Microbial mat compositions and localization patterns explain the virulence of black band disease in corals.

Black band disease (BBD) in corals is characterized by a distinctive, band-like microbial mat, which spreads across the tissues and often kills infected colonies. The microbial mat is dominated by cyanobacteria but also commonly contains sulfide-oxidizing bacteria (SOB), sulfate-reducing bacteria (SRB), and other microbes. The migration rate in BBD varies across different environmental conditions, including temperature, light, and pH. However, whether variations in the migration rates reflect differences in the microbial consortium within the BBD mat remains unknown. Here, we show that the micro-scale surface structure, bacterial composition, and spatial distribution differed across BBD lesions with different migration rates. The migration rate was positively correlated with the relative abundance of potential SOBs belonging to Arcobacteraceae localized in the middle layer within the mat and negatively correlated with the relative abundance of other potential SOBs belonging to Rhodobacteraceae. Our study highlights the microbial composition in BBD as an important determinant of virulence.

Isoproterenol loading transesophageal echocardiography in atrial fibrillation.

In patients with sludge or severe spontaneous echo contrast (SEC) in the left atrial appendage (LAA), cases with isoproterenol loading transesophageal echocardiography (ISP-TEE) have been reported to identify the presence of thrombus in the LAA. This study aimed to assess the validity and hemodynamic changes of ISP-TEE in the LAA. We prospectively enrolled patients with atrial fibrillation (AF) who underwent ISP-TEE. The degree of sludge/SEC was categorized as being either absent (grade 0), mild SEC (grade 1), moderate SEC (grade 2), severe SEC or sludge (grade 3). The hemodynamic evaluation was performed by measuring LAA flow velocity, LAA tissue Doppler imaging (LAA-TDI) velocity, and pulmonary vein systolic forward flow velocity (PVS). In total, 35 patients (mean age 71 ± 7 years; 71% male) underwent ISP-TEE. Among 35 patients, 30 patients had grade 3 or 2 SEC, 5 patients had grade 1 SEC. After ISP loading, 23 patients (66% of all patients) showed improved sludge/SEC and one patient was diagnosed with thrombus in the LAA. There were 25 patients with grade 1 SEC, or no SEC (classified as Group1), 10 patients had residual sludge or grade 2 to 3 SEC (classified as Group2) after ISP administration. LAA flow, LAA-TDI, and PVS velocities were significantly higher in group 1 than in group 2 after ISP administration. There was no complication during the examination and after 24 h and 3 months. ISP infusion may be a potential tool to recognize LAA thrombus under the sludge/SEC during TEE in AF.

Functional Evaluation of 3D Liver Models Labeled with Polysaccharide Functionalized Magnetic Nanoparticles.

Establishing a rapid in vitro evaluation system for drug screening is essential for the development of new drugs. To reproduce tissues/organs with functions closer to living organisms, in vitro three-dimensional (3D) culture evaluation using microfabrication technology has been reported in recent years. Culture on patterned substrates with controlled hydrophilic and hydrophobic regions (Cell-ableTM) can create 3D liver models (miniature livers) with liver-specific Disse luminal structures and functions. MRI contrast agents are widely used as safe and minimally invasive diagnostic methods. We focused on anionic polysaccharide magnetic iron oxide nanoparticles (Resovist®) and synthesized the four types of nanoparticle derivatives with different properties. Cationic nanoparticles (TMADM) can be used to label target cells in a short time and have been successfully visualized in vivo. In this study, we examined the morphology of various nanoparticles. The morphology of various nanoparticles showed relatively smooth-edged spherical shapes. As 3D liver models, we prepared primary hepatocyte-endothelial cell heterospheroids. The toxicity, CYP3A, and albumin secretory capacity were evaluated in the heterospheroids labeled with various nanoparticles. As the culture period progressed, the heterospheroids labeled with anionic and cationic nanoparticles showed lower liver function than non-labeled heterospheroids. In the future, there is a need to improve the method of creation of artificial 3D liver or to design a low-invasive MRI contrast agent to label the artificial 3D liver.

