Micro-engineered devices for assessing cellular responses to mechanical stimulation of ex vivo tissues

下肢假肢使用者的软组织面临着独特的生物力学挑战。虽然不打算承受高负荷和变形，但它成为了残体-假体复合体内的承重结构。因此，深部软组织层可能会受损，导致深部组织损伤（DTI）。虽然相当大的努力已经进入DTI研究的固定的个人，只有很少知道的病因学和特定人群的风险因素截肢者。在理解什么机制有助于生物安全和生物力学上合理的假体配合方面存在明显的差距。因此，需要新的信息来推进未来的身体-设备接口设计和症状管理。考虑到这一点，了解在细胞和组织水平上发生了什么，以应对假体使用所产生的力是至关重要的。 为了解决在组织和细胞水平上缺乏理解的问题，需要新的工具。芯片上器官（OOC）是一个新兴领域，其建立在用于生物应用（芯片上实验室、微流体、细胞工程）的微工程方法的技术进步的基础上，以开发再现组织的体内功能和生理化学环境的体外系统。然而，虽然已经开发了各种各样的基于细胞培养的OOC模型，但它们不能完全复制体内组织的复杂性，并且很少有基于芯片组织的模型（其中保持完整的组织样品）的报道。考虑到OOC技术的好处（精确控制的流体流动、复用能力、对局部细胞环境的控制等），存在开发用于维持和分析其细胞和细胞外基质结构被保留的离体组织的新微系统的令人兴奋的机会。这样的系统将非常适合于监测组织损伤和重塑响应于机械力的新的调查，无论是在短期（小时）和长期（周）。 广泛用于制造OOC器件的基于光刻机的软光刻方法非常适合于机械刺激的应用。用于施加拉伸的方法已被广泛报道，尽管主要用于单层和多层细胞培养系统（例如，种子“芯片上的肺”）。然而，基于压缩的生物力学刺激很少被探索。因此，该项目的目的是开发第一个离体组织OOC系统的例子，该系统在应用受控负荷条件的同时，优化了体外维持骨骼肌的功能。该系统将被设计为能够对组织进行活细胞显微镜检查，并适用于其他组织类型（例如皮肤、血管）。

The soft tissue of lower-limb prosthetic users encounters unique biomechanical challenges. Although not intended to tolerate high loads and deformation, it becomes a weight-bearing structure within the residuum-prosthesis-complex. Consequently, deep soft tissue layers may be damaged, resulting in Deep Tissue Injury (DTI). Whilst considerable effort has gone into DTI research on immobilised individuals, only little is known about the aetiology and population-specific risk factors in amputees. There is a clear gap in understanding what mechanisms contribute to a biologically safe and biomechanically sound prosthetic fit. Therefore, new information is necessary to advance future body-device interface designs and management of symptoms. Considering this, it is fundamental to understand what is happening at the cellular and tissue-level in response to forces resulting from prosthetic use. Research problem To address this lack of understanding at the tissue and cellular level, new tools are required. Organ-on-a-chip (OOC) is an emerging area that builds upon technological advances in micro-engineering methods for biological applications (lab-on-a-chip, microfluidics, cell engineering) to develop in vitro systems that recapitulate the in vivo functions and physiochemical environment of tissues. However, whilst a diverse range of cell-culture based OOC models have been developed, they cannot fully replicate the complexity of tissues in vivo and there are few reports of on-chip tissue-based models (where intact tissue samples are maintained). Given the benefits of OOC technologies (precisely controlled fluid flows, ability to multiplex, control over the local cellular environment etc.), exciting opportunities exist to develop new microsystems for maintaining and analysing ex vivo tissue whose cellular and extracellular matrix architecture is preserved. Such systems would be well suited to novel investigations into monitoring tissue damage and remodelling in response to mechanical forces, both in the short-term (hours) and long-term (weeks). The elastomer-based soft lithography approaches widely used to create OOC devices are well suited to the application of mechanical stimuli. Methods for applying stretch have been widely reported, though primarily for mono- and multi- layer cell culture systems (e.g. the seminal "lung-on-a-chip"). However, compression-based biomechanical stimuli have been little explored. Therefore, the aim of this project is to develop the first example of an ex vivo tissue-based OOC system optimised for maintaining skeletal muscle in vitro whilst applying controlled loading conditions. The system will be designed to enable live-cell microscopy of the tissue and to be adaptable for use other tissue types (e.g. skin, vascular).