P2560Metalloprotease nardilysin controls heart rate through the transcriptional regulation of ion channels critical for sinus automaticity

Acknowledgement/Funding

KAKENHI (17K09575)

4968Increased Gao expression underlies cardiac dysfunction and lethal arrhythmias accompanied with abnormal Ca2+ handling

Background

We previously demonstrated that a transcriptional repressor, neuron restrictive silencer factor (NRSF), maintains normal cardiac function and electrical stability. Transgenic mice expressing a dominant-negative mutant of NRSF in their hearts (dnNRSF-Tg) exhibit systolic dysfunction with cardiac dilation and premature death due to lethal arrhythmias like human dilated cardiomyopathy (DCM). Underlining mechanisms remain to be elucidated, however.

Purpose

We studied underling mechanisms by which NRSF maintains normal cardiac function to identify novel therapeutic targets for heart failure.

Methods and results

We generated cardiac-specific NRSF knockout mice (NRSFcKO) and confirmed that cardiac phenotypes of NRSFcKO are similar to those of dnNRSF-Tg.

cDNA microarray analysis revealed that cardiac gene expression of GNAO1 that encodes Gαo, a member of inhibitory G protein Gαi family, is increased in both dnNRSF-Tg and NRSFcKO ventricles.

We confirmed that GNAO1 is a direct target of NRSF through ChIP-seq analysis, reporter assay and electrophoretic mobility shift assay.

In dnNRSF-Tg, pharmacological inhibition of Gαo with pertussis toxin improved systolic dysfunction and knockdown of Gαo by crossing with GNAO1 knockout mice improved not only systolic function but also frequency of ventricular arrhythmias and survival rates.

Electrophysiological and biochemical analysis in ventricular myocytes obtained from dnNRSF-Tg demonstrated that genetic reduction of Gαo ameliorated abnormalities in Ca2+ handling, which include increased current density in surface sarcolemmal L-type Ca2+ channel, reduced content of sarcoplasmic reticulum Ca2+ and lowered peak of Ca2+ transient. Furthermore, genetic reduction of Gαo attenuated increased phosphorylation levels of CAMKII in dnNRSF-Tg ventricles, which presumably underlies the improvement in Ca2+ handling. In addition, we identified increased Gαo expression in ventricles of heart failure model mice induced by transverse aortic constriction and cardiac troponin T mutant DCM model mice, in both of which, genetic reduction of Gαo ameliorated cardiac dysfunction.

Figure 1

Conclusions

We found that increased expression of Gαo, induced by attenuation of NRSF-mediated repression, plays a crucial role in the progression of cardiac dysfunction and lethal arrhythmias by evoking Ca2+ handling abnormality. These data demonstrate that Gαo is a potential therapeutic target for heart failure.

P3846The association between statin prescription, recurrent venous thromboembolism and bleeding events: from the COMMAND VTE Registry

Background

Statin prevents occurrence and recurrence of atherosclerotic events. With regard to venous thromboembolism (VTE), a randomized controlled trial suggested that statin reduced occurrence of VTE, whereas its usefulness as secondary prevention of VTE remains to be elucidated.

Purpose

This study aimed to assess the association between statin prescription, recurrent VTE and bleeding events in patients with VTE.

Methods

The COMMAND VTE Registry is a multicentre registry enrolling consecutive 3027 patients with acute symptomatic VTE among 29 centres in Japan. We divided the cohort into the patients who were prescribed statin (N=437) and those not (N=2590), and compared the two groups. We assessed hazard ratios (HRs) of those with statin relative to those without for long-term clinical outcomes (recurrent symptomatic VTE and International Society of Thrombosis and Hemostasis [ISTH] major bleeding). Because the durations of anticoagulation therapy were widely different between the two groups, we constructed Cox's proportional hazard model incorporating status of anticoagulation during the follow-up period as a time-varying covariate. Also, because the incidences of death were strikingly different between the two groups due to the difference in the prevalence of active cancer, we used Fine-Gray's subdistribution hazard model in the presence of competing risks. We incorporated clinically relevant factors into these two models as covariates (10 factors for recurrent VTE and 11 for major bleeding).

