Perfusable Tissue Bioprinted into a 3D-Printed Tailored Bioreactor System.

Bioprinting provides a powerful tool for regenerative medicine, as it allows tissue construction with a patient's specific geometry. However, tissue culture and maturation, commonly supported by dynamic bioreactors, are needed. We designed a workflow that creates an implant-specific bioreactor system, which is easily producible and customizable and supports cell cultivation and tissue maturation. First, a bioreactor was designed and different tissue geometries were simulated regarding shear stress and nutrient distribution to match cell culture requirements. These tissues were then directly bioprinted into the 3D-printed bioreactor. To prove the ability of cell maintenance, C2C12 cells in two bioinks were printed into the system and successfully cultured for two weeks. Next, human mesenchymal stem cells (hMSCs) were successfully differentiated toward an adipocyte lineage. As the last step of the presented strategy, we developed a prototype of an automated mobile docking station for the bioreactor. Overall, we present an open-source bioreactor system that is adaptable to a wound-specific geometry and allows cell culture and differentiation. This interdisciplinary roadmap is intended to close the gap between the lab and clinic and to integrate novel 3D-printing technologies for regenerative medicine.

Biomimetic Connection of Transcutaneous Implants with Skin.

Bacterial infection is a crucial complication in implant restoration, in particular in permanent skin-penetrating implants. Therein, the resulting gap between transcutaneous implant and skin represents a permanent infection risk, limiting the field of application and the duration of application. To overcome this limitation, a tight physiological connection is required to achieve a biological and mechanical welding for a long-term stable closure including self-healing probabilities. This study describes a new approach, wherein the implant is connected covalently to a highly porous electrospun fleece featuring physiological dermal integration potential. The integrative potential of the scaffold is shown in vitro and confirmed in vivo, further demonstrating tissue integration by neovascularization, extracellular matrix formation, and prevention of encapsulation. To achieve a covalent connection between fleece and implant surface, self-initiated photografting and photopolymerization of hydroxyethylmethacrylate is combined with a new crosslinker (methacrylic acid coordinated titanium-oxo clusters) on proton-abstractable implant surfaces. For implant modification, the attached fleece is directed perpendicular from the implant surface into the surrounding dermal tissue. First in vitro skin implantations demonstrate the implants' dermal integration capability as well as wound closure potential on top of the fleece by epithelialization, establishing a bacteria-proof and self-healing connection of skin and transcutaneous implant.

Translation of biophysical environment in bone into dynamic cell culture under flow for bone tissue engineering.

Bone is a dynamic environment where osteocytes, osteoblasts, and mesenchymal stem/progenitor cells perceive mechanical cues and regulate bone metabolism accordingly. In particular, interstitial fluid flow in bone and bone marrow serves as a primary biophysical stimulus, which regulates the growth and fate of the cellular components of bone. The processes of mechano-sensory and -transduction towards bone formation have been well studied mainly in vivo as well as in two-dimensional (2D) dynamic cell culture platforms, which elucidated mechanically induced osteogenesis starting with anabolic responses, such as production of nitrogen oxide and prostaglandins followed by the activation of canonical Wnt signaling, upon mechanosensation. The knowledge has been now translated into regenerative medicine, particularly into the field of bone tissue engineering, where multipotent stem cells are combined with three-dimensional (3D) scaffolding biomaterials to produce transplantable constructs for bone regeneration. In the presence of 3D scaffolds, the importance of suitable dynamic cell culture platforms increases further not only to improve mass transfer inside the scaffolds but to provide appropriate biophysical cues to guide cell fate. In principle, the concept of dynamic cell culture platforms is rooted to bone mechanobiology. Therefore, this review primarily focuses on biophysical environment in bone and its translation into dynamic cell culture platforms commonly used for 2D and 3D cell expansion, including their advancement, challenges, and future perspectives. Additionally, it provides the literature review of recent empirical studies using 2D and 3D flow-based dynamic cell culture systems for bone tissue engineering.

Establishing and testing a robot-based platform to enable the automated production of nanoparticles in a flexible and modular way.

