Molecular Engineering of Bioactive Hydrogels

描述（由申请人提供）：人胚胎干细胞（hESCs）作为治疗疾病和损伤（如组织工程和重建、糖尿病、帕金森病、白血病、充血性心力衰竭等）的细胞来源具有强大的潜力。将hESC成功整合到此类治疗中将取决于三个关键步骤：它们的扩增而不分化（即自我更新），它们分化为特定的细胞类型或细胞类型的集合，以及促进它们的存活和功能整合到现有组织中。然而，在这些步骤中控制细胞行为需要对细胞微环境进行精确控制。这对目前的hESC体外培养系统提出了重大挑战，这些系统的范围从与饲养细胞共培养到无血清系统，其中细胞在复杂的细胞外基质蛋白上培养。所有这些系统都涉及动物或人类蛋白质，这给病原体传播、免疫排斥、有限的可重复性和扩大到临床过程带来了问题。为了实现再生医学的预期目标，精确控制体外和体内干细胞群的存活、增殖和分化的方法是必要的。在此，我们建议开发一个完全合成的环境来精确控制hESC在文化中的自我更新。具体来说，我们将设计一个可调的和明确定义的环境，呈现一个完全的“合成细胞外基质”（ECM）和化学定义的介质来控制hESCs的自我更新/扩展。此外，我们将

Description (provided by applicant): Human embryonic stem cells (hESCs) have strong potential as sources of cells for the treatment for disease and injury (e.g. tissue engineering and reconstruction, diabetes, Parkinson's Disease, leukemia, congestive heart failure, etc.). The successful integration of hESC into such therapies will hinge upon three critical steps: their expansion without differentiation (i.e., self-renewal), their differentiation into a specific cell type or collection of cell types, and the promotion of their survival and functional integration into existing tissue. However, controlling cell behavior during each of these steps will require precise control over the cellular microenvironment. This poses a major challenge ex vivo in current hESC culture systems, which range from co-culture with feeder cells to serum-free systems where cells are cultured on complex extracellular matrix proteins. All such systems involve animal or human proteins, which pose problems for pathogen transmission, immune rejection, limited reproducibility, and scale up to a clinical process. To achieve the intended goals of regenerative medicine, methods for the precise control of the survival, proliferation, and differentiation of stem cell populations in vitro and in vivo are necessary. Here, we propose to develop a completely synthetic environment to precisely control hESC self-renewal in culture. Specifically, we will engineer a tunable and well-defined environment presenting a completely "synthetic extracellular matrix" (ECM) and chemically-defined media to control the self-renewal/expansion of hESCs. Furthermore, we will develop high throughput approaches to identify synthetic peptide ligands for functionalization to the synthetic ECM and promotion of hESC self-renewal. If hESCs can be derived and maintained within this fully synthetic microenvironment, then it will be possible to eliminate pathogen transmission associated with mouse or human feeder layers, provide a scalable basis for large-scale production of hESCs, and provide a precise base for further development to control hES cell differentiation. Furthermore, the result will be a technology platform that can be generally applied to numerous stem cell populations and used to investigate the basic biological/developmental mechanisms underlying self-renewal. Public Health Relevance: The development of novel, bioactive materials has significant potential for exerting precise control over cell function, both for fundamental biological studies and applications in tissue engineering and regenerative medicine. For example, developing synthetic, bioactive material systems to promote the self-renewal and expansion of human embryonic stem cells will have numerous biomedical applications including the design of therapies for disease or injury in the muscle, bone, brain, heart, liver, pancreas, and other tissues. The novel blend of stem cell biology, materials science, molecular biology, and bioengineering described in this proposal will be well suited to addressing an important problem, i.e. stem cell control, at the interface of biology, engineering, and medicine