Anion exchanger 1 (AE1) is a red cell membrane glycoprotein that associates with cytoskeletal protein 4.2 in a complex bridging the cell membrane to the cytoskeleton. Disruption of this linkage results in unstable erythrocytes and hereditary spherocytosis (HS). Three HS mutations (E40K, G130R and P327R) in the cytoplasmic domain of AE1 (cdAE1) result in a decreased level of protein 4.2 in the red cell yet maintain normal amounts of AE1. Biophysical analyses showed the HS mutations had little effect on the structure and conformational stability of the isolated domain. However, the conformation of the cytoplasmic domain of the kidney anion exchanger, lacking the first 65 amino acids including a central -strand, was thermally destabilized relative to cdAE1 and had a more open structure. In transfected human embryonic kidney (HEK)-293 cells the HS mutants had similar expression levels as wild-type AE1, and protein 4.2 expression level was not dependent on the presence of AE1. Protein 4.2 localized to the plasma membrane with wild-type AE1, the HS mutants of AE1, the membrane domain of AE1 and kidney AE1, and to the ER with Southeast Asian ovalocytosis AE1. A fatty acylation mutant of protein 4.2, G2A/C173A, could not localize to the plasma membrane in the absence of AE1. Subcellular fractionation showed wild-type and G2A/C173A protein 4.2 were mostly associated with the cytoskeleton. Co-immunoprecipitation and Ni-NTA pull-down assays revealed impaired binding of protein 4.2 to HS mutants compared to AE1, while the membrane domain of AE1 was unable to bind protein 4.2. These studies show that HS mutations in cdAE1 cause impaired binding of protein 4.2, without causing gross structural changes in the domain. The mutations change the binding surface on cdAE1 by the introduction of positive charges into an otherwise acidic domain. This binding impairment may render protein 4.2 more susceptible to degradation or loss during red cell development.

Stem and progenitor cell fate (self-renewal, proliferation, survival, differentiation) is tightly controlled by niche factors and the interplay of these factors is particularly important to comprehend for the development of stem cell therapies. During erythropoiesis, erythroid progenitors at the colony forming unit-erythroid (CFU-E) stage are responsive to both stem cell factor (SCF) and erythropoietin (EPO); however, the joint action of SCF and EPO in these cells and the underlying mechanisms remain to be defined. In this study, quantitative data on the activation of signaling pathways and gene expression profiles provided definitive evidence for two parallel but complementary mechanisms that resulted in enhanced generation of red blood cells from mouse bone marrow-derived CFU-E culture in the presence of SCF and EPO. First, SCF and EPO signaling intersected within the extracellular signal-regulated kinase (ERK) pathway and the sustained ERK activation was required for the maximal changes in the expression levels of genes that are involved in the proliferation and survival of CFU-Es. Second, the apparent competition between SCF and EPO in regulating c-Kit expression was found to have a dramatic impact on the terminal differentiation of CFU-Es. The latter mechanism was, for the first time, reported in a primary cell system. In addition, a fetal liver-derived conditioned medium further enhanced the survival and proliferation of bone marrow CFU-Es in the presence of SCF and EPO by not only increasing the ERK signaling duration but also, the amplitude. The agents present in the conditioned media possess significant clinical potential to stimulate erythropoiesis both in vivo and in vitro. In conclusion, our study has provided novel insights into the mechanisms by which combinations of niche factors control the fate of erythroid progenitors at a unique transitional stage and highlighted the important role of the ERK signaling dynamics in adult erythropoiesis.

Stem and progenitor cell fate (self-renewal, proliferation, survival, differentiation) is tightly controlled by niche factors and the interplay of these factors is particularly important to comprehend for the development of stem cell therapies. During erythropoiesis, erythroid progenitors at the colony forming unit-erythroid (CFU-E) stage are responsive to both stem cell factor (SCF) and erythropoietin (EPO); however, the joint action of SCF and EPO in these cells and the underlying mechanisms remain to be defined. In this study, quantitative data on the activation of signaling pathways and gene expression profiles provided definitive evidence for two parallel but complementary mechanisms that resulted in enhanced generation of red blood cells from mouse bone marrow-derived CFU-E culture in the presence of SCF and EPO. First, SCF and EPO signaling intersected within the extracellular signal-regulated kinase (ERK) pathway and the sustained ERK activation was required for the maximal changes in the expression levels of genes that are involved in the proliferation and survival of CFU-Es. Second, the apparent competition between SCF and EPO in regulating c-Kit expression was found to have a dramatic impact on the terminal differentiation of CFU-Es. The latter mechanism was, for the first time, reported in a primary cell system. In addition, a fetal liver-derived conditioned medium further enhanced the survival and proliferation of bone marrow CFU-Es in the presence of SCF and EPO by not only increasing the ERK signaling duration but also, the amplitude. The agents present in the conditioned media possess significant clinical potential to stimulate erythropoiesis both in vivo and in vitro. In conclusion, our study has provided novel insights into the mechanisms by which combinations of niche factors control the fate of erythroid progenitors at a unique transitional stage and highlighted the important role of the ERK signaling dynamics in adult erythropoiesis.