Robotic systems facilitate relatively simple human-robot interaction for non-robot experts, providing the flexibility to implement different processes. In this context, shorter process times, as well as an increased product and process quality could be achieved. Robots short time-consuming processes, take over ergonomically unfavorable tasks and work efficiently all the time. In addition, flexible production is possible while maintaining or even increasing safety. This study describes the successful development of a dual-arm robot-based modular infrastructure and the establishment of an automated process for the reproducible production of nanoparticles. As proof of concept, a manual synthesis protocol for silica nanoparticle preparation with a diameter of about 200 nm as building blocks for photonic crystals was translated into a fully automated process. All devices and components of the automated system were optimized and adapted according to the synthesis requirements. To demonstrate the benefit of the automated nanoparticle production, manual (synthesis done by lab technicians) and automated syntheses were benchmarked. To this end, different processing parameters (time of synthesis procedure, accuracy of dosage etc.) and the properties of the produced nanoparticles were compared. We demonstrate that the use of the robot not only increased the synthesis accuracy and reproducibility but reduced the personnel time and costs up to 75%.

Unique osteogenic profile of bone marrow stem cells stimulated in perfusion bioreactor is Rho-ROCK-mediated contractility dependent.

The fate determination of bone marrow mesenchymal stem/stromal cells (BMSC) is tightly regulated by mechanical cues, including fluid shear stress. Knowledge of mechanobiology in 2D culture has allowed researchers in bone tissue engineering to develop 3D dynamic culture systems with the potential for clinical translation in which the fate and growth of BMSC are mechanically controlled. However, due to the complexity of 3D dynamic cell culture compared to the 2D counterpart, the mechanisms of cell regulation in the dynamic environment remain relatively undescribed. In the present study, we analyzed the cytoskeletal modulation and osteogenic profiles of BMSC under fluid stimuli in a 3D culture condition using a perfusion bioreactor. BMSC subjected to fluid shear stress (mean 1.56 mPa) showed increased actomyosin contractility, accompanied by the upregulation of mechanoreceptors, focal adhesions, and Rho GTPase-mediated signaling molecules. Osteogenic gene expression profiling revealed that fluid shear stress promoted the expression of osteogenic markers differently from chemically induced osteogenesis. Osteogenic marker mRNA expression, type 1 collagen formation, ALP activity, and mineralization were promoted in the dynamic condition, even in the absence of chemical supplementation. The inhibition of cell contractility under flow by Rhosin chloride, Y27632, MLCK inhibitor peptide-18, or Blebbistatin revealed that actomyosin contractility was required for maintaining the proliferative status and mechanically induced osteogenic differentiation in the dynamic culture. The study highlights the cytoskeletal response and unique osteogenic profile of BMSC in this type of dynamic cell culture, stepping toward the clinical translation of mechanically stimulated BMCS for bone regeneration.

Non-destructive classification of unlabeled cells: Combining an automated benchtop magnetic resonance scanner and artificial intelligence.

In order to treat degenerative diseases, the importance of advanced therapy medicinal products has increased in recent years. The newly developed treatment strategies require a rethinking of the appropriate analytical methods. Current standards are missing the complete and sterile analysis of the product of interest to make the drug manufacturing effort worthwhile. They only consider partial areas of the sample or product while also irreversibly damaging the investigated specimen. Two-dimensional T1 / T2 MR relaxometry meets these requirements and is therefore a promising in-process control during the manufacturing and classification process of cell-based treatments. In this study a tabletop MR scanner was used to perform two-dimensional MR relaxometry. Throughput was increased by developing an automation platform based on a low-cost robotic arm, resulting in the acquisition of a large dataset of cell-based measurements. Two-dimensional inverse Laplace transformation was used for post-processing, followed by data classification performed with support vector machines (SVM) as well as optimized artificial neural networks (ANN). The trained networks were able to distinguish non-differentiated from differentiated MSCs with a prediction accuracy of 85%. To increase versatility, an ANN was trained on 354 independent, biological replicates distributed across ten different cell lines, resulting in a prediction accuracy of up to 98% depending on data composition. The present study provides a proof of principle for the application of T1 / T2 relaxometry as a non-destructive cell classification method. It does not require labeling of cells and can perform whole mount analysis of each sample. Since all measurements can be performed under sterile conditions, it can be used as an in-process control for cellular differentiation. This distinguishes it from other characterization techniques, as most are destructive or require some type of cell labeling. These advantages highlight the technique's potential for preclinical screening of patient-specific cell-based transplants and drugs.

Healthberry 865® and a Subset of Its Single Anthocyanins Attenuate Oxidative Stress in Human Endothelial In Vitro Models.

