Raman spectroscopy of primary bovine aortic endothelial cells: a comparison of single cell and cell cluster analysis

Label-free detection of hydrogen peroxide-induced oxidative stress in human retinal pigment epithelium cells via laser tweezers Raman spectroscopy

Human retinal pigment epithelium cells under hydrogen peroxide-induced oxidative stress and a ligustrazine-based protective effect were investigated using laser tweezers Raman spectroscopy. Protein and lipid were significantly affected by oxidative damage, along with increased reactive oxygen species (ROS) level within cells. The effects of ligustrazine against the reaction of ROS with protein seemed to be able to inhibit such damages but were limited during the desamidization of amides, along with additional effect on nucleic acid base and DNA phosphoric acid skeleton. This work laid the basis for both understanding the molecular mechanisms of oxidative stress-induced injury and highlighting possible biomarkers in retinal diseases.

Label-free in vivo Raman microspectroscopic imaging of the macromolecular architecture of oocytes

Confocal Raman spectroscopy (CRS) can provide information about oocyte competency through measurement of changes in the macromolecular architecture during oocyte development and maturation. Hitherto most spectroscopic studies have been limited to fixed oocytes due to the inherent difficulties working with live cells. Here we report the first three-dimensional images of living murine oocytes using CRS. We show that fixation induces significant changes in the macromolecular chemistry compared to living oocytes. A band at 1602 cm⁻¹, assigned to a marker for mitochondria function was found in living oocytes but absent from fixed oocytes providing an in vivo marker. Fixation resulted in significant changes in protein and nucleic acid bands and the spatial distribution of organelles. Raman imaging of Metaphase I and II (MI, MII) and germinal vesicle stage oocytes showed changes in nuclear organisation and cytoplasm macromolecular architecture during these development and maturation stages related to changes in chromosome condensation, mitochondria aggregation and lipid droplet numbers.

Intracellular surface-enhanced Raman scattering probes based on TAT peptide-conjugated Au nanostars for distinguishing the differentiation of lung resident mesenchymal stem cells

Lung resident mesenchymal stem cells (LR-MSCs) are important regulators of pathophysiological processes including tissue repair and fibrosis, inflammation, angiogenesis and tumor formation. Therefore, increasing attention has focused on the functional differentiation of LR-MSCs. However, the distinction between the undifferentiated and differentiated LR-MSCs, which are closely related and morphologically similar, is difficult to achieve by conventional methods. In this study, by employing the TAT Peptide-conjugated Au nanostars (AuNSs) as an intracellular probe, we developed a method for the identification of LR-MSC differentiation by surface-enhanced Raman scattering (SERS) spectroscopy. SERS spectra were analyzed using principal component analysis (PCA) that allowed unambiguous distinction of subtypes and monitoring of component changes during cellular differentiation. Furthermore, to ascertain whether co-culture with alveolar epithelial type II (ATII) cells and incubation with transform growth factor (TGF)-β were involved in regulating the differentiation of LR-MSCs, we investigated the protein expression levels of epithelial markers and fibroblastic markers on LR-MSCs. Our results demonstrated that co-culture with ATII cells or incubation with TGF-β could induce the differentiation of LR-MSCs as confirmed by SERS analysis, a method that is capable of noninvasive characterization of and distinction between subtypes of LR-MSCs during differentiation. We have provided a new tool that may facilitate stem cell research.