A unique aged human retinal pigmented epithelial cell line useful for studying lens differentiation in vitro.

Lens regeneration occurs in some urodeles and fish throughout their adult life. Such an event is possible by the transdifferentiation of the pigment epithelial cells (PECs) from the dorsal iris. Studies of this event at the cellular level have been facilitated owing to the ability of PECs to become lens cells even when they are placed in culture, outside of the eye. In fact, PECs possess the capacity for transdifferentiation regardless of the origin of species or age. However, studies at the molecular level are still hindered by the intrinsic problems of primary cultures, namely storage, reproducibility and genetic manipulation. In an attempt to establish an ideal model system for lens transdifferentiation, we have analyzed the ability of a human dedifferentiated PEC line to differentiate into lens. We have found that this cell line can indeed be induced to synthesize crystallin and morphologically differentiate to three-dimensional structures resembling lentoids under controlled treatment in vitro. Gene expression studies also provided important insights into the role of key genes. This human cell line can be used for detailed genetic studies in order to identify the key factors involved in lens transdifferentiation from PECs.