Antiplatelet Agents Inhibit Platelet Adhesion and Aggregation on Glass Surface Under Physiological Flow Conditions: Toward a Microfluidic Platelet Functional Assay Without Additional Adhesion Protein Modification.

ABSTRACT: As the pathogenesis of arterial thrombosis often includes platelet adhesion and aggregation, antiplatelet agents are commonly used to prevent thromboembolic events. Here, a new microfluidic method without additional adhesion protein modification was developed to quantify the inhibitory effect of antiplatelet drugs on the adhesion and aggregation behavior of platelets on glass surfaces under physiological flow conditions. Polydimethylsiloxane-glass microfluidic chips were fabricated by soft photolithography. Blood samples from healthy volunteers or patients before and after taking antiplatelet drugs flowed through the microchannels at wall shear rates of 300 and 1500 second -1 , respectively. The time to reach 2.5% platelet aggregation surface coverage (Ti), surface coverage (A 150s ), and mean fluorescence intensity (F 150s ) were used as quantitative indicators. Aspirin (80 µM) prolonged Ti and reduced F 150s . Alprostadil, ticagrelor, eptifibatide, and tirofiban prolonged Ti and reduced A 150s and F 150s in a concentration-dependent manner, whereas high concentrations of alprostadil did not completely inhibit platelet aggregation. Aspirin combined with ticagrelor synergistically inhibited platelet adhesion and aggregation; GPIb-IX-von Willebrand factor inhibitors partially inhibited platelet aggregation, and the inhibition was more pronounced at 1500 than at 300 second -1 . Patient administration of aspirin or (and) clopidogrel inhibited platelet adhesion and aggregation on the glass surface under flow conditions. This technology is capable of distinguishing the pharmacological effects of various antiplatelet drugs on inhibition of platelet adhesion aggregation on glass surface under physiological flow conditions, which providing a new way to develop microfluidic platelet function detection method without additional adhesive protein modification for determining the inhibitory effects of antiplatelet drugs in the clinical setting.

Antibody responses to SARS-CoV-2 Omicron infection in patients with hematological malignancies: A multicenter, prospective cohort study.

Little is known about antibody responses to natural Omicron infection and the risk factors for poor responders in patients with hematological malignancies (HM). We conducted a multicenter, prospective cohort study during the latest Omicron wave in Chongqing, China, aiming to compare the antibody responses, as assessed by IgG levels of anti-receptor binding domain of spike protein (anti-S-RBD), to Omicron infection in the HM cohort (HMC) with healthy control cohort (HCC), and solid cancer cohort (SCC). In addition, we intend to explore the risk factors for poor responders in the HMC. Among the 466 HM patients in this cohort, the seroconversion rate was 92.7%, no statistically difference compared with HCC (98.2%, p = 0.0513) or SCC (100%, p = 0.1363). The median anti-S-RBD IgG titer was 29.9 ng/mL, significantly lower than that of HCC (46.9 ng/mL, p < 0.0001) or SCC (46.2 ng/mL, p < 0.0001). Risk factors associated with nonseroconversion included no COVID-19 vaccination history (odds ratio [OR] = 4.58, 95% confidence interval [CI]: 1.75-12.00, p = 0.002), clinical course of COVID-19 ≤ 7 days (OR = 2.86, 95% CI: 1.31-6.25, p = 0.008) and severe B-cell reduction (0-10/µL) (OR = 3.22, 95% CI: 1.32-7.88, p = 0.010). Risk factors associated with low anti-S-RBD IgG titer were clinical course of COVID-19 ≤ 7 days (OR = 2.58, 95% CI: 1.59-4.18, p < 0.001) and severe B-cell reduction (0-10/µL) (OR = 2.87, 95% CI: 1.57-5.24, p < 0.001). This study reveals a poor antibody responses to Omicron (BA.5.2.48) infection in HM patients and identified risk factors for poor responders. Highlights that HM patients, especially those with these risk factors, may be susceptible to SARS-CoV-2 reinfection, and the postinfection vaccination strategies for these patients should be tailored. Clinical trial: ChiCTR2300071830.

[Effect and mechanism of matrine on apoptosis of Raji cells].

OBJECTIVE: To invest the effect and mechanism of matrine on apoptosis of human Burkitt's lymphoma Raji cells. METHODS: Raji cells were cultured in vitro and treated by different final concentrations (0.4, 0.8, 1.6 mg/mL) of matrine or combined with SB203580 (p38 MAPK inhibitor) before matrine was added, then cocultured for 48 h, cell apoptosis rate was detected by Annexin V-FITC/PI double staining method and the P-p38 MAPK, Fas, FasL protein expresssion of Raji cells were evaluated by Western blot. RESULTS: After cells were treated by matrine (0.4, 0.8, 1.6 mg/mL), the corresponding total apoptosis rate (15.77 +/- 0.53)%, (27.88 +/- 1.52)%, (48.08 +/- 2.87)%, had statistical significance compared with SB203580 groups (11. 48 +/- 0.64)%, (19.34 +/- 0.91)%, (33.98 +/- 1.26)% (P < 0.05 or P < 0.01), and control group (8.78 +/- 0.66)% (P < 0.05 or P < 0.01). As the concentration of matrine gradually increased,the protein expresssion levels of P-p38MAPK, Fas, FasL increased, and decreased after SB203580 were added, the correlation of P-p38MAPK and Fas, FasL was obvious. CONCLUSION: Matrine can upregulation of Fas and FasL to promote the apoptosis of Raji cells, it may be related to p38MAPK Activation.

Immune thrombocytopenia induces autophagy and suppresses apoptosis in megakaryocytes.

Immune thrombocytopenia (ITP) is the main pathogenesis of excessive platelet destruction and abnormal megakaryocyte apoptosis, however, the mechanism underlying this abnormality in megakaryocytes remains to be elucidated. Since autophagy and apoptosis are closely interrelated, it can be speculated that the abnormal apoptosis of ITP megakaryocytes is associated with autophagy. To test this hypothesis, a total of 14 patients with ITP and 23 healthy controls were recruited. MEG­01 cell line was cultured in vitro, and morphological changes were observed by light microscopy, apoptosis was evaluated by flow cytometric analysis of Annexin V­FITC/propidium iodide staining and western blot analysis of B­cell lymphoma (Bcl)­2, Bcl­associated X protein (Bax), Beclin­1 and cleaved caspase 3. Apoptotic abnormalities and autophagy were observed in the ITP plasma group. Furthermore, Bax expression was downregulated, while Beclin­1 was upregulated. Chloroquine can block autophagy induced by ITP and remove the ITP plasma inhibition of apoptosis. Therefore, it may be concluded that ITP may induce autophagy, the inhibition of which may be a novel treatment for ITP.