Ascorbic acid induces MLC2v protein expression and promotes ventricular-like cardiomyocyte subtype in human induced pluripotent stem cells derived cardiomyocytes.

Introduction: The potentially unlimited number of cardiomyocyte (CMs) derived from human induced pluripotent stem cells (hiPSCs) in vitro facilitates high throughput applications like cell transplantation for myocardial repair, disease modelling, and cardiotoxicity testing during drug development. Despite promising progress in these areas, a major disadvantage that limits the use of hiPSC derived CMs (hiPSC-CMs) is their immaturity. Methods: Three hiPSC lines (PCBC-hiPSC, DP3-hiPSCs, and MLC2v-mEGFP hiPSC) were differentiated into CMs (PCBC-CMs, DP3-CMs, and MLC2v-CMs, respectively) with or without retinoic acid (RA). hiPSC-CMs were either maintained up to day 30 of contraction (D30C), or D60C, or purified using lactate acid and used for experiments. Purified hiPSC-CMs were cultured in basal maturation medium (BMM) or BMM supplemented with ascorbic acid (AA) for 14 days. The AA treated and non-treated hiPSC-CMs were characterized for sarcomeric proteins (MLC2v, TNNI3, and MYH7), ion channel proteins (Kir2.1, Nav1.5, Cav1.2, SERCA2a, and RyR), mitochondrial membrane potential, metabolomics, and action potential. Bobcat339, a selective and potent inhibitor of DNA demethylation, was used to determine whether AA promoted hiPSC-CM maturation through modulating DNA demethylation. Results: AA significantly increased MLC2v expression in PCBC-CMs, DP3-CMs, MLC2v-CMs, and RA induced atrial-like PCBC-CMs. AA treatment significantly increased mitochondrial mass, membrane potential, and amino acid and fatty acid metabolism in PCBC-CMs. Patch clamp studies showed that AA treatment induced PCBC-CMs and DP3-CMs adaptation to a ventricular-like phenotype. Bobcat339 inhibited MLC2v protein expression in AA treated PCBC-CMs and DP3-CMs. DNA demethylation inhibition was also associated with reduced TET1 and TET2 protein expressions and reduced accumulation of the oxidative product, 5 hmC, in both PCBC-CMs and DP3-CMs, in the presence of AA. Conclusions: Ascorbic acid induced MLC2v protein expression and promoted ventricular-like CM subtype in hiPSC-CMs. The effect of AA on hiPSC-CM was attenuated with inhibition of TET1/TET2 mediated DNA demethylation.

Macrophage, a potential targeted therapeutic immune cell for cardiomyopathy.

Cardiomyopathy is a major cause of heart failure, leading to systolic and diastolic dysfunction and promoting adverse cardiac remodeling. Macrophages, as key immune cells of the heart, play a crucial role in inflammation and fibrosis. Moreover, exogenous and cardiac resident macrophages are functionally and phenotypically different during cardiac injury. Although experimental evidence has shown that macrophage-targeted therapy is promising in cardiomyopathy, clinical translation remains challenging. In this article, the molecular mechanism of macrophages in cardiomyopathy has been discussed in detail based on existing literature. The issues and considerations of clinical treatment strategies for myocardial fibrosis has also been analyzed.

A diastolic dysfunction model in non-human primates with transverse aortic constriction.

Transverse aortic constriction (TAC) has been widely used to study cardiac hypertrophy, fibrosis, diastolic dysfunction, and heart failure in rodents. Few studies have been reported in preclinical animal models. The similar physiology and anatomy between non-human primates (NHPs) and humans make NHPs valuable models for disease modeling and testing of drugs and devices. In the current study, we aimed to establish a TAC model in NHPs and characterize the structural and functional profiles of the heart after TAC. A non-absorbable suture was placed around the aorta between the brachiocephalic artery and left common carotid artery to create TAC. NHPs were divided into 2 groups according to pressure gradient (PG): the Mild Group (PG=31.01 ± 12.40 mmHg, n=3) and the Moderate Group (PG=53.00 ± 9.37 mmHg, n=4). At 4 weeks after TAC, animals in both TAC groups developed cardiac hypertrophy: enlarged myocytes and increased wall thickness of the left ventricular (LV) anterior wall. Although both TAC groups had normal systolic function that was similar to a Sham Group, the Moderate Group showed diastolic dysfunction that was associated with more severe cardiac fibrosis, as evidenced by a reduced A wave velocity, large E wave velocity/A wave velocity ratio, and short isovolumic relaxation time corrected by heart rate. Furthermore, no LV arrhythmia was observed in either animal group after TAC. A diastolic dysfunction model with cardiac hypertrophy and fibrosis was successfully developed in NHPs.

