BIOMECHANICS OF STEM CELLS

该子项目是利用 由NIH/NCRR资助的中心赠款提供的资源。子项目和 研究者（PI）可能从另一个NIH来源获得主要资金， 因此可以在其他CRISP条目中表示。列出的机构是 中心，不一定是研究者的机构。 本项目的目的是研究干细胞的力学性能。我们将使用一种新的方法，将实验与有限元模拟相结合，以确定干细胞的力学性能，如杨氏模量和极限强度。实验将涉及在施加的抽吸压力下对干细胞的微量移液管抽吸（MPA）。随后，将使用商业有限元软件ABAQUS模拟抽吸过程。我们将尝试用于干细胞的各种候选粘弹性材料模型，例如麦克斯韦模型、广义麦克斯韦模型、Kelvin-Voigt模型或标准线性固体（SLS）模型。我们的目标是找到最接近干细胞的材料响应的模型（通过MPA实验测量），以及一组模型参数的最佳值。我们将通过调整FEM模拟中使用的模型来实现这一点，直到模拟的抽吸历史（抽吸体积投影作为时间的函数）与实验观察到的相匹配。为了计算模型参数的群体平均值，将对对应于三种细胞系的许多干细胞进行抽吸实验：CD 34+细胞（通常用于心脏治疗）、神经干细胞（NSC）和骨髓基质细胞（mBMSC）。对于每个实验，需要执行大量的FEM模拟以微调模型及其参数。因此，需要超级计算资源来成功执行这个项目。我们建议在PSC的Pople上使用ABAQUS进行本项目，因为我们有使用ABAQUS和使用Pople进行CFD和FSI模拟的经验。我们将提供自己的ABAQUS许可证。此外，ABAQUS的并行执行可以使用线程和MPI任务，我们将确定哪种模式在Pople上最有效。因此，我们想为这个项目申请一笔30,000 SU的启动资金。这很可能不足以完成项目，因此我们打算稍后申请研究拨款。我们也想请求ASTA支持这个项目，帮助找出最有效的方式来运行我们的ABAQUS模拟Pople。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The aim of this project is to investigate the mechanical properties of stem cells. We shall use a novel approach that combines experiments with FEM simulations to identify mechanical properties of stem cells such as the Young's modulus and ultimate strength. The experiments will involve micropipette aspiration (MPA) of stem cells under an applied suction pressure. Subsequently, the aspiration process will be simulated using the commercial FEM software ABAQUS. We shall try various candidate viscoelastic material models for the stem cells, such as the Maxwell model, Generalized Maxwell model, Kelvin-Voigt model or Standard Linear Solid (SLS) model. The goal is to find the model that best approximates the material response of stem cells (as measured experimentally via MPA), together with a set of optimum values for the model parameters. We shall achieve this by tuning the model used in the FEM simulations until the simulated aspiration history (aspirated volume projection as a function of time) matches that experimentally observed. To compute population means of the model parameters, aspiration experiments will be performed on a number of stem cells corresponding to three cell lines: CD34+ cells (generally used for cardiac therapy), neural stem cells (NSCs) and bone marrow stromal cells (mBMSCs). For each experiment, a large number of FEM simulations need to be performed to fine tune the model and its parameters. Hence the need for supercomputing resources for the successful execution of this project. We propose to use ABAQUS on PSC's Pople for this project, as we have prior experience with ABAQUS and using Pople for CFD and FSI simulations. We shall provide our own ABAQUS license. Furthermore, the parallel execution of ABAQUS can use both threads and MPI tasks, and we shall determine which mode works best on Pople. Thus, we would like to request a startup grant on Pople with 30,000 SUs for this project. This will most likely be insufficient for completing the project and so we intend to apply for a research allocation later. We would also like to request ASTA support for this project, for help in figuring out the most efficient way to run our ABAQUS simulations on Pople.