In vitro characterization of micropatterned PLGA‐PHBV8 blend films as temporary scaffolds for photoreceptor cells

Abstract

In developed countries the aging population faces increasing risks of blinding retinal diseases, for which there are few effective treatments available. Photoreceptor transplantation represents one approach, but generally results have been disappointing. We hypothesize that micropatterned biodegradable poly(L-lactic acid-co-glycolic acid)/poly(hydroxybutyrate-co-hydroxyvaleric acid) (PLGA-PHBV8) blend films could deliver photoreceptor cells in a more organized manner than bolus injections. Blending of PLGA and PHBV8 was used to optimize the degradation rate of the temporary template. At the end of 8 weeks, for both thin and thick films of PLGA-PHBV8 a 50% decrease of their initial weight with increasing water uptake was observed. When photoreceptor cells were seeded onto micropatterned PLGA-PHBV8 films with parallel grooves (21- and 42-microm-wide grooves and 20 microm ridge width and depth), the cells preferred laminin-deposited grooves to ridges and expressed rod- and cone-specific markers such as rhodopsin and arrestin. A loss in photoreceptor viability of 50% was observed after 7 days in culture. The effects of either retinal pigment epithelium (RPE)-derived or Muller glial cell-derived conditioned media or bFGF on the survival of photoreceptor cells seeded on PLGA-PHBV8 films were investigated. Addition of either RPE- and Muller-conditioned media increased statistically (p < 0.01) the viability of photoreceptor cells after 7 days of incubation. Our results suggest that such biodegradable micropatterned PLGA-PHBV8 blend films have a potential to deliver photoreceptor cells to the subretinal space and ensure laminar organization and maintenance of differentiation, and that incorporation of intrinsic factors within the scaffold would enhance the survival rate of transplanted cells.

Differentiation of Induced Pluripotent Stem Cells to Neural Retinal Precursor Cells on Porous Poly-Lactic-co-Glycolic Acid Scaffolds

“…Although several groups have investigated the use of scaffolds isolated from donor tissue, in the retina, these approaches have only been successful for RPE cells and are limited by tissue availability. [19][20][21][22][23][24] Several synthetic materials have also been investigated for the purpose of supporting replacement cells during transplantation, including inorganic materials, PMMA, 21 poly(glycerol sebecate) (PGS), 24 and poly(caprolactone) (PCL). 25 However, by far, the most commonly investigated synthetic material is PLGA.…”

“…18 Furthermore, micropatterned PLGA has been shown to support the growth of primary photoreceptors for a short period of time-a strong indication of its promise as a retinal cell delivery scaffold. 19 In this work, PLGA scaffolds with randomly distributed pores were fabricated using a simple salt leaching technique. Although electrospinning, the most common PLGA processing technique, has been used extensively to create fibrous mesh scaffolds, it offers little in the way of precisely controlling pore size, as do techniques such as dioxane crystallization templating.…”

“…Furthermore, optimizing the porosity of a material could beneficially maximize the delivery of nutrients, oxygen, and/or water to surrounding cells and tissues. In fact, several studies have demonstrated the effects of porosity and other polymer structure on retinal cell/material interactions, including photoreceptor cell growth in grooves, 19 RPE cell growth on porous substrates, 20 and RPC growth and differentiation on porous materials. 18,21 However, to our knowledge, induced pluripotent stem cells (iPSCs) have never been differentiated toward retinal cell phenotypes on these materials, and the effects of pore size on proliferation and differentiation have yet to be characterized.…”

Polymer Thin Films for Biomedical Applications

“…Surfaces can provide physical and chemical guidance to growth and alignment of cells such as neurons, Schwann cells, epithelial cells, and bone -derived cells [229] . The " contact guidance " or mechanical cues provided by grooves on a polymer surface -and also the chemical cues offered by micropatterns of molecules that promote or prevent cell adhesion -have attracted great interest in biomedical engineering.…”

“…One interesting application of micropatterned polymer fi lms in tissue engineering is the use of a biodegradable thin and thick fi lm scaffolds prepared from a blend of poly( L -lactic acid -co -glycolic acid) and poly(hydroxybutyrate -co -hydroxyvaleric acid) [229] . The fi lms were prepared by casting a solution of the polymer blend onto a micropatterned silicon template that incorporated 21 μ m -and 42 μ m -wide grooves on the surfaces (with 20 μ m ridge width and depth).…”