Anion exchanger 1 (AE1) is a red cell membrane glycoprotein that associates with cytoskeletal protein 4.2 in a complex bridging the cell membrane to the cytoskeleton. Disruption of this linkage results in unstable erythrocytes and hereditary spherocytosis (HS). Three HS mutations (E40K, G130R and P327R) in the cytoplasmic domain of AE1 (cdAE1) result in a decreased level of protein 4.2 in the red cell yet maintain normal amounts of AE1. Biophysical analyses showed the HS mutations had little effect on the structure and conformational stability of the isolated domain. However, the conformation of the cytoplasmic domain of the kidney anion exchanger, lacking the first 65 amino acids including a central -strand, was thermally destabilized relative to cdAE1 and had a more open structure. In transfected human embryonic kidney (HEK)-293 cells the HS mutants had similar expression levels as wild-type AE1, and protein 4.2 expression level was not dependent on the presence of AE1. Protein 4.2 localized to the plasma membrane with wild-type AE1, the HS mutants of AE1, the membrane domain of AE1 and kidney AE1, and to the ER with Southeast Asian ovalocytosis AE1. A fatty acylation mutant of protein 4.2, G2A/C173A, could not localize to the plasma membrane in the absence of AE1. Subcellular fractionation showed wild-type and G2A/C173A protein 4.2 were mostly associated with the cytoskeleton. Co-immunoprecipitation and Ni-NTA pull-down assays revealed impaired binding of protein 4.2 to HS mutants compared to AE1, while the membrane domain of AE1 was unable to bind protein 4.2. These studies show that HS mutations in cdAE1 cause impaired binding of protein 4.2, without causing gross structural changes in the domain. The mutations change the binding surface on cdAE1 by the introduction of positive charges into an otherwise acidic domain. This binding impairment may render protein 4.2 more susceptible to degradation or loss during red cell development.

La microcirculation sanguine est un système constitué de réseaux complexesde vaisseaux sanguins de diamètres micrométriques. C’est le lieu privilégié deséchanges de gaz et de nutriments entre le sang et les tissus.Les écoulements dans ces réseaux sont gouvernés par les propriétés des constituantsdu sang c’est-à-dire des cellules en suspension dans du plasma et plus particulièrementdes globules rouges qui sont les cellules majoritaires dans le sang.Selon les conditions de l’écoulement, les globules rouges, qui sont des particulesdéformables, peuvent présenter différents types de formes et de dynamiques quiinfluencent la rhéologie de la suspension. Les interactions hydrodynamiques entreglobules rouges et avec les parois dans les vaisseaux confinés influencent égalementles écoulements à travers des phénomènes de diffusion mais aussi de structurationdes globules au sein de la suspension. Il a notamment été montré que des couchesde plasma dépourvues de globules rouges près des parois des vaisseaux sanguins induisentune diminution de la viscosité effective de la suspension lorsqu’on diminuele diamètre du vaisseau. Par ailleurs, des structurations en file ont également étéobservées dans la microcirculation sanguine avec des conséquences probables surla rhéologie. Au cours de ces travaux de thèse, nous avons investigué les propriétésrhéologiques de suspensions de globules rouges en micro-écoulement grâce à uneméthode de rhéométrie microfluidique. Nous avons focalisé notre attention sur larelation entre la rhéologie et la structuration de la suspension dans un canal, liéeau confinement ainsi qu’aux régimes dynamiques des globules en écoulement.Dans certains cas pathologiques comme la drépanocytose où les propriétés desglobules rouges peuvent être modifiées, les écoulements dans la microcirculationpeuvent être perturbés et conduire à des crises vaso-occlusives dont les mécanismesphysiques restent mal compris. Nous avons exploré la dynamique de formationd’occlusions et leurs évolutions dans des réseaux de canaux micrométriques modèlesavec des suspensions de globules rouges dont les propriétés ont été modifiées,révélant ainsi une dynamique complexe où l’adhésion et des effets d’obstructionsinterviennent. / Blood microcirculation consists in blood flowing in complex microvessel networks.Gas and nutrient exchanges between blood and tissues occur in these networks.Microcirculatory blood flows are governed by the