Canola bee pollen is an effective artificial diet additive for improving larval development of predatory coccinellids: a lesson from Harmonia axyridis.

BACKGROUND: Pollen is a common plant-derived food source for predatory ladybird beetles under field conditions, yet the potential for pollen to improve the quality of artificial diets remains largely unexplored. In this study, we developed three pollen diets by incorporating varying proportions of canola bee pollen (7.5%, 15.0% and 22.5% with 2.5%, 5.0%, and 7.5% of water, respectively) into a conventional diet. The feeding efficiency of Harmonia axyridis, an omnivorous predator, was evaluated and compared on three pollen diets, a conventional nonpollen diet and pea aphids. RESULTS: The larvae fed a medium or high pollen diet exhibited significantly higher survival in the 4th instar, pupa and adult stages than those fed a nonpollen diet. These larvae also developed into significantly heavier adults, and their survival rates in adulthood were comparable to those fed pea aphids. Specifically, we revealed the underlying mechanisms through which a high pollen diet enhances pupal development. Consumption of high pollen diet versus nonpollen diet resulted not only in a significant decrease in pupal glycogen content, but also an increase in adult lipid content. Both diet treatments induced similar changes in carbohydrate and glycogen content compared to the aphid diet while exhibiting different alterations in pupal protein content and adult lipid content. Furthermore, the transcriptome analysis revealed that the nutrient metabolism, immune response, and cuticle development pathways were predominantly enriched among the differentially expressed genes (DEGs). CONCLUSION: Canola bee pollen offers diverse advantages in terms of rearing H. axyridis larvae with an artificial diet, which will advance the development of effective diets for predaceous coccinellids. © 2024 Society of Chemical Industry.

The Expression of LDL-R in CD8+ T Cells Serves as an Early Assessment Parameter for the Production of TCR-T Cells.

BACKGROUND/AIM: The quantity and the phenotypes of desired T cell receptor engineered T (TCR-T) cells in the final cell product determine their in vivo anti-tumor efficacy. Optimization of key steps in the TCR-T cell production process, such as T cell activation, has been shown to improve cell quality. MATERIALS AND METHODS: Using a modified TCR (mTCR) derived from mice transducing PBMCs, we assessed the proportions of low-density lipoprotein receptor (LDL-R) and mTCR expressing cells under the various activation conditions of CD3/CD28-Dynabeads or OKT3 via flow cytometry. RESULTS: We demonstrate that the proportion of T cells expressing LDL-R post activation is positively correlated with the percentage of mTCR+CD8+ T cells with their less differentiated subtypes in the final product. In addition, we show that shifting the CD3/CD28-Dynabeads activation duration from a typical 48 h to 24 h can significantly increase the production of the desired mTCR+CD8+ T cells. Importantly, the percentages of TCR-T cells with less-differentiated phenotypes, namely mTCR central memory T cells (TCM), were found to be preserved with markedly higher efficiency when T cell activation was optimized. CONCLUSION: Our findings suggest that the proportion of LDL-R+ T cells may serve as an early assessment parameter for evaluating TCR-T cell quality, possibly facilitating the functional and economical improvement of current adoptive therapy.

Extended SARS-CoV-2 RBD booster vaccination induces humoral and cellular immune tolerance in mice.

The repetitive applications of vaccine boosters have been brought up in face of continuous emergence of SARS-CoV-2 variants with neutralization escape mutations, but their protective efficacy and potential adverse effects remain largely unknown. Here, we compared the humoral and cellular immune responses of an extended course of recombinant receptor binding domain (RBD) vaccine boosters with those from conventional immunization strategy in a Balb/c mice model. Multiple vaccine boosters after the conventional vaccination course significantly decreased RBD-specific antibody titers and serum neutralizing efficacy against the Delta and Omicron variants, and profoundly impaired CD4+ and CD8+T cell activation and increased PD-1 and LAG-3 expressions in these T cells. Mechanistically, we confirmed that extended vaccination with RBD boosters overturned the protective immune memories by promoting adaptive immune tolerance. Our findings demonstrate potential risks with the continuous use of SARS-CoV-2 vaccine boosters, providing immediate implications for the global COVID-19 vaccination enhancement strategies.

Ginkgolide B improved postoperative cognitive dysfunction by inhibiting microgliosis-mediated neuroinflammation in the hippocampus of mice.

