Platelets favor the outgrowth of established metastases.

Despite abundant evidence demonstrating that platelets foster metastasis, anti-platelet agents have low therapeutic potential due to the risk of hemorrhages. In addition, whether platelets can regulate metastasis at the late stages of the disease remains unknown. In this study, we subject syngeneic models of metastasis to various thrombocytopenic regimes to show that platelets provide a biphasic contribution to metastasis. While potent intravascular binding of platelets to tumor cells efficiently promotes metastasis, platelets further support the outgrowth of established metastases via immune suppression. Genetic depletion and pharmacological targeting of the glycoprotein VI (GPVI) platelet-specific receptor in humanized mouse models efficiently reduce the growth of established metastases, independently of active platelet binding to tumor cells in the bloodstream. Our study demonstrates therapeutic efficacy when targeting animals bearing growing metastases. It further identifies GPVI as a molecular target whose inhibition can impair metastasis without inducing collateral hemostatic perturbations.

Assessment of platelet functional activity in healthy individuals and patients receiving antiplatelet therapy. Possible inconsistencies between aggregation and flow cytometry tests.

Platelet functional activity was assessed in healthy volunteers (HV, n=92), patients with stable angina pectoris (SA, n=42) and acute coronary syndrome (ACS, n=73), treated with acetylsalicylic acid (ASA) + clopidogrel and ASA + ticagrelor, respectively. In all HV and patients we have compared parameters of platelet aggregation (maximum light transmission and velocity, Tmax and Vmax) and parameters, characterizing exposure of platelet activation markers, evaluated by flow cytometry. HV platelets were activated by 10 µM, 1 µM TRAP, and 20 µM, 5 µM, 2.5 µM ADP; patient platelets were activated by 10 µM TRAP and by 20 µM and 5 µM ADP. Strong and significant correlations between the aggregation and flow cytometry parameters (the r correlation coefficient from 0.4 up to >0.6) most frequently were registered in HV platelet during activation by 1 µM TRAP and in SA patients during platelet activation by 20 µM and 5 µM ADP. However, in many other cases these correlations were rather weak (r < 0.3) and sometimes statistically insignificant. In HV the differences in PAC-1 binding parameters between platelets activated by 10 µM TRAP (the strongest agonist) and all ADP concentrations were negligible (≤ 10%), while CD62P binding (at all ADP concentrations) and LTA parameters for (5 µM and 2.5 µM ADP) were significantly lower (by 40-60%). Antiplatelet therapy in patients decreased all parameters as compared to HV, but to varying extents. For 10 µM TRAP the MFI index for PAC-1 binding (40-50% decrease) and for both ADP concentrations the Tmax values (60-85% decrease) appeared to be the most sensitive in comparison with the other parameters that decreased to a lesser extent. The data obtained indicate a possibility of inconsistency between different LTA and flow cytometry parameters in assessing platelet activity and efficacy of antiplatelet drugs.

Effect of Splenectomy on Coagulation and Platelet Function in Adult Liver Transplant Recipients Assessed With Rotational Thromboelastometry and Standard Coagulation Tests.

OBJECTIVES: Splenectomy during liver transplant can affect platelet function. In this study, our primary aim was to assess the perioperative platelet function by rotational thromboelastometry and the effects of splenectomy on platelet function. MATERIALS AND METHODS: We studied 40 consecutive liver transplant recipients with end-stage liver disease (50% as a result of hepatitis C). Patients with splenectomy were compared with patients without splenectomy (n = 20/group). Three platelet function parameters by rotational thromboelastometry were studied: platelet activation with arachidonic acid, platelet activation with adenosine diphosphate, and platelet activation with thrombin receptor-activating peptide 6. Patients were monitored perioperatively and until postoperative day 21. Heparin was infused for 2 days postoperatively (60-180 U/kg/day), followed by administration of subcutaneous low-molecular-weight heparin (40 mg/24 h) on postoperative days 2 and 3 and oral acetylsalicylic acid when platelet count was >50 × 103/µL. RESULTS: Liver disease contributed to low perioperative platelet count and function. Patients showed significant improvement by postoperative day 14 and day 21, particularly after splenectomy. Platelet count was significantly correlated with the 3 platelet function parameters by rotational thromboelastometry (P < .001). Acetyl salicylic acid was required earlier (postoperative day 3) for patients with splenectomy (8/20) but only affected the platelet function represented by platelet activation with arachidonic acid, whereas other platelet activation pathways were less affected. Patients received no transfusions of platelet units. CONCLUSIONS: End-stage liver disease significantly contributed to low platelet function and counts before transplant. Two weeks were required for recovery of patients posttransplant, with further enhancement by splenectomy. Some recipients showed recovery that exceeded the normal reference range, which warranted monitoring. Acetyl salicylic acid only affected 1 platelet activation receptor.

