Effects of three-dimensional macroporosity and matrix elasticity on the outcomes of stem cells based cartilage tissue regeneration

主要研究者：Han，Li-Hsin提案号：1605604干细胞的软骨再生为数百万遭受软骨损伤的人提供了巨大的希望，例如，骨关节炎该项目的总体目标是了解3D环境中的孔径和基质弹性如何调节基于干细胞的软骨再生。新型3D支架的构建块是带状和微米级水凝胶，可以交联以封装人间充质干细胞，并提供具有独立可调孔径、基质弹性和化学性质的环境。拟议的研究将提供有关实现完全基于干细胞的软骨修复所需的环境的有价值的信息。教育和推广的影响将通过加强参与学生的研究经验，新的研究生课程，以及涉及高中教师和代表性不足的K-12学生的活动来实现。该奖项由材料研究部的生物材料项目通过BioMaps项目共同资助。创伤和退行性疾病导致的关节软骨损伤是一个严重的健康问题。仅骨关节炎就影响了美国超过2700万人，预计在他们的一生中会影响1/2的人。软骨中的软骨细胞再生能力较差，如果不进行开放手术或其他侵入性干预，大多数关节损伤就无法愈合。自体软骨植入或ACI和微骨折技术是软骨修复的既定治疗方法，但这些方法通常受到软骨供应不足、持续软骨退化和纤维化软骨形成的限制，这些软骨不能提供足够的机械强度来维持身体负荷。基于干细胞的软骨再生为软骨损伤患者带来了巨大的希望。干细胞软骨形成的成功依赖于理想的细胞生态位，其提供适当协调的生态位特性，形成对软骨形成至关重要的关键要素，包括生物化学和生物物理学线索，以促进所需的干细胞生物活性。大孔是不小于典型细胞的孔隙空间，是一种非常有潜力的控制干细胞软骨分化的机械传感调节器。然而，三维小生境特性调节干细胞软骨形成的机制在很大程度上仍不清楚。目前缺乏一个支持生态位特性和干细胞生物活性之间复杂相互作用的基础研究平台。 鉴于干细胞如何响应我们体内的生态位特性的复杂性，可以轻松控制大孔隙率，基质弹性和细胞形态的三维生态位模型将有助于研究软骨形成的生态位效应的机制，并可能有一天导致理想的细胞生态位，以实现完全软骨修复的最终目标。该项目将通过使用可交联的微带来尝试实现这一目标的第一步，微带是过去几年出现的带状和微米级水凝胶，作为构建模型细胞龛的构建块，以提供孔径，细胞形状和弹性的巨大变化。微带提供以下功能以促进关于生态位组成如何影响干细胞软骨形成的全面研究：1）在三维中直接细胞包封，2）通过可调的大孔尺寸控制细胞形状，3）独立可调的生物化学和机械线索，以及4）互连的大孔以保留由细胞产生的ECM组分。研究人员利用大丝带实现了3个目标：1）建立一个3D模型，将人间充质干细胞（MSC）暴露于不同的大孔尺寸和基质弹性，并评估MSC在细胞形状，粘着斑，细胞骨架组织和转录因子活性方面的细胞特性; 2）确定大孔尺寸、基质弹性和相关的细胞性质如何影响人MSC的软骨形成分化;和3）：了解大孔隙和基质弹性如何影响软骨基质的产生和软骨细胞表型的稳定性。 如果成功，许多软骨损伤患者可以从开发的3D大孔细胞龛中受益。拟议的项目跨越多个学科，包括工程，生物和医学。学生进行拟议的研究将受益匪浅，通过接触到各种实验，包括有机合成，纳米压痕，干细胞培养和细胞分析。将开发新的研究生课程，将拟议的研究内容纳入其中，将研究成果从实验室转化为课堂。用于拟议项目的技术，如湿纺和脚手架制造，将有助于PI和工程学院主办的外展计划，为高中教师和代表性不足的K-12学生提供简短的讲座，夏令营和实践实验室经验。PI和co-PI将积极招募女性和少数民族学生进行拟议的研究。

PI: Han, Li-Hsin Proposal #: 1605604Cartilage regeneration by stem cells provides a tremendous hope for the millions of people who suffer from cartilage injuries, e.g., osteoarthritis. The overall objective of this project is to understand how pore size and matrix elasticity in a 3D environment regulate stem cell-based cartilage regeneration. The building blocks for the novel 3D scaffold are ribbon-like and microsized hydrogels that can be cross linked to encapsulate human mesenchymal stem cells and provide an environment with independently tunable pore size, matrix elasticity and chemical properties. The proposed studies will provide valuable information about the environment needed to achieve complete stem cell based cartilage repair. Educational and outreach impact will be achieved through enhanced research experiences for involved students, new graduate level courses, and activities involving high school teachers and underrepresented K-12 students. This award is co-funded by the Biomaterials program in the Division of Materials Research through the BioMaPs program.Articular cartilage injuries as a result of trauma and degenerative diseases present a serious health problem. Osteoarthritis alone affects more than 27 million people in the U.S. and is predicted to affect 1 in 2 people in their lifetime. Chondrocytes in the cartilage have a poor regenerative capacity, and most articular injuries cannot heal without open surgery or other invasive intervention. Autologous cartilage implantation, or ACI, and the microfracture technology are the established treatments for cartilage repair, but these methods are often limited by insufficient cartilage supply, continual cartilage degeneration, and the formation of fibrosis cartilages that do not provide sufficient mechanical strength to sustain body loads. Stem cell-based cartilage regeneration provides tremendous hopes for people