Complement activation in the context of stem cells and tissue repair

Table 1 Cell types expressing the C3aR and the C5aR and their function

Cells expressing C3aR	Function of C3aR	Cells expressing C5aR	Function of C5aR
Neutrophils[244]	Respiratory burst[26], bone marrow retention in vivo[189]	Neutrophils[245]	Respiratory burst[28], chemotaxis[24], enzyme release[127]
Eosinophils[30]	Chemotaxis[30], in vitro but not in vivo[25]	Eosinophils[246]	Respiratory burst[27], chemotaxis
Monocytes/macrophages[31]	Chemotaxis[247], cytokine/chemokine production[164]	Monocytes/macrophages	Chemotaxis[104,248], cytokine/chemokine production[164]
Mast cell	Mediator release[102], chemokine production[249], chemotaxis [100,101]	Mast cell	Mediator release[102], chemokine production[249], chemotaxis[100,101]
Small fraction of lymphocytes[250,251]	Complex in vivo functions[252]	Small fraction of lymphocytes[251,253]	Complex in vivo functions
Osteoblasts[155,173,254]	Chemotaxis, accelerated osteogenesis, improved bone healing in vivo[174]	Osteoblasts[97,173]	Chemotaxis[97], accelerated osteogenesis[175], improved bone healing in vivo[174]
Chondrocytes[172]	Osteogenic differentiation (?)	Chondrocytes[172]	Osteogenic differentiation (?)
Tenocytes[46]	Not clear	Tenocytes[46]	Not clear
Smooth muscle cells[51]	Increased mediator release from mast cells[255]	Smooth muscle cells[44,51]	Not clear
Endothelial cells[52]	Transient ERK and rho activation[52], cytokine production[53]	Endothelial cells[52]	Chemotaxis[52], increased permeability[52] cytokine production[53], proliferation[128]
Hepatocytes[88]	Protection from apoptosis[88], liver regeneration in vivo[87,88]	Hepatocytes[44]	Proliferation[58], protection from apoptosis liver regeneration in vivo[87,94]
Renal epithelial cells[256]	Chemokine production[257], EMT under stress conditions[258]	Renal epithelial cells	EMT under stress conditions[259]
Neurons[193]	Protection from cell death[193,199]	Neurons[194]	Protection from cell death[193-195]
Astrocytes[260]	Indirect neuroprotection[198], NGF expression[200]	Astrocytes[261]	Cytokine and NGF expression[200,262]
MSC[61,90]	Chemotaxis[61], protection from apoptosis[61], production of angiogenic factors[91]	MSC[61,90]	Chemotaxis[61], protection from apoptosis[61], production of angiogenic factors[91]
HSPC[59]	Enhanced effects of SDF-1[263], improved bone marrow engraftment[60,188]	Not expressed	Indirect: decreased mobilization[192]; indirect: improved bone marrow engraftment[191]
CSPC[182]	Chemotaxis[182], proliferation[182]	CSPS[182],	Chemotaxis[182], proliferation[182] cardiac dysfunction in C5/C5aR -/- mice[180]
NSPC[2]	Increased neurogenesis[2], chemotaxis and differentiation[89]	NSPC[2]	Increased neurogenesis[2]
ESC	Not expressed	ESC	Prevents differentiation[168]

ERK: Extracellar signal-regulated kinase; EMT: Epithelial-to-mesenchymal transformation; NGF: Nerve growth factor; MSC: Mesenchymal stem cells; SDF: Stromal-cell derived factor; HSPC: Hematopoietic stem and progenitor cells; CSPC: Cardiac stem and progenitor cells; NSPC: Neural stem and progenitor cells; ESC: Embryonic stem cells; MAC: Membrane attack complex.