Effect of plateletcrit and methylenetetrahydrofolate reductase (MTHFR) C677T genotypes on folic acid efficacy in stroke prevention.

Previous studies have shown that low platelet count combined with high plasma total homocysteine (tHcy) increased stroke risk and can be lowered by 73% with folic acid. However, the combined role of other platelet activation parameters and the methylenetetrahydrofolate reductase (MTHFR) C677T genotypes on stroke risk and folic acid treatment benefit remain to be examined. This study aimed to investigate if platelet activation parameters and MTHFR genotypes jointly impact folic acid treatment efficacy in first stroke prevention. Data were derived from the China Stroke Primary Prevention Trial. This study includes a total of 11,185 adult hypertensive patients with relevant platelet activation parameters and MTHFR genotype data. When simultaneously considering both platelet activation parameters (plateletcrit, platelet count, mean platelet volume, platelet distribution width) and MTHFR genotypes, patients with both low plateletcrit (Q1) and the TT genotype had the highest stroke incidence rate (5.6%) in the enalapril group. This subgroup significantly benefited from folic acid treatment, with a 66% reduction in first stroke (HR: 0.34; 95% CI: 0.14-0.82; p = 0.016). Consistently, the subgroup with low plateletcrit (Q1) and the CC/CT genotype also benefited from folic acid treatment (HR: 0.40; 95% CI: 0.23-0.70; p = 0.001). In Chinese hypertensive adults, low plateletcrit can identify those who may greatly benefit from folic acid treatment, in particular, those with the TT genotype, a subpopulation known to have the highest stroke risk.

Antiplatelet Effects of Flavonoid Aglycones Are Mediated by Activation of Cyclic Nucleotide-Dependent Protein Kinases.

Flavonoid aglycones are secondary plant metabolites that exhibit a broad spectrum of pharmacological activities, including anti-inflammatory, antioxidant, anticancer, and antiplatelet effects. However, the precise molecular mechanisms underlying their inhibitory effect on platelet activation remain poorly understood. In this study, we applied flow cytometry to analyze the effects of six flavonoid aglycones (luteolin, myricetin, quercetin, eriodictyol, kaempferol, and apigenin) on platelet activation, phosphatidylserine externalization, formation of reactive oxygen species, and intracellular esterase activity. We found that these compounds significantly inhibit thrombin-induced platelet activation and decrease formation of reactive oxygen species in activated platelets. The tested aglycones did not affect platelet viability, apoptosis induction, or procoagulant platelet formation. Notably, luteolin, myricetin, quercetin, and apigenin increased thrombin-induced thromboxane synthase activity, which was analyzed by a spectrofluorimetric method. Our results obtained from Western blot analysis and liquid chromatography-tandem mass spectrometry demonstrated that the antiplatelet properties of the studied phytochemicals are mediated by activation of cyclic nucleotide-dependent signaling pathways. Specifically, we established by using Förster resonance energy transfer that the molecular mechanisms are, at least partly, associated with the inhibition of phosphodiesterases 2 and/or 5. These findings underscore the therapeutic potential of flavonoid aglycones for clinical application as antiplatelet agents.

Cisplatin-loaded mesoporous polydopamine nanoparticles capped with MnO2 and coated with platelet membrane provide synergistic anti-tumor therapy.

