Five-Year Brain Organoids Reveal New Insights Into Human Development

The human brain undergoes development over a two-decade period, making it difficult for researchers to study this process. Traditionally, donated human brain tissue and animal models have been used, but these have limitations as they provide snapshots of brain development and differ from the human brain in composition and timing.

Brain organoids, however, have shown promise in extending the lifespan of tissue to over five years while maintaining accurate development. A recent study published in Nature details how researchers extended brain organoid lifespan, allowing them to closely observe human brain development. By adapting the culture medium to support spontaneous neuronal activity, the team was able to maintain organoids for extended periods.

This breakthrough enables researchers to investigate neurodevelopment, model brain disorders, and test potential drugs. The organoids exhibit development in the same order as human brain development, form complex neuronal connections, and show gene expression patterns characteristic of human development. Epigenetic changes also accumulate in a pattern consistent with human development.

After about a year, the organoids display features typically observed after birth. The cells retain a "memory" of developmental time, producing late-stage cell types even when combined with younger cells. The researchers are now exploring ways to enhance these models, such as improving vascularization and cortical layering, to create more accurate representations of the human brain.