I-κB Kinase-ε Deficiency Attenuates the Development of Angiotensin II-Induced Myocardial Hypertrophy in Mice.

I-κB kinase-ε (IKKε) is a member of the IKK complex and a proinflammatory regulator that is active in many diseases. Angiotensin II (Ang II) is a vasoconstricting peptide hormone, and Ang II-induced myocardial hypertrophy is a common cardiovascular disease that can result in heart failure. In this study, we sought to determine the role of IKKε in the development of Ang II-induced myocardial hypertrophy in mice. Wild-type (WT) and IKKε-knockout (IKKε-KO) mice were generated and infused with saline or Ang II for 8 weeks. We found that WT mouse hearts have increased IKKε expression after 8 weeks of Ang II infusion. Our results further indicated that IKKε-KO mice have attenuated myocardial hypertrophy and alleviated heart failure compared with WT mice. Additionally, Ang II-induced expression of proinflammatory and collagen factors was much lower in the IKKε-KO mice than in the WT mice. Apoptosis and pyroptosis were also ameliorated in IKKε-KO mice. Mechanistically, IKKε bound to extracellular signal-regulated kinase (ERK) and the mitogen-activated protein kinase p38, resulting in MAPK/ERK kinase (MEK) phosphorylation, and IKKε deficiency inhibited the phosphorylation of MEK-ERK1/2 and p38 in mouse heart tissues after 8 weeks of Ang II infusion. The findings of our study reveal that IKKε plays an important role in the development of Ang II-induced myocardial hypertrophy and may represent a potential therapeutic target for the management of myocardial hypertrophy.

Angiopoietin-1 enhanced myocyte mitosis, engraftment, and the reparability of hiPSC-CMs for treatment of myocardial infarction.

AIMS: To examine whether transient over-expression of angiopoietin-1 (Ang-1) increases the potency of hiPSC-CMs for treatment of heart failure. METHODS AND RESULTS: Atrial hiPSC-CMs (hiPSC-aCMs) were differentiated from hiPSCs and purified by lactic acid and were transfected with Ang-1 (Ang-1-hiPSC-aCMs) plasmid using lipoSTEM. Ang-1 gene transfection efficiency was characterized in vitro. Gene transfected CMs (1×106) were seeded into a fibrin/thrombin patch and implanted on the rat-infarcted left ventricular (LV) anterior wall after myocardial infarction (MI). Echo function was determined at 1- and 6 weeks post-MI. Immunohistochemistry study was performed at 6 weeks post-MI. Ang-1 (20 and 40 ng/mL) protected hiPSC-aCMs from hypoxia through up-regulating pERK1/2 and inhibiting Bax protein expressions. Ang-1-hiPSC-aCMs transiently secreted Ang-1 protein up to 14 days, with peak level on day-2 post-transfection (24.39 ± 13.02 ng/mL) in vitro. Animal study showed that transplantation of Ang-1-hiPSC-aCM seeded patch more effectively limited rat heart apoptosis at 1 day post-MI as compared with LipoSTEM-Ang-1 or hiPSC-aCMs transplantation. Ang-1-hiPSC-aCMs transplantation induced host (rat) and donor (human) CM mitosis and arteriole formation, improved cell engraftment rate, more effectively limited LV dilation (EDV = 460.7 ± 96.1 µL and ESV = 219.8 ± 72.9 µL) and improved LV global pump function (EF = 53.1 ± 9%) as compared with the MI (EDV = 570.9 ± 91.8 µL, P = 0.033; ESV = 331.6 ± 71.2 µL, P = 0.011; EF = 42.3 ± 4.1%, P = 0.02) or the LipoSTEM-Ang-1 injected (EDV = 491.4 ± 100.4 µL, P = 0.854; ESV = 280.9 ± 71.5 µL, P = 0.287; EF = 43.2 ± 4.6, P = 0.039) or hiPSC-CM transplanted (EDV = 547.9 ± 55.5 µL, P = 0.095; ESV = 300.2 ± 88.4 µL, P = 0.075; EF = 46 ± 10.9%, P = 0.166) animal groups at 6 weeks post-MI and treatment. CONCLUSION: Transient over-expression of Ang-1 enhanced hiPSC-aCM mitosis and engraftment and increased the reparability potency of hiPSC-aCMs for treatment of MI.

