CAREER: Engineering Three-dimensional Stem Cell Niche with Independently Tunable Biochemical and Mechanical Properties

1351289 Yang该项目的总体目标是开发一种具有生物化学和机械特性的新型干细胞生态位，可以独立调节;并使用该生态位阐明信号如何使用高通量策略在三维空间影响干细胞命运。 然而，指导干细胞的命运，使他们保持多能性或多能性，或他们致力于某种分化谱系，是组织工程和再生医学中的一个关键问题。 尽管有充分的证据表明干细胞对生化和机械线索都有反应，但了解给定环境中的全部信号如何指导细胞命运仍然是一个很大程度上未回答的问题，特别是在三维（3D）方面。 PI实验室最近的研究表明，生物化学和机械线索以非直观的方式相互作用，以调节干细胞的命运，这不能从干细胞对个体类型的利基线索的反应中预测。 拟议的研究旨在通过追求以下研究目标来促进对干细胞-生态位相互作用的理解：目标1。合成可降解聚合物作为干细胞龛的生物化学和机械“积木”，可同时独立交联形成互穿网络。开发具有可独立调节的微生态特性的仿生水凝胶微阵列，用于细胞的三维封装。以高通量的方式在3D组合水凝胶微阵列中检查交互式小生境信号对干细胞分化的影响。PI实施的系统和组合方法具有很高的智力价值。 此外，拟议的研究具有多个创新特征，包括开发具有独立控制生化和机械线索的互穿网络水凝胶;基于AFM和FRET的测定用于水凝胶刚度和降解的高通量表征;和新型的微加工平台，在3D中快速监测干细胞命运的通量筛选测定。更广泛的影响独立可调的线索，预计将包括一个强大的工具，以促进在3D干细胞的小生境相互作用的基本理解，从而解决了干细胞生物学和组织工程中的一个关键问题。 拟议研究的结果可能会大大加速基于干细胞的治疗，通过快速识别最佳线索来指导干细胞保持多能性或分化为功能成熟细胞。 正在进行的和新的教育计划针对从幼儿园到大学生的学生。 将为当地小学K-G1学生制定一项名为“修复人体的魔力”的外联方案。 PI还将为高中生开发一个为期一周的“组织工程嘉年华”夏令营，其中包括互动讲座、期刊俱乐部和实践活动，并将面向旧金山弗朗西斯科湾区贫困和少数民族背景的高中生。 总的来说，PI解决了一个具有更广泛影响的挑战性问题，并表现出对教育和推广活动与不同学生群体的当地学校的承诺。

1351289YangThe overall goal of this project is to develop a novel stem cell niche with biochemical and mechanical properties, which can be tuned independently; and to use this niche to elucidate how signals influence stem cell fate in three dimensions using high-throughput strategies.Intellectual meritStem cells have the potential to revolutionize medical therapies for a number of diseases. However, directing stem cell fate so that they maintain pluripotency or mutlipotency, or they commit to a certain differentiation lineage, is a critical problem in tissue engineering and regenerative medicine. Although there is ample evidence that stem cells respond to both biochemical and mechanical cues, understanding how the totality of signals in a given environment directs cell fate remains a largely unanswered question, especially in three dimensions (3D). Recent studies from the PI's laboratory indicate that biochemical and mechanical cues interact in a non-intuitive manner to regulate stem cell fate, which cannot be predicted from stem cell responses to individual type of niche cues. The proposed studies are designed to advance the understanding of stem cell-niche interactions by pursuing the following research objectives:Objective 1. Synthesize degradable polymers as biochemical and mechanical "building blocks" of stem cell niche that can crosslink simultaneously and independently to form an interpenetrating network.Objective 2. Develop biomimetic hydrogel microarrays with independently tunable nicheproperties for encapsulating cells in 3D.Objective 3. Examine the effects of interactive niche signaling on stem cell differentiation in 3D combinatorial hydrogel microarrays in a high-throughput manner.The systematic and combined approach implemented by the PI has a high intellectual merit. Additionally, the proposed studies carry multiple innovative features including the development of interpenetrating network hydrogels with independent control of biochemical and mechanical cues; AFM and FRET-based assays for high-throughput characterization of hydrogel stiffness and degradation; and novel microfabrication platforms and high-throughput screening assays for rapid monitoring of stem cell fate in 3D.Broader ImpactsThe proposed development of biomimetic hydrogel microarrays with independently tunable cues is expected to comprise a powerful tool to advance the fundamental understanding of stem cell-niche interactions in 3D, thus addressing a critical problem in stem cell biology and tissue engineering. The outcomes of the proposed research may greatly accelerate stem cell-based therapies by rapidly identifying optimal cues to direct stem cells into maintaining pluripotency or differentiating into functional mature cells. Ongoing and new educational plans target students from kindergarten to undergraduates. An outreach program for local elementary school K-G1 students, called "The Magic of Repairing Human Body," will be developed. The PI will also develop a one-week summer camp for high school students on "Tissue Engineering Fiesta, which will include interactive lectures, journal clubs and hands-on activities and will be geared towards high school students from underprivileged and minority background in the San Francisco Bay Area. Overall, the PI addresses a challenging problem with broader implications and has demonstrated commitment towards educational and outreach activities with local schools with diverse student populations.