Relationship Between Stage-specific Embryonic Antigen-4 and Anti-cancer Effects of Neoadjuvant Hormonal Therapy in Prostate Cancer

BACKGROUND/AIM

Stage-specific embryonic antigen-4 (SSEA-4) expression is associated with malignant aggressiveness and is useful as a marker for identifying cancer stem cells. Our aim was to assess the relationship between hormonal therapy and SSEA-4 expression in prostate cancer (PC).

MATERIALS AND METHODS

SSEA-4 expression in paired specimens from PC patients who underwent neoadjuvant hormonal therapy (NHT) and radical prostatectomy (60 pre-NHT specimens and 60 post-NHT specimens) was evaluated using immunohistochemistry. Proliferation index (PI) and apoptotic index (AI) were also evaluated.

RESULTS

Post-NHT tissues had significantly elevated SSEA-4 expression whereas anti-tumor effects of NHT were inversely correlated with SSEA-4 expression level. SSEA-4 expression in post-NHT tissues was significantly associated with biochemical recurrence-free survival. SSEA-4 expression in the post-NHT tissues was positively associated with PI and negatively done with AI.

CONCLUSION

SSEA-4 is a potential therapeutic target for limiting the malignant potential in hormone-naïve PC when considering the use of NHT.

Acidic Pre-Conditioning Enhances the Stem Cell Phenotype of Human Bone Marrow Stem/Progenitor Cells

A deeper understanding of the detailed mechanism of in vivo tissue healing is necessary for the development of novel regenerative therapies. Among several external factors, environmental pH is one of the crucial parameters that greatly affects enzyme activity and cellular biochemical reactions involving tissue repair and homeostasis. In this study, in order to analyze the microenvironmental conditions during bone healing, we first measured the pH in vivo at the bone healing site using a high-resolution fiber optic pH microsensor directly in femur defects and tooth extraction sockets. The pH was shown to decrease from physiological 7.4 to 6.8 during the initial two days of healing (inflammatory phase). In the same initial stages of the inflammatory phase of the bone healing process, mesenchymal stem cells (MSCs) are known to migrate to the healing site to contribute to tissue repair. Therefore, we investigated the effect of a short-term acidic (pH 6.8) pre-treatment on the stemness of bone marrow-derived MSCs (BMSCs). Interestingly, the results showed that pre-treatment of BMSCs with acidic pH enhances the expression of stem cell markers (OCT-4, NANOG, SSEA-4), as well as cell viability and proliferation. On the other hand, acidic pH decreased BMSC migration ability. These results indicate that acidic pH during the initial stages of bone healing is important to enhance the stem cell properties of BMSCs. These findings may enable the development of novel methods for optimization of stem cell function towards tissue engineering or regenerative medicine.

Changes of glycoconjugate expression profiles during early development

A variety of glycoconjugates, including glycosphingolipids (GSLs), expressed in mammalian tissues and cells were isolated and characterized in early biochemical studies. Later studies of virus-transformed fibroblasts demonstrated the association of GSL expression profiles with cell phenotypes. Changes of GSL expression profile were observed during mammalian embryogenesis. Cell surface molecules expressed on embryos in a stage-specific manner appeared to play key roles in regulation of cell-cell interaction and cell sorting during early development. Many mAbs showing stage-specific reactivity with mouse embryos were shown to recognize carbohydrate epitopes. Among various stage-specific embryonic antigens (SSEAs), SSEA-1 was found to react with neolacto-series GSL Le^x, while SSEA-3 and SSEA-4 reacted with globo-series Gb5 and monosialyl-Gb5, respectively. GSL expression during mouse early development was shown to shift rapidly from globo-series to neolacto/lacto-series, and then to ganglio-series. We found that multivalent Le^x caused decompaction of mouse embryos, indicating a functional role of Le^x epitope in the compaction process. Autoaggregation of mouse embryonal carcinoma (EC) F9 cells provided a useful model of the compaction process. We showed that Le^x-Le^x interaction, a novel type of molecular interavction termed carbohydrate-carbohydrate interaction (CCI), was involved in cell aggregation. Similar shifting of GSL expression profiles from globo-series and neolacto/lacto-series to ganglio-series was observed during differentiation of human EC cells and embryonic stem (ES) cells, reflecting the essential role of cell surface glycoconjugates in early development.

