Beyond nanoparticle-based oral drug delivery: transporter-mediated absorption and disease targeting

Various strategies at the microscale/nanoscale have been developed to improve oral absorption of therapeutics. Among them, gastrointestinal (GI)-transporter/receptor-mediated nanosized drug delivery systems (NDDSs) have drawn attention due to their many benefits, such as improved water solubility, improved chemical/physical stability, improved oral absorption, and improved targetability of their payloads. Their therapeutic potential in disease animal models (e.g., solid tumors, virus-infected lungs, metastasis, diabetes, and so on) has been investigated, and could be expanded to disease targeting after systemic/lymphatic circulation, although the detailed paths and mechanisms of endocytosis, endosomal escape, intracellular trafficking, and exocytosis through the epithelial cell lining in the GI tract are still unclear. Thus, this review summarizes and discusses potential GI transporters/receptors, their absorption and distribution, in vivo studies, and potential sequential targeting (e.g., oral absorption and disease targeting in organs/tissues).

Bioreducible exosomes encapsulating glycolysis inhibitors potentiate mitochondria-targeted sonodynamic cancer therapy via cancer-targeted drug release and cellular energy depletion

Nanocarrier-assisted sonodynamic therapy (SDT) has shown great potential for the effective and targeted treatment of deep-seated tumors by overcoming the critical limitations of sonosensitizers. However, in vivo SDT using nanocarriers is still constrained by their intrinsic toxicity and nonspecific cargo release. In this study, we developed bioreducible exosomes for the safe and tumor-specific delivery of mitochondria-targeting sonosensitizers [triphenylphosphonium-conjugated chlorin e6 (T-Ce6)] and glycolysis inhibitors (FX11). Redox-cleavable diselenide linker-bearing lipids were embedded into exosomes to trigger drug release in response to overexpressed glutathione in the tumor microenvironment. Bioreducible exosomes facilitate the cytoplasmic release of their payload in the reducing environment of tumor cells. They significantly enhance drug release and sonodynamic effects when irradiated with ultrasound (US). The mitochondria-targeted accumulation of T-Ce6 efficiently damaged the mitochondria of the cells under US irradiation, accelerating apoptotic cell death. FX11 substantially inhibited cellular energy metabolism, potentiating the antitumor efficacy of mitochondria-targeted SDT. Bioreducible exosomes effectively suppressed tumor growth in mice without significant systemic toxicity, via a combination of mitochondria-targeted SDT and energy metabolism-targeted therapy. This study offers new insights into the use of dual stimuli-responsive exosomes encapsulating sonosensitizers for safe and targeted sonodynamic cancer therapy.

Brain endothelial cell-derived extracellular vesicles with a mitochondria-targeting photosensitizer effectively treat glioblastoma by hijacking the blood‒brain barrier

Glioblastoma (GBM) is the most aggressive malignant brain tumor and has a high mortality rate. Photodynamic therapy (PDT) has emerged as a promising approach for the treatment of malignant brain tumors. However, the use of PDT for the treatment of GBM has been limited by its low blood‒brain barrier (BBB) permeability and lack of cancer-targeting ability. Herein, brain endothelial cell-derived extracellular vesicles (bEVs) were used as a biocompatible nanoplatform to transport photosensitizers into brain tumors across the BBB. To enhance PDT efficacy, the photosensitizer chlorin e6 (Ce6) was linked to mitochondria-targeting triphenylphosphonium (TPP) and entrapped into bEVs. TPP-conjugated Ce6 (TPP-Ce6) selectively accumulated in the mitochondria, which rendered brain tumor cells more susceptible to reactive oxygen species-induced apoptosis under light irradiation. Moreover, the encapsulation of TPP-Ce6 into bEVs markedly improved the aqueous stability and cellular internalization of TPP-Ce6, leading to significantly enhanced PDT efficacy in U87MG GBM cells. An in vivo biodistribution study using orthotopic GBM-xenografted mice showed that bEVs containing TPP-Ce6 [bEV(TPP-Ce6)] substantially accumulated in brain tumors after BBB penetration via transferrin receptor-mediated transcytosis. As such, bEV(TPP-Ce6)-mediated PDT considerably inhibited the growth of GBM without causing adverse systemic toxicity, suggesting that mitochondria are an effective target for photodynamic GBM therapy.

Piezocatalytic 2D WS2 Nanosheets for Ultrasound-Triggered and Mitochondria-Targeted Piezodynamic Cancer Therapy Synergized with Energy Metabolism-Targeted Chemotherapy

Piezoelectric nanomaterials that can generate reactive oxygen species (ROS) by piezoelectric polarization under an external mechanical force have emerged as an effective platform for cancer therapy. In this study, piezoelectric 2D WS₂ nanosheets are functionalized with mitochondria-targeting triphenylphosphonium (TPP) for ultrasound (US)-triggered, mitochondria-targeted piezodynamic cancer therapy. In addition, a glycolysis inhibitor (FX11) that can inhibit cellular energy metabolism is loaded into TPP- and poly(ethylene glycol) (PEG)-conjugated WS₂ nanosheet (TPEG-WS₂ ) to potentiate its therapeutic efficacy. Upon US irradiation, the sono-excited electrons and holes generated in the WS₂ are efficiently separated by piezoelectric polarization, which subsequently promotes the production of ROS. FX11-loaded TPEG-WS₂ (FX11@TPEG-WS₂ ) selectively accumulates in the mitochondria of human breast cancer cells. In addition, FX11@TPEG-WS₂ effectively inhibits the production of adenosine triphosphate . Thus, FX11@TPEG-WS₂ exhibits outstanding anticancer effects under US irradiation. An in vivo study using tumor-xenograft mice demonstrates that FX11@TPEG-WS₂ effectively accumulated in the tumors. Its tumor accumulation is visualized using in vivo computed tomography . Notably, FX11@TPEG-WS₂ with US irradiation remarkably suppresses the tumor growth of mice without systemic toxicity. This study demonstrates that the combination of piezodynamic therapy and energy metabolism-targeted chemotherapy using mitochondria-targeting 2D WS₂ is a novel strategy for the selective and effective treatment of tumors.

