In vitro models最新文献

Objective: Polycaprolactone (PCL) is a widely applied biomaterial in bone tissue engineering (BTE) due to its superior mechanical properties and biodegradability. However, the high hydrophobicity and low cell adhesion properties of PCL show limited cell interactions. Herein, we prepared the porous PCL/DBP composites with improved cell adhesion through the addition of demineralized bone powder (DBP). Three-dimensional scaffolds were fabricated by mixing various concentrations of DBP with PCL and applying non-solvent-induced phase separation (NIPS) and thermal-induced phase separation (TIPS) (N-TIPS) and solvent casting and particulate leaching (SCPL) to impart porosity.

Methods: A characteristic evaluation was performed through X-ray diffraction (XRD), morphological analysis, physicochemical analysis, bioactivity test, and mechanical test. Upon culture with mouse bone marrow stem cells (mBMSCs), proliferation and osteogenic differentiation of mBMSC were evaluated using quantitative dsDNA analysis and alkaline phosphatase (ALP) activity, respectively.

Results: The addition of DBP improved the physicochemical and mechanical properties of the scaffold and formed a large amount of hydroxyapatite (HAp). Also, cell proliferation and differentiation were increased by enhancing cell adhesion.

Conclusion: The porous PCL/DBP scaffolds could provide a favorable microenvironment for cell adhesion and be a promising biomaterial model for bone tissue engineering.

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The mechanical stimulation applied on engineered vascular constructs in perfusion bioreactors has been shown to be beneficial for their maturation. The level of mechanical stimulation applied on these constructs depends on the flow parameters of the circuit (e.g., fluid viscosity, flow rate, frequency, and pressure). As a group, these parameters are often overlooked in the literature, and they rarely meet the physiological values of the blood flow. For this reason, the level of circumferential stretching and shear stress that blood vessels experience in the human body are rarely reproduced. In this work, we reported the development of a physiologically relevant platform for (1) the in situ fabrication of vascular wall models based on collagen gel, and (2) their maturation under physiological levels of mechanical stimulation in a perfusion bioreactor (pulsatile flow rate of 100 mL/min, frequency of 1 Hz, pressure of 80-120 mmHg, and viscosity of 4 cP). One week of dynamic maturation oriented the seeded cells into the circumferential direction, increased the deposition of collagen and key elastin fiber-related proteins, and improved the mechanical properties in terms of tensile equilibrium elastic modulus (by 110%) and strength at break (by 63%) when compared to the static condition. In addition to the maturation study under selected physiologically relevant mechanical stimulation (such as adult, fetal, child, and hypertension conditions), the platform might also be used as a relevant in vitro testing system for new drugs or pro-active coating to medical devices (such as stents, endografts, and vascular prostheses) expected to trigger specific mechanisms or activities in vascular cells composing the arterial wall.

Stimulating brain tissue regeneration is a major challenge after central nervous system (CNS) injury, such as those observed from trauma or cerebrovascular accidents. Full regeneration is difficult even when a neurogenesis-associated repair response may occur. Currently, there are no effective treatments to stimulate brain tissue regeneration. However, biomaterial scaffolds are showing promising results, where hydrogels are the materials of choice to develop these supportive scaffolds for cell carriers. Their combination with growth factors, such as brain-derived neurotrophic factor (BDNF), basic fibroblast growth factor (bFGF), or vascular endothelial growth factor (VEGF), together with other cell therapy strategies allows the prevention of further neuronal death and can potentially lead to the direct stimulation of neurogenesis and vascularisation at the injured site. Imaging of the injured site is particularly critical to study the reestablishment of neural cell functionality after brain tissue injury. This review outlines the latest key advances associated with different strategies aiming to promote the neuroregeneration, imaging, and functional recovery of brain tissue.

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[This corrects the article DOI: 10.1007/s44164-022-00009-w.].