properties of blood components,mainly red blood cells suspended in plasma. Red blood cells are deformableparticles which can exibit different shapes and motion dynamics that influence therheology. Hydrodynamic interactions between red blood cells and with walls of theconfined channels lead to diffusion and structuration in the suspension that alsoaffects the rheology. Plasma cell-free layers near walls observed in the microcirculationinduce a decrease of the effective viscosity with decreasing vessel diameter.Other types of structuration like layering of red blood cells have been observed inthe microcirculation with possible rheological consequences. In the present work,we investigated the rheology of confined red blood cell suspensions and focusedon the link between rheology and structuration of the suspension thanks to amicrofluidic viscosimeter.The sickle cell disease which modifies the properties of red blood cells leadsto flow disorders with the formation of occlusions in the narrow capillaries ofthe microcirculation. We explored the formation and the evolution of occlusionsin simplified networks of microchannels when properties of red blood cells aremodified, revealing complex dynamics where adhesion and jamming effect occur.

Introdução: O Red blood cell distribution width (RDW) é um preditor de mortalidade em pacientes criticamente enfermos. A associação do RDW na alta da UTI com o risco de readmissão à UTI não é conhecida. Nós fizemos este estudo com o objetivo de investigar a associação entre a presença de anisocitose na alta da UTI e o risco de readmissão à UTI ou óbito inesperado na enfermaria. Métodos: Estudo de coorte retrospectivo que incluiu 813 pacientes com alta da UTI para a enfermaria em um hospital terciário de Porto Alegre, Brasil. A variável de interesse foi o RDW coletado no momento da alta da UTI. Anisocitose foi definida como RDW > 16%. Desfechos de interesse foram readmissão à UTI, óbito inesperado na enfermaria e óbito hospitalar. Hazard ratios (HR) foram estimadas usando o Modelo de Riscos proporcionais de Cox. Variáveis com P < 0.1 na análise univariada foram incluídas na análise multivariada para ajuste. Resultados: Anisocitose na alta da UTI está independentemente associada com readmissão à UTI ou óbito inesperado na enfermaria (HR: 1,682; IC 95% 1,219 – 2,322; P = 0,002). Outras variáveis associadas com este desfecho foram: idade, escore Sequential Organ Failure Assessment (SOFA) na alta da UTI e traqueostomia. Resultados significativos semelhantes foram obtidos após exclusão dos óbitos inesperados na enfermaria (HR: 2,031; IC 95% 1,428 – 2,889; P< 0,001) e para óbito hospitalar (HR: 1,716; IC 95% 1,141 – 2,580; P = 0,01). Conclusões: Anisocitose no momento da alta da UTI está independentemente associada com readmissão à UTI e óbito hospitalar. / Introduction: Red blood cell distribution width (RDW) is a predictor of mortality in critically ill patients. The relationship between the RDW at ICU discharge and the risk of ICU readmission is unknown. The purpose of this study was to investigate the association between the presence of anisocytosis at ICU discharge and the risk of ICU readmission or unexpected death in the ward. Methods: This retrospective cohort study included 813 patients discharged alive from the ICU to the ward in a tertiary hospital in Porto Alegre, Brazil. The target variable was the RDW collected at the time of ICU discharge. Anisocytosis was defined as an RDW > 16%. Outcomes of interest included readmission to the ICU, unexpected death in the ward and in-hospital death. Hazard ratios (HR) were estimated using the Cox proportional hazards model. Variables with a value of P < 0.1 in the univariate analysis were included in the multivariate analysis for adjustment. Results: Anisocytosis at ICU discharge was independently associated with readmission to the ICU or unexpected death in the ward (HR: 1.682; 95% CI 1.219-2.322; P = 0.002). Other variables associated with this outcome included age, Sequential Organ Failure Assessment (SOFA) score at ICU discharge and tracheostomy. Similar significant results were obtained after the exclusion of unexpected deaths in the ward (HR 2.031; CI 1.428 – 2.889; P < 0.001) and for in-hospital deaths (HR 1.716; 95% CI 1.141-2.580; P = 0.01). Conclusions: Anisocytosis at ICU discharge is independently associated with ICU readmission and in-hospital death.

