Encapsulation of Human-Bone-Marrow-Derived Mesenchymal Stem Cells in Small Alginate Beads Using One-Step Emulsification by Internal Gelation: In Vitro, and In Vivo Evaluation in Degenerate Intervertebral Disc Model

Cell microencapsulation in gel beads contributes to many biomedical processes and pharmaceutical applications. Small beads (<300 µm) offer distinct advantages, mainly due to improved mass transfer and mechanical strength. Here, we describe, for the first time, the encapsulation of human-bone-marrow-derived mesenchymal stem cells (hBM-MSCs) in small-sized microspheres, using one-step emulsification by internal gelation. Small (127−257 µm) high-mannuronic-alginate microspheres were prepared at high agitation rates (800−1000 rpm), enabling control over the bead size and shape. The average viability of encapsulated hBM-MSCs after 2 weeks was 81 ± 4.3% for the higher agitation rates. hBM-MSC-loaded microspheres seeded within a glycosaminoglycan (GAG) analogue, which was previously proposed as a mechanically equivalent implant for degenerate discs, kept their viability, sphericity, and integrity for at least 6 weeks. A preliminary in vivo study of hBM-MSC-loaded microspheres implanted (via a GAG-analogue hydrogel) in a rat injured intervertebral disc model demonstrated long-lasting viability and biocompatibility for at least 8 weeks post-implantation. The proposed method offers an effective and reproducible way to maintain long-lasting viability in vitro and in vivo. This approach not only utilizes the benefits of a simple, mild, and scalable method, but also allows for the easy control of the bead size and shape by the agitation rate, which, overall, makes it a very attractive platform for regenerative-medicine applications.

Advances in Head and Neck Cancer Pain

Head and neck cancer (HNC) affects over 890,000 people annually worldwide and has a mortality rate of 50%. Aside from poor survival, HNC pain impairs eating, drinking, and talking in patients, severely reducing quality of life. Different pain phenotype in patients (allodynia, hyperalgesia, and spontaneous pain) results from a combination of anatomical, histopathological, and molecular differences between cancers. Poor pathologic features (e.g., perineural invasion, lymph node metastasis) are associated with increased pain. The use of syngeneic/immunocompetent animal models, as well as a new mouse model of perineural invasion, provides novel insights into the pathobiology of HNC pain. Glial and immune modulation of the tumor microenvironment affect not only cancer progression but also pain signaling. For example, Schwann cells promote cancer cell proliferation, migration, and secretion of nociceptive mediators, whereas neutrophils are implicated in sex differences in pain in animal models of HNC. Emerging evidence supports the existence of a functional loop of cross-activation between the tumor microenvironment and peripheral nerves, mediated by a molecular exchange of bioactive contents (pronociceptive and protumorigenic) via paracrine and autocrine signaling. Brain-derived neurotrophic factor, tumor necrosis factor α, legumain, cathepsin S, and A disintegrin and metalloprotease 17 expressed in the HNC microenvironment have recently been shown to promote HNC pain, further highlighting the importance of proinflammatory cytokines, neurotrophic factors, and proteases in mediating HNC-associated pain. Pronociceptive mediators, together with nerve injury, cause nociceptor hypersensitivity. Oncogenic, pronociceptive mediators packaged in cancer cell-derived exosomes also induce nociception in mice. In addition to increased production of pronociceptive mediators, HNC is accompanied by a dampened endogenous antinociception system (e.g., downregulation of resolvins and µ-opioid receptor expression). Resolvin treatment or gene delivery of µ-opioid receptors provides pain relief in preclinical HNC models. Collectively, recent studies suggest that pain and HNC progression share converging mechanisms that can be targeted for cancer treatment and pain management.

Uncovering the RNA-binding protein landscape in the pluripotency network of human embryonic stem cells

Embryonic stem cell (ESC) self-renewal and cell fate decisions are driven by a broad array of molecular signals. While transcriptional regulators have been extensively studied in human ESCs (hESCs), the extent to which RNA-binding proteins (RBPs) contribute to human pluripotency remains unclear. Here, we carry out a proteome-wide screen and identify 810 proteins that bind RNA in hESCs. We reveal that RBPs are preferentially expressed in hESCs and dynamically regulated during early stem cell differentiation. Notably, many RBPs are affected by knockdown of OCT4, a master regulator of pluripotency, several dozen of which are directly targeted by this factor. Using cross-linking and immunoprecipitation (CLIP-seq), we find that the pluripotency-associated STAT3 and OCT4 transcription factors interact with RNA in hESCs and confirm the binding of STAT3 to the conserved NORAD long-noncoding RNA. Our findings indicate that RBPs have a more widespread role in human pluripotency than previously appreciated.

Upregulation of RET induces perineurial invasion of pancreatic adenocarcinoma

Tumor spread along nerves, a phenomenon known as perineurial invasion, is common in various cancers including pancreatic ductal adenocarcinoma (PDAC). Neural invasion is associated with poor outcome, yet its mechanism remains unclear. Using the transgenic Pdx-1-Cre/KrasG12D /p53R172H (KPC) mouse model, we investigated the mechanism of neural invasion in PDAC. To detect tissue-specific factors that influence neural invasion by cancer cells, we characterized the perineurial microenvironment using a series of bone marrow transplantation (BMT) experiments in transgenic mice expressing single mutations in the Cx3cr1, GDNF and CCR2 genes. Immunolabeling of tumors in KPC mice of different ages and analysis of human cancer specimens revealed that RET expression is upregulated during PDAC tumorigenesis. BMT experiments revealed that BM-derived macrophages expressing the RET ligand GDNF are highly abundant around nerves invaded by cancer. Inhibition of perineurial macrophage recruitment, using the CSF-1R antagonist GW2580 or BMT from CCR2-deficient donors, reduced perineurial invasion. Deletion of GDNF expression by perineurial macrophages, or inhibition of RET with shRNA or a small-molecule inhibitor, reduced perineurial invasion in KPC mice with PDAC. Taken together, our findings show that RET is upregulated during pancreas tumorigenesis and its activation induces cancer perineurial invasion. Trafficking of BM-derived macrophages to the perineurial microenvironment and secretion of GDNF are essential for pancreatic cancer neural spread.

