Accumulating evidence suggests that manganese oxide nanoparticles (NPs) show multiple enzyme-mimicking antioxidant activities, which supports their potential in redox-targeting therapeutic strategies for diseases with impaired redox signaling. However, the systemic administration of any NP requires thorough hemocompatibility testing. In this study, we assessed the hemocompatibility of synthesized Mn3O4 NPs, identifying their ability to induce spontaneous hemolysis and eryptosis or impair osmotic fragility. Concentrations of up to 20 mg/L were found to be safe for erythrocytes. Eryptosis assays were shown to be more sensitive than hemolysis and osmotic fragility as markers of hemocompatibility for Mn3O4 NP testing. Flow cytometry- and confocal microscopy-based studies revealed that eryptosis induced by Mn3O4 NPs was accompanied by Ca2+ overload, altered redox homeostasis verified by enhanced intracellular reactive oxygen species (ROS) and reactive nitrogen species (RNS), and a decrease in the lipid order of cell membranes. Furthermore, Mn3O4 NP-induced eryptosis was calpain- and caspase-dependent.

• Keywords
• calcium signaling, cytotoxicity, eryptosis, nanoparticles, oxidative stress, regulated cell death,
• MeSH
• Cell Membrane * metabolism   drug effects   MeSH
• Eryptosis * drug effects   MeSH
• Erythrocytes drug effects   metabolism   MeSH
• Hemolysis drug effects   MeSH
• Calpain * metabolism   MeSH
• Caspases * metabolism   MeSH
• Humans MeSH
• Nanoparticles * chemistry   MeSH
• Oxides * pharmacology   chemistry   MeSH
• Reactive Nitrogen Species * metabolism   MeSH
• Reactive Oxygen Species * metabolism   MeSH
• Manganese Compounds * pharmacology   chemistry   MeSH
• Calcium * metabolism   MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Calpain * MeSH
• Caspases * MeSH
• manganese oxide MeSH Browser
• Oxides * MeSH
• Reactive Nitrogen Species * MeSH
• Reactive Oxygen Species * MeSH
• Manganese Compounds * MeSH
• Calcium * MeSH

Over the recent years, our understanding of the cell death machinery of mature erythrocytes has been greatly expanded. It resulted in the discovery of several regulated cell death (RCD) pathways in red blood cells. Apoptosis (eryptosis) and necroptosis of erythrocytes share certain features with their counterparts in nucleated cells, but they are also critically different in particular details. In this review article, we summarize the cell death subroutines in the erythroid precursors (apoptosis, necroptosis, and ferroptosis) in comparison to mature erythrocytes (eryptosis and erythronecroptosis) to highlight the consequences of organelle clearance and associated loss of multiple components of the cell death machinery upon erythrocyte maturation. Recent advances in understanding the role of erythrocyte RCDs in health and disease have expanded potential clinical applications of these lethal subroutines, emphasizing their contribution to the development of anemia, microthrombosis, and endothelial dysfunction, as well as their role as diagnostic biomarkers and markers of erythrocyte storage-induced lesions. Fas signaling and the functional caspase-8/caspase-3 system are not indispensable for eryptosis, but might be retained in mature erythrocytes to mediate the crosstalk between both erythrocyte-associated RCDs. The ability of erythrocytes to switch between eryptosis and necroptosis suggests that their cell death is not a simple unregulated mechanical disintegration, but a tightly controlled process. This allows investigation of eventual pharmacological interventions aimed at individual cell death subroutines of erythrocytes.

• Keywords
• Apoptosis, Cell death, Ferroptosis, Necroptosis, Red blood cell,
• MeSH
• Apoptosis * MeSH
• Cell Death MeSH
• Eryptosis MeSH
• Erythrocytes * metabolism   cytology   MeSH
• Ferroptosis MeSH
• Humans MeSH
• Necroptosis MeSH
• Signal Transduction * MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Review MeSH