Search results for "Oxygen tension"
showing 10 items of 37 documents
Importance of stem cell culture conditions for their derived extracellular vesicles therapeutic effect.
2021
Stem cell-derived extracellular vesicles (EVs) could be enhanced by modifying specific in vitro parameters when culturing their originating stem cells. Controlling stem cell growth conditions with physical properties, oxygen tension and media preconditioning with soluble factors may influence EVs biogenesis and EVs biological function as well. Unfortunately, many misconceptions and methodological issues have hampered the progress in understanding the biological properties of EVs. In this review we will first discuss the major concerns involved in a suitable EVs production from stem cell culture. Then, we will describe the current techniques for EV isolation, focusing on their advantages and…
Lack of correlation between expression of HIF-1alpha protein and oxygenation status in identical tissue areas of squamous cell carcinomas of the uter…
2004
Abstract Hypoxia inducible factor-1α (HIF-1α) has been proposed as a candidate endogenous marker of tumor hypoxia and as a molecular mediator of hypoxia-driven malignant progression and acquired treatment resistance. In this study, HIF-1α expression in 68 biopsies of oxygenation measurement tracks from squamous cell carcinomas of the uterine cervix of 38 patients was assessed. Expression of HIF-1α was commonly found to increase as a function of distance from microvessels, at the center of tumor cell aggregations, and in the vicinity of necrotic areas. However, there was no correlation of HIF-1α expression with median oxygen tension (oxygen partial pressure; pO2) and hypoxic fractions (hypox…
Extracellular Vesicles from Healthy Cells Improves Cell Function and Stemness in Premature Senescent Stem Cells by miR-302b and HIF-1α Activation.
2020
Aging is accompanied by the accumulation of senescent cells that alter intercellular communication, thereby impairing tissue homeostasis and reducing organ regenerative potential. Recently, the administration of mesenchymal stem cells (MSC)-derived extracellular vesicles has proven to be more effective and less challenging than current stem cell-based therapies. Extracellular vesicles (EVs) contain a cell-specific cargo of proteins, lipids and nucleic acids that are released and taken up by probably all cell types, thereby inducing functional changes via the horizontal transfer of their cargo. Here, we describe the beneficial properties of extracellular vesicles derived from non-senescent M…
Role of p16INK4a and BMI-1 in oxidative stress-induced premature senescence in human dental pulp stem cells
2017
Human dental pulp stem cells (hDPSCs) are a source for cell therapy. Before implantation, an in vitro expansion step is necessary, with the inconvenience that hDPSCs undergo senescence following a certain number of passages, loosing their stemness properties. Long-term in vitro culture of hDPSCs at 21% (ambient oxygen tension) compared with 3–6% oxygen tension (physiological oxygen tension) caused an oxidative stress-related premature senescence, as evidenced by increased β-galactosidase activity and increased lysil oxidase expression, which is mediated by p16INK4a pathway. Furthermore, hDPSCs cultured at 21% oxygen tension underwent a downregulation of OCT4, SOX2, KLF4 and c-MYC factors, w…
Biological response of multicellular emt6 spheroids to exogenous lactate
1991
The influence of elevated lactate concentrations, as found in tumor microregions, on cellular growth, viability, and metabolic state was studied employing the multicellular spheroid model. Spheroids of EMT6/Ro cells were cultured at 37 degrees C in 5% or 20% (v/v) oxygen, using stirred media with various concentrations of exogenous lactate ranging from 0.0 mM (standard conditions) to 20.0 mM. Elevated concentrations of exogenous lactate led to a considerable decrease of the maximum spheroid diameter at growth saturation, e.g., for 20% O2 from around 1700 microns to 700 microns in 0.0 and 20.0 mM lactate respectively. Histological investigations showed that the thickness of the viable cell r…
Calibration of misonidazole labeling by simultaneous measurement of oxygen tension and labeling density in multicellular spheroids
1995
To correlate misonidazole concentrations and oxygen pressures (Po2) at identical locations within EMT6/Ro multi-cell spheroids (mean diameters +/- SD: 867 +/- 20 microns), Po2 measurements were performed with oxygen-sensitive microelectrodes during incubation of these spheroids with tritiated misonidazole (10 mg/I; 445 microCi/mg). In each individual spheroid, Po2 profiles were correlated with the corresponding spatial distribution of misonidazole as quantified by conventional autoradiography and grain counting. To compare the oxygenation status of spheroids in the measuring chamber with that of spheroids in spinner culture, misonidazole labeling was performed in both environments following…
Tissue gradients of energy metabolites mirror oxygen tension gradients in a rat mammary carcinoma model
2001
Abstract Purpose: It has been shown that oxygen gradients exist in R3230AC tumors grown in window chambers. The fascial surface is better oxygenated than the tumor surface. The purpose of the present study was to determine whether gradients exist for energy metabolites and other end points related to oxygen transport. Methods and Materials: Imaging bioluminescence was used to measure ATP, glucose, and lactate in cryosections of R3230AC tumors. Mean vessel density and hypoxic tissue fraction were assessed using immunohistochemistry. Tumor redox ratio was assessed by redox ratio scanning. Results: Lactate content and hypoxic fraction increased, whereas ATP, glucose, redox ratio, and vessel de…
Effect of Supplemental Oxygen versus Dobutamine Administration on Liver Oxygen Tension in dPP-Guided Normovolemic Pigs
2008
<i>Background:</i> Difference in pulse pressure (dPP) confirms adequate intravascular filling as a prerequisite for tissue perfusion. We hypothesized that both oxygen and dobutamine increase liver tissue oxygen tension (pt<i>O</i><sub>2</sub>). <i>Methods:</i> Eight anesthetized pigs received dPP-guided fluid management. Hepatic p<i>O</i><sub>2</sub> was measured with Clark-type electrodes placed subcapsularly, and on the liver surface. Pigs received: (1) supplemental oxygen (F<sub>i</sub><i>O</i><sub>2</sub> 1.0); (2) dobutamine 2.5 μg/kg/min, and (3) dobutamine 5 μg/kg/min. Data wer…
Ceramide Mediates Acute Oxygen Sensing in Vascular Tissues
2014
AbstractAims: A variety of vessels, such as resistance pulmonary arteries (PA) and fetoplacental arteries and the ductus arteriosus (DA) are specialized in sensing and responding to changes in oxygen tension. Despite opposite stimuli, normoxic DA contraction and hypoxic fetoplacental and PA vasoconstriction share some mechanistic features. Activation of neutral sphingomyelinase (nSMase) and subsequent ceramide production has been involved in hypoxic pulmonary vasoconstriction (HPV). Herein we aimed to study the possible role of nSMase-derived ceramide as a common factor in the acute oxygen-sensing function of specialized vascular tissues. Results: The nSMase inhibitor GW4869 and an anticera…
Geometric Considerations in Modeling Oxygen Transport Processes in Tissue
1973
Numerical solution of partial differential equations describing transport processes in capillaries and tissue is used for calculation of oxygen transport to brain tissue. Calculation is based on a three-dimensional network model which covers inhomogeneities in capillary blood flow in a relation of 27:1, This study was performed in order to obtain information about the influence of the main physiological parameters on oxygen tension frequency distribution pattern. Following results were obtained: a)Increase (or decrease) of the oxygen consumption rate in tissue to about twice (or half) of the normal case for cerebral grey matter causes an extreme left (or right) shift of the oxygen tension f…