Results

The statin group was significantly older than the non-statin group (statin 71.2±11.8 vs. non-statin 66.5±15.8, P<0.001). The prevalence of active cancer in the statin group was less than one-half of that in the non-statin group (12% vs. 25%, P<0.001), and the cumulative 3-year incidence of death was significantly lower in the statin group than in the non-statin group (12.8% vs. 26.1%, log-rank P<0.001). The table shows the adjusted HRs of the statin group relative to the non-statin group. The HRs of the statin group relative to non-statin group for recurrent VTE were significantly low, but those for major bleeding were insignificant.

Adjusted hazard ratios Outcome measures Model 1 P value Model 2 P value Adjusted HR [95% CI] Adjusted HR [95% CI] Recurrent VTE 0.59 [0.36–0.98] 0.042 0.53 [0.32–0.89] 0.02 Major bleeding 0.87 [0.60–1.24] 0.43 0.997 [0.69–1.43] 0.99 Model 1 derived from Cox's model with time-varying covariate of anticoagulation status. Model 2 derived from Fine-Gray's model.

Study flowchart

Conclusions

Prescription of satin was associated with significantly low risks for recurrent VTE, whereas that was not for major bleeding events. Statin could be a potential treatment option for secondary prevention of VTE.

P1029Catheter ablation outcome and heart failure hospitalization in atrial fibrillation patients: insights from the Kansai plus atrial fibrillation (KPAF) registry

Background

Heart failure (HF) is the leading cause of death in patients with atrial fibrillation (AF). Radiofrequency catheter ablation (RFCA) for AF is effective to maintain sinus rhythm.

Purpose

We sought to clarify whether AF ablation outcome influenced incidence of HF hospitalization after the procedures.

Methods

We conducted a large-scale, prospective, multicenter, observational study. A total of 5010 consecutive patients who underwent an initial RFCA for AF in 26 centers were enrolled (average age, 64±10 years; non-paroxysmal AF, 35.6%). The median follow-up duration was 2.9 years.

Results

The 3-year cumulative incidence of AF recurrence after a single procedure was 40.2%. The 3-year incidence of hospitalization for HF was observed in 92 patients (1.8%) and was significantly higher in patients with AF recurrence than those without it (3.3% vs 0.84%, log-rank p<0.001). After adjustment by advanced age,(≥65 years), reduced left ventricular ejection fraction (≤50%), low estimated glomerular filtration rate (≤60ml/min), and history of HF, all of which were statistically associated with a risk of HF hospitalization (p<0.1, respectively), AF recurrence after the index RFCA was an independent predictor of HF hospitalization (hazard ratio [HR]; 3.17, 95% confidence interval [CI]; 2.06–5.04, p<0.001).Even after multiple procedures (1425 re-ablation sessions in 1274 patients [25.4%]), AF recurrence after the last procedure was an independent predictor of HF hospitalization (HR; 2.83, 95% CI; 1.89–4.24, p<0.001).

Conclusions

Among AF patients receiving RFCA, those with AF recurrence were at greater risk of heart failure hospitalization than were patients without AF recurrence. These differences should be noted when treating AF patients in actual clinical practice.

Acknowledgement/Funding

This study was supported by the Research Institute for Production Development in Kyoto, Japan.

P5650Improvement in ejection fraction predicts heart failure after catheter ablation for atrial fibrillation in patients with left ventricular systolic dysfunction: from the KPAF registry

Introduction

The presence of atrial fibrillation (AF) in patients with reduced left ventricular ejection fraction (LVEF) is associated with increased risks of mortality and hospitalization for heart failure (HF). Although prior studies reported that catheter ablation (CA) for AF in low LVEF patients reduced risks of all-cause mortality and HF hospitalization, the predictors of worsening HF after ablation has not been adequately evaluated.

Purpose

The purpose of this study was to investigate the impact of improvement in LVEF after AF ablation on the incidence of subsequent HF hospitalization in patients with low LVEF.

