Butyrate Increases Heparin Synthesis and Storage in Human Mast Cells.

Sulphated glycosaminoglycans (GAGs) such as heparin are a major component of mast cell granules and form the matrix within which biogenic mediators are stored. Since GAGs released from mast cells also play an important role in helminth expulsion, understanding GAG storage can offer new insights into mast cell function. Sodium butyrate (NaBu), a short-chain fatty acid, causes ultrastructural changes within the granules of human mast cells (HMC-1) and increases their histamine content. Therefore, we hypothesized that NaBu treatment would also modify the storage of polysaccharides such as GAGs. NaBu (1 mM) significantly increased GAG content and granularity in a time- and concentration-dependent manner without affecting cell viability and metabolic activity. NaBu increased the expression of enzymes associated with heparin biosynthesis (GLCE, NDST1, NDST2, HS6ST1, and GALT1) in a time-dependent manner. A cholesteryl butyrate emulsion (CholButE) increased heparin content after 24 and 48 h and modestly altered the expression of genes involved in heparin biosynthesis. Similar to NaBu, CholButE reduced cell proliferation without significantly altering viability or metabolic activity. These data show that butyrate increases the synthesis and storage of heparin in human mast cells, perhaps by altering their metabolic pathways.

Safety and efficacy of drug-eluting stents versus heparin-bonded stents in treatment of femoropopliteal peripheral artery disease: study protocol for a multicentre, prospective randomised controlled trial in China (ELITE trial).

INTRODUCTION: Endovascular therapy has emerged as a prominent strategy for managing femoropopliteal peripheral artery disease, offering acceptable safety and efficacy compared with open surgical bypass. Both paclitaxel-eluting stents and heparin-bonded covered stents have exhibited enhanced clinical outcomes compared with bare metal stents. However, there is currently a lack of level I evidence comparing the safety and efficacy of paclitaxel-eluting stents and heparin-bonded covered stents. Therefore, the primary objective of this study is to systematically evaluate the efficacy and safety outcomes of these two types of stents. METHODS AND ANALYSIS: The ELITE trial is a prospective, multicentre, parallel, randomised controlled trial. A total of 450 patients will be recruited. The primary endpoints of the study include primary patency at 1 year post-index procedure. ETHICS AND DISSEMINATION: Ethical approval for this study was obtained from the Ethics Committee of West China Hospital of Sichuan University (approval number: 2023-1186). The results will be submitted to a major clinical journal for peer review and publication. TRIAL REGISTRATION: ELITE trial was registered on 27 September 2023 in the Chinese Clinical Trials Registry (ChiCTR2300076236).

Heparin Induced Thrombocytopenia Testing.

This article provides a comprehensive overview of Heparin-Induced Thrombocytopenia (HIT) with an emphasis on laboratory testing and advantages of automation. HIT is a critical condition arising from heparin exposure, leading to a contradictory combination of thrombocytopenia with an increased thrombosis risk. The article discusses HIT's history, clinical presentation, laboratory diagnosis, and management strategies. It highlights the importance of interdisciplinary collaboration for effective diagnosis and treatment, underscoring advancements in technology and targeted therapies that are shaping future approaches to HIT management.

The Effects of Different Blood Sample and Anticoagulant Types on Quantitative Tests of B-Type Natriuretic Peptide.

