Bone tissue engineering takes part in the complex process of bone healing by combining cells, chemical/physical signals, and scaffolds with the scaffolds providing an artificial extracellular matrix network. The role of the support template for cell activity is crucial to guide the healing process. This in vitro study compared three different poly(D,L-lactic acid) scaffolds obtained by varying the pore size generated by applying different salt leaching processes. The influence of pore dimensions on the extracellular matrix produced by human osteosarcoma-derived osteoblasts (MG63 cell line) seeded on these different materials was analyzed. This study is targeted on the intermediate stage of the bone healing process, where a collagen network is beginning to develop by the growing osteoblasts representing the template for the ultimate stage of bone formation. Imaging analyses assessed by confocal laser microscopy were combined with gene expression measurements of the most common genes involved in the bone healing process. Furthermore, in vitro evaluations were carried out to investigate cell morphology, proliferation, and viability. It was found that the different pore size matrixes can affect extracellular matrix development and that cell organization, collagen I assembly, and mineralization are strictly correlated.
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