Continuous platelet infusion in patient refractory to platelet transfusion : a retrospective study.

editorial reviewedPlatelet transfusion is commonly used for the prevention of bleeding in central thrombocytopenia. It is estimated that 7-34 % of chronically transfused patients become progressively refractory until they no longer have an increase in post-transfusion platelet count. In this case, and in the presence of bleeding, a therapeutic option is continuous transfusion (CT) of platelet concentrates (PC). We performed a retrospective study of patients at the University Hospital of Liege who received a CT between 01/01/2019 and 31/12/2020. We explored the etiology, immune or non-immune, of the refractory state and analyzed the clinical and biological evolution after TC. In our cohort, 13 patients received CT during the study period; for 8 of them, the refractory state was explained by non-immune causes. The mean platelet count increased during CT and in 61 % of cases, an improvement in bleeding symptomatology was obtained.La transfusion plaquettaire est couramment utilisée pour la prévention des saignements en cas de thrombopénie centrale. On estime que 7 à 34 % des patients transfusés chroniquement deviennent progressivement réfractaires jusqu’à ne plus présenter d’augmentation de la numération plaquettaire post-transfusionnelle. Dans ce cas, et en présence de saignements, une option thérapeutique correspond à la transfusion continue (TC) de concentrés plaquettaires (CP). Nous avons réalisé une étude rétrospective sur les patients du CHU de Liège ayant reçu une TC entre le 01/01/2019 et le 31/12/2020. Nous avons exploré l’étiologie, immune ou non immune, de l’état réfractaire et analysé l’évolution clinique et biologique après TC. Dans notre cohorte, 13 patients ont bénéficié de TC durant la période étudiée; pour 8 d’entre eux, l’état réfractaire s’expliquait par des causes non immunes. La numération plaquettaire moyenne a augmenté durant la TC et, dans 61 % des cas, une amélioration de la symptomatologie hémorragique a été obtenue

How to explore… Inherited platelet disorders

peer reviewedInherited platelet disorders (IPD) include a set of rare diseases whose diagnosis is often difficult because it requires the use of complex biological assays in specialized centers. They are probably under-diagnosed. Clinicians should consider an IPD when facing a chronic thrombocytopenia resistant to intravenous immunoglobulins (IVIG) and steroids together with a family history of thrombocytopenia. A syndromic thrombocytopenia will be suspected by the family survey and specific clinical signs. The confirmation of the diagnosis will then require the use of specialized biological assays such as platelet aggregation, flow cytometry, electron microscopy, platelet secretion assays, karyotype and molecular biology.Les thrombopénies et thrombopathies constitutionnelles constituent un ensemble de pathologies rares dont le diagnostic est souvent difficile car il nécessite le recours à des analyses biologiques souvent réservées à des centres spécialisés. Elles sont probablement sous-diagnostiquées. Le clinicien devra les envisager devant une thrombopénie chronique ne répondant pas aux immunoglobulines intraveineuses et aux corticoïdes et la présence d’antécédents familiaux. Une thrombopénie syndromique sera suspectée en fonction des éléments de l’anamnèse familiale et de signes cliniques spécifiques. La confirmation du diagnostic nécessitera la réalisation d’examens biologiques spécialisés (agrégation plaquettaire, cytométrie en flux, microscopie électronique, tests de sécrétion, caryotype et biologie moléculaire)

Monoclonal B-cell lymphocytosis: asymptomatic condition or pretumoral stage

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Machine learning identification of specific changes in myeloid cell phenotype during bloodstream infections

