Creation of bony microenvironment with CaP and cell-derived ECM to enhance human bone-marrow MSC behavior and delivery of BMP-2

Extracellular matrix (ECM) comprises a rich meshwork of proteins and proteoglycans, which not only contains biological cues for cell behavior, but is also a reservoir for binding growth factors and controlling their release. Here we aimed to create a suitable bony microenvironment with cell-derived ECM and biodegradable beta-tricalcium phosphate (beta-TCP). More specifically, we investigated whether the ECM produced by bone marrow-derived mesenchymal stem cells (hBMSC) on a beta-TCP scaffold can bind bone morphogenetic protein-2 (BMP-2) and control its release in a sustained manner, and further examined the effect of ECM and the BMP-2 released from ECM on cell behaviors. The ECM was obtained through culturing the hBMSC on a beta-TCP porous scaffold and performing decellularization and sterilization. SEM, XPS, FTIR, and immunofluorescent staining results indicated the presence of ECM on the beta-TCP and the amount of ECM increased with the incubation time. BMP-2 was loaded onto the beta-TCP with and without ECM by immersing the scaffolds in the BMP-2 solution. The loading and release kinetics of the BMP-2 on the beta-TCP/ECM were significantly slower than those on the beta-TCP. The beta-TCP/ECM exhibited a sustained release profile of the BMP-2, which was also affected by the amount of ECM. This is probably because the beta-TCP/ECM has different binding mechanisms with BMP-2. The beta-TCP/ECM promoted cell proliferation. Furthermore, the BMP-2-loaded beta-TCP/ECM stimulated reorganization of the actin cytoskeleton, increased expression of alkaline phosphatase and calcium deposition by the cells compared to those without BMP-2 loading and the beta-TCP with BMP-2 loading. (C) 2011 Elsevier Ltd. All rights reserved.