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	<title>alter &#8211; Science</title>
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	<title>alter &#8211; Science</title>
	<link>https://scienmag.com</link>
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		<title>Amyloid beta peptides disrupt oxygen transport in red blood cells, study finds</title>
		<link>https://scienmag.com/amyloid-beta-peptides-disrupt-oxygen-transport-in-red-blood-cells-study-finds/</link>
		
		<dc:creator><![CDATA[Diana Fleming]]></dc:creator>
		<pubDate>Sun, 18 Oct 2026 04:41:56 +0000</pubDate>
				<category><![CDATA[Medicine]]></category>
		<category><![CDATA[alter]]></category>
		<category><![CDATA[Alzheimer's clinical symptoms]]></category>
		<category><![CDATA[Alzheimer's disease]]></category>
		<category><![CDATA[amyloid]]></category>
		<category><![CDATA[amyloid beta peptides]]></category>
		<category><![CDATA[amyloid-beta red blood cell interaction]]></category>
		<category><![CDATA[blood]]></category>
		<category><![CDATA[cells]]></category>
		<category><![CDATA[cerebral hypoxia]]></category>
		<category><![CDATA[function]]></category>
		<category><![CDATA[hemoglobin oxygen affinity]]></category>
		<category><![CDATA[impact of amyloid beta on blood oxygen delivery]]></category>
		<category><![CDATA[molecular mechanism of hypoxia]]></category>
		<category><![CDATA[neurodegeneration and oxygen deficiency]]></category>
		<category><![CDATA[oxygen]]></category>
		<category><![CDATA[oxygen saturation in Alzheimer's patients]]></category>
		<category><![CDATA[oxygen transport disruption]]></category>
		<category><![CDATA[peptides]]></category>
		<category><![CDATA[red blood cells]]></category>
		<category><![CDATA[redox]]></category>
		<category><![CDATA[Scientific Research]]></category>
		<category><![CDATA[status]]></category>
		<category><![CDATA[transport]]></category>
		<guid isPermaLink="false">https://scienmag.com/?p=303864</guid>

					<description><![CDATA[Scientists have uncovered a surprising new way that Alzheimer's disease may starve the brain of oxygen: by hijacking the body's own oxygen delivery system. In a study published in Cell Death Discovery, a team led by Irina Petrushanko and Alexander]]></description>
										<content:encoded><![CDATA[<p>Scientists have uncovered a surprising new way that Alzheimer&#8217;s disease may starve the brain of oxygen: by hijacking the body&#8217;s own oxygen delivery system. In a study published in Cell Death Discovery, a team led by Irina Petrushanko and Alexander Makarov of the Engelhardt Institute of Molecular Biology in Moscow, working with Anna Bogdanova of the University of Zurich, shows that amyloid beta peptides — the notorious protein fragments that accumulate in Alzheimer&#8217;s brains — bind to red blood cells and fundamentally alter how hemoglobin picks up and releases oxygen. The finding offers a concrete molecular mechanism for a clinical mystery that has puzzled physicians for years: patients with Alzheimer&#8217;s disease show reduced cerebral venous oxygen saturation, a deficit that worsens as the disease progresses and correlates with cognitive decline. Until now, the causes of this hypoxia remained unclear.</p>
<p>Red blood cells are far more than passive oxygen containers. Hemoglobin, the tetrameric protein that fills these cells, binds oxygen in the lungs and releases it in tissues, and the affinity with which hemoglobin holds oxygen is finely tuned by the cell&#8217;s internal chemical environment. Petrushanko&#8217;s team reasoned that because red blood cells are the primary carrier of amyloid beta in the bloodstream — and because amyloid loading of these cells increases with both age and Alzheimer&#8217;s disease — the peptides might directly interfere with oxygen transport. The researchers focused on two forms of the peptide: the canonical 42-amino-acid amyloid beta (Aβ42) and a pathological isoform in which the aspartate residue at position 7 has been isomerized (isoAβ42), a spontaneous chemical conversion that accumulates in aged brains and is considered a key pathological factor in Alzheimer&#8217;s disease.</p>
<p>The experiments produced a result that the field had never documented before. When the researchers loaded human red blood cells with elevated amounts of either peptide, hemoglobin&#8217;s oxygen affinity dropped, and the rate at which oxygen was released from the cells slowed down. In practical terms, amyloid-coated red blood cells hold onto oxygen more stubbornly in the lungs and then surrender it more sluggishly in the tissues — precisely the wrong behavior for an organ already struggling to clear metabolic waste and maintain neuronal health. The effect was not a subtle perturbation of a single parameter but a coordinated shift in the cell&#8217;s entire oxygen-handling machinery.</p>