BACKGROUND: Postoperative cognitive dysfunction (POCD) are a common complication of the central nervous system following surgery and anesthesia. The specific pathogenesis and effective therapeutics of POCD need to be further studied. Ginkgolide B (GB), a platelet-activating factor receptor-specific antagonist, has been suggested to have strong anti-inflammatory effects. Here we tested the effects and mechanism of GB on POCD of aged rats. METHODS: Neurobehavioral tests were used to investigate the effect of GB pretreatment on POCD. The hippocampus were harvested to test the expression of proinflammatory cytokines by ELISA. The expression of the microglial marker ionized calcium-binding adaptor molecule-1 (Iba-1) in the hippocampus was evaluated by western blot assay and immunohistochemistry. A Nissl staining experiment was used to detect the neuronal numbers in the hippocampus. RESULTS: Surgery might result in the overexpression of platelet activating factor (PAF) in the plasma and hippocampus and might cause hippocampus-dependent memory impairment. GB pretreatment, inhibited the activation of microglia, reduced the levels of IL-1ß and TNF-α, decreased the loss of neurons after surgery, and prevented POCD in aged rats. CONCLUSION: Our findings suggested that PAF was involved in the development of POCD. Improvement of POCD by PAF antagonist GB was associated with the inhibition of microgliosis-mediated neuroinflammation and neuronal apoptosis in aged rats.

Discovery of glyantrypine-family alkaloids as novel antiviral and antiphytopathogenic-fungus agents.

BACKGROUND: Plant diseases caused by viruses and fungi have caused great losses to crop quality and yield. The discovery of novel and efficient antiviral and antiphytopathogenic-fungus agents is urgently needed. It is the most important pesticide innovation strategy to find active compounds from natural products. Here, glyantrypine-family alkaloids were taken as the parent structures and a series of their derivatives were designed through molecular splicing, ring expansion, and ring contraction strategies, and synthesized. The anti-tobacco mosaic virus (TMV) activities and antifungal activities of these alkaloids were systematically investigated for the first time. RESULT: The antiviral activities of compounds 7bb, 7bc, 11c, 18b, 18d, 28d, and 28e are equivalent to or better than that of ribavirin (inhibitory rates 39%, 37%, and 40% at 500 µg mL-1 for inactivation, curative, and protection activity in vivo, respectively). Compounds 18d and 28d with good antiviral activities were selected for antiviral mode of action studies, which indicated that these alkaloids could achieve good antiviral effects by inhibiting TMV particle extension during assembly. These compounds also exhibited broad-spectrum fungicidal activities. CONCLUSION: Glyantrypine-family alkaloids and their derivatives were synthesized and evaluated for anti-TMV and fungicidal activities for the first time. Compounds 18d and 28d with excellent antiviral activities and compound 7bc with remarkable fungicidal activity emerged as novel lead compounds. This study lays a foundation for the application of glyantrypine alkaloids in plant protection.

Paclitaxel-based supramolecular hydrogel loaded with mifepristone for the inhibition of breast cancer metastasis.

Breast cancer is the leading cause of cancer death among women and almost all of the breast cancer-caused mortality is related to metastasis. It has been reported that glucocorticoid facilitates the metastasis of breast cancer in mice, and mifepristone can antagonize the effect of glucocorticoid. Paclitaxel is one of the important drugs in the treatment of breast cancer. Mifepristone combined with paclitaxel could be an effective strategy for inhibiting breast cancer metastasis. However, their inherent defects, in terms of short blood circulation half-life and lack of tumor targeting, not only limit their effectiveness but also cause adverse reactions. Therefore, our aim is to explore a novel protocol against breast cancer metastasis, further optimize its therapeutic efficacy by a nanodelivery system, and explore its mechanism. Herein, a paclitaxel-conjugated and mifepristone-loaded hydrogel (PM-nano) was prepared by self-assembly. Its characterizations were studied. The antimetastatic effect was evaluated in vitro and in vivo and its mechanism was also explored by western blot assay. The resultant PM-nano was developed with favorable water solubility and good biocompatibility. Moreover, PM-nano displayed increased cell uptake properties and stimulated drug release in the tumor micro-acidic environment. The PM-nano was more effective in inhibiting the proliferation and metastasis of breast cancer than other groups in vitro and in vivo. The PM-nano might inhibit metastasis through glucocorticoid receptor/receptor tyrosine kinase-like orphan receptor 1 and MMPs. Taken together, PM-nano showed superior antimetastatic effects against breast cancer and excellent biocompatibility in vitro and in vivo, providing a new option for limiting metastasis.

Mutual Benefit between Cu(II) and Polydopamine for Improving Photothermal-Chemodynamic Therapy.

