amphiphilic copolymers of 4-arm poly(ethylene glycol) (PEG) and polyaspartate (PAsp) are created for conjugation of camptothecin (CPT) and condensation with tumor necrosis factor-α (TNF) plasmids. Diethylenetriamine (DET) is grafted on PAsp, and CPT is conjugated onto PAsp(DET) by disulfide linkages to form hydrophobic cores of micelles, followed by condensation with TNF plasmids to form micelleplexes. The cis-aconitic linkers are introduced between PEG and PAsp(DET) to remove PEG shells in response to acidic pH, resulting in destabilized micelleplexes and prompted endosomal escape into the cytosol. The micelleplex disintegration in response to reductive stimuli in the cytosol leads to an efficient CPT release and pDNA disassociation. The co-delivery of CPT with TNF plasmids enhances the gene transfection of micelleplexes at low N/P ratios, and shows synergetic cytotoxicities to tumor cells with 2.5 and 8 folds lower IC50s compared with those after treatment with CPT or TNF alone, respectively. The micelleplex treatment on 4T1 tumor models dramatically extends the animal survival and suppresses the tumor growth with 2.3 and 3 folds lower in volume compared with CPT or TNF treatment alone, respectively. Histological and biochemical analyses display TNF expressions in tumor tissues after micelleplex treatment, resulting in significantly larger necrotic regions in tumors, higher cell apoptosis rates, and no obvious sign of tumor metastasis in lungs compared with other treatment. Therefore, the multifunctional micelleplexes based on multiarmed PEG-PAsp(DET) copolymers offer the targeted drug/gene delivery, dually responsive drug/gene release and synergistic antitumor efficacy, holding great promises for combination therapies. STATEMENT OF SIGNIFICANCE: Micelleplexes are constructed from multiarmed amphiphilic copolymers with conjugation of captothecin (CPT) and condensation of tumor necrosis factor-α (TNF) plasmid. The pH/redox stimuli realize co-delivery of CPT and pDNA in a sequential manner of folate-mediated endocytosis, endosomal escape induced by PEG cleavage, reduction-sensitive release of CPT in cytosol, and pDNA release from disintegrated polyplexes after CPT release. Compared with CPT or TNF treatment alone, the micelleplexes achieve 2.5 and 8 folds higher cytotoxicities to tumor cells, and suppress the tumor growth with 2.3 and 3 folds lower in volume, respectively. It demonstrates a feasible strategy to develop multifunctional micelleplexes with simultaneous drug conjugation and pDNA condensation, dually responsive drug/gene release and synergistic antitumor efficacy, holding great promise for combinational therapies.

Tunable conjugation densities of camptothecin on hyaluronic acid for tumor targeting and reduction-triggered release.

UNLABELLED: Micelles self-assembled from drug-conjugated polymers indicate advantages in alleviating the premature release before reaching the intended site. Hyaluronic acid (HA) is known to specifically bind with a transmembrane glycoprotein CD44, overexpressed in many types of cancerous cells, and can also be served as micelle carriers. However, an excess amount of drug conjugation to HA backbone may be detrimental to the receptor-mediated cellular uptake. Up to now, the effect of conjugation densities of drugs has never been determined on the physical properties and biological performance of resulting micelles. In the current study, camptothecin (CPT) was conjugated on HA through 3,3'-dithiodipropionic acid to self-assemble into reduction-sensitive micelles. The substitution degrees of CPT on HA backbone were tuned from around 4-20%, to clarify the effects on the cellular uptake efficiency and cytotoxicities of micelles, as well as the tumor accumulation and antitumor efficacy. The CPT substitution degree of around 15% on HA resulted in micelles with a higher cytotoxicity to 4T1 cells and achieved a better balance between the cellular uptake and reduction-triggered drug release, compared with other micelles. In contrast to a fast kidney clearance and an even distribution in major organs after intravenous injection of free CPT, the optimized micelles were accumulated in tumors, livers and lungs. The micelle content indicated a significant decrease in livers after 24h, while that in tumors displayed a significant increase to 4.9% of the injection dose. The tumor accumulation of micelles led to strong tumor suppression with minimal systemic toxicity. The in situ tumor inhibition and the accumulation of micelles in liver and lungs inhibited tumor metastasis to these tissues. It demonstrates a feasible strategy to develop drug-HA conjugate micelles with a concise and tunable structure for tumor targeting and reduction-triggered release. STATEMENT OF SIGNIFICANCE: Hyaluronic acid (HA) can be served as micelle carriers and targeting ligands to tumor cells. However, the effects of drug conjugation densities on the physical profile and biological performance of resulting micelles have never been investigated. In the current study, camptothecin is conjugated on HA with reduction-sensitive linkers, and the substitution degrees of camptothecin on HA backbone vary from around 4-20%. The micelles with a substitution degree of around 15% achieve a better balance between the cellular uptake and reduction-triggered drug release and a higher cytotoxicity than others. It demonstrates a feasible strategy to develop drug-HA conjugate micelles with a concise and tunable structure for tumor targeting and reduction-triggered release.