• vascular microfluidic network
• in vitro model
• microfluidic device
• finite element modeling
• bioreactor
• blood-retinal barrier
• tissue engineering
• age-related macular degeneration

In order to investigate the pathophysiological process underlying age-related macular degeneration (AMD) and to validate novel drug candidates, several in vivo and in vitro models have been proposed. However, none of these has proven to be reliable to mimic the complex cellular interactions in the outer blood-retinal barrier (oBRB) with physiological realism and great predictive value. This thesis presents the design and fabrication of a novel oBRB-on-a-chip model as a biomimetic platform for AMD understanding and for new therapeutic agents development.
The device is a 3D microfluidic platform consisting of a biomimetic blood vessel network mimicking the choroidal vascular network (CVN) and of a novel engineered membrane mimicking the Bruch’s membrane (BrM) both housed within a single-chamber which resembles the intraocular space and enables the co-culture of human retinal pigment epithelium (RPE) and endothelial cells above the BrM and inside the CVN respectively. The microfluidic network, designed starting from medical images, was fabricated from polydimethylsiloxane (PDMS) through a novel manufacturing method established to provide a time-saving and cost-effective alternative to the common lithographic-based techniques. The interior surfaces of the microfluidic channels were subsequently coated with chemically crosslinked gelatin to promote cell adhesion and long-term culture. The engineered BrM was fabricated from chemically crosslinked gelatin by electrospinning process to get porous, ultrathin and nanofibrous membranes mimicking the mechanical, chemical and physical properties of the native substrate. The co-culture chamber with a common internal footprint with the wells in standard 24-well plates was fabricated from PDMS via the moulding process. Finite Element Analysis (FEA) was used for the understanding of the physical phenomena which occur inside the designed and fabricated bioreactor and for the validation of design approaches. Perfusion tests were successfully performed using the microfluidic platform. Human embryonic stem cell-derived RPE (hESC-RPE) cells and HUVECs cells were cultured on the engineered BrM and on PDMS-gelatin substrates respectively to evaluate cells adhesion and proliferation under static conditions. Immunofluorescence techniques and optical microscope observation demonstrated that engineered BrMs supported functional RPE monolayer formation, while HUVECs cells shown good adhesion and proliferation on the PDMS-gelatin substrates. Tests of dynamic seeding and static/dynamic co-culture tests were performed with the HUVECs cells.