BACKGROUND: BNP is a sensitive and widely used biomarker for an early diagnosis of heart failure. Currently, most commercial BNP detection products use EDTA plasma samples. The aim of this study was to evaluate the clinical performance of the BNP test by using whole blood samples compared to plasma samples, and to evaluate the effect of the anticoagulant type on the BNP test result. METHODS: In total, 106 patients with different BNP levels from the Dahua Hospital volunteered for this study. Clinically homogenous samples, including EDTA anticoagulant plasma, EDTA whole blood, and heparin anticoagulant plasma, were collected and analyzed by using i-Reader S automatic immuno-analyzer and its supporting reagent kits. Pearson's correlation and weighted least squares linear regression analysis, Bland-Altman plotting, and Kappa test were used for statistical analysis. RESULTS: Correlation analysis showed that BNP concentrations, measured from EDTA anticoagulated plasma samples, had a good linear regression relationship with BNP from whole blood samples, with a slope of 0.9477, r = 0.9978, p < 0.05. A similar correlation was observed between EDTA anticoagulated plasma samples and heparin anticoagulant plasma, with a slope of 0.8413, r = 0.9793, p < 0.05. The BNP concentration measured from the heparin plasma samples were lower than of the EDTA plasma samples. Bland-Altman analysis for assessing BNP concentration agreement showed there was no outlier ratio between EDTA whole blood and EDTA plasma within the range of the detection system, as well as no outlier between EDTA anticoagulated and heparin anticoagulant plasma. Kappa coefficient of BNP concentration between homologous EDTA anticoagulated and heparin anticoagulant plasma was 0.8553 (p < 0.001), and for EDTA anticoagulated plasma and homologous whole blood it was 0.8941 (p < 0.001). CONCLUSIONS: The diagnostic performance of EDTA anticoagulated whole blood samples did not differ significantly from EDTA anticoagulated plasma samples for the BNP test. This study showed no big significant difference between EDTA anticoagulated and heparin anticoagulated plasma measurements within 2 hours. The type of anticoagulant should be carefully chosen when performing the BNP test if BNP samples were in vitro for a long time.

Preventing adverse events during paediatric cancer treatment: protocol for a multi-site hybrid randomised controlled trial of catheter lock solutions (the CLOCK trial).

INTRODUCTION: Central venous access devices (CVADs) are commonly used for the treatment of paediatric cancer patients. Catheter locking is a routine intervention that prevents CVAD-associated adverse events, such as infection, occlusion and thrombosis. While laboratory and clinical data are promising, tetra-EDTA (T-EDTA) has yet to be rigorously evaluated or introduced in cancer care as a catheter lock. METHODS AND ANALYSIS: This is a protocol for a two-arm, superiority type 1 hybrid effectiveness-implementation randomised controlled trial conducted at seven hospitals across Australia and New Zealand. Randomisation will be in a 3:2 ratio between the saline (heparinised saline and normal saline) and T-EDTA groups, with randomly varied blocks of size 10 or 20 and stratification by (1) healthcare facility; (2) CVAD type and (3) duration of dwell since insertion. Within the saline group, there will be a random allocation between normal and heparin saline. Participants can be re-recruited and randomised on insertion of a new CVAD. Primary outcome for effectiveness will be a composite of CVAD-associated bloodstream infections (CABSI), CVAD-associated thrombosis or CVAD occlusion during CVAD dwell or at removal. Secondary outcomes will include CABSI, CVAD-associated-thrombosis, CVAD failure, incidental asymptomatic CVAD-associated-thrombosis, other adverse events, health-related quality of life, healthcare costs and mortality. To achieve 90% power (alpha=0.05) for the primary outcome, data from 720 recruitments are required. A mixed-methods approach will be employed to explore implementation contexts from the perspective of clinicians and healthcare purchasers. ETHICS AND DISSEMINATION: Ethics approval has been provided by Children's Health Queensland Hospital and Health Service Human Research Ethics Committee (HREC) (HREC/22/QCHQ/81744) and the University of Queensland HREC (2022/HE000196) with subsequent governance approval at all sites. Informed consent is required from the substitute decision-maker or legal guardian prior to participation. In addition, consent may also be obtained from mature minors, depending on the legislative requirements of the study site. The primary trial and substudies will be written by the investigators and published in peer-reviewed journals. The findings will also be disseminated through local health and clinical trial networks by investigators and presented at conferences. TRIAL REGISTRATION NUMBER: ACTRN12622000499785.

The association between heparin sensitivity index and postoperative blood loss in Chinese patients undergoing elective off-pump coronary artery bypass grafting: a single center retrospective study.

