Expression of Pigment Epithelium–Derived Factor in
Experimental Choroidal Neovascularization
Reem Z. Renno, Ayman I. Youssri, Norman Michaud, Evangelos S. Gragoudas, and
Joan W. Miller
PURPOSE. To investigate the expression of pigment epithelium–
derived factor (PEDF) in the rat laser-injury model of choroidal
METHODS. Retinas were immunostained for PEDF at different
times (1, 2, and 3 weeks) after laser injury. Levels of PEDF
protein in the vitreous at 1, 3, 7, 14, and 28 days after laser
injury were also assayed by Western blot.
RESULTS. Protein levels of PEDF in the vitreous were increased
during the first 7 days after CNV induction. Immunostaining for
PEDF was observed throughout normal nonlasered control
retinas, sham-lasered retinas, and areas remote to laser lesions,
which were generally more intense in the outer nuclear layer
(ONL) and less intense in the internal nuclear layer (INL).
Decreased expression of PEDF was observed in flanking areas
adjacent to the injury site and was confined mainly to the ONL.
In the injury sites, immunostaining within the ONL was either
absent or decreased for up to 3 weeks after laser injury (the
duration of the study). Preadsorption of the anti-PEDF antibody
with the immunizing peptide blocked specific labeling in the
CONCLUSIONS. These results demonstrate an inverse correlation
of expression of PEDF and formation of CNV in the experimen-
tal model and suggest that decreased expression of PEDF plays
a permissive role in the formation of CNV. PEDF analogues may
be a reasonable treatment strategy for CNV. (Invest Ophthal-
mol Vis Sci. 2002;43:1574–1580)
Western countries.1–3Dry AMD is the more common form of
the disease, characterized by drusen and pigmentary and atro-
phic changes in the macula, with slowly progressive loss of
central vision. Wet or neovascular AMD is characterized by
subretinal hemorrhage, fibrosis, and fluid secondary to choroi-
dal neovascularization (CNV), with more rapid and pro-
nounced loss of central vision.4Although less common than
dry AMD, neovascular AMD accounts for 80% of the severe
vision loss due to AMD.5,6Current treatments for CNV are
designed to destroy or remove the abnormal blood vessels and
do not address the underlying stimuli responsible for neovas-
cularization.7,8Development of pharmacologic therapy for
ge-related macular degeneration (AMD) is the leading
cause of severe vision loss in people aged 65 and older in
CNV would be a major advance. One strategy could include the
development of analogues to endogenous inhibitors of angio-
Angiogenesis is controlled by the local balance between
factors that either stimulate or inhibit vessel growth. In most
normal tissues, inhibitory influences predominate, and vessels
remain quiescent.9,10In contrast, in a variety of pathologic
states, such as tumor growth and neovascular AMD, neovascu-
larization occurs because of decreased production of inhibitors
and/or increased production of angiogenic stimulators.11,12
Although efforts have focused so far on identifying new
angiogenic stimulators and investigating the role of these fac-
tors in ocular neovascularization,13little attention has been
given to the identification of angiogenic inhibitor factors in-
volved in ocular neovascularization.
Pigment epithelium–derived factor (PEDF) is a member of
the serine protease superfamily secreted by the RPE cells in the
developing and adult retina.14It localizes to the interphotore-
ceptor matrix (IPM), the functional complex wherein the RPE
interacts with the photoreceptors. PEDF is present in bovine
IPM as a soluble extracellular monomeric glycoprotein that by
itself confers neurotrophic activity to the IPM.15In vitro, it
induces neuronal differentiation and promotes survival of the
cerebellar granule neurons.14Gene expression of PEDF was
found in human ciliary epithelium, and PEDF protein was
found in the aqueous humor.16Furthermore, proteolytic activ-
ity directed toward PEDF was found in vitreous of bovine eyes,
indicating that the vitreous has a serine-proteolytic activity that
cleaves PEDF and may play a role in modulating PEDF in vivo.