Methods

The Kansai Plus Atrial Fibrillation (KPAF) Registry is a multicenter registry enrolling 5,013 consecutive patients undergoing first-time ablation for AF. The current study population consisted of 1,031 patients with reduced LVEF of <60%. We divided the study population into 3 groups according to LVEF at follow-up; 678 patients (65.8%) with improved LVEF (≥5 U change in LVEF), 288 patients (27.9%) with unchanged LVEF (−5 U ≤ change in LVEF <5 U) and 65 patients (6.3%) with worsened LVEF (<−5 U change in LVEF).

Results

During the median follow-up of 1067 [879–1226] days, patients improved LVEF had lower rate of HF hospitalization, compared with those with unchanged and worsened LVEF (2.1%, 8.0%, and 21.5%, respectively, P<0.0001). Recurrent atrial tachyarrhythmias were documented in 43.5%, 47.2% and 67.7%, respectively (P=0.0008).

Figure 1

Conclusion

Among patients with reduced LVEF undergoing AF ablation, patients with subsequently improved LVEF in association with maintained sinus rhythm had markedly lower risk of HF hospitalization during follow-up as compared with those with unchanged or worsened LVEF.

EFFECT ON MICROBIAL PRODUCTS ON CAESIUM ELUTION BEHAVIOUR FROM CLAY MINERALS

Some microorganisms in the environment make siderophores, which are low molecular chelators, to take up minerals from soil. Eleven bacteria were separated from the root of white clover by chlome azrol S (CAS) assay. Each bacterium was incubated in casamino acid (CAA) culture, and siderophores in CAA culture were purified. These extractions were applied to biotite or vermiculite spiked with Cs. From each clay mineral, 57.1-72.8% (5100 ppm), 55.6-63.8% (920 ppm) and 48.6-54.3% (2300 ppm), 31.6-34.4% (520 ppm) was eluted, respectively. To understand elution behaviour, Cs desorption ratio of each clay was measured every 30 min. The results indicate Cs elution was occurred quickly.

P5592Thrombolysis with tissue plasminogen activator for patients with acute pulmonary embolisms in the real world: from the COMMAND VTE Registry

Background/Introduction

There is still uncertainty about the optimal usage of thrombolysis for acute pulmonary embolisms (PEs), leading to widely varying usage of thrombolysis in the real world. However, these have not been fully evaluated yet.

Purpose

We sought to evaluate the management strategies and clinical outcomes of thrombolysis for acute PEs in the real world.

Methods

The COMMAND VTE Registry is a multicenter registry enrolling 3,027 consecutive patients with acute symptomatic venous thromboembolisms in Japan between January 2010 and August 2014. The present study population consisted of 1,549 patients with PEs who received tissue plasminogen activator (t-PA) thrombolysis (N=180, 12%), or those who did not (N=1,369). The effectiveness outcome was all-cause death. The safety outcome was major bleeding. We used a multivariable logistic regression analysis to estimate the odds ratio (OR) and 95% confidence intervals (CI), to adjust clinically relevant confounders (age, sex, history of major bleeding, active cancer, and anemia). Additionally, we conducted stratified analysis by clinical severity, and we also evaluated clinical outcomes according to dosages of t-PA.

Results

Patients with t-PA thrombolysis were younger, and more frequently had higher body weight, but less frequently had active cancer, history of major bleeding, and anemia. More than half of patients with t-PA thrombolysis were patients with mild PEs, and the proportions of t-PA thrombolysis varied widely across the participating centers. More than half of patients received low-dose of t-PA (<20,000 IU/kg). As for the effectiveness, 9 (5.0%) patients in the t-PA thrombolysis group and 95 (6.9%) patients in the non t-PA thrombolysis group died at 30 days (Crude OR, 0.71; 95% CI 0.35–1.42, P=0.33). As for the safety, 7 (3.9%) patients in the t-PA thrombolysis group and 22 (1.6%) patients in the non t-PA thrombolysis group experienced major bleeding events at 10 days (Crude OR, 2.48; 95% CI 1.04–5.88, P=0.04). T-PA thrombolysis group had a significantly higher risk for 10-day major bleeding (Adjusted OR, 4.01; 95% CI 1.57–10.2, P=0.004), but not a lower risk for 30-day mortality (Adjusted OR, 1.10; 95% CI 0.53–2.28, P=0.79), although the risk for 30-day mortality was significantly lower in those with severe PEs (Adjusted OR, 0.36; 95% CI 0.15–0.88, P=0.02). After adjusting confounders, the 10-day major bleeding risk of the low-dose of t-PA group relative to the standard-dose of t-PA group tended to be lower (Adjusted OR, 0.07; 95% CI 0.004–1.05, P=0.05).

