Heparin is much more than just an anticoagulant

The Potential Role of Heparin in Patients With COVID-19: Beyond the Anticoagulant Effect. A Review

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection is responsible of variable clinical manifestations, ranging from no symptoms to severe pneumonia with acute respiratory distress syndrome, septic shock, and multi-organ failure resulting in death. To date no specific antiviral drug have been approved for COVID-19, so the treatment of the disease is mainly focused on symptomatic treatment and supportive care. Moreover, there are no treatments of proven efficacy to reduce the progression of the disease from mild/moderate to severe/critical. An activation of the coagulation cascade leading to severe hypercoagulability has been detected in these patients, therefore early anticoagulation may reduce coagulopathy, microthrombus formation, and the risk of organ damages. The role of heparin in COVID-19 is supported by a lot of studies describing its pleiotropic activity but it must be proven in clinical trials. Several protocols have been designed to assess the risk-benefit profile of heparin (low-molecular-weight or unfractionated heparin) in hospitalized subjects. Although prophylactic doses may be adequate in most patients, it is important to wait the results of clinical trials in order to define the appropriate effective dose able to improve disease outcome.

Osteogenic activities of MC3T3-E1 cells on heparin-immobilized poly(caprolactone) membranes

The aim of this study was to investigate the effects of heparin on the activity of osteoblast-like cells seeded on poly(caprolactone) (PCL) membranes. The membranes were prepared by solvent-casting technique in ~150 µm thickness. Then they were treated with 1,6-hexanediamine solution and functionalized with covalently bound heparin. The morphology, proliferation, and differentiation of MC3T3-E1 preosteoblasts on these membranes were investigated in vitro. The heparin functionalized PCL membranes, compared to non-functionalized membranes, significantly stimulated osteoblast proliferation. The Scanning electron microscope images confirmed the stimulative effect of covalently bound heparin on the osteoblast-like cell proliferation. The alkaline phosphatase and osteocalcin levels for cells proliferated on heparin containing PCL membranes were higher than that of nonfunctionalized membranes.

Electrochemical recognition of synthetic heparin mimetic at liquid/liquid microinterfaces

Electrochemically controlled molecular recognition of a synthetic heparin mimetic, Arixtra, at nitrobenzene/water microinterfaces was investigated to obtain a greater understanding of interfacial recognition and sensing of heparin and its analogues with biomedical importance. In contrast to unfractionated heparin, this synthetic pentasaccharide that mimics the unique Antithrombin III binding domain of heparin possesses well-defined structure and ionic charge to enable quantitative interpretation of cyclic voltammetric/chronoamperometric responses based on the interfacial recognition at micropipet electrodes. Arixtra is electrochemically extracted from the water phase into the bulk nitrobenzene phase containing highly lipophilic ionophores, methyltridodecylammonium or dimethyldioctadecylammonium. Numerical analysis of the kinetically controlled cyclic voltammograms demonstrates for the first time that formal potentials and standard rate constants of polyion transfer at liquid/liquid interfaces are ionophore dependent. Moreover, octadecylammonium and octadecylguanidinium are introduced as new, simple ionophores to model recognition sites of heparin-binding proteins at liquid/liquid interfaces. In comparison to octadecyltrimethylammonium, the best ionophore for heparin recognition at liquid/liquid interfaces reported so far, these new ionophores dramatically facilitate Arixtra adsorption at the interfaces. With a saline solution at physiological pH, an Arixtra molecule is selectively and cooperatively bound to 5 molecules of the guanidinium ionophore, suggesting hydrogen-bond-directed interactions of each guanidinium with a few of 10 negatively charged sulfo or carboxyl groups of Arixtra at the interfaces.

Coronary stents: a materials perspective

The objective of this review is to describe the suitability of different biomaterials as coronary stents. This review focuses on the following topics: (1) different materials used for stents, (2) surface characteristics that influence stent-biology interactions, (3) the use of polymers in stents, and (4) drug-eluting stents, especially those that are commercially available.

Titrimetric method for determination of O-desulfated heparin in physiological samples using protamine-sensitive membrane electrode as endpoint detector

O-Desulfated heparin (ODSH) is a promising new anti-inflammatory agent for the prevention of reperfusion injury following myocardial infarction or stroke. This partially desulfated heparin derivative has less anticoagulant activity than unfractionated heparin but retains the inherent anti-inflammatory properties of heparin. Thus, ODSH could be administered at the high doses needed to achieve desired anti-inflammatory function without risk of hemorrhage. However, given the very low anticoagulant activity of this species, traditional methods for heparin determination in clinical samples might not be well suited for ODSH measurements. In this article, a novel titrimetric method for detection of ODSH in buffer and plasma is described using a protamine-sensitive polymer membrane electrode as the detector. Titrations of ODSH with the heparin antagonist protamine yield sharp endpoints with sensitivity to ODSH in the micrograms per milliliter range for plasma samples. The stoichiometry for protamine interaction with ODSH is determined to average 1.39 microg protamine/microg ODSH in plasma. This technology is further applied to a toxicokinetic study of ODSH in an animal model, demonstrating the ability to detect the changes in ODSH concentrations in biological samples.

The systemic inflammatory response syndrome and cardiopulmonary bypass

Cardiac surgery using cardiopulmonary bypass (CPB) provokes a systemic inflammatory response. This is mainly triggered by contact activation of blood by artificial surfaces of the extracorporeal circuit. Although often remaining sub-clinical and resolving promptly at the end of CPB, in its most extreme form this inflammatory response may be associated with the development of the systemic inflammatory response syndrome (SIRS) that can often lead to major organ dysfunction (MODs) and death. Here, we review the pathophysiology behind the development of this "whole body" inflammatory response and some of the methods currently used to minimise it.