Bone is composed of extracellular matrix (ECM) that physically supports bone cells and actively influences their behaviour and differentiation. In the bone marrow, Mesenchymal Stem Cells (MSCs) are in close contact with the ECM and bone cells. Due to their osteogenic differentiation potential and paracrine activity, MSCs are promising candidates for bone tissue engineering applications. The impact of the ECM on MSC behavior was investigated by using an in vitro model of devitalised ECM, to exploit it as a natural biomaterial to enhance the osteogenic potential of MSCs. Human MSCs were differentiated into osteoblasts and devitalised by freeze-thaw cycles and DNAse treatment to produce the ECM. Its proteomic composition was analysed by mass spectrometry. Next, MSCs were seeded on the ECM and monitored for cell adhesion, proliferation, osteogenic differentiation and mineralisation. The MSC-derived ECM was metabolic inactive. 846 proteins were detected: significantly enriched ones (P<0,01) were involved in ECM structure, cell-matrix adhesion, related to mitochondrial activity and calcium binding. The ECM significantly enhances MSC adhesion already 2 hours after seeding (number of focal adhesions/cell area (FA/um2) on ECM=4,9−04 and on plastic=2,6-05; P<0,001). ECM induces a temporal increase of MSC proliferation: the percentage of proliferating cells was about 3 fold higher 24 hours after seeding MSCs on ECM compared with plastic (P<0,001). MSCs on ECM are accelerated in their osteogenic differentiation compared to MSCs on plastic: the peak of Alkaline Phosphatase was detected earlier and 5 fold increased (P<0,01). This results in a significantly enhanced mineralisation (P<0,001): quantification of Alizarin Red Staining shows that MSCs cultured on the ECM for 13 days mineralised, whereas the control did not yet. The devitalised ECM increased adhesion of MSCs and temporally enhanced their proliferation. MSC osteogenic differentiation was accelerated, enhancing the mineralisation. These properties make the devitalised ECM a suitable microenvironment to improve MSC utilisation for bone regeneration. Identification of key molecules responsible for the observed effects will unravel their potential for using in bone tissue repair applications
Disclosure: The authors declared no competing interests. This work was funded by NIRM.