Abstract
Purpose:
Physiology of retinal pigment epithelium (RPE) is determined by the activity of various ion channels, and especially important is the role of calcium for RPE functionality. Calcium signaling is associated to several important RPE functions, such as transepithelial transport of ions and water, dark adaption of photoreceptor activity, phagocytosis, secretion, and differentiation. In this study, we characterized the voltage-dependent calcium currents in human embryonic stem cell (hESC) derived RPE cells by patch clamp technique. More information about the functionality of stem cell derived RPE cells is needed as they provide a potential therapeutic approach for the treatment of several degenerative eye diseases.
Methods:
The pluripotent embryonic cell lines were derived and maintained using existing protocols in the laboratory of Heli Skottman (Tampere, Finland). The differentiation of RPE from pluripotent hESCs was performed in the Skottman laboratory as described before. The calcium currents were characterized by whole-cell patch clamp recordings of mature hESC-RPE monolayers showing pigmentation and typical cobblestone morphology.
Results:
Whole-cell voltage-clamp recordings demonstrated a heterogeneous pattern of voltage-dependent calcium channels in hESC-RPE. Some cells showed sustained high-voltage-activated currents resembling L-type calcium channels whereas other cells showed transient currents typical to T-type calcium channels.
Conclusions:
Our results indicate the presence of at least two types of calcium channels in hESC-RPE. The observed L- and T-type currents are comparable to the recordings of RPE from multiple species in the literature.
Keywords: 508 electrophysiology: non-clinical •
701 retinal pigment epithelium •
439 calcium