The field of genomics is rapidly advancing, and with it, our understanding of the aging process is being revolutionized. Researchers at Rockefeller University have developed innovative techniques that provide unprecedented insights into the cellular dynamics of the aging brain. These methods, IRISeq and EnrichSci, are transforming our ability to study aging and disease, offering a more comprehensive view of the molecular changes that occur in our bodies as we age.
One of the most exciting aspects of these new approaches is their ability to map tissues without the need for traditional imaging methods. IRISeq, for instance, uses DNA as a molecular barcode to capture local gene expression information across tissues. This technique allows researchers to rebuild the layout of tissues at different levels of detail, providing a more cost-effective and efficient way to study large pieces of tissue or many tissue sections. By preserving spatial relationships between cells, IRISeq enables the study of how tissues function, change, and respond to disease across larger sample sets and broader contexts.
The team applied IRISeq to study inflammatory cellular neighborhoods in the aging brain, finding that inflammatory subtypes of microglia, oligodendrocytes, and astrocytes tend to cluster together in white matter and interact with one another. These findings suggest that white matter may be a particularly vulnerable region of the aging brain where disease-associated cellular states emerge and reinforce each other. For example, they found that immune cells called lymphocytes play a major role in driving inflammation in the aging brain in a very specific way, with their activity concentrated in certain regions, especially near the brain’s fluid-filled spaces known as ventricles.
The second technique, EnrichSci, is a single-nucleus RNA sequencing method that targets and isolates rare but biologically relevant cells in a mixed population of cells. By enriching for the rare target cells, EnrichSci then zooms in on each cell’s molecular programming. The researchers applied EnrichSci in the aging mouse brain to enrich for rare cell populations they’d previously identified as especially prone to problematic shifts during aging, among them subtypes of oligodendrocytes, which are found exclusively in the central nervous system. These cells ensheath neuronal axons in the brain and spinal cord and are linked to neurodegenerative diseases.
In these aging subtypes, the researchers uncovered changes in both gene expression and in influential genetic elements called exons, which are key to the post-transcriptional regulation of genes. The exonic changes they identified revealed that post-transcriptional regulation plays an important role in how oligodendrocytes age and could offer new targets for modulating these changes in age-related neurodegeneration. Surprisingly, the researchers also found that many genes don’t undergo significant changes in expression during the aging process, but their exons do, related to alternate splicing, a key mechanism for creating different protein functions. But such changes can also be linked to many diseases, including cancer.
These new techniques have the potential to function as both clinical and research tools for diagnosing disease and uncovering new biology across a wide range of conditions. The researchers hope to expand EnrichSci to jointly profile both RNA and chromatin accessibility, capturing gene and exon expression changes as well as their underlying epigenetic changes. By preserving spatial relationships between cells, IRISeq enables the study of how tissues function, change, and respond to disease across larger sample sets and broader contexts.
In conclusion, the advancements in genomics are providing us with a more nuanced understanding of the aging process and its underlying cellular dynamics. These new techniques, IRISeq and EnrichSci, are transforming our ability to study aging and disease, offering a more comprehensive view of the molecular changes that occur in our bodies as we age. As we continue to develop these methods, we can expect to uncover even more insights into the complex processes of aging and disease, potentially leading to new interventions and treatments.