Expression of PEDF appears to be growth-state dependent:
senescent cells do not express PEDF in vitro.17In addition, the
PEDF gene is closely linked to an autosomal dominant locus for
retinitis pigmentosa,18suggesting that PEDF could be a survival
factor for photoreceptors. A role for PEDF has also been sug-
gested in central areolar choroidal dystrophy (CACD),19auto-
somal dominant progressive cone dystrophy (CORDS),20and
Leber congenital amaurosis.21Intravitreal injections of PEDF
delay the death of photoreceptors in mouse models of inher-
ited retinal degeneration14and the RCS rat. Moreover, the
vitreous humor is generally antiangiogenic and devoid of ves-
sels, and it also normally contains a high concentration of
PEDF.22PEDF has been shown recently to be a potent inhibitor
of ischemia-driven retinal neovascularization.23,24
Disruption of the Bruch membrane in the rat by laser treat-
ment results in formation of CNV.25This effect is usually
attributed to changes in the level of angiogenic growth factors
such as vascular endothelial growth factor (VEGF), which is
upregulated during formation of CNV.26,27Capillaries originate
within the choroid and extend through the disrupted Bruch
membrane into the outer nuclear layer (ONL). Multiple layers
of pigment-laden cells are found interspersed with choroidal
capillaries within the neovascular membrane. Angiographic
fluorescein leakage is observed in approximately half of laser-
injury sites. Fluorescein leakage peaks within 2 to 3 weeks after
induction and shows regression thereafter, although CNV may
still be observed histologically.25The purpose of this study was
From the Angiogenesis Laboratory, Retina Research Institute, Mas-
sachusetts Eye and Ear Infirmary, Harvard Medical School, Boston,
Supported by the Massachusetts Lions Eye Research Fund and the
S. Elizabeth O’Brien Trust.
Submitted for publication March 23, 2001; revised December 26,
2001; accepted January 14, 2002.
Commercial relationships policy: N.
The publication costs of this article were defrayed in part by page
charge payment. This article must therefore be marked “advertise-
ment” in accordance with 18 U.S.C. §1734 solely to indicate this fact.
Corresponding author: Joan W. Miller, Angiogenesis Laboratory,
Retina Research Institute, Massachusetts Eye and Ear Infirmary, 243
Charles Street, Boston, MA 02114; jwmiller.@meei.harvard.edu.
Investigative Ophthalmology & Visual Science, May 2002, Vol. 43, No. 5
Copyright © Association for Research in Vision and Ophthalmology
to determine the expression of PEDF during the course of
CNV’s development in the rat model of laser-induced CNV.
MATERIALS AND METHODS
Experimental CNV Model
The laser-injury rat model of CNV was modified from earlier re-
ports.25,28Forty adult male pigmented brown Norway rats (Jackson
Laboratories, Bar Harbor, ME) were used in the study. The study design
is summarized in Table 1. All procedures were conducted in accor-
dance with the ARVO Statement for the Use of Animals in Ophthalmic
and Vision Research, and the guidelines of the Massachusetts Eye and
Ear Infirmary’s Animal Care Committee. The rats were anesthetized
with an intraperitoneal injection of 0.2 mL of a 50:50 mixture of
ketamine hydrochloride (20 mg/mL; Bayer Corp., Kansas City, MO)
and xylazine hydrochloride (100 mg/mL; Abbott Laboratories, Abbott
Park, IL). Animals were killed with an overdose of the same anesthetic
mixture, followed by neck dislocation.
The pupils were dilated with 1% tropicamide, and four to six
photocoagulation lesions, using an argon laser (100-um spot size,
0.1-second duration, 120–160 mW; model 920; Coherent, Palo Alto,
CA) were delivered between the retinal vessels in a peripapillary
distribution in each fundus, using a slit lamp delivery system and a
cover glass as a contact lens. Production of a bubble at the time of laser
treatment confirmed the rupture of the Bruch membrane. Baseline
fundus photographs were taken before laser treatment, and fluorescein
angiograms were performed in each animal on the assigned date of
death, with a fundus camera (TRC-50VT; Topcon, Paramus, NJ) with
images captured on computer (Imagenet for Windows; Topcon) after
an injection of 1 mL 1:10 diluted 10% fluorescein sodium (Alcon, Fort
Worth, TX). Sham laser treatment involved the placement of three to
four laser burns of 1000 ?m at 120 to 160 mW, yielding an irradiance
1000 times less than the actual laser-injury lesions. No breaks in the
bubble formation in the Bruch membrane or hemorrhages were noted
in the sham-lasered eyes.