Combination therapy has attracted extensive interest in alleviating the shortcomings of monotherapy and enhancing the treatment efficacy. In this work, hollow mesoporous silica nanoparticles (HMSNs) play the role of nanocarriers in the delivery of Cu(II)-doped polydopamine (PDA), termed as HMSNs@PDA-Cu, for synergistic therapy. PDA acts as a traditional photothermal agent to realize photothermal treatment (PTT). Chemodynamic therapy (CDT) is realized by the reaction of Cu(II) with intracellular glutathione (GSH), and subsequently, the generated Cu(I) reacts with H2O2 to produce toxic hydroxyl radical (•OH) through a Fenton-like reaction. The photothermal performance of PDA is improved after its coordination with Cu(II). On the other hand, PDA exhibits superoxide dismutase (SOD)-mimicking activity. PDA converts O2•- to H2O2 and improves the production of H2O2, which promotes the therapeutic effect of CDT. Moreover, the high temperature caused by PTT further enhances the yield of •OH for CDT. This nanotheranostic platform perfectly applied to the tumor depletion of mice, presenting great potential for cancer metastasis therapy in vitro and in vivo.

Construction of Novel Nanocomposites (Cu-MOF/GOD@HA) for Chemodynamic Therapy.

The emerging chemodynamic therapy (CDT) has received an extensive attention in recent years. However, the efficiency of CDT is influenced due to the limitation of H2O2 in tumor. In this study, we designed and synthesized a novel core-shell nanostructure, Cu-metal organic framework (Cu-MOF)/glucose oxidase (GOD)@hyaluronic acid (HA) (Cu-MOF/GOD@HA) for the purpose of improving CDT efficacy by increasing H2O2 concentration and cancer cell targeting. In this design, Cu-MOF act as a CDT agent and GOD carrier. Cu(II) in Cu-MOF are reduced to Cu(I) by GSH to obtain Cu(I)-MOF while GSH is depleted. The depletion of GSH reinforces the concentration of H2O2 in tumor to improve the efficiency of CDT. The resultant Cu(I)-MOF catalyze H2O2 to generate hydroxyl radicals (·OH) for CDT. GOD can catalyze glucose (Glu) to supply H2O2 for CDT enhancement. HA act as a targeting molecule to improve the targeting ability of Cu-MOF/GOD@HA to the tumor cells. In addition, after loading with GOD and coating with HA, the proportion of Cu(I) in Cu-MOF/GOD@HA is increased compared with the proportion of Cu(I) in Cu-MOF. This phenomenon may shorten the reactive time from Cu-MOF to Cu(I)-MOF. The CDT enhancement as a result of GOD and HA effects in Cu-MOF/GOD@HA was evidenced by in vitro cell and in vivo animal studies.

Flexible and Stretchable Capacitive Sensors with Different Microstructures.

Recently, sensors that can imitate human skin have received extensive attention. Capacitive sensors have a simple structure, low loss, no temperature drift, and other excellent properties, and can be applied in the fields of robotics, human-machine interactions, medical care, and health monitoring. Polymer matrices are commonly employed in flexible capacitive sensors because of their high flexibility. However, their volume is almost unchanged when pressure is applied, and they are inherently viscoelastic. These shortcomings severely lead to high hysteresis and limit the improvement in sensitivity. Therefore, considerable efforts have been applied to improve the sensing performance by designing different microstructures of materials. Herein, two types of sensors based on the applied forces are discussed, including pressure sensors and strain sensors. Currently, five types of microstructures are commonly used in pressure sensors, while four are used in strain sensors. The advantages, disadvantages, and practical values of the different structures are systematically elaborated. Finally, future perspectives of microstructures for capacitive sensors are discussed, with the aim of providing a guide for designing advanced flexible and stretchable capacitive sensors via ingenious human-made microstructures.

State-of-the-art advances of copper-based nanostructures in the enhancement of chemodynamic therapy.

Chemodynamic therapy (CDT) is a new emerging strategy for the in situ treatment of tumors. In the microenvironment of tumor cells, CDT may be achieved through the generation of reactive oxygen species (ROS), e.g., hydroxyl radicals (˙OH) and singlet oxygen (1O2), which induce the death of tumor cells. Copper (Cu) or other transition-metal ions catalyze the production of ˙OH by hydrogen peroxide (H2O2) through Fenton or Fenton-like reactions. With the development of advanced nanotechnology, nanotherapeutic systems with Cu-based nanostructures have received extensive attention and have been demonstrated for their wide applications in the design and construction of nanotherapeutic systems for CDT, along with multimodal synergistic therapy. Herein, the cutting-edge developments of Cu-based nanostructures in CDT are reviewed and discussed, by focusing on the monotherapy of CDT as well as synergistic treatments by hyphenating CDT with various therapeutic protocols, e.g., photothermal therapy (PTT), photodynamic therapy (PDT), sonodynamic therapy (SDT), and so on. In addition, the potential challenges and future perspectives are described in the improvement of CDT therapeutic efficacy, the enhancement of targeting capability, and mechanistic investigations on CDT therapy.

