Adipose-Derived Mesenchymal Stromal Cells Under Hypoxia: Changes in Extracellular Vesicles Secretion and Improvement of Renal Recovery after Ischemic Injury.

BACKGROUND/AIMS: The therapeutic potential of extracellular vesicles (EVs) derived from mesenchymal stromal cells (MSCs) in kidney injury has been largely reported. However, new approaches are necessary to optimize the efficacy in the treatment of renal diseases. MSCs physiologically are under a low O2 partial pressure (pO2), and culturing adipose-derived MSCs (ADMSCs) in hypoxia alters their secretory paracrine properties. The aim of this study was to evaluate whether hypoxia preconditioning of ADMSCs alters the properties of secreted EVs to improve renal recovery after ischemia-reperfusion injury (IRI). METHODS: The supernatants of ADMSCs cultivated under 21% pO2 (control) or 1% pO2 (hypoxia) were ultracentrifuged for EVs isolation that were posteriorly characterized by flow cytometry and electron microscopy. The uptake and effects of these EVs were analyzed by using in vitro and in vivo models. HK-2 renal tubule cell line was submitted do ATP depletion injury model. Proteomic analyses of these cells treated with EVs after injury were performed by nano-UPLC tandem nano-ESI-HDMSE method. For in vivo analyses, male Wistar rats were submitted to 45 min bilateral ischemia, followed by renal intracapsular administration of ADMSC-EVs within a 72 h reperfusion period. Histological, immunohistochemical and qRT-PCR analysis of these kidneys were performed to evaluate cell death, inflammation and oxidative stress. Kidney function was evaluated by measuring the blood levels of creatinine and urea. RESULTS: The results demonstrate that hypoxia increases the ADMSCs capacity to secrete EVs that trigger different energy supply, antiapoptotic, immunomodulatory, angiogenic and anti-oxidative stress responses in renal tissue compared with EVs secreted in normoxia. Proteomic analyses of renal tubule cells treated with EVs from ADMSCs in normoxia and hypoxia give a specific signature of modulated proteins for each type of EVs, indicating regulation of distinct biological processes. CONCLUSION: In summary, hypoxia potentially offers an interesting strategy to enhance the properties of EVs in the treatment of acute kidney disease.

Corrigendum: Characterization of Aspergillus fumigatus Extracellular Vesicles and Their Effects on Macrophages and Neutrophils Functions.

[This corrects the article DOI: 10.3389/fmicb.2019.02008.].

Carrageenan hydrogel as a scaffold for skin-derived multipotent stromal cells delivery.

Carrageenan is a thermoreversible polymer of natural origin widely used in food and pharmaceutical industry that presents a glycosaminoglycan-like structure. Herein, we show that kappa-type carrageenan extracted by a semi-refined process from the red seaweed Kappaphycus alvarezii displayed both chemical and structural properties similar to a commercial carrageenan. Moreover, both extracted carrageenan hydrogel and commercial carrageenan hydrogel can serve as a scaffold for in vitro culture of human skin-derived multipotent stromal cells, demonstrating considerable potential as cell-carrier materials for cell delivery in tissue engineering. Skin-derived multipotent stromal cells cultured inside the carrageenan hydrogels showed a round shape morphology and maintained their growth and viability for at least one week in culture. Next, the effect of the extracted carrageenan hydrogel loaded with human skin-derived multipotent stromal cells was evaluated in a mouse model of full-thickness skin wound. Macroscopic and histological analyses revealed some pointed ameliorated features, such as reduced inflammatory process, faster initial recovery of wounded area, and improved extracellular matrix deposition. These results indicate that extracted carrageenan hydrogel can serve as a scaffold for in vitro growth and maintenance of human SD-MSCs, being also able to act as a delivery system of cells to wounded skin. Thus, evaluation of the properties discussed in this study contribute to a further understanding and specificities of the potential use of carrageenan hydrogel as a delivery system for several applications, further to skin wound healing.

Attachment of flagellum to the cell body is important to the kinetics of transferrin uptake by Trypanosoma cruzi.

The flagellar pocket and the cytostome are surface domains of Trypanosoma cruzi epimastigote involved in acquisition of nutrients. The cytostome is physically connected to the flagellar complex. To investigate if this association plays a role in endocytosis in T. cruzi, the endocytic activity in wild type and gp72 null mutant (flagellum-cell body attachment region is absent) epimastigotes was compared. Both wild type and mutant cells were incubated with transferrin conjugated with Alexa 543 or gold particles over different time periods and thereafter qualitatively and quantitatively analyzed by flow cytometry and transmission electron microscopy. Flow cytometry analysis showed a reduction in transferrin uptake by null mutant after 30 min of incubation. In addition, at this time period, signals detected by fluorescence microscopy were slightly lower in null mutant cells. At lower incubation times, no differences between wild type and mutant epimastigotes could be observed. Quantitative data obtained by morphometric and flow cytometry analysis suggested that the speed of the endocytic process in the null mutant was similar to wild type cells, although null mutants were not able to bind cargo and therefore internalize as much as wild type epimastigotes. Our observations suggest that the physical association between cytostome and the flagellar complex plays a role in endocytosis efficiency by epimastigotes of T. cruzi.