Project description:The isolation and culture of neonatal murine cardiac cells are valuable techniques for studying their properties and molecular mechanisms in response to various treatments or conditions. Here, we present a protocol for isolating a high yield of viable neonatal murine cardiac cells, including functional, beating cardiomyocytes. We describe the steps of heart extraction, washing and pre-digestion, digestion, and cell seeding. We detail procedures for mechanical and enzymatic digestions, conducted in a controlled environment within a cell culture incubator. For complete details on the use and execution of this protocol, please refer to Bongiovanni et al.1.
Project description:ObjectiveTo study the effect of co-culturing chondrocytes with osteoblasts on hypoxia-inducible factor (HIF)-1 pathway of chondrocytes and its mechanism.MethodsChondrocytes and osteoblasts were separately extracted from the knee joint and skull of newborn mice by trypsin digestion. The co-culturing system of osteoblasts and chondrocytes was constructed by using Transwell inserts to culture the osteoblasts and 6-well plate to culture the chondrocytes. We used qRT-PCR to examine changes in the mRNA expression of HIFs and its target gene pyruvate dehydrogenase kinase 1 ( PDK1) in chondrocytes co-cultured for 24 h. Western blot was used to analyze changes in the protein expression of HIFs and PDK1 and the changes in the activation of mitogen activated protein kinase (MAPK) signaling pathway after the cells were co-cultured for 48 h. Reactive oxygen species (ROS) staining was done to show the changes of ROS production in chondrocytes co-cultured for 48 h.ResultsThe results of qRT-PCR and Western blot showed upregulated levels of HIF-1α gene and protein expression ( P<0.05) in the chondrocytes after they were co-cultured with osteoblasts. The gene and protein expression levels of PDK1 , the target gene of HIF-1, were also upregulated ( P<0.05). ROS staining showed that co-culturing of chondrocytes with osteoblasts decreased ROS production in chondrocytes. Western blot revealed that extracellular signal-regulated kinase (ERK) 1/2 and p38 signaling of co-cultured chondrocytes were enhanced ( P<0.05).ConclusionCo-culturing with osteoblasts enhanced the ERK1/2 and p38 signaling of chondrocytes and upregulated the HIF-1 pathway of chondrocytes.
Project description:Collagenase products are crucial to isolate primary cells in basic research and clinical therapies, where their stability in collagenolytic activity is required. However, currently standard collagenase products from Clostridium histolyticum lack such stability. Previously, we produced a recombinant 74-kDa collagenase from Grimontia hollisae, which spontaneously became truncated to ~60 kDa and possessed no stability. In this study, to generate G. hollisae collagenase useful as a collagenase product, we designed recombinant 62-kDa collagenase consisting only of the catalytic domain, which exhibits high production efficiency. We demonstrated that this recombinant collagenase is stable and active under physiological conditions. Moreover, it possesses higher specific activity against collagen and cleaves a wider variety of collagens than a standard collagenase product from C. histolyticum. Furthermore, it dissociated murine pancreata by digesting the collagens within the pancreata in a dose-dependent manner, and this dissociation facilitated isolation of pancreatic islets with masses and numbers comparable to those isolated using the standard collagenase from C. histolyticum. Implantation of these isolated islets into five diabetic mice led to normalisation of the blood glucose concentrations of all the recipients. These findings suggest that recombinant 62-kDa collagenase from G. hollisae can be used as a collagenase product to isolate primary cells.
