Spatiotemporal cell junction assembly in human iPSC-CM models of arrhythmogenic cardiomyopathy.

Arrhythmogenic cardiomyopathy (ACM) is an inherited cardiac disorder that causes life-threatening arrhythmias and myocardial dysfunction. Pathogenic variants in Plakophilin-2 (PKP2), a desmosome component within specialized cardiac cell junctions, cause the majority of ACM cases. However, the molecular mechanisms by which PKP2 variants induce disease phenotypes remain unclear. Here we built bioengineered platforms using genetically modified human induced pluripotent stem cell-derived cardiomyocytes to model the early spatiotemporal process of cardiomyocyte junction assembly in vitro. Heterozygosity for truncating variant PKP2R413X reduced Wnt/ß-catenin signaling, impaired myofibrillogenesis, delayed mechanical coupling, and reduced calcium wave velocity in engineered tissues. These abnormalities were ameliorated by SB216763, which activated Wnt/ß-catenin signaling, improved cytoskeletal organization, restored cell junction integrity in cell pairs, and improved calcium wave velocity in engineered tissues. Together, these findings highlight the therapeutic potential of modulating Wnt/ß-catenin signaling in a human model of ACM.

Muscle tissue engineering in fibrous gelatin: implications for meat analogs.

Bioprocessing applications that derive meat products from animal cell cultures require food-safe culture substrates that support volumetric expansion and maturation of adherent muscle cells. Here we demonstrate scalable production of microfibrous gelatin that supports cultured adherent muscle cells derived from cow and rabbit. As gelatin is a natural component of meat, resulting from collagen denaturation during processing and cooking, our extruded gelatin microfibers recapitulated structural and biochemical features of natural muscle tissues. Using immersion rotary jet spinning, a dry-jet wet-spinning process, we produced gelatin fibers at high rates (~ 100 g/h, dry weight) and, depending on process conditions, we tuned fiber diameters between ~ 1.3 ± 0.1 µm (mean ± SEM) and 8.7 ± 1.4 µm (mean ± SEM), which are comparable to natural collagen fibers. To inhibit fiber degradation during cell culture, we crosslinked them either chemically or by co-spinning gelatin with a microbial crosslinking enzyme. To produce meat analogs, we cultured bovine aortic smooth muscle cells and rabbit skeletal muscle myoblasts in gelatin fiber scaffolds, then used immunohistochemical staining to verify that both cell types attached to gelatin fibers and proliferated in scaffold volumes. Short-length gelatin fibers promoted cell aggregation, whereas long fibers promoted aligned muscle tissue formation. Histology, scanning electron microscopy, and mechanical testing demonstrated that cultured muscle lacked the mature contractile architecture observed in natural muscle but recapitulated some of the structural and mechanical features measured in meat products.

Topical NSAID therapy for musculoskeletal pain.

OBJECTIVE: Systematic reviews previously reported in the literature document that topical nonsteroidal anti-inflammatory drugs (NSAIDs) are effective in relieving pain in acute and chronic painful musculoskeletal disorders including osteoarthritis, tendonitis, and muscle strains. Because several topical NSAIDs are available, with important differences among the formulations, there is a need to address and summarize the evidence of their effectiveness and safety. DESIGN: We searched Medline and Cochrane CENTRAL databases for clinical trials and systematic reviews of topical NSAIDs in musculoskeletal pain, using the following keywords: "NSAID,""nonsteroidal,""antiinflammatory,""topical,""cream,""gel,""solution,""lotion,""patch,"plaster,""musculoskeletal,""tendonitis,""strain,""sprain,""trauma," and word roots "pain" and "arthritis." CONCLUSIONS: Topical NSAIDs may vary significantly in their absorption kinetics and pharmacodynamic effects, based on NSAID molecule and the formulation chosen. Some topical NSAID formulations have been shown to be more effective than placebo in multiple studies, or to have comparable efficacy and a better safety profile than oral NSAIDs for single joint osteoarthritis and acute muscle injuries. In acute and chronic low back pain, widespread musculoskeletal pain, and in peripheral neuropathic pain syndromes, the current evidence does not support the use of topical NSAIDs.