Mitochondria-targeting sonosensitizer-loaded extracellular vesicles for chemo-sonodynamic therapy

Sonodynamic therapy (SDT) has emerged as an effective therapeutic modality as it employs ultrasound (US) to eradicate deep-seated tumors noninvasively. However, the therapeutic efficacy of SDT in clinical settings remains limited owing to the low aqueous stability and poor pharmacokinetic properties of sonosensitizers. In this study, extracellular vesicles (EVs), which have low systemic toxicity, were used as clinically available nanocarriers to effectively transfer a sonosensitizer to cancer cells. Chlorin e6 (Ce6), a sonosensitizer, was conjugated to a mitochondria-targeting triphenylphosphonium (TPP) moiety and loaded into EVs to enhance the efficacy of SDT, because mitochondria are critical subcellular organelles that regulate cell survival and death. Additionally, piperlongumine (PL), a pro-oxidant and cancer-specific chemotherapeutic agent, was co-encapsulated into EVs to achieve efficient and selective anticancer activity. The EVs substantially amplified the cellular internalization of TPP-conjugated Ce6 (TPP-Ce6), resulting in the enhanced generation of intracellular reactive oxygen species (ROS) in MCF-7 human breast cancer cells upon US exposure. Importantly, EVs encapsulating TPP-Ce6 effectively destroyed the mitochondria under irradiation with US, leading to efficient anticancer activity. The co-encapsulation of pro-oxidant PL into EVs significantly enhanced the SDT efficacy in MCF-7 cells through the excessive generation of ROS. Moreover, the EV co-encapsulating TPP-Ce6 and PL [EV(TPP-Ce6/PL)] exhibited cancer-specific cell death owing to the cancer-selective apoptosis triggered by PL. In vivo study using MCF-7 tumor-xenograft mice revealed that EV(TPP-Ce6/PL) effectively accumulated in tumors after intravenous injection. Notably, treatment with EV(TPP-Ce6/PL) and US inhibited tumor growth significantly without causing systemic toxicity. This study demonstrated the feasibility of using EV(TPP-Ce6/PL) for biocompatible and cancer-specific chemo-SDT.

Extracellular vesicles with high dual drug loading for safe and efficient combination chemo-phototherapy

Extracellular vesicles (EVs) have emerged as biocompatible nanocarriers for efficient delivery of various therapeutic agents, with intrinsic long-term blood circulatory capability and low immunogenicity. Here, indocyanine green (ICG)- and paclitaxel (PTX)-loaded EVs [EV(ICG/PTX)] were developed as a biocompatible nanoplatform for safe and efficient cancer treatment through near-infrared (NIR) light-triggered combination chemo/photothermal/photodynamic therapy. High dual drug encapsulation in EVs was achieved for both the hydrophilic ICG and hydrophobic PTX by simple incubation. The EVs substantially improved the photostability and cellular internalization of ICG, thereby augmenting the photothermal effects and reactive oxygen species production in breast cancer cells upon NIR light irradiation. Hence, ICG-loaded EVs activated by NIR light irradiation showed greater cytotoxic effects than free ICG. EV(ICG/PTX) showed the highest anticancer activity owing to the simultaneous chemo/photothermal/photodynamic therapy when compared with EV(ICG) and free ICG. In vivo study revealed that EV(ICG/PTX) had higher accumulation in tumors and improved pharmacokinetics compared to free ICG and PTX. In addition, a single intravenous administration of EV(ICG/PTX) exhibited a considerable inhibition of tumor proliferation with negligible systemic toxicity. Thus, this study demonstrates the potential of EV(ICG/PTX) for clinical translation of combination chemo-phototherapy.

Engineered extracellular vesicle-based sonotheranostics for dual stimuli-sensitive drug release and photoacoustic imaging-guided chemo-sonodynamic cancer therapy

Sonodynamic therapy has shown promise as an effective alternative to conventional photodynamic therapy owing to its ability to treat deep-seated tumors. However, the development of stimuli-responsive sonosensitizers with high biocompatibility faces a significant challenge.

Methods: In this study, we developed dual stimuli-responsive sonosensitizers with desirable biosafety using extracellular vesicles (EVs), a class of naturally occurring nanoparticles. Indocyanine green (ICG), which functions as both a sonosensitizer and photoacoustic (PA) imaging agent, was loaded into EVs, together with paclitaxel (PTX) and sodium bicarbonate (SBC), to achieve pH-responsive PA imaging-guided chemo-sonodynamic combination therapy.

Results: The EVs significantly improved the cellular uptake of ICG, thus triggering enhanced sonodynamic effects in breast cancer cells. SBC-, ICG-, and PTX-loaded EV [SBC-EV(ICG/PTX)] efficiently released the PTX in response to acidic pH in the endo/lysosomes because CO₂ bubbles generated from the SBC caused the EV membranes to burst. The drug release was further facilitated by ultrasound (US) treatment, demonstrating dual pH/US-responsive drug release. The ICG- and PTX-loaded EVs exhibited efficient anticancer activity against breast tumor cells owing to the combination of chemo-sonodynamic therapy. High-resolution PA imaging visualized the preferential tumor accumulation of SBC-EV(ICG/PTX) in tumor-bearing mice. Notably, a single intravenous injection of SBC-EV(ICG/PTX) with US irradiation significantly suppressed tumor growth in mice without systemic toxicity.