Conclusions

In the present real-world registry, relatively large number of patients received t-PA thrombolysis with wide variation across the participating centers. T-PA thrombolysis was significantly associated with a higher risk for major bleeding, but not a lower risk for mortality, although there appeared to be a benefit of t-PA thrombolysis in decreasing the risk for mortality in patients with severe PEs.

Acknowledgement/Funding

Research Institute for Production Development, Mitsubishi Tanabe Pharma Corporation

P6461The long-term clinical comparisons of symptomatic patients of pulmonary embolism with and those without deep vein thrombosis: from the COMMAND VTE Registry

Background

Venous thromboembolism (VTE), including pulmonary embolism (PE) and deep vein thrombosis (DVT), has significant morbidity and mortality. Acute PE, in particular, is fatal if we miss it, and symptomatic patients of PE sometimes have concomitant DVT.

Purpose

This study compared the risk of mortality in symptomatic patients of PE with and those without DVT in the long term.

Methods

The COMMAND VTE Registry is a multicenter registry enrolling consecutive 3027 patients with acute symptomatic VTE objectively confirmed by imaging examination or by autopsy among 29 centers in Japan between January 2010 and August 2014. Patients with both PE and DVT (N=1334) were regarded as PE patients, and the current study population consisted of 1715 PE patients and 1312 DVT patients.

Results

There were 1203 symptomatic patients of PE, including 381 without and 822 with DVT. In our cohort, the mean age was 67.9±14.9 years, 63% was female, 44% had hypertension, 12% diabetes mellitus, 5% history of VTE. There were 20% of active cancer. Baseline characteristics were well matched except for dyslipidemia (18% vs. 23%, p=0.021) and atrial fibrillation (8% vs. 5%, p=0.045). Patients without DVT had a more severe clinical presentation compared to those with DVT, including hypoxemia, shock and arrest. Moreover, Initial parenteral anticoagulation therapy in the acute phase was administered less frequently in patients without DVT (89% vs. 96%, P=0.0001). Two groups received thrombolysis (20% vs. 26%, P=0.18) and mechanical supports (Ventilator 14% vs. 5%, p<0.001, PCPS 5% vs. 3%, p<0.001, respectively). During follow-up, 93 (8%) patients experienced recurrent VTE events and 98 (8%) major bleeding events, and 323 (27%) patients died. The most frequent cause of death was cancer (11%). There were a significant differences in the cumulative incidences of all-cause death between the groups (32% vs. 24%, P=0.006), whereas there was significant difference in VTE-related death (13% vs. 4%, p<0.001). Estimated freedom rates from death for patients of PE without and those with DVT were as follows: 88% vs 99% at 10-day, 86% vs 95% at 1-month, 75% vs 83% at 1-year, and 64% vs 71% at 5-year, respectively.

Landmark analysis

Conclusions

In symptomatic patients of PE, there was a difference in mortality between groups, but no difference in recurrent VTE. Patients without DVT had a more severe clinical presentation compared to those with DVT, and many VTE-related deaths in the acute phase. The one-month mortality rate differed statistically between groups, but there was no significant difference in long-term survival beyond one month. Most of deaths were due to underlying diseases, mainly cancer, and less commonly due to VTE in the long term.