A Novel Molecular Mechanism of IKKε-Mediated Akt/mTOR Inhibition in the Cardiomyocyte Autophagy after Myocardial Infarction.

Autophagy of cardiomyocytes after myocardial infarction (MI) is an important factor affecting the prognosis of MI. Excessive autophagy can lead to massive death of cardiomyocytes, which will seriously affect cardiac function. IKKε plays a crucial role in the occurrence of autophagy, but the functional role in MI remains largely unknown. To evaluate the impact of IKKε on the autophagy of cardiomyocytes after MI, MI was induced by surgical left anterior descending coronary artery ligation in IKKε knockout (KO) mice and wild-type (WT) mice. Starvation of H9c2 cells with IKKε siRNA and rescued with IKKε overexpressed afterwards to test the mechanism of IKKε in autophagy in vitro. Our results demonstrated that the expression of IKKε was upregulated in mice myocardial tissues which were consistent with cardiomyocyte autophagy after MI. Significantly, the IKKε KO mice showed increased infarct size, decreased viable cardiomyocytes, and exacerbated cardiac dysfunction when compared with the wild-type mice. Western blot and electron micrography analysis also revealed that loss of IKKε induces excessive cardiomyocyte autophagy and reduced the expression of p-Akt and p-mTOR. Similar results were observed in IKKε siRNA H9c2 cells in vitro which were under starvation injury. Notably, the levels of p-Akt and p-mTOR can restore in IKKε rescued cells. In conclusion, our results indicated that IKKε protects cardiomyocyte survival by reduced autophagy following MI via regulation of the Akt/mTOR signaling pathway. Thus, our study suggests that IKKε might represent a potential therapeutic target for the treatment of MI.

Dexamethasone inhibits regeneration and causes ventricular aneurysm in the neonatal porcine heart after myocardial infarction.

AIMS: Recently, we demonstrated that the hearts of neonatal pigs (2-day old) have regenerative capacity, likely driven by cardiac myocyte division, but this potential is lost immediately after postnatal day 3. However, it is unknown if corticosteroid, a broad anti-inflammatory agent, will abrogate the regenerative capacity in the hearts of neonatal pigs. The aim of the current study is to evaluate the effect Dexamethasone (Dex), a broad anti-inflammatory agent, on heart regeneration, structure, and function of the neonatal pigs' post-myocardial infarction (MI). METHODS AND RESULTS: Dex (0.2 mg/kg/day) was injected intramuscularly into the neonatal pig (age: 2 days postnatal) during the first week post-MI. Myocardial scar and left ventricular function were determined by cardiac magnetic resonance (CMR) imaging. Bromodeoxyuridine (BrdU) pulse-chase labeling, histology, immunohistochemistry, and flow cytometry were performed to determine inflammatory cell infiltration, CM cytokinesis, and myocardial fibrosis. Dex injection during the first-week suppressed acute inflammation post-MI in the pig hearts. It inhibited BrdU incorporation to pig CMs and CM cytokinesis via inhibiting aurora-B protein expression which was associated with mature scar formation and thinned walls at the infarct site. CMR imaging showed Dex caused left ventricular aneurysm and poor ejection fraction. CONCLUSIONS: Dex inhibited CM cytokinesis and functional recovery and caused ventricular aneurysm in the hearts of 2-day old pigs post-MI.

IKK Epsilon Deficiency Attenuates Angiotensin II-Induced Abdominal Aortic Aneurysm Formation in Mice by Inhibiting Inflammation, Oxidative Stress, and Apoptosis.