Protein Electrophoresis and Western
The eyes were enucleated at 1, 3, 7, 14, 21, and 28 days after laser
photocoagulation (four rats at each time point). Control animals were
four nonlasered rats. To remove the vitreous, eyes were bisected
posterior to the iris, the lens was lifted out, and the vitreous removed
and placed in tubes (Eppendorf; Brinkman Instruments, Westbury, NY)
on ice after careful examination and dissection to remove any contam-
inating material. Rat vitreous from both eyes was pooled, and volume
was measured by pipette aspiration. Next, vitreous was quickly ho-
mogenized with ice-cold lysis buffer (pH 7.5) containing 10 mM Tris,
130 mM NaCl, 1% Triton X-100, 10 mM NaF, 10 mM NaPi, 10 mM
NaPPi, 16 ?g/mL benzamidine, 10 ?g/mL phenanthrolene, 10 ?g/mL
aprotinin, 10 ?g/mL leupeptin, 10 ?g/mL pepstatin, and 4 mM 4-(2-
aminoethyl)-benzenesulfonyl fluoride (AEBSF). An aliquot was re-
moved for protein quantitation using a bicinchoninic acid (BCA) pro-
tein assay (Pierce, Rockford, IL), and the rest of the supernatant was
stored at ?70°C for future analysis of PEDF levels.
Electrophoresis of proteins was performed with 12% SDS-polyacryl-
amide gels. All samples were boiled in denaturing sample buffer, and
equal amounts of proteins were loaded on each lane. Proteins were
separated at room temperature under reducing conditions at 120 V for
1 hour. Western blot transfer of separated proteins was performed at
room temperature, using polyvinylidene difluoride membranes at 50
mA for 1 hour. To verify equal protein loading, blots were stained with
0.1% ponceau red (Sigma, St. Louis, MO) diluted in 5% acetic acid.
Afterward, blots were blocked for 1 hour in TBS (10 mM Tris-HCl [pH
7.5], 150 mM NaCl) containing 5% nonfat dried milk. Next, the mem-
branes were probed with a 1:250 dilution of primary antibody in TBS
containing 2.5% nonfat dried milk for 1.5 hours. Rabbit polyclonal
antibody against PEDF (anti-EPC-1) was a generous donation of Vin-
cent J. Cristafalo and Mary K. Francis (Lankenau Medical Research
Center, Wynnewood, PA). After incubation with primary antibody, the
blots were washed for 30 minutes with frequent changes of TBS and
blocked in 1% nonfat dried milk in TBS for 30 minutes, followed by
incubation in a peroxidase-coupled secondary antibody for 1 hour in
TBS containing 1% nonfat dried milk. The blots were washed for 1 hour
with frequent changes of TBST (TBS with 0.1% Tween). Immunoblot
analysis was performed using enhanced chemiluminescence with
Western blot detection reagents (Amersham, Piscataway, NJ) followed
by exposure to autoradiograph film (ML; Eastman Kodak, Rochester,
NY). Blots were analyzed by densitometry on computer (ImageQuant
software; Molecular Dynamics, Inc., Sunnyvale, CA). Amount of PEDF
expressed in arbitrary units (AU) was normalized to the total amount of
protein per sample. Data were plotted as AU PEDF per microliter
vitreous versus time point.
Late fluorescein angiogram showing hyperfluorescence and leakage of
fluorescein in the photocoagulated lesions, demonstrating the forma-
tion of choroidal neovascularization.
Sample fluorescein angiogram 3 weeks after laser injury.
TABLE 1. Summary of Animals (n ? 40)
Time Point at
1 day post-injury
3 days post-injury
7 days post-injury
14 days post-injury
21 days post-injury
28 days post-injury
1 week post-injury
2 weeks post-injury
1 week post-injury
2 weeks post-injury
3 weeks post-injury
Time after laser-induced injury.
IOVS, May 2002, Vol. 43, No. 5
PEDF in Choroidal Neovascularization 1575
Twelve animals were killed after fluorescein angiography at 1 to 3
weeks after CNV induction. The control consisted of nonlasered eyes
and sham-lasered eyes at 1 and 2 weeks. Four eyes were processed for
each time interval. Eyes were enucleated, and the lens and anterior
segment were removed. Remaining eyecups were fixed in formalin for
1 hour at room temperature and processed for paraffin-embedded
sections. All sections were mounted on coated slides (Superfrost Plus;
Fisher Scientific, Fairlawn, NJ). Serial sections were cut at 8-?m thick-
ness. Before immunohistochemistry, some sections were stained with
hematoxylin and eosin (H&E) and observed using a light microscope to
help localize the CNV.