Differentiation of Human Dental Pulp Stem Cells into Dopaminergic Neuron-like Cells in Vitro

We investigated the potential of human dental pulp stem cells (hDPSCs) to differentiate into dopaminergic neurons in vitro as an autologous stem cell source for Parkinson's disease treatment. The hDPSCs were expanded in knockout-embryonic stem cell (KO-ES) medium containing leukemia inhibitory factor (LIF) on gelatin-coated plates for 3-4 days. Then, the medium was replaced with KO-ES medium without LIF to allow the formation of the neurosphere for 4 days. The neurosphere was transferred into ITS medium, containing ITS (human insulin-transferrin-sodium) and fibronectin, to select for Nestin-positive cells for 6-8 days. The cells were then cultured in N-2 medium containing basic fibroblast growth factor (FGF), FGF-8b, sonic hedgehog-N, and ascorbic acid on poly-l-ornithine/fibronectin-coated plates to expand the Nestin-positive cells for up to 2 weeks. Finally, the cells were transferred into N-2/ascorbic acid medium to allow for their differentiation into dopaminergic neurons for 10-15 days. The differentiation stages were confirmed by morphological, immunocytochemical, flow cytometric, real-time PCR, and ELISA analyses. The expressions of mesenchymal stem cell markers were observed at the early stages. The expressions of early neuronal markers were maintained throughout the differentiation stages. The mature neural markers showed increased expression from stage 3 onwards. The percentage of cells positive for tyrosine hydroxylase was 14.49%, and the amount was 0.526 ± 0.033 ng/mL at the last stage. hDPSCs can differentiate into dopaminergic neural cells under experimental cell differentiation conditions, showing potential as an autologous cell source for the treatment of Parkinson's disease.

Culture adaptation alters transcriptional hierarchies among single human embryonic stem cells reflecting altered patterns of differentiation

We have used single cell transcriptome analysis to re-examine the substates of early passage, karyotypically Normal, and late passage, karyotypically Abnormal (‘Culture Adapted’) human embryonic stem cells characterized by differential expression of the cell surface marker antigen, SSEA3. The results confirmed that culture adaptation is associated with alterations to the dynamics of the SSEA3(+) and SSEA3(-) substates of these cells, with SSEA3(-) Adapted cells remaining within the stem cell compartment whereas the SSEA3(-) Normal cells appear to have differentiated. However, the single cell data reveal that these substates are characterized by further heterogeneity that changes on culture adaptation. Notably the Adapted population includes cells with a transcriptome substate suggestive of a shift to a more naïve-like phenotype in contrast to the cells of the Normal population. Further, a subset of the Normal SSEA3(+) cells expresses genes typical of endoderm differentiation, despite also expressing the undifferentiated stem cell genes, POU5F1 (OCT4) and NANOG, whereas such apparently lineage-primed cells are absent from the Adapted population. These results suggest that the selective growth advantage gained by genetically variant, culture adapted human embryonic stem cells may derive in part from a changed substate structure that influences their propensity for differentiation.

A systemic evaluation of cardiac differentiation from mRNA reprogrammed human induced pluripotent stem cells

Genetically unmodified cardiomyocytes mandated for cardiac regenerative therapy is conceivable by “foot-print free” reprogramming of somatic cells to induced pluripotent stem cells (iPSC). In this study, we report generation of foot-print free hiPSC through messenger RNA (mRNA) based reprograming. Subsequently, we characterize cardiomyocytes derived from these hiPSC using molecular and electrophysiological methods to characterize their applicability for regenerative medicine. Our results demonstrate that mRNA-iPSCs differentiate ontogenetically into cardiomyocytes with increased expression of early commitment markers of mesoderm, cardiac mesoderm, followed by cardiac specific transcriptional and sarcomeric structural and ion channel genes. Furthermore, these cardiomyocytes stained positively for sarcomeric and ion channel proteins. Based on multi-electrode array (MEA) recordings, these mRNA-hiPSC derived cardiomyocytes responded predictably to various pharmacologically active drugs that target adrenergic, sodium, calcium and potassium channels. The cardiomyocytes responded chronotropically to isoproterenol in a dose dependent manner, inotropic activity of nifidipine decreased spontaneous contractions. Moreover, Sotalol and E-4031 prolonged QT intervals, while TTX reduced sodium influx. Our results for the first time show a systemic evaluation based on molecular, structural and functional properties of cardiomyocytes differentiated from mRNA-iPSC. These results, coupled with feasibility of generating patient-specific iPSCs hold great promise for the development of large-scale generation of clinical grade cardiomyocytes for cardiac regenerative medicine.

Continuous hypoxic culturing of human embryonic stem cells enhances SSEA-3 and MYC levels

Low oxygen tension (hypoxia) contributes critically to pluripotency of human embryonic stem cells (hESCs) by preventing spontaneous differentiation and supporting self-renewal. However, it is not well understood how hESCs respond to reduced oxygen availability and what are the molecular mechanisms maintaining pluripotency in these conditions. In this study we characterized the transcriptional and molecular responses of three hESC lines (H9, HS401 and HS360) on short (2 hours), intermediate (24 hours) and prolonged (7 days) exposure to low oxygen conditions (4% O₂). In response to prolonged hypoxia the expression of pluripotency surface marker SSEA-3 was increased. Furthermore, the genome wide gene-expression analysis revealed that a substantial proportion (12%) of all hypoxia-regulated genes in hESCs, were directly linked to the mechanisms controlling pluripotency or differentiation. Moreover, transcription of MYC oncogene was induced in response to continuous hypoxia. At the protein level MYC was stabilized through phosphorylation already in response to a short hypoxic exposure. Total MYC protein levels remained elevated throughout all the time points studied. Further, MYC protein expression in hypoxia was affected by silencing HIF2α, but not HIF1α. Since MYC has a crucial role in regulating pluripotency we propose that induction of sustained MYC expression in hypoxia contributes to activation of transcriptional programs critical for hESC self-renewal and maintenance of enhanced pluripotent state.

