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T.G. Deering, P.L. Gehlbach, G. Okoye, K. Callahan, W.W. Hauswirth, P.A. Campochiaro; Retinal Function 10 Months After Intraocular or Periocular Injection of AAV-CBA-PEDF . Invest. Ophthalmol. Vis. Sci. 2003;44(13):3586.
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Purpose: Recombinant adeno-associated viral vectors (AAV) provides sustained expression of proteins in the eye. Long-term effects on retinal function are unknown. Here we assess retinal function as measured by electroretinograms (ERGs) in mice 10 months after intravitreous (IV), subretinal (SR), or periocular (PO) injection of type 2 AAV vector expressing pigment epithelium-derived growth factor (PEDF) or green fluorescent protein (GFP) under the control of a chicken ß actin promoter. Methods: C57BL/6 mice were given IV injection of 1µl containing 2x1010 viral particles (vp) of AAV-PEDF (n=11), SR injection of 1µl containing 2x109 vp (n=10), or PO injection of 5µl containing 6x1010 vp (n=9) in their right eye. The corresponding left eye was similarly injected with AAV-GFP, except that 2x1010 vp were used for PO injections. Uninjected mice (n=12) served as age-matched controls. 10 months following injection, scotopic ERGs were recorded using 11 white light, short-flash, intensities -3.00 to +1.40 log cd-s/m2, presented simultaneously to both eyes. Results: There were no significant differences in a- or b-wave amplitudes between IV, SR, or PO AAV-PEDF-injected eyes and their corresponding AAV-GFP injected fellow eye. There was also no difference in ERG amplitudes between eyes given IV or PO injection of either vector and eyes of age-matched, untreated controls. However, at the highest flash intensity (25 cd-s/m2), there was a significant decrease in mean a-wave amplitude (mV) in eyes that had received SR injection of either vector (AAV-PEDF, -52.6, p=0.0001; AAV-GFP, -57.9, p=0.0002) compared to untreated control eyes (-106.5). The mean b-wave amplitude was depressed across the range of flash intensities (0.0025, 0.25, 25 cd-s/m2) in each eye (AAV-PEDF: 46.8, p= 0.0027; 108.3, p=0.0027; 125.5, p=0.0003) (AAV-GFP: 54.8, p=0.0706; 109.2, p=0.0032; 128.0, p=0.00001) compared to untreated eyes (74.9, 177.4, 246.2). Conclusions: A- and b-wave amplitudes were not significantly reduced in eyes that received AAV-PEDF compared to eyes receiving AAV-GFP by the same route, suggesting against a deleterious effect of the PEDF transgene. IV and PO routes of administration showed no deleterious ERG effects, suggesting they are the safest alternatives for delivering an AAV-vectored secretable agent. However, there was reduced retinal function in eyes that had received SR injection of either vector. Additional studies are needed to determine whether this is due to the SR injection itself, or whether the vectors also contribute.
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