A fluorescence imaging protocol for correlating intracellular free cationic copper to the total uptaken copper by live cells.

A variety of fluorescence probes have been developed for fluorescence imaging of metals in biological cells. However, accurate quantification of metals with fluorescent approaches is challenging due to the difficulty in establishing a standard calibration curve in living cells. Herein, a fluorescence imaging protocol is developed for imaging intracellular Cu2+ and its correlation with the cellular uptake of copper. The total amount of intracellular Cu is detected by inductively coupled plasma mass spectrometry (ICP-MS) in parallel. Fluorescence imaging of Cu2+ is accomplished with Rhodamine B derivative modified carbon dots (CDs-Rbh) based on fluorescence resonance energy transfer (FRET) from CDs to rhodamine. Intracellular Cu2+ is correlated with fluorescence ratio at λem 500-600 nm (rhodamine) to λem 425-475 nm (CDs) with excitation at λex 405 nm. It is found that Cu2+ is linearly correlated with the total intracellular uptaken copper content, with a linear correlation between the relative fluorescence ratio in fluorescence imaging and intracellular Cu derived from ICP-MS, including both Cu(I) and Cu(II) species. The linear calibration equation is lg(F2/F1) = 0.00148 m[Cu]-0.3622. This approach facilitates further investigation and elucidation of copper transition in live cells and the evaluation of their cytotoxicity.

Functional morphology of antennae and sensilla of Hippodamia variegata (Coleoptera: Coccinellidae).

The lady beetle Hippodamia variegata is an important biocontrol agent of many aphids. In this study, the fine morphology of antennae as well as the typology, morphology and distribution of antennal sensilla were comprehensively examined by scanning electron microscopy. The antennal morphology of female and male are similar and consist of the scape, pedicel, and nine flagellomeres. No significant difference was detected in the length of each segment between two sexes, while the male antennae are much stronger than females. In total, six types of sensilla can be defined on antenna, including Böhm bristle, sensilla chaetica (with three subtypes), sensilla basiconica (with three subtypes), sensilla trichodea, sensilla placodea and sensilla coeloconica. It is worth noting that sensilla chaetica III distributed only on the fixed position of male antennae. In addition, the functional morphology of antennae of H. variegata were compared with other lady beetles from multiple perspectives. Specially, the function of sensilla were also discussed according to their morphology, location and information from previous studies.

Poly(ionic liquid)-Gated CuCo2S4 for pH-/Thermo-Triggered Drug Release and Photoacoustic Imaging.

A novel hybrid drug nanocarrier is developed with CuCo2S4 nanoparticles as the core to be encapsulated by poly(ionic liquid) (PIL), that is, poly(tetrabutylphosphonium styrenesulfonate) (P[P4,4,4,4][SS]), as the shell. Doxorubicin (DOX) is loaded onto the PIL shell via electrostatic attraction involving amine in DOX and styrenesulfonate in PIL. pH- and thermal-responsive characteristics of P[P4,4,4,4][SS] endow the multifunctional hybrid nanocarrier system DOX-CuCo2S4@PIL with sensitive dual-stimuli-triggered drug release behaviors. The CuCo2S4 core converts near-infrared (NIR) irradiation into thermal energy to trigger the shrinkage of the PIL shell, which subsequently promotes drug release, and the pH-responsive release of DOX involves pH-sensitive electrostatic interaction of the PIL shell with DOX. A favorable controlled release of 90.5% is achieved under pH/thermo dual stimuli. In vitro experiments with MCF-7 cells well demonstrated that the drug release is controlled by the acidic intracellular environment with NIR irradiation. The CuCo2S4 core also serves as a photoacoustic (PA) imaging contrast agent, as demonstrated by in vivo treatment of the MCF-7-carrying mice.

Marine-natural-products for biocides development: first discovery of meridianin alkaloids as antiviral and anti-phytopathogenic-fungus agents.

