Growth factors in combination, but not individually, rescue rd mouse photoreceptors in organ culture

The rd mouse retina is an animal model for human retinal dystrophy in which the rod photoreceptors undergo apoptosis during the first 4 weeks in vivo or in organ culture. We have examined the effect of different families of trophic factors on the survival of rd mouse photoreceptors in organ culture. Retinas were harvested from rd mice at postnatal day 2 and grown in organ culture for 27 days in vitro (DIV) in DMEM with 10% fetal calf serum. Ciliary neurotrophic factor (CNTF), brain-derived neurotrophic factor (BDNF), fibroblast growth factor-2 (FGF2), glial cell line-derived neurotrophic factor (GDNF), neurturin, and persephon were added individually or in combination to the medium at a dose of 50 ng/ml or less. CNTF + BDNF in combination resulted in photoreceptor survival comparable to wild-type retinas after 27 DIV. CNTF + FGF2 or CNTF + GDNF produced a partial prevention of photoreceptor death. Photoreceptor degeneration was not blocked by any of the trophic factors added individually. A significant increase in photoreceptor survival was seen with forskolin added to CNTF, but not to BDNF, FGF2, or GDNF, These results demonstrate that trophic factors promote photoreceptor survival through a synergistic interaction. Increased understanding of receptor interactions and signaling pathways may lead to a potential therapeutic role for combinatorial trophic factors in treatment of photoreceptor dystrophies. (C) 2000 Academic Press.