ATP autocrine/paracrine signaling induces calcium oscillations and NFAT activation in human mesenchymal stem cells.

Human bone marrow-derived mesenchymal stem cells (hMSCs) have the potential to differentiate into several types of cells. Calcium ions (Ca(2+)) play an important role in the differentiation and proliferation of hMSCs. We have demonstrated that spontaneous [Ca(2+)](i) oscillations occur without agonist stimulation in hMSCs. However, the precise mechanism of its generation remains unclear. In this study, we investigated the mechanism and role of spontaneous [Ca(2+)](i) oscillations in hMSCs and found that IP(3)-induced Ca(2+) release is essential for spontaneous [Ca(2+)](i) oscillations. We also found that an ATP autocrine/paracrine signaling pathway is involved in the oscillations. In this pathway, an ATP is secreted via a hemi-gap-junction channel; it stimulates the P(2)Y(1) receptors, resulting in the activation of PLC-beta to produce IP(3). We were able to pharmacologically block this pathway, and thereby to completely halt the [Ca(2+)](i) oscillations. Furthermore, we found that [Ca(2+)](i) oscillations were associated with NFAT translocation into the nucleus in undifferentiated hMSCs. Once the ATP autocrine/paracrine signaling pathway was blocked, it was not possible to detect the nuclear translocation of NFAT, indicating that the activation of NFAT is closely linked to [Ca(2+)](i) oscillations. As the hMSCs differentiated to adipocytes, the [Ca(2+)](i) oscillations disappeared and the translocation of NFAT ceased. These results provide new insight into the molecular and physiological mechanism of [Ca(2+)](i) oscillations in undifferentiated hMSCs.

Na+/K+ ATPase and its functional coupling with Na+/Ca2+ exchanger in mouse embryonic stem cells during differentiation into cardiomyocytes.

Cardiomyocytes derived from mouse embryonic stem (mES) cells have been demonstrated to exhibit a time-dependent expression of ion channels and signal transduction pathways in electrophysiological studies. However, ion transporters, such as Na+/K+ ATPase (Na+ pump) or Na+/Ca2+ exchanger, which play crucial roles for cardiac function, have not been well studied in this system. In this study, we investigated the functional expression of Na+/K+ ATPase and Na+/Ca2+ exchanger in mES cells during in vitro differentiation into cardiomyocytes, as well as the functional coupling between the two transporters. By measuring [Na+]i and Na+ pump current (Ip), it was shown that an ouabain-high sensitive Na+/K+ ATPase was expressed functionally in undifferentiated mES cells and these activities increased during a time course of differentiation. Using RT-PCR, the expression of mRNA for alpha1-subunit and alpha3-subunit of the Na+/K+ ATPase could be detected in both undifferentiated mES cells and derived cardiomyocytes. In contrast alpha2-subunit mRNA could be detected only in derived cardiomyocytes but not in undifferentiated mES cells. mRNA for the Na+/Ca2+ exchanger 1 isoform (NCX1) could be detected in undifferentiated mES cells and its expression levels seemed to gradually increase throughout the differentiation accompanied by increasing its Ca2+ extrusion function. At the middle stages of differentiation (after 10-day induction), more than 75% derived cardiomyocytes exhibited [Ca2+]i oscillations by blocking of Na+/K+ ATPase, suggesting the functional coupling with Na+/Ca2+ exchanger. From these results and RT-PCR analysis, we conclude that alpha2-subunit Na+/K+ ATPase mainly contributes to establish the functional coupling with NCX1 at the middle stages of differentiation of cardiomyocytes.

Functional expression of Ca2+ signaling pathways in mouse embryonic stem cells.