Acknowledgement/Funding

Research Institute for Production Development, Mitsubishi Tanabe Pharma Corporation

P2770Clinical characteristics and outcomes of venous thromboembolism according to patients with versus without atrial fibrillation: from the COMMAND VTE Registry

Background/Introduction

Oral anticoagulants are widely used for the treatment and second prevention of venous thromboembolism (VTE) and stroke prevention in atrial fibrillation (AF). VTE and AF are common diseases and these sometimes might coexist. However, there are few reports about the relationship between VTE and AF.

Purpose

We sought to evaluate the clinical characteristics and outcomes in VTE patients with AF.

Methods

The COMMAND VTE Registry is a multicenter registry enrolling consecutive 3027 patients with acute symptomatic VTE objectively confirmed by imaging examination or by autopsy among 29 centers in Japan between January 2010 and August 2014. The current study population consisted of 129 patients with AF (AF group) and 2898 patients without AF (non-AF group). We compared the clinical characteristics, management strategies and long-term outcomes between the 2 groups.

Results

The AF group was older (mean age: 75.3 vs. 66.8 years, P<0.001), and more often had co-morbidities such as hypertension (54.3% vs. 37.7%, P<0.001), diabetes mellitus (20.2% vs. 12.4%, P=0.01), chronic kidney disease (28.7% vs. 18.5%, P=0.004), heart failure (28.7% vs. 18.5%, P=0.004), history of stroke (20.2% vs. 8.4%, P<0.001), and history of major bleeding (12.4% vs. 7.4%, P=0.04) compared with the non-AF group, whereas there were no significant differences in the proportions of active cancer at diagnosis (18.6% vs. 23.2%, P=0.23) and pulmonary embolism at presentation (64.3% vs. 56.3%, P=0.07). The proportion of anticoagulation therapy beyond acute phase was not significantly different (94% vs. 93%, P=0.60), while the cumulative discontinuation rates of anticoagulation therapy was significantly lower in the AF group (26.9% vs. 43.4% at 3 years, Log-rank P=0.03). The cumulative 5-year incidences of recurrent VTE and major bleeding were not significantly different (Recurrent VTE: 7.6% vs. 10.6%, Log-rank P=0.89; Major bleeding: 18.6% vs. 11.8%, Log-rank P=0.07). After adjusting for potential confounders, the risks of the AF group relative to the non-AF group for recurrent VTE and major bleeding remained insignificant (HR 1.19, 95% CI 0.54–2.28, P=0.64; HR 1.28, 95% CI 0.73–2.06, P=0.37). The cumulative 5-year incidence of all-cause death was significantly higher in the AF-group (49.1% vs. 28.6%, Log-rank P<0.001). After adjusting for potential confounders, the risks of the AF group relative to the non-AF group for all-cause death remained significant (HR 1.63, 95% CI 1.23–2.15, P<0.001). The proportion of deaths due to cancer was lower in the AF group (30% vs. 55%, P<0.001), while the proportion of cardiac deaths was higher in the AF group (16.1% vs. 4.0%, P<0.001).

The outcomes of VTE patients with AF

Conclusions

The risks for recurrent VTE between patients with AF and those without AF were not significantly different, although patients with AF received longer-term anticoagulation therapy, whereas the risks for major bleeding tended to be higher in patients with AF.

Acknowledgement/Funding

Research Institute for Production Development, Mitsubishi Tanabe Pharma Corporation

Association between maternal alcohol consumption during pregnancy and risk of preterm delivery: the Japan Environment and Children's Study

OBJECTIVE

To examine the association between maternal alcohol consumption during pregnancy and the risk of preterm delivery.

DESIGN

Prospective cohort study.

SETTING

The Japan Environment and Children's Study (JECS).

POPULATION

A total of 94 349 singleton pregnancies.

METHODS

Participants completed questionnaires detailing alcohol consumption during the first trimester and during the second and third trimesters. Participants were divided into four categories according to alcohol consumption (non-drinkers, consumers of 1-149 g, 150-299 g and ≥300 g ethanol/week). We examined the effect of alcohol consumption during different stages of pregnancy on the risk of preterm delivery. Odds ratios (OR) and 95% CI were calculated relative to non-drinkers using logistic regression.

MAIN OUTCOME MEASURES

Medical record-based preterm delivery.

