TABLE 1.

Key differences between adult and fetal wound healing

	Fetal wounds	Adult wounds
Inflammation (Longaker et al., 1994; Lorenz et al., 1992)	Few or no inflammatory cells	Many inflammatory cells
Hyaluronic acid (Nwomeh et al., 1998; Shah et al., 1995)	High, prolonged levels, promotes cellular movement	Lower levels, inhibits cellular movement
Collagen (Gurtner et al., 2008; McPherson et al., 1988)	Elevated ratio of type III compared to that of type I	Elevated ratio of type I compared to that of type III
Keratin (Lorenz et al., 1992; Rowlatt, 1979)	K8 and K19 are present during fetal development	Absence of K8 and K19
Mast cells (Gurtner et al., 2008; Walmsley et al., 2015)	Low numbers and less mature	High numbers, more mature
TGF-β (Burrington, 1971; Rowlatt, 1979; Sen et al., 2009)	Low expression of TGF-β1 and TGF-β2	High expression of TGF-β1 and TGF-β2
Stem cells (Sen et al., 2009)	Higher levels of MSCs at injury sites with accompanying E-cadherin-positive cells	Lower levels of MSCs at injury sites without accompanying E-cadherin-positive cells

MSCs = mesenchymal stem cells (Reprinted with permission from Walmsley et al., 2015. Copyright 2015 LWW).