Table 1.

Factors and pathways that affect MSC migration during bone formation.

Factor	Ossification Pattern	Pathway	Efficacy	In Vitro or In Vivo	Reference
BMPs	Endochondral	Activate SMADs receptor to	MSC condensation	In vitro	[21]
		transduce signals	Recruitment of osteoblast
Hoxa13 and	Endochondral	Promote cell-cell adhesion	MSC condensation	In vitro	[22]
Hoxd13			Bone formation
ECM	Endochondral	Self-assembling of MSCs	MSC condensation	In vitro	[23]
LL-37	Intramembranous	MAPK pathway	Expression of EGR1	In vitro and in vivo	[24]
			Activation of MAPKs
PDGFs	Intramembranous	BMP-Smad1/5/8-Twist1/Atf4 axis	Cell migration	In vitro	[25]
TGF-β1	Intramembranous	SMAD signaling	Cell migration	In vitro and in vivo	[26]
MMP	Intramembranous	Penetrate blood vessel basement membranes	Induce MSC migration	In vitro and in vivo	[27,28]
NF-κB ligand	Intramembranous	Activating phosphorylation of ERK, MAPK, Akt, and NF-κB	Cell migration	In vitro	[33]
TNFα	Fracture healing	Induce LRG1 secretion	MSC recruitment	In vitro and in vivo	[40]
CXCL7	Fracture healing	Binding CXCR2	MSC recruitment	In vitro	[36]
SDF-1	Fracture healing	Binding CXCR4	Osteoblast migration	In vitro and in vivo	[41]
			MSC recruitment

: Up-regulation.