Extracellular vesicles (EV) are blebs of cellular membranes, which entrap small portions of subjacent cytosol. They are released from a variety of cells, circulate in the blood for an unknown length of time and come to rest on endothelial surfaces. They contribute to an array of physiologic pathways, the complexity of which is still being investigated. They contribute to metastatic malignant cell implants and tumor-related angiogenesis, possibly abetted by the tissue factor that they carry. It is thought that the adherence of the EV to endothelium is dependent upon a combination of their P-selectin glycoprotein ligand-1 and exposed phosphatidylserine, the latter of which is normally hidden on the inner bilayer of the intact cellular membrane. This manuscript reviews what is known about EV origins, their clearance from the circulation and how they contribute to malignant cell implants upon endothelium surfaces and subsequent tumor growth.

Background Deep vein thrombosis (DVT) and pulmonary emboli (PE), known together as venous thromboembolic (VTE) disease remain major complications following elective hip and knee surgery. This study compares three chemoprophylactic regimens for VTE following elective primary unilateral hip or knee replacement, one of which was designed to minimize risk of post-operative bleeding. Methods Patients were randomized and stratified for hip vs. knee to receive A: variable dose warfarin (first dose on the night preceding surgery with subsequent target INR 2.0–2.5), B: 2.5 mg fondaparinux daily starting 6–18 h postoperatively, or C: fixed 1.0 mg dose warfarin daily starting 7 days preoperatively. All treatments continued until bilateral leg venous ultrasound day 28 ± 2 or earlier upon a VTE event. The study examined primary endpoints including leg DVT, PE or death due to VTE and secondary endpoints including effects on D-dimer, estimated blood loss (EBL) at surgery and hemorrhagic complications. Results Three hundred fifty-five patients were randomized. None was lost to follow-up. Taking 1.0 mg warfarin for seven days preoperatively did not prolong the prothrombin time (PT). Two patients in Arm C had asymptomatic distal DVT. One major bleed occurred in Arm B and one in Arm C (ischemic colitis). Elevated d-dimer did not predict delayed VTE for one year. Conclusions Fixed low dose warfarin started preoperatively is equivalent to two other standards of care under study (95 % CI: -0.0428, 0.0067 for both) as VTE prophylaxis for the patients having elective major joint replacement surgery. Trial registration ClinicalTrials.gov identifier # NCT00767559 FDA IND: 103,716

Background: Preoperative auto-blood donation has been shown to increase the likelihood of developing postoperative anemia following orthopedic surgery. This study was to assess the additive effect of intraoperative plus postoperative fluid resuscitation upon the relationship between preoperative donation and the frequency of postoperative transfusion. Methods: In this retrospective, single institution case-controlled study, hemoglobin levels, fluid administration, and incidence of transfusion were reviewed among 182 patients (91 donated blood preoperatively and 91 did not) undergoing total hip arthroplasty (THA) or total knee arthroplasty (TKA). Results: Thirty-two (35.2%) donors and 18 (19.8%) non-donors received transfusion for adjusted risk of 2.817 (1.301 - 6.100) among donors versus non-donors. Donors are more affected by the hemodilution effects associated with fluid infusion and are transfused earlier and more frequently than non-donors. Conclusion: Preoperative autologous donation and fluid administration increase the risk for receiving postoperative transfusion. J Hematol. 2015;4(2):157-163 doi: http://dx.doi.org/10.14740/jh208w

Markers for hypercoagulation can be used to explain why some patients may have had thromboembolic disease (TED). This information may then be applied to estimate risk for additional TED that may afflict these patients following subsequent surgeries. This investigation was to determine the frequency of hypercoagulation parameters among patients having had TED, and how frequently these occur in multiples. Consulting hematologists were asked to comment upon potential risk for recurrent TED that may be associated with additional surgeries. The consulting hematologist determined which laboratory tests were to be ordered for each patient. This retrospective study probed the hospital computer logs for patients having had homocysteine, protein C, factor V Leiden or anticardiolipin antibodies measured during a 6-year period. The laboratory records for patients having had any one of these tests were then examined further for any additional hypercoagulation laboratory studies performed. Five hundred and twenty patients were identified in this survey. Abnormal diagnostic results were found for 293 (56.3%) of these patients. Two or more abnormalities (up to 5) were found for 103 (35.6%) of these patients. Laboratory explanations for TED may be found in a large proportion of patients with TED. It is not uncommon to find more than one abnormality among these patients. This information may be used in advising patients and their physicians as to the risks of additional TED following future surgical procedures and can be the basis for recommending life style changes.

