Development of an in vitro 3D choroidal neovascularization model using chemically induced hypoxia through an ultra-thin, free-standing nanofiber membrane.

Choroidal neovascularization (CNV) is the pathological growth of new blood vessels in the sub-retinal pigment epithelial (RPE) space from the choroid through a break in the Bruch's membrane (BM). Despite its importance in studying biological processes and drug discovery, the development of an in vitro CNV model that achieves the physiological structures of native RPE-BM-choroidal capillaries (CC) is still challenging. Here, we develop a novel 3D RPE-BM-CC complex biomimetic system on an ultra-thin, free-standing nanofiber membrane. The thickness of the pristine nanofiber membrane is 2.17 ± 0.81 μm, and the Matrigel-coated nanofiber membrane attains a permeability coefficient of 2.95 ± 0.25 × 10^-6 cm/s by 40 kDa FITC-dextran, which is similar to the physiological value of the native BM. On the in vitro 3D RPE-BM-CC complex system, we demonstrate endothelial cell invasion across the 3D RPE-BM-CC complex and the mechanism of the invasion by imposing a hypoxic condition, which is thought to be the major pathological cause of CNV. Furthermore, alleviation of the invasion is achieved by treating with chrysin and anti-VEGF antibody. Thus, the in vitro 3D RPE-BM-CC complex biomimetic system can recapitulate essential features of the pathophysiological environment and be employed for the screening of drug candidates to reduce the number of costly and time-consuming in vivo tests or clinical trials.