Using design thinking to create and implement a 3D digital library of anatomical specimens.

Design thinking (DT) is a five-stage process (empathize, define, ideate, prototype, and test) that guides the creation of user-centered solutions to complex problems. DT is in common use outside of science but has rarely been applied to anatomical education. The use of DT in this study identified the need for flexible access to anatomical specimens outside of the anatomy laboratory and guided the creation of a digital library of three-dimensional (3D) anatomical specimens (3D Anatomy Viewer). To test whether the resource was fit for purpose, a mixed-methods student evaluation was undertaken. Student surveys (n = 46) were employed using the system usability scale (SUS) and an unvalidated acceptability questionnaire. These verified that 3D Anatomy Viewer was usable (SUS of 72%) and acceptable (agreement range of 77%-93% on all Likert-type survey statements, Cronbach's alpha = 0.929). Supplementary interviews (n = 5) were analyzed through content analysis and revealed three main themes: (1) a credible online supplementary learning resource; (2) learning anatomy with 3D realism and interactivity; (3) user recommendations for expanding the number of anatomical models, test questions, and gamification elements. These data demonstrate that a DT framework can be successfully applied to anatomical education for creation of a practical learning resource. Anatomy educators should consider employing a DT framework where student-centered solutions to learner needs are required.

A workflow for the creation of photorealistic 3D cadaveric models using photogrammetry.

Three-dimensional (3D) representations of anatomical specimens are increasingly used as learning resources. Photogrammetry is a well-established technique that can be used to generate 3D models and has only been recently applied to produce visualisations of cadaveric specimens. This study has developed a semi-standardised photogrammetry workflow to produce photorealistic models of human specimens. Eight specimens, each with unique anatomical characteristics, were successfully digitised into interactive 3D models using the described workflow and the strengths and limitations of the technique are described. Various tissue types were reconstructed with apparent preservation of geometry and texture which visually resembled the original specimen. Using this workflow, an institution could digitise their existing cadaveric resources, facilitating the delivery of novel educational experiences.

Towards developing standard operating procedures for pre-clinical testing in the mdx mouse model of Duchenne muscular dystrophy.

This review discusses various issues to consider when developing standard operating procedures for pre-clinical studies in the mdx mouse model of Duchenne muscular dystrophy (DMD). The review describes and evaluates a wide range of techniques used to measure parameters of muscle pathology in mdx mice and identifies some basic techniques that might comprise standardised approaches for evaluation. While the central aim is to provide a basis for the development of standardised procedures to evaluate efficacy of a drug or a therapeutic strategy, a further aim is to gain insight into pathophysiological mechanisms in order to identify other therapeutic targets. The desired outcome is to enable easier and more rigorous comparison of pre-clinical data from different laboratories around the world, in order to accelerate identification of the best pre-clinical therapies in the mdx mouse that will fast-track translation into effective clinical treatments for DMD.

Reduced muscle necrosis and long-term benefits in dystrophic mdx mice after cV1q (blockade of TNF) treatment.

Tumour necrosis factor (TNF) is a potent inflammatory cytokine that appears to exacerbate damage of dystrophic muscle in vivo. The monoclonal murine specific antibody cV1q that specifically neutralises murine TNF demonstrated significant anti-inflammatory effects in dystrophic mdx mice. cV1q administration protected dystrophic skeletal myofibres against necrosis in both young and adult mdx mice and in adult mdx mice subjected to 48 h voluntary wheel exercise. Long-term studies (up to 90 days) in voluntarily exercised mdx mice showed beneficial effects of cV1q treatment with reduced histological evidence of myofibre damage and a striking decrease in serum creatine kinase levels. However, in the absence of exercise long-term cV1q treatment did not reduce necrosis or background pathology in mdx mice. An additional measure of well-being in the cV1q treated mice was that they ran significantly more than control mdx mice.

Three-dimensional optical coherence tomography of whole-muscle autografts as a precursor to morphological assessment of muscular dystrophy in mice.

