Vascular dysfunction in hemorrhagic viral fevers: opportunities for organotypic modeling.

The hemorrhagic fever viruses (HFVs) cause severe or fatal infections in humans. Named after their common symptom hemorrhage, these viruses induce significant vascular dysfunction by affecting endothelial cells, altering immunity, and disrupting the clotting system. Despite advances in treatments, such as cytokine blocking therapies, disease modifying treatment for this class of pathogen remains elusive. Improved understanding of the pathogenesis of these infections could provide new avenues to treatment. While animal models and traditional 2D cell cultures have contributed insight into the mechanisms by which these pathogens affect the vasculature, these models fall short in replicatingin vivohuman vascular dynamics. The emergence of microphysiological systems (MPSs) offers promising avenues for modeling these complex interactions. These MPS or 'organ-on-chip' models present opportunities to better mimic human vascular responses and thus aid in treatment development. In this review, we explore the impact of HFV on the vasculature by causing endothelial dysfunction, blood clotting irregularities, and immune dysregulation. We highlight how existing MPS have elucidated features of HFV pathogenesis as well as discuss existing knowledge gaps and the challenges in modeling these interactions using MPS. Understanding the intricate mechanisms of vascular dysfunction caused by HFV is crucial in developing therapies not only for these infections, but also for other vasculotropic conditions like sepsis.

A perfused multi-well bioreactor platform to assess tumor organoid response to a chemotherapeutic gradient.

There is an urgent need to develop new therapies for colorectal cancer that has metastasized to the liver and, more fundamentally, to develop improved preclinical platforms of colorectal cancer liver metastases (CRCLM) to screen therapies for efficacy. To this end, we developed a multi-well perfusable bioreactor capable of monitoring CRCLM patient-derived organoid response to a chemotherapeutic gradient. CRCLM patient-derived organoids were cultured in the multi-well bioreactor for 7 days and the subsequently established gradient in 5-fluorouracil (5-FU) concentration resulted in a lower IC50 in the region near the perfusion channel versus the region far from the channel. We compared behaviour of organoids in this platform to two commonly used PDO culture models: organoids in media and organoids in a static (no perfusion) hydrogel. The bioreactor IC50 values were significantly higher than IC50 values for organoids cultured in media whereas only the IC50 for organoids far from the channel were significantly different than organoids cultured in the static hydrogel condition. Using finite element simulations, we showed that the total dose delivered, calculated using area under the curve (AUC) was similar between platforms, however normalized viability was lower for the organoid in media condition than in the static gel and bioreactor. Our results highlight the utility of our multi-well bioreactor for studying organoid response to chemical gradients and demonstrate that comparing drug response across these different platforms is nontrivial.

Extracellular matrix modulates T cell clearance of malignant cells in vitro.

Despite the success of T cell checkpoint therapies, breast cancers rarely express these immunotherapy markers and are believed to be largely "immune cold" with limited inflammation and immune activation. The reason for this limited immune activation remains poorly understood. We sought to determine whether extracellular matrix substrate could contribute to this limited immune activation. Specifically, we asked whether extracellular matrix could alter T cell cytotoxicity against malignant mammary gland carcinoma cells (MCC) in a setup designed to promote maximal T cell efficacy (i.e., rich media with abundant IL2, high ratio of T cells to MCC). We observed that T cell clearance of MCC varied from 0% in collagen 4 or 6 conditions to almost 100% in fibronectin or vitronectin. Transcriptomics revealed that T cell function was defective in MCC/T cell cocultures on collagen 4 (Col4), potentially corresponding to greater expression of cytokines MCC cultured in this environment. In contrast, transcriptomics revealed an effective, exhausted phenotype on vitronectin. The observation that Col4 induces T cell suppression suggests that targeting tumor-ECM interactions may permit new approaches for utilizing immunotherapy in tumors which do not provoke a strong immune response.

Performance of three-dimensional printed nasopharyngeal swabs for COVID-19 testing.

