Smita Jagtap

Publications

• Effect of chemopreventive agents on differentiation of mouse embryonic stem cells.

  Vilas Wagh, Smita Jagtap, Kesavan Meganathan, Shiva Prasad Potta, Johannes Winkler, Juergen Hescheler, Agapios Sachinidis

  Frontiers in bioscience (Elite edition). 01/2012; 4:156-68.

  Chemopreventive agents are derived from edible plants and from ancient time is a part of daily intake for many humans and animals. There are several lines of compelling evidence from epidemiological, clinical and laboratory studies that these dietary constituents are associated in reducing cancer ri... [more] Chemopreventive agents are derived from edible plants and from ancient time is a part of daily intake for many humans and animals. There are several lines of compelling evidence from epidemiological, clinical and laboratory studies that these dietary constituents are associated in reducing cancer risks. However, developmental toxicity of these natural compounds cannot be excluded. In the present study, we examined the effect of chemopreventive agents on the differentiation of mouse embryonic stem cells (ESCs) as an in vitro embryotoxicity model. We assumed that inhibition of developmentally regulated genes in vitro might predict developmental toxicity also under in vivo conditions. We found that epigallocatechin gallate (EGCG) (20 microM) induced the expression of mesodermal and cardiomyocyte genes and a significant increase in the number and the percentage of cardiomyocytes. The increase of the subpopulation correlated with higher numbers of beating foci and beating frequencies. Curcumin on the other hand at 0.4 mM was seen to enhance expression of ectodermal transcripts. Quercetin (2.5 microM) was found to inhibit several developmentally regulated genes.
• 4.81

  Impact points

  Development of a neural teratogenicity test based on human embryonic stem cells: response to retinoic acid exposure.

  Silvia Colleoni, Cesare Galli, John Antony Gaspar, Kesavan Meganathan, Smita Jagtap, Jurgen Hescheler, Agapios Sachinidis, Giovanna Lazzari

  Toxicological sciences : an official journal of the Society of Toxicology. 09/2011; 124(2):370-7.

  The aim of this study was the development of an alternative testing method based on human embryonic stem cells for prenatal developmental toxicity with particular emphasis on early neural development. To this purpose, we designed an in vitro protocol based on the generation of neural rosettes, repre... [more] The aim of this study was the development of an alternative testing method based on human embryonic stem cells for prenatal developmental toxicity with particular emphasis on early neural development. To this purpose, we designed an in vitro protocol based on the generation of neural rosettes, representing the in vitro counterpart of the developing neural plate and neural tube, and we challenged this complex cell model with retinoic acid (RA), a well-known teratogenic agent. The cells were exposed to different concentrations of RA during the process of rosettes formation. Morphological and molecular parameters were evaluated in treated as compared with untreated cells to detect both cytotoxicity and specific neural toxicity. Transcriptomic analysis was performed with microarray Affymetrix platform and validated by quantitative real-time PCR for genes relevant to early neural development such as HoxA1, HoxA3, HoxB1, HoxB4, FoxA2, FoxC1, Otx2, and Pax7. The results obtained demonstrated that neural rosette forming cells respond to RA with clear concentration-dependent morphological, and gene expression changes remarkably similar to those induced in vivo, in the developing neural tube, by RA exposure. This strict correspondence indicates that the neural rosette protocol described is capable of detecting specific teratogenic mechanisms causing perturbations of early neural development and therefore represents a promising alternative test for human prenatal developmental toxicity.
• 5.08

  Impact points

  Functional Characterization and Gene Expression Profiling of α-Smooth Muscle Actin Expressing Cardiomyocytes Derived from Murine Induced Pluripotent Stem Cells.

