Extracellular matrix proteins as substrate modulate the pattern of calcium channel expression in cultured rat retinal pigment epithelial cells

Abstract

We investigated the effect of different culture substrates on the expression of membrane conductances for calcium in cultured rat retinal pigment epithelial (RPE) cells using the perforated patch technique and barium as charge carrier. In younger cultures (up to 12 days old) the RPE cells expressed L-type calcium channels, in older cultures (more than 12 days old) LVA-type channels. The LVA-type channels have been characterized as a tetrodotoxin sensitive Ca2+ channels. Coating the culture substrate with laminin, shifted the culture age for expression of LVA-type channels to 7 days. When collagen type 4 was used as substrate LVA-type channels and L-type channels were expressed simultaneously in 7 days old cultures. We concluded that proteins of the extracellular matrix which are known to enhance cell differentiation in culture, enhance the expression of LVA-type channels in RPE cells.

Physiological features of primary cultures and subcultures of human retinal pigment epithelial cells before and after cryopreservation for cell transplantation

“…2) maintain their differentiated state after primary culture and after cryopreservation. This was not the case when conventional culture techniques were employed [26,27]. Our former studies also demonstrated that optimized in vitro growth conditions for RPE cells resulted in an increased expression of typical MHC class I and class II antigens compared to conventional culture conditions employing only basal medium + FCS (36% vs 74%) [24].…”

“…HLA typing was performed again and compared with the previous results with regard to completeness and correspondence. Patch-clamp experiments were performed according to previously described methods [11,26,27]. Cells were investigated for the expression of Ca 2+ channel types in the first passage after cryopreservation.…”

“…In this study we investigated wether cells cultured under optimized culture con-ditions retain their typical MHC antigen expression after subculturing and cryopreservation. Recently, we showed that changes in the expression of Ca 2+ channels in RPE cells can be used to describe the state of differentiation of the cultured RPE cells [26][27][28]. RPE cells express different L-type Ca 2+ channels (low-and high-threshold channels) during culture which are typical for isolated RPE cells from various species [26,27,31,32].…”

Effect of Extracellular Matrix Elements on Angiotensin II–Induced Calcium Release in Vascular Smooth Muscle Cells From Normotensive and Hypertensive Rats

“…9,10,46,47 Cell surface receptors for ECM are frequently members of the integrin family, transmembrane glycoproteins containing an ␣-and a ␤-subunit. Integrinmediated signaling involves tyrosine kinase activity associated with focal adhesions.…”

Cell culture conditions affect RPE phagocytic function

“…RPE cells in vitro in particular undergo immediate changes in morphology, melanization and protein expression [42,52,53]. For example, a change in vital RPE polarity [2,57] and alteration or loss of signal pathways such as ion channel expression have been observed during culture [48,54]. Furthermore, it has been shown that phagocytosis rates depend both on the RPE cell phenotype [14,31] and the growth surface [33].…”