<p>The mechanism traces back to reactive oxygen species, the chemically reactive molecules that red blood cells generate continuously as byproducts of oxygen metabolism. Counterintuitively, the study found that amyloid binding lowered rather than raised the level of ROS inside the cells. This decrease in ROS proved to be the causal link to hemoglobin&#8217;s altered behavior: ROS levels regulate hemoglobin glutathionylation, a post-translational modification in which glutathione — a tripeptide antioxidant — is covalently attached to hemoglobin&#8217;s cysteine residues. Glutathionylation of hemoglobin is known to modulate its oxygen affinity and structural dynamics. When amyloid peptides suppressed ROS, hemoglobin glutathionylation decreased, and the protein&#8217;s alpha-helical content — the coiled structural elements that define its functional conformation — diminished as well. In effect, amyloid peptides chemically remodel hemoglobin from the outside in, using the cell&#8217;s own redox system as the lever.</p>
<p>The two peptide forms diverged in their downstream effects, revealing that the pathological isoform carries additional chemical consequences. While Aβ42 primarily reduced hemoglobin glutathionylation and alpha-helical structure, isoAβ42 went further: it reduced nitric oxide levels inside the cells and altered the heme state of hemoglobin — the iron-containing porphyrin rings that actually bind oxygen. Nitric oxide is a critical regulator of vascular tone and of hemoglobin&#8217;s own conformational transitions, so its depletion adds a second layer of dysfunction. The heme-state alteration suggests that isoAβ42 may directly perturb the oxygen-binding site itself, not merely the protein&#8217;s overall architecture. This distinction matters because isoAβ42 is the form that accumulates preferentially in the aging brain, meaning the most pathological peptide variant may also be the most damaging to oxygen transport.</p>
<p>To pin down the upstream source of the ROS changes, the researchers turned to NADPH oxidase, the membrane-bound enzyme complex that red blood cells use as their principal source of controlled ROS production. When the team inhibited NADPH oxidase pharmacologically, the impact of amyloid beta on ROS levels, on hemoglobin oxygen affinity, and on alpha-helical content was abolished entirely. The conclusion is striking in its simplicity: amyloid peptides impair erythrocyte oxygen affinity primarily by suppressing NADPH oxidase activity. Rather than generating oxidative damage through runaway radical production — the scenario most often assumed in amyloid toxicity — the peptides instead throttle the cell&#8217;s controlled ROS-generating machinery, and it is this throttling that cascades into hemoglobin&#8217;s structural and functional changes.</p>
<p>The team did not stop at isolated cells in a dish. Using a transgenic APP/PS1 mouse model of Alzheimer&#8217;s disease — animals engineered to carry human amyloid precursor protein and presenilin mutations that drive amyloid accumulation — the researchers measured both the amount of Aβ42 on the surface of circulating red blood cells and the level of intracellular ROS. The two quantities were negatively correlated: the more amyloid sat on the cell surface, the lower the ROS inside. This in vivo correlation transforms the cell-culture findings from a laboratory curiosity into a plausible physiological process operating in a living animal model of the disease, and it suggests that the same mechanism could be at work in human patients whose red blood cells become progressively amyloid-loaded with age and disease.</p>
<p>The clinical implications reach back to a measurement that neurologists have documented but struggled to explain. Reduced cerebral venous oxygen saturation in Alzheimer&#8217;s patients — the observation that opened the study — has long been treated as a downstream consequence of reduced cerebral blood flow or metabolic decline. The new work raises the possibility that the blood itself is part of the problem: that amyloid-laden red blood cells, chemically remodeled by the peptides they carry, transport oxygen less efficiently and release it more reluctantly, contributing directly to the tissue hypoxia that accelerates neuronal death. If confirmed in human studies, this mechanism would reframe amyloid beta not solely as a brain-localized toxin but as a circulating agent that compromises the body&#8217;s oxygen logistics, potentially explaining why cognitive decline in Alzheimer&#8217;s tracks so closely with oxygen saturation deficits.</p>
<p>The study also adds red blood cells to the growing list of cell types that amyloid beta subverts through redox manipulation. The finding that NADPH oxidase inhibition abolishes the amyloid effect points to a specific enzymatic target whose pharmacological modulation might protect oxygen transport even in the presence of circulating amyloid. It suggests that therapies aimed at preserving red blood cell function — rather than solely at clearing amyloid from the brain — could complement existing therapeutic strategies. And it hints that the red blood cell, long regarded as a simple oxygen courier, may deserve renewed attention as both a victim and a vector of Alzheimer&#8217;s pathology, carrying the disease&#8217;s molecular signature through every vessel of the body while quietly losing its ability to do the one job it exists to perform.</p>
