ISEL - Eng. Quim. Biol. - Comunicações
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Browsing ISEL - Eng. Quim. Biol. - Comunicações by Author "Aleixo, Sandra"
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- Evaluating the impact of culture conditions on human mesenchymal stromal cell-derived extracellular vesicles molecular fingerprint through FTIR spectroscopyPublication . Fernandes, Ana; Pereira, Maria; Ramalhete, Luís; Aleixo, Sandra; Silva, Cláudia; Cabral, Joaquim M.S.; Calado, CecíliaThis work is a step forward into understanding how different culture conditions affect MSC-derived EVs characteristics.
- Impact of the human mesenchymal stem cells donor on conditional medium compositionPublication . Pereira, Maria João Canha; Ramalhete, Luís; Aleixo, Sandra; da Silva, Cláudia L.; Cabral, Joaquim M.S.; Calado, Cecília; Fernandes, AnaExosomes produced by Mesenchymal Stem Cells (MSCs) can represent a very appealing strategy for cell-free therapies. However, to achieve this reality it is necessary to further understand the process associated to the MSC culture when conditioned to produce exosomes. In the present work, it was evaluated how different MSC obtained from different donors may affect the conditioned media composition and how this can be influenced by the conditioned media type (DMEM versus Xeno-Free medium, XF). The molecular fingerprint of the conditioned media composition was obtained by mid-infrared (MIR) spectroscopy, as this technique reflects fundamental vibrations of a high diversity of functional chemical groups present in biological samples. It was observed by principal component analysis of the second derivative spectra of conditioned media that the media chemical composition depends more from the MSCs donor than the conditioning days. Diverse spectral regions, characteristic of defined chemical groups, enabled to discriminate the chemical composition of the media according to the MSC donor. All of this was observed in both types of media (DMEM and XF). This work is a step forward to understand how different MSC donors and conditioned media may affect the exosomes characteristics.
- Towards an automated statistical workflow for biomarker screening in Fourier-transform infrared spectroscopyPublication . Ribeiro Da Cunha, Bernardo; Aleixo, Sandra; Fonseca, Luís P.; Calado, CecíliaThe increasing availability and sensitivity of analytical technologies has resulted in much higher complexity of molecular and cellular data, which biomarkers facilitate the bridge with a given biological state under scrutiny. Importantly, biomarkers are critical in spectroscopic technologies, as is the case of Fourier-transform infrared spectroscopy, for which different approaches to identify biomarkers have been established, for instance univariate statistical hypothesis tests. A workflow for the automatic application of said statistical tests is proposed with the objective of enabling a high throughput screening-approach that ensures statistical robustness, and works in a user-independent manner, thereby reducing analysis bias. The proposed workflow is the first step towards an automated method for biomarker screening, thus it is limited to distinguishing two populations. Firstly, the method used in previous work was improved to ensure the most powerful and accurate statistical tests are applied. Then, the statistical workflow was generalized to a more comprehensive range of data sets of two populations, for instance when sample size is not deemed high (less than thirty observations). Lastly, future work is outlined regarding the extension of the workflow to cases with more than two populations, but also of methods that can increase the pool of putative biomarkers that will then be screened for statistical significance.