Therapeutic potential of adipose tissue derived mesenchymal stem cells for AMD - migration, trophic anti-angiogenic effects and differentiation

Abstract

Purpose: Hypoxic stress contributes to RPE dysfunction in AMD. We aimed to examine the paracrine activity and differentiation potential of adipose tissue derived mesenchymal stem cells (ASCs) when exposed to hypoxic and normoxic retinal pigment epithelium (RPE) in vitro.

Methods: In order to mimic AMD environment, RPE cells were subjected to 1% O₂ hypoxia. First, migratory capacity of ASCs towards hypoxic RPE conditioned medium was examined by Transwell migration assay. Then, to investigate the paracrine activity of these cells, ASCs were cultured with RPE conditioned medium; Expression of growth factors, chemokine receptors and angiogenic agents were studied by qRT-PCR and immunostaining. Additionally, differentiation capacity to RPE was examined by culturing ASCs with RPE conditioned medium, activin A and nicotinamide. Differentiation markers were assessed with qRT-PCR and immunostaining.

Results: ASCs exhibited enhanced migration towards hypoxic RPE (3.4 folds ±0.37 p<0.0009) when compared to normoxic RPE, by upregulation of CXCR4 (9.5 folds±0.17 p=0.002). ASCs increased expression of the trophic factor BDNF (2.2±0.3 folds p<0.05) and anti angiogenic agent serpinb5 (2.3±1.6 folds p<0.05) when exposed to hypoxic RPE. ASCs demonstrated differentiation potential to RPE by upregulation of early eye field markers (pax6 2.6±0.8, six3 1.4±0.7, rax 1.4±0.2, otx2 2.2±0.7 folds) at 1-2 weeks and RPE markers (rlbp1 3.8±0.7, best1 2.3±0.7, emmprin 2±0.2, zo-1 2.2±0.4, tyrosinase 5.5±0.8, RPE65 3.8±1.6 folds) at 4 weeks.

Conclusions: ASCs migrate towards hypoxic RPE and secrete trophic and anti angiogenic factors. ASCs also exhibit differentiation capacity to RPE. These data may imply to a therapeutic potential of ASCs when exposed to hypoxic RPE.