RESULTS

Alcohol consumption during the second and third trimesters, but not during the first trimester, was associated with increased risk of preterm delivery. Heavy alcohol consumption (≥300 g ethanol/week) during the second and third trimesters was associated with a four-fold higher risk compared with non-drinkers (multivariable OR 4.52; 95% CI 1.68-12.2). Light alcohol consumption (1-149 g ethanol/week) tended to be associated with lower risk of preterm delivery (multivariable OR 0.78; 95% CI 0.60-1.00).

CONCLUSIONS

Heavy alcohol consumption during the second and third trimesters was associated with increased risk of preterm delivery among pregnant women.

TWEETABLE ABSTRACT

Heavy drinking during pregnancy may increase the risk of preterm delivery.

Ral GTPase Activation by Downregulation of RalGAP Enhances Oral Squamous Cell Carcinoma Progression

Ral small GTPases, consisting of RalA and RalB, are members of the Ras family. Their activity is upregulated by RalGEFs. Since several RalGEFs are downstream effectors of Ras, Ral is activated by the oncogenic mutant Ras. Ral is negatively regulated by RalGAP complexes that consist of a catalytic α1 or α2 subunit and its common partner β subunit and similarly regulate the activity of RalA as well as RalB in vitro. Ral plays an important role in the formation and progression of pancreatic and lung cancers. However, the involvement of Ral in oral squamous cell carcinoma (OSCC) is unclear. In this study, we investigated OSCC by focusing on Ral. OSCC cell lines with high Ral activation exhibited higher motility. We showed that knockdown of RalGAPβ increased the activation level of RalA and promoted the migration and invasion of HSC-2 OSCC cells in vitro. In contrast, overexpression of wild-type RalGAPα2 in TSU OSCC cells attenuated the activation level of RalA and inhibited cell migration and invasion. Real-time quantitative polymerase chain reaction analysis of samples from patients with OSCC showed that RalGAPα2 was downregulated in oral cancer tissues as compared with normal epithelia. Among patients with OSCC, those with a lower expression of RalGAPα2 showed a worse overall survival rate. A comparison of DNA methylation and histone modifications of the RalGAPα2 gene in OSCC cell lines suggested that crosstalk among DNA methylation, histone H4Ac, and H3K27me2 was involved in the downregulation of RalGAPα2. Thus, activation of Ral GTPase by downregulation of RalGAP expression via a potential epigenetic mechanism may enhance OSCC progression.

A Polymorphism rs6726395 in Nrf2 Contributes to the Development of Emphysema-Associated Age in Smokers Without COPD

INTRODUCTION

Several studies have reported that single nucleotide polymorphisms (SNPs) in the gene encoding NF-E2-related factor 2 (Nrf2) contribute to airflow limitations in smokers without COPD. Although small airway lesions and emphysema contribute cooperatively to airflow limitation, the relationship between Nrf2 SNPs and the development of emphysema in smokers without COPD is not well understood.

METHODS

Healthy subjects who underwent an annual health checkup with computed tomography (CT) of the chest at Osaka City University Hospital were prospectively recruited. The percentage of low-attenuation area (%LAA) on chest CT was quantified, and correlations between %LAA, Nrf2 SNP [rs6726395 (G/A)] genotypes, and clinical characteristics were examined.

RESULTS

A total of 245 subjects without COPD [non-/light-smoker: 153 (62.4%) and smoker: 92 (37.6%)] were enrolled. The %LAA in the upper lung field was higher than that in the lower lung field (p < 0.001). The %LAA in smokers was significantly higher than that in non-/light-smokers (p = 0.021). The %LAA showed significant but weak correlation with age in all subjects (r = 0.141, p = 0.028). Divided by genotype, the %LAA of the upper lung field was significantly correlated with age in smokers with genotype GG (wild type) (r = 0.333, p = 0.022), but was not significantly correlated with age in smokers with genotype AG/AA. These correlations were not observed in non-/light smokers.