Digital workflows for pathological assessment of rat estrous cycle stage using images of uterine horn and vaginal tissue.

Assessment of the estrous cycle of mature female mammals is an important component of verifying the efficacy and safety of drug candidates. The common pathological approach of relying on expert observation has several drawbacks, including laborious work and inter-viewer variability. The recent advent of image recognition technologies using deep learning is expected to bring substantial benefits to such pathological assessments. We herein propose 2 distinct deep learning-based workflows to classify the estrous cycle stage from tissue images of the uterine horn and vagina, respectively. These constructed models were able to classify the estrous cycle stages with accuracy comparable with that of expert pathologists. Our digital workflows allow efficient pathological assessments of the estrous cycle stage in rats and are thus expected to accelerate drug research and development.

Lipomatosis of axillary lymph nodes in a cynomolgus monkey (Macaca fascicularis).

Lipomatosis of lymph nodes is defined as the replacement of the lymphatic parenchyma by adipose tissue which grows in the node from the hilus toward the cortical zone. In humans, it is considered as part of the normal aging process and is common in obese patients, but there are no reports in non-human primates. In this report, we describe the first case of lymph node lipomatosis in the bilateral axillary lymph nodes of a young adult cynomolgus monkey. Macroscopically, there were no apparent abnormalities in the axillary lymph nodes on either side, and their volumes were unchanged. At the cut surface, pale yellow fat-like tissue was observed in the medullary area. Histopathologically, well differentiated adipocytes replaced a large part of the lymphatic parenchyma in the area from the hilus to the medulla without any malignant findings. Based on these findings, the patient was diagnosed with lipomatosis of the lymph nodes.

Intracerebral hemorrhage due to vasculitis following COVID-19 vaccination: a case report.

Several vaccines have been approved worldwide for the prevention of morbidity and mortality against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). However, the development of these vaccines has raised concerns regarding their adverse effects. Herein, we report the first case of intracerebral hemorrhage (ICH) due to vasculitis after the first dose of mRNA vaccine (BNT162b2, Pfizer/BioN-Tech). Although this case cannot demonstrate a direct relationship between COVID-19 vaccination and vasculitis, the clinical and histological features of this patient are highly consistent with the adverse effects of COVID-19 vaccine.

Double-crescent sign as a predictor of chronic subdural hematoma recurrence following burr-hole surgery.

OBJECTIVE: Subdural hygroma has been reported as a causative factor in the development of a chronic subdural hematoma (CSDH) following a head trauma and/or neurosurgical procedure. In some CSDH cases, the presence of a 2-layered space delineated by the same or similar density of CSF surrounded by a superficial, residual hematoma is seen on CT imaging after evacuation of the hematoma. The aims of the present study were to test the hypothesis that the double-crescent sign (DCS), a unique imaging finding described here, is associated with the postoperative recurrence of CSDH, and to investigate other factors that are related to CSDH recurrence. METHODS: The authors retrospectively analyzed data from 278 consecutive patients who underwent single burr-hole surgery for CSDH between April 2012 and March 2017. The DCS was defined as a postoperative CT finding, characterized by the following 2 layers: a superficial layer demonstrating residual hematoma after evacuation of the CSDH, and a deep layer between the brain's surface and the residual hematoma, depicted as a low-density space. Correlation of the recurrence of CSDH with the DCS was evaluated by multivariate logistic regression modeling. The authors also investigated other classic predictive factors including age, sex, past history of head injury, hematoma laterality, anticoagulant and antiplatelet therapy administration, preoperative hematoma volume, postoperative residual hematoma volume, and postoperative brain reexpansion rate. RESULTS: A total of 277 patients (320 hemispheres) were reviewed. Fifty (18.1%) of the 277 patients experienced recurrence of CSDH within 3 months of surgery. CSDH recurred within 3 months of surgery in 32 of the 104 hemispheres with a positive DCS. Multivariate logistic analyses revealed that the presence of the DCS (OR 3.36, 95% CI 1.72-6.57, p < 0.001), large postoperative residual hematoma volume (OR 2.88, 95% CI 1.24-6.71, p = 0.014), anticoagulant therapy (OR 3.03, 95% CI 1.02-9.01, p = 0.046), and bilateral hematoma (OR 3.57, 95% CI 1.79-7.13, p < 0.001) were significant, independent predictors of CSDH recurrence. CONCLUSIONS: In this study, the authors report that detection of the DCS within 7 days of surgery is an independent predictive factor for CSDH recurrence. They therefore advocate that clinicians should carefully monitor patients for postoperative DCS and subsequent CSDH recurrence.

