## 4 Discussion  
The present study introduces an ACM, which was designed and built to mimic the human circulatory system. With the use of an artificial heart, it was possible to simultaneously reconstruct different ejection volumes, frequencies of pulsation, and ejection pressures. The system comprised a transparent, rectangular, container for vessel placement (the vessel chamber) that acts as an incubator by maintaining a constant temperature and constant CO\({}_{2}\) concentration. Moreover, because in the human body there is a higher pressure within the abdominal cavity, our device was designed to maintain an interior pressure that acts on the vessel. Finally, with the use of our vision system, we monitored changes in the spatial configuration of the analyzed vessels, which have been validated with clinical data. Our results demonstrated that simulation of physiological conditions of blood hemodynamics in an ex vivo bioengineering reactor requires vascular grafts, as the application of silicon tubes resulted in lower diameter changes and a decrease of wall displacement compared to human common iliac arteries. To the best of our knowledge, our ACM is the first model capable of analyzing these factors, because the existing vascular bioreactors lack the monitoring of mechanical properties of investigated vessels so far. Moreover, to date, there are no data presenting the application of vision systems for 3d projection of a vessel's wall behavior after placement in bioengineering reactors. Figure 8: Scatterplot graphic representation of [PERSON]’s correlation factors rho (-) for the analyzed vessels for W\({}_{\mathrm{d}}\) (mm) as function of FP and EV. W\({}_{\mathrm{d}}\) as function of EV: (**a**) iliac arteries (rho = 0.976); (**c**) silicon tubes (rho = 0.963). W\({}_{\mathrm{d}}\) as function of FP: (**b**) iliac arteries (rho = 0.968); (**d**) silicon tubes (rho = 0.966). Two types of vessels were analyzed, each group consisted of \(n=5\). For all analyzes, \(p<0.05\). An ex vivo vessel culture system has been built for the replication of hemodynamic factors in the coronary circulation by [PERSON] et al. [12; 14]. This system is at least somehow comparable to our ACM. However, effects of altered flow conditions have only been investigated in human saphenous veins after coronary artery bypass grafting [13]. [PERSON] et al. also reported on an ex vivo bioreactor that allowed an evaluation of cellular interactions in the carotid artery of pigs under controlled physiologic conditions [2]. Oxygen saturation and temperature have been successfully controlled. The drawback of that study was that they were not able to record flow rates from the carotid arteries due to media leakages. In our study, we applied dedicated vessel stabilizers that prevented media leakage and allowed interposition of vascular grafts of different materials. Moreover, in our study, different physiological and pathological conditions such as frequencies of pulsation and ejection volumes were taken into account to mimic the in vivo vascular conditions. We observed that both parameters had a similar impact on vessel wall behavior. Higher frequencies of pulsation and ejection volumes resulted in more pronounced dilatation of an interposed vessel's diameter and wall displacement. These findings were in line with [PERSON] et al., who undertook experiments under venous and arterial hemodynamic conditions for one, two, and four days [16]. Similar observations were made by [PERSON] et al., who investigated the shear stress of iliac arteries in anaest pigs [4]. Increases of diameter and wall shear stress were accompanied by an increase of flow in arteries. Dedicated artificial \"hearts\" were introduced into the literature to reconstruct various physiological conditions. With the use of such a device, it was possible to simulate arbitrary hemodynamics reflecting real blood flow character. Most of the authors reconstructed blood hemodynamic with the use of commercially available pumps that did not allow maintaining various flow conditions. [PERSON] et al.