<p>For a field that has spent decades focused on neurons, plaques, and synapses, the redirection of attention to the bloodstream represents a conceptual expansion with immediate testable consequences. The molecular chain the Moscow and Zurich teams traced — amyloid binding, NADPH oxidase suppression, ROS depletion, reduced hemoglobin glutathionylation, diminished alpha-helical structure, lowered oxygen affinity, slowed oxygen release — is a complete mechanistic pathway from a circulating peptide to a systemic physiological deficit. Each link in that chain is now a potential intervention point, and the negative correlation between surface amyloid and intracellular ROS in the APP/PS1 model provides a measurable biomarker that could be assessed in human cohorts. The possibility that one mechanism underlying reduced blood oxygen saturation in Alzheimer&#8217;s disease has been identified gives the study a significance that extends well beyond the laboratory bench, offering both an explanation for a long-standing clinical observation and a roadmap for future therapeutic exploration.</p>
<p><strong>Subject of Research:</strong> Amyloid β peptides alter redox status and oxygen transport function of red blood cells</p>
<p><strong>Article Title:</strong> Amyloid β peptides alter redox status and oxygen transport function of red blood cells</p>
<p><strong>Article References:</strong> Petrushanko, I. Y., Zaripov, P. I., Kozyreva, P. A., Bogdanova, A. Y., Barkovskaya, V. I., Lisitskii, D. R., Dalina, A. A., Kaluzhny, D. N., Kuleshova, I. D., Strelkova, M. A., Grigorova, I. L., Varshavskaya, K. B., Parshina, E. Y., Bochkova, Z. V., Maksimov, G. V., Indeykina, M. I., Bugrova, A. E., Nikolaev, N. A., Merzlyak, E. M., &#8230; Makarov, A. A. (2026). Amyloid β peptides alter redox status and oxygen transport function of red blood cells. <em>Cell Death Discovery</em>. <a href="https://doi.org/10.1038/s41420-026-03413-3" rel="noopener noreferrer">https://doi.org/10.1038/s41420-026-03413-3</a></p>
<p><strong>Image Credits:</strong> AI Generated</p>
<p><strong>DOI:</strong> <a href="https://doi.org/10.1038/s41420-026-03413-3" rel="noopener noreferrer">10.1038/s41420-026-03413-3</a></p>
<p><strong>Keywords:</strong> Amyloid, peptides, alter, redox, status, oxygen, transport, function, blood, cells, scientific research</p>
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		<post-id xmlns="com-wordpress:feed-additions:1">303864</post-id>	</item>
		<item>
		<title>Cytokine-Driven microRNA Shifts in Brain Endothelial Cells Offer New Route to Protect the Blood-Brain Barrier</title>
		<link>https://scienmag.com/cytokine-driven-microrna-shifts-in-brain-endothelial-cells-offer-new-route-to-protect-the-blood-brain-barrier/</link>
		
		<dc:creator><![CDATA[Cassandra Pierce]]></dc:creator>
		<pubDate>Fri, 16 Oct 2026 16:22:03 +0000</pubDate>
				<category><![CDATA[Science News]]></category>
		<category><![CDATA[alter]]></category>
		<category><![CDATA[blood-brain barrier]]></category>
		<category><![CDATA[blood-brain barrier disruption]]></category>
		<category><![CDATA[blood-brain barrier protection strategies]]></category>
		<category><![CDATA[brain endothelial cell signaling]]></category>
		<category><![CDATA[brain endothelial cells]]></category>
		<category><![CDATA[cerebral malaria]]></category>
		<category><![CDATA[cytokine-driven neuroinflammatory disease pathways]]></category>
		<category><![CDATA[cytokine-induced microRNA regulation]]></category>
		<category><![CDATA[cytokines]]></category>
		<category><![CDATA[IFN-gamma]]></category>
		<category><![CDATA[microRNA landscape in neurovascular health]]></category>
		<category><![CDATA[microRNAs]]></category>
		<category><![CDATA[miR-155]]></category>
		<category><![CDATA[miRNA]]></category>
		<category><![CDATA[molecular mechanisms of blood-brain barrier breakdown]]></category>
		<category><![CDATA[molecular targets for cerebral malaria treatment]]></category>
		<category><![CDATA[neuroinflammation]]></category>
		<category><![CDATA[neuroinflammation and barrier integrity]]></category>
		<category><![CDATA[pro-inflammatory]]></category>
		<category><![CDATA[role of TNF-alpha and interferon gamma in blood-brain barrier]]></category>
		<category><![CDATA[therapeutic targeting of microRNAs in neuroinflammation]]></category>
		<category><![CDATA[tight junction modulation in brain endothelial cells]]></category>
		<category><![CDATA[TNF-alpha]]></category>
		<guid isPermaLink="false">https://scienmag.com/?p=286782</guid>

					<description><![CDATA[A new review shows how TNF-α and IFN-γ rewire microRNA profiles in brain endothelial cells, dismantling blood-brain barrier junctions and pointing toward miRNA-based therapies for cerebral malaria.]]></description>
										<content:encoded><![CDATA[<p>When infection or inflammation strikes the brain, the body&#8217;s most formidable defense—the blood-brain barrier—can become its own weak point. A new review published in Frontiers in Malaria synthesizes evidence that two pro-inflammatory cytokines, tumor necrosis factor-alpha (TNF-α) and interferon gamma (IFN-γ), rewire the microRNA landscape of human brain endothelial cells, driving molecular changes that loosen the tight junctions holding the barrier together. The work, led by Nahla Galal Metwally, Sara Mohamad, and Iris Bruchhaus of the Bernhard Nocht Institute for Tropical Medicine in Hamburg, argues that these tiny regulatory RNAs are not bystanders in barrier breakdown but active controllers of it—and that targeting them could open a new therapeutic front in cerebral malaria and other neuroinflammatory diseases.</p>