A multifunctional nanoplatform was constructed in this work, with the goal of ameliorating the challenges faced with traditional cancer chemotherapy. Cisplatin (CP) was loaded into mesoporous polydopamine (mPDA) nanoparticles (NPs) with a drug loading of 15.8 ± 0.1 %, and MnO2 used as pore sealing agent. Finally, the NPs were wrapped with platelet membrane (PLTM). P-selectin on the PLTM can bind to CD44, which is highly expressed on the tumor cell membrane, so as to improve the targeting performance of the NPs. In addition, the CD47 on the PLTM can prevent the NPs from being phagocytosed by macrophages, which is conducive to immune escape. The final PLTM-CP@mPDA/MnO2 NPs were found to have a particle size of approximately 198 nm. MnO2 is degraded into Mn2+ in the tumor microenvironment, leading to CP release from the pores in the mPDA. CP both acts as a chemotherapy agent and can also increase the concentration of H2O2 in cells. Mn2+ can catalyze the conversion of H2O2 to OH, resulting in oxidative damage and chemodynamic therapy. In addition, Mn2+ can be used as a contrast agent in magnetic resonance imaging (MRI). In vitro and in vivo experiments were performed to explore the therapeutic effect of the NPs. When the concentration of CP is 30 µg/mL, the NPs cause approximately 50 % cell death. It was found that the PLTM-CP@mPDA/MnO2 NPs are targeted to cancerous cells, and in the tumor site cause extensive apoptosis. Tumor growth is thereby repressed. No negative off-target side effects were noted. MRI could be used to confirm the presence of the NPs in the tumor site. Overall, the nano-platform developed here provides cooperative chemotherapy and chemodynamic therapy, and can potentially be used for effective cancer treatment which could be monitored by MRI.

Oxidative Stress-Induced Platelet Apoptosis/Activation: Alleviation by Purified Curcumin via ASK1-JNK/p-38 Pathway.

Platelets are known for their indispensable role in hemostasis and thrombosis. However, alteration in platelet function due to oxidative stress is known to mediate various health complications, including cardiovascular diseases and other health complications. To date, several synthetic molecules have displayed antiplatelet activity; however, their uses are associated with bleeding and other adverse effects. The commercially available curcumin is generally a mixture of three curcuminoids: curcumin, demethoxycurcumin, and bisdemethoxycurcumin. Although crude curcumin is known to inhibit platelet aggregation, the effect of purified curcumin on platelet apoptosis, activation, and aggregation remains unclear. Therefore, in this study, curcumin was purified from a crude curcumin mixture and the effects of this preparation on the oxidative stress-induced platelet apoptosis and activation was evaluated. 2,2'-Azobis(2-methylpropionamidine) dihydrochloride (AAPH) compound was used as an inducer of oxidative stress. Purified curcumin restored AAPH-induced platelet apoptotic markers like reactive oxygen species, intracellular calcium level, mitochondrial membrane potential, cardiolipin peroxidation, cytochrome c release from mitochondria to the cytosol, and phosphatidyl serine externalization. Further, it inhibited the agonist-induced platelet activation and aggregation, demonstrating its antiplatelet activity. Western blot analysis confirms protective effect of the purified curcumin against oxidative stress-induced platelet apoptosis and activation via downregulation of MAPKs protein activation, including ASK1, JNK, and p-38. Together, these results suggest that the purified curcumin could be a potential therapeutic bioactive molecule to treat the oxidative stress-induced platelet activation, apoptosis, and associated complications.

Eltrombopag can promote platelet implantation after allogeneic hematopoietic stem cell transplantation as safely and similarly to thrombopoietin.

Background: Eltrombopag has demonstrated efficacy in treating low platelet (PLT) levels, but it remains unclear whether eltrombopag can promote PLT engraftment after hematopoietic stem cell transplantation (HSCT). Methods: Forty-one HSCT patients received eltrombopag 50 mg/d from +1 day until PLT >50 × 109/L or 1 month after HSCT. Fifty-one patients in the same period received thrombopoietin (TPO) to promote PLT graft after HSCT and served as a control group. Results: A total of 51 patients who applied TPO during the same period were treated as a control. In the eltrombopag group, the median time to white blood cells (WBC) graft was 12 days (range, 10-17 days) and the PLT graft was 15 days (range, 10-30 days), whereas for the patients in the TPO group, the median time to WBC and PLT graft was 12 days (range, 9-23 days) and 15.5 days (range, 9-41 days), respectively. In the first month after HSCT, the median WBC count in the eltrombopag group was 4.41 × 109/L (range, 0.87-40.01 × 109/L) and the median PLT was 89x109/L (range, 30-401 × 109/L); the median WBC and PLT \counts in the TPO group were 4.65 × 109/L (range, 0.99-23.63 × 109/L) and 86 × 109/L (range, 5-512 × 109/L), respectively. Patients in the TPO or eltrombopag group did not experience serious side effects after drug administration, and the difference in side effects on liver and kidney function between the two groups was not statistically significant. Conclusion: Eltrombopag is safe and similarly promotes platelet engraftment to thrombopoietin after allogeneic HSCT.