ABSTRACT: At the start of the COVID-19 pandemic, the US faced nationwide shortages of nasopharyngeal swabs due to both overwhelmed supply chains and an increase in demand. To address this shortfall, multiple 3D printed swabs were ultimately produced and sold for COVID-19 testing. In this work, we present a framework for mechanical and functional bench-testing of nasopharyngeal swabs using standard and widely available material testing equipment. Using this framework, we offer a comprehensive, quantitative comparison of the 3D printed swabs to benchmark their performance against traditional flocked swabs. The test protocols were designed to emulate the clinical use of the nasopharyngeal swabs and to evaluate potential failure modes. Overall, the 3D printed swabs performed comparably to, or outperformed, the traditional swabs in all mechanical tests. While traditional swabs outperformed some of the new 3D printed swabs in terms of sample uptake and retention, similar amounts of RNA were recovered from both 3D printed and traditional swabs.

Go with the flow: modeling unique biological flows in engineered in vitro platforms.

Interest in recapitulating in vivo phenomena in vitro using organ-on-a-chip technology has grown rapidly and with it, attention to the types of fluid flow experienced in the body has followed suit. These platforms offer distinct advantages over in vivo models with regards to human relevance, cost, and control of inputs (e.g., controlled manipulation of biomechanical cues from fluid perfusion). Given the critical role biophysical forces play in several tissues and organs, it is therefore imperative that engineered in vitro platforms capture the complex, unique flow profiles experienced in the body that are intimately tied with organ function. In this review, we outline the complex and unique flow regimes experienced by three different organ systems: blood vasculature, lymphatic vasculature, and the intestinal system. We highlight current state-of-the-art platforms that strive to replicate physiological flows within engineered tissues while introducing potential limitations in current approaches.

Projection Microstereolithographic Microbial Bioprinting for Engineered Biofilms.

Microbes are critical drivers of all ecosystems and many biogeochemical processes, yet little is known about how the three-dimensional (3D) organization of these dynamic organisms contributes to their overall function. To probe how biofilm structure affects microbial activity, we developed a technique for patterning microbes in 3D geometries using projection stereolithography to bioprint microbes within hydrogel architectures. Bacteria were printed and monitored for biomass accumulation, demonstrating postprint viability of cells using this technique. We verified our ability to integrate biological and geometric complexity by fabricating a printed biofilm with two E. coli strains expressing different fluorescence. Finally, we examined the target application of microbial absorption of metal ions to investigate geometric effects on both the metal sequestration efficiency and the uranium sensing capability of patterned engineered Caulobacter crescentus strains. This work represents the first demonstration of the stereolithographic printing of microbials and presents opportunities for future work of engineered biofilms and other complex 3D structured cultures.

Investigating the Interaction Between Circulating Tumor Cells and Local Hydrodynamics via Experiment and Simulations.

INTRODUCTION: The biological and mechanical properties of circulating tumor cells (CTCs) in combination with the hemodynamics affect the preference of metastatic sites in the vasculature. Despite the extensive literature on the effects of biological properties on cell adhesion, the effects of hydrodynamic forces on primary attachment remains an active area of research. Using simulations in conjunction with experimentation, we provide new insight into the interplay of CTCs dynamics and local hydrodynamics. METHODS: A flow experiment of CTC attachment was performed within a bioprinted, double branching endothelialized vessel. Simulations of fluid flow and CTC transport in the reconstructed and idealized bifurcated vessel were respectively performed by HARVEY, our in-house massively parallel computational fluid dynamics solver. HARVEY is based on the lattice Boltzmann and finite element methods to model the fluid and cells dynamics. The immersed boundary method is employed for resolving the fluid-structure interaction. RESULTS: CTC attachment was quantified experimentally at all regions of the complex vessel. The results demonstrate a clear preference for CTCs to attach at the branch points. To elucidate the effect of the vessel topology on the location of attachment, a fluid-only simulation was performed assessing the differences in the hydrodynamics along the vessel. CTC transport in idealized bifurcated vessels was subsequently studied to examine the effects of cell deformability on the local hydrodynamics patterns and, thus, the preference of attachment sites. CONCLUSIONS: The current work provides evidence on the correlation of the hydrodynamics forces arising from the vessel topology and CTC properties on the attachment regions.