Abdominal aortic aneurysm (AAA) is a vascular disorder that is considered a chronic inflammatory disease. However, the precise molecular mechanisms involved in AAA have not been fully elucidated. Recently, significant progress has been made in understanding the function and mechanism of action of inhibitor of kappa B kinase epsilon (IKKε) in inflammatory and metabolic diseases. The angiotensin II- (Ang II-) induced or pharmacological inhibitors were established to test the effects of IKKε on AAA in vivo. After mice were continuously stimulated with Ang II for 28 days, morphologically, we found that knockout of IKKε reduced AAA formation and drastically reduced maximal diameter and severity. We also observed a decrease in elastin degradation and medial destruction, which were independent of systolic blood pressure or plasma cholesterol concentrations. Western blot analyses and immunohistochemical staining were carried out to measure IKKε expression in AAA tissues and cell lines. AAA phenotype of mice was measured by ultrasound and biochemical indexes. In zymography, immunohistology staining, immunofluorescence staining, and reactive oxygen species (ROS) analysis, TUNEL assay was used to examine the effects of IKKε on AAA progression in AAA mice. IKKε deficiency significantly inhibited inflammatory macrophage infiltration, matrix metalloproteinase (MMP) activity, ROS production, and vascular smooth muscle cell (VSMC) apoptosis. We used primary mouse aortic VSMC isolated from apolipoprotein E (Apoe) -/- and Apoe-/-IKKε -/- mice. Mechanistically, IKKε deficiency blunted the activation of the ERK1/2 pathway. The IKKε inhibitor, amlexanox, has the same impact in AAA. Our results demonstrate a critical role of IKKε in AAA formation induced by Ang II in Apoe-/- mice. Targeting IKKε may constitute a novel therapeutic strategy to prevent AAA progression.

Non-viral vector based gene transfection with human induced pluripotent stem cells derived cardiomyocytes.

Non-viral transfection of mammalian cardiomyocytes (CMs) is challenging. The current study aims to characterize and determine the non-viral vector based gene transfection efficiency with human induced pluripotent stem cells (hiPSCs) derived cardiomyocytes (hiPSC-CMs). hiPSC-CMs differentiated from PCBC hiPSCs were used as a cell model to be transfected with plasmids carrying green fluorescence protein (pGFP) using polyethylenimine (PEI), including Transporter 5 Transfection Reagent (TR5) and PEI25, and liposome, including lipofectamine-2000 (Lipo2K), lipofectamine-3000 (Lipo3K), and Lipofectamine STEM (LipoSTEM). The gene transfection efficiency and cell viability were quantified by flow cytometry. We found that the highest gene transfection efficiency in hiPSC-CMs on day 14 of contraction can be achieved by LipoSTEM which was about 32.5 ± 6.7%. However, it also cuased poor cell viability (60.1 ± 4.5%). Furthermore, a prolonged culture of (transfection on day 23 of contraction) hiPSC-CMs not only improved gene transfection (54.5 ± 8.9%), but also enhanced cell viability (74 ± 4.9%) by LipoSTEM. Based on this optimized gene transfection condition, the highest gene transfection efficiency was 55.6 ± 7.8% or 34.1 ± 4%, respectively, for P1C1 or DP3 hiPSC line that was derived from healthy donor (P1C1) or patient with diabetes (DP3). The cell viability was 80.8 ± 5.2% or 92.9 ± 2.24%, respectively, for P1C1 or DP3. LipoSTEM is a better non-viral vector for gene transfection of hiPSC-CMs. The highest pGFP gene transfection efficiency can reach >50% for normal hiPSC-CMs or >30% for diabetic hiPSC-CMs.

De Ritis ratio as a significant prognostic factor of international normalized ratio ≥4 in the initial 10 days of warfarin therapy.

Aim: To assess the relationship between the De Ritis ratio on admission and warfarin sensitivity in the initial 10 days of anticoagulation therapy. Methods: We retrospectively reviewed data from 906 patients who underwent heart valve replacement surgery. Results: A De Ritis ratio of 1.19 was identified as the optimal cutoff according to the ROC curve. Patients with a high De Ritis ratio achieved an international normalized ratio (INR) ≥4 more easily and earlier than those with a low De Ritis ratio in the initial 10 days of warfarin therapy. Multivariate analysis showed that a high De Ritis ratio was an independent predictor of an INR ≥4 (HR: 2.567; p < 0.001). Conclusion: A De Ritis ratio ≥1.19 on admission was significantly associated with an INR ≥4 in the initial 10 days of warfarin therapy among patients underwent heart valve replacement surgery.

Macrophage-Specific IκB Kinase α Contributes to Ventricular Remodelling and Dysfunction After Myocardial Infarction.

