Project description:Mechanical stimulation is essential in tissue engineering and regenerative medicine for proper tissue maturation. However, conventional dynamic stimulation is typically achieved with uniaxial platforms, which limit functionality due to the oversimplified mechanics compared to the complex mechanical inputs of the human body. In this study, we explore human cell responses to stimulation using a humanoid robot shoulder and a uniaxial platform at equivalent strains. A flexible, biocompatible sensor monitoring in situ strains shows that external maximum forces of 25 N and 50 N during robot abduction-adduction motions lead to strains of approximately 3.5% and 9.5%, respectively. Additionally, we demonstrate in situ cell imaging by utilizing the transparency of the bioreactor membrane. The robot motions significantly enhance cell orientation and induce notable changes in gene and protein expression, particularly within the PI3K-Akt signaling pathway, compared to both static and uniaxial stimulation controls. These findings underscore the need to better match human biomechanics in bioreactor platforms to improve tissue engineering outcomes.
Project description:Tendon degeneration and injury often result in significant pain and functional impairment. Typically, tendon healing occurs through a scar-mediated response and may progress to chronic tendinopathy without timely intervention. However, the molecular mechanisms underlying early tendon repair remain poorly understood. Further investigation is also impeded by the limited availability of early tendon injury samples in clinical settings. In this study, we established a puncture-induced tendon injury model to investigate the molecular patterns and cellular subpopulations involved in early tendon injury across multiple time points. RNA sequencing identified seven gene sets with distinct expression profiles during the early stages of tendon injury. Single-cell RNA sequencing further revealed eight myeloid cell types and seven mesenchymal cell types participating in the tendon repair process. Together, these findings illuminate the molecular and cellular dynamics coordinating early tendon repair, providing insights that could inform future clinical treatments for tendinopathy and tendon injury.
Project description:Tendon degeneration and injury often result in significant pain and functional impairment. Typically, tendon healing occurs through a scar-mediated response and may progress to chronic tendinopathy without timely intervention. However, the molecular mechanisms underlying early tendon repair remain poorly understood. Further investigation is also impeded by the limited availability of early tendon injury samples in clinical settings. In this study, we established a puncture-induced tendon injury model to investigate the molecular patterns and cellular subpopulations involved in early tendon injury across multiple time points. RNA sequencing identified seven gene sets with distinct expression profiles during the early stages of tendon injury. Single-cell RNA sequencing further revealed eight myeloid cell types and seven mesenchymal cell types participating in the tendon repair process. Together, these findings illuminate the molecular and cellular dynamics coordinating early tendon repair, providing insights that could inform future clinical treatments for tendinopathy and tendon injury.
Project description:Rotator cuff injuries result in over 500,000 surgeries performed annually, an alarmingly high number of which fail. These procedures typically involve repair of the injured tendon and removal of the subacromial bursa. However, recent identification of a resident population of mesenchymal stem cells and inflammatory responsiveness of the bursa to tendinopathy indicate an unexplored biological role of the bursa in the context of rotator cuff disease. Therefore, we aimed to understand the clinical relevance of bursa-tendon crosstalk, characterize the biologic role of the bursa within the shoulder, and test the therapeutic potential for targeting the bursa. Proteomic profiling of patient bursa and tendon samples demonstrated that the bursa is activated by tendon injury. Using a rat to model rotator cuff injury and repair, tenotomy-activated bursa protected the intact tendon adjacent to the injured tendon and maintained the morphology of the underlying bone. The bursa also promoted an early inflammatory response in the injured tendon, initiating key players in wound healing. In vivo results were supported by targeted organ culture studies of the bursa. To examine the potential to therapeutically target the bursa, dexamethasone was delivered to the bursa, prompting a shift in cellular signaling towards modulating inflammation in the healing tendon. In conclusion, contrary to current clinical practice, the bursa should be retained to the greatest extent possible and provides a new therapeutically target for improving tendon healing outcomes.
Project description:Tendon from young and old donors was used for RNA-Seq analysis. The aim of the study was to identify differentially expressed tendon transcripts in ageing in order to to characterize molecular mechanisms associated with age-related changes in tendon.