Three-dimensional bioprinting of aneurysm-bearing tissue structure for endovascular deployment of embolization coils.

Various types of embolization devices have been developed for the treatment of cerebral aneurysms. However, it is challenging to properly evaluate device performance and train medical personnel for device deployment without the aid of functionally relevant models. Currentin vitroaneurysm models suffer from a lack of key functional and morphological features of brain vasculature that limit their applicability for these purposes. These features include the physiologically relevant mechanical properties and the dynamic cellular environment of blood vessels subjected to constant fluid flow. Herein, we developed three-dimensionally (3D) printed aneurysm-bearing vascularized tissue structures using gelatin-fibrin hydrogel of which the inner vessel walls were seeded with human cerebral microvascular endothelial cells (hCMECs). The hCMECs readily exhibited cellular attachment, spreading, and confluency all around the vessel walls, including the aneurysm walls. Additionally, thein vitroplatform was directly amenable to flow measurements via particle image velocimetry, enabling the direct assessment of the vascular flow dynamics for comparison to a 3D computational fluid dynamics model. Detachable coils were delivered into the printed aneurysm sac through the vessel using a microcatheter and static blood plasma clotting was monitored inside the aneurysm sac and around the coils. This biomimeticin vitroaneurysm model is a promising method for examining the biocompatibility and hemostatic efficiency of embolization devices and for providing hemodynamic information which would aid in predicting aneurysm rupture or healing response after treatment.

Macromolecular gelatin properties affect fibrin microarchitecture and tumor spheroid behavior in fibrin-gelatin gels.

The biophysical properties of extracellular matrices (ECM) are known to regulate cell behavior, however decoupling cell behavior changes due to the relative contributions of material microstructure versus biomechanics or nutrient permeability remains challenging, especially within complex, multi-material matrices. We developed four gelatin-fibrin interpenetrating network (IPN) formulations which are identical in composition but possess variable gelatin molecular weight distributions, and display differences in microstructure, biomechanics, and diffusivity. In this work we interrogate the response of multicellular tumor spheroids to these IPN formulations and found that a high stiffness, gelatin-network dominated IPNs impeded remodeling and invasion of multicellular tumor spheroids; whereas relatively lower stiffness, fibrin-network dominated IPNs permitted protease-dependent remodeling and spheroid invasion. Cell proliferation correlated to nutrient diffusivity across tested IPN formulations. These findings demonstrate the complexity of ECM IPNs, relative to single polymer matrices, and highlight that cell response does not derive from a single aspect of the ECM, but rather from the interplay of multiple biomechanical properties. The methodology developed here represents a framework for future studies which aim to characterize cellular phenotypic responses to biophysical cues present within complex, multi-material matrices.

Comparative Molecular Analysis of Cancer Behavior Cultured In Vitro, In Vivo, and Ex Vivo.

Current pre-clinical models of cancer fail to recapitulate the cancer cell behavior in primary tumors primarily because of the lack of a deeper understanding of the effects that the microenvironment has on cancer cell phenotype. Transcriptomic profiling of 4T1 murine mammary carcinoma cells from 2D and 3D cultures, subcutaneous or orthotopic allografts (from immunocompetent or immunodeficient mice), as well as ex vivo tumoroids, revealed differences in molecular signatures including altered expression of genes involved in cell cycle progression, cell signaling and extracellular matrix remodeling. The 3D culture platforms had more in vivo-like transcriptional profiles than 2D cultures. In vivo tumors had more cells undergoing epithelial-to-mesenchymal transition (EMT) while in vitro cultures had cells residing primarily in an epithelial or mesenchymal state. Ex vivo tumoroids incorporated aspects of in vivo and in vitro culturing, retaining higher abundance of cells undergoing EMT while shifting cancer cell fate towards a more mesenchymal state. Cellular heterogeneity surveyed by scRNA-seq revealed that ex vivo tumoroids, while rapidly expanding cancer and fibroblast populations, lose a significant proportion of immune components. This study emphasizes the need to improve in vitro culture systems and preserve syngeneic-like tumor composition by maintaining similar EMT heterogeneity as well as inclusion of stromal subpopulations.