Prognostic Performance of Current Stage III Oral Cancer Patients After Curative Intent Resection: Evidence to Support a Revision of the American Joint Committee on Cancer Staging System

BACKGROUND

The American Joint Committee on Cancer (AJCC) stage III classification of oral cavity squamous cell carcinoma (OCSCC) represents a heterogeneous group of patients with early local disease with regional metastases (T1N1 and T2N1) and advanced local disease with or without regional metastasis (T3N0 and T3N1).

OBJECTIVE

The aim of this study was to evaluate prognostic heterogeneity in the stage III category.

METHODS AND PATIENTS

An international retrospective multicenter study of 1815 patients who were treated for OCSCC from 2003 to 2011.

RESULTS

Kaplan-Meier survival analysis and multivariate models of stage III patients revealed better overall survival (OS; HR 2.12, 95 % CI 1.03-4.15; p = 0.01) and disease-specific survival (DSS; HR 1.7, 95 % CI 1.16-4.12; p = 0.04) rates for patients with T1-2N1/T3N0 disease than for patients with T3N1 disease. The outcomes of patients with T3N1 and stage IVa disease were similar (p = 0.89 and p = 0.78 for OS and DSS, respectively). Modifying stage classification by transferring the T3N1 category to the stage VIa group resulted in a better prognostic performance [Harrell's concordance index, C index 0.76; Akaike's Information Criterion (AIC) 4131.6] compared with the AJCC 7th edition staging system (C index 0.65; AIC 4144.9) for OS. When DSS was assessed, the suggested staging system remained the best performing model (C index 0.71; AIC 1061.3) compared with the current AJCC 7th edition staging (C index 0.64; AIC 1066.2).

CONCLUSIONS

The prognosis of T3N1 and stage IVa disease are similar in OCSCC, suggesting that these categories could be combined in future revisions of the nodal staging system to enhance prognostic accuracy.

Macrophages mediate gemcitabine resistance of pancreatic adenocarcinoma by upregulating cytidine deaminase

Resistance to pharmacologic agents used in chemotherapy is common in most human carcinomas, including pancreatic ductal adenocarcinoma (PDA), which is resistant to almost all drugs, including gemcitabine, a nucleoside analog used as a first-line treatment. Poor survival rates of PDA patients have, therefore, not changed much over 4 decades. Recent data indicated that tumor-associated macrophages (TAMs), which are abundant in the microenvironment of several tumors, including PDA, secrete pro-tumorigenic factors that contribute to cancer progression and dissemination. In this study, we show for the first time that TAMs can also induce chemoresistance of PDA by reducing gemcitabine-induced apoptosis. Macrophages co-cultured with cancer cells or TAM-conditioned medium significantly reduced apoptosis and activation of the caspase-3 pathway during gemcitabine treatment. In vivo PDA models of mice, which have reduced macrophage recruitment and activation, demonstrated improved response to gemcitabine compared with controls. Similarly, inhibition of monocytes/macrophages trafficking by a CSF1-receptor antagonist GW2580 augmented the effect of gemcitabine in a transgenic mouse PDA model that was resistant to gemcitabine alone. Analysis of multiple proteins involved in gemcitabine delivery and metabolism revealed that TAMs induced upregulation of cytidine deaminase (CDA), the enzyme that metabolizes the drug following its transport into the cell. Decreasing CDA expression by PDA cells blocked the protective effect of TAMs against gemcitabine. These results provide the first evidence of a paracrine effect of TAMs, which mediates acquired resistance of cancer cells to chemotherapy. Modulation of macrophage trafficking or inhibition of CDA may offer a new strategy for augmenting the response of PDA to chemotherapy.

Sources and derivation of human embryonic stem cells

Human embryonic stem cells (hESCs) are pluripotent cells derived from the inner cell mass (ICM) of the developing embryo. hESCs culture as cell lines in vitro and possess great potential in such research fields as developmental biology and cell-based therapy, as well as such industrial purposes as drug screening and toxicology. When ESCs were first derived by Thomson and colleagues, traditional methods of immunostaining and culturing, using primary mouse embryonic fibroblasts and medium supplemented by serum were used. Considerable efforts have since led to improved methods for isolating new lines in defined and reproducible conditions. This chapter discusses sources for embryos for ESC isolation, commonly used methods for deriving hESC lines, and a number of possible culture systems.

Efficient engineering of vascularized ectopic bone from human embryonic stem cell-derived mesenchymal stem cells

Human mesenchymal stem cells (hMSCs) can be derived from various adult and fetal tissues. However, the quality of tissues for the isolation of adult and fetal hMSCs is donor dependent with a nonreproducible yield. In addition, tissue engineering and cell therapy require large-scale production of a pure population of lineage-restricted stem cells that can be easily induced to differentiate into a specific cell type. Therefore, human embryonic stem cells (hESCs) can provide an alternative, plentiful source for generation of reproducible hMSCs. We have developed efficient differentiation protocols for derivation of hMSCs from hESCs, including coculture with murine OP9 stromal cells and feeder layer-free system. Our protocols have resulted in the generation of up to 49% of hMSCs, which expressed CD105, CD90, CD29, and CD44. The hMSCs exhibited high adipogenic, chondrocytic, and osteogenic differentiation in vitro. The latter correlated with osteocalcin secretion and vascular endothelial growth factor (VEGF) production by the differentiating hMSCs. hMSC-derived osteoblasts further differentiated and formed ectopic bone in vivo, and induced the formation of blood vessels in Matrigel implants. Our protocol enables generation of a purified population of hESC-derived MSCs, with the potential of differentiating into several mesodermal lineages, and particularly into vasculogenesis-inducing osteoblasts, which can contribute to the development of bone repair protocols.

