Senescing Human Bone-Marrow-Derived Clonal Mesenchymal Stem Cells Have Altered Lysophospholipid Composition and Functionality

An Intracellular Metabolic Signature as a Potential Donor-Independent Marker of the Osteogenic Differentiation of Adipose Tissue Mesenchymal Stem Cells

This paper describes an untargeted NMR metabolomics study to identify potential intracellular donor-dependent and donor-independent metabolic markers of proliferation and osteogenic differentiation of human adipose mesenchymal stem cells (hAMSCs). The hAMSCs of two donors with distinct proliferating/osteogenic characteristics were fully characterized regarding their polar endometabolome during proliferation and osteogenesis. An 18-metabolites signature (including changes in alanine, aspartate, proline, tyrosine, ATP, and ADP, among others) was suggested to be potentially descriptive of cell proliferation, independently of the donor. In addition, a set of 11 metabolites was proposed to compose a possible donor-independent signature of osteogenesis, mostly involving changes in taurine, glutathione, methylguanidine, adenosine, inosine, uridine, and creatine/phosphocreatine, choline/phosphocholine and ethanolamine/phosphocholine ratios. The proposed signatures were validated for a third donor, although they require further validation in a larger donor cohort. We believe that this proof of concept paves the way to exploit metabolic markers to monitor (and potentially predict) cell proliferation and the osteogenic ability of different donors.

Senescence-Associated Metabolomic Phenotype in Primary and iPSC-Derived Mesenchymal Stromal Cells

Long-term culture of primary cells is characterized by functional and secretory changes, which ultimately result in replicative senescence. It is largely unclear how the metabolome of cells changes during replicative senescence and if such changes are consistent across different cell types. We have directly compared culture expansion of primary mesenchymal stromal cells (MSCs) and induced pluripotent stem cell-derived MSCs (iMSCs) until they reached growth arrest. Both cell types acquired similar changes in morphology, in vitro differentiation potential, senescence-associated β-galactosidase, and DNA methylation. Furthermore, MSCs and iMSCs revealed overlapping gene expression changes, particularly in functional categories related to metabolic processes. We subsequently compared the metabolomes of MSCs and iMSCs and observed overlapping senescence-associated changes in both cell types, including downregulation of nicotinamide ribonucleotide and upregulation of orotic acid. Taken together, replicative senescence is associated with a highly reproducible senescence-associated metabolomics phenotype, which may be used to monitor the state of cellular aging.

Metabolomics Approach Based on Multivariate Techniques for Blood Transfusion Reactions

Blood transfusions temporarily improve the physical state of the patient but exert widespread effects on immune and non-immune systems. Perioperative allogeneic blood transfusions (ABT) are associated with various risks, including coagulopathy, incompatibility, transmission of infectious agents, and allergic reactions. Nevertheless, little is known about the global metabolic alterations that reflect the possible reactions of blood transfusions. In this study, we investigated metabolite changes generated by ABT in a rat model using metabolomics technology. To further profile the “metabolome” after blood transfusions, we used both liquid chromatography-quadrupole time-of-flight high-definition mass spectrometry and gas chromatography-mass spectrometry. ABT promoted a stimulatory microenvironment associated with a relative increase in glucose transporter 1/4 (GLUT1/GLUT4) expression. Supporting this result, glucose metabolism-related enzyme IRS1 and interleukin-6 (IL-6) were abnormally expressed, and levels of lysophosphatidylcholine (LysoPC) and its related enzyme phospholipase A2 (PLA2) were significantly altered in allogeneic groups compared to those in autologous groups. Finally, amino acid metabolism was also altered following ABT. Taken together, our results show a difference between autologous and allogeneic blood transfusions and demonstrate correlations with cancer-associated metabolic changes. Our data provide endogenous information for a better understanding of blood transfusion reactions.

Comparative study on metabolite level in tissue-specific human mesenchymal stem cells by an ultra-performance liquid chromatography quadrupole time of flight mass spectrometry

Mesenchymal stem cells (MSCs) are a promising therapeutic option for cell-based therapy due to their immunomodulatory and regenerative properties. They can be isolated from various adult tissues, including bone marrow, fat, dental tissue, and glandular tissue. Although they share common characteristics, little is known about the biological differences between MSC populations derived from different tissues. In this study, we used MS to compare the endogenous metabolite level in the human MSCs originating from the bone marrow, adipose tissue, periodontal ligaments, and salivary glands. Using an optimized metabolomics technique, we verified that human MSCs exhibit differences in the endogenous metabolite level depending on their source material, while the multivariate analysis showed that 5 lysophosphatidylcholines and 3 lysophosphatidylethanolamines can serve as markers for the discrimination between MSC sources and may be related to differences in their differentiation capacity. These results may significantly contribute to further mechanistic studies on the MSCs and provide novel insights into the properties and optimal usage of MSCs from different tissues.

Extracellular vesicles released by fibroblasts undergoing H-Ras induced senescence show changes in lipid profile

Cells release extracellular vesicles (EVs) in their environment and cellular lipids play an important role in their formation, secretion and uptake. Besides, there is also evidence that EV transferred lipids impact on recipient’s cell signaling. Cellular senescence is characterized by a state of permanent proliferation arrest and represents a barrier towards the development of neoplastic lesions. A peculiar feature of senescence is the release of many soluble factors, the so-called Senescence-Associated Secretory Phenotype, which play a key role in triggering paracrine senescence signals. Recently, evidences have suggested that this phenotype includes not only soluble factors, but also EVs. To identify lipid signatures associated with H-Ras-induced senescence in EVs, we expressed active H-Ras (H-RasV12) in human fibroblasts and investigated how it affects EV release and lipid composition. An enrichment of hydroxylated sphingomyelin, lyso- and ether-linked phospholipids and specific H-Ras-induced senescence signatures, e.g. sphingomyelin, lysophosphatidic acid and sulfatides, were found in EVs compared to cells. Furthermore, H-RasV12 expression in fibroblasts was associated with higher levels of tetraspanins involved in vesicle formation.

Mesenchymal Stem Cells Respond to Hypoxia by Increasing Diacylglycerols

Mesenchymal stem cells (MSC) are currently being tested clinically for a plethora of conditions, with most approaches relying on the secretion of paracrine signals by MSC to modulate the immune system, promote wound healing, and induce angiogenesis. Hypoxia has been shown to affect MSC proliferation, differentiation, survival and secretory profile. Here, we investigate changes in the lipid composition of human bone marrow-derived MSC after exposure to hypoxia. Using mass spectrometry, we compared the lipid profiles of MSC derived from five different donors, cultured for two days in either normoxia (control) or hypoxia (1% oxygen). Hypoxia induced a significant increase of total triglycerides, fatty acids and diacylglycerols (DG). Remarkably, reduction of DG levels using the phosphatidylcholine-specific phospholipase C inhibitor D609 inhibited the secretion of VEGF and Angiopoietin-2, but increased the secretion of interleukin-8, without affecting significantly their respective mRNA levels. Functionally, incubation of MSC in hypoxia with D609 inhibited the potential of the cells to promote migration of human endothelial cells in a wound/scratch assay. Hence, we show that hypoxia induces in MSC an increase of DG that may affect the angiogenic potential of these cells.