Restoring the Mechanosensation in Engineered Skin using Controllable Cellular and Extracellular Cues

机械感觉是感知外部世界和社会交流的必要条件。皮肤是我们最大的感觉器官，密集分布着负责感觉的神经末梢，如触觉、疼痛、压力和振动。该项目的长期目标是将感觉神经元整合到生物工程3D皮肤结构（BESCs）中，以研究皮肤的机械感觉和使用人类细胞的再生。BESCs中感觉神经元的生长、位置和类型将通过局部提供皮肤特定细胞类型分泌的特殊蛋白质以及局部电刺激来控制。该项目将产生积极的长期社会影响：1)为更广泛的研究团体提供一个生理相关的体外模型，以研究感觉神经元在发育和伤口愈合过程中的神经支配动力学；2)利用人体细胞评估候选药物的疗效/毒性。此外，该项目将通过为各级学生提供研究培训和专业机会，为STEM教育和劳动力发展做出贡献，并将大大有利于学生在生物材料，组织工程和神经科学领域的职业发展。培训活动包括：为期4周的暑期研究生训练营；研究生水平的课程；纵向整合项目（VIP），整合本科研究；涉及K-12学生的为期两周的暑期研究经验；还有一个为期两天的虚拟夏季研讨会，用于培训年轻研究人员。特定类型机械感觉的分子和细胞机制已被很好地描述。然而，关于是什么决定和指导皮肤体感觉神经元（SSN）和感觉末端器官的分支模式和适当的神经支配来调节机械感觉的知识有限。该项目的目标是通过空间控制的微环境线索诱导和控制工程皮肤的神经支配水平，包括3d图案的真皮细胞外基质（ECM）导管，毛囊表皮信号（如毛囊），以及通过无线电刺激在特定模式下分化的雪旺细胞（SCs）。目标1中的研究将识别促进或阻止SSN生长的ECM分子，并在BESCs中使用已识别的吸引/排斥ECM线索来引导神经末梢到达最终目的地。目标2的研究将使用有毛的BESC模型，并确定不同亚型的ssn对毛囊（有毛）和毛囊间（无毛）表皮的优先神经支配。目标3的研究将利用电分化方法在三维真皮中空间控制雪旺细胞命运的承诺，以调节局部髓鞘形成和ssn的功能。这个生物医学科学项目的关键知识价值是在使用人类细胞的3D皮肤微环境中，破译细胞和细胞外线索对神经支配和感觉神经元模式形成的个体影响。本研究还将通过解决在3D皮肤模型中控制神经支配的流行组织工程挑战，为工程做出贡献。线索驱动策略包括环境引导信号和集成的无线电生物接口，可以进一步适用于空间控制的神经支配和其他器官的工程。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Mechanosensation is essential for perceiving the external world and social exchange. The skin is our largest sensory organ and is densely populated with nerve endings responsible for senses, such as touch, pain, pressure, and vibration. The long-term goal of this project is to integrate sensory neurons into bioengineered 3D skin constructs (BESCs) to enable studying skin mechanosensation and regeneration using human cells. The growth, location, and type of sensory neurons in BESCs will be controlled by locally providing specialized proteins secreted by specific cell types of the skin, as well as through localized electrical stimulation. This project will make a positive societal impact in the long term by 1) providing a physiologically-relevant in vitro model to a broader research community to study the innervation dynamics of sensory neurons during development and wound healing; and 2) evaluating the efficacy/toxicity of drug candidates using human cells. In addition, this project will contribute to STEM education and workforce development by providing research training and professional opportunities for students at all levels and will significantly benefit students pursuing a career in the fields of biomaterials, tissue engineering, and neuroscience. Training activities include: a 4-week summer boot camp for graduate student training; a graduate-level course; a Vertically Integrated Program (VIP) to integrate undergraduate research; a 2-week summer research experience involving K-12 students; and a 2-day-long virtual summer symposium for training young researchers.The molecular and cellular mechanisms underlying the specific types of mechanosensation are well-characterized. Yet, there is limited knowledge about what determines and instructs the branching patterns and proper innervation of somatosensory neurons (SSN) and sensory end-organs in the skin to mediate mechanosensation. The goal of this project is to induce and control the level of innervation in engineered skin through spatially-controlled microenvironmental cues, including 3D-patterned dermal extracellular matrix (ECM) conduits, follicular epidermal signals (e.g., hair follicles), and Schwann cells (SCs) differentiated via wireless electrical stimulation in defined patterns. Studies in Goal 1 will identify the ECM molecules that promote or prevent SSN outgrowth and employ the identified attractive/repulsive ECM cues in BESCs to guide the nerve endings to their final destination. Studies in Goal 2 will use a hair-bearing BESC model and determine the preferential innervation of the follicular (hairy) and interfollicular (non-hairy) epidermis by different subtypes of SSNs. Studies in Goal 3 will leverage electrical differentiation approaches to spatially control the Schwann cell fate commitment in the 3D dermis to regulate local myelination and function of SSNs. The key intellectual merit of this project for biomedical sciences is to decipher the individual effects of cellular and extracellular cues on the innervation and pattern formation of sensory neurons in the context of a 3D skin microenvironment using human cells. This study will also contribute to engineering by addressing a prevailing tissue engineering challenge of controlling innervation in 3D skin models. The cue-driven strategy involving environmental guidance signals and integrated wireless electrical biointerfaces can further be adapted for spatially-controlled innervation and engineering of other organs.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.