BACKGROUND: The heparin sensitivity index (HSI) is closely associated with perioperative ischemic events and increased blood loss in cardiac surgery. Previous studies have produced conflicting results. Therefore, this study aimed to investigate the relationship between HSI and postoperative blood loss specifically in Chinese patients undergoing elective off-pump coronary artery bypass grafting (OPCAB). METHODS: Patients underwent OPCAB between March 2021 and July 2022 were retrospectively included. Enrolled patients were classified into Low-HSI (HSILOW; HSI < 1.3) and Normal-HSI (HSINORM; HSI ≥ 1.3) groups. HSI = [(activated clotting time (ACT) after heparin) - (baseline ACT)] / [loading dose of heparin (IU/kg)]. Primary outcome included postoperative blood loss at 24 h. Secondary outcomes were total postoperative blood loss, transfusion requirement of red blood cell (RBC), fresh frozen plasma (FFP), platelet concentrates (PC), and other complications. RESULTS: We retrospectively analyzed 303 Chinese OPCAB patients. HSILOW group had higher preoperative platelet (PLT) count (221 × 109/L vs. 202 × 109/L; P = 0.041) and platelet crit (PCT) value (0.23% vs. 0.22%; P = 0.040) compared to HSINORM group. Two groups showed no significant differences in postoperative blood loss at 24 h (460 mL vs. 470 mL; P = 0.252), total blood loss (920 mL vs. 980 mL; P = 0.063), RBC transfusion requirement (3.4% vs. 3.1%; P = 1.000), FFP transfusion requirement (3.4% vs. 6.2%; P = 0.380), and other complications. Preoperative high PLT count was associated with low intraoperative HSI value (odds ratio: 1.006; 95% confidence interval: 1.002, 1.011; P = 0.008). CONCLUSIONS: Intraoperative HSI value was not associated with postoperative blood loss in Chinese patients undergoing OPCAB. Preoperative high PLT count was an independent predictor of low intraoperative HSI value.

Fault in Our Genes: A Case of Pulmonary Thromboembolism in Young.

Methylenetetrahydrofolate reductase (MTHFR) enzyme is one of the key enzymes involved in the metabolism of folate. Mutations in this enzyme can lead to a procoagulant state. We present a case of a 20-year-old male with no known comorbidities, who presented with fever and hemoptysis and was diagnosed as a case of pulmonary embolism. He was found to have a homozygous mutation in the MTHFR gene that was responsible for his disease state. He was started on unfractionated heparin infusion and underwent catheter-directed thrombolysis. He showed marked improvement in his condition and was discharged on oral anticoagulants with an advice to follow-up.

RésuméL'enzyme méthylènetétrahydrofolate réductase (MTHFR) est l'une des enzymes clés impliquées dans le métabolisme du folate. Les mutations de cette enzyme peuvent conduire à un état procoagulant. Nous présentons le cas d'un homme de 20 ans sans comorbidités connues, qui s'est présenté avec de la fièvre et une hémoptysie et a été diagnostiqué comme un cas d'embolie pulmonaire. Il s'est avéré qu'il présentait une mutation homozygote du gène MTHFR responsable de son état pathologique. Il a commencé une perfusion d'héparine non fractionnée et a subi une thrombolyse dirigée par cathéter. Il a montré une nette amélioration de son état et a été libéré sous anticoagulants oraux avec un conseil de suivi.

Analysis of arterial blood gas values when discarding different volumes of blood samples in an arterial heparin blood collector during thoracoscopic surgery.

