L-DEPRENYL PROTECTS INJURED RETINAL PRECURSOR CELLS IN-VITRO

We evaluated the ability of L-deprenyl, a monoamine oxidase-B inhibito r (MAO-B), to preserve the viability of serum-deprived immortalized re tinal precursor cells in vitro. We serum-deprived rat neural retinal g anglion cells immortalized by an incompetent retro virus. We instilled L-deprenyl in concentrations ranging from 0.01 to 100 mu M. After 72 hours we performed a cell count of the L-deprenyl cultures and the con trol (no L-deprenyl instilled) with a hemocytometer and flow cytometry . We used transmission electron microscopy, DNA gel electrophoresis, a nd flow cytometry to determine the mechanism of cell death. This study showed that all five concentrations of L-deprenyl statistically incre ased the survival rate of immortalized retinal precursor cells at 72 h ours in the serum-deprived medium (P = 0.01, ANOVA test). Ten mu M and higher appeared to provide the greatest immortalized retinal precurso r cell survival (12.7 x 10(-4) cells) compared to the control (5.8 x 1 0(-4) cells). Flow cytometry also demonstrated a higher percentage of surviving cells at 10 mu M (80%) and 100 mu M (76%) than with the cont rol (58%) (P = 0.0017, chi(2) test). Transmission electron microscopy, DNA electrophoresis, and flow cytometry showed that the mode of cell death was by apoptosis. This study suggests that L-deprenyl may be wor thy of further investigation as a neuroprotective agent to treat chron ic open-angle glaucoma.