Balloon expandable coronary stenting has revolutionized the field of interventional cardiology as a potential, minimally invasive modality for treating coronary artery disease. Even though stenting is successful compared to angioplasty (that leaves no stent in place), still there are many associated clinical complications. Bare metal stents are associated with in-stent restenosis caused mostly by neointimal hyperplasia, whereas success of drug-eluting stents comes at the expense of late-stent thrombosis and neoatherosclerosis. Even though innovative and promising, clinical trials with bioabsorbable stents reported thrombosis and a rapid pace of degradation without performing scaffolding action in several instances. It should be noted that a vast majority of these stents are based on a metallic platform which still holds the potential to mitigate major cardiovascular events and reduced economic burden to patients, alongside continuous improvement in stent technology and antiplatelet regimes. Hence, a systematic review was conducted following PRISMA guidelines to assess the clinically relevant material properties for a metallic stent material. From a materials perspective, the major causes identified for clinical failure of stents are inferior mechanical properties and blood-material interaction-related complications at the stent surface. In addition to these, the stent material should possess increased radiopacity for improved visibility and lower magnetic susceptibility values for artefact reduction. Moreover, the review provides an overview of future scope of percutaneous coronary interventional strategy. Most importantly, this review highlights the need for an interdisciplinary approach by clinicians, biomaterial scientists, and interventional cardiologists to collaborate in mitigating the impediments associated with cardiovascular stents for alleviating sufferings of millions of people worldwide.

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Objective: Phenylketonuria (PKU) is caused by a specific mutation of the phenylalanine hydroxylase (PAH) gene. The deficiency of PAH results in high phenylalanine levels (Phe), low tyrosine levels (Tyr), and reduced catecholamine neurotransmitters. The majority of PKU patients, if untreated, develop severe mental retardation. The specific contribution of high Phe and low Tyr levels in mental retardation is largely unknown. In this study, we used organic hippocampal slice cultures in an optimized medium as an adequate culture model to decipher the precise role of high Phe and low Tyr levels on synaptic and glial integrity in PKU. The hippocampus is closely related to learning and memory and reduced catecholamine neurotransmitter levels can be neglected since these neurotransmitters do not derive from the hippocampus. Cultures exposed to physiological concentrations of Phe were compared with cultures exposed to doses of Phe/Tyr, as in the cerebral fluid of PKU patients.

Methods: Using capillary western blot analysis and immunohistochemistry, followed by quantitative image analysis, we tested the expression of various pre- and postsynaptic proteins (PSD95, synaptopodin, SNAP25, synaptophysin), glial cell markers (GFAP, Iba1, P2Y12, CD68, C3b), and the morphology of glial cells.

Results: We found a downregulation of the postsynaptic protein PSD95 and the presynaptic protein SNAP25 in the presence of high/low Phe/Tyr levels after 3 weeks, which, then however, recovered after 6 weeks in culture. Furthermore, no change in the expression pattern of glial proteins was observed.

Conclusion: Our results show that high Phe levels/low Tyr levels alone are unlikely to substantially contribute to mental retardation in PKU. The direct neurotoxic potency of high Phe/low Tyr concentrations is almost negligible since the effects are transient. The transient character in the presence of unchanged levels of high Phe/low Tyr points to a role of reduced catecholamine derivate neurotransmitters, rather than of high Phe/low Tyr levels in PKU.

Osteosarcoma (OS) is the most common primary bone cancer in children and young adults. This type of cancer is characterized by a high mortality rate, especially for patients with resistant lung metastases. Given its low incidence, high genetic heterogeneity, the lack of effective targets, and poor availability of relevant in vitro and in vivo models to study the tumor progression and the metastatic cascade, the pathophysiology of OS is still poorly understood and the translation of novel drugs into the market has become stagnant. Due to the importance of the tumor microenvironment (TME) in the development of metastases and the growing interest in targeting TME-specific pathways for novel therapeutics in cancer, models that closely represent these interactions are crucial for a better understanding of cancer-related events. In OS research, most studies rely on oversimplified two-dimensional (2D) assays and complex animal models that do not faithfully recapitulate OS development and progression. In turn, three-dimensional (3D) models are able to mimic not only the physical 3D environment in which cancer cells grow but also involve interactions with the TME, including its extracellular matrix, and thus are promising tools for drug screening studies. In this review, the existing and innovative OS in vitro 3D models are highlighted, focusing on how the TME is crucial to develop effective platforms for OS tumor and metastasis modeling in a physiologically relevant context.

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