Conclusions: Our findings demonstrate that dual stimuli-responsive SBC-EV(ICG/PTX) are promising sonotheranostic nanoplatforms for safe and efficient chemo-sonodynamic combination cancer therapy and photoacoustic imaging.

Beyond hydrophilic polymers in amphiphilic polymer-based self-assembled NanoCarriers: Small hydrophilic carboxylate-capped disulfide drug delivery system and its multifunctionality and multispatial targetability

Due to increasing safety and intracellular delivery concerns about hydrophilic polymers in amphiphilic polymer-based nanoparticles (NPs), this study investigates small hydrophilic molecule-stabilized NPs for effective intracellular delivery with multiorganelle targetability and dual responsiveness to acidic pH/glutathione (GSH). In the construction of small hydrophilic molecule-stabilized NP (MSPCL-NP), the A-B-A-type amphiphilic polymer (MSPCL-P) is composed of two short hydrophilic carboxylate-capped disulfide derivatives (A) that replace hydrophilic polymers and assist in providing colloidal stability and preventing antibody (e.g., at least anti-PEG antibody)-mediated specific interactions and complement activation in the plasma and a hydrophobic multiple disulfide-containing poly(ε-caprolactone) block (B) that carries hydrophobic drugs. The carboxylates on the surface of MSPCL-NP target the acidic extratumoral/endolysosomal milieu by sensing and buffering acidic pH values, and the hydrophobic carboxylic acids improve adsorptive endocytosis and effective endosomal escape. Multiple disulfide linkages selectively target cytosolic GSH, resulting in rapid drug release from the destroyed MSPCL-NP via the cleavage of disulfide bonds in MSPCL-P. Doxorubicin (DOX)-loaded NP (DOX@MSPCL-NP) exerts strong effects on killing cells in vitro and inhibits tumor growth in HCT116 xenograft tumor-bearing mice. In conclusion, the multifunctionality and multispatial targetability of MSPCL-NP might effectively overcome various sequential drug delivery hurdles, ranging from blood circulation to drug release. Furthermore, the introduction of small hydrophilic molecules represents a potential strategy to make self-assembled NPs without the use of hydrophilic polymers.

Pro-oxidant drug-loaded porphyrinic zirconium metal-organic-frameworks for cancer-specific sonodynamic therapy

Sonodynamic therapy, which utilizes ultrasound (US) to produce cytotoxic reactive oxygen species (ROS), can overcome the critical drawbacks of photodynamic therapy, such as limited tissue penetration depth. However, the development of sonosensitizers having superior sonodynamic effects and desirable biocompatibility remains a major challenge. In this study, nanoscale zirconium-based porphyrinic metal organic frameworks (MOFs) (PCN-222) were developed as safe and effective nanosonosensitizers. Polyethylene glycol (PEG)-coated PCN-222 (PEG-PCN) was loaded with a pro-oxidant drug, piperlongumine (PL), to enable tumor-specific chemo-photodynamic combination therapy. Both PEG-PCN and PL-incorporated PEG-PCN (PL-PEG-PCN) showed high colloidal stability in biological media. In addition, nanoscale PL-PEG-PCN was efficiently internalized by breast cancer cells, leading to substantially increased ROS generation under US exposure. The effective intracellular delivery of PL by PEG-PCN further elevated the level of intracellular ROS in breast cancer cells owing to the pro-oxidative activity of PL. Therefore, PL-PEG-PCN revealed significantly higher sonotoxicity than free PL and PEG-PCN. Owing to the cancer-specific apoptosis triggered by PL, PL-PEG-PCN showed cancer-selective cell death in breast cancer cells compared with normal fibroblast cells. This study demonstrates that pro-oxidant drug-loaded porphyrinic MOFs are biocompatible and effective sonosensitizers for cancer-targeted chemo-sonodynamic combination therapy.

Metformin and Dichloroacetate Suppress Proliferation of Liver Cancer Cells by Inhibiting mTOR Complex 1

The Warburg effect is important for cancer cell proliferation. This phenomenon can be flexible by interaction between glycolysis and mitochondrial oxidation for energy production. We aimed to investigate the anticancer effects of the pyruvate dehydrogenase kinase inhibitor, dichloroacetate (DCA) and the mitochondrial respiratory complex I inhibitor metformin in liver cancer cells. The anticancer effect of DCA and/or metformin on HepG2, PLC/PRF5 human liver cancer cell lines, MH-134 murine hepatoma cell lines, and primary normal hepatocytes using MTT assay. Inhibition of lactate/ATP production and intracellular reactive oxygen species generation by DCA and metformin was investigated. Inhibition of PI3K/Akt/mTOR complex I was evaluated to see whether it occurred through AMPK signaling. Anticancer effects of a combination treatment of DCA and metformin were evaluated in HCC murine model. The results showed that metformin and DCA effectively induced apoptosis in liver cancer cells. A combination treatment of metformin and DCA did not affect viability of primary normal hepatocytes. Metformin upregulated glycolysis in liver cancer cells, thereby increasing sensitivity to the DCA treatment. Metformin and DCA inhibited mTOR complex I signaling through upregulated AMPK-independent REDD1. In addition, metformin and DCA increased reactive oxygen species levels in liver cancer cells, which induced apoptosis. A combination treatment of metformin and DCA significantly suppressed the tumor growth of liver cancer cells using in vivo xenograft model. Taken together, the combined treatment of metformin and DCA suppressed the growth of liver cancer cells. This strategy may be effective for patients with advanced liver cancer.

