Table 1.
Amniotic membrane and umbilical cord action by cell type
| Cell type | Action | Clinical implication | Supporting publication |
|---|---|---|---|
| Neutrophil | Promotes apoptosis of fMLP- or LPS-activated neutrophils | Reduces inflammation | [23] |
| No effect on resting (nonactivated) neutrophils | Reduces injury to host tissue | ||
| Macrophage | Promotes apoptosis of LPS-, IFN-γ, or LPS/ IFN-γ-activated macrophages | Reduces inflammation | [23,26,34,38] |
| No effect on resting macrophages | Reduces injury to host tissue | ||
| Promotes polarization of M1 (pro-inflammatory) macrophages to M2 (anti-inflammatory) macrophages | Removes inflammatory mediators and cell debris | ||
| Promotes macrophage phagocytosis of apoptotic neutrophils | |||
| Suppresses macrophage infiltration | |||
| T-Cell | Suppresses activation of CD4+T-cells | Reduces tissue inflammation in immunity and autoimmunity | |
| Promotes significant expansion of CD25+/FOXP3+T-cells Suppresses infiltration of CD45+CD4+IL-17+inflammatory immune cells |
Prolongs co-transplanted allograft survival | [38,83] | |
| Fibroblast | Downregulates TGF-β1, 2, and 3 and TGF-βR2 transcripts | Prevents scar formation | [26,39,46,47,48,49,50] |
| Suppresses TGF-β1 promoter activity | Prevents adhesion | ||
| Prevents pSMAD2/3 nuclear translocation | Promotes normal histologic structure and biomechanical strength | ||
| Reduces myofibroblast differentiation | Promotes range of motion and function | ||
| Suppresses CD45+CD34+collagen I+CXCR4+fibrocytes and HSP47+activated fibroblasts | Prevents structural degradation or failure | ||
| Myofibroblast | Reverses differentiated myofibroblasts back to fibroblasts without proliferation | Prevents scar formation and adhesion | [31,51] |
| Prevents expression of α-SMA | Reduces scarring | ||
| Promotes normal histologic structure | |||
| Retinal pigment epithelium | Suppresses proliferation of EGF/FGF-2-stimulated RPE |
Prevents proliferative vitreoretinopathy | [83] |
| Suppresses migration of TGF-β-stimulated human RPE |
Prevents scar formation | ||
| Prevents expression of α-SMA | |||
| Suppresses EMT of TGF-β-stimulated human RPE |
LPS=Lipopolysaccharide, IFN=Interferon, IL=Interleukin, TGF=Transforming growth factor, pSMAD=Phosphorylated Smad, EGF=Epidermal growth factor, FGF=Fibroblast growth factor, RPE=Retinal pigment epithelium, SMA=Smooth muscle actin, EMT=Epithelial–mesenchymal transition, fMLP=N-Formyl-methionyl-leucyl- phenylalanine, α-SMA=alpha-smooth muscle actin