Percutaneous Inserted Venous Catheter via Femoral Vein in Extremely Low-Birth-Weight Infants: A Single-Center Experience.

OBJECTIVE: This study aimed to assess the applicability of the insertion of small diameter catheters through the femoral vein in extremely low-birth-weight (ELBW) infants. STUDY DESIGN: All femoral small diameter catheters (Silastic or femoral arterial catheter [FAC]) inserted in ELBW infants in a tertiary level neonatal intensive care unit were retrospectively reviewed. Success rate, dwelling time, and percutaneously inserted central venous catheter-related complications were recorded. RESULTS: Thirteen small diameter catheters were inserted in seven ELBW infants. Mean gestational age at birth was 25+3 weeks (standard deviation [SD] ± 2.12) and mean birth weight was 686 g (SD ± 204.9). Mean weight at the first time of insertion was 1,044 g (SD ± 376.3). In two occasions, a FAC was used instead of a Silastic. In most cases (11/13, 84.6%), the patient was intubated prior to the procedure. The mean dwelling time was 16.7 days (SD ± 9.8). Most of the inserted small diameter catheters were removed electively (8/12, 66.7%), except for one episode of clinical sepsis from coagulase-negative Staphylococcus and three cases of accidental line extravasation. No other complications were reported. The success rate was 92.3%. CONCLUSION: Femoral venous catheterization using small diameter catheters in ELBW infants may be promising when other routes have been exhausted. Our results support that it is a feasible technique that can be performed at the bedside with successful results when conducted by experienced personnel.

Optimizing cell encapsulation condition in ECM-Collagen I hydrogels to support 3D neuronal cultures.

BACKGROUND: The emergence of three-dimensional (3D) cell culture in neural tissue engineering has significantly elevated the complexity and relevance of in vitro systems. This is due in large part to the incorporation of biomaterials to impart structural dimensionality on the neuronal cultures. However, a comprehensive understanding of how key seeding parameters affect changes in cell distribution and viability remain unreported. NEW METHOD: In this study, we systematically evaluated permutations in seeding conditions (i.e., cell concentration and atmospheric CO2 levels) to understand how these affect key parameters in 3D culture characterization (i.e., cell health and distribution). Primary rat cortical neurons (i.e., 2 × 106, 4 × 106, and 1 × 107 cells/mL) were entrapped in collagen blended with ECM proteins (ECM-Collagen) and exposed to atmospheric CO2 (i.e., 0 vs 5% CO2) during fibrillogenesis. RESULTS: At 14 days in vitro (DIV), cell distribution within the hydrogel was dependent on cell concentration and atmospheric CO2 during fibrillogenesis. A uniform distribution of cells was observed in cultures with 2 × 106 and 4 × 106 cells/mL in the presence of 5% CO2, while a heterogeneous distribution was observed in cultures with 1 × 107 cells/mL or in the absence of CO2. Furthermore, increased cell concentration was proportional to the rise in cell death at 14 DIV, although cells remain viable >30 DIV. COMPARISON WITH EXISTING METHODS: ECM-Collagen gels have been shown to increase cell viability of neurons long-term. CONCLUSION: In using ECM-collagen gels, we highlight the importance of optimizing seeding parameters and thorough 3D culture characterization to understand the neurophysiological responses of these 3D systems.

