Promoting differentiation of cultured myoblasts using biomimetic surfaces that present alpha-laminin-2 peptides

Application of biomimetic surfaces and 3D culture technology to study the role of extracellular matrix interactions in neurite outgrowth and inhibition

The microenvironment that cells experience during in vitro culture can often be far removed from the native environment they are exposed to in vivo. To recreate the physiological environment that developing neurites experience in vivo, we combine a well-established model of human neurite development with, functionalisation of both 2D and 3D growth substrates with specific extracellular matrix (ECM) derived motifs displayed on engineered scaffold proteins. Functionalisation of growth substrates provides biochemical signals more reminiscent of the in vivo environment and the combination of this technology with 3D cell culture techniques, further recapitulates the native cellular environment by providing a more physiologically relevant geometry for neurites to develop. This biomaterials approach was used to study interactions between the ECM and developing neurites, along with the identification of specific motifs able to enhance neuritogenesis within this model. Furthermore, this technology was employed to study the process of neurite inhibition that has a detrimental effect on neuronal connectivity following injury to the central nervous system (CNS). Growth substrates were functionalised with inhibitory peptides released from damaged myelin within the injured spinal cord (Nogo & OMgp). This model was then utilised to study the underlying molecular mechanisms that govern neurite inhibition in addition to potential mechanisms of recovery.

Uniaxially crumpled graphene as a platform for guided myotube formation

Graphene, owing to its inherent chemical inertness, biocompatibility, and mechanical flexibility, has great potential in guiding cell behaviors such as adhesion and differentiation. However, due to the two-dimensional (2D) nature of graphene, the microfabrication of graphene into micro/nanoscale patterns has been widely adopted for guiding cellular assembly. In this study, we report crumpled graphene, i.e., monolithically defined graphene with a nanoscale wavy surface texture, as a tissue engineering platform that can efficiently promote aligned C2C12 mouse myoblast cell differentiation. We imparted out-of-plane, nanoscale crumpled morphologies to flat graphene via compressive strain-induced deformation. When C2C12 mouse myoblast cells were seeded on the uniaxially crumpled graphene, not only were the alignment and elongation promoted at a single-cell level but also the differentiation and maturation of myotubes were enhanced compared to that on flat graphene. These results demonstrate the utility of the crumpled graphene platform for tissue engineering and regenerative medicine for skeletal muscle tissues.

A1603P and K1617del, Mutations in β-Cardiac Myosin Heavy Chain that Cause Laing Early-Onset Distal Myopathy, Affect Secondary Structure and Filament Formation In Vitro and In Vivo

Over 20 mutations in β-cardiac myosin heavy chain (β-MHC), expressed in cardiac and slow muscle fibers, cause Laing early-onset distal myopathy (MPD-1), a skeletal muscle myopathy. Most of these mutations are in the coiled-coil tail and commonly involve a mutation to a proline or a single-residue deletion, both of which are predicted to strongly affect the secondary structure of the coiled coil. To test this, we characterized the effects of two MPD-1 causing mutations: A1603P and K1617del in vitro and in cells. Both mutations affected secondary structure, decreasing the helical content of 15 heptad and light meromyosin constructs. Both mutations also severely disrupted the ability of glutathione S-transferase–light meromyosin fusion proteins to form minifilaments in vitro, as demonstrated by negative stain electron microscopy. Mutant eGFP-tagged β-MHC accumulated abnormally into the M-line of sarcomeres in cultured skeletal muscle myotubes. Incorporation of eGFP-tagged β-MHC into sarcomeres in adult rat cardiomyocytes was reduced. Molecular dynamics simulations using a composite structure of part of the coiled coil demonstrated that both mutations affected the structure, with the mutation to proline (A1603P) having a smaller effect compared to K1617del. Taken together, it seems likely that the MPD-1 mutations destabilize the coiled coil, resulting in aberrant myosin packing in thick filaments in muscle sarcomeres, providing a potential mechanism for the disease.

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It is unclear how mutations in the coiled coil of β-myosin heavy chain cause distal myopathy.

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A1603P and K1617del mutations reduce helicity and affect filament formation in vitro.

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eGFP-tagged β-myosin heavy chain abnormally accumulates at the M-line of sarcomeres in skeletal myotubes.

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Molecular dynamics simulations provide a molecular understanding for these experiments.

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Effects on structure and packing into the thick filament provide a molecular basis for the disease.

Evaluation of a range of mammalian and mosquito cell lines for use in Chikungunya virus research

Chikungunya virus (CHIKV) is becoming an increasing global health issue which has spread across the globe and as far north as southern Europe. There is currently no vaccine or anti-viral treatment available. Although there has been a recent increase in CHIKV research, many of these in vitro studies have used a wide range of cell lines which are not physiologically relevant to CHIKV infection in vivo. In this study, we aimed to evaluate a panel of cell lines to identify a subset that would be both representative of the infectious cycle of CHIKV in vivo, and amenable to in vitro applications such as transfection, luciferase assays, immunofluorescence, western blotting and virus infection. Based on these parameters we selected four mammalian and two mosquito cell lines, and further characterised these as potential tools in CHIKV research.