Long-term Cryopreservation of Human and other Mammalian Cells at -80 °C for 8 Years.

Freezing is recognized as the most effective method of maintaining a stable supply of various cell types for long-term storage. However, cells might be damaged by environmental changes during the freezing process. There are various factors that influence the function of cells cultured after cryopreservation and thawing. These factors include cryopreservation solutions, biomaterials, freezing methods, and the freezing and preservation temperatures. There is also a risk of infection with mycoplasma in liquid nitrogen phase. Therefore, it is necessary to consider more useful and safe methods for freezing and storing various cells. In this study, we investigated the effects of temperature during long-term storage (8 years at -80 °C and in liquid nitrogen phase) on the quality of various cells (human hepatocellular carcinoma cells, bovine carotid artery normal endothelial cells, mouse fibroblast cells 3T3, and mouse embryo fibroblast cells STO). We examined the cell viability of cryopreserved human hepatocellular carcinoma cells at -80 °C using culture medium containing 10% DMSO, Cell Banker 1, and Cell Banker 2 as cryopreservation solutions. Among these solutions, Cell Banker 1 showed the highest efficiency. The viability of human hepatocellular carcinoma and bovine carotid artery normal endothelial cells in the Cell Banker 1 stored at -80 °C was over 90%, which was the same as that in liquid nitrogen phase. The cells stored at -80 °C had a morphology similar to that of the cells stored at liquid nitrogen phase. The proliferation of cells stored at -80 °C and in liquid nitrogen phase was not significantly different. Furthermore, none of the cells were infected with mycoplasma. There was no marked difference in the albumin secretion between the human hepatocellular carcinoma cells stored at -80 °C and those in liquid nitrogen phase. The short tandem repeats of the human hepatocellular carcinoma cells stored at -80 °C were identical to those stored in liquid nitrogen phase. In this report, various cells stored long-term at -80 °C were able to be used effectively after long-term storage. These findings can be applied to drug discovery, cell medicine, and cell therapy.

Enhanced Adipogenic Differentiation of Human Adipose-Derived Stem Cells in an In Vitro Microenvironment: The Preparation of Adipose-Like Microtissues Using a Three-Dimensional Culture.

The application of stem cells for cell therapy has been extensively studied in recent years. Among the various types of stem cells, human adipose tissue-derived stem cells (ASCs) can be obtained in large quantities with relatively few passages, and they possess a stable quality. ASCs can differentiate into a number of cell types, such as adipose cells and ectodermal cells. We therefore focused on the in vitro microenvironment required for such differentiation and attempted to induce the differentiation of human stem cells into microtissues using a microelectromechanical system. We first evaluated the adipogenic differentiation of human ASC spheroids in a three-dimensional (3D) culture. We then created the in vitro microenvironment using a 3D combinatorial TASCL device and attempted to induce the adipogenic differentiation of human ASCs. The differentiation of human ASC spheroids cultured in maintenance medium and those cultured in adipocyte differentiation medium was evaluated via Oil red O staining using lipid droplets based on the quantity of accumulated triglycerides. The differentiation was confirmed in both media, but the human ASCs in the 3D cultures contained higher amounts of triglycerides than those in the 2D cultures. In the short culture period, greater adipogenic differentiation was observed in the 3D cultures than in the 2D cultures. The 3D culture using the TASCL device with adipogenic differentiation medium promoted greater differentiation of human ASCs into adipogenic lineages than either a 2D culture or a culture using a maintenance medium. In summary, the TASCL device created a hospitable in vitro microenvironment and may therefore be a useful tool for the induction of differentiation in 3D culture. The resultant human ASC spheroids were "adipose-like microtissues" that formed spherical aggregation perfectly and are expected to be applicable in regenerative medicine as well as cell transplantation.

