What is the “lifecycle” of an average eschar and what types of cells are involved in each stage?

Question

(after some deliberation in the comments, I've decided to make the question more general)

An eschar or "dry scab" often forms at a site of injury over a large cut or sore.

It seems as though the healing scab portion binds more strongly to the other scab cells than to those of the surrounding healthy tissue initially, as evidenced by the ability to remove the scab en masse without disturbing the edges of the actual wound (in surgical debridement or when the area is "picked" at). Then, the eschar bonds then bonds more strongly with the edges of the wounds (so it's more difficult to remove), and then finally, the underlying newly formed skin seems to push it off completely.

Does this accurately describe the "lifecycle" of a common dry scab, or are there other well defined stages in the process? What types of cells (platelets in the beginning? epithelials at the end?) are involved with each stage of the process?

Answer 1

Response to cutaneous tissue damage occurs is several distinct but overlapping phases. First an scab is formed as the blood is 'allowed' to clot. A matrix is formed as the platelets adhere to one another, which contracts and 'dries' (forces out the serum) to form a scab. This process clearly happens prior to tissue regeneration/formation to reduce further blood loss.

Fibrinogen

In response to damage to blood vessels a signaling cascade is initated that results in the massive production of fibrin, which is deposited at the site of wounding and subsequently forms blood clots by activating platelets and stabilising the matrix by cross-linking (see PDB's protein of the month 2006).

So this is why clots do not appear to be attached to the surrounding tissue; the fibrin causes the blood to form a matrix that is very tightly bound to itself. Only after clot formation does the tissue remodeling occur, and it is during this stage that the scab will 'bind' more stongly to the surrounding tissue.

The Cell Types and Processes of Wound Healing

This figure (from (Li, 2007)) shows the various stages that occur and cells that are involved in acute wound healing (wounds such as burns and cuts that heal "in a timely fashion");