ABSTRACT
Objective:To explore the effect of upregulating CXC-chemokine receptor 7 (CXCR7) in endothelial progenitor cells (EPCs) on angiogenesis after cerebral ischemia-reperfusion injury. Methods:EPCs were isolated and cultured from human umbilical cord blood and identified. Then, the EPCs were transfected with CXCR7 overexpression lentiviral vector, and the expression of CXCR7 was identified with real-time PCR and Western blotting. The tube-like structure formation and apoptosis of EPCs under oxidized low density lipoprotein (ox-LDL) were detected with tube-like structure formation test and Annexin V/PI staining. Cerebral ischemia-reperfusion injury model in rats was established, and the qualified model rats were randomly divided into three groups after 24 hours reperfusion: PBS group (n = 12) was injected with phosphate buffers through tail vein, control group (n = 12) was injected the EPCs infected with control lentiviral vector, and CXCR7 group (n = 12) was injected with EPCs infected with CXCR7 overexpression lentiviral vector. Neurological function scores were determined seven and 14 days after transplantation. The cerebral infarct volume was measured, the number of GFP-positive cells in the ischemic site and the density of capillary were observed. Results:The expression of CXCR7 in EPCs increased after transfection (P < 0.01). Overexpression of CXCR7 improved tube formation and reduced apoptosis of EPCs under ox-LDL (P < 0.05). Compared with PBS and control groups , neurological function improved in CXCR7 group, with less infarct volume, more GFP-positive cells and density of capillary (P < 0.05). Conclusion:Up-regulating CXCR7 can improve the survival and angiogenesis of EPCs, and improve the repair of cerebral ischemia-reperfusion injury.
ABSTRACT
Objective To develop a microfluidic device with the adjustable concentration and pressure gradient for 3D cell culture in hydrogel and set up an in vitro model with the capability to closely simulate in vivo microenvironment for cell growth. Methods The microfluidic chip, with a middle channel for 3D cell culture and two side channels for delivering cell culture medium, was designed and fabricated using standard soft lithography and replica molding techniques. Its capability to generate concentration gradient, interstitial flow and image cell in situ was demonstrated. Results A simple microfluidic chip for 3D cell culture in hydrogel with the capability to generate the concentration and pressure gradient was obtained. At a flow rate of 2 μL•min-1 in each side channel, the concentration gradients remained constant after 3 h. The interstitial flow across the gel scaffold was generated by a 100 Pa pressure difference between two-side channels with the pressure gradient of 0.11 Pa/μm. Human adult dermal microvascular endothelial cells (HMVEC) were maintained in 3D culture with collagen type I and observed with confocal microscopy. Conclusions The microfluidic chip is simple and easy to operate and it can simulate the complicated microenvironment in vivo. The chip also allows the multiparameter control of microenvironment, facilitating the better understanding of interaction between cells and microenvironment.