Prognostic Implications of Non-Invasive Vascular Function Tests in High-Risk Atherosclerosis Patients.

BACKGROUND: The aim of this study was to assess the role of clinically available vascular function tests as predictors of cardiovascular events and decline in kidney function. METHODS AND RESULTS: One hundred and fourteen patients who had at least 2 cardiovascular risk factors were recruited for vascular function assessment including ankle-brachial blood pressure index (ABI), brachial-ankle pulse wave velocity (baPWV), cardio-ankle vascular index (CAVI) and flow-mediated vasodilatation (%FMD). During a median period of 51 months, 35 patients reached the primary endpoint (29 cardiovascular events and 6 cardiac deaths), and 30 patients reached the secondary endpoint (decline in kidney function: defined as a 5% per year decline of estimated glomerular filtration rate). In sequential Cox models, a model on the basis of the Framingham risk score, hemoglobin, and high-sensitivity C-reactive protein (chi-squared, 16.6) was improved by the ABI (chi-squared: 21.5; P=0.047). The baPWV (hazard ratio: 1.42 per 1 SD increase; P=0.025) and the CAVI (hazard ratio: 1.52 per 1 SD increase; P=0.040) were associated with the secondary endpoint. The %FMD was only slightly associated with the primary and secondary endpoints. CONCLUSIONS: Both ABI and baPWV are significantly associated with future cardiovascular events in high-risk patients with cardiovascular disease. The predictive capabilities of these parameters are greater than that of other parameters in this cohort.

Comparison of Tricuspid Annular Plane Systolic Excursion in Patients With Atrial Fibrillation Versus Sinus Rhythm.

Echocardiography now plays a central guiding role in the management of patients with atrial fibrillation (AF). However, the current guidelines mention little about the presence AF during the assessment of echocardiographic variables in the clinical setting. AF itself may impact on tricuspid annular plane systolic excursion (TAPSE) as a right ventricular systolic function compared with sinus rhythm (SR). The aim of this study was to compare and assess the echocardiographic parameters including TAPSE in patients with AF and SR. From January 1, 2013, to September 30, 2014, patients with AF without any cardiovascular disease were retrospectively evaluated using echocardiography. Age-, gender-, and left ventricular ejection fraction-matched patients with SR were selected from our database on the basis of a comprehensive history, physical examination, and echocardiographic findings. During the study period, we identified 239 patients with AF (74 ± 9 years; 65% men) and without any cardiac disease who underwent echocardiography. We also included 281 patients in the SR group (74 ± 8 years; 67% men). In all study subjects, TAPSE in AF was smaller than in SR regardless of age (17 ± 3 vs 20 ± 3 mm, p <0.001). In the stepwise multiple regression model, TAPSE was strongly associated with the presence of AF (standardized ß = -0.362, p <0.001) and stroke volume index (standardized ß = 0.173, p <0.001) after adjustment for age, gender, heart rate, left ventricular ejection fraction, and tricuspid regurgitant grade. In conclusions, patients with AF had lower TAPSE than those with SR regardless of age. When we assess TAPSE in the clinical setting, we must pay attention to the presence of AF.

Correlation Between Arteriosclerosis and Periodontal Condition Assessed by Lactoferrin and α1-Antitrypsin Levels in Gingival Crevicular Fluid.

