Evaluation of metabolomic changes as a biomarker of chondrogenic differentiation in 3D-cultured human mesenchymal stem cells using proton (1H) nuclear magnetic resonance spectroscopy

Fabrication of stem cell heterospheroids with sustained-release chitosan and poly(lactic-co-glycolic acid) microspheres to guide cell fate toward chondrogenic differentiation

Mesenchymal stem cell (MSC)-based therapies show great potential in treating various diseases. However, control of the fate of injected cells needs to be improved. In this work, we developed an efficient methodology for modulating chondrogenic differentiation of MSCs. We fabricated heterospheroids with two sustained-release depots, a quaternized chitosan microsphere (QCS-MP) and a poly (lactic-co-glycolic acid) microsphere (PLGA-MP). The results show that heterospheroids composed of 1 × 104 to 5 × 104 MSCs formed rapidly during incubation in methylcellulose medium and maintained high cell viability in long-term culture. The MPs were uniformly distributed in the heterospheroids, as shown by confocal laser scanning microscopy. Incorporation of transforming growth factor beta 3 into QCS-MPs and of dexamethasone into PLGA-MPs significantly promoted the expression of chondrogenic genes and high accumulation of glycosaminoglycan in heterospheroids. Changes in crucial metabolites in the dual drug depot-engineered heterospheroids were also evaluated using 1H NMR-based metabolomics analysis to verify their successful chondrogenic differentiation. Our heterospheroid fabrication platform could be used in tissue engineering to study the effects of various therapeutic agents on stem cell fate.

Metabolomic Applications in Stem Cell Research: a Review

This review describes the use of metabolomics to study stem cell (SC) characteristics and function, excluding SCs in cancer research, suited to a fully dedicated text. The interest in employing metabolomics in SC research has consistently grown and emphasis is, here, given to developments reported in the past five years. This text informs on the existing methodologies and their complementarity regarding the information provided, comprising untargeted/targeted approaches, which couple mass spectrometry or nuclear magnetic resonance spectroscopy with multivariate analysis (and, in some cases, pathway analysis and integration with other omics), and more specific analytical approaches, namely isotope tracing to highlight particular metabolic pathways, or in tandem microscopic strategies to pinpoint characteristics within a single cell. The bulk of this review covers the existing applications in various aspects of mesenchymal SC behavior, followed by pluripotent and neural SCs, with a few reports addressing other SC types. Some of the central ideas investigated comprise the metabolic/biological impacts of different tissue/donor sources and differentiation conditions, including the importance of considering 3D culture environments, mechanical cues and/or media enrichment to guide differentiation into specific lineages. Metabolomic analysis has considered cell endometabolomes and exometabolomes (fingerprinting and footprinting, respectively), having measured both lipid species and polar metabolites involved in a variety of metabolic pathways. This review clearly demonstrates the current enticing promise of metabolomics in significantly contributing towards a deeper knowledge on SC behavior, and the discovery of new biomarkers of SC function with potential translation to in vivo clinical practice.

Monitoring membrane viscosity in differentiating stem cells using BODIPY-based molecular rotors and FLIM

Membrane fluidity plays an important role in many cell functions such as cell adhesion, and migration. In stem cell lines membrane fluidity may play a role in differentiation. Here we report the use of viscosity-sensitive fluorophores based on a BODIPY core, termed “molecular rotors”, in combination with Fluorescence Lifetime Imaging Microscopy, for monitoring of plasma membrane viscosity changes in mesenchymal stem cells (MSCs) during osteogenic and chondrogenic differentiation. In order to correlate the viscosity values with membrane lipid composition, the detailed analysis of the corresponding membrane lipid composition of differentiated cells was performed by time-of-flight secondary ion mass spectrometry. Our results directly demonstrate for the first time that differentiation of MSCs results in distinct membrane viscosities, that reflect the change in lipidome of the cells following differentiation.