Thoracoscopic esophagoesophagostomy for a refractory stricture in a patient with esophageal atresia.

Anastomosis stricture is a well-known complication after esophageal atresia repair. Endoscopic dilatation is the gold standard treatment for esophageal stenosis. However, surgical interventions are indicated for refractory cases. We present a 2-year-old girl with esophageal stricture refractory to regular endoscopic dilatation after esophageal atresia repair that underwent thoracoscopic stricture resection and reanastomosis. Although thoracoscopic approach is widely used for esophageal atresia repair, this approach has not been used before for the treatment of anastomosis stricture.

A Reconfigurable In Vitro Model for Studying the Blood-Brain Barrier.

Much of what is currently known about the role of the blood-brain barrier (BBB) in regulating the passage of chemicals from the blood stream to the central nervous system (CNS) comes from animal in vivo models (requiring extrapolation to human relevance) and 2D static in vitro systems, which fail to capture the rich cell-cell and cell-matrix interactions of the dynamic 3D in vivo tissue microenvironment. In this work we have developed a BBB platform that allows for a high degree of customization in cellular composition, cellular orientation, and physiologically-relevant fluid dynamics. The system characterized and presented in this study reproduces key characteristics of a BBB model (e.g. tight junctions, efflux pumps) allowing for the formation of a selective and functional barrier. We demonstrate that our in vitro BBB is responsive to both biochemical and mechanical cues. This model further allows for culture of a CNS-like space around the BBB. The design of this platform is a valuable tool for studying BBB function as well as for screening of novel therapeutics.

Thoracoscopic recurrent tracheo-oesophageal fistula repair with mini endostapler: promising solution.

Recurrent tracheo-oesophageal fistula (TOF) is a common complication in children who underwent oesophageal atresia repair. The traditional surgical approach performed either by thoracotomy or cervicotomy is associated with a high rate of morbidity, mortality and new recurrence. In the last decades, endoscopic techniques have emerged as the minimally invasive alternative. However, it seems that the optimal treatment is still unknown. We present a patient with a recurrent TOF who underwent thoracoscopic closure using a 5.8 mm endostapler. The patient was extubated at the end of the procedure, and he started feeding the day after surgery. At 15 months of follow-up, he is asymptomatic. Thoracoscopic closure of TOF using endostaplers seems to be a safe alternative with some possible benefits compared with traditional and endoscopic approach.

Association between gallbladder agenesis and choledochal cyst: cause or coincidence?

This case report describes an extremely rare association between gallbladder agenesis and choledochal cyst (CC). A 9-year-old girl presented with recurrent abdominal pain in the right upper quadrant. Radiological studies revealed a CC type IVa and an agenesis of gallbladder and cystic duct. Due to the possibility of biliary neoplasm, the patient underwent cyst resection and hepaticoduodenostomy. Histopathological findings showed inflamed fibrous tissue covered by biliary epithelium with no evidence of malignancy.

Is the Laparoscopic Approach Safe for Inguinal Hernia Repair in Preterms?

Introduction: Although laparoscopic inguinal hernia repair in children has gained popularity in the last decades, this approach remains uncommon in preterm infants. The aim of this study was to compare the characteristics and the outcomes of indirect inguinal hernias in term and preterm infants. Material and Methods: From January 2002 to November 2015, all charts of the pediatric patients who underwent laparoscopic indirect inguinal hernia repair in one single institution within the first 6 months of life were revised. The data of 156 patients were analyzed retrospectively. Patients were divided in two groups: group I, including the preterm patients, and group II, including the term patients. Results: A total of 90 preterm infants and 66 term infants were included. In the group I, preoperative diagnosis was right-sided inguinal hernia in 20% of patients, left sided in 22.2%, and bilateral in 57.5%; while in the group II, preoperative diagnosis was right-sided inguinal hernia in 42.4% of infants, left sided in 15.2%, and bilateral in 42.4% (P = .01). In group I intraoperative diagnosis was right-sided inguinal hernia in 10% of patients, left sided in 16.7%, and bilateral in 73.3%; while in the group II, intraoperative diagnosis was right-sided inguinal hernia in 25.8% of infants, left sided in 12.1%, bilateral in 60.6%, and there was no hernia in one patient (P = .02). However, there was no statistically significant difference in the correct intraoperative diagnosis between both groups (P = .59). No statistical significance was observed between the two groups regarding postoperative complications. Conclusions: Bilateral inguinal hernia is more frequent in preterm infants compared to term infants, whereas the incidence of right-sided inguinal hernia is higher in term patients. Laparoscopic inguinal hernia repair in preterm infants seems to be safe and effective.