BACKGROUND: Arterial blood gas analysis (ABGA) plays a vital role in emergency and intensive care, which is affected by many factors, such as different instrumentation, temperature, and testing time. However, there are still no relevant reports on the difference in discarding different blood volumes on ABGA values. METHODS: We enrolled 54 patients who underwent thoracoscopic surgery and analysed differences in blood gas analysis results when different blood volumes were discarded from the front line of the arterial heparin blood collector. A paired t test was used to compare the results of the same patient with different volumes of blood discarded from the samples. The difference was corrected by Bonferroni correction. RESULTS: Our results demonstrated that the PaO2, PaCO2, and THbc were more stable in the 4th ml (PaO2 = 231.3600 ± 68.4878 mmHg, PaCO2 = 41.9232 ± 7.4490 mmHg) and 5th ml (PaO2 = 223.7600 ± 12.9895 mmHg, PaCO2 = 42.5679 ± 7.6410 mmHg) blood sample than in the 3rd ml (PaO2 = 234.1000 ± 99.7570 mmHg, PaCO2 = 40.6179 ± 7.2040 mmHg). CONCLUSION: It may be more appropriate to discard the first 3 ml of blood sample in the analysis of blood gas results without wasting blood samples.

Heparan sulfate-dependent phase separation of CCL5 and its chemotactic activity.

Secreted chemokines form concentration gradients in target tissues to control migratory directions and patterns of immune cells in response to inflammatory stimulation; however, how the gradients are formed is much debated. Heparan sulfate (HS) binds to chemokines and modulates their activities. In this study, we investigated the roles of HS in the gradient formation and chemoattractant activity of CCL5 that is known to bind to HS. CCL5 and heparin underwent liquid-liquid phase separation and formed gradient, which was confirmed using CCL5 immobilized on heparin-beads. The biological implication of HS in CCL5 gradient formation was established in CHO-K1 (wild-type) and CHO-677 (lacking HS) cells by Transwell assay. The effect of HS on CCL5 chemoattractant activity was further proved by Transwell assay of human peripheral blood cells. Finally, peritoneal injection of the chemokines into mice showed reduced recruitment of inflammatory cells either by mutant CCL5 (lacking heparin-binding sequence) or by addition of heparin to wild-type CCL5. Our experimental data propose that co-phase separation of CCL5 with HS establishes a specific chemokine concentration gradient to trigger directional cell migration. The results warrant further investigation on other heparin-binding chemokines and allows for a more elaborate insight into disease process and new treatment strategies.

Heparin is an effective treatment for preventing liver failure after hepatectomy.

BACKGROUND: Posthepatectomy liver failure (PHLF) is one of the most important causes of death following liver resection. Heparin, an established anticoagulant, can protect liver function through a number of mechanisms, and thus, prevent liver failure. AIM: To look at the safety and efficacy of heparin in preventing hepatic dysfunction after hepatectomy. METHODS: The data was extracted from Multiparameter Intelligent Monitoring in Intensive Care III (MIMIC-III) v1. 4 pinpointed patients who had undergone hepatectomy for liver cancer, subdividing them into two cohorts: Those who were injected with heparin and those who were not. The statistical evaluations used were unpaired t-tests, Mann-Whitney U tests, chi-square tests, and Fisher's exact tests to assess the effect of heparin administration on PHLF, duration of intensive care unit (ICU) stay, need for mechanical ventilation, use of continuous renal replacement therapy (CRRT), incidence of hypoxemia, development of acute kidney injury, and ICU mortality. Logistic regression was utilized to analyze the factors related to PHLF, with propensity score matching (PSM) aiming to balance the preoperative disparities between the two groups. RESULTS: In this study, 1388 patients who underwent liver cancer hepatectomy were analyzed. PSM yielded 213 matched pairs from the heparin-treated and control groups. Initial univariate analyses indicated that heparin potentially reduces the risk of PHLF in both matched and unmatched samples. Further analysis in the matched cohorts confirmed a significant association, with heparin reducing the risk of PHLF (odds ratio: 0.518; 95% confidence interval: 0.295-0.910; P = 0.022). Additionally, heparin treatment correlated with improved short-term postoperative outcomes such as reduced ICU stay durations, diminished requirements for respiratory support and CRRT, and lower incidences of hypoxemia and ICU mortality. CONCLUSION: Liver failure is an important hazard following hepatic surgery. During ICU care heparin administration has been proved to decrease the occurrence of hepatectomy induced liver failure. This indicates that heparin may provide a hopeful option for controlling PHLF.