The early identification of bacteremia is critical for ensuring appropriate treatment of nosocomial infections in intensive care unit (ICU) patients. The aim of this study was to use flow cytometric data of myeloid cells as a biomarker of bloodstream infection (BSI). An eight-color antibody panel was used to identify seven monocyte and two dendritic cell subsets. In the learning cohort, immunophenotyping was applied to (1) control subjects, (2) postoperative heart surgery patients, as a model of noninfectious inflammatory responses, and (3) blood culture-positive patients. Of the complex changes in the myeloid cell phenotype, a decrease in myeloid and plasmacytoid dendritic cell numbers, increase in CD14(+)CD16(+) inflammatory monocyte numbers, and upregulation of neutrophils CD64 and CD123 expression were prominent in BSI patients. An extreme gradient boosting (XGBoost) algorithm called the “infection detection and ranging score” (iDAR), ranging from 0 to 100, was developed to identify infection-specific changes in 101 phenotypic variables related to neutrophils, monocytes and dendritic cells. The tenfold cross-validation achieved an area under the receiver operating characteristic (AUROC) of 0.988 (95% CI 0.985–1) for the detection of bacteremic patients. In an out-of-sample, in-house validation, iDAR achieved an AUROC of 0.85 (95% CI 0.71–0.98) in differentiating localized from bloodstream infection and 0.95 (95% CI 0.89–1) in discriminating infected from noninfected ICU patients. In conclusion, a machine learning approach was used to translate the changes in myeloid cell phenotype in response to infection into a score that could identify bacteremia with high specificity in ICU patients

Platelet-rich plasma and tendons healing: rat model

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Tendon lesion and VEGF-111 injection

Introduction: Tendon lesion is one of the most frequent pathology in sports and by physical workers. This pathology often becomes chronic. For this reason, it is of interest to develop new treatments. Injection of platelet-rich plasma (PRP) seems to be a promising one by releasing growth factors (GF) locally. Among all the GF released by activated platelets, the vascular endothelial growth factor-A (VEGF-A) is known to induce positive effects on vascular function and angiogenesis, and could be implicated in the healing process of tendons. Recently, a novel VEGF-A isoform was identified, the VEGF-111, a biologically active and proteolysis-resistant VEGF-A isoform, also known to present beneficial effects on ischemic diseases. This prompted us to evaluate whether VEGF-111 would have a therapeutic interest within the framework of the tendon pathology. Methods: 60 Rats were divided into 2 groups: A: control (no injection), B: VEGF-111 treatment. A 5mm defect was surgically induced in rat Achilles tendon after resection of plantaris tendon. Rats received a local injection of VEGF-111 (100ng) in situ after the surgery and were placed in their cages without immobilization. After 5, 15 and 30 days, the traumatized Achilles tendons of 10 rats of both groups were removed and dissected during their healing process. Immediately after sampling, tendons were submitted to a biomechanical tensile test up to rupture, using a “Cryo-jaw”. Rats were then euthanized. Statistical analyses were made with an ANOVA. Values are significant when p-value is below 0.05. Results: Our results showed that the developed force necessary to induce tendon rupture during biomechanical tensile test was greater for tendons which had received an injection of 100ng of VEGF-111. These results were already noticed from day 5 onwards. The ratio between force and weight increased with time in both groups, but this ratio was greater for tendons which had been submitted to an injection of VEGF111. The surface area of the section of the tendons increased between 5 and 15 days followed by a stabilization. After 30 days, sections in both groups were similar. Thus, the constraint was similar after 5 and 15 days but was better for VEGF111 group after one month. Discussion - Conclusion: This experimentation has shown that a 100ng injection of VEGF-111 stimulated tendon healing process as suggested by the increased force needed to break tendons during its healing process and the increased of constraint in comparison with the control group. Other experimentations with different concentration of VEGF111 are now in process. Acknowledgement : This experimentation was partially financed by “Standard de Liège 2007” and “Lejeune-Lechien 2008” grants