suffering from cartilage injuries. The success of stem cell chondrogenesis relies on an ideal cell niche that provide properly orchestrated niche properties, forming the key elements that are crucial for chondrogenesis, including biochemical and biophysical cues, to promote the desired stem cell bioactivities. Macropores, the pore space no smaller than the typical cells, is a highly potential mechanosensing regulator to control the stem cell chondrogenic differentiation. However, the mechanisms by which niche properties in three-dimensions regulate stem cells chondrogenesis remain largely unclear. A platform to support the fundamental study on the complex interaction between niche properties and stem cell bioactivities is currently lacking. Given the complex nature of how stem cells respond to niche properties in our body, a three-dimensional niche model that can easily control macroporosity, matrix elasticity and cell morphology will facilitate a mechanistic study on the niche effect on chondrogenesis, and may one day lead to an ideal cell niche to realize the ultimate goal of complete cartilage repair. This project will conduct the first step to attempt such goal by using the crosslinkable microribbons, which are ribbon-like and micron-sized hydrogels that emerged in the past couple years, as the building blocks to construct the model cell niches to provide a vast variation of pore size, cell shape, and elasticity. The microribbons provide the following functions to facilitate a comprehensive study on how niche compositions impact stem cells chondrogenesis: 1) direct cell encapsulation in three dimensions, 2) control of cell shape by tunable macropore size, 3) independently tunable biochemical and mechanical cues, and 4) interconnected macroporosity to retain the ECM components produced by cells. Using macroribbons, the investigators address 3 aims: 1) To develop a 3D model that exposes human mesenchymal stems cells (MSC) to various macropore sizes and matrix elasticity, and to evaluate the cellular properties of MSC with regard to cell shape, focal adhesion, cytoskeleton organization, and transcription factor activity; 2) To determine how macropore size, matrix elasticity and the associated cellular properties influence the chondrogenic differentiation of human MSC; and 3): To understand how macroporosity and matrix elasticity influence the production of cartilage matrix and the stability of chondrocyte phenotypes. If successful, numerous patients suffering from cartilage injuries can benefit from the 3D macroporous cell niche developed. The proposed project spans multiple disciplines including engineering, biology and medicine. Students carrying out proposed research will benefit greatly by being exposed to a variety of experiments including organic synthesis, nanoindentation, stem cell cultivation and cellular assays. New graduate-level courses incorporating the elements from the proposed research will be developed to translate the research outcomes from lab benches to the classroom. Technology used for the proposed project, such as wet-spinning and scaffold fabrication, will be contributed to the outreaching programs hosted by the PI and the college of engineering, providing short lectures, summer camps, and hands-on lab experience to high school teachers and underrepresented K-12 students. The PI and co-PI will actively recruit female and minority students to conduct the proposed research.