Bioactive surface modification of polycaprolactone using MG63-conditioned medium can induce osteogenic differentiation of mesenchymal stem cells

We demonstrated an approach that modifies the scaffold surface with a range of molecules, simultaneously conjugated to the scaffold by a single treatment with concentrated conditioned medium (CM), inducing mesenchymal stem cells (MSC) to differentiate into osteogenic lineages. We first show that the CM from MG63 cells is capable of inducing the desired MSC differentiation over 7 days. We then analyze how the biodegradable polymer polycaprolactone (PCL) can be used as the scaffold. Using a CO₂ plasma treatment, it is possible to conjugate MG63 CM proteins onto the PCL film surface, and we show a gradual release of protein from such a modified PCL scaffold. Finally, we verified cell differentiation and marker expression of MSCs grown on the modified PCL and show that osteogenic markers, including alkaline phosphatase and Runx2 mRNA, are significantly upregulated. Immunostaining also shows a strong expression of the Runx2 protein. Our study shows that the differentiation effects of a condition medium can be preserved when its content is used to modify the surface of polymer scaffolds. This approach may be further applied for the differentiation of various cell lines, and it provided a first step toward growing MSCs on more complex scaffold shapes aimed at therapeutic uses.