Microglia play a critical role in maintaining neural function. While microglial activity follows a circadian rhythm, it is not clear how this intrinsic clock relates to their function, especially in ...stimulated conditions such as in the control of systemic energy homeostasis or memory formation. In this study, we found that microglia-specific knock-down of the core clock gene, Bmal1, resulted in increased microglial phagocytosis in mice subjected to high-fat diet (HFD)-induced metabolic stress and likewise among mice engaged in critical cognitive processes. Enhanced microglial phagocytosis was associated with significant retention of pro-opiomelanocortin (POMC)-immunoreactivity in the mediobasal hypothalamus in mice on a HFD as well as the formation of mature spines in the hippocampus during the learning process. This response ultimately protected mice from HFD-induced obesity and resulted in improved performance on memory tests. We conclude that loss of the rigorous control implemented by the intrinsic clock machinery increases the extent to which microglial phagocytosis can be triggered by neighboring neurons under metabolic stress or during memory formation. Taken together, microglial responses associated with loss of Bmal1 serve to ensure a healthier microenvironment for neighboring neurons in the setting of an adaptive response. Thus, microglial Bmal1 may be an important therapeutic target for metabolic and cognitive disorders with relevance to psychiatric disease.
Synthetic hydrogels have been widely adopted as well-defined matrices for three-dimensional (3D) cell culture, with increasing interest in systems that enable the co-culture of multiple cell types ...for probing both cell–matrix and cell–cell interactions in studies of tissue regeneration and disease. We hypothesized that the unique dynamic covalent chemistry of self-healing hydrogels could be harnessed for not only the encapsulation and culture of human cells but also the subsequent construction of layered hydrogels for 3D co-cultures. To test this, we formed hydrogels using boronic acid-functionalized polymers and demonstrated their self-healing in the presence of physiologically relevant cell culture media. Two model human cell lines, MDA-MB-231 breast cancer cells and CCL151 pulmonary fibroblasts, were encapsulated within these dynamic materials, and good viability was observed over time. Finally, self-healing of cut hydrogel “blocks” laden with these different cell types was used to create layered hydrogels for the generation of a dynamic co-culture system. This work demonstrates the utility of self-healing materials for multidimensional cultures and establishes approaches broadly useful for a variety of biological applications.
Microglia are brain immune cells responsible for immune surveillance. Microglial activation is, however, closely associated with neuroinflammation, neurodegeneration, and obesity. Therefore, it is ...critical that microglial immune response appropriately adapts to different stressors. The circadian clock controls the cellular process that involves the regulation of inflammation and energy hemostasis. Here, we observed a significant circadian variation in the expression of markers related to inflammation, nutrient utilization, and antioxidation in microglial cells isolated from mice. Furthermore, we found that the core clock gene-Brain and Muscle Arnt-like 1 (
) plays a role in regulating microglial immune function in mice and microglial BV-2 cells by using quantitative RT-PCR.
deficiency decreased gene expression of pro-inflammatory cytokines, increased gene expression of antioxidative and anti-inflammatory factors in microglia. These changes were also observed in
knock-down microglial BV-2 cells under lipopolysaccharide (LPS) and palmitic acid stimulations. Moreover, Bmal1 deficiency affected the expression of metabolic associated genes and metabolic processes, and increased phagocytic capacity in microglia. These findings suggest that
is a key regulator in microglial immune response and cellular metabolism.
Many cell behaviors are significantly affected by cell culture geometry, though it remains unclear which geometry from two‐ to three‐dimensional (2D–3D) culture is appropriate for probing a specific ...cell function and mimicking native microenvironments. Toward addressing this, we established a 2.5D culture geometry, enabling initial cell spreading while reducing polarization to bridge between 2D and 3D geometries, and examined the responses of wound healing cells, human pulmonary fibroblasts, within it. To achieve this, we used engineered biomimetic hydrogels formed by photopolymerization, creating robust layered hydrogels with spread fibroblasts at the interface. We found that fibroblast responses were similar between 2D and 2.5D culture and different from 3D culture, with some underlying differences in mechanotransduction. These studies established the 2.5D cell culture geometry in conjunction with biomimetic synthetic matrices as a useful tool for investigations of fibroblast activation with relevance to the study of other cell functions and types.
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Healthy function of the gut microenvironment is dependent on complex interactions between the bacteria of the microbiome, epithelial and immune (host) cells, and the surrounding ...tissue. Misregulation of these interactions is implicated in disease. A range of tools have been developed to study these interactions, from mechanistic studies to therapeutic evaluation. In this Digest, we highlight select tools at the cellular and molecular level for probing specific cell-microenvironment interactions. Approaches are overviewed for controlling and probing cell-cell interactions, from transwell and microfluidic devices to engineered bacterial peptidoglycan fragments, and cell-matrix interactions, from three-dimensional scaffolds to chemical handles for in situ modifications.
