Extracellular Matrix Expression in Human Induced Pluripotent Stem Cell-Derived Optic Vesicles

Background: Human tissue/organ development is a complex, highly orchestrated process, regulated in part by the surrounding extracellular matrix (ECM). Every complex tissue, including the retina, has a unique ECM configuration that plays a critical role in cellular differentiation, adhesion, migration, and maturation. Aim: To characterize ECM expression of human induced pluripotent stem cell-derived optic vesicles (iPSC-OVs). Methods: A 3- dimensional (3D) in vitro suspension culture system was used to direct differentiation of human induced pluripotent stem cells (iPSCs) into optic vesicles (OVs). Stepwise differentiation of iPSCs into retinal progenitor cells was confirmed by sequential expression of OTX2, SOX1, SIX6, LHX2, PAX6, and CHX10. Expression of ECM genes in iPSC-derived OVs was analyzed by RT2 ProfilerTM PCR Array, whereas immunofluorescence staining was performed to detect ECM proteins in the OVs. Results: A number of cell adhesion molecules (CAMs) previously reported to be abundantly expressed in iPSCs such as E-cadherin, Intercellular adhesion molecule-1 (ICAM1), Integrin-α L, Integrin-α M, Integrin-α 6 were downregulated while neural and retina specific CAMs including neural cell adhesion molecule 1 (NCAM1), neural plakophilin-related armadillo repeat protein (NPRAP), Integrin-α 1 and Integrin-α 4 were upregulated. Several glycoproteins that have been reported to play key roles during retinogenesis, namely CD44, Tenascin C, Tenascin R, Neurocan, Neuroglycan C, Delta 2 Catenin, Vitronectin, and Reelin were also present. Conclusion: We have identified an array of ECM proteins that were expressed during retinogenesis. Further characterization of these proteins will lead to a better understanding of retinal development.