<p>The blood-brain barrier is built from brain microvascular endothelial cells joined by tight junctions and adherens junctions, protein assemblies that include claudins, occludin, and junctional adhesion molecules anchored to the cytoskeleton by zonula occludens (ZO) scaffolding proteins. This architecture restricts paracellular permeability and keeps the central nervous system insulated from the bloodstream. During infection, activated immune cells release TNF-α and IFN-γ, which act directly on brain endothelial cells. TNF-α increases paracellular permeability in a dose-dependent manner and enhances pathogen penetration, while IFN-γ induces morphological changes, surface expression of class II major histocompatibility complex antigens, and increased permeability to macromolecules. The result is a barrier that admits immune cells, pathogens, and solutes it would normally exclude.</p>
<p>The review details the intracellular signaling cascades through which these cytokines exert their effects. TNF-α binding to its receptors activates the IκB kinase complex, leading to degradation of IκB proteins and nuclear translocation of NF-κB, a transcription factor that switches on genes for adhesion molecules, chemokines, and cytokines. Recent studies show that this inflammatory reprogramming compromises barrier integrity, and that NF-κB inhibition can prevent the morphological remodeling, lipid accumulation, and junctional disruption that follow cytokine stimulation. Mitogen-activated protein kinase pathways—ERK, JNK, and p38—are also activated, contributing to tight junction disruption and matrix metalloproteinase production; TNF-α-induced MMP-9 expression in human cerebral microvascular endothelial cells proceeds through the Ca²⁺/CaMKII/ERK/NF-κB pathway. Glycogen synthase kinase-3β emerges as another key node: its inhibition restores barrier integrity and reduces adhesion molecule expression, partly by modulating miRNA expression and activating the Wnt/β-catenin pathway. Separately, tissue-nonspecific alkaline phosphatase activity, which supports barrier maintenance via the ROCK pathway, is significantly decreased by TNF-α and IFN-γ treatment, promoting cytoskeletal remodeling and barrier loss.</p>
<p>At the heart of the review is the argument that microRNAs—roughly 22-nucleotide non-coding RNAs that bind complementary sequences in the 3&#8242; untranslated regions of target mRNAs, causing translational repression or degradation—translate cytokine signaling into structural barrier failure. Comprehensive profiling shows that TNF-α stimulation of human brain microvascular endothelial cells downregulates 123 miRNAs and upregulates 193. Among the most consistently induced are members of the let-7 family and miR-98, which target the inflammatory chemokines CCL2 and CCL5, suggesting a built-in negative feedback loop to restrain excessive inflammation. In peripheral endothelial cells, TNF-α upregulates miR-31 and miR-17-3p, which target E-selectin and ICAM-1 respectively—findings not yet formally validated in brain endothelium but likely conserved across vascular beds. In brain endothelial cells themselves, miR-125a-5p is upregulated and dampens TNF-α-mediated ICAM-1 expression while reducing monocyte transmigration.</p>
<p>The most extensively characterized cytokine-responsive miRNA is miR-155, which is strongly and rapidly upregulated by combined TNF-α and IFN-γ treatment. Transcriptomic analysis reveals that miR-155 overexpression in human cerebral microvascular endothelial cells downregulates 390 transcripts, with enrichment in processes related to translation, focal adhesion, and inter-endothelial junctional complexes. Its validated targets include annexin-2, claudin-1, dedicator of cytokinesis 1, and syntenin-1. Overexpression of miR-155 mimics cytokine-induced junctional disorganization and permeability increases, while loss of miR-155 in knockout mice reduces barrier leakage in models of neuroinflammation. In contrast, miR-146a—also upregulated by the cytokines and elevated in microvessels of active multiple sclerosis lesions—appears protective, repressing RhoA, NFAT5, IRAK1, and TRAF6 to inhibit NF-κB activation and decrease adhesion molecule expression, thereby reducing T-cell adhesion to the endothelium.</p>
<p>The review emphasizes that timing matters. Early-phase responses within 6 to 12 hours feature rapid upregulation of miR-155 and miR-146a as immediate modulators of inflammatory signaling. Intermediate-phase responses between 12 and 48 hours sustain these miRNAs while additional regulators of junctional proteins emerge, with the balance between barrier-disrupting and barrier-protective species determining the extent of dysfunction. Beyond 48 hours, compensatory upregulation of barrier-protective miRNAs such as let-7 and miR-98 may attempt to restore homeostasis. Dose is equally decisive: lower concentrations of TNF-α and IFN-γ activate caspase-3 and caspase-9, increasing paracellular permeability and redistributing junctional complexes without killing the cells, while higher concentrations fully activate caspase-3/7, triggering endothelial apoptosis and complete barrier breakdown. Combined cytokine treatment also causes redistribution of ZO-1 and VE-cadherin from cell-cell contacts to the cytoplasm, disrupting both tight and adherens junctions.</p>
