Living Bacterial Sacrificial Porogens to Engineer Decellularized Porous Scaffolds

Decellularization and cellularization of organs have emerged as disruptive methods in tissue engineering and regenerative medicine. Porous hydrogel scaffolds have widespread applications in tissue engineering, regenerative medicine and drug discovery as viable tissue mimics. However, the existing hydrogel fabrication techniques suffer from limited control over pore interconnectivity, density and size, which leads to inefficient nutrient and oxygen transport to cells embedded in the scaffolds. Here, we demonstrated an innovative approach to develop a new platform for tissue engineered constructs using live bacteria as sacrificial porogens. E.coli were patterned and cultured in an interconnected three-dimensional (3D) hydrogel network. The growing bacteria created interconnected micropores and microchannels. Then, the scafold was decellularized, and bacteria were eliminated from the scaffold through lysing and washing steps. This 3D porous network method combined with bioprinting has the potential to be broadly applicable and compatible with tissue specific applications allowing seeding of stem cells and other cell types

Improvement of an experimental model of oral biofilm

Objectives: The main aim of our work was to get one step closer to the in vivo conditions. We started from a multispecies static biofilm model containing five different bacteria, implementing specific enhancements. Our second goal was to improve the analysis of such biofilms regarding collection and identification. Material and Methods: We started from a multispecies static model with five oral strains growing on hydroxyapatite discs to improve it on multiple points. We modified culture conditions and added two more strains. We also changed bacteria collection, which evolved from manually scrapping the discs surface to the combination of ultrasonic and mechanical harvesting. In a further another step, we developed a dynamic model implementing the above changes with a continuous supply of medium flow and waste disposal. Different methods have been evaluated to monitor the presence of all the species within the biofilms, and to quantify them: gram staining, PCR, MALDI-TOF-MS, qPCR. Results: The modifications brought to our static model confirmed its reproducibility. Even if improvements need to be made, our dynamic model of oral biofilm is already a good alternative to more sophisticated and expensive models. Conclusions: This new oral biofilm model represents the premises of another way to study the environmental variations effects on bacterial development, its larger application will result in a better understanding of oral health significant factors