Abstract
Purpose: :
Retinal degenerations cause permanent visual loss and affect millions of people worldwide. Previous work has demonstrated the utility of using biodegradable polymer scaffolds to induce differentiation and deliver retinal progenitor cells for cell replacement therapy. In this study, we engineered a biodegradable polycaprolactone (PCL) thin film scaffold with integrated sub-micron topography and analyzed its effect on the differentiation of human retinal progenitor cells (hRPCs).
Methods: :
The PCL polymer was microfabricated with ridge-grooves or posts on the surface. hRPCs were isolated from human retina of 14 to 18 weeks gestational age and expanded in vitro, in low-tension oxygen (3%). At passage five the cells were seeded in an 8-well slide (control group) and on three different types of PCL scaffolds (smooth surface, ridge-groove and post). After one-week, real time polymerase chain reaction (PCR) and immunocytochemistry (ICC) assays were performed on hRPCs cultured on the biodegradable polymer and on the control group, in order to evaluate the differentiation of hRPCs into photoreceptors. Explant experiments and subretinal transplantation of pre differentiate hRPCs were performed to analyze the cell migration and integration into the host retina of rhodopsin -/- mice.
Results: :
Microfabricated topography in a PCL thin film enhanced the attachment and organization of hRPCs compared to unstructured surfaces. hRPCs adherent to PCL differentiated toward mature photoreceptor phenotypes as evidenced by changes in mRNA and protein levels. Using real time quantitative PCR and ICC we observed a statistically significant upregulation in the expression of rhodopsin, CRX, recoverin and a statistically significant downregulation in SOX2 (a marker for undifferentiated progenitor cells) and PAX6 compared to cells grown on polystyrene. Additionally, transplanted pre differentiated hRPCs migrated into the outer nuclear layer of the host retina and exhibited mature marker photoreceptor expression.
Conclusions: :
This unique structured PCL thin-film scaffold provides a means to organize and differentiate RPCs in a controlled manner. Moreover the pre differentiate cells were able to integrate into a degenerated host retina.