Genetically encoded biocompatible anti-coagulant protein-coated coronary artery stents drive endothelialization.

In response to the critical demand for advancements in coronary artery stents, this study addresses the challenges associated with arterial recoil and restenosis post-angioplasty and the imperative to encourage rapid re-endothelialization for minimizing thrombosis risks. We employed an innovative approach inspired by mussel adhesion, incorporating placental anticoagulant protein (AnnexinV) on stent design. The introduction of a post-translationally modified catecholic amino acid L-3,4-dihydroxyphenylalanine (L-Dopa), mimicking mussel characteristics, allowed for effective surface modification of Stainless steel stents through genetic code engineering in AnnexinV (AnxDopa). The efficacy of AnxDopa was analyzed through microscale thermophoresis and flow cytometry, confirming AnxDopa's exceptional binding with phosphatidylserine and activated platelets. AnxDopa coated stainless steel demonstrates remarkable bio-, hemo-, and immuno-compatibility, preventing smooth muscle cell proliferation, platelet adhesion, and fibrin formation. It acts as an interface between the stent and biological fluid, which facilitates the anticoagulation and rapid endothelialization. Surface modification of SS verified through XPS analysis and contact angle measurement attests to the efficacy of AnxDopa mediated surface modification. The hydrophilic nature of the AnxDopa-coated surface enhanced the endothelialization through increased protein absorption. This approach represents a significant stride in developing coronary stents with improved biocompatibility and reduced restenosis risks, offering valuable contributions to scientific and clinical realms alike.

Individualized antiplatelet therapy for non-cardiogenic ischemic stroke.

OBJECTIVE: This research aims to investigate the impact of individualized antiplatelet therapy guided by thromboelastography with platelet mapping (TEG-PM) on the clinical outcomes of patients with non-cardiogenic ischemic stroke. METHODS: Among a total of 1264 patients, 684 individuals diagnosed with non-cardiogenic ischemic stroke underwent TEG-PM testing. Based on the adjustment of antiplatelet medication, these patients were divided into individual and control groups. Within the individual group, in accordance with the TEG-PM test results, a Maximum amplitude (MA) value greater than 47mm was defined as high residual platelet reactivity (HRPR), while an MA value less than 31mm was defined as low residual platelet reactivity (LRPR). Patients with arachidonic acid (AA) less than 50% and adenosine diphosphate (ADP) less than 30% were classified as aspirin-resistant or clopidogrel-resistant. Treatment strategies for antiplatelet medication were subsequently adjusted accordingly, encompassing increment, decrement, or replacement of drugs. Meanwhile, the control group maintained their original medication regimen without alterations. RESULTS: The individual group included 487 patients, while the control group had 197. In the individual group, approximately 175 patients (35.9%) were treated with increased medication dosages, 89 patients (18.3%) with reduced dosages, and 223 patients (45.8%) switched medications. The results showed that the incidence rate of ischemic events in the individual group was lower than that of the control group (5.54% vs. 12.6%, P = 0.001), but no significant difference was observed in bleeding events. Cox regression analysis revealed age (hazard ratio, 1.043; 95% CI, 1.01-1.078; P = 0.011) and coronary heart disease (hazard ratio, 1.902; 95% CI, 1.147-3.153; P = 0.013) as significant risk factors for adverse events. CONCLUSION: Individualized antiplatelet therapy based on TEG-PM results can reduce the risk of ischemic events in patients with non-cardiogenic ischemic stroke without increasing the risk of bleeding events or mortality. Advanced age and coronary heart disease were identified as risk factors affecting the outcomes of individualized antiplatelet therapy.

Qilong capsule prevents myocardial ischemia/reperfusion injury by inhibiting platelet activation via the platelet CD36 signaling pathway.