Immunohistochemical staining with rabbit polyclonal anti-PEDF raised
to 327 to 343 amino acid residues (generous donation of Noel Bouck,
Northwestern University, Chicago, IL) was performed using the anti-
gen-retrieval method. All incubations were performed in a moist cham-
ber at room temperature. Briefly, sections were deparaffinized and
then placed in antigen-retrieval solution (Dako, Carpinteria, CA) for 20
minutes at 95°, after which sections were blocked with 5% fetal bovine
serum (FBS) in 0.1 M PBS (pH 7.4) for 1 hour. The sections were
incubated with anti-PEDF (1:50 dilution in 1% FBS-PBS) overnight at
room temperature. The slides were washed in PBS for 10 minutes,
followed by incubation in a biotinylated-coupled secondary antibody
(Jackson ImmunoResearch, West Grove, PA) for 1 hour in PBS con-
taining 1% FBS. The slides were washed in PBS for 10 minutes and then
visualized with the avidin-biotin complex (ABC) method (Vectastain
Elite; Vector Laboratories, Burlingame, CA). Slides were incubated with
diaminobenzidine to give a brown reaction product and were lightly
counterstained with Mayer hematoxylin before mounting. Photo-
graphs were then obtained (Eclipse E600; Nikon, Melville, NY, and a
Spot charge-coupled device [CCD] camera; Diagnostic Instruments,
Sterling Heights, MI). Normal nonlasered and sham-lasered retinas
were used as the positive control. Control sections were treated in the
same way with omission of primary antibody or preincubation of the
primary antibody overnight at 4°C with PEDF protein at a concentra-
tion of 100 ?g/mL.
The degree and pattern of immunostaining, both within and be-
tween specimens, was assessed by a masked histologist, using standard
light microscopy. The intensity of labeling was graded qualitatively as
grade 1, slightly stained; grade 2, moderately stained; grade 3, strongly
stained; and grade 4, maximum staining as in the nonlasered control.
To compare the immunostaining levels in a quantitative fashion, sec-
tions were imaged with a digital camera using identical microscope
settings. Labeling in the ONL was then quantified by computer (Image;
Scion Corp., Frederick, MD).
Data were analyzed using a one-way analysis of variance (ANOVA).
Statistical significance was set at P ? 0.05.
PEDF Levels in Vitreous during the Course of
To investigate changes in the vitreous levels of PEDF protein
during the course of CNV’s development, CNV lesions were
induced in rats, as previously described. Four animals were
used per time point (Fig. 1). At days 1, 3, 7, 14, 21, and 28 after
induction, animals were killed, and vitreous was assayed for
PEDF levels by Western blot analysis. Control experiments
were performed with vitreous of eyes that had not been la-
sered. Densitometric analysis of Western blot was normalized
to the volume loaded. Figure 2 represents the average of
is plotted (n ? 4, ? SD). Results show an increase in PEDF vitreous level during the first 7 days after CNV induction (P ? 0.05).
Quantitative densitometric analysis of PEDF vitreous levels after CNV induction over time. The average density per microliter vitreous
TABLE 2. Grading of PEDF Immunostaining in Rat CNV
Grade 1Grade 2 Grade 3Grade 4
CNV (n ? 11)
(n ? 11)
CNV (n ? 8)
Sham (n ? 2)
(n ? 2)
Data are percentage of total group achieving each grade.
1576Renno et al.
IOVS, May 2002, Vol. 43, No. 5
relative densities of vitreous PEDF over the time course of
development of CNV. There seemed to be an increase in PEDF
vitreous protein levels during the first week after induction of
CNV. However, no difference was recorded afterward, and
levels were comparable with control levels at week 1 and up to
at least 28 days after CNV.
PEDF Immunostaining in Laser-Induced CNV
Immunohistochemical expression of PEDF during the course
of CNV was examined. Immunostaining was analyzed in 11
CNV lesions in 7 of 11 rats with laser injury at week 1 (two
animals, two lesions), week 2 (three animals, seven lesions)
and week 3 (two animals, two lesions). Control eyes were
those of normal nonlasered rats and sham-lasered ones. All
immunostaining was accompanied by appropriate control
staining, and none of the negative control samples generated
detectable immunostaining. The generation of laser burns re-
quired the use of pigmented animals. As a result of the density
of melanin pigmentation, it was difficult to detect immunopos-
itivity in cells in the choroid and RPE layer. Results of the
immunohistochemical analysis by a masked histologist are sum-
marized in Tables 2 and 3. In addition, analysis of immunostain-
ing by computer (Image; Scion) allowed quantitative analysis of
intensity of staining and confirmation of findings (Fig. 3).
