Stiffness gradient hydrogels are a useful platform for studying mechanical interactions between cells and their surrounding environments. Here, we developed linear stiffness gradient hydrogels by controlling the polymerization of gelatin methacryloyl (GelMA) via differential UV penetration with a gradient photomask. Based on previous observations, a stiffness gradient GelMA hydrogel was created ranging from ~ 4 to 13 kPa over 15 mm (0.68 kPa/mm), covering the range of physiological tissue stiffness from fat to muscle, thereby allowing us to study stem cell mechanosensation and differentiation. Adipose-derived stem cells on these gradient hydrogels showed no durotaxis, which allowed for the screening of mechanomarker expression without confounding directed migration effects. In terms of morphological markers, the cell aspect ratio showed a clear positive correlation to the underlying substrate stiffness, while no significant correlation was found in cell size, nuclear size, or nuclear aspect ratio. Conversely, expression of mechanomarkers (i.e. Lamin A, YAP, and MRTFa) all showed a highly significant correlation to stiffness, which could be disrupted via inhibition of non-muscle myosin or Rho/ROCK signalling. Furthermore, we showed that cells plated on stiffer regions became stiffer themselves, and that stem cells showed stiffness-dependent differentiation to fat or muscle as has been previously reported in the literature.

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Background The prevalence of sleep‐disordered breathing in children is underestimated due to impediments in detection and diagnosis. Consequently, delayed management may affect the quality of life and the growth and development of a child. Due to their patient demographic, orthodontists are optimally positioned to identify those at risk of sleep‐disordered breathing and make referrals for investigation and management. This study aims to determine the prevalence of children at risk of sleep‐disordered breathing in an Australian orthodontic population. Methods A 1‐year retrospective study was conducted in an urban Western Australian private orthodontic practice with two branches in similar socioeconomic demographics. The responses of new patients to a modified paediatric sleep questionnaire and standard medical history form were recorded. Results In 1209 patients (4–18 years), 7.3% were at risk of sleep‐disordered breathing. An association between sex and the potential risk of sleep‐disordered breathing was found with 11% of males at risk of sleep‐disordered breathing compared to 7% of females (P = 0.012). Conclusions The relatively high prevalence of children at risk of sleep‐disordered breathing presenting for orthodontic care presents an opportunity to identify at‐risk individuals through routine use of the paediatric sleep questionnaire. This would facilitate early referral for diagnosis and management of sleep‐disordered breathing.