Patients with periodontal disease exhibit exacerbated atherosclerosis, aortic stiffness, or vascular endothelial dysfunction. However, in a recent scientific statement, the American Heart Association noted that neither has periodontal disease been proven to cause atherosclerotic vascular disease nor has the treatment of periodontal disease been proven to prevent atherosclerotic vascular disease. Therefore, the aim of the present study was to examine the correlation between periodontal condition and arteriosclerosis in patients with coronary artery disease (CAD), which is usually accompanied by systemic arteriosclerosis.We measured levels of gingival crevicular fluid lactoferrin (GCF-Lf) and α1-antitrypsin (GCF-AT) in 72 patients (67 ± 8 years, 56 men) with CAD. Furthermore, we evaluated the maximum intima-media thickness (max IMT) and plaque score of the carotid arteries as well as brachial-ankle pulse wave velocity (baPWV) and flow-mediated dilation (FMD) of the brachial artery, each of which is a parameter for determining arteriosclerosis status. The average level of GCF-Lf was 0.29 ± 0.36 µg/mL and that of GCF-AT was 0.31 ± 0.66 µg/mL, with significant correlation between the two (r = 0.701, P < 0.001). No significant difference in GCF-Lf and GCF-AT levels was observed between patients with single-, double-, and triple-vessel CAD. There were no significant correlations between the arteriosclerosis parameters (ie, max IMT, plaque score, baPWV, and FMD) and GCF-Lf or GCF-AT.No correlation between the GCF biomarkers and the severity of arteriosclerosis was detected. This result may suggest that worsening of the periodontal condition assessed by GCF biomarkers is not a major potential risk factor for arteriosclerosis.

Pulmonary embolism due to right atrial free-floating thrombus during echocardiographic examination: a case of a pulmonary saddle thrombus.

A 69-year-old female with polymyositis was referred to our hospital with a chief complaint of dyspnea. Transthoracic echocardiography showed right ventricular overloading. In addition to two-dimensional echocardiography, observation of the abnormal free-floating string-like mass by three-dimensional echocardiography provided superior visualization of the features of the mass which protruded into the right ventricle across the tricuspid valve during diastole. These findings enabled us to confirm the diagnosis of venous thrombus. The thrombus disappeared during the echocardiographic examination. Multidetector-row computed tomography showed a string-like thrombus across the bifurcation of the main pulmonary artery. Anticoagulation therapy was initiated with heparin and warfarin, and fondaparinux was started on the fourth day. Three-dimensional echocardiography was useful in characterizing the motion and extent of the thrombus.

Clinical Utility of Measuring Epicardial Adipose Tissue Thickness with Echocardiography Using a High-Frequency Linear Probe in Patients with Coronary Artery Disease.

BACKGROUND: The relationship between epicardial adipose tissue (EAT) and coronary artery disease (CAD) has recently attracted a great deal of attention in the medical community. The objective of this study was to determine whether measuring EAT thickness in the anterior interventricular groove (AIG) using echocardiography is feasible and whether this index can be a marker of CAD. METHODS: A total of 311 patients (mean age, 67 ± 11 years; 208 men) who underwent coronary angiography between December 2011 and December 2013 were prospectively enrolled. EAT-AIG thickness and EAT thickness on the free wall of the right ventricle (RV) were measured in systole using a high-frequency linear probe. Seventy-one patients who underwent multidetector-row computed tomography were enrolled to validate the method for measuring EAT thickness using echocardiography. Subjects were divided into two groups, those with and without significant coronary stenosis, on the basis of findings on coronary angiography (≥ 75% luminal narrowing). RESULTS: EAT-AIG thickness measured using echocardiography was validated by computed tomography. EAT-AIG thickness was strongly correlated with EAT volume (r = 0.714, P < .001). The CAD group had thicker EAT-AIG than the non-CAD group (8.3 ± 3.0 vs 6.3 ± 2.5 mm, P < .001). EAT-RV thickness was greater in the CAD group than in the non-CAD group (5.0 ± 2.1 vs 4.4 ± 2.3 mm, P = .009) as well. The area under the curve on receiver operating characteristic curve analysis of EAT-AIG thickness for predicting CAD was 0.704, which was higher than the EAT-RV thickness. CONCLUSIONS: Measuring EAT thickness using echocardiography with a high-frequency linear probe was validated with computed tomography. EAT-AIG was thicker in the CAD group than in the non-CAD group, as was EAT-RV thickness. This noninvasive index may have potential as a diagnostic marker for predicting coronary atherosclerosis.