ETHNOPHARMACOLOGICAL RELEVANCE: Qilong capsule (QC) is developed from the traditional Chinese medicine formula Buyang Huanwu Decoction, which has been clinically used to invigorate Qi and promote blood circulation to eliminate blood stasis. Myocardial ischemia‒reperfusion injury (MIRI) can be attributed to Qi deficiency and blood stasis. However, the effects of QC on MIRI remain unclear. AIM OF THE STUDY: This study aimed to investigate the protective effect and possible mechanism of QC on platelet function in MIRI rats. MATERIALS AND METHODS: The left anterior descending artery of adult Sprague‒Dawley rats was ligated for 30 min and then reperfused for 120 min with or without QC treatment. Then, the whole blood viscosity, plasma viscosity, coagulation, platelet adhesion rate, platelet aggregation, and platelet release factors were evaluated. Platelet CD36 and its downstream signaling pathway-related proteins were detected by western blotting. Furthermore, the active components of QC and the molecular mechanism by which QC regulates platelet function were assessed via molecular docking, platelet aggregation tests in vitro and BLI analysis. RESULTS: We found that QC significantly reduced the whole blood viscosity, plasma viscosity, platelet adhesion rate, and platelet aggregation induced by ADP or AA in rats with MIRI. The inhibition of platelet activation by QC was associated with reduced levels of ß-TG, PF-4, P-selectin and PAF. Mechanistically, QC effectively attenuated the expression of platelet CD36 and thus inhibited the activation of Src, ERK5, and p38. The active components of QC apparently suppressed platelet aggregation in vitro and regulated the CD36 signaling pathway. CONCLUSIONS: QC improves MIRI-induced hemorheological disorders, which might be partly attributed to the inhibition of platelet activation via CD36-mediated platelet signaling pathways.

Linking triphenylphosphonium cation to a bicyclic hydroquinone improves their antiplatelet effect via the regulation of mitochondrial function.

Platelets are the critical target for preventing and treating pathological thrombus formation. However, despite current antiplatelet therapy, cardiovascular mortality remains high, and cardiovascular events continue in prescribed patients. In this study, first results were obtained with ortho-carbonyl hydroquinones as antiplatelet agents; we found that linking triphenylphosphonium cation to a bicyclic ortho-carbonyl hydroquinone moiety by a short alkyl chain significantly improved their antiplatelet effect by affecting the mitochondrial functioning. The mechanism of action involves uncoupling OXPHOS, which leads to an increase in mitochondrial ROS production and a decrease in the mitochondrial membrane potential and OCR. This alteration disrupts the energy production by mitochondrial function necessary for the platelet activation process. These effects are responsive to the complete structure of the compounds and not to isolated parts of the compounds tested. The results obtained in this research can be used as the basis for developing new antiplatelet agents that target mitochondria.

Apolipoprotein A-IV polymorphisms Q360H and T347S attenuate its endogenous inhibition of thrombosis.

Platelets are small anucleate cells that play a key role in thrombosis and hemostasis. Our group previously identified apolipoprotein A-IV (apoA-IV) as an endogenous inhibitor of thrombosis by competitive blockade of the αIIbß3 integrin on platelets. ApoA-IV inhibition of platelets was dependent on the N-terminal D5/D13 residues, and enhanced with absence of the C-terminus, suggesting it sterically hinders its N-terminal platelet binding site. The C-terminus is also the site of common apoA-IV polymorphisms apoA-IV-1a (T347S) and apoA-IV-2 (Q360H). Interestingly, both are linked with an increased risk of cardiovascular disease, however, the underlying mechanism remains unclear. Here, we generated recombinant apoA-IV and found that the Q360H or T347S polymorphisms dampened its inhibition of platelet aggregation in human platelet-rich plasma and gel-filtered platelets, reduced its inhibition of platelet spreading, and its inhibition of P-selectin on activated platelets. Using an ex vivo thrombosis assay, we found that Q360H and T347S attenuated its inhibition of thrombosis at both high (1800s-1) and low (300s-1) shear rates. We then demonstrate a conserved monomer-dimer distribution among apoA-IV WT, Q360H, and T347S and use protein structure modelling software to show Q360H and T347S enhance C-terminal steric hindrance over the N-terminal platelet-binding site. These data provide critical insight into increased cardiovascular risk for individuals with Q360H or T347S polymorphisms.

Platelet Membrane-Coated r-SAK Improves Thrombolytic Efficacy by Targeting Thrombus.

