CAREER: Biomaterial-mediated control over macrophage activation

非技术性炎症，以及我们控制它的能力，是现代医学的中心主题。植入生物材料的成功与否尤其取决于巨噬细胞的行为，巨噬细胞是先天免疫系统的原代细胞，它决定了生物材料是成功地与身体结合还是被排斥。因此，需要一种多功能的生物材料修饰策略来精确控制浸润巨噬细胞的行为，以适应不同的应用。蛋白质-配体结合对生物素和亲和素以其特殊的强度而闻名。然而，最近发现，当生物素附着在蛋白质和药物等大分子上时，这种结合强度会降低，导致结合断裂，蛋白质被释放，从而对浸润免疫细胞的行为产生影响。通过修改制备参数，可以在很大范围内调节蛋白质释放的速率，并且可以选择所选的蛋白质来精确地操纵巨噬细胞的行为，允许生物材料设计者为每个预期的应用调整免疫系统。当该系统被纳入生物材料的三维环境中时，键断裂和蛋白质从生物材料中扩散的速率可能取决于生物材料环境，包括生物材料本身及其周围环境，但这些现象从未被探索过。因此，在本项目中，将彻底表征生物材料的微观结构和密度等特性的影响，以及动态生物素-亲和素结合系统如何改变这些特性，以推进结合系统与生物材料之间相互作用的基础知识。此外，将评估外部生物材料微环境的影响，包括免疫细胞和血管的浸润，这是所有植入生物材料不可避免的结果。该项目的结果将为生物医学应用中调节免疫系统的生物材料的设计铺平道路，同时有助于对基础生物学、生物传感器和纳米技术应用中三维结合相互作用的基本理解。此外，该项目整合了Drexel工程学生的教育计划，并与早期儿童教育工作者合作，在费城学校的学生从幼儿园到三年级的过程中反复向他们介绍生物材料工程原理。该计划的主要目标是：1)试点教育活动，以发展为课程单元，与其他教师分享；2)提高德雷克塞尔学生的指导技能。这个项目的第二个目标是收集项目有效性的初步数据，以提高学生的STEM成绩。植入生物材料的成功取决于巨噬细胞的行为，巨噬细胞是先天免疫系统的原代细胞，它决定了生物材料是被包裹在纤维囊中，还是血管化并与周围组织结合。因此，需要一种多功能的生物材料修饰策略来精确控制浸润性巨噬细胞的表型，以适应不同的应用。该项目的目标是确定亲和结合相互作用和生物材料微环境的变化如何影响生物材料释放细胞因子以调节巨噬细胞的行为。生物素和亲和素的亲和结合对将被用来确定生物素与蛋白质等大分子结合后解离动力学是如何改变的，从而导致生物材料的受控释放，这是生物素-亲和素技术的新应用，从未被探索过。生物偶联参数（如生物素价和间隔臂长度）以及生物材料特性（如交联密度和空间分布）对巨噬细胞调节因子释放的影响将在体外确定。将探索结合生物材料的时空控制设计策略，包括3D生物打印和多种蛋白质的顺序释放。最后，将通过体外和体内实验的结合，研究与体内微环境（如内源性生物素的存在、浸润巨噬细胞的数量和生物材料血管化）相互作用对细胞因子释放的影响。这些结果也将为生物材料介导的巨噬细胞行为控制如何影响生物材料血管化提供初步数据。此外，该项目整合了Drexel工程学生的教育计划，并与早期儿童教育工作者合作，在费城学校的学生从幼儿园到三年级的过程中反复向他们介绍生物材料工程原理。该计划的主要目标是：1)试点教育活动，以发展为课程单元，与其他教师分享；2)提高德雷克塞尔学生的指导技能。这个项目的第二个目标是收集项目有效性的初步数据，以提高学生的STEM成绩。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。

Non-technical Inflammation, and our ability to control it, is a central theme in modern medicine. The success of implanted biomaterials in particular hinges on the behavior of macrophages, the primary cells of the innate immune system that dictate whether a biomaterial will be successfully integrated with the body or will be rejected. Thus, there is a need for a versatile biomaterial modification strategy to precisely control the behavior of infiltrating macrophages for different applications. The protein-ligand binding pair biotin and avidin is known for its exceptional strength. However, it was recently discovered that this binding strength decreases when biotin is attached to larger molecules like proteins and drugs, causing the bond to break and the protein to be released, with resultant effects on the behavior of infiltrating immune cells. The rate of protein release can be tuned over a wide range by modifying preparation parameters, and the selected protein can be chosen to precisely manipulate macrophage behavior, allowing the biomaterials designer to tune the immune system for each intended application. When this system is incorporated into the three-dimensional environment of a biomaterial, the rate that the bond breaks and the protein diffuses from the biomaterial likely depends on the biomaterial environment, including the biomaterial itself and its surrounding milieu, but these phenomena have never been explored. Thus, in this project the effects of biomaterial properties like microstructure and density, and how these properties are changed by the inclusion of the dynamic biotin-avidin-binding system, will be thoroughly characterized, in order to advance fundamental knowledge of the interactions between the binding system and biomaterials. In addition, the effects of the external biomaterial microenvironment will be assessed, including the infiltration of immune cells and blood vessels, an inevitable outcome for all implanted biomaterials. The results of this project will pave the way for the design of biomaterials that can modulate the immune system for biomedical applications, while contributing fundamental understanding of binding interactions in three dimensions with applications in basic biology, biosensors, and nanotechnology. In addition, this project integrates an educational program with Drexel engineering students in collaboration with early childhood educators to repeatedly introduce Philadelphia school students to biomaterials engineering principles as they progress from kindergarten to grade 3. The major goals of this program are to: 1) pilot educational activities for development as curriculum units to share with other teachers, and 2) improve mentorship skills of Drexel students. A secondary goal of this program is to collect preliminary data on the effectiveness of the program to improve students' STEM performance.Technical The success of implanted biomaterials hinges on the behavior of macrophages, the primary cells of the innate immune system that dictate whether a biomaterial will be encapsulated in a fibrous capsule or vascularized and integrated with the surrounding tissue. Thus, there is a need for a versatile biomaterial modification strategy to precisely control the phenotype of infiltrating macrophages for different applications. The goal of this project is to determine how changes in affinity binding interactions and the biomaterial microenvironment affect the release of cytokines from biomaterials to modulate macrophage behavior. The affinity binding pair biotin and avidin will be utilized to identify how dissociation kinetics are altered upon conjugation of biotin to larger molecules like proteins to result in controlled release from biomaterials, a new application of biotin-avidin technology that has never been explored. The effects of bioconjugation parameters like biotin valency and the length of the spacer arm as well as biomaterial properties like crosslinking density and spatial distribution on release of macrophage-modulating cytokines will be determined in vitro. Combination with biomaterials design strategies for spatiotemporal control will be explored, including 3D bioprinting and the sequential release of multiple proteins. Finally, the effects of interactions with the in vivo microenvironment, such as the presence of endogenous biotin, number of infiltrating macrophages, and biomaterial vascularization, on cytokine release will be investigated using a combination of in vitro and in vivo experiments. These results will also contribute preliminary data on how biomaterial-mediated control over macrophage behavior affects biomaterial vascularization. In addition, this project integrates an educational program with Drexel engineering students in collaboration with early childhood educators to repeatedly introduce Philadelphia school students to biomaterials engineering principles as they progress from kindergarten to grade 3. The major goals of this program are to: 1) pilot educational activities for development as curriculum units to share with other teachers, and 2) improve mentorship skills of Drexel students. A secondary goal of this program is to collect preliminary data on the effectiveness of the program to improve students' STEM performance.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.