Restoration versus reconstruction: cellular mechanisms of skin, nerve and muscle regeneration compared

Table 3 Kinetics of wound healing of the muscle: main phases and players

	Destruction	Repair	Remodeling
	Days following injury
When	1 to 5	3 to 7	8 to weeks
Where	hematoma (between fiber stumps)	necrotic segment	newborn fibers regenerated segment
What	phagocytosis of necrotized tissue inflammation Satellite cell activation	myofiber formation (fusion of muscle precursor cells)	myofiber growth
What		gap refilling (myotube fusion with each other and surviving fibers)	myofiber function (fiber type specif.) scar reorganization
Who	muscle fibers ⁽¹⁾ ⁽²⁾	muscle fibers ^{(4) (5)}	fiber cytoskeleton ⁽⁷⁾
	muscle fibers ⁽³⁾		nerve sprouts ⁽⁸⁾
	connective tissue ⁽⁴⁾		intervening scar ⁽⁹⁾
	macrophages ⁽⁴⁾
	neutrophils ⁽⁵⁾
How	HGF ⁽¹⁾	IGF-1 and−2 ⁽⁴⁾	myofibril remodeling ⁽⁷⁾
	FGF-1-2-4 and-6 ⁽²⁾	IL-4 ⁽⁵⁾	nerve activity (frequency)⁽⁸⁾
	MSTN/GDF8 ^{(3) (4)}		scar retraction ⁽⁹⁾
	LIF ^{(3) (4)}		scar retraction ⁽⁹⁾
	TNF ⁽⁵⁾

Following injury, regeneration of the muscle can be schematically divided in three main phases. Complete muscle regeneration in humans may take several weeks. In addition to the timeline (When), each row indicates the tissue involved (Where), the main output (What), the cell type involved most (Who) and some of the main molecular mediators (How) responsible for the various phases of wound healing. Matching superscripts highlight the cells that produce the corresponding growth factors or the cellular structures responsible for a given function. Fibroblast growth factor (FGF); hepatocyte growth factor (HGF); insulin-like growth factor (IGF); interleukin-4 (IL-4); leukemia inhibitory factor (LIF); myostatin (MSTN), also known as growth differentiation factor 8 (GDF-8); tumor necrosis factor (TNF).

ISSN: 2050-490X