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Annual Meeting SVGO / SBMS Thursday May 4th, 2017 Cellularized Perfusable Microvessels for the Study of Human Pericytes Response to Paracrine Signals AR Pereira 1, L Barbe 2, M Herrmann 1, M Alini 1, S Verrier 1. 1

AO Research Institute, Davos, Switzerland; 2 CSEM, Landquart, Switzerland.

Introduction: Pericytes (PCs) located on the outside of capillaries play a pivotal role in formation and stabilization of blood vessels and are suggested to contribute to regenerative processes [1]. However, the complex interplay between endothelial cells and pericytes is still incompletely understood. To access the response of pericytes to paracrine signaling (e.g. inflammation), here we developed a microfluidic perfusable 3D co-culture system for pericytes and human umbilical vein endothelial cells (HUVECs). Methods: The microfluidic platform comprises three different parts: a glass slide stage, a polycarbonate chamber including two capillary guides and a PDMS lid (Figure 1A). Type I-collagen (2.5 mg/ml) is poured in the chamber and polymerized at 37ºC for one hour. Two parallel microvascular channels are generated by gently retraction of microcapillaries. Each channel is individually connected to a reservoir of endothelial growth medium perfused using a piezoelectric micro-pump. GFP-HUVECs are injected into the channels and left to adhere for 16h. Cell-seeded microchannels are perfused under physiological conditions (≤10 μl/min) and observed using a time-lapse microscope. Seeding and co-culture protocols of PCs and HUVECs were optimized using a Vena8 Endothelial+™ biochip (Cellix). Results: The created channels showed regular and stable shape (diameter 150 μm) either in static or perfusion conditions (Figure 1B). The seeding procedure and perfusion conditions allowed for good cell viability and efficient endothelialization of the channel (Figure 1C). Using the cellix biochip, the coculture cell seeding protocol was optimized with the use of 4% dextran. In addition, compared to sequential cell seeding, direct co-seeding of both cell types in a 4:1 ratio (HUVECs:PCs) showed superior channel endothelialization (Figure 1D). Conclusion: We successfully produced on-chip perfusable micro capillary-like structures comprising endothelial cells and pericytes. Next, pericyte behavior and migration will be monitored in response to perfused paracrine factors. Acknowledgement: This work is supported by the AO Foundation and the 3R Research Foundation Switzerland (#139-14). [1] Crisan M. et al, Cell Stem Cell 2008. 3:301-313.

Figure 1 – A: Microfluidic platform. B: Perfusable microchannels. C: Cellularized microchannels. D: Co-culture on Cellix biochips.

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