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Transfusion of washed platelet concentrates (W-PC) is recommended for some patients, such as those who have had previous severe allergic transfusion reactions. However, we still lack a standardised method for preparing these products. Here, we assessed the effect of a manual washing procedure on in vitro platelet quality and on the transfusion efficacy of W-PCs.Buffy coat-derived W-PC in Composol solution were prepared by one-step centrifugation. Platelet activation and function were evaluated before and after washing by means of: (i) CD62 expression by flow cytometry; (ii) platelet aggregation (LTA); and (iii) the VerifyNowPlatelet recovery in W-PC was 84.8±5.4%. Washing slightly increased platelet activation in W-PC vs pre-washed samples (% CD62+ platelets 23.6±7 vs 14.8±1; p=0.03). As compared to prewash samples, platelet reactivity of W-PC as measured by VerifyNowWe have set up a simple method to obtain buffy-coat-derived W-PC, which has minor effects on in vitro platelet quality and transfusion effectiveness. This procedure can be easily implemented in transfusion centres for on-demand preparation of washed platelets.

Desde la primera transfusión directa realizada mediante una anastomosis entre vasos sanguíneos del receptor y del donante en 1914, los avances en el mundo de la medicina transfusional han sido numerosos e imprescindibles para el progreso de la medicina, como hoy la conocemos. A lo largo de las siguientes páginas realizaremos una breve revisión de la producción, almacenamiento y lesión asociada al almacenamiento de los concentrados de plaquetas, así como de la indicación transfusional y efectos adversos relacionados con la transfusión de éstos. También describiremos a continuación nuestra aportación a este campo. En nuestro primer estudio hemos evaluado la calidad in vitro de los concentrados de plaquetas de buffy coat leucodepleccionados preparados por dos dispositivos automatizados OrbiSac o TACSI. A lo largo de un almacenamiento estándar, analizamos en los días 1, 5 y 7, las diferencias en el contaje celular, parámetros metabólicos, funcionalidad y activación plaquetaria, y moléculas pro-inflamatorias. Ambos productos plaquetarios cumplieron con los estándares de los productos plaquetarios en relación con el contenido de plaquetas y leucocitos. La evaluación in vitro del metabolismo plaquetario, funcionalidad, respuesta al choque osmótico o el estudio de agregación plaquetaria, fue similar entre ambos productos. Sin embargo, el sistema OrbiSac indujo un incremento transitorio en la activación de plaquetas y una mayor liberación de sustancias proinflamatorias (sCD62P, RANTES y sCD40L) en el día de la preparación de los concentrados de plaquetas. En nuestro segundo estudio hemos comparado la eficacia transfusional de los concentrados de plaquetas, preparados por el método de plasma rico en plaquetas y los obtenidos con el método de buffy coat, en una cohorte de pacientes sometidos a trasplante alogénico de progenitores hematopoyéticos. La transfusión de concentrados de plaquetas producidos por el método buffy coat se asoció con un mayor incremento del recuento plaquetario a las 24 horas, y supuso una menor exposición a donantes con cada transfusión. Identificamos como factores predictivos de un menor rendimiento transfusional, el diagnóstico diferente al de leucemia aguda, la presencia de esplenomegalia, la profilaxis de enfermedad injerto contra huésped diferente de ciclosporina A y metotrexato, y la transfusión de concentrados de plaquetas producidos por el método de plasma rico en plaquetas. A pesar del mayor incremento en los recuentos plaquetarios en el grupo de pacientes transfundidos con concentrados de plaquetas buffy coat, no se objetivó una disminución de los eventos hemorrágicos. Por último, en nuestro tercer estudio hemos implementado un protocolo simple y eficaz para el lavado de concentrados de plaquetas buffy coat con solución aditiva. La transfusión de concentrados de plaquetas lavados está indicada en pacientes muy específicos, como aquellos con reacciones transfusionales graves o con deficiencia de inmunoglobulina A o haptoglobina. Nuestro procedimiento supone la pérdida de alrededor del 15% del total de las plaquetas. In vitro se objetivó en estas plaquetas lavadas un discreto aumento de marcadores de activación (P-selectina) o la disminución de la reactividad plaquetaria medida con el test VerifyNow® cuando se utiliza un agonista poco potente como ADP. La reactividad plaquetaria medida por transmisión de luz simple o utilizando un agonista potente, como TRAP en el test de VerifyNow® no se afectó. La eficacia in vivo de estos concentrados de plaquetas lavados fue investigada en una cohorte de 11 pacientes onco-hematológicos seleccionados por la previsión de que necesitarían la transfusión de 2 concentrados de plaquetas en un breve intervalo. La eficacia transfusional determinada por el incremento del recuento plaquetario corregido a la hora y 24 horas de la transfusión no mostró diferencias estadísticas significativas. Más