Nuclear magnetic resonance footprint of Wharton Jelly mesenchymal stem cells death mechanisms and distinctive in-cell biophysical properties in vitro.

The importance of the biophysical characterization of mesenchymal stem cells (MSCs) was recently pointed out for supporting the development of MSC-based therapies. Among others, tracking MSCs in vivo and a quantitative characterization of their regenerative impact by nuclear magnetic resonance (NMR) demands a full description of MSCs' MR properties. In the work, Wharton Jelly MSCs are characterized in a low magnetic field (LF) in vitro by using different approaches. They encompass various settings: MSCs cultured in a Petri dish and cell suspensions; experiments- 1D-T 1 , 1D-T 2 , 1D diffusion, 2D T 1 -T 2 and D-T 2 ; devices- with a bore aperture and single-sided one. Complex NMR analysis with the aid of random walk simulations allows the determination of MSCs T 1 and T 2 relaxation times, cells and nuclei sizes, self-diffusion coefficients of the nucleus and cytoplasm. In addition, the influence of a single layer of cells on the effective diffusion coefficient of water is detected with the application of a single-sided NMR device. It also enables the identification of apoptotic and necrotic cell death and changed diffusional properties of cells suspension caused by compressing forces induced by the subsequent cell layers. The study delivers MSCs-specific MR parameters that may help tracking MSCs in vivo.

Low-field 1H NMR parameterization of model cell suspensions. A diffusion and relaxation study.

Introduction: Nuclear magnetic resonance (NMR) is a powerful method for the non-invasive study of a wide range of objects. Among its many characteristics, molecular diffusion can be examined without the need for any chemical or isotopic tracers by applying magnetic field gradients within the NMR sequence. Aim: In our study, model cell suspensions were characterized by means of low-field (LF) (0.05 T) 1H NMR relaxometry. The proposed multi-parametric characterization based on independent 2D T1-T2 and D-T2 measurements was implemented to obtain a set of MR parameters as a specific signature for model cells. Material and methods: The D-T2 and T1-T2 correlation measurements were conducted on yeast samples with different amounts of added water. Signals from intracellular and extracellular water compartments and free water were identified on D-T2 maps and their diffusion coefficients were extracted. Results: Mean D_IC was equal to 8.4 × 10-11 m2/s and mean D_EC ranged from 1.0 × 10-9 m2/s to 1.65 × 10-9 m2/s. T1/T2 ratio was calculated and for IC space values in the range of 4.2-5.3 were observed. Finally, we demonstrated the possibility of detecting signals from cells for the samples with a low concentration of cell suspensions or a small amount of the sample. Conclusions: These findings are promising for more complex cell investigations in vitro and in vivo, without any contrast agents, applying solely biomarkers.

Water Interactions in Hybrid Polyacrylate-Silicate Hydrogel Systems.

Hybrid polyacrylate-silicate hydrogels were obtained in the presence of N,N'-methylenebisacrylamide (NNMBA) as the cross-linking monomer and sodium thiosulphate/potassium persulphate (NTS/KPS) as the redox initiators. The results of the tests allowed us to conclude that a hybrid structure with a polyacrylate scaffolding and a silicate matrix had been obtained. The results of the rheological analysis revealed that the hydrogel sample with a 1:7 mass ratio of sodium water glass to the sodium polyacrylate is characterized by the highest complex viscosity. Thermal analysis (Thermogravimetry/Differential Scanning Calorimetry (TG/DSC)) showed that water begins to evaporate at higher temperatures, from 120 °C to even 180 °C. These results were confirmed by mid-infrared spectroscopy (MIR) and nuclear magnetic resonance spectroscopy (NMR) analysis. Differences in the intensity of the peaks derived from water in the MIR spectra indicate that most of the water is bounded. In turn, NMR results showed that the mobility of water molecules decreases as the amount of sodium water glass in the mixture increases.