Discrimination of functional hepatocytes derived from mesenchymal stem cells using FTIR microspectroscopy

Evaluation of induced pluripotent stem cell differentiation into neural progenitor cell using Raman spectra derived from extracellular vesicles in culture supernatants

Non-invasive cell culture monitoring technology is crucial to improve the manufacturing efficiency of cell products. We have found that extracellular vesicles (EVs) are secreted into the culture supernatants in the differentiation process from human induced pluripotent stem cells (iPSCs) to dopaminergic progenitor cells, and that the composition of EVs changes in accordance with the differentiation processes. In this study, we hypothesized that it is possible to evaluate the cultured cellular states by detecting compositional changes of EVs secreted from cultured cells with label-free Raman spectroscopy in a non-invasive manner. Therefore, Raman signal analysis derived from EV fractions isolated from culture supernatants throughout the differentiation process was conducted. iPSCs cultures were simultaneously implemented under a standard condition (control) and an artificial deviation condition inducing reductions in pluripotency by depleting FGF2 in culture medium (-FGF2), which is indispensable for maintaining the pluripotency. Subsequently, the differentiation step was conducted for each iPSCs culture under the same condition. As a result, it was found that under -FGF2, the expression level of the pluripotency marker NANOG decreased compared to that of the control and correlated with the identification results based on Raman signals with a correlation coefficient of 0.77. Lipid-derived Raman signals were extracted as identification factors, suggesting that changes in the lipid component of EV occur depending on the cellular states. From the above, we have found that the change in composition of EVs in the culture supernatant by detecting Raman signals would be a monitoring index of the cellular state of differentiation and pluripotency.

AFM Study of Nanoscale Membrane Perturbation Induced by Antimicrobial Lipopeptide C14 KYR

Lipopeptides have been extensively studied as potential antimicrobial agents. In this study, we focused on the C₁₄-KYR lipopeptide, a modified version of the KYR tripeptide with myristic acid at the N-terminus. Here, membrane perturbation of live E. coli treated with the parent KYR and C₁₄-KYR peptides was compared at the nanoscale level using AFM imaging. AFM analyses, including average cellular roughness and force spectroscopy, revealed the severe surface disruption mechanism of C₁₄-KYR. A loss of surface roughness and changes in topographic features included membrane shrinkage, periplasmic membrane separation from the cell wall, and cytosolic leakage. Additional evidence from synchrotron radiation FTIR microspectroscopy (SR-FTIR) revealed a marked structural change in the membrane component after lipopeptide attack. The average roughness of the E. coli cell before and after treatment with C₁₄-KYR was 129.2 ± 51.4 and 223.5 ± 14.1 nm, respectively. The average rupture force of the cell treated with C₁₄-KYR was 0.16 nN, four times higher than that of the untreated cell. Our study demonstrates that the mechanistic effect of the lipopeptide against bacterial cells can be quantified through surface imaging and adhesion force using AFM.

Reversal of Experimental Liver Damage after Transplantation of Stem-Derived Cells Detected by FTIR Spectroscopy

The transplantation of autologous BM-MSCs holds great potential for treating end-stage liver diseases. The aim of this study was to compare the efficiency of transplanted rBM-MSCs and rBM-MSC-derived differentiated stem cells (rBM-MSC-DSCs) for suppression of dimethylnitrosamine-injured liver damage in rat model. Synchrotron radiation Fourier-transform infrared (SR-FTIR) microspectroscopy was applied to investigate changes in the macromolecular composition. Transplantation of rBM-MSC-DSCs into liver-injured rats restored their serum albumin level and significantly suppressed transaminase activity as well as the morphological manifestations of liver disease. The regenerative effects of rBM-MSC-DSCs were corroborated unequivocally by the phenotypic difference analysis between liver tissues revealed by infrared spectroscopy. Spectroscopic changes in the spectral region from 1190–970 cm⁻¹ (bands with absorbance maxima at 1150 cm⁻¹, 1081 cm⁻¹, and 1026 cm⁻¹) indicated decreased levels of carbohydrates, in rBM-MSC-DSC-transplanted livers, compared with untreated and rBM-MSC--transplanted animals. Principal component analysis (PCA) of spectra acquired from liver tissue could readily discriminate rBM-MSC-DSC-transplanted animals from the untreated and rBM-MSC-transplanted animals. We conclude that the transplantation of rBM-MSC-DSCs effectively treats liver disease in rats and SR-FTIR microspectroscopy provides important insights into the fundamental biochemical alterations induced by the stem-derived cell transplantation, including an objective “signature” of the regenerative effects of stem cell therapy upon liver injury.