Abstract 4395 Prophylaxis against post-operative deep vein thrombosis using low dose warfarin is appealing as it is inexpensive and with low risk of hemorrhage. Investigators have examined this issue with variable outcomes. Critical to our thinking is that the drug must be started prior to the elective surgical intervention in order to be an effective antithrombotic agent, while not causing potential hemorrhagic anticoagulation. This abstract describes the effect of such a regimen on the generation of markers of coagulation activation, comparing fixed very low dose warfarin (1 mg daily) to variable dose warfarin among patients having elective replacement of hip or knee surgery. The fixed low dose warfarin is begun 7 days prior to surgery and continued 28 days post operatively. Variable dose warfarin is begun at 5 mg the night prior to surgery and is continued for 28 days post operatively with the target INR 2.0–2.5, adjusted twice per week. For this study the markers of coagulation activation are prothrombin fragment F1+2 and thrombin-anti-thrombin complex (T-AT). They are measured prior to start of warfarin therapy (baseline), on the morning of surgery (OR Day), and on postoperative days 3 and 28. PIVKA II is measured at the same time points as a measure of warfarin activity other than the INR. For this study 10 patients for each group are taken from a larger group of patients participating in a randomized prospective study of this regimen now in progress. Both studies are IRB approved. Table 1 demonstrates the results. As expected the PIVKA II is increased over normal for both groups by OR Day and on post-operative days 3 and 28. Greater increases in PIVKA II, as expected, occur among patients receiving variable dose warfarin, as this group received higher doses. The T-AT is elevated by post-operative day 3 and is returned to normal on post-operative day 28 in both groups. At each time point the T-AT values are equal for the two study groups. The F1+2 values are modestly increased for both groups on post-operative day 3, with better suppression of F1+2 generation by the variable dose regimen on day 28. In conclusion, the fixed low dose warfarin regimen is as effective as the variable dose warfarin as measured by the generation of T-AT, and is possibly somewhat less effective as determined by the generation of F1+2. The clinical significance of this difference is unknown, especially given the suppression of the T-AT. None of these patients suffered postoperative thromboembolic disease. Disclosures: Adcock: Esoterix Laboratory Services, Inc: Employment.

Plasminogen activator Inhibitor 1 (PAI-1) inhibits plasminogen activators leading to decreased fibrinolysis and increased risk of thromboembolic disease (TED). Shifts in PAI-1 promoter genome from normal 5G>5G to 4G>5G or 4G>4G alleles are associated with overexpression of PAI-1. In this study patients with residual venous thrombi were observed to have increased PAI-1 levels and more frequent shifts to 4G alleles. Of the 26, 20 (76.9%) patients with unresolved thrombus had elevated PAI-1 values. 4G genomic shifts were found in 92.9% patients studied. Normal PAI-1 levels were found in 5 patients with 4G polymorphisms. Thus, PAI-1 is often elevated among patients with residual thrombus, with an unexpectedly high prevalence of the 4G polymorphism of the promoter genome. Patients with persistent thrombus should be considered at risk of having constituently increased PAI-1 due to genomic changes in the PAI-1 promoter genome. Hypotheses are proposed to explain those with normal PAI-1, despite having 4G polymorphisms.

This abstract demonstrates the distribution of hypercoagulation diagnosis among patients with histories of thromboembolic disease (TED) among a group of patients detected at surgery prescreening clinic or through other referral sources. The consulting hematologists determined which laboratory tests were ordered; thus not all patients had all tests. This abstract describes the results of those clinical consultations. For this study the hospital's computer logs were probed for patients having had measurements of protein C and factor V Leiden from 11/7/01until 8/1/07. The laboratory records of identified patients were searched for additional hypercoagulation laboratory parameters. A total of 383 patients have been identified, among whom abnormal diagnostic results were found for 231. Genomic assays were performed often for the commonly found defects (i.e., factor V Leiden and prothrombin 20210) and selectively for other situations, such 4G/5G for patients with elevated plasminogen activator inhibitor 1 (PAI-1) and unresolved venous thrombus, or methylene tetrahydrofolate (MTH) reductace for unexplained elevation of homocysteine. The table demonstrate the distribution of these laboratory diagnoses. The risk of having TED associated with these results will be stratified to emphasize the increased risk associated with the more severe abnormalities of protein C, protein S, ATIII, PAI-1, and homocysteine. These results demonstrate that laboratory explanations for TED may be found in a large proportion of patients with TED, which thereafter can be used to design prophylactic programs for at risk patients upon entry to hospital, especially elective surgery.

