Compared to the issues that come with, say, a failing liver, skin aging can look like more of a vanity problem. But aging in both tissues, and multiple others, is driven by the same underlying molecular mechanisms. One of those mechanisms is fibrosis, the cross-linking of extracellular matrix (ECM) proteins that leads to tissue stiffening. Anti-aging company Cambrian Biopharma Inc. has argued that stiffening of the ECM should be considered one of the formal hallmarks of aging.