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Compartment specific changes of the antioxidative status in Arabidopsis thaliana during salt stress
Barbara Eva Koffler,Nora Luschin-Ebengreuth,Bernd Zechmann 한국식물학회 2015 Journal of Plant Biology Vol.58 No.1
The compartment specific importance of ascorbate and glutathione was investigated during salt stress in Arabidopsis Col-0 and mutants deficient in ascorbate and glutathione (vtc2–1, pad2–1). This study demonstrated that higher sensitivity of the vtc2–1 mutants which showed leaf necrosis and lower biomass at the beginning of the salt stress experiment was correlated with lower basal ascorbate contents and a decrease in ascorbate contents in mitochondria (67%), peroxisomes (68%) and the cytosol (38%). Higher tolerance of pad2–1 mutants to salt stress throughout the first 10 days of the experiment could be correlated to a massive increase of glutathione contents (up to 740% in nuclei) in all cell compartments. A similar situation was found for wildtype plants which showed higher tolerance to salt stress at the beginning of the experiment which could be correlated with a strong increase of glutathione contents in mitochondria (39%), chloroplasts (up to 26%) and peroxisomes (up to 84%) indicating an important role of glutathione in the protection of these cell compartments against salt stress. Summing up, the results demonstrate that higher tolerance to salt stress of wildtype plants and pad2–1 mutants at the beginning of the experiment could be correlated to increased glutathione contents which could not be found in vtc2–1 mutants which in addition showed lower ascorbate contents and higher sensitivity to salt stress.
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Electroconductive PEDOT nanoparticle integrated scaffolds for spinal cord tissue repair
Aleksandra Serafin,Mario Culebras Rubio,Marta Carsi,Pilar Ortiz-Serna,Maria J. Sanchis,Atul K. Garg,J. Miguel Oliveira,Jacob Koffler,Maurice N. Collins 한국생체재료학회 2022 생체재료학회지 Vol.26 No.4
Background: Hostile environment around the lesion site following spinal cord injury (SCI) prevents the re-establishment of neuronal tracks, thus significantly limiting the regenerative capability. Electroconductive scaffolds are emerging as a promising option for SCI repair, though currently available conductive polymers such as polymer poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) present poor biofunctionality and biocompatibility, thus limiting their effective use in SCI tissue engineering (TE) treatment strategies. Methods: PEDOT NPs were synthesized via chemical oxidation polymerization in miniemulsion. The conductive PEDOT NPs were incorporated with gelatin and hyaluronic acid (HA) to create gel:HA:PEDOT-NPs scaffolds. Morphological analysis of both PEDOT NPs and scaffolds was conducted via SEM. Further characterisation ncluded dielectric constant and permittivity variances mapped against morphological changes after crosslinking, Young’s modulus, FTIR, DLS, swelling studies, rheology, in-vitro, and in-vivo biocompatibility studies were also conducted. Results: Incorporation of PEDOT NPs increased the conductivity of scaffolds to 8.3 × 10–4± 8.1 × 10–5 S/cm. The compressive modulus of the scaffold was tailored to match the native spinal cord at 1.2 ± 0.2 MPa, along with controlled porosity. Rheological studies of the hydrogel showed excellent 3D shear-thinning printing capabilities and shape fidelity post-printing. In-vitro studies showed the scaffolds are cytocompatible and an in-vivo assessment in a rat SCI lesion model shows glial fibrillary acidic protein (GFAP) upregulation not directly in contact with the lesion/implantation site, with diminished astrocyte reactivity. Decreased levels of macrophage and microglia reactivity at the implant site is also observed. This positively influences the re-establishment of signals and initiation of healing mechanisms. Observation of axon migration towards the scaffold can be attributed to immunomodulatory properties of HA in the scaffold caused by a controlled inflammatory response. HA limits astrocyte activation through its CD44 receptors and therefore limits scar formation. This allows for a superior axonal migration and growth towards the targeted implantation site through the provision of a stimulating microenvironment for regeneration. Conclusions: Based on these results, the incorporation of PEDOT NPs into Gel:HA biomaterial scaffolds enhances not only the conductive capabilities of the material, but also the provision of a healing environment around lesions in SCI. Hence, gel:HA:PEDOT-NPs scaffolds are a promising TE option for stimulating regeneration for SCI.
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