Natural Killer (NK) cells are gaining attention in the realm of research focused on neurodegenerative diseases such as Alzheimer’s, Parkinson’s, amyotrophic lateral sclerosis (ALS), and multiple sclerosis. As part of the innate immune system, NK cells are instrumental in identifying and responding to infected, stressed, or irregular cells, and they play a role in modulating inflammatory responses through interactions with other immune cells. Although research is advancing, scientists caution that the evidence for NK cell therapy as a treatment for these conditions is still in its infancy.
A Phase I clinical study conducted in 2025 explored the use of expanded NK cells in patients with Alzheimer’s disease. This study involved 11 participants, with 10 completing the evaluable analysis. These individuals received intravenous infusions of an autologous, non-genetically modified expanded NK cell product every three weeks. The primary aim was to assess safety, with additional monitoring of cognitive measures and cerebrospinal fluid biomarkers linked to neuroinflammation, neurodegeneration, amyloid, and tau. Researchers observed no adverse events directly attributable to the NK cell product and noted preliminary changes in some cognitive measures and biomarkers, including pTau181 and GFAP. However, the study’s small size means it was not designed to evaluate the therapy’s ability to prevent or slow the progression of Alzheimer’s disease.
In the arena of Parkinson’s disease, preclinical studies have also highlighted the potential role of NK cells. A 2020 study published in the Proceedings of the National Academy of Sciences demonstrated that NK cells could interact with and degrade alpha-synuclein aggregates in laboratory and animal models. When NK cells were depleted in a mouse model, increased alpha-synuclein pathology and neuroinflammation were observed, indicating a potential role for NK cells in regulating immune activity linked to Parkinson’s. Despite these findings, the evidence remains primarily preclinical and does not establish NK cell therapy as an effective treatment for Parkinson’s disease in humans.
Research continues to underscore the complexity of NK cells’ roles in neurological diseases. Different populations of NK cells may perform various functions, and their effects can vary based on disease type, stage, and the surrounding tissue environment, making it clear that merely increasing NK cell numbers may not yield beneficial outcomes. Researchers are now focused on identifying which NK cell populations, activation states, doses, and treatment schedules could be most effective. Key questions also remain about how well infused cells can influence the central nervous system, their duration of activity, which patients may benefit, and whether treatment can alter the long-term progression of neurodegenerative diseases.
Current evidence suggests that while NK cells are active in immune surveillance and regulation, their potential interaction with neuroinflammation and abnormal protein aggregates is still emerging. NK cell therapy remains an investigational area of cellular medicine, requiring more extensive clinical studies to determine effectiveness and long-term safety. Individuals considering cellular therapies are advised to consult with qualified healthcare professionals to evaluate scientific evidence, safety information, and regulatory status. It is important to note that NK cell therapy for neurodegenerative diseases is still investigational and not an established treatment for Alzheimer’s or Parkinson’s disease.
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