Background The Abdominal Aortic Aneurysm-Express Biobank Study (AAA) started in 2003 and and now includes over 1,000 patients who underwent open surgical repair of arterial aneurysms, the majority on aortic aneurysms at two Dutch tertiary referral centers. Details of the study design were described before. Briefly, blood and aneurysm material were obtained during surgery and stored at -80℃; tissue material is routinely used for standardised (immuno)histochemical analysis. We routinely perform the following stainings: hematoxilin & eosin (HE), elastic van Giesson (EVG), picro sirius red (collagen), smooth muscle alpha-actin (SMA, smooth-muscle cells), CD68 (macrophages), CD3 (T lymphocytes), CD20 (B lymphocytes), CD138 (plasma cells) and von Willebrand factor (vasa vasorum). All stainings are scored semiquantitatively on a scale from 0 to 3 (0 being no staining, 1 minor, 2 moderate and 3 heavy staining). Structural wall components (elastin, collagen, vasa vasorum) and cells (smoothmuscle cells, macrophages, T lymphocytes, B lymphocytes and plasma cells) are scored on a 0 to 3 scale separately for intima, media and adventitia. All histological observations were performed by the same dedicated technician. Clinical data is collected through standardised questionnaires and supplemented by querying electronic health records when needed.

Ethical approval for this study (TME/C-01.18) was provided by the Medical Research Ethics Committee of University Medical Center Utrecht, Utrecht, The Netherlands on 10 April 2002, and all research was conducted according to the principles of the Declaration of Helsinki (59th amendment, Seoul 2008) and in accordance with the Dutch Medical Research Involving Human Subjects Act (WMO).

Important notice on availability of data - Whole-slide images (WSI) are available for the (immuno)histochemical stainings. The amount of data is huge, on average 1Gb size per WSI. These are accessible through ExpressScan. - Genetic (GWAS chip) data are described here and accessible through this repository [NOT AVAILABLE YET].

There are restrictions on use by commercial parties, and on sharing openly based on (inter)national laws and regulations and the written informed consent. Therefore these data (and additional clinical data) are only available upon discussion and signing a Data Sharing Agreement (see Terms of Access) and within a specially designed UMC Utrecht provided environment.