The project has been completed in all its objectives. We successfully developed a tri-compartment construct with the potential to regenerate osteochondral tissue.
For the first compartment of CELL HYBRIDGE, we developed hydrogels with different biological moieties that were screened to maintain cell quiescence. Cell quiescence was achieved, dependent on the chemistry composition of the hydrogels. The biological mechanisms behind the observed cell quiescence was elucidated and correlated to hydrogel physico-chemical properties.
For the second compartment of CELL HYBRIDGE, we developed different methods to control the fiber size, shape, and surface properties, to influence cell proliferation. We found a way to vary these scaffolds parameters spanning from obtaining homogeneous scaffolds to gradient scaffolds. We found that biological functionalization is not always needed to enhance cell proliferation. We correlated our findings to the biological mechanisms behind enhanced (or maintained) cell proliferation. We developed a method to increase cell migration capacity throughout the scaffolds, achieving full cell migration over 2mm in thickness in vivo, which is unreported so far with nanofibrillar meshes.
We found that cells in 3D express much lower levels of lamins compared to conventional 2D cultures, which we correlated to a specific focal adhesion protein. Such differential expression of lamins seems also to be connected to a differential migratory potential of cells.
For the third compartment of CELL HYBRIDGE, we developed protocols to bind biological moieties to 3D printed scaffolds and create inverse gradients of osteogenic and chondrogenic peptides. We also conducted proteomics studies to discover the protein signature on 3D scaffolds for osteochondral differentiation. Interestingly, we seemed to have found an indication that the protein signature in osteochondral cell differentiation is independent from the biomaterial chemistry analyzed, which may shed light on a broader applicability to different biomaterial scaffolds of the methodology that we have here developed.
We successfully integrated the 3 different compartments, obtaining the final CELL HYBRIDGE construct. In vitro studies showed that it was possible to obtain selective osteogenic and chondrogenic cell differentiation moving from the bony side to the cartilage side of the osteochondral scaffolds. In vivo studies further confirmed the in vitro studies both in small animals in an ectopic location as well as in large animals in an orthotopic skeletal location. Furthermore, small animal studies also allowed us to further confirm the biocompatibility of all compartments, used alone or in the integrated CELL HYBRIDGE construct.
Results were disseminated at several international and national conferences over the 5 years of duration of the project, extending the ERC results not only to European events, but also to the other continents. 3 PhD. thesis will be completed within the course of the next months. Originating from the work of the team, 12 scientific papers have already been published in international peer reviewed journals, and approximately 10-12 more are expected.