Proteomics profiling of human embryonic stem cells in the early differentiation stage

The regulatory pathways responsible for maintaining human embryonic stem cells (hESCs) in an undifferentiated state have yet to be elucidated. Since these pathways are thought to be governed by complex protein cues, deciphering the changes that occur in the proteomes of the ESCs during differentiation is important for understanding the expansion and differentiation processes involved. In this study, we present the first quantitative comparison of the hESC protein profile in the undifferentiated and early differentiated states. We used iTRAQ (isobaric tags for relative and absolute quantification) labeling combined with two dimensional capillary chromatography coupled with tandem mass spectrometry (μLC-MS/MS) to achieve comparative proteomics of hESCs at the undifferentiated stage, and at 6, 48, and 72 h after initiation of differentiation. In addition, two dimensional electrophoresis (2-DE) was performed on differentiating hESCs at eleven points of time during the first 72 h of differentiation. The results indicate that during the first 48 h of hESC differentiation, many processes are initiated and are later reversed, including chromatin remodeling, heterochromatin spreading, a decrease in transcription and translation, a decrease in glycolytic proteins and cytoskeleton remodeling, and a decrease in focal and cell adhesion. Only 72 h after differentiation induction did the expression of the homeobox prox1 protein increase, indicating the beginning of developmental processes.

Multipotent vasculogenic pericytes from human pluripotent stem cells promote recovery of murine ischemic limb

BACKGROUND

Pericytes represent a unique subtype of microvessel-residing perivascular cells with diverse angiogenic functions and multilineage developmental features of mesenchymal stem cells. Although various protocols for derivation of endothelial and/or smooth muscle cells from human pluripotent stem cells (hPSC, either embryonic or induced) have been described, the emergence of pericytes in the course of hPSC maturation has not yet been elucidated.

METHODS AND RESULTS

We found that during hPSC development, spontaneously differentiating embryoid bodies give rise to CD105(+)CD90(+)CD73(+)CD31(-) multipotent clonogenic mesodermal precursors, which can be isolated and efficiently expanded. Isolated and propagated cells expressed characteristic pericytic markers, including CD146, NG2, and platelet-derived growth factor receptor β, but not the smooth muscle cell marker α-smooth muscle actin. Coimplantation of hPSC-derived endothelial cells with pericytes resulted in functional and rapid anastomosis to the murine vasculature. Administration of pericytes into immunodeficient mice with limb ischemia promoted significant vascular and muscle regeneration. At day 21 after transplantation, recruited hPSC pericytes were found incorporated into recovered muscle and vasculature.

CONCLUSIONS

Derivation of vasculogenic and multipotent pericytes from hPSC can be used for the development of vasculogenic models using multiple vasculogenic cell types for basic research and drug screening and can contribute to angiogenic regenerative medicine.

Molecular characterization and functional properties of cardiomyocytes derived from human inducible pluripotent stem cells

In view of the therapeutic potential of cardiomyocytes derived from induced pluripotent stem (iPS) cells (iPS-derived cardiomyocytes), in the present study we investigated in iPS-derived cardiomyocytes, the functional properties related to [Ca(2+) ](i) handling and contraction, the contribution of the sarcoplasmic reticulum (SR) Ca(2+) release to contraction and the b-adrenergic inotropic responsiveness. The two iPS clones investigated here were generated through infection of human foreskin fibroblasts (HFF) with retroviruses containing the four human genes: OCT4, Sox2, Klf4 and C-Myc. Our major findings showed that iPS-derived cardiomyocytes: (i) express cardiac specific RNA and proteins; (ii) exhibit negative force-frequency relations and mild (compared to adult) post-rest potentiation; (iii) respond to ryanodine and caffeine, albeit less than adult cardiomyocytes, and express the SR-Ca(2+) handling proteins ryanodine receptor and calsequestrin. Hence, this study demonstrates that in our cardiomyocytes clones differentiated from HFF-derived iPS, the functional properties related to excitation-contraction coupling, resemble in part those of adult cardiomyocytes.

Dynamic suspension culture for scalable expansion of undifferentiated human pluripotent stem cells

Human pluripotent (embryonic or induced) stem cells (hPSCs) have many potential applications, not only for research purposes but also for clinical and industrial uses. While culturing these cells as undifferentiated lines, an adherent cell culture based on supportive layers or matrices is most often used. However, the use of hPSCs for industrial or clinical applications requires a scalable, reproducible and controlled process. Here we present a suspension culture system for undifferentiated hPSCs, based on a serum-free medium supplemented with interleukins and basic fibroblast growth factor, suitable for the mass production of these cells. The described system supports a suspension culture of hPSC lines, in both static and dynamic cultures. Results showed that hPSCs cultured with the described dynamic method maintained all hPSC features after 20 passages, including stable karyotype and pluripotency, and increased in cell numbers by 25-fold in 10 d. Thus, the described suspension method is suitable for large-scale culture of undifferentiated hPSCs.

