Effects of bevacizumab (Avastin) on retinal cells in organotypic culture.
OBJECTIVE
Repetitive intravitreal injections of bevacizumab are a successful treatment option for exudative age-related macular degeneration (AMD). The aim of this study was to evaluate the toxicity of bevacizumab in the adult mammalian neurosensory retina in culture.


METHODS
Adult porcine neurosensory retinas were cultured adjoined to the retinal pigment epithelium-choroid layer (retina-RPE-choroid complex) in static culture for 3 days, whereas neural retinas alone were cultured in a perfusion chamber for 3 days. Bevacizumab was added to the culture and perfusion medium at three concentrations (0.25 mg/mL [n = 6], 0.5 mg/mL [n = 6], and 1.25 mg/mL [n = 6]). Retina-RPE-choroid complex and neural retinas alone cultured without bevacizumab were used as controls. After 3 days in culture, the neural retinas alone and the retina-RPE-choroid complexes were analyzed histologically and immunohistochemically for the expression of glial fibrillary acidic protein (GFAP), vimentin, glutamine synthetase, rhodopsin, smooth muscle actin (SMA), and apoptosis.


RESULTS
No toxic effects on ganglion or photoreceptor cells were observed at any concentration of bevacizumab. The expression of GFAP and vimentin was slightly increased in Müller cells, whereas glutamine synthetase and rhodopsin were unaffected by bevacizumab. However, significantly enhanced SMA expression in retina blood vessels was observed in retinas cultured in the presence of bevacizumab.


CONCLUSIONS
Bevacizumab was well tolerated by ganglion and photoreceptor cells even at concentrations fivefold higher than those used clinically. The increased expression of SMA is an indication of the loss of functional VEGF modulating smooth muscle cells in mature vessels.
Kaempf
Stefanie
S
Department of Ophthalmology and IZKF BIOMAT, RWTH Aachen University, Aachen, Germany. smueller-kaempf@ukaachen.de
Johnen
Sandra
S
Salz
Anna Katharina
AK
Weinberger
Andreas
A
Walter
Peter
P
Thumann
Gabriele
G
D000199:Actins / Q000378:metabolism; D020533:Angiogenesis Inhibitors / Q000008:administration & dosage / Q000633:toxicity*; D000818:Animals; D000911:Antibodies, Monoclonal / Q000008:administration & dosage / Q000633:toxicity*; D061067:Antibodies, Monoclonal, Humanized; D000068258:Bevacizumab; D004305:Dose-Response Relationship, Drug; D005904:Glial Fibrillary Acidic Protein / Q000378:metabolism; D009131:Muscle, Smooth, Vascular / Q000378:metabolism; D009924:Organ Culture Techniques; D020419:Photoreceptor Cells, Vertebrate / Q000187:drug effects; D012160:Retina / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D012165:Retinal Ganglion Cells / Q000187:drug effects; D012171:Retinal Vessels / Q000378:metabolism; D013552:Swine; D014018:Tissue Distribution; D014746:Vimentin / Q000378:metabolism
D000199:Actins; D020533:Angiogenesis Inhibitors; D000911:Antibodies, Monoclonal; D061067:Antibodies, Monoclonal, Humanized; D005904:Glial Fibrillary Acidic Protein; D014746:Vimentin; D000068258:Bevacizumab