relevante aún fue la observación de que la transfusión de estos concentrados de plaquetas lavados no se asoció con un incremento de episodios hemorrágicos. Since the first direct transfusion through an anastomosis between recipient and donor blood vessels in 1914, advances in the world of transfusional medicine have been extensive and essential for the progress of medicine as we know it today. Throughout the following pages we will briefly review the production, storage and lesion of platelets concentrates, as well as the indication and adverse effects related to platelets transfusion. We will also describe our contribution to this field below. In our first study, we evaluated the in vitro quality of buffy coat leucodepleted platelet concentrates prepared by two automated OrbiSac or TACSI devices. Throughout a standard storage, differences in cell count, metabolic parameters, platelet function and activation, and proinflammatory molecules were analyzed on days 1, 5, and 7. Both platelet products met the standards in terms of platelet and leucocyte content. The in vitro evaluation of platelet metabolism, functionality, hypotonic shock response or platelet aggregation study, was similar between both products. However, the OrbiSac system induced a transient increase in platelet activation and a greater release of proinflammatory substances (sCD62P, RANTES and sCD40L) on the day of preparation of the platelet concentrates. In our second study we compared the transfusion efficacy of platelet concentrates prepared by the platelet-rich plasma method and those obtained by the buffy coat method, in a cohort of patients undergoing allogeneic haematopoietic stem cell transplantation. Transfusion of platelet concentrates produced by the buffy coat method was associated with a greater 24 hours post-transfusion corrected count increment, and resulted in less donor exposure in each single transfusion. As independent predictors of poor platelets transfusion response, we identified the diagnosis other than acute leukemia, splenomegaly, prophylaxis of graft-versus-host disease other than cyclosporin A and methotrexate, and transfusion of platelet concentrates produced by the platelet-rich plasma method. Despite the largest increase in platelet counts, the transfusion of buffy coat platelet concentrates provides no significant benefit regarding bleeding outcome. Finally, in our third study we have implemented a simple and effective protocol for the washing of buffy coat platelet concentrate with additive solution. Transfusion of washed platelet concentrates is indicated in specific patients, such as those suffering from severe transfusion reactions or immunoglobulin A or haptoglobin deficiency. Our procedure resulted in the loss of about 15% of total platelets. In vitro, a minimal increase in activation markers (P-selectin) or a decrease in platelet reactivity measured with the VerifyNow® test when using a weak agonist such as ADP was observed in these washed platelets. Platelet reactivity measured by light transmission agrregometry or using a powerful agonist such as TRAP in the VerifyNow® test was not affected. The in vivo efficacy of the washed platelets concentrates was investigated in a cohort of 11 onco-haematological patients who were expected to receive at least two platelet transfusion in a short period of time. The transfusion efficacy as determined by the increase in the one hour and 24 hour platelet increment showed, no statistically significant difference. Remarkably, the transfusion of these washed platelets concentrates was not associated with an increase in bleeding episodes.

Objectives: Whole blood-derived platelet concentrates can be obtained by the platelet-rich plasma (PRP-PCs) or the buffy-coat (BC-PCs) method. Few studies have shown that BC-PCs display lower in vitro platelet activation, but scarce information exists regarding transfusion efficacy. We have performed a retrospective study assessing platelet transfusion in patients undergoing allogeneic hematopoietic cell transplantation (AHCT) in our clinic, before and after the implementation of BC-PCs. Methods: We reviewed clinical records corresponding to 70 PRP-PCs and 86 BC-PCs prophylactic transfusions, which were performed to 55 AHCT patients. Transfusion efficacy was assessed by the 24-h post-transfusion corrected count increment (24-h CCI) and bleeding events. Clinical factors affecting transfusion outcome were also investigated. Results: Clinical characteristics and the total number of platelet transfusions were similar among groups. Mean donor exposure was 5.8 and 5.0 in each single PRP-PCs and BC-PCs transfusion, respectively (p p p = 0.004), splenomegaly (HR 8.75; 95% CI 2.77–27.60; p p = 0.004) and PRP-PCs transfusion (HR 4.54; 95% CI 1.72–12.01; p = 0.002). There were no differences between both groups regarding the bleeding events. Conclusion: In the AHCT setting, we hypothesize that BC-PCs transfusion, when compared to PRP-PCs, results in higher CCI and reduced donor exposure, but provides no significant benefit regarding bleeding outcome.