  Shiva Prasad Potta, Xiaowu Sheng, John Antonydas Gaspar, Kesavan Meganathan, Smita Jagtap, Kurt Pfannkuche, Johannes Winkler, Jürgen Hescheler, Symeon Papadopoulos, Agapios Sachinidis

  Stem cell reviews. 05/2011; 8(1):229-42.
• 5.08

  Impact points

  Effects of cryopreservation on the transcriptome of human embryonic stem cells after thawing and culturing.

  Vilas Wagh, Kesavan Meganathan, Smita Jagtap, John Antonydas Gaspar, Johannes Winkler, Dimitry Spitkovsky, Jürgen Hescheler, Agapios Sachinidis

  Stem cell reviews. 01/2011; 7(3):506-17.

  Human embryonic stem cells (hESCs) can be propagated indefinitely in vitro in an undifferentiated pluripotent state, can differentiate into derivatives of all three germ layers and are of considerable interest for applications in regenerative medicine. Clinical application of hESCs, however, require... [more] Human embryonic stem cells (hESCs) can be propagated indefinitely in vitro in an undifferentiated pluripotent state, can differentiate into derivatives of all three germ layers and are of considerable interest for applications in regenerative medicine. Clinical application of hESCs, however, requires reliable protocols for cryopreservation. Current protocols for cryopreservation of hESCs suffer from low recovery rates of hESCs and loss of pluripotency after thawing. We therefore studied the effects of cryopreservation on the viability, proliferation potential, and the pluripotency status of hESCs by combining cellular readouts and transcriptomics. We identified biological processes and pathways affected by cryopreservation in order to understand the limited survival rate of hESCs by comparing transcriptomes of hESCs at different time points after thawing with cells that did not undergo cryopreservation. While the transcriptomes of cells post thawing were very similar to those of control non-frozen hESCs for the early time points, we observed increased expression of genes involved in apoptosis, embryonic morphogenesis, ossification, tissue morphogenesis, regeneration, vasculature development and cell death at later time points. Our data suggest that inhibition of anoikis apoptosis and the stress-induced differentiation pathways are promising targets for improving the survival rate and maintaining pluripotency of hESCs after cryopreservation.
• 5.20

  Impact points

  Cytosine arabinoside induces ectoderm and inhibits mesoderm expression in human embryonic stem cells during multilineage differentiation.

  S Jagtap, K Meganathan, J Gaspar, V Wagh, J Winkler, J Hescheler, A Sachinidis

  British journal of pharmacology. 12/2010; 162(8):1743-56.

  Teratogenic substances induce adverse effects during the development of the embryo. Multilineage differentiation of human embryonic stem cells (hESCs) mimics the development of the embryo in vitro. Here, we propose a transcriptomic approach in hESCs for monitoring specific toxic effects of compounds... [more] Teratogenic substances induce adverse effects during the development of the embryo. Multilineage differentiation of human embryonic stem cells (hESCs) mimics the development of the embryo in vitro. Here, we propose a transcriptomic approach in hESCs for monitoring specific toxic effects of compounds as an alternative to traditional time-consuming and cost-intensive in vivo tests requiring large numbers of animals. This study was undertaken to explore the adverse effects of cytosine arabinoside (Ara-C) on randomly differentiated hESCs. Human embryonic stem cells were used to investigate the effects of a developmental toxicant Ara-C. Sublethal concentrations of Ara-C were given for two time points, day 7 and day 14 during the differentiation. Gene expression was assessed with microarrays to determine the dysregulated transcripts in presence of Ara-C. Randomly differentiated hESCs were able to generate the multilineage markers. The low concentration of Ara-C (1 nM) induced the ectoderm and inhibited the mesoderm at day 14. The induction of ectodermal markers such as MAP2, TUBB III, PAX6, TH and NESTIN was observed with an inhibition of mesodermal markers such as HAND2, PITX2, GATA5, MYL4, TNNT2, COL1A1 and COL1A2. In addition, no induction of apoptosis was observed. Gene ontology revealed unique dysregulated biological process related to neuronal differentiation and mesoderm development. Pathway analysis showed the axon guidance pathway to be dysregulated. Our results suggest that hESCs in combination with toxicogenomics offer a sensitive in vitro developmental toxicity model as an alternative to traditional animal experiments.