Activation of fibroblasts is pivotal for wound healing; however, persistent activation leads to maladaptive processes and is a hallmark of fibrosis, where disease mechanisms are only partially ...understood. Human in vitro model systems complement in vivo animal models for both hypothesis testing and drug evaluation to improve the identification of therapeutics relevant to human disease. Despite advances, a challenge remains in understanding the dynamics of human fibroblast responses to complex microenvironment stimuli, motivating the need for more advanced tools to investigate fibrotic mechanisms. This work established approaches for assessing the temporal dynamics of these responses using genetically encoded fluorescent reporters of alpha smooth muscle actin expression, an indicator of fibroblast activation. Specifically, we created a toolset of human lung fibroblast reporter cell lines from different origins (male, female; healthy, idiopathic pulmonary fibrosis) and used three different versions of the reporter with the fluorescent protein modified to exhibit different temporal stabilities, providing temporal resolution of protein expression processes over a range of timescales. Using this toolset, we demonstrated that reporters provide insight into population shifts in response to both mechanical and biochemical cues that are not detectable by traditional end point assessments with differential responses based on cell origin. Furthermore, individual cells can also be tracked over time, with opportunities for comparison to complementary end point measurements. The establishment of this reporter toolset enables dynamic cell investigations that can be translated into more complex synthetic culture environments for elucidating disease mechanisms and evaluating therapeutics for lung fibrosis and other complex biological processes more broadly.
Despite advancements in procedures and patient care, mortality rates for neonatal recipients of the Norwood procedure, a palliation for single ventricle congenital malformations, remain high due to ...the use of a fixed-diameter blood shunt. In this study, a new geometrically tunable blood shunt was investigated to address limitations of the current treatment paradigm (e.g., Modified Blalock-Taussig Shunt) by allowing for controlled modulation of blood flow through the shunt to accommodate physiological changes due to the patient's growth. First, mathematical and computational cardiovascular models were established to investigate the hemodynamic requirements of growing neonatal patients with shunts and to inform design criteria for shunt diameter changes. Then, two stages of prototyping were performed to design, build and test responsive hydrogel systems that facilitate tuning of the shunt diameter by adjusting the hydrogel's degree of crosslinking. We examined two mechanisms to drive crosslinking: infusion of chemical crosslinking agents and near-UV photoinitiation. The growth model showed that 15-18% increases in shunt diameter were required to accommodate growing patients' increasing blood flow; similarly, the computational models demonstrated that blood flow magnitudes were in agreement with previous reports. These target levels of diameter increases were achieved experimentally with model hydrogel systems. We also verified that the photocrosslinkable hydrogel, composed of methacrylated dextran, was contact-nonhemolytic. These results demonstrate proof-of-concept feasibility and reflect the first steps in the development of this novel blood shunt. A tunable shunt design offers a new methodology to rebalance blood flow in this vulnerable patient population during growth and development.
Adoptive T‐cell therapies (ATCTs) are increasingly important for the treatment of cancer, where patient immune cells are engineered to target and eradicate diseased cells. The biomanufacturing of ...ATCTs involves a series of time‐intensive, lab‐scale steps, including isolation, activation, genetic modification, and expansion of a patient's T‐cells prior to achieving a final product. Innovative modular technologies are needed to produce cell therapies at improved scale and enhanced efficacy. In this work, well‐defined, bioinspired soft materials are integrated within flow‐based membrane devices for improving the activation and transduction of T‐cells. Hydrogel coated membranes (HCM) functionalized with cell‐activating antibodies are produced as a tunable biomaterial for the activation of primary human T‐cells. T‐cell activation utilizing HCMs lead to highly proliferative T‐cells that express a memory phenotype. Further, transduction efficiency is improved by several folds over static conditions by using a tangential flow filtration (TFF) flow‐cell, commonly used in the production of protein therapeutics, to transduce T‐cells under flow. The combination of HCMs and TFF technology leads to increased cell activation, proliferation, and transduction compared to current industrial biomanufacturing processes. The combined power of biomaterials with scalable flow‐through transduction techniques provides future opportunities for improving the biomanufacturing of ATCTs.
Well‐defined, bioinspired soft materials are integrated within scalable, flow‐based membrane devices for improving the activation and transduction of T‐cells, which are essential steps in the production of adoptive T‐cell therapies. These innovative technologies provide opportunities for improving the manufacturing of cell therapies.
Epstein-Barr virus (EBV) is a DNA tumor virus responsible for 1 to 2% of human cancers including subtypes of Burkitt's lymphoma, Hodgkin's lymphoma, gastric carcinoma, and nasopharyngeal carcinoma ...(NPC). Persistent latent infection drives EBV-associated tumorigenesis. Epstein-Barr nuclear antigen 1 (EBNA1) is the only viral protein consistently expressed in all EBV-associated tumors and is therefore an attractive target for therapeutic intervention. It is a multifunctional DNA binding protein critical for viral replication, genome maintenance, viral gene expression, and host cell survival. Using a fragment-based approach and x-ray crystallography, we identify a 2,3-disubstituted benzoic acid series that selectively inhibits the DNA binding activity of EBNA1. We characterize these inhibitors biochemically and in cell-based assays, including chromatin immunoprecipitation and DNA replication assays. In addition, we demonstrate the potency of EBNA1 inhibitors to suppress tumor growth in several EBV-dependent xenograft models, including patient-derived xenografts for NPC. These inhibitors selectively block EBV gene transcription and alter the cellular transforming growth factor-β (TGF-β) signaling pathway in NPC tumor xenografts. These EBNA1-specific inhibitors show favorable pharmacological properties and have the potential to be further developed for the treatment of EBV-associated malignancies.
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