Project description:Foreign body reaction is one of the most important limiting factors to the clinical translation of implantable bioelectronics. The experiment compares the process of foreign body reaction, following the implantation of a silicon device in a mouse peripheral nerve, to that of peripheral nerve injury, following nerve crushing. Both processes are also compared to a naïve peripheral nerve from an uninjured mouse. The endpoints are day 1, 4, 7, 14 and 28 days.
Project description:Polypropylene meshes that are commonly used for surgical groin hernia repair may trigger granulomatous foreign body reactions. Here, we show that asymptomatic patients display mesh-associated inflammatory granulomas long after surgery, which are dominated by monocyte-derived macrophages. In mice, subdermal mesh implantation induces a rapid and strong myeloid cell accumulation, without substantial attenuation for up to 90 days. Myeloid cells segregate into distinct macrophage subsets with separate spatial distribution, activation profiles and functional properties. Protein mass spectrometry confirms the inflammatory nature of the foreign body reaction, as characterized by cytokines, complement activation and immunoglobulin deposition.
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: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:Polymeric elastomers are extensively employed to fabricate implants intended for prolonged implantation. However, implantation of the elastomers can induce strong immune rejection reaction known as foreign body response (FBR), resulting in the rejection of foreign implants and thereby diminishing their in vivo efficacy. Herein, we present a group of immunocompatible elastomers, termed easy-to-synthesize vinyl-based anti-FBR dense elastomers (EVADE), synthesized via a straightforward and scalable method. In contrast to the pronounced immune reaction triggered by the commonly used implantable elastomers, EVADE materials effectively suppress the inflammation and long-term capsule formation in subcutaneous models of rodents and non-human primates for at least one year and two months, respectively. Implantation of EVADE materials significantly reduces the expression of inflammation-related proteins S100A8/A9 in adjacent tissues compared to polydimethylsiloxane (PDMS). We also show that inhibition or knockout of S100A8/A9 leads to substantial attenuation of fibrosis in mice, suggesting a target for fibrosis inhibition. Continuous subcutaneous insulin infusion (CSII) catheters constructed from EVADE elastomers demonstrate significantly improved longevity and performance compared to commercial catheters. The EVADE materials reported here may enhance and extend function in various medical devices by resisting local immune responses to implanted biomaterials.
Project description:Polymeric elastomers are extensively employed to fabricate implants intended for prolonged implantation. However, implantation of the elastomers can induce strong immune rejection reaction known as foreign body response (FBR), resulting in the rejection of foreign implants and thereby diminishing their in vivo efficacy. Herein, we present a group of immunocompatible elastomers, termed easy-to-synthesize vinyl-based anti-FBR dense elastomers (EVADE), synthesized via a straightforward and scalable method. In contrast to the pronounced immune reaction triggered by the commonly used implantable elastomers, EVADE materials effectively suppress the inflammation and long-term capsule formation in subcutaneous models of rodents and non-human primates for at least one year and two months, respectively. Implantation of EVADE materials significantly reduces the expression of inflammation-related proteins S100A8/A9 in adjacent tissues compared to polydimethylsiloxane (PDMS). We also show that inhibition or knockout of S100A8/A9 leads to substantial attenuation of fibrosis in mice, suggesting a target for fibrosis inhibition. Continuous subcutaneous insulin infusion (CSII) catheters constructed from EVADE elastomers demonstrate significantly improved longevity and performance compared to commercial catheters. The EVADE materials reported here may enhance and extend function in various medical devices by resisting local immune responses to implanted biomaterials.
Project description:Although macrophage-epithelioid cell (EPC)-giant cell (GC) differentiation is acknowledged in foreign body reaction (FBR), the exact molecular features remain elusive. To discover the molecular profiles of EPC and GC, we analyzed mouse sponge and silk FBRs by integrating single-cell RNA-sequencing (scRNA-seq) and spatial sequencing.
Project description:Although macrophage-epithelioid cell (EPC)-giant cell (GC) differentiation is acknowledged in foreign body reaction (FBR), the exact molecular features remain elusive. To discover the molecular profiles of EPC and GC, we analyzed mouse sponge and silk FBRs by integrating single-cell RNA-sequencing (scRNA-seq) and spatial sequencing.
Project description:Mechanical stress is a measure of internal resistance exhibited by a body or material when external forces, such as compression, tension, bending, etc. are applied. The study of mechanical stress on health and aging is a continuously growing field, as major changes to the extracellular matrix and cell-to-cell adhesions can result in dramatic changes to tissue stiffness during aging and diseased conditions. For example, during normal aging, many tissues including the ovaries, skin, blood vessels, and heart exhibit increased stiffness, which can result in a significant reduction in function of that organ. As such, numerous model systems have recently emerged to study the impact of mechanical and physical stress on cell and tissue health, including cell-culture conditions with matrigels and other surfaces that alter substrate stiffness and ex vivo tissue models that can apply stress directly to organs like muscle or tendons. Here, we sought to develop a novel method in an in vivo, model organism setting to study the impact of mechanical stress on aging, by increasing substrate stiffness in solid agar medium of C. elegans. To our surprise, we found shockingly limited impact of growth of C. elegans on stiffer substrates, including limited effects on cellular health, gene expression, organismal health, stress resilience, and longevity. Overall, our studies reveal that altering substrate stiffness of growth medium for C. elegans have only mild impact on animal health and longevity; however, these impacts were not nominal and open up important considerations for C. elegans biologists in standardizing agar medium choice for experimental assays.