Project description:Mass spectrometry imaging (MSI) can analyze the spatial distribution of hundreds of different molecules directly from tis-sue sections usually placed on conductive glass slides to provide conductivity on the sample surface. Additional experiments are often required for molecular identification using consecutive sections on membrane slides compatible with laser capture microdissection (LMD). In this work, we demonstrate for the first time the use of a single conductive slide for both matrix assisted laser desorption ionization (MALDI)-MSI and direct proteomics. In this workflow, regions of interest can be directly ablated with LMD while preserving protein integrity. These results offer an alternative for MSI based multimodal spatial-omics.
Project description:Despite efforts to mature human pluripotent stem cell-derived cardiomyocytes (hPSC-CMs) for disease modeling and high throughput screening, cells remain immature and may not reflect adult biology. Recent advancements utilize electro-mechanical and paracrine stimulation to functionally mature cardiomyocytes, but the resulting engineered constructs continue to lack a microenvironment conducive to electrical signal propagation and maturity. Conductive polymers are attractive candidates to facilitate electrical communication between gaps in sparse hPSC-CM clusters or between hPSC-CMs to repair conduction defects. To create a conductive polymer platform for improved electrical signal propagation between hPSC-CMs and achieve electrical maturity, we electrospun poly(3,4-ethylendioxythiophene):polystyrene sulfonate (PEDOT:PSS) blended with 8% (w/v) poly(vinyl alcohol) (PVA). Matrix fiber structure remained stable over 4 weeks in buffer, stiffness remains near cardiac stiffness in vivo, and electrical conductivity scaled with PEDOT:PSS concentration. When fibroblasts were added to fibers, cells had higher initial attachment to PEDOT:PSS compared to PVA-only scaffolds, and after 5 days, over 90% of fibroblasts remained viable on PEDOT:PSS scaffolds compared to PVA-only scaffolds. Electrically excitable hPSC-CMs cultured on conductive substrates exhibited an upregulation of cardiac and muscle-related genes as opposed to non-conductive substrates. These cells further displayed increased desmoplakin (DP) localization on conductive scaffolds, indicating an improvement in the mechanical stability of our hPSC-CMs. Sarcomere organization also scaled with increasing PEDOT:PSS concentration, even in sub-monolayer cell densities, suggesting that improved organization of the contractile machinery in these cells was due to the electrical condition of the matrix. Calcium handling indicated higher calcium flux with a shorter time to peak, further suggesting improved electrical maturity, even when sub-confluent. Taken together, these data suggest that PEDOT:PSS/PVA scaffolds are stable, of a stiffness relevant to cardiomyocytes, and supportive of electrical coupling even in the absence of a monolayer, which may improve cardiac disease modeling and drug development.
Project description:Biomaterial-based bone tissue engineering offers a promising prospect for the treatment of bone defects. In particular, the ability of biomaterials to regulate the immune microenvironment of the defect site is essential for effective bone regeneration. Electro-biomaterials have been confirmed to induce macrophage M2 polarization through metabolic pathways, thereby enhancing bone regeneration. Considering the central role of mitochondria in cellular metabolism and their ability to influence the function of neighboring cells through intercellular transfer, and inspired by the fact that tumor cells can uptake mitochondria from immune cells to generate energy, we hypothesize that the metabolic activation of immune cells by electro-materials can be transmitted to preosteoblasts through mitochondria to promote bone repair. Therefore, this study proposed a conductive micro-hydrogel (CMH) system composed of conductive hydrogel microspheres made from GelMA and poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS), which served as scaffolds for defect filling, and a biomimetic periosteum made from poly-l-lactic acid (PLLA) and polydopamine (PDA) for microsphere immobilization and isolation of soft tissue. The microspheres exhibited excellent tissue support and degradation properties, their high specific surface area enhanced tissue remodeling, and their good conductivity eliminated free radicals and induced macrophage M2 polarization, which were confirmed by tests of mechanical property, swelling and degradation, conductivity and assays of cellular biocompatibility, ROS generation, and macrophage phenotype. In vivo experiments using a rat mandibular defect model confirmed the excellent bone repair capabilities of the CMH system, and transcriptomics, metabolomics, and metabolic testing revealed that the CMH system upregulated the oxidative phosphorylation pathway of macrophage, enhancing mitochondrial respiration and ATP production. Mitochondrial tracing experiments demonstrated the transfer of macrophage mitochondria to preosteoblasts, resulting in enhanced metabolic activity and osteogenic differentiation of preosteoblasts. This study may be the first suggest that conductive biomaterials facilitate osteogenic immunomodulation through mitochondrial transfer, which provides a promising method for regulating the immune microenvironment and reveals a novel pathway by which M2 macrophages enhance osteogenesis.
Project description:To investigate the determinants of neuronal survival after traumatic brain injury, we compared the transcriptional profiles of dying (Fluoro-Jade-positive) and immediately adjacent surviving (Fluoro-Jade-negative) neurons from the CA3 subfield of the rat hippocampus 24 hours after experimental TBI. We found that hippocampal neurons that survive TBI invariably express high levels of genes that have cellular functions involved in survival, regeneration, development, proliferation, neuronal plasticity such as cAMP response element binding protein (CREB), brain-derived-neurotrophic factor (BDNF) and mitogen-activated protein kinase 1 (MAPK1). Dying neurons express high levels of genes involved in aberrant cell cycle progression, immune response, inflammation, oxidative stress and apoptosis such as Interleukin-1β (IL-1β), caspase 3 and B-cell linker (BLNK). We conclude that shifting the balance between the global levels of these proteins with pharmacotherapeutic drugs that induce expression of cell survival associated genes, is expected to alter the cellular rheostat that determines cell survival or cell death. Replicate pooled samples (approximately 600 laser capture microdissected hippocampal neurons per sample of dying neurons (labeled with Fluoro-Jade, a fluorescent stain for degenerating CNS neurons) and surviving neurons (Fluoro-Jade-negative) were hybridized in duplicate to rat Agilent whole genome arrays.
Project description:Transforming growth factor-M-NM-2 (TGF-M-NM-2) signalling controls a number of cerebral functions and dysfunctions including synaptogenesis, amyloid-M-NM-2 accumulation, apoptosis and excitotoxicity. Using cultured cortical neurons prepared from either wild type or transgenic mice over-expressing a TGF-M-NM-2 responsive luciferase reporter gene (SBE-Luc), we demonstrated a progressive loss of TGF-M-NM-2 signalling during neuronal maturation and survival. Moreover, we showed that neurons exhibit increasing amounts of the serine protease HtrA1 (high temperature responsive antigen 1) and corresponding cleavage products during both in vitro neuronal maturation and brain development. In parallel of its ability to promote degradation of TGF-M-NM-21, we demonstrated that blockage of the proteolytic activity of HtrA1 leads to a restoration of TGF-M-NM-2 signalling, subsequent overexpression of the serpin type -1 plasminogen activator inhibitor (PAI-1) and neuronal death. Altogether, we propose that the balance between HtrA1 and TGF-M-NM-2 could be one of the critical events controlling both neuronal maturation and developmental survival. Keywords: HtrA1 / neuronal survival / PAI-1 / TGF-M-NM-2 signalling / tPA Total RNA were extracted from 3 cultures of 2 DIV Human neurons. For each stage, equal amounts of each RNA were pooled and 5M-BM-5g were reverse-transcribed, labelled and hybridized on pangenomic microarrays. Each pool was hybridized in duplicate dye-swap independent experiments.