Introdução: As transfusões de sangue e as Reações transfusionais (RT) têm tido grande destaque nas discussões e estudos da hemoterapia atual, devido a necessidade e relevância para a prática transfusional e na busca em qualificar as transfusões e refinar a classificação das RT. As reações transfusionais febris não hemolíticas (RTFNH) apresentam um crescente no número de notificações e despertam a necessidade de mais estudos. Durante a estocagem dos hemocomponentes, ocorrem uma série de alterações morfológicas, aumento de potássio (K+) extracelular, hemólise e aumento de hemoglobina (Hb) sobrenadante. Analisar a qualidade e viabilidade do hemocomponente pode nos levar a verificar os fatores preditores de uma RT, procurando minimizar os riscos e selecionar um hemocomponente de melhor qualidade ao paciente. Objetivos: Avaliar potenciais fatores etiológicos na precipitação das RTFNH por meio da mensuração na concentração de sódio (Na+) e K+ no sobrenadante, a contagem leucocitária por mcL, o cultural e o Hematócrito (Ht) e Hb da bolsa de concentrado de hemácias (CH) envolvidas, comparando estes parâmetros em relação a um grupo controle de bolsas de CH. Analisar e comparar o perfil dos pacientes envolvidos com a RTFNH e do grupo controle e, estimar a frequência de culturais coletados positivos e os germes envolvidos. Metodologia: Estudo de caso-controle com seleção de amostras a partir de notificações de suspeita de RTFNH ao Serviço de Hemoterapia de um Hospital Universitário de Porto Alegre - RS, no período de setembro de 2015 a setembro de 2016. O grupo controle foi selecionado a partir da mesma população de bolsas, sendo pareadas por tipagem sanguínea e data de vencimento do hemocomponente, numa proporção de 1:2,1. Resultados: o total incluído foi de 124 bolsas, sendo 39(30,5%) do grupo RT e 85(69,5%) do grupo controle, onde uma série de variáveis foram avaliadas. A média de dias de estocagem das bolsas foi de 10,7(DP=6,7) dias, sendo que no grupo RT 12,1(DP=8,1), foi significativamente maior que no grupo controle 10(DP=5,8) com (P=0,037). Também quando avaliamos as dosagens de Ht as médias verificadas foram de 68,3(DP=7,27), sendo no grupo RT 71(DP=81) e 67(DP=6,5) no grupo controle e, na comparação dos grupos, observamos um P<0,001. Dessa forma, a cada dia a mais de estocagem e, a cada ponto a mais no HT da bolsa, há um aumento na chance de aparecimento de RTFNH. Conclusões: a lesão de estocagem é uma temática importante no momento da oferta de hemocomponentes ao paciente, principalmente aos pacientes em tratamento oncológico de tumores sólidos. A avaliação do HT e do tempo de estocagem da bolsa demonstraram ter relevância estatística e clínica na predição de aparecimento de RTFNH. O manejo de estoque adequado para poder haver essa oferta se faz necessário. Novos estudos serão necessários para verificarmos os mecanismos desencadeantes da RTFNH comparado com o Ht da bolsa e, também estudos relacionados à utilização de pré medicação nas transfusões. / Introduction: Blood transfusions and the transfusion reactions (TR) have had great emphasis in current hemotherapy discussions and studies, due to its importance in transfusion practice and with the aim of qualifying the transfusions and refining TR classifications. The non-hemolytic febrile transfusion reaction (NHFTR) show an increasing number of notifications and arouse the necessity for further studies. During the storage of blood products a series of morphologic alterations occur, such as extracellular potassium (K+) increase, hemolysis and supernatant Hemoglobin (Hb) increase. Analyzing the blood product quality and availability may lead us to verifying predictive factors of a TR, seeking to minimize the risks and select a blood product of a superior quality for the patient. Objective: Evaluate potential etiological factors in the NHFTR precipitation through sodium (Na+) concentration measurement and K+ in the supernatant, the leukocyte count by mcL, the cultural and the Hematocrit (Ht),and Hb of erythrocyte concentrate bag (EC) involved, comparing those parameters in relation to a control group of EC blood bags. Analyze and compare the profile of the patients involved with a NHFTR to the control group and estimate the frequency of positive cultures collected and the germs involved. Methodology: Case-control study with sampling selections from a notification of NHFTR suspicion at a Hemotherapy Service in a College Hospital in Porto Alegre, RS, during the period from September 2015 to September 2016, where the control-group was selected from the same blood bag population, being grouped by blood type and blood product expiry date, in