Response of Different Stem Cells to Biphasic Calcium Phosphate Bioceramics

Biphasic calcium phosphate bioceramics (BCP) associated or not with mesenchymal stem cells (MSC, isolated from the bone marrow), were shown to elicit osteo-chondrogenic response after implantation in orthotopic and heterotopic sites. Objectives: This study aimed to compare the response of stem cells isolated from three different tissues (bone marrow, adipose tissue and dental pulp) to BCP scaffolds as well as to determine the osteoinductive property of the BCP. Methods: MSC and adipose derived stem cells (ADSC) purchased from Lonza (USA), and dental pulp stem cells (DPSC) isolated from permanent teeth (NYU College of Dentistry) and BCP scaffolds (provided by EINCO Biomaterial Ltda, Brazil) were used in this study. Cells were seeded onto BCP at 3x104 cells/cm2, and cultured in control and osteogenic media. For the control group, the stem cells were cultured directly on polystyrene plates. Cell adhesion and morphology were determined using SEM; cell viability by XTT Assay (Biotinum, Inc. CA, USA), cell proliferation by DNA content (Quanti-iT™ Pico Green® dsDNA Assay Kit, Invitrogen, USA) and the expression of the genes RUNX2, SOX9, PPARgamma and SOX2, by RT-PCR. Statistical analysis was performed using Tukey test (p<0.05). Results: The BCP allowed cell attachment and proliferation. An increased expression of RUNX2 by cells cultured onto the BCP, in control media, was mostly observed with DPSC. A concomitant increase in the expression of RUNX2 and PPARgamma, in the osteogenic medium, regardless the cell type, was also observed. Conclusions: The BCP scaffold used in this study showed osteoinductive property and has potential as stem cells carrier. The association of dental pulp stem cells with BCP scaffolds might represent a therapeutic alternative for the reconstruction of critical size bone defects. The relation between RUNX2 and PPARgamma expression requires further studies. [Supported by Einco Biomaterial Ltda, Brazil and the Calcium Phosphate Research Funds (RZLeGeros), NYU]