Abstract
Purpose :
Reductionist approaches into mechanisms underlying diseases of the outer blood-retinal-barrier (oBRB), such as age-related macular degeneration and diabetic retinopathy (DR) have been hampered by the lack of optimal in vitro models utilizing human cells to provide the 3-D dynamic architecture and allow expression of the in vivo phenotype for both the retinal pigment epithelialium (RPE) and the choroidal endothelium (EC). The main limitations of the current oBRB models also arise from the cell sourcing, the lack of a proper Bruch s membrane (BM) analogue, and lack of choroidal microvasculature with flow. Therefore, we aimed to develop an oBRB-on-a-chip biomimetic system to emulate the cellular interactions that occur in retinal inflammatory disorders.
Methods :
We have generated a macrofluidic device that allows the simultaneous co-culture of RPE with perfusable EC. Taking advantage of the differentiation potential of human pluripotent stem cells (hPSC), we optimized differentiation protocols to obtain hPSC-RPE and hPSC-EC from hPSC. On the other hand, by combining biomaterial engineering and decellularization protocols we designed a BM analogue that favors the co-culture of hPSC-RPE and hPSC-EC.
Results :
Differentiated hPSC-RPE showed a phenotype similar to that of mature RPE, while differentiated hPSC-EC showed a mature endothelial phenotype as they showed tubulogenesis properties and expressed endothelial markers. The co-culture of EC with hPSC-RPE cells increased the RPE barrier functional activity, significantly increasing TEER and decreasing the basolateral secretion of VEGF. On the other hand, we developed a decellularization protocol to obtain decellularized BM (dECM-BM) that guarantees DNA removal while preserving collagen and elastin fibers. Moreover, the BM analogue successfully allowed the co-culture of EC and hPSC-RPE cells Finally, we challenged the oBRB model with glucose oscillations and recapitulated the DR microenvironment.
Conclusions :
Our oBRB biomimetic co-culture system recapitulates the complex cellular interactions of the oBRB, inducing an increased RPE barrier functional activity, and allowing for the emulation of inflammatory microenvironments occurring during retinal disease. Overall, this human oBRB in vitro model represents an optimal platform to study the inflammatory processes underlying retinal pathologies.
This is a 2021 ARVO Annual Meeting abstract.