Histological analysis
thrombus
PROLIFERATION, SEPARATION, THROMBUS
Histological analysis of the anastomosis site was conducted on vessel tissue harvested at the last patency evaluation (T1W or T2W for veins and arteries, respectively) just prior to sacrifice the animal. The tissue was collected in a closed-circuit disposable container pre-filled with 4% formaldehyde solution. The histological evaluation was performed by AnaPath Services GmbH (Liestal, Switzerland). The sections were stained with hematoxylin and eosin, as well as with Masson’s trichrome. A semi-quantitative histopathological analysis was performed for each vein and artery segment on the stained sections according to an adapted ISO 10993-6:2016(E) scoring system (Supplementary Table A Principal Component Analysis (PCA) was carried out using histological data with the aim to detect if there were different histological profiles in between all robotic and manual anastomosis carried out in all veins and arteries. PCA allows analyzing data sets that contain a variety of characteristics per observation; this allows data to be interpreted as a set while conserving joint information. PCA is used to reduce the dimensionality of the data set and allow simplified visualization of this multidimensional data. This analysis takes all the values of the histological variables as input and combines them to evaluate the degree of separation among data points in a low-dimensionality scatter plot. The three main histological variables were endothelial loss, fibrin/platelet thrombus, and intimal proliferation. We have used the first principal two components (PC1 and PC2) to plot the data in two dimensions and visually identify the closely related groups of data points: those related to robotic intervention and those related to manual intervention.