Ontological differences in first compared to third trimester human fetal placental chorionic stem cells

Human mesenchymal stromal/stem cells (MSC) isolated from fetal tissues hold promise for use in tissue engineering applications and cell-based therapies, but their collection is restricted ethically and technically. In contrast, the placenta is a potential source of readily-obtainable stem cells throughout pregnancy. In fetal tissues, early gestational stem cells are known to have advantageous characteristics over neonatal and adult stem cells. Accordingly, we investigated whether early fetal placental chorionic stem cells (e-CSC) were physiologically superior to their late gestation fetal chorionic counterparts (l-CSC). We showed that e-CSC shared a common phenotype with l-CSC, differentiating down the osteogenic, adipogenic and neurogenic pathways, and containing a subset of cells endogenously expressing NANOG, SOX2, c-MYC, and KLF4, as well as an array of genes expressed in pluripotent stem cells and primordial germ cells, including CD24, NANOG, SSEA4, SSEA3, TRA-1-60, TRA-1-81, STELLA, FRAGILIS, NANOS3, DAZL and SSEA1. However, we showed that e-CSC have characteristics of an earlier state of stemness compared to l-CSC, such as smaller size, faster kinetics, uniquely expressing OCT4A variant 1 and showing higher levels of expression of NANOG, SOX2, c-MYC and KLF4 than l-CSC. Furthermore e-CSC, but not l-CSC, formed embryoid bodies containing cells from the three germ layer lineages. Finally, we showed that e-CSC demonstrate higher tissue repair in vivo; when transplanted in the osteogenesis imperfecta mice, e-CSC, but not l-CSC increased bone quality and plasticity; and when applied to a skin wound, e-CSC, but not l-CSC, accelerated healing compared to controls. Our results provide insight into the ontogeny of the stemness phenotype during fetal development and suggest that the more primitive characteristics of early compared to late gestation fetal chorionic stem cells may be translationally advantageous.

Infantile haemangioma expresses embryonic stem cell markers

BACKGROUND

The origin of infantile haemangioma (IH) remains enigmatic. A primitive mesodermal phenotype origin of IH with the ability to differentiate down erythropoietic and terminal mesenchymal lineages has recently been demonstrated.

AIMS

To investigate the expression of human embryonic stem cell (hESC) markers in IH and to determine whether IH-derived cells have the functional capacity to form teratoma in vivo.

METHODS

Immunohistochemical staining and quantitative reverse transcription PCR were used to investigate the expression of hESC markers in IH biopsies. The ability of cells derived from proliferating IH to form teratomas in a mouse xenograft model was investigated.

RESULTS

The hESC markers, Oct-4, STAT-3 and stage-specific embryonic antigen 4 were collectively expressed on the endothelium of proliferating IH lesions, whereas Nanog was not. Nanog was expressed by cells in the interstitium and these cells did not express Oct-4, stage-specific embryonic antigen 4 or STAT-3. Proliferating IH-derived cells were unable to form teratomas in severely compromised immunodeficient/non-obese diabetic mice.

CONCLUSION

The novel expression of hESC on two different populations of cells in proliferating IH and their inability to form teratomas in vivo infer the presence of a primitive cellular origin for IH downstream from hESC.

Stable expression of FoxA1 promotes pluripotent P19 embryonal carcinoma cells to be neural stem-like cells

FoxA1 belongs to the fork head/winged-helix transcription factor family and participates in stimulating neuronal differentiation of pluripotent stem cells at early stages. To explore the biological roles of FoxA1 during this process, the stable expression of a GFP-FoxA1 fusion protein was established in P19 pluripotent embryonal carcinoma cells. Although they still express pluripotency-related transcription factors such as Oct4, Nanog, and Sox2, the generated P19 GFPFoxA1 cells exhibited a decreased activity of alkaline phosphatase and an increased expression of SSEA-3 compared with P19 cells. Elevated levels of nestin expression and prominin-1+ populations were observed in P19 GFPFoxA1 cells, implicating that the stable expression of FoxA1 promoted P19 cells to gain partial characteristics of neural stem cells. Furthermore, the promoter of nestin was confirmed to be bound and activated by FoxA1 directly. The expression of neuron-specific marker tubulin betaIII also existed in P19 GFPFoxA1 cells. P19 GFPFoxA1 cells showed an earlier onset of differentiation during RA-induced neuronal differentiation, evidenced by a more rapid change on the Nanog decrease and the tubulin betaIII increase. Thus, overexpression of FoxA1 alone may promote pluripotent P19 cells to become neural stem-like cells.