Consecutive patients having elective total hip arthroplasty were prescribed 1 mg of warfarin for 7 days preceding surgery, variable doses while in hospital (target international normalized ratio, 1.5-2.0), and discharged to rehabilitation center or home taking 1 mg daily until 4-week to 6-week follow-up visit. Lower leg pneumatic compression was used postoperatively and elastic compression stockings after discharge. Hospital and clinic charts plus auxiliary sources were reviewed for evidence of thromboembolic diseases (TED). Of 1003 consecutive patients studied, 3 (0.3%, 95% CI 0.0-0.6%) had symptomatic TED, including 2 with deep venous thrombosis and 1 with nonfatal pulmonary embolus. Follow-up rate was 99.1%. Complications from warfarin were minimal. Very–low-dose warfarin coupled with lower leg compression is effective prophylaxis against TED after elective hip arthroplasty when prescribed as described.

Management of non-functional central venous catheters traditionally involves instillation of fibrinolytic agents, and if unsuccessful, removal and replacement of the catheter. Many of these catheters, however, are still usable for their original purposes. With time, collateral vessels open, allowing passage of fluids into the circulation. We attempted to preserve such catheters if they were not fractured and were not used for infusing sclerosing agents. In 75 patients, there were 91 occlusive events. Venograms, cathetergrams, or ultrasounds were used to detect the cause of catheter failure, searching for sheath thrombus, subclavian vein or superior vena cava thrombosis. Of the 75 patients, 9 had recurrent failures after original resolution. In 5, the catheter was removed due to sepsis. Therefore the total events available for analysis was 86. The various medical treatments included warfarin, heparin, low molecular weight heparin (LMWH) and fibrinolytics, and passage of time. Overall, 49 events were resolved. For 38 of these 49 events associated signs and symptoms resolved within one week. Thirty-four (34) catheters were removed due to persistent problems, including sepsis in 5. In 22 patients, the catheters remained functional until the patient’s death, and in 14 the catheters remained functional until completion of the patient’s therapy. Therefore, over half (54%) of the catheters associated with veno-occlusive events can be maintained with these medical approaches. Selective medical management should be applied to non-functioning central venous catheters to avoid added risk, inconvenience, and cost of their replacement.

Human monocytes have been shown to penetrate the endothelial layer of large blood vessels and to adhere to the subendothelial basement membrane. To determine the active components of this process, we have studied the ability of monocytes to adhere to isolated components of the subendothelial matrix. Using a quantitative dot-blot adhesion assay, we find that monocytes adhere preferen- tially to immobilized laminin and elastin. The monocytes adhere less well to fibronectin and bind poorly or not at all to collagen types I and IV, or to heparan sulfate. Monocyte binding to elastin requires an intact. crosslinked molecule as no binding was observed to soluble, acid-alcohol elastin I T HAS RECENTLY BEEN demonstrated that blood- borne mononuclear cells can penetrate the vascular endothelium in large blood vessels and adhere to the suben- dothelial basal lamina.'3 It has been suggested that these monocytes are the precursors of the lipid-laden foam cells associated with atherosclerotic lesions.4'5 Monocyte-derived growth factors may also mediate the smooth muscle cell migration and proliferation that is an early step in the pathogenesis of atherosclerosis.6'7 The molecules that mediate monocyte adhesion to the subendothelial extracellular matrix have not yet been deter- mined. It is possible that there are multiple determinants in the extracellular matrix (ECM) to which monocytes can adhere. To explore this question, we have tested several known components of the vascular ECM for their ability to bind monocytes. Our results demonstrate that monocytes and related leukocyte cell lines adhere preferentially to laminin and elastin. The cells adhere less well to fibronectin and do not bind appreciably to other matrix components.