| Budget Amount *help |
¥3,400,000 (Direct Cost: ¥3,400,000)
Fiscal Year 2002: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 2001: ¥2,800,000 (Direct Cost: ¥2,800,000)
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| Research Abstract |
In the clinical treatment for retinal degenerative disease, iris pigment epithelial cells (IPE) are possible substitutes for retinal pigment epithelial cells (RPE) for transplantation into the subretinal space. It was known that inward rectifier potassium (Kir) channel subunit Kir7.I is functionally expressed in the RPE, plays a central role for maintaining subretinal environment, and has some unique properties which differ from other retinal cells. In the present study, the expression and functional properties of the porcine IPE were investigated, and compared with those in the RPE.
IPE and RPE were acutely dissociated from porcine eyes. Functional properties of Kir channels were characterized using, whole cell patch clamp recording techniques To confirm the unique Kir7.1 electrophysiological properties, permeability (P^<RB>/P^K) and inward slope conductance (g^<Rb>/g^k sequence for monovalent K^+ and Rb^+ were determined. Expression of Kir7.1 mRNA in both cells was detected by reverse
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transcription-polymerase chain reaction (RT-PCR). Whole cell current in the IPE exhibited a mild inward K^+ rectification, and showed little dependence on [K^+]_o. Unusual high (7.04 ± 1.7) Rb^+ t K^+ inward conductance ratio indicated that Kir7.1 subunit was expressed in the IPE as the same as RPE cells. Also, Kir7.1 mRNA was detected in both porcine IPE and RPE by RT-PCR. However, functional expression of Kir conductance in IPE cells (21.7 S/F) was much smaller than that in RPE cells (205.6 S/F). Kir7.1 subunit was predominantly expressed In the acutely dissociated porcine IPE and its functional properties are similar to those in the RPE, however the current density seems too small to fulfill the task of the Kir function of RPE. These results suggested that IPE may have some similar functions of the RPE, and thus supported the idea that IPE cells could be transplanted into the subretinal space to substitute for RPE cells. However before putting the IPE transplantation to practical use, i.e., the treatment for retinal degenerative diseases such as age-related macular degeneration, the amplification of Kir function in the IPE should be considered. Less
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