Thrombolytic therapy is one of the most effective treatments for thrombus dissolution and recanalization of blocked vessels in thrombotic diseases. However, the application of the thrombolytic strategy has been limited due to unsatisfactory thrombolytic efficacy, relatively higher bleeding complications, and consequently restricted indications. Recombinant staphylokinase (r-SAK) is a third-generation thrombolytic agent produced by genetic engineering technology, which exhibits a better thrombolytic efficacy than urokinase and recombinant streptokinase. Inspired by the natural affinity of platelets in hemostasis and pathological thrombosis, we developed a platelet membrane (PM)-coated r-SAK (PM-r-SAK). Results from animal experiments and human in vitro studies showed that the PM-r-SAK had a thrombolytic efficacy equal to or better than its 4-fold dose of r-SAK. In a totally occluded rabbit femoral artery thrombosis model, the PM-r-SAK significantly shortened the initial recanalization time compared to the same dose and 4-fold dose of r-SAK. Regarding the recanalized vessels, the PM-r-SAK prolonged the time of reperfusion compared to the same dose and 4-fold dose of r-SAK, though the differences were not significant. An in vitro thrombolytic experiment demonstrated that the thrombolytic efficacy of PM-r-SAK could be inhibited by platelet-poor plasma from patients taking aspirin and ticagrelor. PM coating significantly improves the thrombolytic efficacy of r-SAK, which is related to the thrombus-targeting activity of the PM-r-SAK and can be inhibited by aspirin- and ticagrelor-treated plasma.

Dietary n-3 polyunsaturated fatty acids alter the number, fatty acid profile and coagulatory activity of circulating and platelet-derived extracellular vesicles: a randomized, controlled crossover trial.

BACKGROUND: Extracellular vesicles (EVs) are proposed to play a role in the development of cardiovascular diseases (CVDs) and are considered emerging markers of CVDs. n-3 PUFAs are abundant in oily fish and fish oil and are reported to reduce CVD risk, but there has been little research to date examining the effects of n-3 PUFAs on the generation and function of EVs. OBJECTIVES: We aimed to investigate the effects of fish oil supplementation on the number, generation, and function of EVs in subjects with moderate risk of CVDs. METHODS: A total of 40 participants with moderate risk of CVDs were supplemented with capsules containing either fish oil (1.9 g/d n-3 PUFAs) or control oil (high-oleic safflower oil) for 12 wk in a randomized, double-blind, placebo-controlled crossover intervention study. The effects of fish oil supplementation on conventional CVD and thrombogenic risk markers were measured, along with the number and fatty acid composition of circulating and platelet-derived EVs (PDEVs). PDEV proteome profiles were evaluated, and their impact on coagulation was assessed using assays including fibrin clot formation, thrombin generation, fibrinolysis, and ex vivo thrombus formation. RESULTS: n-3 PUFAs decreased the numbers of circulating EVs by 27%, doubled their n-3 PUFA content, and reduced their capacity to support thrombin generation by >20% in subjects at moderate risk of CVDs. EVs derived from n-3 PUFA-enriched platelets in vitro also resulted in lower thrombin generation, but did not alter thrombus formation in a whole blood ex vivo assay. CONCLUSIONS: Dietary n-3 PUFAs alter the number, composition, and function of EVs, reducing their coagulatory activity. This study provides clear evidence that EVs support thrombin generation and that this EV-dependent thrombin generation is reduced by n-3 PUFAs, which has implications for prevention and treatment of thrombosis. CLINICAL TRIAL REGISTRY: This trial was registered at clinicaltrials.gov as NCT03203512.

Recombinant Human Thrombopoietin Promotes Platelet Engraftment in Severe Aplastic Anemia Patients Following Treatment With Haploid Hematopoietic Stem Cell Transplantation using Modified Post-Transplantation Cyclophosphamide.

BACKGROUND: Recombinant human TPO (rhTPO) promotes platelet engraftment in patients after allogeneic HSCT (allo-HSCT). However, the effects of rhTPO on platelet recovery after Haplo-HSCT in patients with severe aplastic anemia (SAA) have not been intensively studied. OBJECTIVE: We aimed to evaluate the efficacy of rhTPO on platelet engraftment in patients with SAA who were treated with Haplo-HSCT using post-transplantation cyclophosphamide (PTCy). STUDY DESIGN: SAA patients who received Haplo-HSCT plus PTCy regimen were divided into the rhTPO group (with subcutaneous injection of rhTPO, n = 28) and Control group (no rhTPO administration, n = 27). The engraftment of platelet/neutrophil, platelet infusion amount, and transplant-related complications between the 2 groups were compared. RESULTS: All 55 patients showed successful hematopoietic reconstitution. The median time of platelet engraftment was 11 (9 to 29) days in the rhTPO group and 14 (9 to 28) days in the Control group (P = .003). The rhTPO group had a significantly reduced amount of infused platelets compared to the Control group (2 (1 to 11.5) versus 3 (1 to 14) therapeutic doses; P = .004). There was no significant difference between the 2 groups regarding median time of neutrophil engraftment, incidence of acute graft-versus-host disease (aGVHD) and chronic GVHD (cGVHD), incidence of cytomegalovirus or Epstein-Barr virus reactivation, 3-yr overall survival rate, and failure-free-survival rate. No obvious adverse reactions were observed in the rhTPO group. CONCLUSION: rhTPO promoted platelet engraftment, reduced the amount of transfused platelets, and demonstrated good safety profiles without evidence of adverse reactions in patients with SAA who received Haplo-HSCT using PTCy regimen.