Vegetarian diets in children and adolescents

A well-balanced vegetarian diet can provide for the needs of children and adolescents. However, appropriate caloric intake should be ensured and growth monitored. Particular attention should be paid to adequate protein intake and sources of essential fatty acids, iron, zinc, calcium, and vitamins B₁₂ and D. Supplementation may be required in cases of strict vegetarian diets with no intake of any animal products. Pregnant and nursing mothers should also be appropriately advised to ensure that the nutritional needs of the fetus and infant are adequately met. Recommendations are provided. Adolescents on restricted vegetarian or other such diets should be screened for eating disorders.

Establishing a dynamic process for the formation, propagation, and differentiation of human embryoid bodies

The promise of human embryonic stem cells (hESCs) to provide an unlimited supply of cells for cell therapy depends on the availability of a controllable bioprocess for their expansion and differentiation. We describe here a robust and well-defined scale up platform for human embryoid body (EB) formation, propagation, and differentiation. The efficacy of the dynamic process as compared to the static cultivation in Petri dishes was analyzed. Our optimized conditions include specific bioreactor and impeller type, seeding and propagation parameters, and scale up. Quantitative analyses of viable cell concentrations, apoptosis percentages, and EB yield revealed 6.7-fold enhancement in the generation of hESC-derived cells after 10 cultivation days. Other metabolic indices such as glucose consumption, lactic acid production and pH all pointed to efficient cell expansion in the dynamic cultures. The hydrodynamic conditions during seeding and cultivation were found to be crucial for the EB formation and propagation. The EBs' prearrangement in the static system and EB cultivation in the Glass Ball Impeller spinner flask resulted in high EB yield, a round homogenous shape, and the fastest growth rate. The appearance of representative genes of the three germ layers as well as primitive neuronal tube organization and blood vessel formation indicated that the initial developmental events in the human EBs are not interfered by the dynamic system. Furthermore, well developed endothelial networks and contracting EBs with functional cardiac muscle were also obtained after two cultivation weeks. Collectively, our study defines the technological platform for the controlled large-scale generation of hESC-derived cells for clinical and industrial applications.

Characterization of human PGD blastocysts with unbalanced chromosomal translocations and human embryonic stem cell line derivation?

Novel embryonic stem cell lines derived from embryos carrying structural chromosomal abnormalities obtained after preimplantation genetic diagnosis (PGD) are of interest to study in terms of the influence of abnormalities on further development. A total of 22 unbalanced blastocysts obtained after PGD were analysed for structural chromosomal defects. Morphological description and chromosomal status of these blastocysts was established and they were used to derive human embryonic stem cell (ESC) lines. An outgrowth of cells was observed for six blastocysts (6/22; 27%). For two blastocysts, the exact morphology was unknown since they were at early stage, and for four blastocysts, the inner cell mass was clearly visible. Fifteen blastocysts carried an unbalanced chromosomal defect linked to a reciprocal translocation, resulting in a positive outgrowth of cells for five blastocysts. One human ESC line was obtained from a blastocyst carrying a partial chromosome-21 monosomy and a partial chromosome-1 trisomy. Six blastocysts carried an unbalanced chromosomal defect linked to a Robertsonian translocation, and one showed a positive outgrowth of cells. One blastocyst carried an unbalanced chromosomal defect linked to an insertion and no outgrowth was observed. The efficiency of deriving human ESC lines with constitutional chromosomal disorders was low and probably depends on the initial morphological aspect of the blastocysts and/or the type of the chromosomal disorders.

1,4,5-Inositol trisphosphate-operated intracellular Ca(2+) stores and angiotensin-II/endothelin-1 signaling pathway are functional in human embryonic stem cell-derived cardiomyocytes

On the basis of previous findings suggesting that in human embryonic stem cell-derived cardiomyocytes (hESC-CM) the sarcoplasmic reticulum Ca(2+)-induced release of calcium machinery is either absent or immature, in the present study we tested the hypothesis that hESC-CM contain fully functional 1,4,5-inositol trisphosphate (1,4,5-IP(3))-operated intracellular Ca(2+) ([Ca(2+)](i)) stores that can be mobilized upon appropriate physiological stimuli. To test this hypothesis we investigated the effects of angiotensin-II (AT-II) and endothelin-1 (ET-1), which activate the 1,4,5-IP(3) pathway, on [Ca(2+)](i) transients and contractions in beating clusters of hESC-CM. Our major findings were that in paced hESC-CM both AT-II and ET-1 (10(-9) to 10(-7) M) increased the contraction amplitude and the maximal rates of contraction and relaxation. In addition, AT-II (10(-9) to 10(-7) M) increased the [Ca(2+)](i) transient amplitude. The involvement of 1,4,5-IP(3)-dependent intracellular Ca(2+) release in the inotropic effect of AT-II was supported by the findings that (a) hESC-CM express AT-II, ET-1, and 1,4,5-IP(3) receptors determined by immunofluorescence staining, and (b) the effects of AT-II were blocked by 2 microM 2-aminoethoxyphenyl borate (a 1,4,5-IP(3) receptor blocker) and U73122 (a phospholipase C blocker). In conclusion, these findings demonstrate for the first time that hESC-CM exhibit functional AT-II and ET-1 signaling pathways, as well as 1,4,5-IP(3)-operated releasable Ca(2+) stores.

