Abstract
Purpose: :
Cell transplantation is one of the most promising strategies for photoreceptor replacement. However, integration into the outer nuclear layer and differentiation into new photoreceptor remain a challenge. In this study, biodegradable thin-film polycaprolactone (PCL) scaffolds were developed to guide cell differentiation.
Methods: :
Micro and nano-electro-mechanical systems techniques with a novel templating process were used to create these thin-film PCL scaffolds with topography of ridge-groove (RG) or post (P), and compared to smooth PCL (S) and glass (G) controls. 100 µl of mouse retinal progenitor cell (mRPC) suspension (8×104 cells) was seeded onto each PCL scaffold or glass and cultured for 7 days. Cell morphology, protein expression level and mRNA expression level were examined by scanning electron microscopy, immunocytochemistry (ICC) and reverse transcription polymerase chain reaction (RT-PCR), respectively.
Results: :
After plating, the morphology of mRPCs appeared to change to adapt to the topography of PCL scaffolds. The most pronounced morphological changes occurred in mRPCs cultured on PCL scaffolds with ridge-groove. These cells developed substantial elongation and parallel alignment. ICC demonstrated that mRPCs grown on PCL scaffolds had the potential to differentiate into photoreceptors, expressing photoreceptor markers. A significant increase (p<0.001) of crx-, recoverin- and rhodopsin-positive cells was detected in mRPCs grown on PCL scaffolds compared to glass (Crx%: G 11.63±2.32, S 77.88±6.20, RG 81.02±4.90 and P 79.78±6.91; Recoverin%: G 17.29±5.69, S 77.51±9.01, RG 80.52±7.37 and P 82.56±4.68; Rhodopsin%: G 10.99±3.79, S 74.81±8.62, RG 79.49±7.17 and P 74.52±9.98). However, no difference was seen among different topographies. RT-PCR demonstrated higher gene expression of these photoreceptor markers in mRPCs grown on PCL scaffolds than those grown on glass. Although there were differences in these markers among different topographies of PCL scaffolds, only rhodopsin expression was significantly upregulated (p<0.05).
Conclusions: :
These biodegradable thin-film PCL scaffolds could direct the differentiation of mRPCs in a controlled manner, providing a useful platform for retinal regeneration.Copyright © 2010 by The Charles Stark Draper Laboratory, Inc and Schepens Eye Research Institute all rights reserved.
Keywords: differentiation • photoreceptors • retina