BackgroundThe rapid increase in carbon black poses threats to human health. We evaluated the effect of CB (Printex 90) on the osteogenesis of bone-marrow-derived mesenchymal stem cells (MSCs). Mitochondria play an important role in the osteogenesis of MSCs and are potential targets of nanomaterials, so we studied the role of mitochondria in the CB Printex 90-induced effects on osteogenesis.ResultsLow doses of Printex 90 (3 ng/mL and 30 ng/mL) that did not cause deleterious effects on MSCs’ viability significantly inhibited osteogenesis of MSCs. Printex 90 caused down-regulation of osteoblastic markers, reduced activity of alkaline phosphatase (ALP), and poor mineralization of osteogenically induced MSCs. Cellular ATP production was decreased, mitochondrial respiration was impaired with reduced expression of ATPase, and the mitochondrial membrane was depolarized. The quantity and quality of mitochondria are tightly controlled by mitochondrial biogenesis, mitochondrial dynamics and mitophagy. The transcriptional co-activator and transcription factors for mitochondrial biogenesis, PGC-1α, Nrf1 and TFAM, were suppressed by Printex 90 treatment, suggesting that decreased biogenesis was caused by Printex 90 treatment during osteogenesis. Mitochondrial fusion and fission were significantly inhibited by Printex 90 treatment. PINK1 accumulated in Printex 90-treated cells, and more Parkin was recruited to mitochondria, indicating that mitophagy increased to remove the damaged mitochondria.ConclusionsThis is the first report of the inhibitory effects of CB on the osteogenesis of MSCs and the involvement of mitochondria in CB Printex 90-induced suppression of MSC osteogenesis.Electronic supplementary materialThe online version of this article (10.1186/s12989-018-0253-5) contains supplementary material, which is available to authorized users.

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Energy consumption in commercial buildings is tremendous, resulting in significant monetary cost and waste of natural resources. Designing a low-cost system that serves the goal of saving energy while not forcing people to compromise their personal comfort is important for future smart commercial buildings. Proactive energy saving actions from users in the buildings are the key to achieving this goal. In this paper, we present Mahalo, an energy saving system, which leverages users through social gaming. By incentivizing energy saving actions from end users with a sensing-based feedback control system, the system reduces installation needs and improves understanding of the users preferences.

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