Safe and Targeted Sonodynamic Cancer Therapy Using Biocompatible Exosome-Based Nanosonosensitizers

Sonodynamic therapy (SDT), wherein sonosensitizers irradiated with ultrasound (US) produce cytotoxic reactive oxygen species (ROS), has garnered great attention as a promising alternative to photodynamic therapy owing to the significantly increased depth of tissue penetration. The development of nanocarriers that can selectively deposit sonosensitizers into tumor tissues without systemic toxicity is crucial to facilitate the translation of SDT to clinical use. In this study, exosomes, a class of naturally occurring nanoparticles, were utilized as nanocarriers for safe and cancer-targeted delivery of a sonosensitizer, indocyanine green (ICG). The exosomes were surface-engineered with an active cancer-targeting ligand, folic acid (FA), to increase the cancer specificity of the ICG-loaded exosomes (ExoICG). The FA-conjugated, ICG-loaded exosomes (FA-ExoICG) greatly improved aqueous stability and cellular uptake of ICG, resulting in significantly increased ROS generation in breast cancer cells. As a result, the FA-ExoICG demonstrated greater sonotoxicity against cancer cells than ExoICG and free ICG. The in vivo study revealed that compared to ExoICG, more FA-ExoICG accumulated in tumors, and their pharmacokinetic properties were superior. Notably, tumor growth in mice was significantly suppressed, without systemic toxicity, by a single intravenous injection of the FA-ExoICG and subsequent US irradiation. Therefore, this study demonstrated that active cancer-targeted FA-ExoICG could serve as effective nanosonosensitizers for safe and targeted cancer treatment.

Solvent-driven, self-assembled acid-responsive poly(ketalized serine)/siRNA complexes for RNA interference

Advances in bionanotechnology aim to develop smart nucleic acid delivery carriers with stimuli-responsive features to overcome challenges such as non-biodegradability, rapid clearance, immune response, and reaching intracellular targets. Peptide-based nanomaterials have become widely used in the field of gene and drug delivery due to their structural versatility and biomimetic properties. Particularly, polypeptide gene vectors that respond to biological stimuli, such as acidic intracellular environments, have promising applications in mediating efficient endosomal escape and drug release. Unfortunately, synthesis strategies for efficient polymerization of acid-labile peptides have been limited due to conditions that fail to preserve acid-degradable functional groups. Stable urethane derivatives of the acid-labile amino acid ketalized serine (kSer) were synthesized and polymerized to a high molecular weight under permissive conditions independent of elevated temperature, restrictive solvents, or an inert atmosphere. A new formulation strategy utilizing solvent-driven self-assembly of poly(kSer) peptides with small interfering RNA (siRNA) was developed, and the resulting poly(kSer)/siRNA complexes were further cross-linked for reinforced stability under physiological conditions. The complexes were highly monodisperse and precisely spherical in morphology, which has significant clinical implications in definitive biodistribution, cellular internalization, and intracellular trafficking patterns. Self-assembled, cross-linked poly(kSer)/siRNA complexes demonstrated efficient nucleic acid encapsulation, internalization, endosomal escape, and acid-triggered cargo release, tackling multiple hurdles in siRNA delivery. The acid-responsive polypeptides and solvent-driven self-assembly strategies demonstrated in this study could be applicable to developing other efficient and safe delivery systems for gene and drug delivery.

Effects of Decomplexation Rates on Ternary Gene Complex Transfection with α-Poly(l-Lysine) or ε-Poly(l-Lysine) as a Decomplexation Controller in An Easy-To-Transfect Cell or A Hard-To-Transfect Cell

The tight binding of pDNA with a cationic polymer is the crucial requirement that prevents DNA degradation from undesired DNase attack to safely deliver the pDNA to its target site. However, cationic polymer-mediated strong gene holding limits pDNA dissociation from the gene complex, resulting in a reduction in transfection efficiency. In this study, to control the decomplexation rate of pDNA from the gene complex in a hard-to-transfect cell or an easy-to-transfect cell, either α-poly(l-lysine) (APL) or ε-poly(l-lysine) (EPL) was incorporated into branched polyethylenimine (bPEI)-based nanocomplexes (NCs). Compared to bPEI/pDNA NCs, the addition of APL or EPL formed smaller bPEI-APL/pDNA NCs with similar zeta potentials or larger bPEI-EPL/pDNA NCs with reduced zeta potentials, respectively, due to the different characteristics of the primary amines in the two poly(l-lysine)s (PLs). Interestingly, although both bPEI-APL/pDNA NCs and bPEI-EPL/pDNA NCs showed similar pDNA compactness to bPEI/pDNA NCs, the addition of APL or EPL resulted in slower or faster pDNA release, respectively, from the bPEI-PL/pDNA NCs than from the bPEI/pDNA NCs. bPEI-EPL/pDNA NCs with a decomplexation enhancer (i.e., EPL) improved the transfection efficiency (TE) in both a hard-to-transfect HepG2 cell and an easy-to-transfect HEK293 cell. However, although a decomplexation inhibitor (i.e., APL) reduced the TE of bPEI-APL/pDNA NCs in both cells, the degree of reduction in the TE could be compensated by PL-mediated enhanced nuclear delivery, particularly in HepG2 cells but not HEK293 cells, because both PLs facilitate nuclear localization of the gene complex per its cellular uptake. In conclusion, a decomplexation rate controller could be a potential factor to establish a high TE and design clinically available gene complex systems.