Oxidative stress and inflammation play a pivotal role in the development of cardiovascular diseases, an ever-growing worldwide problem. As a non-pharmacological approach, diet, especially a flavonoid-rich diet, showed promising results in the reduction of cardiovascular diseases and alleviation of their symptoms. In this study, in vitro systems based on human microvascular endothelial cells (hmvEC) and human umbilical cord endothelial cells (HUVEC) were established to determine the effect of Healthberry 865® (HB) and ten of its relating single anthocyanins on oxidative stress. Furthermore, five metabolites were used in order to examine the effect of anthocyanin's most common breakdown molecules. The results showed an effect of HB in both models after 24 h, as well as most of its single anthocyanins. Cyanidin-rutinoside, peonidin-galactoside, and petunidin-glucoside had a model-specific effect. For the metabolites, phloroglucinaldeyhde (PGA) showed an effect in both models, while vanillic acid (VA) only had an effect in HUVEC. When combined, a combination of several anthocyanins did not have a cumulative effect, except for combining glucosides in hmvEC. The combination of PGA and VA even revealed an inhibitive behavior. Overall, the study demonstrates the antioxidative effect of HB and several of its single anthocyanins and metabolites, which are partially model specific, and coincides with animal studies.

Decellularization of Full Heart-Optimizing the Classical Sodium-Dodecyl-Sulfate-Based Decellularization Protocol.

Compared to cell therapy, where cells are injected into a defect region, the treatment of heart infarction with cells seeded in a vascularized scaffold bears advantages, such as an immediate nutrient supply or a controllable and persistent localization of cells. For this purpose, decellularized native tissues are a preferable choice as they provide an in vivo-like microenvironment. However, the quality of such scaffolds strongly depends on the decellularization process. Therefore, two protocols based on sodium dodecyl sulfate or sodium deoxycholate were tailored and optimized for the decellularization of a porcine heart. The obtained scaffolds were tested for their applicability to generate vascularized cardiac patches. Decellularization with sodium dodecyl sulfate was found to be more suitable and resulted in scaffolds with a low amount of DNA, a highly preserved extracellular matrix composition, and structure shown by GAG quantification and immunohistochemistry. After seeding human endothelial cells into the vasculature, a coagulation assay demonstrated the functionality of the endothelial cells to minimize the clotting of blood. Human-induced pluripotent-stem-cell-derived cardiomyocytes in co-culture with fibroblasts and mesenchymal stem cells transferred the scaffold into a vascularized cardiac patch spontaneously contracting with a frequency of 25.61 ± 5.99 beats/min for over 16 weeks. The customized decellularization protocol based on sodium dodecyl sulfate renders a step towards a preclinical evaluation of the scaffolds.

Optimization and Validation of a Custom-Designed Perfusion Bioreactor for Bone Tissue Engineering: Flow Assessment and Optimal Culture Environmental Conditions.

Various perfusion bioreactor systems have been designed to improve cell culture with three-dimensional porous scaffolds, and there is some evidence that fluid force improves the osteogenic commitment of the progenitors. However, because of the unique design concept and operational configuration of each study, the experimental setups of perfusion bioreactor systems are not always compatible with other systems. To reconcile results from different systems, the thorough optimization and validation of experimental configuration are required in each system. In this study, optimal experimental conditions for a perfusion bioreactor were explored in three steps. First, an in silico modeling was performed using a scaffold geometry obtained by microCT and an expedient geometry parameterized with porosity and permeability to assess the accuracy of calculated fluid shear stress and computational time. Then, environmental factors for cell culture were optimized, including the volume of the medium, bubble suppression, and medium evaporation. Further, by combining the findings, it was possible to determine the optimal flow rate at which cell growth was supported while osteogenic differentiation was triggered. Here, we demonstrated that fluid shear stress up to 15 mPa was sufficient to induce osteogenesis, but cell growth was severely impacted by the volume of perfused medium, the presence of air bubbles, and medium evaporation, all of which are common concerns in perfusion bioreactor systems. This study emphasizes the necessity of optimization of experimental variables, which may often be underreported or overlooked, and indicates steps which can be taken to address issues common to perfusion bioreactors for bone tissue engineering.

Evaluation of a clinical decision support tool to predict permanence of retrievable inferior vena cava filters.

