Immunomodulation in regeneration
The immune system is not an obstacle to healing — its early behaviour largely determines whether tissue scars or rebuilds.
Inflammation was once treated as something to suppress so that healing could proceed. The current view is closer to the opposite: the early immune response is an instructive phase, and its character predicts the outcome.
Macrophages are the usual focus. Broadly, an early pro-inflammatory phase clears debris and recruits cells, and a later reparative phase supports matrix deposition and vessel growth. A response stuck in the first phase tends toward chronic inflammation and scar; one that transitions appropriately tends toward regeneration. Biomaterials themselves shape this — surface chemistry and degradation products of a scaffold influence how macrophages behave, an effect sometimes called osteoimmunomodulation in bone.
This is also part of why Mesenchymal stem cells are studied: much of their benefit appears to come not from becoming new tissue but from the immunomodulatory signals they release — see Exosomes and the secretome.
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