Characterization of chloride channels in human embryonic stem cell derived retinal pigment epithelium

Abstract

Retinal pigment epithelium (RPE) is vital for vision. Its ion channels play important roles in the various functions of RPE that are critical for retinal welfare. These functions are often disrupted in degenerative eye diseases leading to visual impairment and even blindness. New treatments are currently being developed and transplantation of human embryonic stem cell (hESC)-derived RPE is showing great promise. For the success of these therapies, functionality of the transplantable cells needs to be verified. Presence of ion channels in hESC-derived RPE remains poorly known, particularly regarding the various chloride (Cl-) channels. We addressed this issue by investigating the Cl- conductivity of hESC-derived RPE by whole-cell patch clamp recordings followed by immunolabeling of the Cl- channels typical to RPE. Our recordings showed a diverse pattern of slowly inactivating currents characteristic to voltage-dependent Cl- channels (ClC) previously reported for RPE. Some of the identified currents were modulated by changes in intracellular calcium concentration. This data, together with the immunolabeling, demonstrated the presence of bestrophin-1, cystic fibrosis transmembrane regulator (CFTR) and ClC-2 channels in hESC-derived RPE thus indicating their capability to mimic native Cl- physiology.