Nonlasered Control Eyes. Immunolabeling for PEDF was
observed throughout normal nonlasered control retinas of
brown Norway rats. Intense immunostaining was observed in
the ONL and moderate immunoreactivity in the INL. PEDF
immunoreactivity in nonlasered eyes was most intense and was
scored as grade 4.
Sham-Lasered Eyes. PEDF immunoreactivity in sham-la-
sered retinas was found to be diminished compared with that
in nonlasered retinas. Immunolabeling in sham eyes was typi-
cally grade 3.
Laser-Treated Eyes. Marked focal downregulation of
PEDF’s expression (weak immunoreactivity) was observed
throughout the CNV regions (Fig. 4C, 4D) and adjacent flank-
ing areas (Fig. 4B) at 1, 2, and 3 weeks after laser injury.
Immunoreactivity in the area of CNV was judged to be pre-
dominantly grade 1 (81.8% grade 1 and 18.25% grade 2),
whereas that of flanking regions was predominantly grade 2
(27.3% grade 1 and 72.7% grade 2). Downregulation of PEDF
signal persisted through the 3 weeks of follow-up.
In the nonlasered regions, including areas remote to the
laser injury (Fig. 4A), there was little variation in the immuno-
labeling pattern for PEDF at the times after laser treatment,
compared with sham-lasered retinas (Fig. 4E). Areas remote to
CNV were found to be predominantly grade 3 (12.5% grade 2,
62.5% grade 3, and 25% grade 4) and sham-lasered retinas were
all grade 3.
The intensity of PEDF staining using image software in
sham-lasered, normal, areas remote to the CNV was almost two
times that overlaying CNV and flanking areas (Fig. 3).
PEDF Immunostaining in CNV at 1, 2, and 3 Weeks
after Laser Injury. PEDF immunostaining in CNV at 1 and 2
weeks after laser injury was mostly grade 1, whereas in CNV 3
average pixel intensity is plotted ? SD.
Quantitative analysis of PEDF immunostaining intensity in the ONL after experimental choroidal neovascularization induction. The
TABLE 3. Grading of PEDF in 1-, 2-, and 3-Week-Old CNV
1 Week (n ? 2)
2 Weeks (n ? 7)
Grade 1 (100%)
Grade 1 (85.7%)
Grade 2 (14.3%)
Grade 2 (100%)
Grade 2 (100%)
Grade 1 (42.9%)
Grade 2 (57.1%)
Grade 2 (100%)
Grade 3 (100%)
Grade 1 (20%)
Grade 2 (80%)
Grade 4 (100%)3 Weeks (n ? 2)
Data are immunostaing grades, with percentages of total group at 2 weeks in parentheses.
IOVS, May 2002, Vol. 43, No. 5
PEDF in Choroidal Neovascularization1577
weeks after laser treatment, injury was grade 2. Staining in
flanking areas at 1 and 3 weeks after laser injury was grade 2
and was distributed almost equally between grade 1 and grade
2 at 2 weeks. Staining in areas remote to the CNV was mostly
grade 3 at 1 week, grade 2 at 2 weeks, and grade 4 at 3 weeks
after laser injury (Table 3, Fig. 5).
The purpose of this study was to investigate changes in ex-
pression of the antiangiogenic factor PEDF in the retina after
laser injury over the course of CNV’s development and to try to
correlate these findings with intravitreal levels of PEDF. First,
our results demonstrate that PEDF immunostaining in the nor-
mal rat retinal layers localized mainly to the ONL—the most
avascular layer of the retina—and, to a lesser extent, to the INL.
The rat vitreous was found to contain abundant amounts of
PEDF proteins. This confirms the findings of others15,23who
have studied murine and bovine retinas and vitreous.
We also found that there was a significant increase in vitre-
ous protein levels of PEDF during the first 7 days after CNV
induction; however, PEDF levels returned to baseline control
levels thereafter. The increase of PEDF in the vitreous after
laser injury may be the result of PEDF’s release from damaged
retinal cells, in particular from the RPE cells that produce it and
the IPM where it localizes. These findings must be interpreted
with caution, because changes in the level of an abundant
protein may be difficult to detect after focal injury.
