Platelet clearance has already been studied in physiological and pathological conditions and shown its occurrence mainly in the liver and the spleen. It is still not clear what mechanisms are responsible for recognition and removal of either aged or damaged platelets by the scavenging system. So study of the clearance mechanism will be useful to prolong the survival time of platelets in vivo. And it may be related to a new strategy to store platelets. This article focuses on the advances in studies of the clearance mechanism of transfused platelet concentrates, including roles of P-selectin, GPI balpha and its receptor Mac-1 in platelet clearance, and effect of endogenous metalloproteinase in platelet clearance.
Blood Platelets ; physiology ; Blood Preservation ; Cellular Senescence ; Humans ; Macrophage-1 Antigen ; physiology ; Metalloproteases ; physiology ; P-Selectin ; physiology ; Platelet Activation ; Platelet Glycoprotein GPIb-IX Complex ; physiology ; Platelet Transfusion

Tissue plasminogen activator (tPA) is the only therapeutic agent approved to treat patients with acute ischemic stroke. The clinical benefits of tPA manifest when the agent is administered within 4.5 hours of stroke onset. However, tPA administration, especially delayed administration, is associated with increased intracranial hemorrhage (ICH), hemorrhagic transformation (HT), and mortality. In the ischemic brain, vascular remodeling factors are upregulated and microvascular structures are destabilized. These factors disrupt the blood brain barrier (BBB). Delayed recanalization of the vessels in the presence of relatively matured infarction appears to damage the BBB, resulting in HT or ICH, also known as reperfusion injury. Moreover, tPA itself activates matrix metalloproteases, further aggravating BBB disruption. Therefore, attenuation of edema, HT, or ICH after tPA treatment is an important therapeutic strategy that may enable clinicians to extend therapeutic time and increase the probability of excellent outcomes. Recently, numerous agents with various mechanisms have been developed to interfere with various steps of ischemia/reperfusion injuries or BBB destabilization. These agents successfully reduce infarct volume and decrease the incidence of ICH and HT after delayed tPA treatment in various animal stroke models. However, only some have entered into clinical trials; the results have been intriguing yet unsatisfactory. In this narrative review, I describe such drugs and discuss the problems and future directions. These “tPA helpers” may be clinically used in the future to increase the efficacy of tPA in patients with acute ischemic stroke.
Animals ; Blood-Brain Barrier ; Brain ; Edema ; Humans ; Incidence ; Infarction ; Intracranial Hemorrhages ; Metalloproteases ; Mortality ; Neuroprotection ; Reperfusion Injury ; Stroke ; Tissue Plasminogen Activator ; Vascular Remodeling

PURPOSE: Metalloproteinases are a key component of the pathogenesis of abdominal hernias. Obesity is considered a risk factor in herniogenesis and hernia recurrence. The aim of this study was to evaluate the serum concentrations of metalloproteinase-2 (MMP-2), MMP-9, MMP-13, and adiponectin in morbidly obese and non-overweight controls. MATERIALS AND METHODS: The participants were recruited from among patients undergoing bariatric and non-bariatric surgery and divided into two groups: I (body mass index (BMI)≥35 kg/m², n=40) and II (BMI<25 kg/m², n=30). Serum concentrations of MMP-2, MMP-9, MMP-13, and adiponectin were measured using enzyme-linked immunosorbent assay (ELISA). RESULTS: A statistically significant difference between groups was observed for MMP-2 concentration. The median MMP-9 concentration was higher in the obese group, but the difference was not statistically significant. Median MMP-13 concentrations did not differ between groups. Serum adiponectin concentration was insignificantly higher in the non-obese group. CONCLUSIONS The elevated serum MMP-2 and MMP-9 concentrations in obese individuals may be related to the higher incidence of incisional hernias in this population.
Adiponectin/blood* ; Adult ; Aged ; Bariatric Surgery ; Body Mass Index ; Female ; Humans ; Incisional Hernia/blood* ; Male ; Matrix Metalloproteinase 13/blood* ; Matrix Metalloproteinase 2/blood* ; Matrix Metalloproteinase 9/blood* ; Metalloproteases/blood* ; Middle Aged ; Obesity, Morbid/surgery* ; ROC Curve ; Risk Factors ; Wound Healing ; Young Adult