[Heparin Resistance After Administration of Andexanet Alfa:Report of a Case].

The management of patients on direct oral anticoagulants (DOACs) who require an emergency cardiac surgery has been disputed in Japan. Recently, the use of andexanet alfa as an antidote for apixaban and rivaroxaban, is approved in the setting of life-threating or uncontrollable major bleeding. However, the efficacy and safety of andexanet alfa have been investigated. We report a case of 72-year-old man taking rivaroxaban who required the emergency coronary artery bypass grafting. He received andexanet alfa prior to the operation. Heparin resistance was noted before starting cardiopulmonary bypass. Consideration should be given to the use of andexanet alfa before or during cardiopulmonary bypass.

Reduced Radial Artery Occlusion in Transradial Cerebral Angiography: Key Predictive Factors and Preventive Measures from a Single-Center Study of 543 Patients.

BACKGROUND The transradial approach (TRA) for cerebral angiography and neurointerventional treatment has gained popularity, but the narrow diameter and weak pulsation of the radial artery lower the initial puncture success rate compared to femoral artery puncture. This retrospective study from a single center evaluated the incidence of and factors associated with radial artery occlusion (RAO) in 543 patients who underwent transradial approach (TRA) for cerebral angiography. MATERIAL AND METHODS We included 543 patients who underwent TRA from July 2021 to February 2024. Ultrasound was used to determine whether the radial artery was occluded. Relevant clinical data were recorded to assess the incidence of and factors affecting RAO. RESULTS At 24 h after DSA, we performed ultrasound imaging. The patients were divided into an RAO group (n=32) and a non-RAO group (n=511). Results showed that RAO was significantly higher in patients who did not have add heparin to the antispasmodic agents, and they were more likely to have needed more than 3 radial artery puncture attempts, and tended to have received an 11-cm radial artery sheath with the Cordis puncture needles (all P<0.05). Multiple regression logistic analysis showed that adding heparin to the antispasmodic agents (OR=0.076, 95% CI: 0.018-0.321, P<0.001), having fewer than 3 radial artery puncture attempts (OR=0.245, 95% CI: 0.111-0.541, P<0.001), using a 16-cm radial artery sheath (OR=0.195, 95% CI: 0.067-0.564, P=0.003), and using Terumo puncture needles (OR=0.325, 95% CI: 0.148-0.717, P=0.005) can reduce the incidence of radial artery occlusion. CONCLUSIONS Our center found that adding heparin to the antispasmodic agents reduced the number of radial artery punctures attempts, and using a 16-cm radial artery sheath significantly lowered the incidence of early RAO after transradial cerebral angiography.

Photoresponsive heparin ionic complexes toward controllable therapeutic efficacy of anticoagulation.

Controllable heparin-release is of great importance and necessity for the precise anticoagulant regulation. Efforts have been made on designing heparin-releasing systems, while, it remains a great challenge for gaining the external-stimuli responsive heparin-release in either intravenous or catheter delivery. In this study, an azobenzene-containing ammonium surfactant is designed and synthesized for the fabrication of photoresponsive heparin ionic complexes through the electrostatic complexation with heparin. Under the assistance of photoinduced trans-cis isomerization of azobenzene, the obtained heparin materials perform reversible athermal phase transition between ordered crystalline and isotropic liquid state at room temperature. Compared to the ordered state, the formation of isotropic state can effectively improve the dissolving of heparin from ionic materials in aqueous condition, which realizes the photo-modulation on the concentration of free heparin molecules. With good biocompatibility, such a heparin-releasing system addresses photoresponsive anticoagulation in both in vitro and in vivo biological studies, confirming its great potential clinical values. This work provides a new designing strategy for gaining anticoagulant regulation by light, also opening new opportunities for the development of photoresponsive drugs and biomedical materials based on biomolecules.

PON1 enzyme activity assays for serum and heparinized plasma in horses and stability evaluation of the enzyme activity over different freeze-thaw cycles and mimic transportation.