OBJECTIVE: To evaluate the usefulness of a published clinical decision support tool to predict the likelihood of a retrievable inferior vena cava (IVC) filter being maintained as a permanent device. METHODS: This multicenter retrospective cohort study included 1498 consecutive patients (852 men and 646 women; median age, 60 years; range, 18-98 years) who underwent retrievable IVC filter insertion between January 2012 and December 2019. The indications for IVC filtration, baseline neurologic disease, history of venous thromboembolism (VTE), and underlying malignancy were recorded. Accuracy, sensitivity, and specificity of a published clinical support tool were calculated to determine the usefulness of the tool. RESULTS: The majority of filters (1271/1498 [85%]) were placed for VTE with a contraindication to anticoagulation. A history of VTE was present in 811 of 1498 patients (54%) patients; underlying malignancy in 531 of 1498 patients (35%), and neurological disease in 258 of 1498 patients (17%). Of the 1498 filters, 456 (30%) were retrieved, 276 (18%) were maintained as permanent devices on follow-up, and 766 (51%) filters were not retrieved. The accuracy of the clinical prediction model was 61%, sensitivity was 60%, and specificity was 62%. CONCLUSIONS: A previously published clinical decision support tool to predict permanence of IVC filters had modest usefulness in the examined population; this factor should be taken into account when using this clinical decision support tool outside of the original study population. Future studies are required to refine the predictive capability of IVC filter decision support tools for broader use across different patient populations.

Safety and Effectiveness of Advanced Retrieval Techniques for Inferior Vena Cava Filters Compared with Standard Retrieval Techniques: A Systematic Review of the Literature and Meta-Analysis.

PURPOSE: To investigate the pooled safety and effectiveness of advanced retrieval techniques for inferior vena cava (IVC) filters compared with standard retrieval techniques through a systematic review of the literature and meta-analysis. MATERIALS AND METHODS: A systematic search of retrievable IVC filters between 1980 and 2020 was conducted. Studies were included if both standard and advanced retrieval techniques were utilized in the same cohort, retrieval success rates and adverse event rates were described for each technique, and advanced techniques were employed after the failure of standard techniques. Study heterogeneity was assessed by the I2 statistic. The outcomes included retrieval success rates and adverse event rates for standard and advanced retrieval techniques. RESULTS: Of 1,631 articles, 21 (1%) studies met inclusion criteria. The study heterogeneity was high with an I2 of 98%. The pooled random-effects outcomes included an overall standard retrieval success rate of 76% (95% confidence interval [CI], 65%-84%), with minor and major adverse event rates of 1% (95% CI, 0%-1%) and 1% (95% CI, 0%-1%), respectively. The overall pooled advanced retrieval success rates were 90% (95% CI, 82%-94%), with minor and major adverse event rates of 5% (95% CI, 2%-9%) and 4% (95% CI, 2%-6%), respectively. The standard retrievals were 16% less likely (risk ratio) to be successful (95% CI, 32% less likely to 4% more likely; P = .11). The major and minor adverse event rates were 88% and 84% less likely in standard retrievals compared with advanced retrievals, respectively (95% CI, 86%-94%; P < .0001; 95% CI, 70%-91%; P < .0001). CONCLUSIONS: Advanced retrieval techniques for IVC filters permit a higher retrieval success rate with low adverse event rates in cases of standard retrieval failure.

Online Measurement System for Dynamic Flow Bioreactors to Study Barrier Integrity of hiPSC-Based Blood-Brain Barrier In Vitro Models.

Electrochemical impedance spectroscopy (EIS) is a noninvasive, reliable, and efficient method to analyze the barrier integrity of in vitro tissue models. This well-established tool is used most widely to quantify the transendothelial/epithelial resistance (TEER) of Transwell-based models cultured under static conditions. However, dynamic culture in bioreactors can achieve advanced cell culture conditions that mimic a more tissue-specific environment and stimulation. This requires the development of culture systems that also allow for the assessment of barrier integrity under dynamic conditions. Here, we present a bioreactor system that is capable of the automated, continuous, and non-invasive online monitoring of cellular barrier integrity during dynamic culture. Polydimethylsiloxane (PDMS) casting and 3D printing were used for the fabrication of the bioreactors. Additionally, attachable electrodes based on titanium nitride (TiN)-coated steel tubes were developed to perform EIS measurements. In order to test the monitored bioreactor system, blood-brain barrier (BBB) in vitro models derived from human-induced pluripotent stem cells (hiPSC) were cultured for up to 7 days. We applied equivalent electrical circuit fitting to quantify the electrical parameters of the cell layer and observed that TEER gradually decreased over time from 2513 Ω·cm2 to 285 Ω·cm2, as also specified in the static control culture. Our versatile system offers the possibility to be used for various dynamic tissue cultures that require a non-invasive monitoring system for barrier integrity.

Toward allogenizing a xenograft: Xenogeneic cardiac scaffolds recellularized with human-induced pluripotent stem cells do not activate human naïve neutrophils.

