Design and Evaluation of Ultrasound Stimulation Aided Bioreactor Configurations

描述（由申请人提供）：关节软骨，覆盖滑膜关节末端的无血管组织，为关节提供持久的重量分布表面，因疾病或创伤而受损，自我修复能力很小。目前的干预措施包括自体或异体移植、关节表面重塑等，但效果有限，从长远来看，未经治疗的病变可能导致大面积退行性改变和骨关节炎。因此，产生组织工程关节软骨的生物反应器和生物工艺策略仍在继续研究，因为替换患病或受损的软骨是一个尚未解决的重要医学问题。我们研究的长期目标是设计和开发可用于产生工程组织的生物反应器或生物处理单元。我们生成组织工程构建策略的一个重要组成部分是使用生物反应器为细胞种子支架提供足够的刺激。本次R21基金申请的目的是开发一种利用超声刺激的生物反应器，并对超声对体外3d支架中培养的软骨细胞的影响进行详细研究。我们会透过以下的具体目标来达成这项申请的目标：

DESCRIPTION (provided by applicant): Articular cartilage, the avascular tissue that covers the ends of synovial joints and provides articulating joints with a durable, weight-distributing surface, damaged by illness or trauma has little capacity for self-repair. Current interventions that include autologous or heterologous transplantation, articular resurfacing, are of limited efficacy, and in the long term, untreated lesions may result in large-scale degenerative changes and osteoarthritis. Hence bioreactor and bioprocess strategies to generate tissue-engineered articular cartilage continue to be researched, as replacement of diseased or damaged cartilage represents an important medical problem that remains unsolved. The long-term goal of our research is to design and develop bioreactors or bioprocessing units that can be used to generate engineered-tissues. An important component of our strategy to generate tissue-engineered constructs is the use of bioreactors to provide adequate stimulus to the cell-seeded scaffolds. Our objective in this R21 grant application is to develop a bioreactor that utilizes stimulation by ultrasound, and conduct a detailed study on the effect of ultrasound on chondrocytes cultured in 3-D scaffolds in vitro. We will achieve the objective of this application by pursuing the following specific aims: Specific aim 1: To develop a bioreactor that uses continuous ultrasound to enhance cartilage matrix formation and maintain chondrocyte differentiation. Specific Aim 2: To implement a feedback loop into the US-based bioreactor. Specific Aim 3: To evaluate the effects of continuous ultrasound on the morphology and cytoskeleton of chondrocytes maintained in the bioreactors under development. Public Health Relevance Statement: At the conclusion of the R21 phase of the proceed research, we expect to have designed and developed a novel US-aided bioreactor configuration that incorporates a feed-back control to provide different regimes of mechanical conditioning to engineered tissues at different stages of development. We propose that the novelty of this strategy lies with the assessment of the cellular response to ultrasound exposure and, the application of this technology to efficiently and effectively grow cells (i.e. chondrocytes) in 3D culture systems. While bioreactors based on rotation and compression are well described, much remains to be learned about bioreactors based on US stimulation. In summary, while US has been shown to impact cartilage function at the cellular level, there is still a need to better understand the effect of US stimulation of chondrocytes seeded and maintained in 3-D scaffolds, which are better representatives of chondrocytes in-vitro culture. At the completion of this research, we expect to: 1) better understand how mechanical stimulation by ultrasound influences cell activity in 3-D scaffolds and 2) better understand the complex interplay between various factors (mechanical and biochemical cues) influencing tissue formation. Finally, we expect to have developed a highly reproducible in vitro model system of chondrocyte 3D-culture that likely uses US, which will allow us to carry out a detailed examination of the mechanisms of signal transduction processes in a future R-01 application.