gms | German Medical Science

Objectives: Human mesenchymal stem cells (hBMSCs) are gaining more importance in the field of regenerative medicine to treat several diseases, for instance bone defects. Although hBMSCs show many promising characteristics for a low-risk use in therapy, some donor cells show a significantly reduced osteogenic differentiation (OD) potential which remains challenging. Previous studies have shown that reactive oxygen species (ROS) result in a higher oxidative stress level which might inhibit the osteogenic differentiation of osteogenically dysfunctional hBMSCs. In our present work, we especially examined hBMSCs which are osteogenically dysfunctional and consequently exhibit a reduced OD potential (low-responder cells; LR-hBMSCs). Since we found out that the addition of catalase results in a restored OD potential of LR-hBMSCs, we assessed impacts of related anti-oxidative approaches on their OD potential.

Methods: Human BMSCs were acquired from our cooperation partners at the medical school Hannover. To induce OD, Dexamethasone (500 nM), ascorbate (50 µM) and β-glycerophosphate (10 mM) were added to the media. We assessed the OD potential by detecting and quantifying calcified matrix, alkaline phosphatase activity and expressions of osteogenesis-specific proteins. Catalase (125U), MnTBAP (25 µM) and EUK134 (25 µM), were used as antioxidants. The expressions of redox-relevant proteins and mRNA (catalase, superoxide dismutase1/2 (SOD1/2), NAPDH oxidase 4 (NOX4), forkhead box protein O1 (FoxO1), osteonectin (SPARC), Osterix, Collagen type 1 (COL1a1)) were quantified by Western blot analysis, qRT-PCR and immunohistochemistry (IHC).

Results and conclusion: As the formation of calcified matrix is significantly enhanced, the missing osteogenic differentiation potential of LR-BMSC cultures could be completely restored by the catalase treatment (125 U). The observed catalase-regenerated osteogenic potential was paralleled by significantly enhanced cellular catalase and superoxide dismutase (MnSOD) protein expression, and was accompanied by a tendentially reduced NADPH oxidase 4 (NOX4) expression, whereas the expression of the transcription factor forkhead box protein O1 (FoxO1) remained unaffected. Furthermore catalase-restored potential of osteogenic differentiation clearly correlated with an increase of SPARC and COL1a1, as compared to untreated LR-hBMSCs. In contrast, the other anti-oxdidative approaches do not result in a significant restoration of the impaired OD potential of LR-hBMSCs. In conclusion, our results give new interesting hints on the role of catalase as a key antioxidant during the osteogenesis in a yet not fully understood osteogenesis-relevant redox-network. Catalase with the capability to degrade hydrogen peroxide as a physiological important ROS or an element thereof might represent a pivotal molecular target to restore osteogenically dysfunctional LR-hBMSCs.