Chondrocyte mechanotransduction and the purinergic receptor pathway

提出的研究计划的总体目标是研究软骨细胞对机械负荷的反应中的嘌呤能途径。将机械载荷应用于组织工程软骨构建体是一种被广泛应用的加速组织生长和提高组织力学性能的方法。然而，使用机械刺激来产生这种效果有两个主要缺点：(i)由于细胞对刺激迅速脱敏，施加载荷的可用窗口有限；（ii）将机械刺激应用于组织结构需要使用复杂的设备和高度的操作人员培训。最近，已经确定软骨细胞在机械转导过程中利用三磷酸腺苷（ATP）作为信号分子。机械负荷引起ATP的释放，从而刺激其他细胞合成组织。这一途径（嘌呤能受体途径）受到严格调控，因为这些细胞也表达降解ATP的酶，从而使细胞对施加的机械刺激脱敏。研究嘌呤能受体途径在软骨细胞机械转导过程中的作用的拟议研究计划将在两个项目中进行：(i)嘌呤能受体途径参与细胞对机械负荷的脱敏，(i)通过外源性ATP直接利用嘌呤能受体途径。这项研究将进一步加深我们对机械转导过程的了解，这些过程直接应用于以机械负荷反应受损为特征的疾病状态（例如骨关节炎）。此外，这项研究将促进功能性工程组织的发展，帮助为患有严重关节炎疾病的患者创造新的治疗选择。在未来五年内，该研究计划将为生物医学工程专业的职业生涯培养7名HQPs（2名博士，5名本科生）。参与这些项目的HQPs将有机会参与跨学科研究，并获得组织工程和再生医学领域的基础知识和实践经验。

The overall goal of the proposed research program is to investigate the purinergic pathway in the response of cartilage cells to mechanical loading. The application of mechanical loading to tissue engineered cartilage constructs is a widely used method to accelerate tissue growth and enhance tissue mechanical properties. However, there are two major drawbacks with the use of mechanical stimuli to elicit such effects: (i) the available window to apply loading is limited as the cells rapidly desensitize to the stimulus, and (ii) the application of mechanical stimuli to tissue constructs requires the use of complex equipment and a high degree of operator training. Recently, it has been identified that cartilage cells utilize adenosine triphosphate (ATP) as a signalling molecule in the mechanotransduction process. Mechanical loading elicits the release of ATP which stimulate other cells to synthesize tissue. This pathway (purinergic receptor pathway) is tightly regulated as these cells also express enzymes which degrade ATP, thereby desensitizing the cells to the imposed mechanical stimulus. The proposed research program to investigate the involvement of the purinergic receptor pathway during chondrocyte mechanotransduction will be carried out in two projects: (i) purinergic receptor pathway involvement in cellular desensitization to mechanical load, and (i) directly harnessing the purinergic receptor pathway through exogenous ATP. This research will further our knowledge of mechanotransduction processes which have direct applications to disease states (e.g. osteoarthritis) that are characterized by an impaired response to mechanical loading. In addition, this research will facilitate the development of functional engineered tissues to help create of new treatment options for patients suffering from severe arthritic disorders. Over the next five years, this research program will prepare 7 HQPs (2 PhD; 5 undergraduate) for professional careers in biomedical engineering. HQPs working on these projects will have the opportunity to be involved in inter-disciplinary research and to acquire fundamental knowledge and practical experience in the area of tissue engineering and regenerative medicine.