Therapy and prevention 441 Only transient increase of vascular growth factors and microvascular density after percutaneous myocardial laser Mohamed Salem a , Svein Rotevatn a , Reidar J. Pettersen a , Karel Kuiper a , Thorvald Sætersdal b and Jan Erik Nordrehaug a Objective We tested the hypothesis that percutaneous myocardial laser may stimulate microvascular growth in areas surrounding the laser channels. Methods We conducted a study of 24 domestic pigs, which underwent percutaneous myocardial laser to left ventricular myocardium using holmium:YAG laser. The pigs were sacrificed in groups of four after one day, 3–4 days, one week, three weeks and six weeks. Frozen sections from both normal and treated myocardium were prepared for immunofluorescence microscopy and stained with antibodies against von Willebrand factor, vascular endothelial growth factor (VEGF) and Extra Domain-A cellular fibronectin (ED-AcFN). Microvascular density (MVD) and vascular area (VA) were determined in sections stained with antibodies against von Willebrand factor VIII using a digitised image analysis system. When determined in laser treated areas, channel core remnants were excluded from analysis. Results Within the laser channel remnants and in the tissue closely surrounding these, expression of VEGF and ED-AcFN increased significantly after treatment at one, 3–4, and seven days and decreased to normal at three and six weeks. Expression of ED-AcFN was detected adjacent to endothelial cells of microvessels. The original laser channels were rapidly invaded by granulation tissue. There was no sign of recanalization at any stage during the six weeks. Morphometric analysis showed no increase in MVD and VA in the myocardium surrounding the laser channels. Conclusion An increase of VEGF and ED-AcFN after myocardial laser is transient and is not associated with increase of MVD or VA in myocardium not involving laser channel remnants. Coron Artery Dis 15:441–448  c 2004 Lippincott Williams & Wilkins. Coronary Artery Disease 2004, 15:441–448 Keywords: Experimental, heart, cellular, molecular biology, capillaries, cell communication, coronary disease, cytokines, growth factors, myocardial laser a Department of Heart Disease, Haukeland University Hospital, Bergen and b Department of Anatomy and Cell Biology, Experimental Cardiology Unit, University of Bergen, Norway. Correspondence and requests for reprints to Prof. Jan Erik Nordrehaug, Haukeland University Hospital, Department of Heart Disease, N-5021 Bergen, Norway. Tel: +47 5597 2172; fax: +47 5597 5150; e-mail: jeno@haukeland.no Received 1 April 2004 Revised 6 July 2004 Accepted 9 July 2004 Introduction The increasing number of patients with refractory angina and coronary artery disease not amenable to traditional methods of revascularization has led to the development of new therapeutic approaches. Current data indicate that transmyocardial laser revascularization (TMR) via thor- acotomy or the more recent percutaneous myocardial laser revascularization may provide these patients with improvements in angina symptoms and there is some evidence also of improved myocardial perfusion [1–6]. The mechanisms by which these techniques reduce anginal symptoms are not fully understood. Two blinded clinical studies using different laser sources have excluded [7] or not excluded [8] a placebo effect as the only mechanism. Conflicting results have also been reported for a denervation effect [9,10]. The initial hypothesis that myocardial perfusion should be estab- lished via direct connections from the left ventricular cavity to myocardial sinusoids through patent channels [11,12] has not been completely refuted [13–19], although sequential temporal studies were not per- formed. Previous studies have shown that transmyocardial revascularization using either laser or mechanical punc- ture was associated with significantly elevated vascular endothelial growth factor (VEGF) expression and micro- vascular densities in treated areas [20,21]. It is well known that during the inflammatory and proliferating phases of wound healing, there is a significant up- regulation of several growth factors in order to promote angiogenesis. Growth factors promote the proliferation of endothelial cells engaged in angiogenesis and induce the formation of capillary-like tubes of microvascular en- dothelial cells [21]. Extra Domain-A cellular fibronectin (ED-AcFN) is a high molecular weight glycoprotein, which serves as a bridge between cells and interstitial collagen meshwork, and influences diverse processes including cell growth, adhesion, migration and wound repair [22]. Extra Domain-A cellular fibronectin, when 0954-6928  c 2004 Lippincott Williams & Wilkins Copyright © Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.