X-inactivation reveals epigenetic anomalies in most hESC but identifies sublines that initiate as expected

The clinical and research value of human embryonic stem cells (hESC) depends upon maintaining their epigenetically naïve, fully undifferentiated state. Inactivation of one X chromosome in each cell of mammalian female embryos is a paradigm for one of the earliest steps in cell specialization through formation of facultative heterochromatin. Mouse ES cells are derived from the inner cell mass (ICM) of blastocyst stage embryos prior to X-inactivation, and cultured murine ES cells initiate this process only upon differentiation. Less is known about human X-inactivation during early development. To identify a human ES cell model for X-inactivation and study differences in the epigenetic state of hESC lines, we investigated X-inactivation in all growth competent, karyotypically normal, NIH approved, female hESC lines and several sublines. In the vast majority of undifferentiated cultures of nine lines examined, essentially all cells exhibit hallmarks of X-inactivation. However, subcultures of any hESC line can vary in X-inactivation status, comprising distinct sublines. Importantly, we identified rare sublines that have not yet inactivated Xi and retain competence to undergo X-inactivation upon differentiation. Other sublines exhibit defects in counting or maintenance of XIST expression on Xi. The few hESC sublines identified that have not yet inactivated Xi may reflect the earlier epigenetic state of the human ICM and represent the most promising source of NIH hESC for study of human X-inactivation. The many epigenetic anomalies seen indicate that maintenance of fully unspecialized cells, which have not formed Xi facultative heterochromatin, is a delicate epigenetic balance difficult to maintain in culture.

A pure population of ectodermal cells derived from human embryonic stem cells

Embryonic stem (ES) cells represent a unique cellular model to recapitulate in vitro early steps of embryonic development and an unlimited cellular source in therapy for many diseases, as well as targets for drug discovery and toxicology screens. Although previous studies have reported epidermal differentiation of mouse and human embryonic stem (huES) cells, the heterogeneity of the resulting cell culture impairs the evaluation of differentiated cells for cell therapy. We report here the reproducible isolation of a homogenous ectodermal cell population, IT1, from human ES cells. Like primary cells, IT1 cells remain homogenous over 15 passages, expand up to 60 population doublings, and then die through senescence. Accordingly, IT1 cells display a normal karyotype and a somatic cell cycle kinetics and do not produce teratoma in nude mice. The production of K14-expressing epithelial cells driven by p63 expression strengthens the ectodermal nature of IT1 cells. Since IT1 can be isolated from different huES cell lines, it may provide a ready source of ectodermal progenitors for the development of a toxicology cell model, new-drug-screening strategies, and cell therapy transplantation.

Characterization of human embryonic stem cell lines by the International Stem Cell Initiative

The International Stem Cell Initiative characterized 59 human embryonic stem cell lines from 17 laboratories worldwide. Despite diverse genotypes and different techniques used for derivation and maintenance, all lines exhibited similar expression patterns for several markers of human embryonic stem cells. They expressed the glycolipid antigens SSEA3 and SSEA4, the keratan sulfate antigens TRA-1-60, TRA-1-81, GCTM2 and GCT343, and the protein antigens CD9, Thy1 (also known as CD90), tissue-nonspecific alkaline phosphatase and class 1 HLA, as well as the strongly developmentally regulated genes NANOG, POU5F1 (formerly known as OCT4), TDGF1, DNMT3B, GABRB3 and GDF3. Nevertheless, the lines were not identical: differences in expression of several lineage markers were evident, and several imprinted genes showed generally similar allele-specific expression patterns, but some gene-dependent variation was observed. Also, some female lines expressed readily detectable levels of XIST whereas others did not. No significant contamination of the lines with mycoplasma, bacteria or cytopathic viruses was detected.

Differentiation in vivo of cardiac committed human embryonic stem cells in postmyocardial infarcted rats

Human embryonic stem (HES) cells can give rise to cardiomyocytes in vitro. However, whether undifferentiated HES cells also feature a myocardial regenerative capacity after in vivo engraftment has not been established yet. We compared two HES cell lines (HUES-1 and I6) that were specified toward a cardiac lineage by exposure to bone morphogenetic protein-2 (BMP2) and SU5402, a fibroblast growth factor receptor inhibitor. Real-time polymerase chain reaction (PCR) revealed that the cardiogenic inductive factor turned on expression of mesodermal and cardiac genes (Tbx6, Isl1, FoxH1, Nkx2.5, Mef2c, and alpha-actin). Thirty immunosuppressed rats underwent coronary artery ligation and, 2 weeks later, were randomized and received in-scar injections of either culture medium (controls) or BMP2 (+/-SU5402)-treated HES cells. After 2 months, human cells were detected by anti-human lamin immunostaining, and their cardiomyocytic differentiation was evidenced by their expression of cardiac markers by reverse transcription-PCR and immunofluorescence using an anti-beta myosin antibody. No teratoma was observed in hearts or any other organ of the body. The ability of cardiac-specified HES cells to differentiate along the cardiomyogenic pathway following transplantation into infarcted myocardium raises the hope that these cells might become effective candidates for myocardial regeneration.

Feeder-layer free culture system for human embryonic stem cells

Human embryonic stem cells (hESCs) are pluripotent stem cells derived from the inner cell mass of the blastocyst. Due to their unique properties, hESCs might be used for research fields such as self-renewal, specific lineage differentiation, human developmental biology, and teratology. hESCs also have outstanding potential to serve for clinical purposes as a source for cell-based therapies. Traditionally, these cells are cultured and derived with mouse embryonic fibroblast as supportive layer, using a medium supplemented with fetal bovine serum. Future industrial and clinical implementation of hESCs will require the use of a defined medium and an animal-free culture method that will prevent their possible exposure to animal pathogens. This chapter discusses the advancements in the development of methods for the defined culture of hESCs and describes a simple method for animals serum-free and feeder layer-free culture of hESCs.