The limited availability of human donor organs suitable for transplantation has resulted in ever-increasing patient waiting lists globally. Xenotransplantation is considered a potential option, but is yet to reach clinical practice. Although remarkable progress has been made in overcoming immunological rejection, issues with functionality are still to be resolved. Bioengineering approaches have been used to create cardiac tissues with optimized functions. The use of decellularized xenogeneic cardiac tissues seeded with donor-derived cardiac cells may prove to be a viable strategy as supporting structures of the native tissue such as vasculature can be utilized. Here we used sequential perfusion to decellularize adult rat hearts. The acellular scaffolds were reseeded with human endothelial cells, human fibroblasts, human mesenchymal stem cells, and cardiac cells derived from human-induced pluripotent stem cells. The ability of the resultant recellularized rat scaffolds to activate human naïve neutrophils in vitro was investigated to measure xenogeneic recognition. Our results demonstrate that in contrast to cadaveric xenogeneic hearts, acellular and recellularized xenogeneic scaffolds did not activate human naïve neutrophils and suggest that decellularization removes the xenogeneic antigens that lead to human naïve neutrophil activation thus allowing human cells to populate the now "allogenized" xenogeneic scaffolds.

Fully Synthetic 3D Fibrous Scaffolds for Stromal Tissues-Replacement of Animal-Derived Scaffold Materials Demonstrated by Multilayered Skin.

The extracellular matrix (ECM) of soft tissues in vivo has remarkable biological and structural properties. Thereby, the ECM provides mechanical stability while it still can be rearranged via cellular remodeling during tissue maturation or healing processes. However, modern synthetic alternatives fail to provide these key features among basic properties. Synthetic matrices are usually completely degraded or are inert regarding cellular remodeling. Based on a refined electrospinning process, a method is developed to generate synthetic scaffolds with highly porous fibrous structures and enhanced fiber-to-fiber distances. Since this approach allows for cell migration, matrix remodeling, and ECM synthesis, the scaffold provides an ideal platform for the generation of soft tissue equivalents. Using this matrix, an electrospun-based multilayered skin equivalent composed of a stratified epidermis, a dermal compartment, and a subcutis is able to be generated without the use of animal matrix components. The extension of classical dense electrospun scaffolds with high porosities and motile fibers generates a fully synthetic and defined alternative to collagen-gel-based tissue models and is a promising system for the construction of tissue equivalents as in vitro models or in vivo implants.

A Review of the Properties of Anthocyanins and Their Influence on Factors Affecting Cardiometabolic and Cognitive Health.

The incidence of cardiovascular and metabolic diseases has increased over the last decades and is an important cause of death worldwide. An upcoming ingredient on the nutraceutical market are anthocyanins, a flavonoid subgroup, abundant mostly in berries and fruits. Epidemiological studies have suggested an association between anthocyanin intake and improved cardiovascular risk, type 2 diabetes and myocardial infarct. Clinical studies using anthocyanins have shown a significant decrease in inflammation markers and oxidative stress, a beneficial effect on vascular function and hyperlipidemia by decreasing low-density lipoprotein and increasing high-density lipoprotein. They have also shown a potential effect on glucose homeostasis and cognitive decline. This review summarizes the effects of anthocyanins in in-vitro, animal and human studies to give an overview of their application in medical prevention or as a dietary supplement.

Modeling of the Human Bone Environment: Mechanical Stimuli Guide Mesenchymal Stem Cell-Extracellular Matrix Interactions.

In bone tissue engineering, the design of in vitro models able to recreate both the chemical composition, the structural architecture, and the overall mechanical environment of the native tissue is still often neglected. In this study, we apply a bioreactor system where human bone-marrow hMSCs are seeded in human femoral head-derived decellularized bone scaffolds and subjected to dynamic culture, i.e., shear stress induced by continuous cell culture medium perfusion at 1.7 mL/min flow rate and compressive stress by 10% uniaxial load at 1 Hz for 1 h per day. In silico modeling revealed that continuous medium flow generates a mean shear stress of 8.5 mPa sensed by hMSCs seeded on 3D bone scaffolds. Experimentally, both dynamic conditions improved cell repopulation within the scaffold and boosted ECM production compared with static controls. Early response of hMSCs to mechanical stimuli comprises evident cell shape changes and stronger integrin-mediated adhesion to the matrix. Stress-induced Col6 and SPP1 gene expression suggests an early hMSC commitment towards osteogenic lineage independent of Runx2 signaling. This study provides a foundation for exploring the early effects of external mechanical stimuli on hMSC behavior in a biologically meaningful in vitro environment, opening new opportunities to study bone development, remodeling, and pathologies.