Engineering unactivated platelets for targeted drug delivery.

As a vital component of blood, platelets play crucial roles in hemostasis and maintaining vascular integrity, and actively participate in inflammation and immune regulation. The unique biological properties of natural platelets have enabled their utilization as drug delivery vehicles. The advancement and integration of various techniques, including biological, chemical, and physicochemical methods, have enabled the preparation of engineered platelets. Platelets can serve as drug delivery platforms combined with immunotherapy and chemokine therapy to enhance their therapeutic impact. This review focuses on the recent advancements in the application of unactivated platelets for drug delivery. The construction strategies of engineered platelets are comprehensively summarized, encompassing internal loading, surface modification, and genetic engineering techniques. Engineered platelets hold vast potential for treating cardiovascular diseases, cancers, and infectious diseases. Furthermore, the challenges and potential considerations in creating engineered platelets with natural activity are discussed.

Ethyl-acetate extract of Spatholobi Caulis blocked the pro-metastatic support from the hemato-microenvironment of colon cancer by specific disruption of tumor-platelet adhesion.

BACKGROUND: Within the pro-metastatic hemato-microenvironment, interaction between platelets and tumor cells provides essential support for tumor cells by inducing Epithelial-Mesenchymal Transition (EMT), which greatly increases the stemness of colon cancer cells. Pharmacologically, although platelet deactivation has proved to be benefit against metastasis, its wide application is severely restricted due to the bleeding risk. Spatholobi Caulis, a traditional Chinese herb with circulatory promotion and blood stasis removal activity, has been proved to be clinically effective in malignant medication, leaving its mechanistic relevance to tumor-platelet interaction largely unknown. METHODS: Firstly, MC38-Luc cells were injected into tail-vein in C57BL/6 mice to establish hematogenous metastasis model and the anti-metastasis effects of SEA were evaluated by using a small-animal imaging system. Then, we evaluated the anti-tumor-platelet interaction efficacy of SEA using a tumor-specific induced platelet aggregation model. Platelet aggregation was specifically induced by tumor cells in vitro. Furthermore, to clarify the anti-metastatic effects of SEA is mainly attributed to its blockage on tumor-platelet interaction, after co-culture with tumor cells and platelets (with or without SEA), MC38-Luc cells were injected into the tail-vein and finally count the total of photons quantitatively. Besides, to clarify the blocking pattern of SEA within the tumor-platelet complex, the dependence of SEA on different fractions from activated platelets was tested. Lastly, molecular docking screening were performed to screen potential effective compounds and we used ß-catenin blockers to verify the pathways involved in SEA blocking tumor-platelet interaction. RESULTS: Our study showed that SEA was effective in blocking tumor-platelet specific interaction: (1) Through CCK-8 and LDH assays, SEA showed no cytotoxic effects on tumor cells and platelets. On this basis, by the tail vein injection model, the photon counts in the SEA group was significantly lower than model group, indicating that SEA effectively reduced metastasis. (2) In the "tumor-platelet" co-culture model, SEA effectively inhibited the progression of EMT and cancer stemness signatures of MC38 cells in the model group. (3) In mechanism study, by using the specific inhibitors for galectin-3 (GB1107) andWNT (IWR) respectively, we proved that SEA inhibits the activation of the galectin-3-mediated ß-catenin activation. CONCLUSION: By highlighting the pro-metastatic effects of galectin-3-mediated tumor-platelet adhesion, our study provided indicative evidence for Spatholobi Caulis as the representative candidate for anti-metastatic therapy.