Mitochondria-targeted drug delivery in cancers

Mitochondria are considered one of the most important subcellular organelles for targeting and delivering drugs because mitochondria are the main location for various cellular functions and energy (i.e., ATP) production, and mitochondrial dysfunctions and malfunctions cause diverse diseases such as neurodegenerative disorders, cardiovascular disorders, metabolic disorders, and cancers. In particular, unique mitochondrial characteristics (e.g., negatively polarized membrane potential, alkaline pH, high reactive oxygen species level, high glutathione level, high temperature, and paradoxical mitochondrial dynamics) in pathological cancers have been used as targets, signals, triggers, or driving forces for specific sensing/diagnosing/imaging of characteristic changes in mitochondria, targeted drug delivery on mitochondria, targeted drug delivery/accumulation into mitochondria, or stimuli-triggered drug release in mitochondria. In this review, we describe the distinctive structures, functions, and physiological properties of cancer mitochondria and discuss recent technologies of mitochondria-specific "key characteristic" sensing systems, mitochondria-targeted "drug delivery" systems, and mitochondrial stimuli-specific "drug release" systems as well as their strengths and weaknesses.

Selective Anticancer Therapy Using Pro-Oxidant Drug-Loaded Chitosan-Fucoidan Nanoparticles

Pro-oxidant therapy exploiting pro-oxidant drugs that can trigger cytotoxic oxidative stress in cancer cells has emerged as an innovative strategy for cancer-specific therapy. Piperlongumine (PL) has gained great interest as a novel pro-oxidant agent, because it has an ability to trigger cancer-specific apoptosis through the increase of oxidative stress in cancer cells. However, the use of PL is limited in the clinic because of its hydrophobic nature. In this study, chitosan- and fucoidan-based nanoparticles were prepared for the effective intracellular delivery of PL into cancer cells. Chitosan and fucoidan formed nanoparticles by ionic gelation. The chitosan- and fucoidan-based nanoparticles (CS-F NPs) effectively encapsulated PL, and increased its water solubility and bioavailability. CS-F NPs showed very low cytotoxicity in human prostate cancer cells, demonstrating its high potential for in vivo applications. The PL-loaded chitosan-fucoidan nanoparticles (PL-CS-F NPs) efficiently killed human prostate cancer cells via PL-induced intracellular reactive oxygen species (ROS) generation. This study demonstrates that CS-F NPs are promising natural polymer-based drug carriers for safe and effective PL delivery.

Mitochondria-targeting drug conjugates for cytotoxic, anti-oxidizing and sensing purposes: current strategies and future perspectives

Mitochondrial targeting is a promising approach for solving current issues in clinical application of chemotherapy and diagnosis of several disorders. Here, we discuss direct conjugation of mitochondrial-targeting moieties to anticancer drugs, antioxidants and sensor molecules. Among them, the most widely applied mitochondrial targeting moiety is triphenylphosphonium (TPP), which is a delocalized cationic lipid that readily accumulates and penetrates through the mitochondrial membrane due to the highly negative mitochondrial membrane potential. Other moieties, including short peptides, dequalinium, guanidine, rhodamine, and F16, are also known to be promising mitochondrial targeting agents. Direct conjugation of mitochondrial targeting moieties to anticancer drugs, antioxidants and sensors results in increased cytotoxicity, anti-oxidizing activity and sensing activity, respectively, compared with their non-targeting counterparts, especially in drug-resistant cells. Although many mitochondria-targeted anticancer drug conjugates have been investigated in vitro and in vivo, further clinical studies are still needed. On the other hand, several mitochondria-targeting antioxidants have been analyzed in clinical phases I, II and III trials, and one conjugate has been approved for treating eye disease in Russia. There are numerous ongoing studies of mitochondria-targeted sensors.

Microfluidic fabrication of biocompatible poly(N-vinylcaprolactam)-based microcarriers for modulated thermo-responsive drug release

Various thermo-responsive polymers have been developed for controlled drug delivery upon the local application of external heat. The development of thermo-responsive polymers with high biocompatibility and tunable thermo-sensitivity is crucial for safe and efficient therapeutic application. In this study, thermo-responsive drug carriers featuring tunable thermo-sensitivities were synthesized using biocompatible poly(N-vinyl caprolactam) (PVCL) and stop-flow lithography. The PVCL-based particles showed selective drug release depending on temperature, illustrating their feasibility for on-demand controlled drug delivery. The volume phase transition temperature (VPTT) of the PVCL-based particles can be adjusted to vary from room temperature to body temperature by controlling their monomer compositions. In addition, modulated drug release was achieved by constructing multicompartments of different thermo-sensitivities within the PVCL particles. To accomplish thermo-responsive anticancer therapy, doxorubicin (DOX) was encapsulated into the PVCL particles as an anticancer drug. The DOX-loaded PVCL particles exhibited both thermo-responsive drug release and anticancer activity. This study demonstrates that thermo-responsive PVCL particles are highly promising carriers for safe and targeted anticancer therapy.

Targeted siRNA delivery using aptamer-siRNA chimeras and aptamer-conjugated nanoparticles

The sequence-specific gene-silencing ability of small interfering RNA (siRNA) has been exploited as a new therapeutic approach for the treatment of a variety of diseases. However, efficient and safe delivery of siRNA into target cells is still a challenge in the clinical development of siRNA-based therapeutics. Recently, nucleic acid-based aptamers that target cell surface proteins have emerged as a new class of targeting moieties due to their high specificity and avidity. To date, various aptamer-mediated siRNA delivery systems have been developed to enhance the RNA interference (RNAi) efficacy of siRNA via targeted delivery. In this review, we summarize recent advances in developing aptamer-mediated siRNA delivery systems for RNAi therapeutics, mainly aptamer-siRNA chimeras and aptamer-functionalized nanocarriers incorporating siRNA, with a focus on their molecular designs and formulations. In addition, the challenges and engineering strategies of aptamer-mediated siRNA delivery systems for clinical translation are discussed. This article is categorized under: Biology-Inspired Nanomaterials > Nucleic Acid-Based Structures Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease.

