CAREER: Tissue engineering hematopoietic trabecular bone marrow

职业：组织工程造血小梁骨髓

• 批准号: 1944188
• 负责人: Jungwoo Lee
• 金额: $ 54.97万
• 依托单位: University of Massachusetts Amherst
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-03-01 至 2025-02-28
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1944188&HistoricalAwards=false
• 关键词: CAREER; Tissue; engineering; hematopoietic; trabecular

Every day, the human body’s pool of adult stem cells, termed hematopoietic stem cells (HSCs), develop into nearly one trillion mature blood cells, including red blood cells, white blood cells, platelets and immune cells. These blood cell-forming HSCs primarily reside in trabecular bone marrow (TBM), which is the tissue in the porous end of long bones such as femurs. HSC transplantation is the most successful stem cell therapy, but its clinical impact has been limited by the availability of HSCs. HSC’s are difficult to grow outside the body where they tend to change (differentiate) and lose their ability to develop into any blood cell type. To address the need for a scalable method to grow HSCs without allowing differentiation, the goal of this CAREER project is to develop biomaterial models that mimic the microenvironments of TBM for HSC growth and maintenance. Once developed, the biomaterial models will be combined and integrated into a TBM model in bioreactor designed to growth HSCs. Successful TBM models will advance understanding of bone remodeling associated with aging and the progression of diseases such as osteoporosis and bone cancers, and they may also serve as an alternative to animals during preclinical drug testing. Furthermore, the project will be used to recruit and educate students with diverse backgrounds to face emerging challenges at the intersection between engineering and medicine. Activities include an integrated lecture and lab curriculum for a tissue engineering course, an interdisciplinary team-based (engineering and biology) capstone projects for undergraduate students, and a summer research program for high school girls aligned with the existing Engineering the Cell program.The investigator’s long-term research goals are to deliver translational bioengineered solutions that can advance our understanding of the trabecular bone marrow (TBM) in health and disease and harness the regenerative potential of the TBM. Toward this goal, the aim of this CAREER project is to elucidate the dynamic structure-function relationship that maintains hematopoietic activity in the TBM and to apply this knowledge to design a scalable bioreactor for expanding hematopoietic stem cells (HSCs). Two observations, (1) that blood-forming HSCs primarily reside and function in cavities that maintain comparable bone thickness and cavity diameters while undergoing constant bone remodeling and (2) that aging-associated decrease in trabecular bone thickness and increase in cavity diameters are related to a decrease in hematopoietic activity, suggest a possible relationship between anatomy and function that maintains hematopoietic activity in the TBM. Thus, the project’s central hypothesis is that there exist optimal dimensions and spatial arrangement that effectively coordinate bidirectional crosstalk between the endosteal and vascular niches, which are the two important anatomical and functional niches in the TBM. The project builds on the investigator’s development of (1) inverted colloidal crystal (ICC) hydrogel scaffolds that closely emulate anatomical and physical features of the vascular niche and (2) demineralized bone paper that preserves intact biochemical and structural aspects of the endosteal niche and exhibits biological significance in reproducing the surface and subsurface bone tissue complexity of bone, including osteocytes. The Research Plan is organized under four Objectives: (1) To develop an endosteal niche model that recapitulates bone remodeling-related HSC biology by refining an endosteal niche model in which osteocytes buried in layers of demineralized bone paper under mechanoculture re-create physiological aspects of bone surface and subsurface; (2) To develop a vascular niche model that emulates vascular perfusion-related HSC biology by refining the model of the vascular niche to mimic molecular gradients under perfusion within a microfluidic hydrogel scaffold that supports culture of bone marrow stromal cells (BMSCs); (3) To combine the endosteal and vascular niche models into an integrated TBM model by integrating individually optimized models into a single platform to re-create the differentiation-suppressing quality of the endosteal niche and the proliferation-stimulating quality of the vascular niche and (4) To assemble multiple TBM models into a scalable bioreactor that will maintain a stable level of molecular and mechanical interactions between the endosteal and vascular niches to support the expansion phase of HSCs. To determine the competitive advantages and weaknesses of the ex vivo HSC expansion bioreactor compared to other solutions, a limiting dilution assay will be conducted to determine the in vivo repopulating potential of the culture-expanded HSCs by intravenous injection into sublethally irradiated mice.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.