BACKGROUND: The IκB kinase (IKK) complex has been found to have critical functions in cancer and the immune system. In particular, IKKα, which is a member of the IKK complex, has been shown to influence the inflammatory response and malignant diseases. However, the role of IKKα in macrophages after myocardial infarction (MI) remains largely unknown. METHODS: Sham or MI operations were performed on macrophage-specific IKKɑ knockout (mIKKɑ-/-) mice and IKKɑflox/flox littermates. We ligated the left anterior descending coronary artery of the MI group and observed the results at 3, 7, and 30 days after MI. RESULTS: We discovered more severe cardiac dysfunction with reduced angiogenesis, fibrosis, and collagen deposition in mIKKɑ-/- than in IKKɑflox/flox. In addition, we also observed that macrophages in mIKKɑ-/- were easier to polarize to the M1 phenotype and expressed more proinflammatory factors than IKKɑflox/flox. Mechanistically, IKKα deficiency in macrophages inhibited the alternative nuclear factor-κB/RelB pathway and enhanced the MEK1/2/ERK1/2 pathway. CONCLUSIONS: Overall, our data identified IKKɑ in the heart as a novel mediator that protected the heart from a severe inflammatory response and attenuated ventricular remodelling after MI by negatively regulating macrophage polarization to the M1 phenotype. Therefore, IKKα may serve as a potential therapeutic target for treatment after MI.

I-κB kinase-ε knockout protects against angiotensin II induced aortic valve thickening in apolipoprotein E deficient mice.

Aortic stenosis (AS) is considered to be an actively regulated progress that involves similar pathophysiological processes as atherosclerosis. I-κB kinase-ε (IKKε) is a proinflammatory molecule involved in atherosclerosis. The objective of the present study was to define the role of IKKε in pathological valvular remodeling. Aortic valves (AVs) from 52 patients undergoing AV replacement (AS) and 13 patients undergoing heart transplant (Control) were analyzed. ApoE-/- mice (AK, n = 20) and ApoE-/-IKKε-/- mice (DK, n = 20) were generated and infused with saline or Ang II for 4 weeks. We found an upregulation of IKKε in human stenotic aortic valves compared to that in control AVs. Our results demonstrated that AK mice receiving AngII exhibited more advanced valvular remodeling and markedly increased IKKε expression. Conversely, loss of IKKε reduced adverse aortic valve thickening in response to Ang II, as measured by histological analyses. Furthermore, according to immunofluorescence analysis, Ang II resulted in obvious increases in the expression of α-SMA, TGF-ß and NF-κB pathway components in the AK group, especially in the thickened area, while these increases were blocked in the DK group. Moreover, IKKε was co-expressed with α-SMA in valvular interstitial cells in ApoE-/- mice after an AngII infusion. These data provide evidence that IKKε plays a key role in the development of valvular remodeling and that it may be a novel target for the treatment of AS.

Stem Cell Homing: a Potential Therapeutic Strategy Unproven for Treatment of Myocardial Injury.

Despite advances in the prevention and therapeutic modalities of ischemic heart disease, morbidity and mortality post-infarction heart failure remain big challenges in modern society. Stem cell therapy is emerging as a promising therapeutic strategy. Stem cell homing, the ability of stem cells to find their destination, is receiving more attention. Identification of specific cues and understanding the signaling pathways that direct stem cells to targeted destination will improve stem cell homing efficiency. This review discusses the cellular and molecular mechanism of stem cell homing at length in the light of literature and analyzes the problem and considerations of this approach as a treatment strategy for the treatment of ischemic heart disease clinically.

Risk factors for early death in primary malignant cardiac tumors: An analysis of over 40 years and 500 patients.

OBJECTIVES: To investigate risk factors contributing to early death in patients diagnosed with primary malignant cardiac tumors (PMCTs) and derive better understanding of these poorly characterized individuals. METHOD: Data from the Surveillance, Epidemiology and End-Results (SEER) registries on 564 patients diagnosed with PMCTs between 1973 and 2014 were analyzed. Early death was defined as survival of ≤3 months from the time of diagnosis. Two-tailed χ2 or fisher's exact test were used for association between categorical variables and occurrence of early death. Logistic regression analysis was used to assess independent risk factors of early death. Time trends in early death rates of PMCTs were described using scatter plot. RESULTS: Of the 564 patients with PMCTs, early death was identified in 214 individuals (37.9%). Patients with unspecified soft tissue sarcomas and blood vessel tumors had the highest risk of early death. Age > 80 years and non-consent for surgery were strong predictors of early death in all PMCT subtypes. In sarcomas, disadvantaged income was associated with an increase in early mortality, while black race was associated with a reduction in early mortality. In mesotheliomas and others, male sex was a risk factor for early mortality, while Hispanic ethnicity was associated with a reduction in early mortality. Percentages of early death slightly decreased over the past 40 years. CONCLUSIONS: Predictors of early death are primarily related to age older than 80 years, no surgery and specific histopathology types but also include disadvantaged socioeconomic status and male sex. Initiatives to identify those at risk and develop preventive interventions should be prioritized.

