Superoxide dismutase and catalase significantly improve the osteogenic differentiation potential of osteogenetically compromised human adipose tissue-derived stromal cells in vitro.

Mesenchymal stromal cells (MSCs) play a pivotal role in modern therapeutic approaches of bone defect regeneration. A complication that is steadily increasing due to demographic population developments is an age-related disorder of the osteogenic differentiation potential (ODP) of MSCs. In the present in vitro study we have evaluated the impact of reactive oxygen species (ROS) and antioxidants on ODP of "normal healthy" as well as osteogenetically compromised human adipose tissue-derived stromal cells (ASC). We show that although ASC exhibit a marked ODP, a significant number of ASC cultures showed a retarded osteogenesis. These so-called "non-responder"-ASC cultures (NR-ASC) expressed an antigenic phenotype identical to that of the well osteogenically differentiating "responder"-ASCs (R-ASC), but NR-ASC significantly correlated with the older age of their donors as well as with a significantly higher intracellular generation of ROS. Furthermore, we found that treatment of the cell cultures with low concentration of H2O2 seemed to promote osteogenic differentiation but higher H2O2 concentration strongly reduced osteogenesis in all ASC cultures. Additionally, we found that exogenously applied superoxide dismutase (SOD) or catalase completely restored the impaired ODP of NR-ASC, whereas ascorbate, glutathione, N-acetylcysteine or a water soluble vitamin E derivate did not show any relevant effects. Our results suggest that aging-related increases in oxidative stress, especially due to H2O2, can severely impair the ODP of ASC whereas SOD or catalase almost completely corrected this disorder. Our findings point to novel osteo-therapeutic aspects of catalase and SOD and open up new approaches to ASC-based regeneration of bone defects.

Blue light irradiation and its beneficial effect on Dupuytren's fibroblasts.

Dupuytren's contracture is a fibroproliferative disorder affecting the palmar fascia of the hand. Most affected are the ring fingers, and little fingers of middle-aged men. Symptomatic for this disease is the increased proliferation and differentiation of fibroblasts to myofibroblasts, which is accompanied by an elevated α-SMA expression. The present study evaluated the therapeutic benefit of blue light (λ = 453 nm, 38 mW/cm2, continuous radiance, spot size 10-12 cm2) as well as the molecular mechanism mediating this effect. It could be determined that blue light significantly diminished the induced α-SMA protein expression in both normal palmar fibroblasts and Duypuytren's fibroblasts. The beneficial effect mediated by this irradiance, radiant exposure and wavelength was associated with an elevated reactive oxygen species generation. Furthermore, the data underlines the potential usefulness of blue light irradiation as a promising therapy option for Dupuytren's disease, especially for relapse prevention, and may represent a useful strategy to treat further fibrotic diseases, such as keloids, hypertrophic scarring, and scleroderma.

Deficiency of the clock gene Bmal1 affects neural progenitor cell migration.

We demonstrate the impact of a disrupted molecular clock in Bmal1-deficient (Bmal1-/-) mice on migration of neural progenitor cells (NPCs). Proliferation of NPCs in rostral migratory stream (RMS) was reduced in Bmal1-/- mice, consistent with our earlier studies on adult neurogenesis in hippocampus. However, a significantly higher number of NPCs from Bmal1-/- mice reached the olfactory bulb as compared to wild-type littermates (Bmal1+/+ mice), indicating a higher migration velocity in Bmal1-/- mice. In isolated NPCs from Bmal1-/- mice, not only migration velocity and expression pattern of genes involved in detoxification of reactive oxygen species were affected, but also RNA oxidation of catalase was increased and catalase protein levels were decreased. Bmal1+/+ migration phenotype could be restored by treatment with catalase, while treatment of NPCs from Bmal1+/+ mice with hydrogen peroxide mimicked Bmal1-/- migration phenotype. Thus, we conclude that Bmal1 deficiency affects NPC migration as a consequence of dysregulated detoxification of reactive oxygen species.