Project description:Cartilage and chondrocytes experience loading that causes alterations in chondrocyte biological activity. In vivo chondrocytes are surrounded by a pericellular matrix with a stiffness of ~25-200kPa. Understanding the mechanical loading environment of the chondrocyte is of substantial interest for understanding chondrocyte mechanotransduction. The first objective of this study was to analyze the spatial variability of applied mechanical deformations in physiologically stiff agarose on cellular and sub-cellular length scales. Fluorescent microspheres were embedded in physiologically stiff agarose hydrogels. Microsphere positions were measured via confocal microscopy and used to calculate displacement and strain fields as a function of spatial position. The second objective was to assess the feasibility of encapsulating primary human chondrocytes in physiologically stiff agarose. The third objective was to determine if primary human chondrocytes could deform in high-stiffness agarose gels. Primary human chondrocyte viability was assessed using live-dead imaging following 24 and 72h in tissue culture. Chondrocyte shape was measured before and after application of 10% compression. These data indicate that (1) displacement and strain precision are ~1% and 6.5% respectively, (2) high-stiffness agarose gels can maintain primary human chondrocyte viability of >95%, and (3) compression of chondrocytes in 4.5% agarose can induce shape changes indicative of cellular compression. Overall, these results demonstrate the feasibility of using high-concentration agarose for applying in vitro compression to chondrocytes as a model for understanding how chondrocytes respond to in vivo loading.
Project description:PURPOSE: To describe a new method of culturing mouse corneal epithelial cells (MCECs). METHODS: MCECs were isolated from C57/BL6 mouse corneas and cultured on type-I collagen-coated plastic dishes in low-calcium progenitor cell targeting medium (CnT-50). Expression of the mRNAs of N-terminal truncated isoform of p63 (DNp63), cytokeratin 12 (K12), and cytokeratin 14 (K14) were determined by reverse transcription-polymerase chain reaction (RT-PCR). To examine the differentiation capabilities, passage 3 (P3) MCECs at confluence were subcultured on amniotic membrane (AM) in a differentiation medium (CnT-30) until confluence. At confluence, 1 mM calcium was added and cultured for 4 more days. The expression of K12 in the stratified MCECs was analyzed by immunostaining. RESULTS: The MCECs cultured in CnT-50 proliferated until at least P10. The number of cells at confluency at P3 was 61.8 (SD +/-9.4, n=5) times that at P0. MCECs cultured on AM in CnT-30 with addition of calcium were stratified up to two to three layers, and the stratified MCECs expressed K12. DNp63 mRNA was continuously expressed throughout the different passages, and K12 mRNA was detected in P0 cells and the stratified MCECs on AM. CONCLUSIONS: Cultured MCECs maintain their proliferation and differentiation capabilities as well as their corneal epithelial cell characteristics. These results suggest that MCECs produced by this culturing method provide a useful experimental model which can enable further development of research of the corneal epithelium.
Project description:In natural visual environments, we use attention to select between relevant and irrelevant stimuli that are presented simultaneously. Our attention to objects in our visual field is largely controlled endogenously, but is also affected exogenously through the influence of novel stimuli and events. The study of endogenous and exogenous attention as separate mechanisms has been possible in behavioral and functional imaging studies, where multiple stimuli can be presented continuously and simultaneously. It has also been possible in electroencephalogram studies using the steady-state visual-evoked potential (SSVEP); however, it has not been possible in conventional event-related potential (ERP) studies, which are hampered by the need to present suddenly onsetting stimuli in isolation. This is unfortunate as the ERP technique allows for the analysis of human physiology with much greater temporal resolution than functional magnetic resonance imaging or the SSVEP. While ERP studies of endogenous attention have been widely reported, these experiments have a serious limitation in that the suddenly onsetting stimuli, used to elicit the ERP, inevitably have an exogenous, attention-grabbing effect. Recently we have shown that it is possible to derive separate event-related responses to concurrent, continuously presented stimuli using the VESPA (visual-evoked spread spectrum analysis) technique. In this study we employed an experimental paradigm based on this method, in which two pairs of diagonally opposite, non-contiguous disc-segment stimuli were presented, one pair to be ignored and the other to be attended. VESPA responses derived for each pair showed a strong modulation at 90-100 ms (during the visual P1 component), demonstrating the utility of the method for isolating endogenous visuo-spatial attention effects.
