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Pittsburgh, PA, United States

Mathew S.,University of Pittsburgh | Jaramillo M.,University of Pittsburgh | Zhang X.,Central China Normal University | Zhang L.A.,University of Pittsburgh | And 4 more authors.
BMC Systems Biology | Year: 2012

Background: Lineage specific differentiation of human embryonic stem cells (hESCs) is largely mediated by specific growth factors and extracellular matrix molecules. Growth factors initiate a cascade of signals which control gene transcription and cell fate specification. There is a lot of interest in inducing hESCs to an endoderm fate which serves as a pathway towards more functional cell types like the pancreatic cells. Research over the past decade has established several robust pathways for deriving endoderm from hESCs, with the capability of further maturation. However, in our experience, the functional maturity of these endoderm derivatives, specifically to pancreatic lineage, largely depends on specific pathway of endoderm induction. Hence it will be of interest to understand the underlying mechanism mediating such induction and how it is translated to further maturation. In this work we analyze the regulatory interactions mediating different pathways of endoderm induction by identifying co-regulated transcription factors.Results: hESCs were induced towards endoderm using activin A and 4 different growth factors (FGF2 (F), BMP4 (B), PI3KI (P), and WNT3A (W)) and their combinations thereof, resulting in 15 total experimental conditions. At the end of differentiation each condition was analyzed by qRT-PCR for 12 relevant endoderm related transcription factors (TFs). As a first approach, we used hierarchical clustering to identify which growth factor combinations favor up-regulation of different genes. In the next step we identified sets of co-regulated transcription factors using a biclustering algorithm. The high variability of experimental data was addressed by integrating the biclustering formulation with bootstrap re-sampling to identify robust networks of co-regulated transcription factors. Our results show that the transition from early to late endoderm is favored by FGF2 as well as WNT3A treatments under high activin. However, induction of late endoderm markers is relatively favored by WNT3A under high activin.Conclusions: Use of FGF2, WNT3A or PI3K inhibition with high activin A may serve well in definitive endoderm induction followed by WNT3A specific signaling to direct the definitive endoderm into late endodermal lineages. Other combinations, though still feasible for endoderm induction, appear less promising for pancreatic endoderm specification in our experiments. © 2012 Mathew et al.; licensee BioMed Central Ltd.

Yagi H.,Massachusetts General Hospital | Yagi H.,Keio University | Soto-Gutierrez A.,Massachusetts General Hospital | Soto-Gutierrez A.,Center for Innovative Regenerative Therapies | And 10 more authors.
Molecular Therapy | Year: 2010

Excessive systemic inflammation following trauma, sepsis, or burn could lead to distant organ damage. The transplantation of bone marrow stromal cells or mesenchymal stem cells (MSCs) has been reported to be an effective treatment for several immune disorders by modulating the inflammatory response to injury. We hypothesized that MSCs can dynamically secrete systemic factors that can neutralize the activity of inflammatory cytokines. In this study, we showed that cocultured MSCs are able to decrease nuclear factor -B (NFB) activation in target epithelial cells incubated in inflammatory serum conditions. Proteomic screening revealed a responsive secretion of soluble tumor necrosis factor (TNF) receptor 1 (sTNFR1) when MSCs were exposed to lipopolysaccharide (LPS)-stimulated rat serum. The responsive effect was eliminated when NFB activation was blocked in MSCs. Intramuscular transplantation of MSCs in LPS-endotoxic rats decreased a panel of inflammatory cytokines and inflammatory infiltration of macrophages and neutrophils in lung, kidney, and liver when compared to controls. These results suggest that improvements of inflammatory responses in animal models after local transplantation of MSCs are at least, in part, explained by the NFB-dependent secretion of sTNFR1 by MSCs. © The American Society of Gene & Cell Therapy.

Duncan A.W.,University of Pittsburgh | Duncan A.W.,McGowan Institute for Regenerative Medicine | Soto-Gutierrez A.,University of Pittsburgh | Soto-Gutierrez A.,McGowan Institute for Regenerative Medicine | Soto-Gutierrez A.,Center for Innovative Regenerative Therapies
Current Opinion in Organ Transplantation | Year: 2013

PURPOSE OF REVIEW: Significant recent developments have occurred in the field of liver regeneration. Although the regenerative response to partial hepatectomy has been studied extensively, in recent years the use of new experimental approaches has incorporated a fresh look that may lead to a better understanding of hepatocyte dysfunction and regeneration. RECENT FINDINGS: Liver injury promotes the regenerative responses that are relatively rare in healthy livers. Current research efforts focus on the mechanisms of hepatocyte adaptation in response to liver injury. We will discuss how hepatic aneuploidy and polyploidy contributes to liver regeneration, as well as new modalities to study cellular interactions using the organ-specific microenvironment. SUMMARY: High mortality is generally limited to patients who develop terminal liver failure, which occurs when regenerative responses are unable to compensate for liver injury. Cellular adaptations and organ microenvironment changes are present during disease processes. This review aims to provide insights into the innovative approaches taken to investigate regeneration in liver diseases. © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins.

Hansel M.C.,University of Pittsburgh | Hansel M.C.,McGowan Institute for Regenerative Medicine | Gramignoli R.,Karolinska Institutet | Blake W.,Pfizer | And 13 more authors.
Cell Transplantation | Year: 2014

Hepatocyte transplantation has been used to treat liver disease. The availability of cells for these procedures is quite limited. Human embryonic stem cells (hESCs) and induced pluripotent stem cells (hiPSCs) may be a useful source of hepatocytes for basic research and transplantation if efficient and effective differentiation protocols were developed and problems with tumorigenicity could be overcome. Recent evidence suggests that the cell of origin may affect hiPSC differentiation. Thus, hiPSCs generated from hepatocytes may differentiate back to hepatocytes more efficiently than hiPSCs from other cell types. We examined the efficiency of reprogramming adult and fetal human hepatocytes. The present studies report the generation of 40 hiPSC lines from primary human hepatocytes under feeder-free conditions. Of these, 37 hiPSC lines were generated from fetal hepatocytes, 2 hiPSC lines from normal hepatocytes, and 1 hiPSC line from hepatocytes of a patient with Crigler-Najjar syndrome, type 1. All lines were confirmed reprogrammed and expressed markers of pluripotency by gene expression, flow cytometry, immunocytochemistry, and teratoma formation. Fetal hepatocytes were reprogrammed at a frequency over 50-fold higher than adult hepatocytes. Adult hepatocytes were only reprogrammed with six factors, while fetal hepatocytes could be reprogrammed with three (OCT4, SOX2, NANOG) or four factors (OCT4, SOX2, NANOG, LIN28 or OCT4, SOX2, KLF4, C-MYC). The increased reprogramming efficiency of fetal cells was not due to increased transduction efficiency or vector toxicity. These studies confirm that hiPSCs can be generated from adult and fetal hepatocytes including those with genetic diseases. Fetal hepatocytes reprogram much more efficiently than adult hepatocytes, although both could serve as useful sources of hiPSC-derived hepatocytes for basic research or transplantation. © 2014 Cognizant Comm. Corp.

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