Human oligodendrocytes derived from embryonic stem cells: Effect of noggin on phenotypic differentiation in vitro and on myelination in vivo

In attempts to produce mature oligodendrocytes from human embryonic stem (huES) cells, we searched conditions inducing transcription factors Olig1/2, as well as Nkx2.2 and Sox10, which are needed for maturation. This was obtained by retinoic acid treatment followed by noggin, an antagonist of bone morphogenetic proteins (BMPs). We found that retinoic acid induces BMPs in huES cells. Addition of noggin at a specific step was essential to form numerous mature oligodendrocytes with ramified branches and producing myelin basic protein (MBP). We describe a procedure converting huES cells into enriched populations of oligodendrocyte precursors that can be expanded and passaged repeatedly and subsequently differentiated into mature cells. Transplantation of such precursors showed that pretreatment by noggin markedly stimulates their capacity to myelinate in the brain of MBP-deficient shiverer mice in organotypic cultures and in living animals. Arrays of numerous long MBP+ fibers were generated over extended areas in the brain, with evidence of cell migration after transplantation and with formation of compact myelin sheaths.

Sources, Derivation, and Culture of Human Embryonic Stem Cells

Human embryonic stem cells (hESCs) are immortal cells capable of perpetual self-renewal in culture while maintaining their undifferentiated state, high telomerase activity, normal karyotype, and specific pattern expression of embryonic surface markers and pluripotent transcription factors such as Oct-4 and Nanog. Since their first derivation in 1998, hundreds of hESC lines have been derived and characterized. Normal surplus embryos from IVF programs are the main source for the derivation of hESC lines but cell lines from poor-quality discarded embryos or embryos carrying genetic defects following preimplantation genetic diagnosis were also isolated. Such isolation is usually accomplished by either mechanical or immunosurgical removal of the trophectoderm and culture of the inner cell mass on inactivated feeder cells. In light of the future need for clinical-grade cells, the subject of defining specific culture conditions has been addressed widely. Indeed, derivation and maintenance of hESCs without feeder cells and in media free of animal products have been attained recently. This well-defined culture system may facilitate research and clinical applications, and use the remarkable potential of these exceptional cells to its fullest in both the laboratory and the clinic.

Derivation and maintenance of human embryonic stem cells

Since their derivation in 1998, human embryonic stem cells (hESCs) have been the center of tremendous scientific efforts in improve the existing methodologies for their isolation and maintenance to exhaust the potential use of these unique cells in cell-based therapy and developmental research. To date, there are more than 50 reported well-characterized hESC lines worldwide. hESCs are traditionally isolated from the blastocysts on mouse embryonic fibroblasts. The most used method for isolating the inner cell mass from the human blastocyst is immunosurgery. This chapter focuses on the basic methods for the derivation and maintenance of hESC lines.

Maintenance of human embryonic stem cells in animal serum- and feeder layer-free culture conditions

The availability of human embryonic stem cells (hESCs) reflects their outstanding potential for research areas such as human developmental biology, teratology, and cell-based therapies. To allow their continuous growth as undifferentiated cells, isolation and culturing were traditionally conducted on mouse embryonic fibroblast feeder layers, using medium supplemented with fetal bovine serum. However, these conditions allow possible exposure of the cells to animal pathogens. Because both research and future clinical application require an animal-free and well-defined culture system for hESCs, these conventional conditions would prevent the use of hESCs in human therapy. This chapter describes optional culture conditions based on either animal-free or feeder-free culture methods for hESCs.

Feeder-free culture of human embryonic stem cells

In addition to their contribution to research fields such as early human development, self-renewal, and differentiation mechanisms, human embryonic stem cells (hESCs) may serve as a tool for drug testing and for the study of cell-based therapies. Traditionally, these cells have been cultured with mouse embryonic fibroblast (MEF) feeder layers, which allow their continuous growth in an undifferentiated state. However, for future clinical applications, hESCs should be cultured under defined conditions, preferably in a xeno-free culture system, where exposure to animal pathogens is prevented. To this end, different culture methods for hESCs, based on serum replacement and free of supportive cell layers, were developed. This chapter discusses a simple, feeder-free culture system on the basis of medium supplemented with transforming growth factor beta1 (TGFbeta1), basic fibroblast growth factor (bFGF) and fibronectin as matrix.

Functional properties of human embryonic stem cell-derived cardiomyocytes: intracellular Ca2+ handling and the role of sarcoplasmic reticulum in the contraction

Since cardiac transplantation is limited by the small availability of donor organs, regeneration of the diseased myocardium by cell transplantation is an attractive therapeutic modality. To determine the compatibility of human embryonic stem cell-derived cardiomyocytes (hESC-CMs) (7 to 55 days old) with the myocardium, we investigated their functional properties regarding intracellular Ca2+ handling and the role of the sarcoplasmic reticulum in the contraction. The functional properties of hESC-CMs were investigated by recording simultaneously [Ca2+]i transients and contractions. Additionally, we performed Western blot analysis of the Ca2+-handling proteins SERCA2, calsequestrin, phospholamban, and Na+/Ca2+ exchanger (NCX). Our major findings are, first, that hESC-CMs displayed temporally related [Ca2+]i transients and contractions, negative force-frequency relations, and lack of post-rest potentiation. Second, ryanodine, thapsigargin, and caffeine did not affect the [Ca2+]i transient and contraction, indicating that at this developmental stage, contraction depends on transsarcolemmal Ca2+ influx rather than on sarcoplasmic reticulum Ca2+ release. Third, in agreement with the notion that a voltage-dependent Ca2+ current is present in hESC-CMs and contributes to the mechanical function, verapamil completely blocked contraction. Fourth, whereas hESC-CMs expressed SERCA2 and NCX at levels comparable to those of the adult porcine myocardium, calsequestrin and phospholamban were not expressed. Our study shows for the first time that functional properties related to intracellular Ca2+ handling of hESC-CMs differ markedly from the adult myocardium, probably due to immature sarcoplasmic reticulum capacity.

