Effect of therapeutic plasma exchange on endothelial activation and coagulation-related parameters in septic shock.

BACKGROUND: A dysbalanced coagulation system is part of the pathological host response to infection in sepsis. Activation of pro-coagulant pathways and attenuation of anti-coagulant activity ultimately lead to microvascular stasis and consequent organ failure. No treatment approaches specifically targeting this axis are available. We explored the effects of therapeutic plasma exchange (TPE) on microvascular coagulation dysbalance in septic shock. METHODS: We conducted a prospective single-center study enrolling 31 patients with early septic shock (onset < 12 h) requiring high doses of norepinephrine (NE > 0.4 µg/kg/min). Clinical and biochemical data, including measurement of protein C; a disintegrin and metalloprotease with a thrombospondin type 1 motif, member 13 (ADAMTS13); and von Willebrand factor antigen (vWF:Ag), were obtained before and after TPE against fresh frozen plasma. RESULTS: Antithrombotic acting proteins such as antithrombin-III (ATIII) and protein C were markedly reduced in septic patients, but their activity increased after TPE (ATIII, 51% (41-61) vs. 63% (48-70), p = 0.029; protein C, 47% (38-60) vs. 62% (54-69), p = 0.029). Median ADAMTS13 activity was increased by TPE from 27 (21-42) % before to 47 (38-62) % after TPE (p < 0.001). In contrast, vWF:Ag was elevated and could be reduced by TPE (353 (206-492) IU/dL vs. 170 (117-232) IU/dL, p < 0.001). Regression analysis yielded a correlation between ADAMTS13 activity and platelet count (p = 0.001, R2 = 0.316). CONCLUSIONS: Septic shock was associated with activation of pro-coagulant pathways and simultaneous depletion of anti-coagulant factors. TPE partially attenuated this dysbalance by removing pro- and by replacing anti-coagulant factors. TRIAL REGISTRATION: ClinicalTrials.gov, NCT03065751. Retrospectively registered on 28 February 2017.

Proteomics identifies thymidine phosphorylase as a key regulator of the angiogenic potential of colony-forming units and endothelial progenitor cell cultures.

Endothelial progenitor cell (EPC) cultures and colony-forming units (CFUs) have been extensively studied for their therapeutic and diagnostic potential. Recent data suggest a role for EPCs in the release of proangiogenic factors. To identify factors secreted by EPCs, conditioned medium from EPC cultures and CFUs was analyzed using a matrix-assisted laser desorption/ionization tandem time-of-flight mass spectrometer combined with offline peptide separation by nanoflow liquid chromatography. Results were verified by RT-PCR and multiplex cytokine assays and complemented by a cellular proteomic analysis of cultured EPCs and CFUs using difference in-gel electrophoresis. This extensive proteomic analysis revealed the presence of the proangiogenic factor thymidine phosphorylase (TP). Functional experiments demonstrated that inhibition of TP by 5-bromo-6-amino-uracil or gene silencing resulted in a significant increase in basal and oxidative stress-induced apoptosis, whereas supplementation with 2-deoxy-D-ribose-1-phosphate (dRP), the enzymatic product of TP, abrogated this effect. Moreover, dRP produced in EPC cultures stimulated endothelial cell migration in a paracrine manner, as demonstrated by gene-silencing experiments in transmigration and wound repair assays. RGD peptides and inhibitory antibodies to integrin alphavbeta3 attenuated the effect of conditioned medium from EPC cultures on endothelial migration. Finally, the effect of TP on angiogenesis was investigated by implantation of Matrigel plugs in mice. In these in vivo experiments, dRP strongly promoted neovascularization. Our data support the concept that EPCs exert their proangiogenic activity in a paracrine manner and demonstrate a key role of TP activity in their survival and proangiogenic potential.

IFATS collection: Identification of hemangioblasts in the adult human adipose tissue.

The stromal-vascular fraction (SVF) of human adipose tissue contains, among other cell types, mesenchymal stem cells and precursors of adipocyte and endothelial cells. Here we show that, in addition, the nonhematopoietic fraction of the SVF has hematopoietic activity, since all types of hematopoietic colony-forming units (CFUs) developed when cultured in methylcellulose-based medium. This hematopoietic activity was restricted to the CD45(-)CD105(+) cell subset, well correlated with KDR(+) cell content, and increased after culture with a combination of early-acting hematopoietic cytokines. Most of the CD45(-)KDR(+)CD105(+) cells were nonadherent and did not express CD31, and this subset included both CD34(-) and CD34(+) cells. Moreover, these nonadherent cells migrated in response to KDR gradient, and when they were cultured in the presence of both hematopoietic and endothelial growth factors, a wave of CFUs was followed by a wave of mixed colonies comprising adherent elongated and nonadherent round hematopoietic cells. These mixed hematopoietic-endothelial (Hem-End) colonies were able to generate secondary Hem-End colonies and exhibited both hematopoietic and endothelial activity, as demonstrated by in vitro functional assays. These findings demonstrate for the first time the existence of primitive mesodermal progenitors within the SVF of human adipose tissue that exhibit in vitro hematopoietic and hemangioblastic activities, susceptible to being used in cell therapy and basic cell research. Disclosure of potential conflicts of interest is found at the end of this article.