Photo-triggered antibacterial and anticancer activities of zinc oxide nanoparticles

ZnO nanoparticles (ZnO NPs) have gained more attention in recent years due to their ability to induce the generation of reactive oxygen species (ROS) under light irradiation. Photo-triggered ROS generation by ZnO NPs and the resulting phototoxicity in cells have found use in antibacterial and anticancer applications. This review highlights recent advances in the development of ZnO NPs and hybrid-type functionalized ZnO NPs for photo-triggered antibacterial and anticancer activities. In addition, various chemical modifications including metal doping, metal hybridization, modification with polymers, and sensitization by organic photosensitizers have been further introduced to enhance the photocatalytic efficiency and ROS generation capability of ZnO NPs. The enhanced ROS generation efficiency of modified ZnO NPs consequently increases their antibacterial and anticancer activities. Additionally, we offer some insights into the design and engineering of next-generation ZnO NPs for more effective antibacterial and anticancer applications.

Transradial versus transfemoral intervention in ST-segment elevation myocardial infarction patients in Korean population

BACKGROUND/AIMS

Transradial intervention (TRI) is becoming the preferred method over transfemoral intervention (TFI) because TRI is associated with lower incidence of major bleeding and vascular complications. However, there has been limited published data regarding the clinical outcomes of TRI versus TFI in Korean patients with ST-elevation myocardial infarction (STEMI).

METHODS

A total of 689 consecutive STEMI patients who underwent primary percutaneous coronary intervention (PCI) with drug-eluting stents (DESs) from January to December of 2009 at nine university hospitals were enrolled in this study. Mid-term angiographic and 12-month cumulative clinical outcomes of the TRI group (n = 220, 31.9%) were compared to those of the TFI group (n = 469, 28.1%).

RESULTS

After propensity score matching, in-hospital complications and the 12-month major clinical outcomes during follow-up in the two groups were similar to each other. However, the incidence rates of repeat revascularization (6.4% vs. 0.5%, p = 0.003), target vessel revascularization (6.4% vs. 0.5%, p = 0.003), and major adverse cardiac events (MACE; 11.6% vs. 4.6%, p = 0.018) in the TFI group were higher than those in the TRI group during the 12-month of follow-up.

CONCLUSIONS

In our study, TRI in STEMI patients undergoing primary PCI with DESs was associated with lower incidence of access site hematoma, 12-month repeat revascularization, and MACE compared to TFI. Therefore, TRI might play an important role in reducing bleeding complications while improving major clinical outcomes in STEMI patients undergoing primary PCI with DESs.

Preparation, Characterization and Biological Applications of Biosynthesized Silver Nanoparticles with Chitosan-Fucoidan Coating

Silver nanoparticles (AgNPs) are gaining a great deal of attention in biomedical applications due to their unique physicochemical properties. In this study, green synthesis of AgNPs was developed using seaweed polysaccharide fucoidan. The AgNPs were further coated with chitosan to form an electrolyte complex on the surface. The developed chitosan⁻fucoidan complex-coated AgNPs were characterized using UV-visible spectroscopy, Fourier transform infrared spectroscopy (FT-IR), and transmission electron microscopy (TEM). FT-IR results suggested strong polyelectrolyte complexation between fucoidan and chitosan. The developed chitosan⁻fucoidan complex-coated AgNPs significantly inhibited microbial growth. Moreover, the AgNPs showed efficient anticancer activity in human cervical cancer cells (HeLa). This study demonstrated that chitosan⁻fucoidan complex-coated AgNPs hold high potential for food and cosmeceutical applications.

Fabrication of dual stimuli-responsive multicompartmental drug carriers for tumor-selective drug release

There has been increasing attention to the development of multi-stimuli-responsive drug carriers for precisely controlled drug release at target disease areas. In this study, pH- and redox-responsive hybrid drug carriers were fabricated by using both ketal-based acid-cleavable precursors and disulfide-based reducible precursors via stop-flow lithography. pH- and redox-sensitive drug release of the dual stimuli-responsive hybrid particles was confirmed, demonstrating their feasibility for selective and efficient drug release into tumor tissues in acidic and highly reductive environments. It was also found that the drug release rate of the particles was fine-tuned by modulating monomer compositions in the precursor. Importantly, the dual stimuli-responsive hybrid particles exhibited synergistic, controlled drug release in complex stimuli (both pH and redox stimuli) environments. To achieve tumor-selective combination chemotherapy, multicompartmental drug carriers consist of an acid-degradable compartment and a reducible compartment, which can separately encapsulate individual model drugs in each of the compartments. The multicompartmental particles exhibited independent drug release upon exposure to the corresponding stimulus. The dual stimuli-responsive, multicompartmental particles are effective drug carriers for tumor-selective release of a drug cocktail, leading to synergistic combination chemotherapy.

Bioreducible Polymer Micelles Based on Acid-Degradable Poly(ethylene glycol)-poly(amino ketal) Enhance the Stromal Cell-Derived Factor-1α Gene Transfection Efficacy and Therapeutic Angiogenesis of Human Adipose-Derived Stem Cells

Adipose-derived stem cells (ADSCs) have the potential to treat ischemic diseases. In general, ADSCs facilitate angiogenesis by secreting various pro-angiogenic growth factors. However, transplanted ADSCs have a low therapeutic efficacy in ischemic tissues due to their poor engraftment and low viability. Stromal cell-derived factor-1α (SDF-1α) improves the survival rate of stem cells transplanted into ischemic regions. In this study, we developed acid-degradable poly(ethylene glycol)-poly(amino ketal) (PEG-PAK)-based micelles for efficient intracellular delivery of SDF-1α plasmid DNA. The SDF-1α gene was successfully delivered into human ADSCs (hADSCs) using PEG-PAK micelles. Transfection of SDF-1α increased SDF-1α, vascular endothelial growth factor, and basic fibroblast growth factor gene expression and decreased apoptotic activity in hADSCs cultured under hypoxic conditions in comparison with conventional gene transfection using polyethylenimine. SDF-1α-transfected hADSCs also showed significantly increased SDF-1α and VEGF expression together with reduced apoptotic activity at 4 weeks after transplantation into mouse ischemic hindlimbs. Consequently, these cells improved angiogenesis in ischemic hindlimb regions. These PEG-PAK micelles may lead to the development of a novel therapeutic modality for ischemic diseases based on an acid-degradable polymer specialized for gene delivery.