每天，人体的成体干细胞池，称为造血干细胞（HSC），发育成近一万亿个成熟血细胞，包括红细胞，白色血细胞，血小板和免疫细胞。这些形成血细胞的HSC主要存在于小梁骨髓（TBM）中，小梁骨髓是长骨（例如股骨）的多孔端中的组织。造血干细胞移植是最成功的干细胞疗法，但其临床效果受到造血干细胞可用性的限制。 造血干细胞很难在体外生长，在体外它们往往会发生变化（分化）并失去发育成任何血细胞类型的能力。为了解决对可扩展方法的需求，以在不允许分化的情况下生长HSC，该CAREER项目的目标是开发模拟用于HSC生长和维持的TBM微环境的生物材料模型。一旦开发出来，生物材料模型将被组合并整合到设计用于生长HSC的生物反应器中的TBM模型中。 成功的TBM模型将促进对与衰老相关的骨重建以及骨质疏松症和骨癌等疾病进展的理解，并且它们也可以在临床前药物测试期间作为动物的替代品。 此外，该项目将用于招募和教育具有不同背景的学生，以应对工程和医学交叉领域的新挑战。活动包括组织工程课程的综合讲座和实验室课程，（工程学和生物学）本科生的顶点项目，以及一个针对高中女生的暑期研究项目，该项目与现有的细胞工程项目保持一致。研究者的长期研究目标是提供翻译生物工程解决方案，以促进我们对小梁骨髓（TBM）的理解。在健康和疾病方面发挥作用，并利用隧道掘进机的再生潜力。 为了实现这一目标，该CAREER项目的目的是阐明维持TBM中造血活性的动态结构-功能关系，并应用这些知识设计用于扩增造血干细胞（HSC）的可扩展生物反应器。 两个观察结果，（1）造血HSC主要存在于空腔中并在空腔中发挥作用，这些空腔在经历恒定的骨重建的同时保持相当的骨厚度和空腔直径，以及（2）与年龄相关的骨小梁厚度的减少和空腔直径的增加与造血活性的降低有关，这表明解剖结构和功能之间可能存在关系，维持了TBM中的造血活性。 因此，该项目的中心假设是，存在有效协调骨内膜和血管龛之间的双向串扰的最佳尺寸和空间布置，这是TBM中两个重要的解剖和功能龛。该项目建立在研究者开发的（1）倒置胶体晶体（ICC）水凝胶支架，其紧密模仿血管龛的解剖和物理特征，以及（2）脱矿骨纸，其保留了骨内膜龛的完整生物化学和结构方面，并在再现骨的表面和亚表面骨组织复杂性（包括骨细胞）方面具有生物学意义。研究计划分为四个目标：（1）通过完善骨内生态位模型，建立一个骨内生态位模型，重现骨重建相关的HSC生物学，在该模型中，骨细胞在机械培养下被埋在脱矿骨纸层中，重建骨表面和亚表面的生理方面;（2）建立一个模拟血管灌注的血管生态位模型-通过改进血管生态位模型以模拟微流体水凝胶支架内灌注下的分子梯度，支持骨髓基质细胞（BMSC）的培养;（3）通过将单独优化的模型集成到单个平台中，将骨内膜和血管生态位模型联合收割机组合到集成的TBM模型中，以重建骨内膜生态位的分化抑制质量和血管生态位的增殖刺激质量，以及（4）将多个TBM模型组装到可扩展的生物反应器中，该生物反应器将保持骨内膜和血管龛之间稳定的分子和机械相互作用水平，以支持HSC的扩增阶段。 为了确定离体HSC扩增生物反应器与其他解决方案相比的竞争优势和弱点，将进行有限稀释测定以确定培养物的体内再增殖潜力。该奖项反映了NSF的法定使命，并被认为值得通过使用基金会的智力价值和更广泛的影响审查进行评估来支持的搜索.