Molecular analysis of cardiomyocytes derived from human embryonic stem cells

During early embryogenesis, the cardiovascular system is the first system to be established and is initiated by a process involving the hypoblastic cells of the primitive endoderm. Human embryonic stem (hES) cells provide a model to investigate the early developmental stages of this system. When removed from their feeder layer, hESC create embryoid bodies (EB) which, when plated, develop areas of beating cells in 21.5% of the EB. These spontaneously contracting cells were demonstrated using histology, immunostaining and reverse transcription-polymerase chain reaction (RT-PCR), to possess morphological and molecular characteristics consistent with cardiomyocytic phenotypes. In addition, the expression pattern of specific cardiomyocytic genes in human EB (hEB) was demonstrated and analyzed for the first time. GATA-4 is the first gene to be expressed in 6-day-old EB. Alpha cardiac actin and atrial natriuretic factor are expressed in older hEB at 10 and 20 days, respectively. Light chain ventricular myosin (MLC-2V) was expressed only in EB with beating areas and its expression increased with time. Alpha heavy chain myosin (alpha-MHC) expression declined in the pulsating hEB with time, in contrast to events in EB derived from mice. We conclude that human embryonic stem cells can provide a useful tool for research on embryogenesis in general and cardiovascular development in particular.

No evidence for infection of human embryonic stem cells by feeder cell-derived murine leukemia viruses

Until recently, culture and expansion of nondifferentiated human embryonic stem cells (hESCs) depended on coculture with murine embryonic fibroblasts. Because mice are known to harbor a variety of pathogens, such culture conditions implicate the risk of xenozoonoses. Among these pathogens, endogenous retroviruses, including murine leukemia viruses (MuLVs), are of special importance. It is well known that some strains cause pathogenic (e.g., leukemic) effects and that xenotropic, polytropic, and amphotropic MuLVs are able to infect human cells. In view of potential clinical applications of hESC lines, it is therefore imperative to investigate potential infection of hESCs by mouse feeder cell-derived viruses. As a first step towards a comprehensive infection risk assessment, we have analyzed embryonic fibroblasts derived from different mouse strains for expression and release of xenotropic, polytropic, and amphotropic MuLVs. Moreover, several hESC lines have been investigated for expression of specific receptors for xenotropic/polytropic MuLVs, as well as for MuLV infection and expression. Evidence for expression of humantropic MuLVs was found in cultures of mouse embryonic fibroblasts (MEFs). Moreover, expression of specific receptors for xenotropic/ polytropic MuLV on human HEK293 and hESC lines and infection after coculture with an MuLV-producing mink cell line could be demonstrated. In contrast, no evidence of MuLV transmission from MEFs to human HEK293 cells or to the hESC lines I-3, I-6, I-8, and H-9 has been obtained. Our results suggest that recently established hESC lines are free of MuLV infections despite long-term close contact with MEFs.

Differences between human and mouse embryonic stem cells

We compared gene expression profiles of mouse and human ES cells by immunocytochemistry, RT-PCR, and membrane-based focused cDNA array analysis. Several markers that in concert could distinguish undifferentiated ES cells from their differentiated progeny were identified. These included known markers such as SSEA antigens, OCT3/4, SOX-2, REX-1 and TERT, as well as additional markers such as UTF-1, TRF1, TRF2, connexin43, and connexin45, FGFR-4, ABCG-2, and Glut-1. A set of negative markers that confirm the absence of differentiation was also developed. These include genes characteristic of trophoectoderm, markers of germ layers, and of more specialized progenitor cells. While the expression of many of the markers was similar in mouse and human cells, significant differences were found in the expression of vimentin, beta-III tubulin, alpha-fetoprotein, eomesodermin, HEB, ARNT, and FoxD3 as well as in the expression of the LIF receptor complex LIFR/IL6ST (gp130). Profound differences in cell cycle regulation, control of apoptosis, and cytokine expression were uncovered using focused microarrays. The profile of gene expression observed in H1 cells was similar to that of two other human ES cell lines tested (line I-6 and clonal line-H9.2) and to feeder-free subclones of H1, H7, and H9, indicating that the observed differences between human and mouse ES cells were species-specific rather than arising from differences in culture conditions.

The effect of spironolactone, cilazapril and their combination on albuminuria in patients with hypertension and diabetic nephropathy is independent of blood pressure reduction: a randomized controlled study

OBJECTIVE

The effect of spironolactone, cilazapril and their combination on albuminuria was examined in a randomized prospective study in female patients with diabetes and hypertension.

PATIENTS AND METHODS

Sixty female diabetic patients aged 45-70 years with blood pressure (BP) 140-180/90-110 mmHg, serum creatinine (sCr) < or = 160 micro mol/l, HbA(1c) < or = 10%, and albuminuria were treated by atenolol 12.5-75 mg/d and hydrochlorothiazide 6.25-25 mg/d. Titration-to-target helped to reach BP values < or = 135/85 mmHg in 46 patients after 12 weeks. These patients were randomized to spironolactone 100 mg/d or cilazapril 5 mg/d for 24 weeks. Then both groups received spironolactone 50 mg/d and cilazapril 2.5 mg/d for 24 weeks. BP was stabilized by tapering the dose of the initial agents. Urinary albumin/creatinine ratio (ACR), BP, K(+). sCr and HbA(1c) were assessed at baseline and at weeks 12, 16, 36 and 60.

