Biology subjects

Bonnevie, E. D.

Publications and source records attributed to Bonnevie, E. D..

4 recordsLinked to original sources

bioRxiv2022

Rapid Restoration of Cell Phenotype and Matrix Forming Capacity Following Transient Nuclear Softening

The dense extracellular matrix of connective tissues impedes cell migration and subsequent matrix formation at sites of injury. We recently employed transient nuclear softening via histone deacetylase inhibition with trichostatin A (TSA) treatment to overcome the stiff nuclear impediments to cell migration through dense tissues and electrospun matrices. Despite these positive findings, the long-term implications of transient nuclear softening on cell transcriptional phenotype and matrix formation capacity are unknown. To address this, we investigated the influence of transient TSA treatment on porcine meniscal cell behavior, beginning with the efficacy and reproducibility of transient TSA treatment on histone acetylation and chromatin remodeling in vitro and cell migration through native meniscus tissue. Within 3 days after cessation of transient TSA treatment, histone acetylation and chromatin remodeling returned to control levels. Following TSA treatment, endogenous cell migration through native meniscus tissue increased greater than 3-fold compared to controls. Importantly, meniscal cells completely restored their transcriptional phenotype and maintained their capacity to respond transcriptionally and functionally to a secondary pro-matrix stimuli (i.e., transforming growth factor {beta}3) within 7 days after cessation of TSA treatment. Towards translation, we also showed the feasibility of biomaterial-delivered TSA to increase endogenous cell migration to a wound edge ex vivo. Together, this work defines the efficacy, reproducibility, safety, and feasibility of future translational approaches for nuclear softening to treat dense connective tissue injuries.

genomics↗

bioRxiv2022

Anti-Inflammatory Tension-Activated Repair Patches Improve Repair After Intervertebral Disc Herniation

Conventional treatment for intervertebral disc herniation alleviates pain but does not repair the annulus fibrosus (AF), resulting in a high incidence of recurrent herniation and persistent disfunction. The lack of repair and the acute inflammation that arise after injury further compromises the disc and can result in disc-wide degeneration in the long term. To address this clinical need, we developed tension-activated repair patches (TARPs) for annular repair and the local delivery of bioactive anti-inflammatory factors. TARPs transmit physiologic strains to mechanically-activated microcapsules (MAMCs) embedded within, which activate and release encapsulated biomolecules in response to physiologic loading. Here, we demonstrate that the TARP design modulates implant biomechanical properties and regulates MAMC mechano-activation. Next, the FDA-approved anti-inflammatory molecule, interleukin 1 receptor antagonist, Anakinra, was loaded in TARPs and the effects of TARP-mediated annular repair and Anakinra delivery was evaluated in a model of annular injury in the goat cervical spine. TARPs showed robust integration with the native tissue and provided structural reinforcement at the injury site that prevented disc-wide aberrant remodeling resulting from AF detensioning. The delivery of Anakinra via TARP implantation improved the retention of disc biochemical composition through increased matrix deposition and retention at the site of annular injury. Anakinra delivery additionally attenuated the inflammatory response associated by scaffold implantation, decreasing osteolysis in adjacent vertebrae and preserving disc cellularity and matrix organization throughout the AF. These results demonstrate the translational and therapeutic potential of this novel TARP system for the treatment of intervertebral disc herniations. One Sentence SummaryTension-activated repair patches delivering bioactive anti-inflammatory factors improve healing in an in vivo goat cervical disc injury model.

bioengineering↗

bioRxiv2022

Mechano-epigenetic regulation of extracellular matrix homeostasis via Yap and Taz

Cells integrate mechanical cues to direct fate specification to maintain tissue function and homeostasis. While disruption of these cues is known to lead to aberrant cell behavior and chronic diseases, such as tendinopathies, the underlying mechanisms by which mechanical signals maintain cell function is not well understood. Here, we show using a novel model of tendon de-tensioning that loss of tensile cues in vivo acutely changes nuclear morphology, positioning, and expression of catabolic gene programs. Using paired ATAC/RNAseq, we further identify that a loss of cellular tension rapidly reduces chromatin accessibility in the vicinity of Yap/Taz genomic targets while also increasing expression of genes involved in matrix catabolism. Overexpression of Yap results in a reduction of chromatin accessibility at matrix catabolic gene loci, while also reducing transcriptional levels. Concordantly, depletion of Yap/Taz elevates matrix catabolic expression. Finally, we demonstrate that overexpression of Yap not only prevents the induction of a broad catabolic program following a loss of cellular tension, but also preserves the underlying chromatin state from force-induced alterations. Taken together, these results provide novel mechanistic details by which mechanical signals regulate tendon cell function to preserve matrix homeostasis through a Yap/Taz axis. Significance StatementCells integrate mechanical signals to regulate biological outputs within tissues. These processes are required for tissue function and homeostasis. Here, we show how mechanical cues (e.g. tension) directs tendon cell function and fate at a transcriptional and epigenetic level. Furthermore, we show that disruption of these mechanical cues leads to a disease-like cell state, indicating these mechanosensitive pathways could be important for diseases driven by perturbed mechanical signaling, such as tendinopathy. Finally, we demonstrate that genetic perturbation of a single protein can preserve cell and chromatin state following a loss of tension, supporting novel avenues for the development of innovative mechano-therapeutics.

cell biology↗

bioRxiv2022

Developmental Morphogens Direct Human Induced Pluripotent Stem Cells Towards an Annulus Fibrosus-like Cell Phenotype

Therapeutic interventions for intervertebral disc herniation remain scarce due to the inability of endogenous annulus fibrosus (AF) cells to respond to injury and drive tissue regeneration. Unlike other orthopaedic tissues, such as cartilage, delivery of exogenous cells to the site of annular injury remains underdeveloped, largely due to a lack of an ideal cell source and the invasive nature of cell isolation. Human induced pluripotent stem cells (iPSCs) can be differentiated to specific cell fates using biochemical factors and are, therefore, an invaluable tool for cell therapy approaches. While differentiation protocols have been developed for cartilage and fibrous connective tissues (e.g., tendon), the signals that regulate the induction and differentiation of human iPSCs towards the annulus fibrosus fate remain unknown. Here, we screened a number of candidate factors (and their combinations) and assessed the transcriptomic signatures of key signaling factors involved in embryonic AF development and differentiated function. The transcriptional signatures of treated cells were compared to those of mature human AF cells, and conditions that promoted expression of annulus fibrosus extracellular matrix genes and key transcription factors involved in embryonic AF development were identified. These findings represent an initial approach to guide human induced pluripotent stem cells towards an annulus fibrosus-like fate for cellular delivery strategies.

cell biology↗