A 3D millifluidic model of a dermal perivascular microenvironment on a chip.

The process of angiogenesis plays a pivotal role in skin regeneration, ensuring the provision of nutrients and oxygen to the nascent tissue, thanks to the formation of novel microvascular networks supporting functional tissue regeneration. Unfortunately, most of the current therapeutic approaches for skin regeneration lack vascularization, required to promote effective angiogenesis. Thus, tridimensional models, complemented with specific biochemical signals, can be a valuable tool to unravel the neovascularization mechanisms and develop novel clinical strategies. In this work, we designed and validated a tridimensional microstructured dynamic model of the dermal perivascular microenvironment on a chip. We carried out the fabrication of an array of microstructures by two-photon laser polymerization, then used as a 3D substrate for co-culture of human dermal fibroblasts and endothelial cells. We included the substrate in a miniaturized optically accessible bioreactor (MOAB) which provides the physiological interstitial flow, upon perfusion in the presence or absence of the pro-angiogenic stimuli VEGF and TGF-β1. We determined the parameters to be applied under dynamic conditions by an model simulating individual 3D microenvironments within the bioreactor's chambers. We computed the fluid velocity and wall shear stress acting on endothelial cells along with the oxygen concentration profile, and we chose the most suitable flow rate for maintaining dermal physiological conditions. Experimental results showed the effectiveness of the developed platform as a 3D dynamic model of angiogenesis. This is the first combined experimental and computational study involving chemically stimulated 3D co-cultures for successfully simulating the physiological dermal perivascular microenvironment.