MINIREVIEW
Hypoxia-Induced Pulmonary Vascular Remodeling: Contribution of the
Adventitial Fibroblasts
K. R. Stenmark1, D. Bouchey1, R. Nemenoff2,
E. C. Dempsey3,
M. Das1
1Cardiovascular Pulmonary, Developmental Biology Research Laboratories,
Denver,
2Division of Renal Medicine, University of Colorado Health Sciences
Center, Denver,
3Denver Veterans Administration Medical Center, Denver, USA
Received February 29, 2000
Accepted April 3, 2000
Summary
Vascular repair in response to injury or stress (often
referred to as remodeling) is a common complication of many cardiovascular
abnormalities including pulmonary hypertension, systemic hypertension,
atherosclerosis, vein graft remodeling and restenosis following balloon
dilatation of the coronary artery. It is not surprising that repair and
remodeling occurs frequently in the vasculature in that exposure of blood
vessels to either excessive hemodynamic stress (e.g. hypertension), noxious
blood borne agents (e.g. atherogenic lipids), locally released cytokines, or
unusual environmental conditions (e.g. hypoxia), requires readily available
mechanisms to counteract these adverse stimuli and to preserve structure and
function of the vessel wall. The responses, which were presumably evolutionarily
developed to repair an injured tissue, often escape self-limiting control and
can result, in the case of blood vessels, in lumen narrowing and obstruction to
blood flow. Each cell type (i. e. endothelial cells, smooth muscle cells, and
fibroblasts) in the vascular wall plays a specific role in the response to
injury. However, while the roles of the endothelial cells and smooth muscle
cells (SMC) in vascular remodeling have been extensively studied, relatively
little attention has been given to the adventitial fibroblasts. Perhaps this is
because the fibroblast is a relatively ill-defined cell which, at least compared
to the SMC, exhibits few specific cellular markers. Importantly though, it has
been well demonstrated that fibroblasts possess the capacity to express several
functions such as migration, rapid proliferation, synthesis of connective tissue
components, contraction and cytokine production in response to activation or
stimulation. The myriad of responses exhibited by the fibroblasts, especially in
response to stimulation, suggest that these cells could play a pivotal role in
the repair of injury. This fact has been well documented in the setting of wound
healing where a hypoxic environment has been demonstrated to be critical in the
cellular responses. As such it is not surprising that fibroblasts may play an
important role in the vascular response to hypoxia and/or injury. This paper is
intended to provide a brief review of the changes that occur in the adventitial
fibroblasts in response to vascular stress (especially hypoxia) and the role the
activated fibroblasts might play in hypoxia-mediated pulmonary vascular disease.
Key words
Vascular remodeling ● Smooth muscle cells ● Hypoxia ●
Mitogen-activated protein kinase ● Protein kinase C ● Extracellular
matrix ● Growth factors ● Tyrosine kinase ● Pulmonary
hypertension
Reprint requests
Kurt R. Stenmark, MD, Professor of Pediatrics, University of
Colorado Health Sciences Center, 4200 E. Ninth Avenue, Box B131, Denver, CO
80262, USA, Fax (303) 315-8353, E-mail: Kurt.Stenmark@UCHSC.edu
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