Angiotensin-converting enzyme inhibitors versus angiotensin II receptor blockers in acute ST-segment elevation myocardial infarction patients with diabetes mellitus undergoing percutaneous coronary intervention

BACKGROUND

Diabetes Mellitus (DM) is an important factor of adverse cardiovascular events in acute ST-segment elevation myocardial infarction (STEMI) patients. Renin-angiotensin-aldosterone system (RAAS) inhibitors is associated with improved clinical outcomes, however, there are limited data comparing the effectiveness of two different RAAS inhibitors in STEMI patients with DM undergoing percutaneous coronary intervention (PCI) with drug-eluting stents (DES).

METHODS

A total of 3811 eligible STEMI patients with DM were enrolled in Korea Acute Myocardial Infarction Registry (KAMIR). They were stratified into two groups: Angiotensin converting enzyme inhibitors (ACEI) group (n=2691) and angiotensin receptor blockers (ARB) group (n=1120). To adjust baseline confounding factors, we performed propensity score matching (PSM) analysis and evaluated individual and composite major clinical outcomes between the two groups up to 2years.

RESULTS

After PSM, a total of 1049 well-matched pairs were generated. Baseline clinical, angiographic and procedural characteristics were well-balanced between the two groups. The incidence of death, recurrent myocardial infarction (MI), revascularization and major adverse cardiac events (MACE) were not significantly different between the two groups up to 2years, CONCLUSION: In the present study, ACEI and ARB showed comparable effectiveness and safety on individual and composite clinical outcomes in STEMI patients with DM who underwent successful PCI with DES at least up to 2years.

Chitosan as a vehicle for growth factor delivery: Various preparations and their applications in bone tissue regeneration

The replacement of conventional autografts and allografts by bone fragments constructed from alternate materials, cells, and molecules (growth factors, drugs, etc.) is an exciting prospect in the field of bone tissue engineering. Bone morphogenetic protein-2 (BMP-2) is a growth factor that has been extensively studied from this point of view. This review analyzes the relevance of chitosan and its derivatives and composites with various materials such as ceramics, heparin, silica, stem cells, titanium implants, etc., in terms of delivering BMP-2 for the purpose of bone regeneration. Chitosan offers the versatility to be modified into any shapes or sizes including conversion to nanoparticles, microspheres, nanofibers, porous scaffolds, and films. The results presented in this review clearly demonstrate that chitosan-based materials are biocompatible and have the potential to systematically and sustainably release BMP-2 where required. This release results in enhanced cell proliferation levels, enhancement of alkaline phosphatase activity, increased differentiation as well as increased mineralization under in vitro and in vivo conditions. This review also shines a spotlight on the currently developed chitosan-based products that are being used for BMP-2 delivery.

Antimicrobial, Antioxidant, and Anticancer Activities of Biosynthesized Silver Nanoparticles Using Marine Algae Ecklonia cava

Green synthesis of silver nanoparticles (AgNPs) has gained great interest as a simple and eco-friendly alternative to conventional chemical methods. In this study, AgNPs were synthesized by using extracts of marine algae Ecklonia cava as reducing and capping agents. The formation of AgNPs using aqueous extract of Ecklonia cava was confirmed visually by color change and their surface plasmon resonance peak at 418 nm, measured by UV-visible spectroscopy. The size, shape, and morphology of the biosynthesized AgNPs were observed by transmission electron microscopy and dynamic light scattering analysis. The biosynthesized AgNPs were nearly spherical in shape with an average size around 43 nm. Fourier transform-infrared spectroscopy (FTIR) analysis confirmed the presence of phenolic compounds in the aqueous extract of Ecklonia cava as reducing and capping agents. X-ray diffraction (XRD) analysis was also carried out to demonstrate the crystalline nature of the biosynthesized AgNPs. Antimicrobial results determined by an agar well diffusion assay demonstrated a significant antibacterial activity of the AgNPs against Escherichia coli and Staphylococcus aureus. Antioxidant results determined by 1,1-diphenyl-2-picrylhydrazyl (DPPH) scavenging assay revealed an efficient antioxidant activity of the biosynthesized AgNPs. The biosynthesized AgNPs also exhibited a strong apoptotic anticancer activity against human cervical cancer cells. Our findings demonstrate that aqueous extract of Ecklonia cava is an effective reducing agent for green synthesis of AgNPs with efficient antimicrobial, antioxidant, and anticancer activities.

Impact of Cigarette Smoking: a 3-Year Clinical Outcome of Vasospastic Angina Patients

Background and Objectives

Cigarette smoking is a risk significant factor in coronary artery disease (CAD) and vasospastic angina (VSA). However, it is largely unknown whether smoking adds to any long-term clinical risk in VSA patients.

Subjects and Methods

A total of 2797 patients without significant CAD underwent acetylcholine (Ach) provocation test between November 2004 and October 2010. Patients were divided into three groups, based on the presence of coronary artery spasm (CAS) and smoking habits (non-CAS group: n=1188, non-smoking CAS group: n=1214, smoking CAS group: n=395). All CAS patients were prescribed with anti-anginal medications for at least 6 months. The incidence of major clinical outcomes and recurrent angina of these groups were compared up to 3 years.