proportion 1:2.1. Results: Were studied 124 blood bags, being 39(39,5%) from the TR group and 85(69,5%) from the control group, where a series of invariables were evaluated. The mean of blood bag storage was 8.5 days, 10,7(PD=6,7) in the TR group and 10(DP=5,8) in the control group, and when compared they showed a P=0.037. Moreover, when we analyzed the Ht dosage, it was verified an mean of 68,3(DP=7,27), in the TR group and 71(DP=81), 67(DP=6,5) in the control group and, comparing both groups, we observed a P=<0.001. Therefore, with each additional storage day and, with each additional point in the Ht bool bag, the chance of NHFTR appearance increases. Conclusions: Storage injury is an important topic at the moment of the offer of blood components to the patient, especially to the ones with ongoing oncological treatments for solid tumors. The HT evaluation and the storage time of the blood bag demonstrate clinical and statistical relevance in the prediction of NHFTR appearance. The management of adequate storage is fundamental for the offer’s availability. Further studies are needed to verify the triggering mechanisms of NHFTR compared to the Ht of the bag, as well as studies associated with the use of premedication in transfusions.

Blood is a complex suspension of deformable particles, red blood cells, which exhibits a sophisticated dynamics when flowing in the microvasculature. Most of these complex phenomena, non-linear rheology, structuration of the suspension, heterogeneities of the hematocrit distribution, are directly connected to the rich microscopic dynamics of individual red blood cells, and their hydrodynamics interactions. We investigate a few aspects of the dynamics of red blood cells and giant vesicles - a simple model for RBCs. A study on the dynamics of very deflated vesicles, with shapes similar to those of red blood cells, shows that these objects which haven't received a lot of attention so far can exhibit richer than expected dynamics. We then mainly focus on the still unexplored problem of hydrodynamic interactions between vesicles or red blood cells and their consequences at the scale of the suspension. An experimental study of the interaction of two identical vesicles in shear flow shows that there is a net repulsion between the cells that leads to an increase of the distance between vesicles in a suspension. Scaling arguments are proposed for this interaction and a comparison with numerical results is performed and a quantitative estimation of a shear induced diffusion coefficient obtained by averaging the results for pair interactions is found. Finally, we investigate the diffusion of a cloud of red blood cells in Poiseuille flow in order to directly determine diffusion coefficients. The experiment shows that the cloud widens when traveling along the channel with a power law behaviour indicating sub-diffusion. This effect is confirmed by a theoretical analysis of a few limit cases. / Blood is a complex suspension of deformable particles, red blood cells, which exhibits a sophisticated dynamics when flowing in the microvasculature. Most of these complex phenomena, non-linear rheology, structuration of the suspension, heterogeneities of the hematocrit distribution, are directly connected to the rich microscopic dynamics of individual red blood cells, and their hydrodynamics interactions. We investigate a few aspects of the dynamics of red blood cells and giant vesicles - a simple model for RBCs. A study on the dynamics of very deflated vesicles, with shapes similar to those of red blood cells, shows that these objects which haven't received a lot of attention so far can exhibit richer than expected dynamics. We then mainly focus on the still unexplored problem of hydrodynamic interactions between vesicles or red blood cells and their consequences at the scale of the suspension. An experimental study of the interaction of two identical vesicles in shear flow shows that there is a net repulsion between the cells that leads to an increase of the distance between vesicles in a suspension. Scaling arguments are proposed for this interaction and a comparison with numerical results is performed and a quantitative estimation of a shear induced diffusion coefficient obtained by averaging the results for pair interactions is found. Finally, we investigate the diffusion of a cloud of red blood cells in Poiseuille flow in order to directly determine diffusion coefficients. The experiment shows that the cloud widens when traveling along the channel with a power law behaviour indicating sub-diffusion. This effect is confirmed by a theoretical analysis of a few limit cases.