Project description:Percutaneous coronary intervention in patients with dextrocardia presents several challenges due to abnormal location of the heart, mirror image pattern of aortic arch and its branches, and abnormal coronary origin and orientation. The challenges involve appropriate choice of vascular access, guiding catheters, engagement technique, acquisition and interpretation of radiological orientation of coronary anatomy, and appropriate radiological angles and views. We report a patient with dextrocardia and situs inversus who presented with acute ST segment elevation myocardial infarction and was successfully treated with trans-radial primary percutaneous coronary intervention using "double inversion technique." We also emphasize that left radial artery approach may be technically preferred to right radial artery approach due to mirror image aortic arch branching pattern. <Learning objective: 1. Percutaneous coronary intervention in patients with dextrocardia presents several challenges due to abnormal location of the heart, mirror image pattern of aortic arch and its branches, and abnormal coronary origin and orientation. 2. These challenges can be overcome by "double inversion technique," which allows the operator to interpret coronary anatomy and perform intervention as in levocardia.>.
Project description:The cranial base contains a special type of growth plate termed the synchondrosis, which functions as the growth center of the skull. The synchondrosis is composed of bidirectional opposite-facing layers of resting, proliferating, and hypertrophic chondrocytes, and lacks the secondary ossification center. In long bones, the resting zone of the epiphyseal growth plate houses a population of parathyroid hormone-related protein (PTHrP)-expressing chondrocytes that contribute to the formation of columnar chondrocytes. Whether PTHrP+ chondrocytes in the synchondrosis possess similar functions remains undefined. Using Pthrp-mCherry knock-in mice, we found that PTHrP+ chondrocytes predominantly occupied the lateral wedge-shaped area of the synchondrosis, unlike those in the femoral growth plate that reside in the resting zone within the epiphysis. In vivo cell-lineage analyses using a tamoxifen-inducible Pthrp-creER line revealed that PTHrP+ chondrocytes failed to establish columnar chondrocytes in the synchondrosis. Therefore, PTHrP+ chondrocytes in the synchondrosis do not possess column-forming capabilities, unlike those in the resting zone of the long bone growth plate. These findings support the importance of the secondary ossification center within the long bone epiphysis in establishing the stem cell niche for PTHrP+ chondrocytes, the absence of which may explain the lack of column-forming capabilities of PTHrP+ chondrocytes in the cranial base synchondrosis.
Project description:Cartilage tissue equivalents formed from hydrogels containing chondrocytes could provide a solution for replacing damaged cartilage. Previous approaches have often utilized elastic hydrogels. However, elastic stresses may restrict cartilage matrix formation and alter the chondrocyte phenotype. Here we investigated the use of viscoelastic hydrogels, in which stresses are relaxed over time and which exhibit creep, for three-dimensional (3D) culture of chondrocytes. We found that faster relaxation promoted a striking increase in the volume of interconnected cartilage matrix formed by chondrocytes. In slower relaxing gels, restriction of cell volume expansion by elastic stresses led to increased secretion of IL-1β, which in turn drove strong up-regulation of genes associated with cartilage degradation and cell death. As no cell-adhesion ligands are presented by the hydrogels, these results reveal cell sensing of cell volume confinement as an adhesion-independent mechanism of mechanotransduction in 3D culture, and highlight stress relaxation as a key design parameter for cartilage tissue engineering.
Project description:Primary neurons from rodent brain hippocampus and cortex have served as important tools in biomedical research over the years. However, protocols for the preparation of primary neurons vary, which often lead to conflicting results. This report provides a robust and reliable protocol for the production of primary neuronal cultures from the cortex and hippocampus with minimal contribution of non-neuronal cells. The neurons were grown in serum-free media and maintained for several weeks without any additional feeder cells. The neuronal cultures maintained according to this protocol differentiate and by 3 weeks develop extensive axonal and dendritic branching. The cultures produced by this method show excellent reproducibility and can be used for histological, molecular and biochemical methods.