Atherosclerosis 152 2000 35 – 42
Different radiosensitivity of smooth muscle cells and endothelial cells in vitro as demonstrated by irradiation from a Re-188 filled
balloon catheter
Jo¨rg Kotzerke
a,
, Ralf Gertler
b
, Inga Buchmann
a
, Regine Baur
b
, Vinzenz Hombach
b
, Sven Norbert Reske
a
, Rainer Voisard
b
a
Department of Nuclear Medicine, Uni6ersity of Ulm, D-
89070
Ulm, Germany
b
Department of Internal Medicine II Cardiology
, Uni6ersity of Ulm, D-
89070
Ulm, Germany Received 12 May 1999; received in revised form 4 October 1999; accepted 29 October 1999
Abstract
There is an increasing interest in irradiation to control restenosis after balloon angioplasty by an internal radioactive source. Differences in radiosensitivity of the predominant cells of the human coronary artery i.e. endothelial cells HCAEC, smooth
muscle cells from the media HCMSMC and from plaque material HCPSMC, are issues of controversal discussion. Therefore, we investigated the graded inhibition of cells by irradiation from a balloon catheter filled with a high-energy beta-emitter
Rhenium-188 in vitro. HCPSMC, HCMSMC and HCAEC were cultured and irradiated with increasing dose from 7.5 to 37.5 Gy at a dose rate of 1.5 9 0.3 Gymin. After irradiation, bromodeoxyuridine BrdU was added and cells were fixed 18 h later.
In a limited field opposite to the balloon, the number of BrdU-positive cells were analysed in comparison to non-irradiated controls. Significant inhibition was demonstrated in HCPSMC and HCMSMC at 7.5 Gy while HCAEC needed 22.5 Gy for
similar effects. The antiproliferative effect was dose dependent in all cell strains. The effect of irradiation with 22.5 Gy on smooth muscle a-actin, vimentin, and a-tubulin of HCPSMC and HCMSMC and on von Willebrand factor vWF, vimentin, and
a-tubulin of HCAEC was investigated by means of indirect immunofluorescence. Within 18 h after irradiation no effect on cytoskeletal components and vWF was documented. This in vitro study demonstrates that irradiation inhibits HCMSMC and
HCPSMC at lower dose rates compared to HCAEC. © 2000 Elsevier Science Ireland Ltd. All rights reserved.
Keywords
:
Re-188; Irradiation; Smooth muscle cell; Balloon catheter; Proliferation www.elsevier.comlocateatherosclerosis
1. Introduction
Restenosis is the major drawback of percutaneous transluminal coronary angioplasty PTCA and occurs
within 6 months in 40 – 60 [1]. Various mechanisms for restenosis have been proposed: migration of my-
ocytes from the media to the intima, forming the neointima [2]; damage of the adventitia resulting in
proliferation of adventitial fibroblasts and migration of these mesenchymal cells to the media and neointima [3];
organization of a mural thrombus, resulting in a local hypertrophic scar [4]; release of cytokines and growth
factors, e.g. by monocytesmacrophages which mediate the cellular migration and proliferation [5,6]. It was
demonstrated in vitro [7 – 9], in animal studies [10 – 12] and more recently in early clinical studies, that irradia-
tion can prevent coronary artery restenosis at least in part by b- or g-emitting wires [13 – 16]. A new concept
is the use of a liquid-filled balloon containing a beta- emitting radioisotope which combines the advantages
of optimal energy transfer to the vessel wall and radia- tion protection of the environment [17]. Rhenium-188
Re-188 is a high-energy b-emitter that is routinely available from a W-188Re-188 generator in liquid
form and that is therefore an ideal b-emitter for this purpose.
The predominant cells of the coronary arteries are the endothelium HCAEC and smooth muscle cells in
Corresponding author. Tel.: + 49-731-5024507; fax: + 49-731- 5024512.
E-mail address
:
joerg.kotzerkemedizin.uni-ulm.de J. Kotzerke. 0021-915000 - see front matter © 2000 Elsevier Science Ireland Ltd. All rights reserved.
PII: S 0 0 2 1 - 9 1 5 0 9 9 0 0 4 4 5 - 1
the media HCMSMC. A different entity is the smooth muscle cell in plaque material HCPSMC. Some inves-
tigators who have compared the sensitivity of endothe- lial cells with other cell types constituting the vessel wall
have concluded that the endothelial cells are the most radiosensitive [7,18]. However, other studies could not
demonstrate major differences in survival following ir- radiation [19]. In addition, the experience is limited and
restricted to a few tissues, and differences are known from animal and human cells as well as in different
individuals [18]. Moreover, data about the radiosensi- tivity of smooth muscle cells isolated from human
plaque tissue are very limited [20,21].
Different investigations have been published on the determination of endothelial cell survival in vitro in-
cluding different end-points e.g. fraction of growth control, endothelial colonies, apoptotic bodies or cy-
toskeletal alterations. A prescreening system for poten- tial antiproliferative agents was established by Voisard
et al. [22 – 24] which allows the estimation of the amount of proliferating cells and changes of cytoskele-
tal cell structure within 48 – 120 h after exposition to various drugs.
Therefore, we investigated whether the proliferation of the predominant cells in coronary artery disease
HCAEC, HCMSMC, HCPSMC can be reduced by irradiation from a b-emitter i.e. by liquid Rhenium-188
in a balloon catheter. Furthermore, we wanted to clarify whether this effect is dose dependent and com-
parable or different in the various cell types. To com- pare the antiproliferative effect with cell damage we
investigated cytoskeletal components 18 h after irradia- tion by immunofluorescence microscopy.
2. Material and methods
