Conversion of adipogenic to osteogenic phenotype using crystalline porous biomatrices of marine origin

Adipogenic and osteogenic cells share part of the early differentiation cascade of mesenchymal stem cells (MSCs). The choice of a mesenchymal precursor cell to differentiate into a particular cell type is dictated by many spatial and temporal cues, including growth factors, neighboring mature cells, and the extracellular matrix (ECM), which plays an important role in bone formation. Whether adipocytes that have initiated differentiation along one lineage can convert into osteogenic lineage by merely interacting with materials having specific surface parameters is unknown. Using crystalline three-dimensional (3D) biomatrices of marine origin (CaCO₃), we explored whether preadipocytes can convert into osteoblasts. Cells (3T3F442A) were seeded on 3D biomatrices of marine origin (Porites lutea). Analyses were made at different time intervals-1, 2, 5, 7, 14, 21, and 28 days post-seeding. Cell characterizations were done using morphological (light microscopy and scanning electron microscopy), histological (Alizarin red, von Kossa and Oil red O staining), enzymatic (alkaline phosphatase activity, and quantitative PCR testing transcript levels of osteocalcin, alkaline phosphatase, core binding factor-1 (Cbfa1), and fatty acid binding protein (aP2). We demonstrated 3T3F442A preadipocyte modulation and differentiation into bone-forming cells when grown on biomatrix of marine origin without addition of other bone morphogenesis inducers. We found an active ossification process typical of osteogenic phenotype as early as 2 days after seeding. It is suggested that this crystalline biomatrix having a particular 3D topology or surface parameters supports fast cellular adhesion, proliferation, and differentiation of preadipocytes to osteogenic phenotype.