RESULTS

The average BP at week 12 was 128 +/- 4/81 +/- 3 mmHg and remained constant, in both groups, throughout the study. ACR declined on spironolactone from a median value (range) of 452 (124-1571) to 216 (64-875) mg/g (P = 0.001), and on cilazapril to 302 (90-975) mg/g (P = 0.001). The difference between spironolactone and cilazapril was significant (P = 0.002). Combined treatment resulted in a further modest decline in ACR. Serum creatinine was unaltered by spironolactone and rose slightly (121 to 126 micro mol/l, P = 0.02) on cilazapril.

CONCLUSION

At the doses tested, spironolactone was superior to cilazapril in reducing albuminuria. Combined administration was more effective than either drug alone. These effects were independent of BP values. Hyperkalaemia was the main side-effect.

Derivation of a diploid human embryonic stem cell line from a mononuclear zygote

BACKGROUND

IVF occasionally produces aneuploid zygotes with one or three pronuclei (PN). Routinely, these zygotes are discarded. The aim of this work was to establish human embryonic stem cell (hESC) lines from blastocysts resulting from abnormal fertilization.

METHODS

Abnormally fertilized zygotes were cultured to the blastocyst stage and, following zona pellucida digestion, zona-free blastocysts were placed on a mouse feeder layer. Culture of hESCs was carried out as described earlier.

RESULTS

Six out of the nine developing blastocysts attached to the feeder layer. One hESC line, originating from a mononuclear zygote following ICSI, was successfully derived. This line displayed typical phenotype and embryonic surface markers, and exhibited the potential to develop into all three embryonic germ layers both in vitro (by embryoid body formation) and in vivo (teratoma generation). Genetic examination revealed normal diploid karyotype and heterozygotic appearance for metachromatic leukodystrophy (MLD).

CONCLUSION

This method, which requires neither immuno nor mechanical removal of the trophectoderm, may facilitate the derivation of hESC lines in general, and those from abnormal embryos in particular. Furthermore, it is shown that aneuploid zygotes can be used as a source for normal hESC derivation and hold the potential to generate aneuploid hESC lines for research purposes.

Gene expression in human embryonic stem cell lines: unique molecular signature

Human embryonic stem (huES) cells have the ability to differentiate into a variety of cell lineages and potentially provide a source of differentiated cells for many therapeutic uses. However, little is known about the mechanism of differentiation of huES cells and factors regulating cell development. We have used high-quality microarrays containing 16 659 seventy-base pair oligonucleotides to examine gene expression in 6 of the 11 available huES cell lines. Expression was compared against pooled RNA from multiple tissues (universal RNA) and genes enriched in huES cells were identified. All 6 cell lines expressed multiple markers of the undifferentiated state and shared significant homology in gene expression (overall similarity coefficient > 0.85).A common subset of 92 genes was identified that included Nanog, GTCM-1, connexin 43 (GJA1), oct-4, and TDGF1 (cripto). Gene expression was confirmed by a variety of techniques including comparison with databases, reverse transcriptase-polymerase chain reaction, focused cDNA microarrays, and immunocytochemistry. Comparison with published "stemness" genes revealed a limited overlap, suggesting little similarity with other stem cell populations. Several novel ES cell-specific expressed sequence tags were identified and mapped to the human genome. These results represent the first detailed characterization of undifferentiated huES cells and provide a unique set of markers to profile and better understand the biology of huES cells.

Feeder layer- and serum-free culture of human embryonic stem cells

In addition to their contribution to the research on early human development, human embryonic stem (hES) cells may also be used for cell-based therapies. Traditionally, these cells have been cultured on mouse embryonic fibroblast feeder layers, which allow their continuous growth in an undifferentiated state. However, the use of hES cells in human therapy requires an animal-free culture system, in which exposure to mouse retroviruses is avoided. In this study we present a novel feeder layer-free culture system for hES cells, based on medium supplemented with 15% serum replacement, a combination of growth factors including transforming growth factor beta1 (TGFbeta1), leukemia inhibitory factor, basic fibroblast growth factor, and fibronectin matrix. Human ES cells grown in these conditions maintain all ES cell features after prolonged culture, including the developmental potential to differentiate into representative tissues of the three embryonic germ layers, unlimited and undifferentiated proliferative ability, and maintenance of normal karyotype. The culture system presented here has two major advantages: 1) application of a well-defined culture system for hES cells and 2) reduced exposure of hES cells to animal pathogens. The feeder layer-free culture system reported here aims at facilitating research practices and providing a safer alternative for future clinical applications of hES cells.

Human feeder layers for human embryonic stem cells

Human embryonic stem (hES) cells hold great promise for future use in various research areas, such as human developmental biology and cell-based therapies. Traditionally, these cells have been cultured on mouse embryonic fibroblast (MEF) feeder layers, which permit continuous growth in an undifferentiated stage. To use these unique cells in human therapy, an animal-free culture system must be used, which will prevent exposure to mouse retroviruses. Animal-free culture systems for hES cells enjoy three major advantages in the basic culture conditions: 1). the ability to grow these cells under serum-free conditions, 2). maintenance of the cells in an undifferentiated state on Matrigel matrix with 100% MEF-conditioned medium, and 3). the use of either human embryonic fibroblasts or adult fallopian tube epithelial cells as feeder layers. In the present study, we describe an additional animal-free culture system for hES cells, based on a feeder layer derived from foreskin and a serum-free medium. In this culture condition, hES cells maintain all embryonic stem cell features (i.e., pluripotency, immortality, unlimited undifferentiated proliferation capability, and maintenance of normal karyotypes) after prolonged culture of 70 passages (>250 doublings). The major advantage of foreskin feeders is their ability to be continuously cultured for more than 42 passages, thus enabling proper analysis for foreign agents, genetic modification such as antibiotic resistance, and reduction of the enormous workload involved in the continuous preparation of new feeder lines.