Consistent information and standardization procedures regarding the time of storage for frozen samples and the effects of storage time on enzyme activity are still missing in the literature. Thus, we evaluated the effects of different storage temperatures (-20 °C and - 80 °C), three repetitive freeze/thaw cycles, and 24-h mimic transportation on the activities of PON1 (paraoxonase and arylesterase), enzymes involved in the protection and detoxification processes of reactive molecules. PON1 enzymes' activity was validated on serum and heparinized plasma in horses. The results revealed that conditions and time of storage of blood samples for PON1 analyses altered the activities of both enzymes in both sample types, evidencing that these conditions can lead to protein degradation or general alteration. Specifically, paraoxonase and arylesterase activities significantly decreased among storage temperatures, with major effects detected at -20 °C. The repeated freeze/thaw cycles at -20 °C and 24-h mimic transport conditions also generated an expected degradation of the arylesterase in both serum and heparinized plasma while freeze/thaw cycles at -80 °C caused an increase of both arylesterase and paraoxonase activities on both sample types. In general, similar enzyme responses were detected between serum and heparinized plasma.

Initial Experience with the Derivo 2Heal Flow Diverter under Standard or Reduced-Dose Single Antiplatelet Therapy.

BACKGROUND AND PURPOSE: Flow diverters with surface modifications or coatings have been recently introduced to clinical practice with the expectation that they can reduce the rate of thromboembolic complications and residual aneurysms. The purpose of this study is to evaluate the utility of the Derivo 2Heal (D2H) device, a new fibrin and heparin-coated flow diverter. MATERIALS AND METHODS: Patients treated by a single operator by using the D2H were retrospectively evaluated for demographic data, aneurysm characteristics, procedural variables, and follow-up data. All patients were treated by using a single D2H, monitored by platelet function testing and kept under single antiplatelet therapy with regular or half-dose clopidogrel or prasugrel after the procedure. RESULTS: Twenty patients with 26 aneurysms were treated. Three presented acutely with subarachnoid hemorrhage. Adjunctive devices were used in 6 patients. There were no technical failures and 2 periprocedural self-limited nonthrombotic minor adverse events. During follow-up, 1 of the acutely ruptured aneurysms reruptured, and 1 patient had a visual TIA. All patients were doing well clinically (19 with mRS of 0 and 1 with 1) at the last follow-up after discharge. The rates of total occlusion on very early angiographic (MRA/CTA or DSA, mean: 2.4 months), DSA (mean: 5.8 months), and midterm angiographic (mean: 14.5 months) follow-up for all versus uncoiled aneurysms were 68% versus 70%, 77.8% versus 90.0%, and 91.7% versus 90.1%, respectively. CONCLUSIONS: The absence of permanent neurologic deficits in the periprocedural period and favorable occlusion rates in this preliminary study suggest that the novel coating comprising fibrin and heparin may have the potential to increase the safety and efficacy of flow diversion and needs to be further studied by comparing the D2H device with its bare counterpart and other coated or surface-modified flow diverters.

Heparin binding induced supramolecular chirality into the self-assembly of perylenediimide bolaamphiphile.

Chirality is one of the hallmarks of biomolecules. Herein, we utilize heparin, a chiral biomolecule and potent drug, to induce chiral organization into the assembly of an achiral molecule. Polyanionic heparin binds with a dicationic perylenediimide derivative to induce supramolecular helical organization in aqueous medium as well as in a highly competitive cell culture medium.

Identification of heparin-binding amino acid residues in antibody HS4C3 with the potential to design antibodies against heparan sulfate domains.

