Tissue engineering is a branch of regenerative medicine, which comprises the combination of biomaterials, cells and other bioactive molecules to regenerate tissues. Biomaterial scaffolds act as substrate and as physical support for cells and they can also reproduce the extracellular matrix cues. Although tissue engineering applications in cellular therapy tend to focus on the use of specialized cells from particular tissues or stem cells, little attention has been paid to endothelial progenitors, an important cell type in tissue regeneration. We combined 3D printed poly(lactic acid) scaffolds comprising two different pore sizes with human adipose-derived stromal cells (hASCs) and expanded CD133+ cells to evaluate how these two cell types respond to the different architectures. hASCs represent an ideal source of cells for tissue engineering applications due to their low immunogenicity, paracrine activity and ability to differentiate. Expanded CD133+ cells were isolated from umbilical cord blood and represent a source of endothelial-like cells with angiogenic potential. Fluorescence microscopy and scanning electron microscopy showed that both cell types were able to adhere to the scaffolds and maintain their characteristic morphologies. The porous PLA scaffolds stimulated cell cycle progression of hASCs but led to an arrest in the G1 phase and reduced proliferation of expanded CD133+ cells. Also, while hASCs maintained their undifferentiated profile after 7 days of culture on the scaffolds, expanded CD133+ cells presented a reduction of the von Willebrand factor (vWF), which affected the cells’ angiogenic potential. We did not observe changes in cell behavior for any of the parameters analyzed between the scaffolds with different pore sizes, but the 3D environment created by the scaffolds had different effects on the cell types tested. Unlike the extensively used mesenchymal stem cell types, the 3D PLA scaffolds led to opposite behaviors of the expanded CD133+ cells in terms of cytotoxicity, proliferation and immunophenotype. The results obtained reinforce the importance of studying how different cell types respond to 3D culture systems when considering the scaffold approach for tissue engineering.

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Ultrastructural difractometric and chemical evaluations of calcium partially stabilized zirconium (Ca-PSZ) implants were performed in an in vivo study on animals in order to evaluate its biological behaviour. The chemical-morphological investigations demonstrated the presence of an osteogenetic activity at the bone-biomaterial interface. The new-osteogenesis was preceded by the formation of a loose connective tissue around the implants. This mesenchymal-type tissue without a capsular organization, allowing modulation of the mechanical forces to which the implant is subject, could be considered a positive event in the osteogenetic process and not a sign of future failure of the implant. Finally, microanalytical investigations carried out on non-implanted and implanted Ca-PSZ tools suggested that the surface of this ceramic material does not undergo modification once it has been inserted in the biological environment (12 months).

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The present study reports on a biological model based on fibroblast proliferation applied to 3 different types of flat-plate dialysis membrane, in order to ascertain whether the artificial materials currently used in hemodialysis cause in vitro cellular proliferation. The study plan we followed involved plate membrane isolation from non-used dialyzers and used dialyzers, observed through scanning electron microscopy (SEM) both before and after testing with human fibroblasts by means of cell culture. Fibroblast growth was assessed by phase contrast light microscopy examination and cytometric DNA content evaluation. Our investigations proved that the artificial materials we considered interact with fibroblast cultures. Noticeable proliferative response was observed both after contact with unused material and on mediation by the protein layer absorbed on the membrane surface at the end of dialysis sessions. In this last case fibroblast proliferative activity appeared higher than that observed with unused membranes, showing that the soluble molecules entrapped in the protein layer appeared able to exert a biological activity even in vitro tests.