<p>The authors propose a three-level framework—cytokine-specific, context-specific, and disease-specific—to organize this complexity. Cytokine-specific effects are those directly demonstrated in brain endothelial cells, such as the NF-κB-driven miR-155 and miR-146a responses. Context-specific effects depend on cytokine concentration, exposure duration, and vascular bed: low-dose TNF-α primarily induces reversible tight-junction reorganization in which miR-155 leads, whereas high-dose or prolonged co-exposure shifts toward caspase-mediated breakdown with a partially distinct miRNA signature. Disease-specific effects layer pathogen- or tissue-derived signals on top of the cytokine background. Cerebral malaria adds sequestration-driven endothelial activation and parasite-derived extracellular vesicles; ischemic stroke superimposes hypoxia, inducing miR-210 and miR-212/132; multiple sclerosis combines chronic IFN-γ exposure with autoimmune T-cell signaling. The same miRNA can therefore appear barrier-protective in one disease and barrier-disrupting in another.</p>
<p>Cerebral malaria, caused by Plasmodium falciparum, serves as the review&#8217;s translational case study. Comparisons of infected red blood cells and TNF-α on human brain endothelial cells reveal that TNF-α induces strong endothelial activation with only modest permeability increase, whereas infected erythrocytes cause a marked permeability rise and preferentially trigger an endoplasmic reticulum stress response—evidence that parasite-specific signaling is a major driver of barrier disruption beyond cytokines alone. Infected erythrocyte-derived extracellular vesicles deliver miR-451a and other Ago2-miRNA complexes into endothelial cells, reducing caveolin-1 expression and altering barrier function, and are also enriched in let-7i, miR-150, and miR-146a—the same miRNAs that host cytokines induce endogenously. In experimental cerebral malaria in mice, circulating exosomal miR-155 rises over the disease course, miR-155 deficiency preserves barrier integrity, and antagomir-155 reduces vascular leak in microvessels exposed to sera from Ugandan children with cerebral malaria. Yet in human cohorts, circulating miR-155 has not consistently distinguished cerebral malaria from uncomplicated disease, and miR-451a&#8217;s abundance in erythrocytes generally complicates its specificity as a biomarker—discrepancies the authors attribute to differences between murine CD8⁺ T-cell-driven pathology and human sequestration-dominated disease, cohort age and genotype variation, and the compartment in which miRNAs are measured.</p>
<p>The therapeutic implications are substantial. The review outlines three strategies: inhibiting barrier-disrupting miRNAs such as miR-155 with antisense oligonucleotides or locked nucleic acid inhibitors; delivering barrier-protective miRNAs such as miR-98, let-7, or miR-146a using synthetic mimics or exosome-based systems, building on proof of concept from bone marrow stromal cell-derived exosomal miR-21a-5p, which upregulates claudin-5, occludin, and ZO-1 in stroke models; and modulating upstream signaling pathways such as NF-κB or GSK3β to shift the miRNA balance toward protection. Major challenges remain, including delivering miRNA therapeutics across the very barrier they aim to protect, minimizing off-target effects from miRNAs that can regulate hundreds of genes, and determining optimal timing—early intervention before severe barrier breakdown is likely most effective. The authors call for single-cell sequencing to map miRNA heterogeneity across endothelial populations, mechanistic validation of additional targets, investigation of interactions with long non-coding and circular RNAs, and comparative studies of species differences. If those hurdles can be cleared, the microRNA networks that cytokines exploit to dismantle the blood-brain barrier may become the very levers clinicians pull to keep it intact.</p>
<p><strong>Subject of Research:</strong> Cytokine-induced microRNA changes in brain endothelial cells and their role in blood-brain barrier dysfunction</p>
<p><strong>Article Title:</strong> How do pro-inflammatory cytokines alter miRNA profiles in brain endothelial cells? Mechanisms, consequences, and therapeutic strategies for blood-brain barrier protection</p>
<p><strong>Article References:</strong> Metwally, N. G., Mohamad, S., &amp; Bruchhaus, I. (2026). How do pro-inflammatory cytokines alter miRNA profiles in brain endothelial cells? Mechanisms, consequences, and therapeutic strategies for blood-brain barrier protection. <em>Frontiers in Malaria, 4</em>, Article 1849845. <a href="https://doi.org/10.3389/fmala.2026.1849845" rel="noopener noreferrer">https://doi.org/10.3389/fmala.2026.1849845</a></p>
<p><strong>Image Credits:</strong> AI Generated</p>
<p><strong>DOI:</strong> <a href="https://doi.org/10.3389/fmala.2026.1849845" rel="noopener noreferrer">10.3389/fmala.2026.1849845</a></p>
<p><strong>Keywords:</strong> blood-brain barrier, microRNAs, TNF-alpha, IFN-gamma, cerebral malaria, neuroinflammation, brain endothelial cells, miR-155, pro-inflammatory, cytokines, alter, miRNA</p>
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		<post-id xmlns="com-wordpress:feed-additions:1">286782</post-id>	</item>
		<item>
		<title>Culture media alter retinal organoid physiology promoting AAV transduction and retinal ganglion cell survival</title>
