Cyclic Stretch Induces Adhesion of VSMCs with Platelet-Derived Microparticles and the Role in Autophagy / 医用生物力学

Objective To investigate the effect of cyclic stretch on adhesion of vascular smooth muscle cells (VSMCs) with platelet-derived microparticles (PMPs), and the role of PMPs in VSMC autophagy. Methods Cyclic stretch with the magnitude of 5% (simulating physiological mechanical stretch) or 15% (simulating pathological mechanical stretch) was subjected to VSMCs in vitro by using FX-5000T cyclic stretch loading system, and the adhesion of PMPs in VSMCs was detected by using flow cytometry. Immunofluorescence was used to detect the expression of autophagy microtubule associated protein light chain 3 (LC3) after 24 h stimulation with PMPs. Western blotting was used to detect the expression of autophagy related protein (Atg) in VSMCs after 24 h stimulation by PMPs. Results Compared with 5% cyclic stretch, 15% cyclic stretch significantly increased the adhesion ability of VSMCs with PMPs. Immunofluorescence and Western blotting result revealed that PMPs stimulation significantly increased the expression of autophagy marker protein LC3 in VSMCs. Furthermore, the protein expressions of Atg5, Atg7 and Atg12 were all significantly increased in VSMCs stimulated with PMPs. Conclusions High cyclic stretch may enhance the autophagy of VSMCs by promoting the adhesion of PMPs, which will subsequently increase the expressions of Atg5, Atg7, Atg12 and LC3.

Increased levels of reactive oxygen species in platelets and platelet-derived microparticles and the risk of respiratory failure in HIV/AIDS patients

Respiratory failure (RF) is the main cause of hospital admission in HIV/AIDS patients. This study assessed comorbidities and laboratory parameters in HIV/AIDS inpatients with RF (N = 58) in relation to those without RF (N = 36). Tuberculosis showed a huge relative risk and platelet counts were slightly higher in HIV/AIDS inpatients with RF. A flow cytometry assay for reactive oxygen species (ROS) showed lower levels in platelets of these patients in relation to the healthy subjects. However, when stimulated with adrenaline, ROS levels increased in platelets and platelet-derived microparticles of HIV/AIDS inpatients, which may increase the risk of RF during HIV and tuberculosis (HIV-TB) coinfection.

The Usefulness of Platelet-derived Microparticle as Biomarker of Antiplatelet Therapy in Kawasaki Disease

Little is known about platelet dynamics and the effect of antiplatelet therapy in Kawasaki disease (KD). This study sought to define platelet activation dynamics in KD patients by assaying platelet-derived microparticles (PDMPs). We measured plasma PDMPs levels in 46 patients with KD using an enzyme-linked immunosorbent assay (ELISA). Blood samples were collected before, at 2–5 days, and 9–15 days after intravenous immunoglobulin (IVIG) infusion, 2 months and 4–5 months after the onset of KD. We measured PDMP levels in 23 febrile and 10 afebrile control patients. In the acute phase of KD patients, PDMP levels increased significantly after IVIG treatment (12.04 ± 5.58 nmol before IVIG infusion vs. 19.81 ± 13.21 nmol at 2–5 days after IVIG infusion, P = 0.006). PDMP levels were negatively correlated with age and positively correlated with procalcitonin levels in the acute phase of KD. No significant difference was found in PDMP levels between KD patients with and without coronary artery lesion (CAL). Elevated PDMP levels after IVIG therapy significantly decreased below the pre-IVIG level in subacute phase (19.81 ± 13.21 nmol at 2–5 days after IVIG infusion vs. 8.33 ± 2.02 nmol at 9–15 days after IVIG infusion, P < 0.001), and PDMP levels stayed below the pre-IVIG level in the convalescent phase, during which antiplatelet therapy was given. However, PDMP levels rebounded after discontinuing aspirin in 17 patients. In conclusion, enhanced platelet activation was noted before treatment of KD and peaked immediately after IVIG treatment. Recurrent rising of PDMP levels was observed after discontinuing aspirin, although there were no significant differences between the PDMP levels at 2 months after the onset of KD and those at 4–5 months after the onset of the disease.

Damage mechanism on vascular endothelium by platelet-derived microparticle / 国际儿科学杂志

Platelet-derived microparticle (PMP)is a heterogeneous vesicle (＜ 1 μm)generated from the plasma membrane when platelets are activated by various stimulation,which is composed of serous cystic fragments and α-granules.The formation,release and level of circulating PMP can reflect the platelet activation.The functions of PMP include facilitating coagulation,promoting adhesion of platelet and leukocyte to the subendothelial membrane,promoting angiogenesis and stimulating the proliferation of vascular smooth muscle.High level of PMP appears in many cardiovascular diseases such as atherosclerosis,diabetes mellitus,Kawasaki disease and so on.This paper is to review the mechanism of PMP in the vascular endothelial injury.