Platelet-rich plasma to treat jumper’s knee: preliminary results

peer reviewedIntroduction: Tendinopathies, especially jumper’s knee, often remain rebel to conservative treatments. Several experimental studies have shown the healing properties of platelet and their growth factors. Researches have specifically demonstrated the platelets action as mediator and/or enhancer of tissue healing. The aim of our study was to investigate the effect of 1 injection of PRP in patients suffering from chronic jumper’s knee. Our protocol was approved by Ethic Committee of University and University Hospital of Liège. Methods: Patients performed imaging (US and MRI) and functional assessments, and a clinical examination using an algometer, before treatment and 6 weeks after PRP treatment. They were also invited to answer to questionnaire relative to pain and functional status. PRP was obtained from autologous blood using an apheresis system (COM.TEC, Fresenius). The injection of 6mL of PRP was realised without local anaesthesia into the proximal insertion of the patellar tendon. A 48h rest-time was recommended after infiltration. Afterwards, a submaximal eccentric reeducation was initiated 1 week after infiltration 3 times a week during 5 weeks. In case of pain, anti-inflammatory drugs were prohibited and patient were encouraged to take class I or II painbrakers. Results: At this time, 10 patients with jumper’s knee were included in our study. Pre-injection tests revealed pain of the upper part of the patellar tendon just below the patella, associated with loss of function. Imaging exams confirmed diagnosis. Six weeks post-injection, the clinical status was improved in all patients, with a significant decrease of algo-functional scores. The pain reported during functional assessments was decreased (in particular for the eccentric actions), yet no significant improvement of physical performances was observed. We found no significant differences between imaging exams before and 6 weeks after PRP injection. Conclusion: One in situ injection of PRP clinically improved patients with jumper’s knee 6 weeks after treatment. All the 10 patients reported a decrease of pain during day-life and through physical activities. However nor functional performances neither imaging were improved

Injection de concentrés plaquettaires et régénération tendineuse : modèle animal

peer reviewedIntroduction : La régénération tendineuse en traumatologie du sport demeure un processus actuellement difficile à gérer et de nouvelles voies thérapeutiques sont en cours d’exploration. La littérature récente fait état d’effets bénéfiques sur la régénération tendineuse de concentrés plaquettaires (platelet-rich plasma ou PRP), administrés in situ, dus au relargage de facteurs de croissance par activation des plaquettes et à leur activité stimulante au cours de la cicatrisation. Dès lors, nous avons souhaité tester l’effet bénéfique de ce traitement sur des rats préalablement lésés au niveau de leur tendon d’Achille. Matériel et Méthode : Une section unilatérale du tendon d’Achille a été réalisée chez 60 rats Sprague Dawley adultes. De ces 60 rats, 30 ont subi une cicatrisation naturelle (rats contrôles) et 30 rats ont bénéficié d’une injection in situ de PRP le jour de la lésion. Diverses études biomécaniques, biochimiques et histologiques ont été réalisées sur ces tendons d’Achille en cours de cicatrisation à respectivement J5, J15 et J30 après lésion. Dix rats supplémentaires ont servi de témoins sains (sans lésion tendineuse). L’étude biomécanique appréciait la résistance maximale des tendons à la traction à l’aide de mors type « cryo-jaws ». L’étude histologique évaluait l’évolution cellulaire pendant la phase de cicatrisation. L’analyse transcriptomique étudiait l’expression de gènes codant pour le collagène de type III, les métalloprotéases matricielles (MMP-9) et la ténomoduline (TNMD), ainsi qu’un dosage d’hydroxyproline permettant d’évaluer la quantité de collagène présente dans le tendon au cours de la cicatrisation. Résultats : L’étude biomécanique démontre la meilleure résistance des tendons traités avec du PRP par rapport aux tendons contrôles à J5 (+19%), J15 (+30%) et significativement à J30 (+43%). L’étude histologique suggère qu’une injection de PRP stimule la prolifération cellulaire, favorise l’organisation tissulaire, stimule l’angiogenèse et la réorganisation architectural du collagène. L’étude biochimique ne permet pas d’expliquer les effets bénéfiques puisqu’il n’y a pas de différence dans l’expression des gènes des différentes molécules matricielles (collagène de type III, MMP-9 et TNMD) ni dans la quantité d’hydroxyproline qui s’accroit au cours du temps de la cicatrisation de façon similaire dans les deux groupes. Conclusion : L’injection de PRP améliore et accélère la cicatrisation tendineuse et augmente la résistance aux contraintes mécaniques du tendon en cours de cicatrisation