Effect of Chromatin-Remodeling Agents in Hepatic Differentiation of Rat Bone Marrow-Derived Mesenchymal Stem Cells In Vitro and In Vivo

Epigenetic events, including covalent histone modifications and DNA methylation, play fundamental roles in the determination of lineage-specific gene expression and cell fates. The aim of this study was to determine whether the DNA methyltransferase inhibitor (DNMTi) 5-aza-2′-deoxycytidine (5-aza-dC) and the histone deacetylase inhibitor (HDACi) trichostatin A (TSA) promote the hepatic differentiation of rat bone marrow-derived mesenchymal stem cells (rBM-MSCs) and their therapeutic effect on liver damage. 1 μM TSA and 20 μM 5-aza-dC were added to standard hepatogenic medium especially at differentiation and maturation steps and their potential function on hepatic differentiation in vitro and in vivo was determined. Exposure of rBM-MSCs to 1 μM TSA at both the differentiation and maturation steps considerably improved hepatic differentiation. TSA enhanced the development of the hepatocyte shape, promoted the chronological expression of hepatocyte-specific markers, and improved hepatic functions. In contrast, treatment of rBM-MSCs with 20 μM 5-aza-dC alone or in combination with TSA was ineffective in improving hepatic differentiation in vitro. TSA and/or 5-aza-dC derived hepatocytes-like cells failed to improve the therapeutic potential in liver damage. We conclude that HDACis enhance hepatic differentiation in a time-dependent manner, while DNMTis do not induce the hepatic differentiation of rBM-MSCs in vitro. Their in vivo function needs further investigation.

Plasma biomarkers of pulmonary hypertension identified by Fourier transform infrared spectroscopy and principal component analysis

The main goal of this study was to find specific plasma spectral markers associated with pulmonary arterial hypertension (PAH) induced by monocrotaline injection in rats. FTIR was used to monitor biochemical changes in plasma caused by PAH as compared with the systemic hypertension induced by partial ligation on the left artery and with the control group. Both pathologies, systemic and pulmonary hypertension, induced a unique response in the biochemical content of plasma, mainly related to the composition and secondary structure of plasma proteins. For PAH, β-pleated sheet components of plasma proteins were identified whereas the protein composition in systemic hypertension was dominated by unordered structures. In addition, a higher concentration of tyrosine-rich proteins was found in plasma in PAH than in systemic hypertension. The differences between both pathologies were identified also in terms of lipid composition/metabolism as well as in the content of RNA and glucose, suggesting that lipid peroxidation appears upon pulmonary hypertension development. In summary, this work demonstrates that FTIR spectroscopy supported by principal component analysis (PCA) has the potential to become a fast and non-destructive method for biochemical characterization of plasma that consequently could have a diagnostic significance in pulmonary hypertension.

Melatonin induces apoptosis through biomolecular changes, in SK-LU-1 human lung adenocarcinoma cells

OBJECTIVES

Anti-cancer effects of melatonin (N-acetyl-5-methoxytryptamine, an indole-amine), have been widely reported, however, little has been known, regarding its mechanism(s) of action in lung cancer. Thus, we investigated its induction of apoptosis through biomolecular changes (lipid, protein and nucleic acid/DNA) in the SK-LU-1 human lung cancer cell line.

MATERIALS AND METHODS

We used Fourier transform infrared (FTIR) microspectroscopy, and conventional methods, to confirm changes in lipid (annexin V/PI staining for membrane alteration), protein (caspase-3/7 protein activity) and DNA (DAPI staining for DNA fragmentation).

RESULTS

We observed from FTIR data that melatonin increased lipid content and reduced intensity of nucleic acid/DNA, confirmed by annexin V/PI and DAPI respectively. Secondary protein structure at 1656 cm(-1) (α-helix) was reduced and peak position of β-sheet structure (1637 cm(-1) ) was shifted to lower frequency. Alteration in apoptotic proteins was demonstrated via caspase-3/7 activity induction.

CONCLUSIONS

High melatonin concentration exerted anti-cancer effects by changing biomolecular structure of lipids, nucleic acids and proteins, supporting its enhancement of apoptotic induction.

Opportunities for live cell FT-infrared imaging: macromolecule identification with 2D and 3D localization

Infrared (IR) spectromicroscopy, or chemical imaging, is an evolving technique that is poised to make significant contributions in the fields of biology and medicine. Recent developments in sources, detectors, measurement techniques and speciman holders have now made diffraction-limited Fourier transform infrared (FTIR) imaging of cellular chemistry in living cells a reality. The availability of bright, broadband IR sources and large area, pixelated detectors facilitate live cell imaging, which requires rapid measurements using non-destructive probes. In this work, we review advances in the field of FTIR spectromicroscopy that have contributed to live-cell two and three-dimensional IR imaging, and discuss several key examples that highlight the utility of this technique for studying the structure and chemistry of living cells.