Heparan sulfate (HS) is a linear polysaccharide with high structural and functional diversity. Detection and localization of HS in tissues can be performed using single chain variable fragment (scFv) antibodies. Although several anti-HS antibodies recognizing different sulfation motifs have been identified, little is known about their interaction with HS. In this study the interaction between the scFv antibody HS4C3 and heparin was investigated. Heparin-binding lysine and arginine residues were identified using a protect and label methodology. Site-directed mutagenesis was applied to further identify critical heparin-binding lysine/arginine residues using immunohistochemical and biochemical assays. In addition, computational docking of a heparin tetrasaccharide towards a 3-D homology model of HS4C3 was applied to identify potential heparin-binding sites. Of the 12 lysine and 15 arginine residues within the HS4C3 antibody, 6 and 9, respectively, were identified as heparin-binding. Most of these residues are located within one of the complementarity determining regions (CDR) or in their proximity. All basic amino acid residues in the CDR3 region of the heavy chain were involved in binding. Computational docking showed a heparin tetrasaccharide close to these regions. Mutagenesis of heparin-binding residues reduced or altered reactivity towards HS and heparin. Identification of heparin-binding arginine and lysine residues in HS4C3 allows for better understanding of the interaction with HS and creates a framework to rationally design antibodies targeting specific HS motifs.

Heparin as a Potential Therapeutic Substance for Post-Traumatic Stress Disorder.

In sexually mature male Wistar rats with modeled post-traumatic stress disorder, personalized characteristics of neurobiological reactions in the population of predator-induced stress-resilient and stress-susceptible heparinized animals were determined. Characteristics of the systemic response of immune mechanisms, hypothalamic-pituitary-adrenal axis, behavioral manifestations, as well as basic properties of the CNS (excitation/inhibition) are presented. The study demonstrated encouraging positive results of the course administration of unfractionated heparin at a dose below the therapeutic and prophylactic doses. The inclusion of heparin drugs into the clinical practice for the treatment of post-traumatic stress disorder will not require large-scale clinical trials, because many effects of heparin as a nonspecific adaptogen are well studied. Moreover, these properties were confirmed at a higher technological level during the COVID-19 pandemic.

Protamine and Heparin Interactions: A Narrative Review.

ABSTRACT: Protamine, first isolated from salmon fish sperm and now produced through recombinant biotechnology, is an antidote that neutralizes the anticoagulant properties of heparin. Protamine function is based on the capacity to dissociate the heparin-antithrombin III (AT III) complex (an important link that promotes blood fluidification by inhibiting coagulation), forming the inactive heparin-protamine complex. Protamine has itself dose-dependent anticoagulant properties: It interferes with coagulation factors and platelet function; it stimulates fibrinolysis; it can lead to thrombocytopenia and reduction in thrombin-related platelet aggregation; it decreases platelet response to thrombin receptor agonist in a dose-dependent manner. In this review, we will focus on protamine and its interaction with heparin. Notably, protamine is able to antagonize not only unfractionated heparin (UFH) but also low molecular weight heparins to various degrees. Protamine-allergic and anaphylactoid systemic reactions may affect up to 1 in 10 people and should be prevented and treated early.

Decellularized, Heparinized Small-Caliber Tissue-Engineered "Biological Tubes" for Allograft Vascular Grafts.

There remains a lack of small-caliber tissue-engineered blood vessels (TEBVs) with wide clinical use. Biotubes were developed by electrospinning and in-body tissue architecture (iBTA) technology to prepare small-caliber TEBVs with promising applications. Different ratios of hybrid fibers of poly(l-lactic-co-ε-caprolactone) (PLCL) and polyurethane (PU) were obtained by electrospinning, and the electrospun tubes were then implanted subcutaneously in the abdominal area of a rabbit (as an in vivo bioreactor). The biotubes were harvested after 4 weeks. They were then decellularized and cross-linked with heparin. PLCL/PU electrospun vascular tubes, decellularized biotubes (D-biotubes), and heparinized combined decellularized biotubes (H + D-biotubes) underwent carotid artery allograft transplantation in a rabbit model. Vascular ultrasound follow-up and histological observation revealed that the biotubes developed based on electrospinning and iBTA technology, after decellularization and heparinization cross-linking, showed a better patency rate, adequate mechanical properties, and remodeling ability in the rabbit model. IBTA technology caused a higher patency, and the heparinization cross-linking process gave the biotubes stronger mechanical properties.