fibrosis

Fibrosis is scarring gone too far: a build-up of excess fibrous tissue, mostly the protein collagen, that stiffens an organ and crowds out the working cells that actually do its job. A little scar seals a wound, but fibrosis is like a contractor who keeps pouring concrete long after the hole is filled, until the room is solid and useless. It is, in effect, the enemy of true regeneration.

It usually starts as ordinary repair that never switches off. When an organ is injured again and again, the repair cells keep laying down tough collagen scaffolding, replacing soft, specialized tissue with stiff scar. Over time the organ hardens and shrinks in capability, because scar cannot pump, filter, or breathe the way the original tissue did.

Fibrosis underlies many serious chronic diseases — scarred livers (cirrhosis), stiff lungs, and a heart that scars after a heart attack instead of regrowing. Because scar tissue blocks rebuilding, a major aim of regenerative medicine is to prevent or reverse fibrosis so that real, functional tissue has room to return.