Inflammatory and Oxidative Stress Markers as Indicator of Atherogenesis in Rats: Antioxidants as Preventive Pharmacological Methods.

OBJECTIVE: The oxidative process in atherogenesis generated by proinflammatory induction and response to antioxidants vitamins in an experimental model were analyzed. METHODS: Male rats were used: (A)Control, (B)Control+vitamin E plus C, (C)Hyperfibrinogenemia and (D)Hyperfibrinogenemia+vitamins E plus C. Hyperfibrinogenemia induced by daily injection of adrenaline (0.1mg/day/rat) for 120 days. TREATMENT: 3.42 mg/kg of vitamin E plus 2.14 mg/kg of vitamin C, fifteen days after induction. Vascular histology analyzed by optical microscopy. Fibrinogen, nitrites and superoxide dismutase analyzed by spectrophotometry. STATISTICS: MANOVA, Hotelling test for post testing, significance level p<0.05. RESULTS: (C) group showed higher fibrinogen than (A) and (B)(p<0.001). Compared to (C) group, (D) showed a decrease of fibrinogen (p<0.001). A marked increase in nitrites was found in (C) versus (A), (B) and (D) groups (p<0.001). Superoxide dismutase activity increased in (C) group compared to groups (A) and (B) (p<0.001). In the group (D) an increase of the activity of this enzyme was observed in comparison to groups (C)(p<0.001), (A) and (B) (p<0.0001 in both). The (C) group shown endothelial denudation, thickening of the vascular intima and extracellular matrix enlargement with foam cells(p<0.001). CONCLUSION: These results strongly suggest that vitamins E plus C produce regression of inflammatory and oxidative stress processes in this experimental model.

Human Induced Pluripotent Stem Cell-Derived Endothelial Cells for Three-Dimensional Microphysiological Systems.

Microphysiological systems (MPS), or "organ-on-a-chip" platforms, aim to recapitulate in vivo physiology using small-scale in vitro tissue models of human physiology. While significant efforts have been made to create vascularized tissues, most reports utilize primary endothelial cells that hinder reproducibility. In this study, we report the use of human induced pluripotent stem cell-derived endothelial cells (iPS-ECs) in developing three-dimensional (3D) microvascular networks. We established a CDH5-mCherry reporter iPS cell line, which expresses the vascular endothelial (VE)-cadherin fused to mCherry. The iPS-ECs demonstrate physiological functions characteristic of primary endothelial cells in a series of in vitro assays, including permeability, response to shear stress, and the expression of endothelial markers (CD31, von Willibrand factor, and endothelial nitric oxide synthase). The iPS-ECs form stable, perfusable microvessels over the course of 14 days when cultured within 3D microfluidic devices. We also demonstrate that inhibition of TGF-ß signaling improves vascular network formation by the iPS-ECs. We conclude that iPS-ECs can be a source of endothelial cells in MPS providing opportunities for human disease modeling and improving the reproducibility of 3D vascular networks.

Erratum: WHO Grade IV Gliofibroma: A Grading Label Denoting Malignancy for an Otherwise Commonly Misinterpreted Neoplasm.

[This corrects the article on p. 325 in vol. 49, PMID: 26081826.].