Association between apolipoprotein E genotype and warfarin response during initial anticoagulation.

Apolipoprotein E (APOE) genotypes are associated with warfarin dose requirements in various populations. Whether APOE genotypes mediate the warfarin response is unknown. The aim of this study was to evaluate the genetic contributions of different APOE genotypes to the early phase of anticoagulation in Han Chinese patients. We conducted a retrospective cohort study and assessed APOE genotypes, clinical characteristics, international normalized ratio (INR) responses, warfarin dose requirements and bleeding events in 429 Han Chinese patients. The study outcomes were the time to the first INR within the therapeutic range, the time to the first INR of more than 4, the INR response over time, and the warfarin dose requirement. Compared with patients with the ε3/ε3 genotype, patients with at least one ε4 allele had significantly longer times to the first INR of more than 4 during both the initial 20 days (P = 0.001, HR 2.9; 95%CI, 1.54-5.45) and the entire follow-up period (P < 0.001, HR 3.26; 95%CI,1.94-5.47), but this allele was not a significant predictor of the time to the first INR within the therapeutic range. No association was observed between the ε2 allele and INR response, and both the ε4 allele and the ε2 allele did not significantly affect the required warfarin dose during the follow-up. These observations suggest that genetic variants of APOE are associated with an increased risk of overanticoagulation among the Han Chinese population. However, these variants may not be useful in predicting warfarin maintenance dose requirements.

Cortistatin attenuates angiotensin II-induced abdominal aortic aneurysm through inactivation of the ERK1/2 signaling pathways.

Abdominal aortic aneurysm (AAA) is a fatal disease that is associated with chronic inflammation in the vessel wall. Cortistatin is implicated in inflammation, vascular smooth muscle cell migration and other cardiovascular pathologies. But, the hypothetical effect of cortistatin on AAA remains uncertain. We investigated the effect of cortistatin administration to angiotensin (Ang) II-induced AAA formation in apolipoprotein E deficient (Apoe-/-) mice. We showed that cortistatin administration significantly suppresses incidence and severity of AAA in Apoe-/- mice. A significant increase in macrophage infiltration, excretion of inflammatory cytokines, activities and expression levels of MMP2 and MMP9, reactive oxygen species levels and cell apoptosis in aneurysmal aortic wall of Apoe-/- mice infused with Ang-II, and these events were significantly alleviated by co-treatment with cortistatin. Mechanistic studies showed that the protective effects of cortistatin were related to the blocking of ERK1/2 signaling pathways, while does not was not actually affect JNK, P38 phosphorylation. In conclusion, cortistatin appears to play an essential role in the formation of AAA and indicate cortistatin may as novel therapeutic option for AAA.

Prevalence of primary cardiac tumor malignancies in retrospective studies over six decades: a systematic review and meta-analysis.

The incidence of patients diagnosed with primary malignant cardiac tumors (PMCTs) has increased greatly in the past few decades. Whether this rising prevalence is due to overdiagnosis or an increased malignancy rate of primary cardiac tumors (PCTs) remains unclear. Therefore, we performed a systematic review and meta-analysis of published retrospective studies to determine whether the malignancy rate has been increasing over time. Published studies containing relevant data between 1956 and 2014 were evaluated. Two authors searched for all retrospective studies that included patients diagnosed with PCT and PMCT. Two other investigators independently extracted the data, and discrepancies were resolved by consensus. A random-effects meta-analysis model and cumulative meta-analysis model were used to evaluate the pooled prevalence and trend of dynamic change in PCT malignancies. The effects of time, study period and sample size were studied using a logit-linear regression model with robust error variance and a time variable. Thirty-eight studies involving 5,586 patients were analyzed. The pooled prevalence of PMCT among the patients diagnosed with PCT was 9.9% (95% CI, 8.4% to 11.4%) (I2=70%; P< 0.001), and this prevalence has been stable since around 2003. In the regression model, the malignancy odds ratio remained stable from 1975 onward, and no time effect was observed. Our study confirms that PMCT is uncommon, and the prevalence of PCT malignancies remained stable in the past few decades. The clinically observed increase in incidence is unlikely to reflect a true population-level increase in tumorigenesis. This result strongly suggests that the observed increase in incidence of PMCT most likely reflects increased diagnostic detection over time.