Nitric Oxide Modulates Postnatal Bone Marrow-Derived Mesenchymal Stem Cell Migration

Transplantation of Bone Marrow Cells Preactivated With Sodium Nitroprusside Improves Acute Wound Healing in Rabbits

The development of wound healing impairment mainly represents challenging clinical problems. The less and high concentrations of nitric oxide can influence angiogenesis, remodeling, and proliferation of skin cells. Delayed acute wounds generally have failed to progress via the normal stages of healing. Such wounds usually enter a state of pathological inflammation due to a postponed, incomplete, and uncoordinated healing process. This study aimed to investigate the effect of normal bone marrow cells (BMCs) and preconditioning of BMCs with minimum concentrations of sodium nitroprusside (NaNP) solution for acute wound healing. For acute wound healing, full-thickness dorsal wounds were created on rabbits. The acute wound of rabbits was treated with BMCs and preactivated BMCs with NaNP. Histological results showed that BMCs preactivated with NaNP could improve collagen deposition, enhanced reepithelization, and decreased inflammatory infiltration. Overall, BMCs treated with NaNP can help to improve acute wound healing in rabbits. The result strongly confirmed the beneficial effect in augmenting the wound healing process. The combination of BMCs with NaNP was safe and convenient for acute wound healing.

The analysis of F-actin structure of mesenchymal stem cells by quantification of fractal dimension

The actin cytoskeleton is indispensable for the motility and migration of all types of cells; therefore, it plays a crucial role in the ability of the tissues to repair. Mesenchymal stem cells are intensively used in regenerative medicine, but usually relatively low percent of transplanted cells reaches the injury. To overcome this evident limitation, researchers try to enhance the motility and migration rate of the cells. As one of the approaches, co-cultivation and preconditioning of stem cells with biologically active compounds, which can cause actin cytoskeleton rearrangements followed by an increase of migratory properties of the cells, could be applied. The observed changes in F-actin structure induced by the compounds require quantitative estimation, and measurement of fluorescence intensity of the F-actin image captured by various microscopic techniques is commonly used nowadays. However, this approach could not always accurately detect the observed changes in the shape and structure of actin cytoskeleton. At this time, the image of F-actin has an irregular geometric pattern, and thus could be considered and characterized as a fractal object. To quantify the re-organization of cellular F-actin in terms of fractal geometry Minkovsky's box-counting method is suitable, but it is not widely used nowadays. We modified and improved the previously described method for fractal dimension measurement, and successfully applied it for the quantification of the F-actin structures of human mesenchymal stem cells.

A Photo-triggered and photo-calibrated nitric oxide donor: Rational design, spectral characterizations, and biological applications

Nitric oxide (NO) donors are valuable tools to probe the profound implications of NO in health and disease. The elusive nature of NO bio-relevance has largely limited the use of spontaneous NO donors and promoted the development of next generation NO donors, whose NO release is not only stimulated by a trigger, but also readily monitored via a judiciously built-in self-calibration mechanism. Light is without a doubt the most sensitive, versatile and biocompatible method of choice for both triggering and monitoring, for applications in complex biological matrices. Herein, we designed and synthesized an N-nitroso rhodamine derivative (NOD560) as a photo-triggered and photo-calibrated NO donor to address this need. NOD560 is essentially non-fluorescent. Upon irradiation by green light (532 nm), it efficiently release NO and a rhodamine dye, the dramatic fluorescence turn-on from which could be harnessed to conveniently monitor the localization, flux, and dose of NO release. The potentials of NOD560 for in vitro biological applications were also exemplified in in vitro biological models, i.e. mesenchymal stem cell (MSC) migration suppression. NOD560 is expected to complement the existing NO donors and find widespread applications in chemical biological studies.

Nitric oxide induces epidermal stem cell de-adhesion by targeting integrin β1 and Talin via the cGMP signalling pathway

OBJECTIVE

Nitric oxide (NO) has emerged as a critical molecule in wound healing, but the mechanism underlying its activity is not well defined. Here, we explored the effect of NO on the de-adhesion of epidermal stem cells (ESCs) and the mechanism involved in this process.

METHODS

The effects of NO on isolated human and mouse ESCs cultured in the presence of different concentrations of the NO donor S-nitroso-N-acetyl penicillamine (SNAP) were evaluated in cell de-adhesion assays mediated by integrin β and collagen IV. Subsequently, changes in the expression of integrin β1 and the phosphorylation of Talin in response to different doses of SNAP were detected by Western blot analysis and real-time PCR in vitro. Furthermore, the roles of various soluble guanylyl cyclase (sGC)- and protein kinase G (PKG)-specific inhibitors and agonists in the effects of NO on ESC de-adhesion, integrin β1 expression and Talin phosphorylation were analysed. Moreover, the effects of NO on integrin β1 expression and sGC/cGMP/PKG signalling-mediated wound healing were detected in vivo using 5-bromo-2-deoxyuridine (BrdU) label-retaining cells (LRCs) in a scald model and an excision wound healing model, respectively.

RESULTS

SNAP promoted primary human and mouse ESC de-adhesion in a concentration-dependent manner in the integrin β1-and collagen IV-mediated adhesion assay, and this effect was suppressed by the sGC and PKG inhibitors. Additionally, integrin β1 expression and Talin phosphorylation at serine 425 (S425) were negatively correlated with SNAP levels, and this effect was blocked by the sGC and PKG inhibitors. Moreover, the roles of NO in integrin β1 expression and cGMP signalling pathway-mediated wound healing were confirmed in vivo.

CONCLUSION

Our data indicate that the stimulatory effects of NO on ESC de-adhesion related to integrin β1 expression and Talin phosphorylation were mediated by the cGMP signalling pathway, which is likely involved in wound healing.

Human endogenous retrovirus W env increases nitric oxide production and enhances the migration ability of microglia by regulating the expression of inducible nitric oxide synthase

Human endogenous retrovirus W env (HERV-W env) plays a critical role in many neuropsychological diseases such as schizophrenia and multiple sclerosis (MS). These diseases are accompanied by immunological reactions in the central nervous system (CNS). Microglia are important immunocytes in brain inflammation that can produce a gasotransmitter-nitric oxide (NO). NO not only plays a role in the function of neuronal cells but also participates in the pathogenesis of various neuropsychological diseases. In this study, we reported increased NO production in CHME-5 microglia cells after they were transfected with HERV-W env. Moreover, HERV-W env increased the expression and function of human inducible nitric oxide synthase (hiNOS) and enhanced the promoter activity of hiNOS. Microglial migration was also enhanced. These data revealed that HERV-W env might contribute to increase NO production and microglial migration ability in neuropsychological disorders by regulating the expression of inducible NOS. Results from this study might lead to the identification of novel targets for the treatment of neuropsychological diseases, including neuroinflammatory diseases, stroke, and neurodegenerative diseases.