TABLE II.

State of art in microfluidic flow-based gradient devices and their biological applications.

Biological application	Cell type	Stimuli	Microfluidic platform	Reference
Cancer chemotaxis	Prostate cancer cells (PCC)	Chemokine gradient	A PDMS microfluidic device	54
	Breast cancer cells (MDA-MB-231)	EGF	Parallel gradient microfluidic chamber	55 and 63
Dendritic cell migration	Murine dendritic cells	Lymphoid chemokine CCL-19	Agarose-based microfluidic platform	56
Neutrophil chemotaxis	Peripheral blood neutrophils	N-fMLP	Kit-on-a-lid-assay (KOALA microfluidic devices)	57
Endothelial cell chemotaxis	Human umbilical vein endothelial cells (HUVEC)	Vascular endothelial growth factor (VEGF)	PDMS microfluidic device	58
Stem cell differentiation	Human bone marrow derived MSCs	Platelet-derived growth factor BB (PDGF-BB)	Microfluidic gradient device combined with ALZETH osmotic pumps	62
Migration of fibroblast cells	HFF-1 fibroblasts (SCRC-1041)	EGF	PDMS microfluidic device	63