Silicon nanowires restore function in aged human T cells

Researchers at the Georgia Institute of Technology have demonstrated that silicon nanowires can deliver microRNA into aged human T cells with high efficiency, restoring key immune functions that decline with age. The study, published in Cell Biomaterials, was led by biomedical engineer Ankur Singh and doctoral student Zhonghao Dai.

T cells are the immune system's primary defenders against viruses, abnormal cells, and early-stage cancers. As people age, the body produces fewer new T cells, and existing ones become exhausted, losing their ability to proliferate and kill target cells effectively. The team sought to determine whether these aged cells could regain lost function rather than simply accepting immune decline as inevitable.

Existing methods for delivering genetic material into T cells often damage the fragile cells or fail to reach a sufficient proportion of them. The researchers used microscopic silicon nanowires to introduce microRNA — small RNA molecules that regulate gene expression — into more than 90% of aged T cells without causing harm. The microRNA acted as instructions to reset the cells' internal programs.

Modifying just four or five genes was sufficient to bring the aged T cells closer to a youthful functional state. The treated cells became more active, multiplied more readily, and regained the ability to attack infected and cancerous cells. The improvements were observed in T cells from healthy older adults, cancer survivors, and patients currently living with cancer, suggesting broad applicability across different health conditions.

Singh noted that the approach could have wide applications, including cancer, infectious diseases, inflammatory bowel disease, and autoimmunity, and could improve vaccine responses in older adults. Currently, the restored function lasts about two weeks. The team is working to extend the duration of the effect, though the underlying cellular aging process continues.

The research represents a proof-of-concept for reprogramming aged immune cells without reversing aging itself. By temporarily restoring T cell function, the technique offers a potential strategy to enhance immune resilience in older populations facing new infections, cancer, or other immune challenges.