• Cytarabine stimulates neuronal markers in hESC derived embryoid bodies.

  S. Jagtap, K. Meganathan, V. Wagh, J. A.Gaspar, J. Winkler, J. Hescheler, A. Sachinidis

  5th Annual Meeting of German Society for Stem Cell Research (GSZ); 01/2010

  Cytosine arabinoside (cytarabine) is an antimetabolic agent, which damages DNA when the cells cycle holds in S phase. Cytarabine is mainly used in the treatment of AML and lymphomas. It has been reported to cause severe neuropsychiatric side effects in human patients under going therapy for AML. Cyt... [more] Cytosine arabinoside (cytarabine) is an antimetabolic agent, which damages DNA when the cells cycle holds in S phase. Cytarabine is mainly used in the treatment of AML and lymphomas. It has been reported to cause severe neuropsychiatric side effects in human patients under going therapy for AML. Cytarabine is also reported to be used in the study of nervous system. In the present study, we have investigated the effect of cytarabine on human embryonic stem cells (hESCs) derived randomly differentiated embryoid bodies. Cytarabine, being a developmental toxicant, exhibited cytotoxicity at high concentrations, while sub-lethal concentration of cytarabine was found to stimulate neuronal markers such as PAX6 and MAP2. In addition, low concentration of cytarabine also caused inhibition of developmental markers. To find the significant toxicity markers microarray analysis was performed with Ilumina HumanHT-12 v3 Expression BeadChip, revealing cytarabine promoted axon guidance and other pathways known to be involved in the regulation of neurogenesis in hESC embryoid bodies. In addition 124 upregulated and 416 down regulated significant genes (p < 0.05) were observed in cytarabine treated EBs compared with untreated. The significantly (p < 0.01) upregulated annotations for cytarabine treatment in the GO biological process relate to neuronal differentiation like neural morphogenesis, axonogenesis, nervous system development etc. In our work, it is shown that cytarabine can stimulate pathways and markers for neuronal differentiation and inhibit developmental markers.
• 4.71

  Impact points

  Chemoprotective mechanism of the natural compounds, epigallocatechin-3-o-gallate, quercetin and curcumin against cancer and cardiovascular diseases.

  Smita Jagtap, Kesavan Meganathan, Vilas Wagh, Johannes Winkler, Jürgen Hescheler, Agapios Sachinidis

  Current medicinal chemistry. 02/2009; 16(12):1451-62.

  Cancer and cardiovascular disease (CVD) chemoprevention can be achieved by the use of natural, synthetic, or biologic compounds to reverse, suppress, or prevent the development of diseases. Chemoprevention is a potential anti-cancer approach, which has reduced secondary effects in comparison to clas... [more] Cancer and cardiovascular disease (CVD) chemoprevention can be achieved by the use of natural, synthetic, or biologic compounds to reverse, suppress, or prevent the development of diseases. Chemoprevention is a potential anti-cancer approach, which has reduced secondary effects in comparison to classical prophylaxis. Natural compounds such as flavonoids reduce oxidative stress, which is the most likely mechanism in the protective effects of these compounds. Even though the exact mechanisms of action are not well understood another central action mechanism of polyphenolic flavonoids seems to be an induction of apoptosis as demonstrated in numerous cellular systems. Moreover, flavonoids may modulate protein and lipid kinase signaling pathways. Understanding the mechanism of these natural products will contribute to the development of more specific preventive strategies against cancer and CVD. Much of the research in the field is focused on epigallocatechin-3-O-gallate (EGCG), quercetin and curcumin, which were found to have beneficial effects against cancer and CVD. We review the chemoprotective mechanisms through which these natural compounds exert their beneficial effects against cancer and CVDs.