Metabolomic Analysis Reveals That the Mechanism of Astaxanthin Improves the Osteogenic Differentiation Potential in Bone Marrow Mesenchymal Stem Cells

At present, little research has been done on the metabolic phenotype of the differentiation of mesenchymal stem cells (MSCs) into osteoblasts. In this study, the effect of astaxanthin on improving osteogenic differentiation potential of mesenchymal stem cells was studied by metabolomics. Results showed that L-methionine, L-tyrosine, and 2-hydroxycinnamic acid were upregulated in MSCs treated with astaxanthin, while L-lysine, L-pipecolic acid, L-histidine, L-arginine, D-fructose, and L-aspartic acid were downregulated in samples treated with astaxanthin. In addition, astaxanthin exhibited a significant dose-dependent relationship with these markers. Metabolic pathway enrichment analysis revealed that AST mainly regulated phenylalanine metabolism; phenylalanine, tyrosine, and tryptophan biosynthesis; and pantothenate and CoA biosynthesis during the process of osteogenic differentiation of MSCs. Furthermore, the staining results showed that astaxanthin could actively promote the osteogenic differentiation of mesenchymal stem cells. These findings clearly indicate that astaxanthin plays an important role in inducing osteogenic differentiation of mesenchymal stem cells. In addition, the changed metabolites can be used to monitor the differentiation process.

Integrative Metabolic Pathway Analysis Reveals Novel Therapeutic Targets in Osteoarthritis

In osteoarthritis (OA), impairment of cartilage regeneration can be related to a defective chondrogenic differentiation of mesenchymal stromal cells (MSCs). Therefore, understanding the proteomic- and metabolomic-associated molecular events during the chondrogenesis of MSCs could provide alternative targets for therapeutic intervention. Here, a SILAC-based proteomic analysis identified 43 proteins related with metabolic pathways whose abundance was significantly altered during the chondrogenesis of OA human bone marrow MSCs (hBMSCs). Then, the level and distribution of metabolites was analyzed in these cells and healthy controls by matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI), leading to the recognition of characteristic metabolomic profiles at the early stages of differentiation. Finally, integrative pathway analysis showed that UDP-glucuronic acid synthesis and amino sugar metabolism were downregulated in OA hBMSCs during chondrogenesis compared with healthy cells. Alterations in these metabolic pathways may disturb the production of hyaluronic acid (HA) and other relevant cartilage extracellular matrix (ECM) components. This work provides a novel integrative insight into the molecular alterations of osteoarthritic MSCs and potential therapeutic targets for OA drug development through the enhancement of chondrogenesis.

High-fat diet in pregnant rats and adverse fetal outcome

Background: Although pregestational obesity has been associated with increased risk of adverse fetal outcome, the mechanisms behind are not known. We aimed to investigate the influence of the maternal metabolic state on fetal outcome in rats exposed to either a high-fat diet (HFD) or a control diet (CD). We also investigated the impact of serum collected from HFD/CD pregnant rats on CD embryonic development in whole-embryo cultures. Material and methods: On gestational day 0, 9, 10, or 20 maternal plasma/serum samples were collected as pregnancies were terminated for the estimations of maternal metabolic state and embryo-fetal development. We measured embryonic gene expression of ROS scavenger enzymes as well as genes involved in inflammation in maternal adipose tissue. Results: In HFD maternal plasma/serum, concentrations of glucose, β-hydroxybutyrate, branched-chain amino acids, and leptin were increased, whereas those of triacylglycerol, cholesterol, and palmitic, oleic, linoleic, and α-linolenic acids were decreased. Gene expression of CuZnSOD, IL-6, IL-10, and resistin was increased in HFD maternal adipose tissue, whereas that of CuZnSOD and MnSOD was decreased in HFD-exposed embryos. HFD caused retention of most fatty acids in the maternal liver as well. Conclusion: HFD alters the maternal metabolic state, increases fetal resorptions in vivo, and increases the rate of fetal/embryonic malformations both in vivo and in vitro. These findings suggest that metabolic disturbances in HFD pregnant rats have profound adverse developmental effects in the offspring.