PEDF protein expression over laser-
induced CNV in adult rat. Retinas
were harvested at 1, 2, and 3 weeks
after induction from brown Norway
rats and stained for PEDF. Note accu-
mulation of PEDF (E, arrow), stained
reddish brown. Control sections di-
rectly adjacent to lesion (B), remote
to lesion (A) or sham (E) stained with
primary antibody, (F) with pread-
sorbed primary antibody, or (G)
downregulation of PEDF (D; arrow-
head) in the area of CNV (C, D; ar-
row). Retina layers indicated in (B)
include retinal pigment epithelium
(RPE), outer nuclear layer (ONL), in-
ner nuclear layer (INL), and ganglion
cell layer (GCL). Rat eyes were fixed
in formalin within 1 to 5 minutes of
harvest. For immunostaining, paraf-
fin-embedded sections were incu-
bated with anti-PEDF and visualized
with the avidin biotin complex
method. Scale bar, 50 ?m.
Focal downregulation of
1578 Renno et al.
IOVS, May 2002, Vol. 43, No. 5
In the laser-injury model of CNV, expression of PEDF during
CNV’s development followed a pattern that might be expected
of an angiogenic inhibitor, in that the amount of inhibitory
PEDF was downregulated in the areas of laser injury and CNV’s
formation, suggesting that its loss plays a permissive role in
formation of CNV. It is worth noting that mild laser injury
(sham laser) alone without subsequent development of CNV
appeared to result in mild focal downregulation of PEDF’s
signal compared with nonlasered retinas, but to a much lesser
extent than the downregulation witnessed in the areas that
sustained significant injury and in which CNV developed.
Moreover, during the laser induction of CNV, some RPE cells
are invariably injured, and this may contribute to the decreased
immunostaining for RPE-produced PEDF. However, the num-
ber of RPE cells that were damaged was small, and flanking
areas with undamaged RPE also showed decreased expression
of PEDF. In addition, RPE-produced VEGF has been shown to
be increased after laser-induced CNV.
The most pronounced downregulation of PEDF’s expres-
sion occurred in 2-week-old CNV lesions, which corresponds
to the peak temporal incidence of angiographically leaking
CNV, as described by other groups.25,28The PEDF downregu-
lation pattern during CNV’s development seems to parallel
somewhat the upregulation of expression of VEGF,29the latter
being strongest at 1 week after photocoagulation in lasered
lesions and decreased by 4 weeks.
The mechanism of PEDF’s action is still being elucidated.
However, a recent report by Stellmach et al.24shows that PEDF
causes apoptosis in activated endothelial cells, and this may be
the mechanism of inhibition of angiogenesis. They found that
PEDF induces apoptosis in cultured endothelial cells and leads
to an eightfold increase in the number of apoptotic endothelial
cells as detected in situ, when the ischemic retinas of PEDF-
treated animals were compared with vehicle-treated control
retinas. Recent evidence points to the possible existence of a
PEDF receptor.30Purification, isolation, and characterization of
such receptors may help unravel the mechanism of action and
regulation of PEDF. PEDF agonists that bind PEDF receptors
may be a reasonable therapeutic approach to CNV. Because
PEDF synthesis and secretion are diminished in senescent
cells,17it can be speculated that senescent RPE in AMD may
produce less PEDF and thereby facilitate the development of
CNV. The Tie family of receptors and their ligands the angio-
poietins (Ang) also appear to be involved in the control of
vascular proliferation or regression. A recent report by Hangai
et al.31demonstrated that Ang1 and Ang2 colocalize with VEGF
in CNV stromal cells and that VEGF induces the upregulation of
Ang1’s expression in cultured RPE cells. A study of the tempo-
ral expression of angiopoietins during the course of develop-
ment of CNV would be of great interest and help elucidate the
interrelationship of PEDF, VEGF, and angiopoietins.
In summary, expression of PEDF has been shown to be
decreased at sites of laser injury and development of CNV,
suggesting that its release or activation may be part of that
development. Because focal downregulation of PEDF may play
a role in the pathogenesis of CNV, these results suggest that
PEDF analogues may be a useful treatment for CNV in AMD and
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