BACKGROUND: Food is an important strategic material related to national economy and people's livelihood. Plant diseases seriously affect crop yield and quality. Marine natural products are an important source for novel drugs discovery. In this work, meridianin alkaloids were selected as the parent structure. A series of meridianin alkaloid analogues were rationally designed, synthesized and evaluated for their antiviral activities and fungicidal activities. RESULT: These compounds were found to have good antiviral and fungicidal activities for the first time. The structure-activity relationship (SAR) research revealed that introducing bromine atom at the 5-position of indole ring is beneficial to antiviral activity, but introducing methoxy group is not conducive. Introducing bromine atom at the 6-position of indole ring or nitrogen atom at the 7-position of the indole ring resulted in lower antiviral activity. Most of the meridianin derivatives showed higher anti-TMV activities at 500 µg mL-1 than Ribavirin, especially for compounds 6c, 8a and 10a. All of the compounds also displayed broad spectrum fungicidal activities against 14 kinds of phytopathogenic fungi at 50 µg mL-1 . CONCLUSION: Compound 6c with relatively simple structure and excellent antiviral activity, which is similar to that of Ningnanmycin, emerged as novel anti-TMV lead compound. Compound 5d with broad spectrum and high effect fungicidal activity emerged as a new fungicidal lead compound. Current research lays a solid foundation for the application of meridianin alkaloids in crop protection. © 2019 Society of Chemical Industry.

Investigating reproductive success of the ladybird beetle Harmonia axyridis from the perspective of micropyle variation.

Micropyles in insects are small openings that allow sperm entry into, and the number was usually decreased on unfertilized and (or) undeveloped eggs. However, reports showed that Harmonia axyridis, a reproductive success model, deposited similar number of micropyles on undeveloped and developing eggs. Thus, it was confusing whether micropyles in H. axyridis were unaffected. To solve this confusion, two experiments were conducted here. Firstly, virgin female and four different days delayed mating (DDM) experiments were conducted to reveal the effects of fertilization stimulus and delayed-fertilization. Secondly, intercrosses between a light-colored mutant (HAM, an adaptive deficiency) and wild type (HAW) were conducted to further reveal whether there were female and male interactions. We found that (1) eggs produced by virgin and DDM females had significantly less micropyles than control. Even so, more than 18 micropyles were observed on eggs following fertilization and, consequently, egg production as well as hatch rate was not negatively affected by mating delay; (2) number of micropyles was significantly varied among the four reciprocal crosses and virgin HAW female. Specifically, the heterozygous eggs (Cross-D) and wild-type homozygous eggs (Cross-B) respectively had the least and maximum micropyles, and eggs from virgin HAW female had significantly less micropyles compared to those from HAW female (Cross-B or Cross-C), but the number was significantly higher than those from HAM female (Cross-A or Cross-D). These results informed us that the number of micropyles in H. axyridis is plastic but maintaining a high-quantity that offers many benefits, which should contribute to its reproduction success.

Glutathione triggered degradation of polydopamine to facilitate controlled drug release for synergic combinational cancer treatment.

Here we report a novel mechanism for triggering drug release in the polydopamine (PDA)-coated magnetic CuCo2S4 core-shell nanostructure by glutathione (GSH) triggered degradation of PDA for release. In the design, we used PDA coated CuCo2S4 as the nanocarrier with polyethylene glycol and folic acid targeting molecules to ensure the safe delivery of doxorubicin (DOX) to cancer cells. In addition, the controlled release could be enforced by taking advantage of the pH sensitivity of PDA to tumor acidic environments. The targeting and treatment of HeLa cancer cells were very effective and the killing was more efficient at higher levels of GSH. Furthermore, the designed system not only could be used for drug delivery but also could combine photothermal therapy with chemotherapy in a synergetic way. Plus, the system could be used for magnetic resonance imaging (MRI), which is beneficial for imaging-guided treatment.

Ti-Ti σ bond at oxygen vacancy inducing the deep defect level in anatase TiO2 (101) surface.

Using the GW method within many-body perturbation theory, we investigate the quasiparticle structures of defects, including oxygen vacancy, Ti interstitial, and hydroxyl groups, in the anatase TiO2 (101) surface. We find that the deep defect state in this surface observed experimentally, which is 1 eV below the Fermi level, originates from the σ bond formed between 3d orbitals of the two under-coordinated Ti atoms at the surface oxygen vacancy. Different from the density functional theory modified with on-site Coulomb terms (DFT + U), the GW method predicts that the localized polaron in anatase (101) is a shallow defect state close to the conduction band bottom. Polaronic states play the role in pinning the Fermi level of anatase near the conduction band bottom. Our GW calculations can explain satisfactorily the coexistence of shallow and deep defect states in anatase as observed in experiments. We also find that the conduction band edge of anatase is drawn down greatly after the filling of original empty Ti 3d orbitals by excess electrons, making the calculated bandgap of the reduced anatase agree well with the experiments. This significant difference in the bandgap between the intact and the reduced anatase is missed in DFT + U.

