Repair versus regeneration
Why most human healing produces scar tissue, and what distinguishes it from true regeneration.
Healing and regeneration are not the same thing. Repair closes a wound quickly with fibrous scar tissue — mechanically adequate, biologically different from what it replaced, and usually unable to perform the original function. Regeneration restores the original architecture and function. Evolution generally favours speed, which is why repair dominates in adult humans.
Bone is the notable exception: it can heal without scar, which is why bone remodeling is a reference point for the whole field. Most other tissues, including mature dental tissue, regenerate poorly or not at all — which is precisely what makes them interesting research problems.
The practical question is what tips the balance. The immune response appears to be one lever: the character of early inflammation predicts whether tissue scars or rebuilds. Composition of the extracellular matrix is another. Much of regenerative medicine is an attempt to nudge repair back toward regeneration.
Related articles
- FoundationsWhat is regenerative medicine?An introduction to the field that aims to restore the structure and function of damaged tissue rather than merely replace it.
- BoneBone remodelingThe continuous cycle of resorption and formation that rebuilds the skeleton throughout life.
- FoundationsImmunomodulation in regenerationThe immune system is not an obstacle to healing — its early behaviour largely determines whether tissue scars or rebuilds.
- FoundationsThe extracellular matrixThe structural and signaling scaffold cells build around themselves — and the template engineered scaffolds try to imitate.
- FoundationsThe principles of tissue engineeringCells, scaffolds, and signals — the three-part framework underlying most attempts to build living tissue.
- FoundationsVascularization: the diffusion limitWhy engineered tissue thicker than a couple of hundred microns fails without a blood supply — the field's most stubborn bottleneck.