Retinal pigment epithelium – choroid organ culture

www.expert-reviews.com ISSN 1746-9899 © 2011 Expert Reviews Ltd 10.1586/EOP.11.70 The retinal pigment epithelium (RPE) is a cellular monolayer between the neural retina and Bruch’s membrane. It adheres to and interacts with the underlying Bruch’s membrane at its basal side and with the photoreceptor outer segments at its apical side. It contributes to a turnover of photoreceptor outer segment, and thus the loss of RPE function may directly cause the loss of visual function. Along with increasing diagnostic and therapeutic methods, we now have the opportunity to explore the functions or the responses of the RPE; for example, the cellular response to the newly introduced intraocularly injected medicines such as anti-VEGF antagonists or the responses following new laser therapies. Cell culture technique has shown remarkable progress since the 1960s. Basic research with RPE cell culture has been extensively carried out and abundant experimental data have been provided to date. Experiments with monolayer RPE cells on plastic culture dishes or membrane filters have advantages in handling, preservation, stability and experimental repeatability, and is therefore now an essential method for basic scientific research on RPE. For the cell culture study, ARPE-19, a human RPE cell line, and mammalian RPE primary cell cultures are mostly used. RPE–choroid organ culture is a culture method to preserve RPE–choroid tissue explants for a certain time period in culture medium. RPE adheres to Bruch’s membrane, and morphological and functional cell polarity is well preserved in explant tissue compared with cell culture. The role of Bruch’s membrane in the pathogenesis of age-related chorioretinal diseases has been paid more attention recently, therefore studying with RPE on natural Bruch’s membrane has a big advantage in understanding age-related cellular changes. RPE–choroid tissue explants have been utilized as an experimental model mostly for RPE morphology and physiology since the 1970s. It has also been used in other studies, such as studies on phagocytosis activity and wound-healing responses of RPE. In addition to the conventional method to preserve the tissue explant in a static culture medium, the perfusion culture system has been recently introduced and provides the tissue with a better organotypical culture environment. This review article describes basic biological properties of RPE–choroid organ culture in comparison to RPE cell culture. Advantages and disadvantages of RPE–choroid organ culture as well as its future prospects are discussed, along with the discussion of recent studies.