Age- and gender-specific changes of tricuspid annular motion velocities in normal hearts.

BACKGROUND: Mitral annular motion (MAM) and tricuspid annular motion (TAM) velocities obtained by pulsed tissue Doppler echocardiography have been used to evaluate left ventricular (LV) and right ventricular (RV) functions. Although TAM velocity has been clinically applied for evaluating various cardiac diseases, the effects of age and gender remain unclear. Therefore, we aimed to determine the effects of age and gender on TAM velocity in normal hearts. METHODS: We randomly selected 265 subjects (mean age, 59 years; range, 20-89 years) without abnormal clinical, electrocardiographic, and echocardiographic findings from a pool of subjects who had undergone transthoracic echocardiography. They were classified into four age groups: 20-39, 40-59, 60-79, and >80 years. Pulsed wave Doppler was applied to obtain MAM velocity of the lateral side and TAM velocity of the RV free wall side. The peak systolic (s'), early diastolic (e'), and atrial systolic (a') velocities of MAM and TAM were measured in all subjects. RESULTS: While MAM-s' (r=-0.267, p<0.001) correlated with age, TAM-s' did not (p=0.755). TAM-s' in any age groups had no significant gender differences. TAM-e' (r=-0.447, p<0.001) and MAM-e' (r=-0.724, p<0.001) correlated with age, respectively. In those aged 40-59 years, both TAM-e' (p=0.002) and MAM-e' (p=0.048) in females were significantly higher than those in males. The gender differences diminished in the ≥60 years age groups. CONCLUSIONS: There was no age-associated decline in TAM-s', while TAM-e' varied with age and gender as did MAM-e'. Although the same criteria for the TAM-s' can be used for identifying abnormal RV systolic function regardless of age and gender, age and gender differences must be considered when one utilizes the TAM-e' for the diagnosis or management of cardiovascular disease.

Tricuspid annular motion velocity as a differentiation index of hypertrophic cardiomyopathy from hypertensive heart disease.

BACKGROUND: Hypertensive heart disease (HHD) and hypertrophic cardiomyopathy (HCM) are the most frequently encountered entities presenting left ventricular hypertrophy in routine echocardiographic examination, and their differentiation is sometimes difficult. Abnormalities in right ventricular (RV) myocardium have been reported frequently in patients with HCM more than in those with HHD. We therefore hypothesized that tricuspid annular motion (TAM) velocity determined by pulsed tissue Doppler echocardiography can be used to detect RV dysfunction in HCM and discriminate these etiologies. METHODS: TAM velocities were compared among clinically stable patients with 60 HCM and 60 HHD patients as well as 60 age-matched healthy controls. Peak systolic, early diastolic (TAM-e'), and atrial systolic velocities were measured. RV myocardial performance index was measured by tissue Doppler method. To more accurately differentiate HCM from HHD, electrocardiographic findings and brain natriuretic peptide levels, which can both be examined simply and noninvasively, were investigated in addition to echocardiography. RESULTS: RV wall thickness of the HCM group was greater than the HHD group (p=0.092), while there was no significant difference in RV myocardial performance index between the HCM and HHD groups (p=0.606). TAM-e' was significantly lower in the HCM group than in HHD and control groups (p=0.001). To differentiate HCM from HHD, TAM-e' was a powerful predictor as per multivariate logistic regression analysis (hazard ratio, 0.665; p<0.001) of parameters other than those of left ventricular parameters, and the area under the receiver operating characteristic curve (AUC) was 0.686 and the best cut-off value was ≤8.0cm/s (62% sensitivity, 65% specificity). Multivariate logistic analysis revealed that electrocardiographic ST-T changes were the next most effective marker for differentiating HCM after TAM-e'. When TAM-e' and ST-T changes were combined, the AUC increased to 0.748. CONCLUSIONS: TAM-e' is a potentially useful index to differentiate HCM from HHD.

