Invitro and Invivo Study of PCL-Hydrogel Scaffold to Advance Bioprinting Translation in Microtia Reconstruction

Background: Bioprinting has shown promise in the area of microtia reconstruction. However clinical translation has been challenged by the lack of robust techniques to control delivery of stem cells. Hybrid printing allowing multiple materials, both cell and support, to be printed together may overcome these challenges. Objective: This study assesses the degradation behavior and tissue compatibility of hybrid scaffolds (PCL-Hydrogel) compared to single material Polycaprolactone (PCL) scaffolds in-vitro and in-vivo. Sheep demonstrate similar fascial anatomy to humans. This is the first reported study using a sheep model to study hybrid scaffolds for microtia. Methods: PCL and PCL-Hydrogel samples of increasing porosity were subjected to an accelerated enzymatic degradation assay to study degradation behavior in-vitro. In addition, a 6-month study using Merino-Dorset sheep was conducted to compare the biological reaction of the host to PCL and PCL-hydrogel scaffolds. Results: In-vitro degradation showed homogenous degradation of the scaffold. PCL presented the dominating influence on degradation volume compared to hydrogel. In-vivo, there was no evidence of skin irritation or infection over 6 months in both control and test, though PCL-hydrogel scaffolds showed higher levels of tissue ingrowth. Conclusion: Homogenous degradation pattern of porous scaffolds may create less surrounding tissue irritation. Hybrid scaffolds had good biological compatibility and showed better tissue ingrowth than PCL alone.