CONCLUSION

A polymorphism rs6726395 in Nrf2 can contribute to the development of emphysema-associated aging in smokers. The Nrf2 SNP may be a predictive factor for smoking-induced emphysema, and genotyping of Nrf2 SNP may serve as biomarker for emphysema prevention.

Induced expression of GINS complex is an essential step for reactivation of quiescent stem-like tumor cells within the peri-necrotic niche in human glioblastoma

PURPOSE

Glioblastoma is still intractable despite the progress in therapies, and the intractability is attributable to a minor population of stem-like tumor cells. As a niche harboring quiescent stem-like tumor cells with potentially high tumorigenicity, we have specified an area around large ischemic necrosis, termed 'peri-necrotic niche', in glioblastoma. In this study, the behavior of tumor cells inside and outside the peri-necrotic niche was analyzed to find out molecules responsible for reactivation of quiescent stem-like tumor cells to proliferate outside the niche.

METHODS

Expression of Ki-67 and GINS complex composed of SLD5, PSF1, PSF2 and PSF3 was analyzed by immunohistochemistry in human glioblastoma tissue samples. Proliferation assays, immunoblotting and siRNA experiments were performed using a glioblastoma cell line.

RESULTS

Immunohistochemical analysis revealed quiescent and proliferative phenotypes of tumor cells inside and outside the niche, respectively, and the proliferation was spatially correlated with the expression of GINS components in tumor cells. To mimic the tissue microenvironment inside versus outside the niche, glioblastoma cells were cultured under hypoxic versus normoxic conditions, or without versus with serum. Quiescence and proliferation of tumor cells were reversibly determined by the microenvironment inside and outside the niche, respectively, and proliferative activities paralleled the expression levels of GINS components. Furthermore, the reactivation of proliferation after reoxygenation or serum replenishment was suppressed in quiescent tumor cells with PSF1 knockdown.

CONCLUSIONS

These findings indicate the essential role of GINS complex in the switch between quiescence and proliferation of tumor cells inside and outside the peri-necrotic niche.

X-ray diffraction study on the orientation dynamics of biaxial microcrystals under static and rotating magnetic fields

The orientation of microcrystals of DyBa₂Cu₃O_y (y ~ 7) under static and rotating magnetic fields was studied.

Proposal of patient-specific growth plate cartilage xenograft model for FGFR3 chondrodysplasia

OBJECTIVE

FGFR3 chondrodysplasia is caused by a gain-of-function mutation of the FGFR3 gene. The disease causes abnormal growth plate cartilage and lacks effective drug treatment. We sought to establish an in vivo model for the study of FGFR3 chondrodysplasia pathology and drug testing.

DESIGN

We created cartilage from human induced pluripotent stem cells (hiPSCs) and transplanted the cartilage into the subcutaneous spaces of immunodeficient mice. We then created cartilage from the hiPSCs of patients with FGFR3 chondrodysplasia and transplanted them into immunodeficient mice. We treated some mice with a FGFR inhibitor after the transplantation.

RESULTS

Xenografting the hiPSC-derived cartilage reproduced human growth plate cartilage consisting of zones of resting, proliferating, prehypertrophic and hypertrophic chondrocytes and bone in immunodeficient mice. Immunohistochemistry of xenografts using anti-human nuclear antigen antibody indicated that all chondrocytes in growth plate cartilage were human, whereas bone was composed of human and mouse cells. The pathology of small hypertrophic chondrocytes due to up-regulated FGFR3 signaling in FGFR3 skeletal dysplasia was recapitulated in growth plate cartilage formed in the xenografts of patient-specific hiPSC-derived cartilage. The mean diameters of hypertrophic chondrocytes between wild type and thanatophoric dysplasia were significantly different (95% CI: 13.2-26.9; n = 4 mice, one-way analysis of variance (ANOVA)). The pathology was corrected by systemic administration of a FGFR inhibitor to the mice.

CONCLUSION

The patient-specific growth plate cartilage xenograft model for FGFR3 skeletal dysplasia indicated recapitulation of pathology and effectiveness of a FGFR inhibitor for treatment and warrants more study for its usefulness to study disease pathology and drug testing.