Optimal Analysis of Left Atrial Strain by Speckle Tracking Echocardiography: P-wave versus R-wave Trigger.

BACKGROUND: Left atrial (LA) strain analysis using speckle tracking echocardiography is useful for assessing LA function. However, there is no established procedure for this method. Most investigators have determined the electrocardiographic R-wave peak as the starting point for LA strain analysis. To test our hypothesis that P-wave onset should be used as the starting point, we measured LA strain using 2 different starting points and compared the strain values with the corresponding LA volume indices obtained by three-dimensional (3D) echocardiography. METHODS: We enrolled 78 subjects (61 ± 17 years, 25 males) with and without various cardiac diseases in this study and assessed global longitudinal LA strain by two-dimensional speckle tracking strain echocardiography using EchoPac software. We used either R-wave peak or P-wave onset as the starting point for determining LA strains during the reservoir (Rres, Pres), conduit (Rcon, Pcon), and booster pump (Rpump, Ppump) phases. We determined the maximum, minimum, and preatrial contraction LA volumes, and calculated the LA total, passive, and active emptying fractions using 3D echocardiography. RESULTS: The correlation between Pres and LA total emptying fraction was better than the correlation between Rres and LA total emptying fraction (r = 0.458 vs. 0.308, P = 0.026). Pcon and Ppump exhibited better correlation with the corresponding 3D echocardiographic parameters than Rcon (r = 0.560 vs. 0.479, P = 0.133) and Rpump (r = 0.577 vs. 0.345, P = 0.003), respectively. CONCLUSIONS: LA strain in any phase should be analyzed using P-wave onset as the starting point rather than R-wave peak.

Three-Dimensional In Vitro Hepatic Constructs Formed Using Combinatorial Tapered Stencil for Cluster Culture (TASCL) Device.

Attempts to create artificial liver tissue from various cells have been reported as an alternative method for liver transplantation and pharmaceutical testing. In the construction of artificial liver tissue, the selection of the cell source is the most important factor. However, if an appropriate environment (in vitro/in vivo) cannot be provided for various cells, it is not possible to obtain artificial liver tissue with the desired function. Therefore, we focused on the in vitro environment and produced liver tissues using MEMS technology. In the present study, we report a combinatorial TASCL device to prepare 3D cell constructs in vitro. The TASCL device was fabricated with an overall size of 10 mm × 10 mm with microwells and a top aperture (400 µm × 400 µm, 600 µm × 600 µm, 800 µm × 800 µm) and bottom aperture (40 µm × 40 µm, 80 µm × 80 µm, 160 µm × 160 µm) per microwell. The TASCL device can be easily installed on various culture dishes with tweezers. Using plastic dishes as the bottom surface of the combinatorial TASCL device, 3D hepatocyte constructs of uniform sizes (about ɸ 100 µm-ɸ 200 µm) were produced by increasing the seeding cell density of primary mouse hepatocytes. The 3D hepatocyte constructs obtained using the TASCL device were alive and secreted albumin. On the other hand, partially adhered primary mouse hepatocytes exhibited a cobblestone morphology on the collagen-coated bottom of the individual microwells using the combinatorial TASCL device. By changing the bottom substrate of the TASCL device, the culture environment of the cell constructs was easily changed to a 3D environment. The combinatorial TASCL device described in this report can be used quickly and simply. This device will be useful for preparing hepatocyte constructs for application in drug screening and cell medicine.