Three-dimensional optical coherence tomography (3D-OCT) is used to evaluate the structure and pathology of regenerating mouse skeletal muscle autografts for the first time. The death of myofibers with associated inflammation and subsequent new muscle formation in this graft model represents key features of necrosis and inflammation in the human disease Duchenne muscular dystrophy. We perform 3D-OCT imaging of excised autografts and compare OCT images with coregistered histology. The OCT images readily distinguish the necrotic and inflammatory tissue of the graft from the intact healthy muscle fibers in the underlying host tissue. These preliminary findings suggest that, with further development, 3D-OCT could be used as a tool for the evaluation of small-animal muscle morphology and pathology, in particular, for analysis of mouse models of muscular dystrophy.

Implications of cross-talk between tumour necrosis factor and insulin-like growth factor-1 signalling in skeletal muscle.

1. Inflammation, particularly the pro-inflammatory cytokine tumour necrosis factor (TNF), increases necrosis of skeletal muscle. Depletion of inflammatory cells, such as neutrophils, cromolyn blockade of mast cell degranulation or pharmacological blockade of TNF reduces necrosis of dystrophic myofibres in the mdx mouse model of the lethal childhood disease Duchenne muscular dystrophy (DMD). 2. Insulin-like growth factor-1 (IGF-1) is a very important cytokine for maintenance of skeletal muscle mass and the transgenic overexpression of IGF-1 within muscle cells reduces necrosis of dystrophic myofibres in mdx mice. Thus, IGF-1 usually has the opposite effect to TNF. 3. Activation of TNF signalling via the c-Jun N-terminal kinase (JNK) can inhibit IGF-1 signalling by phosphorylation and conformational changes in insulin receptor substrate (IRS)-1 downstream of the IGF-1 receptor. Such silencing of IGF-1 signalling in situations where inflammatory cytokines are elevated has many implications for skeletal muscle in vivo. 4. The basis for these interactions between TNF and IGF-1 is discussed with specific reference to clinical consequences for myofibre necrosis in DMD and also for the wasting (atrophy) of skeletal muscles that occurs in very old people and in cachexia associated with inflammatory disorders.

Reduced necrosis of dystrophic muscle by depletion of host neutrophils, or blocking TNFalpha function with Etanercept in mdx mice.

Necrosis of skeletal muscle fibres in the lethal childhood myopathy Duchenne Muscular Dystrophy results from deficiency of the cell membrane associated protein, dystrophin. We test the hypothesis in dystrophin-deficient mice, that the initial sarcolemmal breakdown resulting from dystrophin deficiency is exacerbated by inflammatory cells, specifically neutrophils, and that cytokines, specifically Tumour Necrosis Factor alpha (TNFalpha), contribute to myofibre necrosis. Antibody depletion of host neutrophils resulted in a delayed and significantly reduced amount of skeletal muscle breakdown in young dystrophic mdx mice. A more striking and prolonged protective effect was seen after pharmacological blockade of TNFalpha bioactivity using Etanercept. The extent of exercise induced myofibre necrosis in adult mdx mice after voluntarily wheel exercise was also reduced after Etanercept administration. These data show a clear role for neutrophils and TNFalpha in necrosis of dystrophic mdx muscle in vivo. Etanercept is a highly specific anti-inflammatory drug, widely used clinically, and potential application to muscular dystrophies is suggested by this reduced breakdown of mdx skeletal muscle.

Cromolyn administration (to block mast cell degranulation) reduces necrosis of dystrophic muscle in mdx mice.

Duchenne muscular dystrophy is a lethal muscle wasting disorder, resulting from mutations in the gene encoding for the skeletal muscle protein dystrophin. The absence of functional dystrophin leaves the muscle membrane vulnerable to damage during contraction. Damage initially occurs as 'tears' in the membrane, this damage can be exacerbated by the inflammatory response leading to myofibre necrosis rather than repair. Mast cells resident within skeletal muscle represent an immediate source of pro-inflammatory cytokines. We hypothesise that blockade of mast cell degranulation would reduce the extent of myofibre necrosis in the mdx mouse. Daily cromolyn injections were performed on young and exercised adult mdx mice and histological analysis confirmed that mast cell degranulation contributes to myofibre necrosis. This research identified high biological variation between individual mdx mice in the severity of the dystrophic pathology, and supported a relationship between extent of muscle damage in adult mdx mice and their individual enthusiasm for voluntary wheel running.