Identifying and Overcoming Obstacles in Angiogenic Gene Therapy for Myocardial Ischemia:

Relationship between thrombospondin-1, endostatin, angiopoietin-2, and coronary collateral development in patients with chronic total occlusion

This study is aimed to investigate whether serum angiostatic factors (thrombospondin-1 [TSP-1] and endostatin) or angiogenic factors (angiopoietin-2 [Ang-2]) are related to coronary collateral vessel development in patients with chronic total occlusion (CTO).A total of 149 patients were enrolled in the study, and 39 patients with coronary artery disease but without significant stenosis were included in control group. In 110 patients with CTO lesion, 79 with Rentrop grades 2 to 3 collaterals were grouped as good collateral, while 31 with Rentrop grades 0 to 1 collaterals were grouped as poor collateral. Serum TSP-1, endostatin, and Ang-2 levels were studied.Serum endostatin level was significantly higher in poor collateral group compared with control group and good collateral group, respectively (96.2 ± 30.4 vs 77.8 ± 16.5 ng/mL, P = 0.007; 96.2 ± 30.4 vs 81.2 ± 30.4 ng/mL, P = 0.018). In multivariate analysis, decreased serum endostatin level was independently related to good coronary collateral development. Serum TSP-1 level was lower in patients with CTO compared with control group. However, no difference in TSP-1 level was detected between poor and good collateral group. The serum Ang-2 level did not show a significant difference among 3 groups.Circulatory endostatin may be a useful biomarker for coronary collateral development and potential target for therapeutic angiogenesis in patients with CTO.

Angiogenic gene therapy for refractory angina

INTRODUCTION

Stimulation of coronary collateral vessel growth by therapeutic angiogenesis (TA) offers an alternative treatment option for patients with refractory angina. Several TA modalities, including delivery to the heart of angiogenic growth factors (proteins or genes) and cells have been tested in clinical trials in the past two decades, but so far none of them resulted in significant therapeutic efficacy in large scale studies. This review attempts to identify the main obstacles hindering clinical success and recommends measures to overcome them in the future.

AREAS COVERED

After stating the medical need and rational for TA, and listing and briefly discussing past and current TA clinical trials, three main areas of obstacles are described: conceptual questions, technical limitations and clinical design uncertainties. Based on scientific and technical advances and lessons learned in past clinical trials, potential solutions to overcome some of these obstacles are proposed.

EXPERT OPINION

Several success criteria are identified, which apply to any TA approach of choice. It is emphasized, that each of these criteria needs to be met in future clinical trials to have a chance of therapeutic success.