Maintenance of human chondrogenic phenotype on a dendrimer-immobilized surface for an application of cell sheet engineering

BACKGROUND

Dedifferentiation of chondrocytes during cell expansion is one of the barriers in tissue construction for cartilage repair. To understand chondrocyte behavior and improve cell expansion in monolayer culture, this study investigated the effects of morphological changes and cellular aggregation on the maintenance of chondrogenic capacity by observing the expression patterns of chondrogenic (collagen type II and aggrecan) and dedifferentiation (collagen type I) markers. Primary human chondrocytes were cultured on either a polystyrene surface (PS) or a polyamidoamine dendrimer surface with a fifth-generation (G5) dendron structure to create a one-step process of cell expansion and the maintenance of chondrogenic activities prior to the construction of cell sheets.

RESULTS

During the first two passages (P0 - P2), the relative mRNA level of collagen type II decreased in all cultures, while that of collagen type I increased. Remarkably, the level of collagen type II was higher and aggrecan was retained in the chondrocytes, forming cell aggregates and showing some round-shaped cells with less production of stress fibers on the G5 surface compared to fibroblast-like chondrocytes with abundant stress fibers on the PS surface. The numbers of P2 chondrocytes on the G5 and PS surfaces were nearly the same and sufficient for construction of chondrocyte sheets using a temperature-responsive plate. Without a supporting material during cell sheet manipulation, chondrocyte sheets spontaneously detached and exhibited a honeycomb-like structure of stress fibers. Unlike the chondrocyte sheets constructed from cells on the PS surface, the chondrocyte sheets from cells on the G5 surface had higher chondrogenic activities, as evidenced by the high expression of chondrogenic markers and the low expression of dedifferentiation markers.

CONCLUSIONS

The one-step process of cell expansion and maintenance of chondrogenic activity could be obtained using the G5 surface. Human chondrocyte sheets were successfully constructed with high chondrogenic activity. These findings may lead to an alternative cultivation technique for human chondrocytes that offers high clinical potential in autologous chondrocyte implantation.

Combined use of adipose derived stem cells and TGF-β3 microspheres promotes articular cartilage regeneration in vivo

We investigated enhancement of articular cartilage regeneration using a combination of human adipose derived stem cells (hADSCs) and TGF-β3 microspheres (MS) in vivo. Poly-lactic-co-glycolic acid (PLGA)MS were prepared using a solid/oil/water emulsion solvent evaporation-extraction method. The morphology of the MS was evaluated by scanning electron microscopy (SEM). The release characteristic of the TGF-β3 MS was evaluated. A New Zealand rabbit model for experimental osteoarthritis (OA) was established using the anterior medial meniscus excision method. Thirty OA rabbits were divided randomly into three groups according to different treatments of the right knee joints on day 7 after surgery: hADSCs/MS group received injection of both hADSCs and TGF-β3 MS; hADSCs group was injected with hADSCs; control group was injected with normal saline. Gross observation, histological staining and RT-PCR for collagen II and aggrecan) were used to assess the severity of OA and for evaluating the effect of combined use of hADSCs and TGF-β3 MS on articular cartilage regeneration in vivo. The MS were spherical with a smooth surface and the average diameter was 28 ± 2.3 µm. The encapsulation efficiency test showed that 73.8 ± 2.9% of TGF-β3 were encapsulated in the MS. The release of TGF- β3 lasted for at least 30 days. At both 6 and 12 weeks after injection, three groups exhibited different degrees of OA. Histological analysis showed that the hADSCs/MS group exhibited less OA than the hADSCs group, and the control group exhibited the most severe OA. Real-time RT-PCR showed that the gene expression of both collagen II and aggrecan were significantly up-regulated in the hADSCs/MS group. At 12 weeks after injection, the hADSCs/MS group also exhibited less OA than the other two groups. Combined use of hADSCs and TGF-β3 MS promoted articular cartilage regeneration in rabbit OA models.