		<link>https://scienmag.com/culture-media-alter-retinal-organoid-physiology-promoting-aav-transduction-and-retinal-ganglion-cell-survival/</link>
		
		<dc:creator><![CDATA[Gregory Coleman]]></dc:creator>
		<pubDate>Sat, 12 Sep 2026 04:06:43 +0000</pubDate>
				<category><![CDATA[Medicine]]></category>
		<category><![CDATA[AAV gene transduction efficiency]]></category>
		<category><![CDATA[alter]]></category>
		<category><![CDATA[cell]]></category>
		<category><![CDATA[Culture]]></category>
		<category><![CDATA[culture media influence]]></category>
		<category><![CDATA[ganglion]]></category>
		<category><![CDATA[impact of media composition on retinal physiology]]></category>
		<category><![CDATA[media]]></category>
		<category><![CDATA[neural differentiation factors]]></category>
		<category><![CDATA[organoid]]></category>
		<category><![CDATA[organoid culture optimization]]></category>
		<category><![CDATA[physiology]]></category>
		<category><![CDATA[pluripotent stem cell differentiation]]></category>
		<category><![CDATA[promoting]]></category>
		<category><![CDATA[retinal]]></category>
		<category><![CDATA[retinal cell layer formation]]></category>
		<category><![CDATA[retinal developmental stages]]></category>
		<category><![CDATA[retinal embryogenesis in vitro]]></category>
		<category><![CDATA[retinal ganglion cell survival]]></category>
		<category><![CDATA[Retinal organoid development]]></category>
		<category><![CDATA[retinal tissue engineering]]></category>
		<category><![CDATA[Scientific Research]]></category>
		<category><![CDATA[survival]]></category>
		<category><![CDATA[transduction]]></category>
		<guid isPermaLink="false">https://scienmag.com/?p=193586</guid>

					<description><![CDATA[The observation that culture media composition can reshape the physiology of retinal organoids carries implications that extend well beyond the immediate experimental findings. Retinal organoids are three-dimensional structures derived from pluripotent stem cells that recapitulate, to a remarkable degree, the]]></description>
										<content:encoded><![CDATA[<p>The observation that culture media composition can reshape the physiology of retinal organoids carries implications that extend well beyond the immediate experimental findings. Retinal organoids are three-dimensional structures derived from pluripotent stem cells that recapitulate, to a remarkable degree, the developmental choreography of the human retina. Over weeks and months in culture, these self-organizing tissues progress through stages that mirror embryonic retinogenesis: early optic vesicle-like structures emerge, retinal progenitor cells proliferate in a ventricular-like zone, and successive waves of differentiation generate the major retinal cell classes in the same order observed in vivo, with retinal ganglion cells appearing first, followed by horizontal cells, amacrine cells, and cone photoreceptors, and finally rod photoreceptors and Müller glia. Because this sequence depends on intrinsic developmental programs as well as extrinsic environmental cues, the composition of the culture medium is not a passive backdrop but an active participant in determining which programs proceed, at what pace, and with what fidelity.</p>
<p>Standard organoid culture media typically include a basal formulation such as DMEM/F12 supplemented with factors that promote neural differentiation, including N2 and B27 supplements, and often retinoic acid at later stages to encourage photoreceptor maturation. Variations among laboratories in the choice of basal medium, the concentration of supplements, the presence or absence of serum components, and the timing of factor additions have long been recognized as sources of heterogeneity, but the systematic consequences of these choices for downstream applications have been less thoroughly characterized. The finding that media alter both adeno-associated virus transduction and retinal ganglion cell survival suggests that seemingly minor formulation differences can propagate into functional outcomes that matter enormously for translational work.</p>
<p>Adeno-associated virus vectors are the leading platform for retinal gene therapy, with approved products demonstrating that subretinal or intravitreal delivery can produce durable clinical benefit in inherited retinal degenerations. The success of AAV-mediated gene transfer depends on a cascade of events: vector particles must reach the target cells, bind to cell surface receptors, undergo endocytosis, traffic through the cytoplasm, enter the nucleus, uncoat, and convert their single-stranded genome into a transcriptionally competent double-stranded form. Each step can be influenced by the physiological state of the target cell, including membrane composition, endosomal trafficking dynamics, proteasome activity, and the expression of factors that second-strand synthesis. If culture media shift cells into states that favor or hinder any of these steps, then organoid-based assessments of vector tropism and potency will yield results that are artifacts of the culture condition rather than faithful predictions of clinical behavior.</p>
