Impact of a Porous Si-Ca-P Monophasic Ceramic on Variation of Osteogenesis-Related Gene Expression of Adult Human Mesenchymal Stem Cells

This work evaluates in vitro the influence of a new biocompatible porous Si-Ca-P monophasic (7CaO·P2O5·2SiO2) ceramic on the cellular metabolic activity, morphology and osteogenic differentiation of adult human mesenchymal stem cells (ahMSCs) cultured in basal growth medium and under osteogenic inductive medium. Alamar Blue Assay and FESEM were carried out in order to monitor the cell proliferation and the shape of the cells growing on the Si-Ca-P monophasic ceramic during the study period. The osteogenic differentiation of ahMSCs was investigated by means of immunofluorescent staining (osteocalcin, osteopontin, heparan sulphate and collagen type I expression), quantitative reverse transcription polymerase chain reaction (qRT-PCR) (integrin-binding sialoprotein, osteocalcin, alkaline phosphatase, osteopontin, osteonectin, runt-related transcription factor 2 and collagen type I) and expression of surface markers (CD73, CD90 and CD105). We could check osteogenic differentiation in ahMSCs growing under the influence of Si-Ca-P monophasic ceramics itself, but especially when growth medium was replaced by osteogenic medium in the culture conditions. These results allowed us to conclude that the new Si-Ca-P monophasic scaffold greatly enhanced ahMSCs proliferation and osteogenic differentiation; therefore, it may be considered to be employed as a new bone graft substitute or scaffold for bone tissue engineering

Morphological and Structural Study of a Novel Porous Nurse’s A Ceramic with Osteoconductive Properties for Tissue Engineering

The characterization process of a new porous Nurse’s A ceramic and the physico chemical nature of the remodeled interface between the implant and the surrounding bone were studied after in vivo implantation. Scaffolds were prepared by a solid-state reaction and implanted in New Zealand rabbits. Animals were sacrificed on days 15, 30, and 60. The porous biomaterial displayed biocompatible, bioresorbable, and osteoconductive capacity. The degradation processes of implants also encouraged osseous tissue ingrowths into the material’s pores, and drastically changed the macro- and microstructure of the implants. After 60 healing days, the resorption rates were 52.62% ± 1.12% for the ceramic and 47.38% ± 1.24% for the residual biomaterial. The elemental analysis showed a gradual diffusion of the Ca and Si ions from the materials into the newly forming bone during the biomaterial’s resorption process. The energy dispersive spectroscopy (EDS) analysis of the residual ceramic revealed some particle categories with different mean Ca/P ratios according to size, and indicated various resorption process stages. Since osteoconductive capacity was indicated for this material and bone ingrowth was possible, it could be applied to progressively substitute an implant

Nurse’s A-Phase Material Enhance Adhesion, Growth and Differentiation of Human Bone Marrow-Derived Stromal Mesenchymal Stem Cells

The purpose of this study was to evaluate the bioactivity and cell response of a well-characterized Nurse’s A-phase (7CaO·P2O5·2SiO2) ceramic and its effect compared to a control (tissue culture polystyrene-TCPS) on the adhesion, viability, proliferation, and osteogenic differentiation of ahMSCs in vitro. Cell proliferation (Alamar Blue Assay), Alizarin Red-S (AR-s) staining, alkaline phosphatase (ALP) activity, osteocalcin (OCN), and collagen I (Col I) were evaluated. Also, field emission scanning electron microscopy (FESEM) images were acquired in order to visualise the cells and the topography of the material. The proliferation of cells growing in a direct contact with the material was slower at early stages of the study because of the new environmental conditions. However, the entire surface was colonized after 28 days of culture in growth medium (GM). Osteoblastic differentiation markers were significantly enhanced in cells growing on Nurse’s A phase ceramic and cultured with osteogenic medium (OM), probably due to the role of silica to stimulate the differentiation of ahMSCs. Moreover, calcium nodules were formed under the influence of ceramic material. Therefore, it is predicted that Nurse’s A-phase ceramic would present high biocompatibility and osteoinductive properties and would be a good candidate to be used as a biomaterial for bone tissue engineering

In vivo partial cellular reprogramming enhances liver plasticity and regeneration

Mammals have limited regenerative capacity, whereas some vertebrates, like fish and salamanders, are able to regenerate their organs efficiently. The regeneration in these species depends on cell dedifferentiation followed by proliferation. We generate a mouse model that enables the inducible expression of the four Yamanaka factors (Oct-3/4, Sox2, Klf4, and c-Myc, or 4F) specifically in hepatocytes. Transient in vivo 4F expression induces partial reprogramming of adult hepatocytes to a progenitor state and concomitantly increases cell proliferation. This is indicated by reduced expression of differentiated hepatic-lineage markers, an increase in markers of proliferation and chromatin modifiers, global changes in DNA accessibility, and an acquisition of liver stem and progenitor cell markers. Functionally, short-term expression of 4F enhances liver regenerative capacity through topoisomerase2-mediated partial reprogramming. Our results reveal that liver-specific 4F expression in vivo induces cellular plasticity and counteracts liver failure, suggesting that partial reprogramming may represent an avenue for enhancing tissue regeneration