Mechanically controlled release of hematopoietic factors from mesenchymal stromal cells for blood regeneration

描述(申请人提供)：造血干细胞(HSC)移植已被用作许多造血疾病和恶性肿瘤的标准治疗方法，以实现许多患者的血液再生。然而，为需要异基因移植的患者获取足够数量的相容的造血干细胞来源仍然具有挑战性，因此只有一小部分患者接受了移植。因此，需要新的进展来开发体外扩增HSCs或在体内再生HSCs的策略。多能骨髓(BM)间充质基质细胞(MSCs)是骨髓中HSC生态位的主要成分，为造血程序提供关键的调节信号。如何利用MSCs仍然是实现血液再生临床益处的重要目标。生物力学领域的进展表明，天然骨髓环境中表现出的一系列基质硬度在骨髓间充质干细胞中引发了深刻的收缩力依赖的生物反应。因此，这项建议的目标是评估具有可调基质硬度的生物材料在控制MSCs以促进血液再生方面的潜力。总体假设是，基质僵硬控制着MSCs蛋白质的分泌，进而以旁分泌的方式影响造血。具体目的包括：(1)阐明骨髓间充质干细胞依赖基质硬度释放造血因子的机制。(2)设计了可注射的水凝胶微滴，可以包裹单个基质硬度可调的MSCs。(3)评价水凝胶微滴中骨髓间充质干细胞在体内对人体血液再生的治疗作用。在K99培训期间，该奖项将用于进一步加强候选人在干细胞机械生物学方面的培训，并使他在生物材料设计和先进微技术的物理方法方面变得称职。这项研究将在哈佛大学的一个主要生物工程实验室进行，该实验室专注于基于生物材料的组织工程技术开发和研究机械转导，与马萨诸塞州总医院有着密切的临床联系。这一经验将确保候选人顺利过渡到R00阶段，成为机械生物学和生物工程之间的独立翻译研究员，开发新的造血疾病治疗策略。

DESCRIPTION (provided by applicant): Project Summary Hematopoietic stem cell (HSC) transplantation has been used as a standard treatment for a number of hematopoietic disorders and malignancies to achieve blood regeneration in many patients. However, procuring a sufficient number of compatible HSC sources for patients who need allogeneic transplantation remains challenging, and thus only a fraction of the patients undergo transplantation. Therefore, new advances are needed to develop strategies to either expand HSCs ex vivo or regenerate HSCs in vivo. Multipotent bone marrow (BM) mesenchymal stromal cells (MSCs) are the major constituents of the HSC niche in the bone marrow, providing key regulatory signals to program hematopoiesis. How MSCs can be harnessed remains an important goal to achieve clinical benefits for blood regeneration. Advances in the field of biomechanics have revealed that a range of matrix stiffness exhibited by the native BM milieu elicits profound contractile force- dependent biological responses in MSCs. The goal of this proposal is thus to evaluate the potential of biomaterials with tunable matrix stiffness for use in controlling MSCs to facilitate blood regeneration. The overall hypothesis is that matrix stiffness controls secretion of proteins from MSCs, and in turn, influences hematopoiesis in a paracrine manner. The specific aims include: (1) Elucidate mechanisms behind matrix stiffness-dependent release of hematopoietic factors from MSCs. (2) Engineer injectable hydrogel microdroplets that can encapsulate single MSCs with tunable matrix stiffness. (3) Assess the therapeutic effect of MSCs in hydrogel microdroplets on human blood regeneration in vivo. During the K99 training period, this award will be used to further the candidate's training in stem cell mechanobiology, and for him to become competent in physical approaches to biomaterial design and advanced microtechnologies. This research will be conducted in a major bioengineering laboratory at Harvard University that focus on biomaterial-based technology development for tissue engineering and studying mechanotransduction, with close clinical connections at Massachusetts General Hospital. This experience will ensure a smooth transition into the R00 phase for the candidate to become an independent translational investigator at the interface between mechanobiology and bioengineering to develop novel therapeutic strategies for hematopoietic disorders.