BIOMECHANICS OF STEM CELLS

这个子项目是利用资源的许多研究子项目之一。 由NIH/NCRR资助的中心拨款提供。对子项目的主要支持 子项目的首席调查员可能是由其他来源提供的， 包括美国国立卫生研究院的其他来源。为子项目列出的总成本可能 表示该子项目使用的中心基础设施的估计数量， 不是由NCRR赠款提供给次级项目或次级项目工作人员的直接资金。 该项目的目的是研究干细胞的机械性能。我们将使用一种新的方法，将实验和有限元模拟相结合，以确定干细胞的机械性能，如杨氏模数和极限强度。这些实验将涉及在施加吸气压力的情况下对干细胞进行微吸管抽吸(MPA)。随后，将使用商业有限元软件ABAQUS对吸气过程进行模拟。我们将尝试用于干细胞的各种候选粘弹性材料模型，如Maxwell模型、广义Maxwell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材料反应的模型(通过MPA实验测量)，以及一组模型参数的最佳值。我们将通过调整有限元模拟中使用的模型来实现这一点，直到模拟的吸气历史(作为时间函数的吸气体积预测)与实验观察到的匹配。为了计算模型参数的种群平均值，将对对应于三个细胞系的一些干细胞进行抽吸实验：CD34细胞(通常用于心脏治疗)、神经干细胞(NSCs)和骨髓基质细胞(MBMSCs)。对于每个实验，都需要进行大量的有限元模拟来微调模型及其参数。因此，需要超级计算资源才能成功执行这一项目。我们建议在这个项目中使用ABAQUS的PSC‘s Pople，因为我们以前有使用ABAQUS的经验，并使用POLE进行CFD和FSI模拟。我们将提供我们自己的Abaqus许可证。此外，ABAQUS的并行执行可以同时使用线程和MPI任务，我们将确定哪种模式在Pople上运行得最好。因此，我们想申请一个启动拨款与30,000苏为这个项目的Pople。这很可能不足以完成这个项目，所以我们打算稍后申请研究拨款。我们也想请求ASTA对这个项目的支持，帮助我们找出在Pople上运行ABAQUS模拟的最有效的方法。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. 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.