Functional morphology of the mouthparts of lady beetle Coccinella transversoguttata (Coccinellidae, Coleoptera), with reference to their feeding mechanism.

The lady beetle Coccinella transversoguttata is an important biocontrol agent of aphids. As the main the feeding apparatus, mouthparts play essential roles in feeding process, and the morphological variation of mouthparts is correlated with variation in food source and feeding behavior. To better understand the feeding behavior of C. transversoguttata, we studied the functional morphology of mouthparts, with special attention to the fine morphology of each part of mouthpart and various kinds of sensilla. The mouthpart of C. transversoguttata is typical mandibulate type that composed of labrum, mandible, maxillae, labium, and hypopharynx. Detailed descriptions were given about the fine morphology of each part, and various types of sensilla were identified and classified. In total, two types of sensilla chaetica, four types of sensilla basiconica, two types of sensilla styloconica, two types of sensilla placodea, and one type of cuticular pore were identified according to their length, morphology and distribution. Specially, the putative function of each part of mouthpart as well as each kind of sensilla and their coordinative mechanisms in feeding process were discussed. These results would lay a solid foundation for understanding the feeding mechanism of lady beetles.

Morphological and biological characterization of a light-colored mutant in the multicolored Asian lady beetle, Harmonia axyridis.

Insect cuticle color formed with melanin pigments has numerous types of mutants which usually cause pleiotropic effects. Melanism has been widely studied, but mutants with light-colored phenotype as well as the consequent fitness changes have rarely been reported.Here, in the laboratory strain of Harmonia axyridis, we found a novel mutant gr and confirmed that the mutation was inherited in a simple Mendelian autosomal recessive manner. This mutant (HAM) continuously displayed a light-colored pigmentation versus dark blackish in the wild phenotype (HAW). L-DOPA and dopamine are melanin precursors, and less L-DOPA was present in the cuticle of larval and adult HAM mutants compared to HAW wild type, but more dopamine was detected in the larval cuticle of HAM (p ≤ 0.0235). For the orange background of elytra, the composition as well as total concentration of carotenoids was different between HAM and HAW, which resulted in significantly lower saturation value but significantly higher hue value in HAM than in HAW (p < 0.0001).Extensive fitness changes were detected in HAM. (a) HAM larvae had similar predation capacity and preimaginal development time as HAW, but the newly emerged adults were much smaller (p < 0.0001). (b) Both fecundity and egg hatch rate in cross ♀(HAM) × â™‚(HAM) were significantly lower than those in ♀(HAW) × â™‚(HAW) (p ≤ 0.0087), but were not different with those in ♀(HAW) × â™‚(HAM).

A novel STAT3 inhibitor negatively modulates platelet activation and aggregation.

The signal transducer and activator of transcription 3 (STAT3) plays a critical role in platelet functions. This study sought to understand the effects of the STAT3 inhibitor SC99 on platelet activation and aggregation. Immunoblotting assays were applied to measure the effects of SC99 on the STAT3 signaling pathway. A ChronoLog aggregometer was used to evaluate platelet aggregation. A flow cytometer was used to evaluate P-selectin expression in the presence of SC99. AlamarBlue and Annexin-V staining were used to evaluate platelet viability and apoptosis, respectively. A fluorescence microscope was applied to analyze platelet spreading. SC99 inhibited the phosphorylation of JAK2 and STAT3 in human platelets but had no effects on the phosphorylation of AKT, p65 or Src, all of which are involved in platelet activation. Further studies revealed that SC99 inhibited human platelet aggregation induced by collagen and thrombin in a dose-dependent manner. SC99 inhibited thrombin-induced P-selectin expression and fibrinogen binding to single platelets. Moreover, SC99 inhibited platelet spreading on fibrinogen and clot retraction mediated by outside-in signaling. SC99 inhibited platelet aggregation in mice but it did not significantly prolong the bleeding time. Taken together, the present study revealed that SC99 inhibited platelet activation and aggregation as a STAT3 inhibitor. This agent can be developed as a promising treatment for thrombotic disorders.