H2O2-preconditioned human adipose-derived stem cells (HC016) increase their resistance to oxidative stress by overexpressing Nrf2 and bioenergetic adaptation.

BACKGROUND: Mesenchymal stem cells, including those derived from human adipose tissue (hASCs), are currently being widely investigated for cell therapy. However, when transplanted at the site of injury, the survival and engraftment rates of hASCs are low, mainly due to the harsh microenvironment they encounter, characterized by inflammation and oxidative stress. To overcome these therapeutic limitations, cell preconditioning with low-concentration of hydrogen peroxide (H2O2) has been proposed as a plausible strategy to increase their survival and adaptation to oxidative stress. Nonetheless, the underlying mechanisms of this approach are not yet fully understood. In this study, we analyzed molecular and bioenergetic changes that take place in H2O2 preconditioned hASCs. METHODS: Long-term exposure to a low concentration of H2O2 was applied to obtain preconditioned hASCs (named HC016), and then, their response to oxidative stress was analyzed. The effect of preconditioning on the expression of Nrf2 and its downstream antioxidant enzymes (HO-1, SOD-1, GPx-1, and CAT), and of NF-κB and its related inflammatory proteins (COX-2 and IL-1ß), were examined by Western blot. Finally, the Seahorse XF96 Flux analysis system was used to evaluate the mitochondrial respiration and glycolytic function, along with the total ATP production. RESULTS: We found that under oxidative conditions, HC016 cells increased the survival by (i) decreasing intracellular ROS levels through the overexpression of the transcription factor Nrf2 and its related antioxidant enzymes HO-1, SOD-1, GPx-1, and CAT; (ii) reducing the secretion of pro-inflammatory molecules COX-2 and IL-1ß through the attenuation of the expression of NF-κB; and (iii) increasing the total ATP production rate through the adaption of their metabolism to meet the energetic demand required to survive. CONCLUSIONS: H2O2 preconditioning enhances hASC survival under oxidative stress conditions by stimulating their antioxidant response and bioenergetic adaptation. Therefore, this preconditioning strategy might be considered an excellent tool for strengthening the resistance of hASCs to harmful oxidative stress.

The Neuroprotective Effect of Conditioned Medium from Human Adipose-Derived Mesenchymal Stem Cells is Impaired by N-acetyl Cysteine Supplementation.

Oxidative stress is a common feature in neurodegenerative diseases associated with neuroinflammation, and therefore, has been proposed as a key target for novel therapies for these diseases. Recently, adipose-derived stem cell (ASC)-based cell therapy has emerged as a novel strategy for neuroprotection. In this study, we evaluate the therapeutic role of ASC-conditioned medium (ASC-CM) against H2O2-induced neurotoxicity in a new in vitro model of ec23/brain-derived neurotrophic factor (BDNF)-differentiated human SH-SY5Y neuron-like cells (SH-SY5Yd). In the presence of ASC-CM, stressed SH-SY5Yd cells recover normal axonal morphology (with an almost complete absence of H2O2-induced axonal beading), electrophysiological features, and cell viability. This beneficial effect of ASC-CM was associated with its antioxidant capacity and the presence of growth factors, namely, BDNF, glial cell line-derived neurotrophic factor, and transforming growth factor ß1. Moreover, the neuroprotective effect of ASC-CM was very similar to that obtained from treatment with BDNF, an essential factor for SH-SY5Yd cell survival. Importantly, we also found that the addition of the antioxidant agent N-acetyl cysteine to ASC-CM abolished its restorative effect; this was associated with a strong reduction in reactive oxygen species (ROS), in contrast to the moderate decrease in ROS produced by ASC-CM alone. These results suggest that neuronal restorative effect of ASC-CM is associated with not only the release of essential neurotrophic factors, but also the maintenance of an appropriate redox state to preserve neuronal function.

Development and preclinical evaluation of a new galactomannan-based dressing with antioxidant properties for wound healing.

We describe a novel wound dressing (HR006) with two components: a lyophilized matrix of the galactomannan from locust bean gum (LBG) and an antioxidant hydration solution (AHsol) containing curcumin and N-acetyl-L-cysteine (NAC). Physico-structural analyses of the LBG matrix revealed homogeneous interconnected pores with high absorbing capacity showing excellent properties for moist wound care (MWC). In an in vitro oxidative stress fibroblast injury model, the AHsol showed relevant protective effects reducing intracellular reactive oxygen species (ROS) production, rescuing cell viability, and regulating expression of inflammation-related genes (COX-2, TNF-α, IL-1α, IL-1ß). The new dressing showed good biocompatibility profile as demonstrated by cytotoxicity, hemocompatibility, and skin irritation tests. Moreover, in an in vivo skin wound model in pigs, this dressing enhanced the production of healthy and organized granulation tissue and re-epithelization. In summary, HR006 exhibits significant antioxidant activity, good biocompatibility, and excellent repair capabilities improving tissue remodeling and the healing of wounds.

Effect of bioactive glass particles on osteogenic differentiation of adipose-derived mesenchymal stem cells seeded on lactide and caprolactone based scaffolds.

Incorporation of bioactive glass (BG) particles to synthetic polymer scaffolds is a promising strategy to improve the bioactivity of bioinert materials and to stimulate specific cell responses. In this study, the influence of incorporating BG particles to lactide and caprolactone based porous scaffolds on osteogenic differentiation of adipose-derived stem cells (ASCs) was analyzed. Accordingly, ASCs were seeded on poly(L-lactide) (PLLA), poly(ε-caprolactone) (PCL), or poly(L-lactide-co-ε-caprolactone) (PLCL) scaffolds containing 15 vol % of BG particles in two culture conditions: standard versus osteogenic culture medium. In standard culture medium, incorporation of BG to a PLLA scaffold increased the ALP activity with respect to its unfilled counterpart (ca. 1.2- and a 1.6-fold increase over 7 and 14 days, respectively). Moreover, in all the studied polymers the incorporation of BG induced a slightly higher production of mineralized matrix by ASCs, but the differences observed were not statistically significant. In the osteogenic medium, the effect of BG was masked by the effect of osteogenic supplements in the long-term. However, in the short-term (day 7), BG particles induced an early ALP activity of predifferentiated osteoblasts on PLLA and PCL scaffolds and higher matrix mineralization on PCL scaffolds. In summary, the addition of BG particles to PLLA and PCL scaffolds sustains ASC osteogenic differentiation, facilitates mineralization and induces the formation of a hydroxyapatite layer on the surface of the polymer scaffolds.