Porous scaffolds have been employed for decades in the biomedical field where researchers have been seeking to produce an environment which could approach one of the extracellular matrixes supporting cells in natural tissues. Such three-dimensional systems offer many degrees of freedom to modulate cell activity, ranging from the chemistry of the structure and the architectural properties such as the porosity, the pore, and interconnection size. All these features can be exploited synergistically to tailor the cell–material interactions, and further, the tissue growth within the voids of the scaffold. Herein, an overview of the materials employed to generate porous scaffolds as well as the various techniques that are used to process them is supplied. Furthermore, scaffold parameters which modulate cell behavior are identified under distinct aspects: the architecture of inert scaffolds (i.e., pore and interconnection size, porosity, mechanical properties, etc.) alone on cell functions followed by comparison with bioactive scaffolds to grasp the most relevant features driving tissue regeneration. Finally, in vivo outcomes are highlighted comparing the accordance between in vitro and in vivo results in order to tackle the future translational challenges in tissue repair and regeneration.

The advances in 3D printed silicone (PDMS: Polydimethylsiloxane) implants provide an outlook for personalized implants with highly accurate anatomical conformity. However, a potential adverse effects such as granuloma formation due to immune reactions still exists. One potential way of overcoming this problem is the control of implant/host interface using immunomodulatory coatings.In this study, a new cytokine cocktail composed of interleukin 10 and prostaglandin-E2 was designed to decrease the adverse immune reaction and promote tissue integration by fixing macrophage into M2 pro-healing phenotype for a long term. In vitro, the cytokine cocktail was able to keep the secretion of pro-inflammatory cytokines (TNF-α and IL-6) at a low level and induced the secretion of IL-10 and the upregulation of stabilin-1 (endocytotic scavenger receptor expressed by M2 macrophage). This cocktail was then loaded in a gelatin based hydrogel to develop an immunomodulatory material that can be used as a coating of a medical device. The efficacy of this coating was demonstrated in an in vivo rat model during reconstruction of a tracheal defect by 3D printed silicone implants. The coating was stable on silicone implants over 2 weeks and the controlled release of cocktail components was achieved for at least 14 days. In vivo, only 33% of the animals with bare silicone implant survived whereas 100% survived with the implant equipped with the immunomodulatory hydrogel. The presence of the hydrogel and the cytokine cocktail diminished the thickness of the inflammatory tissue, the intensity of both acute and chronic inflammation, overall fibroblastic reaction, oedema presence and fibrinoid formation (assessed by histology) and lead to a 100% survival rate. At systemic level, the presence of immunomodulatory hydrogel decreased significantly pro-inflammatory cytokines like TNF-α, IFN-γ, CXCL1 and MCP-1 levels at day 7 and IL-1α, IL-1β, CXCL1 and MCP-1 levels at day 21. The ability of this new immunomodulatory hydrogel to control the level of inflammation once applied on a 3D printed silicone implant has been demonstrated. Such thin coatings can be applied to any implants or scaffolds used in tissue engineering to diminish the initial immune response, improve integration and functionality of these materials and finally decrease potential complications related to their presence.

The development of technologies that allow us to reduce CO 2 emissions is mandatory in today's society. In this regard, we present herein a comparative study of CO 2 adsorption over three types of materials: zeolites, layered double hydroxides (LDH), and zeolites coated LDH composites. The influence of the zeolite Si/Al ratio on zeolites sorption capacity along with the presence of mesopores was investigated. By comparing these results with the well-known performance of LDHs, we aim to provide insights on the factors that may influence the CO 2 capture capacity over zeolites, thus providing useful tools for tuning their properties upon post-treatments.

Full-scale cell penetration within porous scaffolds is required to obtain functional connective tissue components in tissue engineering applications. For this aim, we produced porous polyurethane structures with well-controlled pore and interconnection sizes. Although the influence of the pore size on cellular behavior is widely studied, we focused on the impact of the size of the interconnections on the colonization by NIH 3T3 fibroblasts and Wharton's jelly-derived mesenchymal stem cells (WJMSCs). To render the material hydrophilic and allow good material wettability, we treated the material either by plasma or by polydopamine (PDA) coating. We show that cells weakly adhere on these surfaces. Keeping the average pore diameter constant at 133 μm, we compare two structures, one with LARGE (52 μm) and one with SMALL (27 μm) interconnection diameters. DNA quantification and extracellular matrix (ECM) production reveal that larger interconnections is more suitable for cells to move across the scaffold and form a three-dimensional cellular network. We argue that LARGE interconnections favor cell communication between different pores, which then favors the production of the ECM. Moreover, PDA treatment shows a truly beneficial effect on fibroblast viability and on matrix production, whereas plasma treatment shows the same effect for WJMSCs. We, therefore, claim that both pore interconnection size and surface treatment play a significant role to improve the quality of integration of tissue engineering scaffolds.