<p>This consideration is particularly acute because organoids are increasingly used as preclinical screening platforms for vector engineering. Researchers seeking capsids with improved photoreceptor tropism, or with the ability to penetrate the inner limiting membrane after intravitreal injection, frequently validate their designs in retinal organoids before advancing to animal studies. A capsid that appears highly efficient in organoids maintained in one medium might underperform in organoids maintained in another, not because the capsid has changed but because the cellular context has. Standardizing media composition, or at minimum reporting it comprehensively and testing key findings across multiple formulations, would strengthen the predictive value of such screens and reduce the risk of pursuing vector designs whose apparent advantages do not survive a change of culture conditions.</p>
<p>The effects on retinal ganglion cell survival are equally consequential. Retinal ganglion cells are the projection neurons of the visual system, conveying visual information from the retina to the brain through the optic nerve, and their degeneration underlies glaucoma and other optic neuropathies. In organoid culture, ganglion cells are notoriously fragile; they are among the first cell types generated, they reside in the innermost layer of the tissue, and they depend on trophic support that is difficult to reproduce in a dish. Their progressive loss during long-term organoid culture is a well-documented limitation, and it complicates any effort to model ganglion cell diseases or to test neuroprotective strategies. If specific medium components can substantially extend ganglion cell survival, this opens two important avenues: first, the creation of longer-lived organoid models in which disease-relevant cell types remain available for study; and second, the identification of the trophic factors and metabolic conditions that ganglion cells require, which may themselves point toward therapeutic targets.</p>
<p>The mechanistic links between medium composition and cell survival likely involve several intersecting pathways. Oxidative stress is a prominent candidate, since retinal neurons are metabolically demanding and vulnerable to reactive oxygen species, and the antioxidant capacity of medium supplements such as those in B27 varies with formulation and with the degradation of components over time in culture. Energy metabolism is another: the retina is among the most oxygen-consuming tissues in the body, and photoreceptors in particular rely on aerobic glycolysis, a metabolic mode whose support depends on glucose and pyruvate availability in the medium. Growth factor signaling, including pathways involving BDNF, CNTF, GDNF, and insulin-like growth factors, also modulates ganglion cell survival, and the presence, stability, and concentration of such factors differ across media formulations. Even the buffering system and the resulting pH stability can influence neuronal health, as can osmolarity and the accumulation of metabolic waste products between medium changes.</p>
<p>For AAV transduction specifically, medium composition might act through effects on the cell surface. The glycocalyx, the dense layer of sugars coating the plasma membrane, provides attachment points that many AAV seruses exploit, and its composition is sensitive to culture conditions, including the availability of specific sugars and the activity of glycosyltransferases. Heparan sulfate proteoglycans serve as primary attachment receptors for several AAV serotypes, and sialic acid residues are critical for others. Media that alter glycosaminoglycan synthesis or sialylation could therefore change the efficiency of the initial binding step. Downstream, intracellular trafficking depends on the cytoskeleton and on endosomal pH, both of which can be modulated by medium components such as ammonium chloride accumulation, chloroquine-like compounds, or simply the energetic state of the cell. These mechanisms offer plausible, testable explanations for how the same vector applied to the same organoid type can perform differently across media.</p>
<p>The broader lesson resonates with a recurring theme in stem cell biology: the environment is part of the experiment. Organoids are often described as miniaturized versions of human tissues, but they are better understood as products of a continuous dialogue between intrinsic developmental programs and the culture environment. Small differences in oxygen tension, media exchange schedules, matrix composition, and the physical handling of cultures have all been shown to affect organoid morphology and cell type composition. The present findings add media formulation to this list in a way that directly touches two of the most translationally important readouts: gene delivery efficiency and survival of a clinically critical neuron.</p>
<p>From a practical standpoint, laboratories working with retinal organoids for gene therapy applications should consider several measures. Detailed documentation of medium composition, including lot numbers of supplements whose activity varies between batches, would improve reproducibility across the field. Cross-validation of key results in at least two distinct media formulations would reveal whether findings are robust or condition-dependent. Where possible, matching the metabolic and trophic environment of the organoid to the physiological state of the target tissue in vivo would improve the clinical relevance of preclinical testing. For ganglion cell studies specifically, optimizing media for survival may need to be balanced against the goal of photoreceptor maturation, since conditions that favor one cell class may not favor another, and the developmental timing of these requirements may differ.</p>