Mouse embryonic stem (mES) cells have the potential to differentiate into all types of cells, but the physiological properties of undifferentiated mES cells, including Ca2+ signaling systems, are not fully understood. In this study, we investigated Ca2+ signaling pathways in mES cells by using confocal Ca2+ imaging systems, patch clamp techniques and RT-PCR. The stimulations with ATP and histamine (His) induced a transient increase of intracellular Ca2+ concentration ([Ca2+]i), which were prevented by the pretreatment of 2-amino-ethoxydiphenyl borate (2-APB), a blocker for inositol-1,4,5-triphosphate receptors (InsP3Rs). The application of caffeine (Caff) or ryanodine (Ry) did not change [Ca2+]i. When stores were depleted with Ca2+ -ATPase blocker, thapsigargin (TG), or histamine, the capacitative Ca2+ entry (CCE) was observed. In whole cell patch clamp mode, store-operated Ca2+ currents could be recorded in cells treated with histamine and thapsigargin. On the other hand, voltage-operated Ca2+ channels (VOCCs) could not be elicited. The application of blockers for plasma membrane Ca2+ pump (PMCAs) (carboxeosin or caloxin2A1) induced a large increase of [Ca2+]i. When the Na+/Ca2+ exchangers (NCXs) were blocked by Na+ free solution or KBR7943, [Ca2+]i was also elevated. Using RT-PCR, mRNAs for InsP3Rs type-1, -2, and -3, PMCA-1 and -4, NCX-1, -2, and -3 could be detected. From these results, we conclude that Ca2+ release from ER is mediated by InsP3Rs in mES cells before differentiation and Ca2+ entry through plasma membrane is mainly mediated by the store-operated Ca2+ channels (SOCs). For the Ca2+ extrusion systems, both NCXs and PMCAs play important roles for maintaining the low level of [Ca2+]i.

The feasibility and clinical effects of dendritic cell-based immunotherapy targeting synthesized peptides for recurrent ovarian cancer.

BACKGROUND: Despite the increased rate of complete response to initial chemotherapy, most patients with advanced ovarian cancer relapse and succumb to progressive disease. Dendritic cell (DC)-based immunotherapy has been developed as a novel strategy for generating antitumor immunity as part of cancer treatments. The present study aimed to assess the feasibility and clinical effects of DC therapy for recurrent ovarian cancer (ROC). METHODS: This retrospective study included 56 ROC patients who initially received standard chemotherapy followed by DC-based immunotherapy targeting synthesized peptides at 2 institutions between March 2007 and August 2013. The adverse events (AEs) and clinical responses were examined. RESULTS: No serious treatment-related AEs were observed. Seventy one percent of the enrolled patients developed an immunologic response. The median survival time (MST) from ROC diagnosis was 30.4 months, and that from the first vaccination was 14.5 months. Albumin levels of ≥4.0 g/dL and lactate dehydrogenase levels of <200 IU/L before vaccination were identified as significant independent factors by multivariate Cox proportional hazard analysis. The MST from the first vaccination in patients with albumin levels of ≥4.0 and <4.0 g/dL were 19.9 and 11.6 months, respectively. The corresponding disease control rates were 36% and 15%, respectively. CONCLUSIONS: Our results demonstrated the feasibility and potential clinical effectiveness of DC-based immunotherapy for ROC patients. Additionally, a good nutritional status might be an important factor for further clinical effects.

Dendritic cell-based immunotherapy targeting synthesized peptides for advanced biliary tract cancer.

BACKGROUND: The aim of this retrospective study was to clarify the safety and efficacy of dendritic cell (DC)-based immunotherapy targeting synthesized peptides, Wilms tumor 1 (WT1) and Mucin 1, cell surface associated (MUC1) for biliary tract cancers (BTCs). METHODS: Sixty-five patients who had nonresectable, recurrent, or metastatic BTCs and received the DC-based immunotherapy were selected for the study. DCs were pulsed with WT1 and/or MUC1. The adverse events (AEs) and clinical responses were examined. RESULTS: No serious treatment-related AEs were observed. Median survival time (MST) from diagnosis and from the first vaccination was 18.5 and 7.2 months, respectively. By multivariate Cox proportional hazard analysis, the significant independent factors were found to be (1) combined chemotherapy, (2) albumin level ≥4.0 g/dL before vaccination, (3) C-reactive protein level <0.5 mg/dL before vaccination, and (4) fever after vaccination. The MST from the first vaccination with or without chemotherapy was 8.2 and 5.3 months, respectively (P = 0.016), and MST for the patients with prognostic nutritional index ≥40 and <40 was 8.1 and 5.0 months, respectively (P = 0.023). CONCLUSIONS: Although a small uncontrolled nonrandomized study, DC-based immunotherapy for BTCs was safe and produced a clinical response for the patients who underwent chemotherapy and maintained a good nutrition status.