Johns Hopkins mini brains reveal patient-specific Alzheimer’s drug
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- Johns Hopkins Medicine researchers created hindbrain organoids from induced pluripotent stem cells reprogrammed from blood samples of Alzheimer's patients at the NIH-funded Johns Hopkins Alzheimer's Disease Research Center, producing hundreds of pea-sized tissue clusters containing serotonin-producing neurons.
- When treated with escitalopram oxalate, an SSRI commonly prescribed for Alzheimer's-related neuropsychiatric symptoms, some patient-derived organoids showed increased serotonin signaling and synaptic proteins while others displayed little or no molecular response — variation the researchers say could help identify patient subgroups most likely to benefit from specific drugs.
- Compared with healthy control organoids, Alzheimer's patient-derived organoids showed distinct molecular differences in proteins involved in brain cell communication, inflammation and disease-associated pathways, reproducing key biological features of the disease at the molecular level.
- The organoids released extracellular vesicles with lower levels of RAB3A, NSF and ATCAY — proteins critical for normal neuron signaling — and escitalopram treatment raised levels of some serotonin- and synapse-related proteins in certain samples, suggesting the vesicles could eventually serve as biomarkers for diagnosis, staging and treatment response.
- Study leader Vasiliki Machairaki, a Johns Hopkins associate professor of genetic medicine, described the work as one of the largest brain organoid studies in Alzheimer's research and outlined next steps including adding immune cells and vascular-like networks to make the tissues more lifelike.
- The study was published in Alzheimer's & Dementia and funded by the NIH, the Paul G. Allen Frontiers Foundation and the Richman Family Precision Medicine Center of Excellence in Alzheimer's Disease; Machairaki said a vesicle-based "liquid biopsy" remains an early-stage goal.
- Alzheimer's affects more than 7 million Americans, and nearly all patients experience neuropsychiatric symptoms such as anxiety, depression and agitation that SSRIs are prescribed to manage — though responses vary widely and no cure currently exists.
Why it matters: Alzheimer's affects more than 7 million Americans, and SSRIs — the drugs commonly prescribed for the anxiety, depression and agitation that nearly all patients develop — produce inconsistent responses that today clinicians cannot predict. The Johns Hopkins team's demonstration that hundreds of patient-derived brain organoids reproduce that variability at the molecular level gives drug developers a pre-clinical platform to test which Alzheimer's subgroups will respond to which psychiatric medications before human trials, while the extracellular vesicle findings open a path to a blood-based test for diagnosing and staging the disease.