Les vésicules sont des bicouches fermées de molécules tensioactives, remplies de liquide, à l'intérieur d'un autre liquide. Leur taille peut être comprise entre dix et 100 microns : elles sont alors dites géantes. Nous nous intéressons à la dynamique de deux de ces objets dans un cisaillement simple, c'est à dire l'écoulement d'un liquide situé entre deux plaques planes se translatant l'une par rapport à l'autre à vitesse et distance constante. Nous commençons par une étude asymptotique, pour des vésicules quasi-sphériques en interaction lointaine. Nous utilisons ensuite un code de calcul basé sur la méthode des éléments de frontière pour étudier le cas de vésicules moins sphériques et plus proches, et comparons les résultats obtenus avec des expériences. Nous présentons enfin comment cette étude peut être utilisée pour prédire certaines propriétés de diffusion d'une suspension de vésicules, dans le régime semi-dilué, où seul le détail des interactions à deux corps est considéré. / Vesicles are closed bilayers of tensioactive molecules, filled with liquid, inside another liquid. Their size can be between 10 and 100 microns : in this case, they are called giant vesicles. We study the dynamic of two of these objects in a simple shear flow, which is the one of a liquid sheared between two walls translating with respect to each other at a constant speed and distance. We begin by an asymptotic study, for quasispherical vesicles in the far field interacting regime. We then use a numerical code based on the boundary element method to study the case of less spherical and closer vesicles, and compare our results with experiments. We finish by presenting how this study can be used to predict some diffusing properties of a sheared suspension of vesicles, in the semidilute regime, where only the details of two body interactions are considered.

Introdução: O Red blood cell distribution width (RDW) é um preditor de mortalidade em pacientes criticamente enfermos. A associação do RDW na alta da UTI com o risco de readmissão à UTI não é conhecida. Nós fizemos este estudo com o objetivo de investigar a associação entre a presença de anisocitose na alta da UTI e o risco de readmissão à UTI ou óbito inesperado na enfermaria. Métodos: Estudo de coorte retrospectivo que incluiu 813 pacientes com alta da UTI para a enfermaria em um hospital terciário de Porto Alegre, Brasil. A variável de interesse foi o RDW coletado no momento da alta da UTI. Anisocitose foi definida como RDW > 16%. Desfechos de interesse foram readmissão à UTI, óbito inesperado na enfermaria e óbito hospitalar. Hazard ratios (HR) foram estimadas usando o Modelo de Riscos proporcionais de Cox. Variáveis com P < 0.1 na análise univariada foram incluídas na análise multivariada para ajuste. Resultados: Anisocitose na alta da UTI está independentemente associada com readmissão à UTI ou óbito inesperado na enfermaria (HR: 1,682; IC 95% 1,219 – 2,322; P = 0,002). Outras variáveis associadas com este desfecho foram: idade, escore Sequential Organ Failure Assessment (SOFA) na alta da UTI e traqueostomia. Resultados significativos semelhantes foram obtidos após exclusão dos óbitos inesperados na enfermaria (HR: 2,031; IC 95% 1,428 – 2,889; P< 0,001) e para óbito hospitalar (HR: 1,716; IC 95% 1,141 – 2,580; P = 0,01). Conclusões: Anisocitose no momento da alta da UTI está independentemente associada com readmissão à UTI e óbito hospitalar. / Introduction: Red blood cell distribution width (RDW) is a predictor of mortality in critically ill patients. The relationship between the RDW at ICU discharge and the risk of ICU readmission is unknown. The purpose of this study was to investigate the association between the presence of anisocytosis at ICU discharge and the risk of ICU readmission or unexpected death in the ward. Methods: This retrospective cohort study included 813 patients discharged alive from the ICU to the ward in a tertiary hospital in Porto Alegre, Brazil. The target variable was the RDW collected at the time of ICU discharge. Anisocytosis was defined as an RDW > 16%. Outcomes of interest included readmission to the ICU, unexpected death in the ward and in-hospital death. Hazard ratios (HR) were estimated using the Cox proportional hazards model. Variables with a value of P < 0.1 in the univariate analysis were included in the multivariate analysis for adjustment. Results: Anisocytosis at ICU discharge was independently associated with readmission to the ICU or unexpected death in the ward (HR: 1.682; 95% CI 1.219-2.322; P = 0.002). Other variables associated with this outcome included age, Sequential Organ Failure Assessment (SOFA) score at ICU discharge and tracheostomy. Similar significant results were obtained after the exclusion of unexpected deaths in the ward (HR 2.031; CI 1.428 – 2.889; P < 0.001) and for in-hospital deaths (HR 1.716; 95% CI 1.141-2.580; P = 0.01). Conclusions: Anisocytosis at ICU discharge is independently associated with ICU readmission and in-hospital death.