The characterisation of pluripotent and multipotent stem cells using Fourier transform infrared microspectroscopy

Fourier transform infrared (FTIR) microspectroscopy shows potential as a benign, objective and rapid tool to screen pluripotent and multipotent stem cells for clinical use. It offers a new experimental approach that provides a holistic measurement of macromolecular composition such that a signature representing the internal cellular phenotype is obtained. The use of this technique therefore contributes information that is complementary to that acquired by conventional genetic and immunohistochemical methods.

The action of all-trans-retinoic acid (ATRA) and synthetic retinoid analogues (EC19 and EC23) on human pluripotent stem cells differentiation investigated using single cell infrared microspectroscopy

All trans-retinoic acid (ATRA) is widely used to direct the differentiation of cultured stem cells. When exposed to the pluripotent human embryonal carcinoma (EC) stem cell line, TERA2.cl.SP12, ATRA induces ectoderm differentiation and the formation of neuronal cell types. We have previously generated synthetic analogues of retinoic acid (EC23 and EC19) which also induce the differentiation of EC cells. Even though EC23 and EC19 have similar chemical structures, they have differing biochemical effects in terms of EC cell differentiation. EC23 induces neuronal differentiation in a manner similar to ATRA, whereas EC19 directs the cells to form epithelial-like derivatives. Previous MALDI-TOF MS analysis examined the response of TERA2.cl.SP12 cells after exposure to ATRA, EC23 and EC19 and further demonstrated the similarly in the effect of ATRA and EC23 activity whilst responses to EC19 were very different. In this study, we show that Fourier Transform Infrared Micro-Spectroscopy (FT-IRMS) coupled with appropriate scatter correction and multivariate analysis can be used as an effective tool to further investigate the differentiation of human pluripotent stem cells and monitor the alternative affects different retinoid compounds have on the induction of differentiation. FT-IRMS detected differences between cell populations as early as 3 days of compound treatment. Populations of cells treated with different retinoid compounds could easily be distinguished from one another during the early stages of cell differentiation. These data demonstrate that FT-IRMS technology can be used as a sensitive screening technique to monitor the status of the stem cell phenotype and progression of differentiation along alternative pathways in response to different compounds.

3D spectral imaging with synchrotron Fourier transform infrared spectro-microtomography

We report Fourier transform infrared spectro-microtomography, a nondestructive three-dimensional imaging approach that reveals the distribution of distinctive chemical compositions throughout an intact biological or materials sample. The method combines mid-infrared absorption contrast with computed tomographic data acquisition and reconstruction to enhance chemical and morphological localization by determining a complete infrared spectrum for every voxel (millions of spectra determined per sample).

Oral cancer diagnostics based on infrared spectral markers and wax physisorption kinetics

Infrared microspectroscopy is an emerging approach for disease analysis owing to its capability for in situ chemical characterization of pathological processes. Synchrotron-based infrared microspectroscopy (SR-IMS) provides ultra-high spatial resolution for profiling biochemical events associated with disease progression. Spectral alterations were observed in cultured oral cells derived from healthy, precancerous, primary, and metastatic cancers. An innovative wax-physisorption-based kinetic FTIR imaging method for the detection of oral precancer and cancer was demonstrated successfully. The approach is based on determining the residual amount of paraffin wax (C(25)H(52)) or beeswax (C(46)H(92)O(2)) on a sample surface after xylene washing. This amount is used as a signpost of the degree of physisorption that altered during malignant transformation. The results of linear discriminant analysis (LDA) of oral cell lines indicated that the methylene (CH(2)) and methyl group (CH(3)) stretching vibrations in the range of 3,000-2,800 cm(-1) have the highest accuracy rate (89.6 %) to discriminate the healthy keratinocytes (NHOK) from cancer cells. The results of wax-physisorption-based FTIR imaging showed a stronger physisorption with beeswax in oral precancerous and cancer cells as compared with that of NHOK, which showed a strong capability with paraffin wax. The infrared kinetic study of oral cavity tissue showed a consistency in the wax physisorption of the cell lines. On the basis of our findings, these results show the potential use of wax-physisorption-based kinetic FTIR imaging for the early screening of oral cancer lesions and the chemical changes during oral carcinogenesis.