The Glucose transporter 1 (GLUT1) is one of the most abundant proteins within the erythrocyte membrane and is required for glucose and dehydroascorbic acid (Vitamin C precursor) transport. It is widely recognized as a key protein for red cell structure, function, and metabolism. Previous reports highlighted the importance of GLUT1 activity within these uniquely glycolysis-dependent cells, in particular for increasing antioxidant capacity needed to avoid irreversible damage from oxidative stress in humans. However, studies of glucose transporter roles in erythroid cells are complicated by species-specific differences between humans and mice. Here, using CRISPR-mediated gene editing of immortalized erythroblasts and adult CD34+ hematopoietic progenitor cells, we generate committed human erythroid cells completely deficient in expression of GLUT1. We show that absence of GLUT1 does not impede human erythroblast proliferation, differentiation, or enucleation. This work demonstrates for the first-time generation of enucleated human reticulocytes lacking GLUT1. The GLUT1-deficient reticulocytes possess no tangible alterations to membrane composition or deformability in reticulocytes. Metabolomic analyses of GLUT1-deficient reticulocytes reveal hallmarks of reduced glucose import, downregulated metabolic processes and upregulated AMPK-signalling, alongside alterations in antioxidant metabolism, resulting in increased osmotic fragility and metabolic shifts indicative of higher oxidant stress. Despite detectable metabolic changes in GLUT1 deficient reticulocytes, the absence of developmental phenotype, detectable proteomic compensation or impaired deformability comprehensively alters our understanding of the role of GLUT1 in red blood cell structure, function and metabolism. It also provides cell biological evidence supporting clinical consensus that reduced GLUT1 expression does not cause anaemia in GLUT1 deficiency syndrome. Key Points GLUT1 knockout does not affect erythroid differentiation and minimally impacts reticulocyte membrane composition Metabolic adaptation facilitates reticulocyte tolerance of GLUT1 absence

To assess the viability of human red blood cells that have been lyophilized and reconstituted to the hydrated state, we phlebotomized a unit of whole blood from six healthy male volunteers. Their packed red blood cells were lyophilized at -40 degrees C and stored at 4 degrees C. Upon rehydration, recovery of erythrocytes was 85.2 +/- 2.79%. Aliquots of 20 ml were labeled with 51Cr and re-infused into the original donors for red cell survival studies. The red cells retained ABO and Rh identity upon rehydration. There were no adverse clinical affects of re-infusion. The half time of 51Cr disappearance from the circulation was 31 +/- 8.19 days, and there was no evidence of significant splenic sequestration on the day of reinfusion. Red cell indices of the rehydrated erythrocytes were normal, oxyhemoglobin content was 98.58 +/- 1.46%, and P50 was 27.25 +/- 1.84 mmHg. Although deformability was slightly decreased, the osmotic fragility and filterability of the red cells were normal. These data demonstrate that human erythrocytes can be lyophilized and reconstituted to the hydrated state and survive normally in the circulation. Metabolic, osmotic, hematological and rheological function remains intact.

mature red blood cells and plate- lets are exceptions, each lacking a nucleus and its DNA … its life span? Do all of its cells survive and function for its full lifetime? Or do some … systems: form, control, a unity of design and function that favors the survival of the organism

The Red blood cell (RBC) membrane is naturally endowed with a variety of membrane transporters, mainly geared to optimize the respiratory function and to maintain cell homeostasis at minimal metabolic cost. Therefore, to survive within a red blood cell, the malaria parasite must alter the permeability of the host’s plasma membrane by up-regulation of existing carriers or by creation of new permeation pathways (NPP).These pathways, indispensable for parasite growth, could be possible antimalarial targets for selective inhibition, as well as routes for drug delivery. Electrophysiological techniques, such as the patch clamp, are ideal for the study of channels that are permeable to charged solutes, even though the NPP are also used for transport of electroneutral and organic osmolytes in malaria infected RBCs. Red blood cells have proven to be extremely useful as a model system to study the different membrane transport pathways, and there is a plethora of publications aimed at a detailed description of pumps, cotransporters, and specific carriers in the red blood cell membrane. In the cell-attached and excised configurations, Plasmodium falciparum-infected RBCs show a very different pattern of channel activity from uninfected cells. It has been suggested that NPP could be used as therapeutic targets. However, the exact nature of the NPP remains to be resolved; part of the present confusion, due to discrepant results, comes from the lack of background information on the channels