<p>There are also implications for disease modeling. Many inherited retinal diseases are cell-type specific, and the value of an organoid model depends on maintaining the relevant cells in a state that resembles their in vivo counterpart. Ganglion cell loss in culture has limited the use of organoids for modeling optic neuropathies such as those caused by mutations in OPA1 or other genes affecting mitochondrial function. If optimized media extend ganglion cell survival substantially, models of these diseases become feasible, enabling the study of pathogenesis in a human developmental context and the screening of candidate neuroprotective compounds. Similarly, for glaucoma research, where the interplay between elevated intraocular pressure, axonal transport disruption, and somal survival is difficult to disentangle in animal models, longer-lived organoid systems with robust ganglion cell populations would provide a complementary human platform.</p>
<p>The intersection with AAV biology deserves particular attention as the gene therapy field matures. Dose-limiting toxicity, immune responses, and the challenge of achieving pan-retinal transduction after intravitreal delivery remain central obstacles. Organoids offer a human-relevant system in which to evaluate candidate capsids, promoters, and expression cassettes, but their utility depends on the transduction results reflecting what would occur in a patient retina. The finding that media promote or suppress transduction suggests that part of the variability reported across organoid studies of AAV tropism may be attributable to culture conditions rather than to genuine differences in vector performance. Disentangling these variables will require systematic comparisons in which identical vectors are applied to organoids raised in parallel under different media conditions, with careful quantification of both transduction efficiency and the cell-type composition of the tissues.</p>
<p>It is also worth considering how these findings fit into the larger regulatory and manufacturing landscape. As retinal organoids move toward use in potency assays and release testing for cell and gene therapy products, the dependence of their properties on media composition becomes a matter of product consistency. Regulatory frameworks emphasize the characterization of critical quality attributes, and for organoid-based assays, the culture medium is arguably a critical reagent whose composition must be controlled with the same rigor as the biological material itself. Manufacturers of media and supplements may need to provide more detailed specifications, and users may need to implement qualification procedures for each new lot, particularly for supplements such as B27 whose complex composition includes components with variable biological activity.</p>
<p>Looking forward, the systematic mapping of how individual medium components affect retinal organoid physiology could yield a design framework for culture conditions tailored to specific applications: media optimized for photoreceptor maturation for studies of inherited photoreceptor degenerations, media optimized for ganglion cell survival for optic neuropathy models, and media that support efficient AAV transduction for vector validation studies. Such an approach would treat the medium as an engineering variable rather than a fixed convention, transforming a source of uncontrolled variability into a tool for shaping organoid properties. The present work, by demonstrating that culture media alter both AAV transduction and retinal ganglion cell survival in retinal organoids, provides both a caution about the interpretation of existing organoid studies and a constructive starting point for this more deliberate approach to organoid culture design.</p>
<p><strong>Subject of Research:</strong> Culture media alter retinal organoid physiology promoting AAV transduction and retinal ganglion cell survival</p>
<p><strong>Article Title:</strong> Culture media alter retinal organoid physiology promoting AAV transduction and retinal ganglion cell survival</p>
<p><strong>Article References:</strong> O’Hara-Wright, M., Lim, B. Y., M. Mangala, M., Kaiser, V., Wong, E., Aubin, D., Nemeruck, V., Reynisson, H., Doroudian, F., Chan, O. P. Y., Aryamanesh, N., A. Paulo, J., Palomba, S., Mirzaei, M., Ginn, S. L., &amp; Gonzalez-Cordero, A. (2026). Culture media alter retinal organoid physiology promoting AAV transduction and retinal ganglion cell survival. <em>Gene Therapy</em>. <a href="https://doi.org/10.1038/s41434-026-00642-0" rel="noopener noreferrer">https://doi.org/10.1038/s41434-026-00642-0</a></p>
<p><strong>Image Credits:</strong> AI Generated</p>
<p><strong>DOI:</strong> <a href="https://doi.org/10.1038/s41434-026-00642-0" rel="noopener noreferrer">10.1038/s41434-026-00642-0</a></p>
<p><strong>Keywords:</strong> Culture, media, alter, retinal, organoid, physiology, promoting, transduction, ganglion, cell, survival, scientific research</p>
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