Extracellular matrix mimicking scaffold promotes osteogenic stem cell differentiation: A new approach in osteoporosis research.

BACKGROUND: Osteoporosis is a common metabolic disease, with mesenchymal stem cells discussed to play an important role in its pathomechanism. For in vitro osteoporosis studies, selection of adequate culture conditions is mandatory so as to preserve cell properties as far as possible. A suitable cell culture surface would ideally provide reproducible experimental conditions by resembling those in-vivo. OBJECTIVE: Generating an improved growth surface for osteogenic differentiation of human bone marrow derived mesenchymal stem cells (hBMSCs). METHODS: We modified electrospun gelatine meshes with hydroxyapatite nanopowder. The potential beneficial impact of the ensuing culture conditions were evaluated by cultivating and comparing the growth of cells from osteoporotic and non-osteoporotic donors on either hydroxyapatite-gelatine (HA) meshes, pure gelatine meshes, or 2D standard tissue culture surfaces. RESULTS: After 21 days of differentiation, cells grown on pure or HA-gelatine meshes showed significantly higher mineralization levels compared to cells cultured in standard conditions. The amount of mineralization varied considerably in hBMSC cultures of individual patients but showed no significant difference between stem cells obtained from osteoporotic or non-osteoporotic donors. CONCLUSIONS: Overall, these results indicate that the use of HA-gelatine meshes as growth surfaces may serve as a valuable tool for cultivation and differentiation of mesenchymal stem cells along the osteogenic lineage, facilitating future research on osteoporosis and related issues.

Time perception in patients with major depressive disorder during vagus nerve stimulation.

BACKGROUND: Affective disorders may affect patients' time perception. Several studies have described time as a function of the frontal lobe. The activating eff ects of vagus nerve stimulation on the frontal lobe might also modulate time perception in patients with major depressive disorder (MDD). METHODS: Time perception was investigated in 30 patients with MDD and in 7 patients with therapy-resistant MDD. In these 7 patients, a VNS system was implanted and time perception was assessed before and during stimulation. A time estimation task in which patients were asked "How many seconds have passed?" tested time perception at 4 defined time points (34 s, 77 s, 192 s and 230 s). The differences between the estimated and actual durations were calculated and used for subsequent analysis. RESULTS: Patients with MDD and healthy controls estimated the set time points relatively accurately. A general linear model revealed a significant main eff ect of group but not of age or sex. The passing of time was perceived as significantly slower in patients undergoing VNS compared to patients with MDD at all time points (T34: t = − 4.2; df = 35; p < 0.001; T77: t = − 4.8; df = 35; p < 0.001; T192: t = − 2.0; df = 35; p = 0.059; T230 t = −2.2; df = 35; p = 0.039) as well as compared to healthy controls (at only T77: t = 4.1; df = 35; p < 0.001). There were no differences in time perception with regard to age, sex or polarity of depression (uni- or bipolar). CONCLUSIONS: VNS is capable of changing the perception of time. This discovery furthers the basic research on circadian rhythms in patients with psychiatric disorders.