Introduction: Artificial blood contacting metal prostheses such as stents are widely applied in clinical treatment of cardiovascular diseases. For overcoming the issue of the surface induced thrombosis and the in-stent restenosis of vessel, in-situ rapid endothelium regeneration inside the damaged vascular vessel is regarded as the most effective approach. Due to the key role of materials surface properties contribute to the in vivo mobilization, targeted migration, homing and directed differentiation of pluripotent stem cell, construct a biomimetic microenvironment on materials surface is suggested to be a breakthrough in induced endothelium regeneration [1],[2]. Here, a functional microenvironment were designed with key molecular in cellular response [3], along with vascular endothelial growth factor (VEGF), to realize the rapid endothelium regeneration by facilitating cell chemotactic and homing.
Materials and Methods: The obtained electronegative Ti surface by Alkali activation was deposited with dopamine (DM). The Hep and VEGF were firstly mixed. PLL was chronologically introduced to it to form nanoparticles (NP). Then, the nanoparticles were fixed to the modified Ti surface to construct biomimetic microenvironment. It was characterized by AFM, ELISA, and Alcian Blue etc. The ability of induced endothelialization was evaluated by in vitro chemotactic experiment. The cell-derived and homing behaviors were investigated by a new developing ex vivo animal models. The in-situ endothelium regeneration was furthermore tested by in vivo animal experiment.
Results and Discussion: Fig.1 displays the EPC chemotactic behavior of different samples surface with crystal-violet-staining method. In the small chemotactic room, the microenvironment of nanoparticles loaded VEGF has affected the chemotactic behavior of EPCs, obviously. The numbers of EPCs, which through the semipermeable membrane to the bottom of small room, are much higher than that of the DM and DM - NP after cultured 24 hours. The result demonstrates that the EPCs possess large spreading area, a good proliferation and morphology on the DM - NPV microenvironment.
Fig.2 is a schematic view of the ex vivo animal experiment model for endothelial progenitor cell capturing and homing. The healthy New Zealand white rabbit (4 to 6 kg) was chosen in the ex vivo circulating experiment. The jugular arteriovenous shunt method was used. Blood flow from the carotid artery (a) of rabbit to the jugular vein (b) through the ex vivo experimental device. The sample material is placed in the silicone catheter(c).
Conclusion: All the results indicated that, the loaded VEGF nanoparticles promoted the mobilization of EPCs, and obviously induced the EPCs migration to the source of VEGF for homing. The biomimetic microenvironment with loaded VEGF nanoparticles provides a way for the rapid endothelium regeneration.
This work was financially supported by the Key Basic Research Project (No. 2011CB606204#), and the National Natural Science Foundation of China (No.31170916#, No.31470921#).
References:
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[2] Tao Liu, Zhen Zeng, Jian Wang, Yang Liu, Yuan Wang, Manfred Maitz, Shihui Liu, Junying Chen*, Nan Huang, Surface modification with Dopamine and Heparin/Poly-l-lysine nanoparticles provides a favorable release behavior for the healing of vascular stent lesions, ACS applied materials & interfaces, 6(11)(2014)8729-8743
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