Bioinspired hydrogel surfaces to augment corneal endothelial cell monolayer formation

Abstract

Corneal endothelial cells (CECs) have limited proliferation ability leading to corneal endothelium (CE) dysfunction and eventually vision loss when cell number decreases below a critical level. Although transplantation is the main treatment method, donor shortage problem is a major bottleneck. The transplantation of in vitro developed endothelial cells with desirable density is a promising idea. Designing cell substrates that mimic the native CE microenvironment is a substantial step to achieve this goal. In the presented study, we prepared polyacrylamide (PA) cell substrates that have a microfabricated topography inspired by the dimensions of CECs. Hydrogel surfaces were prepared via two different designs with small and large patterns. Small patterned hydrogels have physiologically relevant hexagon densities (∼2000 hexagons/mm2), whereas large patterned hydrogels have sparsely populated hexagons (∼400 hexagons/mm2). These substrates have similar elastic modulus of native Descemet's membrane (DM; ∼50 kPa) and were modified with Collagen IV (Col IV) to have biochemical content similar to native DM. The behavior of bovine corneal endothelial cells on these substrates was investigated and results show that cell proliferation on small patterned substrates was significantly (p = 0.0004) higher than the large patterned substrates. Small patterned substrates enabled a more densely populated cell monolayer compared to other groups (p = 0.001 vs. flat and p < 0.0001 vs. large patterned substrates). These results suggest that generating bioinspired surface topographies augments the formation of CE monolayers with the desired cell density, addressing the in vitro development of CE layers.

Unraveling the mechanobiology of cornea: From bench side to the clinic

“…Both micro- (∼1 µm) and nano-sized (∼250 nm) pillars were found to facilitate the in vivo -like morphology of CEnCs, promote their proliferation with higher cell density and smaller cell size ( Muhammad et al, 2015 ; Rizwan et al, 2017 ), and enhance the expressions of Na + /K + ATPase and cell–cell tight junction protein Zonula Occludens-1 (ZO-1) ( Koo et al, 2014 ; Muhammad et al, 2015 ; Palchesko et al, 2015 ; Rizwan et al, 2017 ). Recently, a small patterned hydrogel surface with physiologically relevant hexagon densities (∼2000 hexagons/mm 2 ) and a similar elastic modulus to native Descemet’s membrane (∼50 kPa) was constructed and augmented the formation of monolayers with higher cell density ( Erkoc-Biradli et al, 2021 ). In addition, substrates with hexagonal microtopography can promote differentiation of human mesenchymal stem cells into corneal-endothelial-like cells ( Gutermuth et al, 2019 ).…”

Rose petal topography mimicked poly(dimethylsiloxane) substrates for enhanced corneal endothelial cell behavior

“…Furthermore, in our previous work, we prepared hexagonal wellpatterned polyacrylamide (PA) cell substrates via bioinspiration approach to enhance CEC proliferation. Substrates with physiologically relevant pattern density provided the most favorable cellular results in terms of cell density and cell proliferation [74]. In addition to abovementioned cell substrates, several substrate materials such as polyurethane, silicon surfaces, polycaprolactone, chitosan, polystyrene with various feature type and dimensions were studied for corneal stromal or epithelial cell types to examine the effect of topography [73].…”

Cell therapy in corneal endothelial disease

“…There is an extensive list of bioengineered materials -whether biomaterials or synthetic polymers -that have been investigated for use as a scaffold [54][55][56][57]. These include amniotic membrane, decellularized tissue such as human DM, corneal stroma, lens capsule, porcine or bovine corneal posterior lamellae [58], silk fibroin, gelatin [59,60], hydrogel [61], collagen, chitosan, agarose and poly-e-lysine [55]. A study comparing four types of electrospun nanofibre scaffolds found that blended polycaprolactone (PCL)/ collagen and PCL/gelatine were associated with significantly higher CEC viability compared with PCL alone, and PCL/chitosan [62].…”