Metabolomics Analysis of the Osteogenic Differentiation of Umbilical Cord Blood Mesenchymal Stem Cells Reveals Differential Sensitivity to Osteogenic Agents

Mesenchymal stem cells (MSCs) of fetal origin, such as umbilical cord blood MSCs (UCB MSCs), have emerged as a promising cell source for musculoskeletal tissue regeneration because of their higher proliferation potential, lack of donor site morbidity, and their off-the-shelf potential. MSCs differentiated toward the osteogenic lineage exhibit a specific metabolic phenotype characterized by reliance to oxidative phosphorylation for energy production and reduced glycolytic rates. Currently, limited information exists on the metabolic transitions at different stages of the osteogenic process after osteoinduction with different agents. Herein, the osteoinduction efficiency of BMP-2 and dexamethasone on UCB MSCs was assessed using gas chromatography-mass spectrometry (GC-MS) metabolomics analysis, revealing metabolic discrepancies at 7, 14, and 21 days of induction. Whereas both agents when administered individually were able to induce collagen I, osteocalcin, and osteonectin expression, BMP-2 was less effective than dexamethasone in promoting alkaline phosphatase expression. The metabolomics analysis revealed that each agent induced distinct metabolic alterations, including changes in amino acid pools, glutaminolysis, one-carbon metabolism, glycolysis, and tricarboxylic acid cycle. Importantly, we showed that in vitro-differentiated UCB MSCs acquire a metabolic physiology similar to primary osteoblasts when induced with dexamethasone but not with BMP-2, highlighting the fact that metabolomics analysis is sensitive enough to reveal potential differences in the osteogenic efficiency and can be used as a quality control assay for evaluating the osteogenic process.

Noninvasive and repetitive measurement of cellular metabolite from human osteosarcoma cells (MG-63) using 3.0 tesla proton (1 H) MR spectroscopy

PURPOSE

This study suggests a noninvasive and repetitive measurement method using ¹ H magnetic resonance spectroscopy to monitor changes in cellular metabolites within a single sample.

METHODS

Longitudinal acquisition of cellular metabolites from three-dimensional cultured human osteosarcoma (MG-63) cells was conducted using 3.0 Tesla ¹ H MRS for 2 weeks at three time points: days 1, 7, and 14. During the MR spectroscopy (MRS) scan, cell specimen temperatures were kept constant at 37°C by a lab-developed magnetic resonance compatible thermostatic device. A DNA assay and live/dead staining of the cell specimens were carried out at each time point to verify the MRS measurements.

RESULTS

Cell viability in the proposed device did not significantly differ from that of cells in a conventional incubator (P = 0.946). Cell proliferation and choline concentration increased during the first week, but remained constant during the second week. Lactate did not change during the first week, but increased during the second week. Likewise, cell viability remained constant until day 7, then decreased.

CONCLUSION

The proposed MRS technique results in a survivable environment for longitudinal studies of cells and provides a new way to measure metabolomic changes over time in single specimens of cells. Magn Reson Med 76:1912-1918, 2016. © 2016 International Society for Magnetic Resonance in Medicine.

Characterization of lipidic markers of chondrogenic differentiation using mass spectrometry imaging

Mesenchymal stem cells (MSC) are an interesting alternative for cell-based therapy of cartilage defects attributable to their capacity to differentiate toward chondrocytes in the process termed chondrogenesis. The metabolism of lipids has recently been associated with the modulation of chondrogenesis and also with the development of pathologies related to cartilage degeneration. Information about the distribution and modulation of lipids during chondrogenesis could provide a panel of putative chondrogenic markers. Thus, the discovery of new lipid chondrogenic markers could be highly valuable for improving MSC-based cartilage therapies. In this work, MS imaging was used to characterize the spatial distribution of lipids in human bone marrow MSCs during the first steps of chondrogenic differentiation. The analysis of MSC micromasses at days 2 and 14 of chondrogenesis by MALDI-MSI led to the identification of 20 different lipid species, including fatty acids, sphingolipids, and phospholipids. Phosphocholine, several sphingomyelins, and phosphatidylcholines were found to increase during the undifferentiated chondrogenic stage. A particularly detected lipid profile was verified by TOF secondary ion MS. Using this technology, a higher intensity of phosphocholine-related ions was observed in the peripheral region of the micromasses collected at day 14.