Project description:Tendon injuries can occur due to sports related incidents, as a result of trauma to overuse or during disease or ageing. Tissue engineering can offer great potential in the treatment of a tendon injury. The preferred cell source is autologous in order to reduce immune response in the treated individual. However, in elderly patients age-related changes in metabolism of the implanted cells may affect results of such therapy. In this study the effect of donor age on synthetic activity of cells used for creation of tendon tissue-engineered constructs was investigated by using label-free proteomic comparison.
Project description:Synthetic Notch (synNotch) receptors are modular synthetic components that are genetically engineered into mammalian cells to detect signals presented by neighboring cells and respond by activating prescribed transcriptional programs. To date, synNotch has been used to program therapeutic cells and pattern morphogenesis in multicellular systems. However, cell-presented ligands have limited versatility for applications that require spatial precision, such as tissue engineering. To address this, we developed a suite of materials to activate synNotch receptors and serve as generalizable platforms for generating user-defined material-to-cell signaling pathways. First, we demonstrate that synNotch ligands, such as GFP, can be conjugated to cell- generated ECM proteins via genetic engineering of fibronectin produced by fibroblasts. We then used enzymatic or click chemistry to covalently link synNotch ligands to gelatin polymers to activate synNotch receptors in cells grown on or within a hydrogel. To achieve microscale control over synNotch activation in cell monolayers, we microcontact printed synNotch ligands onto a surface. We also patterned tissues comprising cells with up to three distinct phenotypes by engineering cells with two distinct synthetic pathways and culturing them on surfaces microfluidically patterned with two synNotch ligands. We showcase this technology by co-transdifferentiating fibroblasts into skeletal muscle or endothelial cell precursors in user-defined spatial patterns towards the engineering of muscle tissue with prescribed vascular networks. Collectively, this suite of approaches extends the synNotch toolkit and provides novel avenues for spatially controlling cellular phenotypes in mammalian multicellular systems, with many broad applications in developmental biology, synthetic morphogenesis, human tissue modeling, and regenerative medicine.
Project description:Synthetic Notch (synNotch) receptors are modular synthetic components that are genetically engineered into mammalian cells to detect signals presented by neighboring cells and respond by activating prescribed transcriptional programs. To date, synNotch has been used to program therapeutic cells and pattern morphogenesis in multicellular systems. However, cell-presented ligands have limited versatility for applications that require spatial precision, such as tissue engineering. To address this, we developed a suite of materials to activate synNotch receptors and serve as generalizable platforms for generating user-defined material-to-cell signaling pathways. First, we demonstrate that synNotch ligands, such as GFP, can be conjugated to cell- generated ECM proteins via genetic engineering of fibronectin produced by fibroblasts. We then used enzymatic or click chemistry to covalently link synNotch ligands to gelatin polymers to activate synNotch receptors in cells grown on or within a hydrogel. To achieve microscale control over synNotch activation in cell monolayers, we microcontact printed synNotch ligands onto a surface. We also patterned tissues comprising cells with up to three distinct phenotypes by engineering cells with two distinct synthetic pathways and culturing them on surfaces microfluidically patterned with two synNotch ligands. We showcase this technology by co-transdifferentiating fibroblasts into skeletal muscle or endothelial cell precursors in user-defined spatial patterns towards the engineering of muscle tissue with prescribed vascular networks. Collectively, this suite of approaches extends the synNotch toolkit and provides novel avenues for spatially controlling cellular phenotypes in mammalian multicellular systems, with many broad applications in developmental biology, synthetic morphogenesis, human tissue modeling, and regenerative medicine.
Project description:Tendons and ligaments are important biological structures in both humans and animals. They are part of dense connective tissue and are crucial to the functioning of the musculoskeletal system. However, they are commonly damaged due to age-related wear and tear, trauma or sports related incidents, which can lead to severe immobility for the individual and can lead to injury of other tissues and development of degenerative joint disease such as osteoarthritis. Tissue engineering can offer great potential in the treatment of tendon and ligament injury by seeking a biological replacement with fully regenerated autologenous tissue. This approach commonly involves an artificial ECM (scaffold) on which cell can proliferate and differentiate with subsequent new tissue generation. Fibrin is a natural scaffold with no expected toxic degradation or inflammatory reaction and can be used as an autologous scaffold for fibroblast from connective tissue to create a three dimensional structure. The purpose of this study was to compare the proteomic differences between native tendon, ligament and 3D tissue engineered tendon and ligament fibrin constructs.