Results

There were considerable differences in the baseline clinical and angiographic characteristics among the three groups, but there was no difference in the endpoints among the three groups (including individual and composite hard endpoints) such as death, myocardial infarction, de novo percutaneous coronary intervention, cerebrovascular accident, and major adverse cardiac events. However, there was a higher incidence of recurrent angina in both the non-smoking CAS group and smoking CAS group, as compared to the non-CAS group. In multivariable adjusted Cox-proportional hazards regression analysis, smoking CAS group exhibited a higher incidence of recurrent angina compared with the non-CAS group (hazard ratio [HR]; 2.46, 95% confidence interval [CI]; 1.46-4.14, p=0.001) and non-smoking CAS group (HR; 1.76, 95% CI; 1.08-2.87, p=0.021).

Conclusion

Cigarette smoking CAS group exhibited higher incidence of recurrent angina during the 3-year clinical follow-up compared with both the non-CAS group and non-smoking CAS group. Quitting of smoking, paired with intensive medical therapy and close clinical follow-up, can help to prevent recurrent angina.

Impact of Renin-Angiotensin System Inhibitors on Long-Term Clinical Outcomes of Patients With Coronary Artery Spasm

Background

Coronary artery spasm (CAS) is a well‐known endothelial dysfunction, and a major cause of vasospastic angina (VSA). The renin–angiotensin system (RAS) is known to be closely associated with endothelial function. However, there are only a few studies that investigated the impact of RAS inhibitor on long‐term clinical outcomes in VSA patients.

Methods and Results

A total of 3349 patients with no significant coronary artery disease, diagnosed with CAS by acetylcholine provocation test were enrolled for this study. Significant CAS was defined as having ≥70% narrowing of the artery after incremental injections of 20, 50, and 100 μg of acetylcholine into the left coronary artery. Patients were divided into 2 groups according to whether the prescription included RAS inhibitor or not (RAS inhibitor group: n=666, non‐RAS inhibitor group; n=2683). To adjust for any potential confounders that could cause bias, propensity score matching (PSM) analysis was performed using a logistic regression model. After PSM analysis, 2 matched groups (524 pairs, n=1048 patients, C‐statistic=0.845) were generated and their baseline characteristics were balanced. During the 5‐year clinical follow‐up, the RAS inhibitor group showed a lower incidence of recurrent angina (8.7% versus 14.1%, P=0.027), total death (0.0% versus 1.3%, P=0.045), and total major adverse cardiovascular events (1.0% versus 4.1%, P=0.026) than the non‐RAS inhibitor group.

Conclusions

Chronic RAS inhibitor therapy was associated with lower incidence of cardiovascular events in VSA patients in the 5‐year clinical follow‐up.

Targeted and effective photodynamic therapy for cancer using functionalized nanomaterials

Photodynamic therapy (PDT) is an emerging, non-invasive therapeutic strategy that involves photosensitizer (PS) drugs and external light for the treatment of diseases. Despite the great progress in PS-mediated PDT, their clinical applications are still hampered by poor water solubility and tissue/cell specificity of conventional PS drugs. Therefore, great efforts have been made towards the development of nanomaterials that can tackle fundamental challenges in conventional PS drug-mediated PDT for cancer treatment. This review highlights recent advances in the development of nano-platforms, in which various functionalized organic and inorganic nanomaterials are integrated with PS drugs, for significantly enhanced efficacy and tumor-selectivity of PDT.

Microfluidic Synthesis of pH-Sensitive Multicompartmental Microparticles for Multimodulated Drug Release

Stimuli-responsive carriers releasing multiple drugs have been researched for synergistic combinatorial cancer treatment with reduced side-effects. However, previously used drug carriers have limitations in encapsulating multiple drug components in a single carrier and releasing each drug independently. In this work, pH-sensitive, multimodulated, anisotropic drug carrier particles are synthesized using an acid-cleavable polymer and stop-flow lithography. The particles exhibit a faster drug release rate at the acidic pH of tumors than at physiological pH, demonstrating their potential for tumor-selective drug release. The drug release rate of the particles can be adjusted by controlling the monomer composition. To accomplish multimodulated drug release, multicompartmental particles are synthesized. The drug release profile of each compartment is programmed by tailoring the monomer composition. These pH-sensitive, multicompartmental particles are promising drug carriers enabling tumor-selective and multimodulated release of multiple drugs for synergistic combination cancer therapy.

"Combo" nanomedicine: Co-delivery of multi-modal therapeutics for efficient, targeted, and safe cancer therapy

The dynamic and versatile nature of diseases such as cancer has been a pivotal challenge for developing efficient and safe therapies. Cancer treatments using a single therapeutic agent often result in limited clinical outcomes due to tumor heterogeneity and drug resistance. Combination therapies using multiple therapeutic modalities can synergistically elevate anti-cancer activity while lowering doses of each agent, hence, reducing side effects. Co-administration of multiple therapeutic agents requires a delivery platform that can normalize pharmacokinetics and pharmacodynamics of the agents, prolong circulation, selectively accumulate, specifically bind to the target, and enable controlled release in target site. Nanomaterials, such as polymeric nanoparticles, gold nanoparticles/cages/shells, and carbon nanomaterials, have the desired properties, and they can mediate therapeutic effects different from those generated by small molecule drugs (e.g., gene therapy, photothermal therapy, photodynamic therapy, and radiotherapy). This review aims to provide an overview of developing multi-modal therapies using nanomaterials ("combo" nanomedicine) along with the rationale, up-to-date progress, further considerations, and the crucial roles of interdisciplinary approaches.