Percutaneous devices (PD) (skin crossing devices) are used in the medical field to connect an extracorporeal medical device to a patient’s organ. These devices exit the patient’s body through a permanent defect in the skin and create an entry point for bacteria, leading to high rates of infections. PDs with controlled pore sizes have been reported to increase skin integration and reduce infection rates. It has been hypothesised that the pores create a micro environment into which skin cells can infiltrate and immune cells can clear from debris. The aim of this study was to test this hypothesis by co-culturing skin and immune cells on scaffolds with various pore sizes.
Scaffolds with different pore sizes were manufactured using a novel additive manufacturing technique, termed melt electrowriting (MEW) and characterised using scanning electron microscopy (SEM). Primary human dermal fibroblasts and THP-1 macrophages were co-cultured on the scaffolds for up to twelve days. Cellular behaviour at different time points was studied using confocal laser scanning microscopy and live imaging.
SEM micrographs showed that the scaffolds had controlled pore sizes, ranging from 3000 µm2 to 13000 µm2. Confocal laser scanning microscopy images revealed that fibroblasts attached to the fibres, spread along the fibres and bridged neighbouring struts throughout the depth of the scaffold. Fibroblasts formed cell sheets in pores with surfaces larger than 8000 µm2. Live imaging revealed that macrophages were present in all pores and capable of infiltrating spaces of 15 µm. These results highlight the importance of porosity to achieve fibroblast infiltration and increase skin integration and macrophage infiltration to clear the pores from debris.