Transcript Slide 1

Use of Photoactivated
Crosslinking Agents for
Vascular Repair and Local
Drug Delivery
Kaia L. Kloster, Ph.D.
Avera Research Institute
PhotoBioMed Corporation
University of South Dakota School of Medicine
4-amino-1,8-naphthalimides
H
O
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R'
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R
O
Photochemistry
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h
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R
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h
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*
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b
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a
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R
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a'
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Light Activation Protocol
 Blue light
laser – 457 nm
 High pressure mercury arc lamp with
filters producing 400-500 nm range
 Argon
(predominantly 450 nm)
 ~240 J/cm2
Not associated with excessive heat
or protein denaturation
Naphthalimide Embodiments
O
O
H 2N
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O
H2N
H
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H
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O
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H
H
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O
NH2
CH2OR'
HO
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OH
HO
COO-
COO-OH
O
O
OH
NHR
OH
OH
CH2OR'
OR
CH2OR'
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OR
O
OH
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NHR
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O
CH2OR'
OH
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OR
COOOH
H
CH
OR'
O2
COO-
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NHR
n
O
O
NHR
n
OR
CH OR'
2
COO-O
OHN
OR
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O
NHR
NHR
OHOH
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H
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O
H
OH
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 Tethers
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O
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O
ON
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HO
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O
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N
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O
 Extenders
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O
NH 2
H
NH2
NH2
NH2
NH
O S O
NH
O S O
 Crosslinkers
OR
NH 2
H
N OO
O
O
COO-
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NH
O S O
NH 2O
O
NH 2
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O
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NH
O O
S O
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NH 2
H
NH2
Photoactivation results in reactive sites (*) that
form covalent bonds between tissue substrates.
Requires blue light and compression.
Tissue Substrate #2
Tissue Substrate #1
Crosslinkers
Extenders
Tissue Substrate #1
Tissue Substrate #1
Tissue Substrate #2
Tissue Substrate #2
Less dependent on light
and compression
Tethers
D
D
D
Photoactivation results in a reactive site (*) that
forms a covalent bond with a tissue substrate.
Requires blue light
Tissue Substrate
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D
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D
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D
D
D
Naphthalimide Technology
PBM
parent
technology
Coronary Artery Disease
 Leading cause of morbidity and mortality in
the industrialized world
 Balloon Angioplasty

Restenosis occurs in 30-50% of cases
 Coronary Stents
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Restenosis reduced to 10-30%
 Drug-Eluting Stents
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Promise of eliminating restenosis
Concerns regarding late adverse effects
Concept of the Endogenous Stent
Crosslink arterial proteins in the dilated state
Repair intimal or medial dissections
Tether anti-restenotic agents
Assumptions
 Ability to penetrate the arterial wall
 Ability to deliver the compounds intraluminally
 Ability to bond atheromatous arterial tissue
 Ability to locally delivery and tether anti-
restenotic agents
Penetration of the Arterial Wall
Immersion of Arterial Segments
Hydrophilic
Lipophilic
Combined
Penetration of the Arterial Wall
Intraluminal Delivery
DISPATCH™ Coronary
Infusion Catheter
SciMed®
Penetration of the Arterial Wall
Flurometric Assay Protocol
 Homogenization of control and experimental
tissue
 Preparation of a standard curve and
unknowns
 Fluorescent plate reader to assess relative
fluorescence
 Extrapolation of the naphthalimide content
present in experimental specimens
Intraluminal Delivery
Residual Compound in the Arterial Wall
Hydrophilic Compound
nmol compound/g tissue
2000
*
1500
Immersion
1000
500
0
IMMERSION
DISPATCH DISPATCH W/O
Method of Compound Delivery
Intraluminal Delivery
nmol compound/g tissue
Residual Compound in the Arterial Wall
400
Lipophilic Form
*
300
Immersion
200
100
0
IMMERSION
DISPATCH
DISPATCH W/O
Method of Compound Delivery
Penetration of the Arterial Wall
Intraluminal Delivery
Hydrophilic
Dispatch delivery
2 sec
10-min washout
Film Exposure
2 sec
Control
20 sec
Tissue Bonding Protocol
Arterial Tissue Bonding
Tensile Bond Strength (g/cm2)
Atheromatous Arterial Tissue Bonding
100
Aqueous 1,8-Naphthalimide Compounds
*
75
50
*
*
#
25
0
PBS/DK
PBS/LT H-NAP/DK L-NAP/LT H-NAP/LT
Treatment
In Vitro Simulation
 Air desiccation model to create atherosclerotic
lesions in rabbit carotid arteries
 Atherosclerotic arteries dissected and mounted in an
isolated arterial perfusion apparatus
 In vitro simulation of balloon angioplasty followed by
napthalimide treatment or various controls
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NAP/LT*; PBS/DK; PBS/LT; NAP/DK
 Perfusion fixation of isolated arteries
 Histological examination and image analyses
Retention of Dilated State
Arterial Cross-Sectional Profiles
Acute Post-Angioplasty
4000
2
Area (microns )
Legend
Media
Plaque
Lumen
3000
2000
1000
0
Dye/Dark
Dye/Light
PBS/Dark
Treatment
PBS/Light
Repair of Intimal Dissections
Local Drug Delivery
drug
reactive tether
Target Tissue
Local Drug Delivery
Target Tissue
Local Drug Delivery
Restored blood
flow will wash out
any untethered
drug molecules
Target Tissue
Tethering of Anti-Restenotic Agents
HO
COOO O
OH
CH2 OR'
O
OR'
O
NHR
COOO O
OH
OH
CH2 OR'
O
OR'
OH
O
NHR
n
COOO O
OH
CH2 OR'
O
OR'
NHR
OH
R = -COCH3
R' = -H or -SO 3-
H
nN
R'' = localizing tail
h
HO
COOO O
OH
CH2 OR'
O
OR'
O
NHR
COOO O
OH
OH
CH2 OR'
O
OR'
O
NHR
n
COOO O
OH
CH2 OR'
O
OR'
O
N
NHR
R''
OH
OH
*
n
O
Intraluminal Delivery of Heparin
Drug delivery to the injured arterial wall post-angioplasty
(arrows indicate heavy heparin loading on the blood surface of the artery)
Summary
 Delivery to the arterial wall
 Tissue bonding
 Retention of luminal gains
 Potential repair of intimal and medial
dissections
 Tethering of anti-restenotic agents
Potential for improved long-term outcomes for
coronary revascularization procedures
Future Directions
 Determine if photoactivation of the
naphthalimides improves retention rates upon
reperfusion
 Develop a multifunctional catheter, ideally
capable of:
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

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Balloon angioplasty
Local delivery
Perfusion
Light activation
 Initiate chronic animal experimentation
Questions
???
Additional Applications
 Ophthalmology
 Dermatology
 Vascular Repair
 Vascular Grafting
 Urology
 Dental
 Veterinary