A Biodegradable Thin-film Polycaprolactone Scaffold As A New Tool To Enhance Differentiation Of Mouse Retinal Progenitor Cells

Abstract

Purpose: : Deterioration of the retinal microenvironment in advanced stages of age-related macular degeneration and the lack of signaling cues for proper cell organization and differentiation are significant challenges highlighting the need for a tissue-engineering approach to retinal regeneration. In this study, biodegradable thin-film polycaprolactone (PCL) scaffolds were developed as a new tool to guide retinal progenitor cell differentiation.

Methods: : PCL scaffolds with different nano-topographies were constructed using standard micro-electro-mechanical system techniques. 100 μl of mouse retinal progenitor cell (mRPC) suspension (8x10⁴ cells) was seeded onto each PCL scaffold and cultured for 7 days. These mRPC/PCL scaffold constructs were then cut and placed onto the outer surface (sub-retinal) of each retinal explant for 1 week or transplanted into the subretinal space of Rho-/- mice or C57bl6 mice for 3 weeks.

Results: : Compared to glass or polystyrene, mRPCs cultured on these PCL scaffolds altered morphology in response to the nano-topography and showed higher expression of photoreceptor markers. After 7-day co-culture, these mRPCs migrated extensively and took up residence in all retinal layers. mRPCs delivered via PCL scaffolds achieved better integration and more cells were integrated into both the outer nuclear layer (ONL) and the inner nuclear layer than single cells (S) (ONL: S: 8.17±2.69; PCL: 22.67±5.60 (p<0.001); INL: S: 14.08±4.44; PCL: 27.33±5.48 (p<0.001); RGC: S: 2.42±0.90; PCL: 3.75±1.14 (p=0.959)). 3 weeks post transplantation, the scaffold constructs remained flat in the subretinal space and no evident disarrangement of the host retina was detected. Some mPRCs migrated into the host retina. Both in retinal explant and subretinal transplantation, cells that migrated into the ONL could express photoreceptor markers and some began to resemble photoreceptor cells with newly formed outer segments. Some cells were able to make contact with host PKC positive bipolar cells and expressed synapse markers.

Conclusions: : PCL scaffolds provide a new platform to organize, differentiate and deliver mRPCs in a controlled manner, suggesting a promising strategy to address critical biological constraints related to retinal regeneration.

Keywords: regeneration • retina • topography