Humans have been fascinated about aging for centuries. However regardless of how curious we have been, studying aging has proven to be difficult, especially when studying its effects on neurons. Historically scientists have used cells from fast-aging animals as models, such as worms and mice. Although these models were significant there is still a large genetic gap between these organisms and humans, which ultimately led to the failure of all possible life-extending treatments based on these models. To circumvent this scientists have began using induced pluripotent stem cells (iPSC) from a patient’s skin cells and coaxing them into becoming neurons. However the problem here is that the conversion process also turns back the biological clock, making the iPSC-derived neurons appear as younger cells regardless of their original age.
The New Approach
Instead of taking the previous route of aged cells, to iPSCs, to neurons, scientists from Salk Institute used a method previously discovered in Stanford University, where they coax skin cells into fully functional neurons, skipping the induced embryonic stage. They found that the directly-converted neurons showed gene expression profiles implicated in aging, such as the decompartmentalization of proteins. Although only tried on neurons, scientists are hopeful it can also work on other tissues and that it could be expanded to highly-structured 3D cultures such as organoids.