Design of an Engineered Cartilage Biocomposite for Joint Rehabilitation

描述（由申请人提供） Bilgen博士是目前的CDA-1接受者（2008年），具有强大的生物工程背景，在软骨组织工程方面拥有10多年的实践研究经验。 Bilgen博士的研究兴趣包括骨科临床问题的生物工程应用，特别是骨骼生物学，修复和再生。 本申请旨在开发一种可移植的生物复合材料，以恢复创伤关节的软骨。年轻退伍军人的肢体创伤通常会导致软骨组织功能丧失，从而导致严重的关节炎和骨关节炎。 2003年，全国关节炎的医疗费用为810亿美元，工资损失为470亿美元。 美国退伍军人面临关节炎的风险增加相比，非退伍军人由于骨科损伤在军队。植入由患者的自体软骨细胞产生的工程化软骨在愈合软骨缺损方面并不完全成功。 本课题主要解决软骨组织工程中存在的两个主要问题：1）成人自体软骨细胞的有限可用性和间充质干细胞（MSC）的有限分化，2）工程化软骨的机械性能不足。 由于有限的软骨细胞可用性，成体间充质干细胞（MSC）被广泛用于产生软骨组织，但它们不以与软骨细胞相同的速率分泌软骨基质。 我们和其他人已经表明，共培养成人干细胞与软骨细胞改善工程软骨的生化组成。 在组织培养过程中应用间歇性机械负荷，如压缩或剪切，已显示可改善软骨形成，但最佳剂量因细胞和组织性质而异。 中心假设是，软骨细胞和MSC的共培养和双轴机械负荷的应用的组合将协同增强细胞外基质（ECM）的沉积，并改善移植后软骨组织的功能特性。在为期五年的CDA-2计划中，Bilgen博士旨在实现三个研究目标：1-开发一种共培养系统，以解决软骨细胞有限的可用性：该方法是使用软骨细胞和滑膜MSC和生长因子的组合来优化ECM沉积。预期的结果是一种新的细胞来源的方法，利用软骨细胞和滑膜MSC的共培养物。2-创建具有改善的机械性能的软骨生物复合材料：我们设计了一种新型的双轴加载装置，该装置在长期体外研究中显示出与组织工程化软骨生物复合材料的开发兼容。本研究旨在探讨体外单轴和双轴力学加载对细胞分化和组织工程化的力学性能的影响。预期的结果是开发一种新型双轴载荷系统，以创建一种可以成功修复和恢复软骨功能的生物复合材料。3-开发一种用于软骨修复的体内相容性生物复合材料：该方法将在体外培养生物复合材料以改善功能特性，然后在小型猪模型的软骨缺损中体内植入。预期的结果是开发一种生物复合材料，可以成功地修复体内软骨。本研究的创新点在于将指导性共培养和新型机械加载方案协同应用于使用间充质干细胞的软骨组织工程系统。更广泛的影响是，开发的技术预计将治疗退行性关节疾病并防止关节置换手术，从而影响近一半的人口。

DESCRIPTION (provided by applicant) Dr. Bilgen is a current CDA-1 recipient (2008) and has a strong bioengineering background with hands-on research experience over 10 years in cartilage tissue engineering. Dr. Bilgen's research interests include bioengineering applications to clinical problems in orthopaedics, specifically skeletal biology, repair and regeneration. This application aims to develop a transplantable biocomposite to restore cartilage of a traumatized joint. Limb trauma in young veterans often results in loss of cartilage tissue function that leads to severe arthritis and osteoarthritis. Total national cost of arthritis was $81 billion in medical costs and $47 billion in lost wages in 2003. US veterans face increased risks of arthritis compared with non-veterans due to orthopedic injuries at the military. Implantation of engineered cartilage that is produced by the patient's autologous chondrocytes is not fully successful in healing cartilage defects. This project addresses two main problems in cartilage tissue engineering: 1) limited availability of adult autologous chondrocytes and limited differentiation of mesenchymal stem cells (MSC), 2) insufficient mechanical properties of engineered cartilage. Due to limited chondrocyte availability, adult mesenchymal stem cells (MSC) are widely used to produce cartilage tissue, but they do not secrete cartilage matrix at the same rate as chondrocytes. We and others have shown that co-culturing adult stem cells with chondrocytes improve the biochemical composition of engineered cartilage. Application of intermittent mechanical loading such as compression or shear during tissue cultivation has been shown to improve cartilage formation, however the optimum dose differs with cell and tissue properties. The central hypothesis is that the combination of co-culturing chondrocytes and MSC and application of biaxial mechanical loading will synergistically enhance deposition of extracellular matrix (ECM) and improve the functional properties of cartilage tissue after transplantation. Over the five-year CDA-2 program, Dr. Bilgen aims to achieve three research goals: 1- Develop a co-culture system to address the limited availability of chondrocytes: The approach is to optimize ECM deposition using a combination of chondrocytes and synovial MSC and growth factors. The expected outcome is a novel cell sourcing methodology that utilizes co-cultures of chondrocytes and synovial MSC. 2- Create a cartilage biocomposite with improved mechanical properties: We designed a novel biaxial loading device, which was shown to be compatible with the development of tissue-engineered cartilage biocomposites in long term in vitro studies. The approach is to investigate the effects of uniaxial and biaxial mechanical loading in vitro on the differentiation of cells and the mechanical properties of engineered tissue. The expected outcome is the development of a novel biaxial loading system to create a biocomposite that can successfully repair and restore function to cartilage. 3- Develop an in vivo-compatible biocomposite for cartilage repair: The approach will be to cultivate the biocomposite in vitro to improve functional properties followed by implantation in vivo in a chondral defect in a minipig model. The expected outcome is the development of a biocomposite that can successfully repair cartilage in vivo. The innovation in this grant proposal lies in the synergistic application of instructive co- culturing and a novel mechanical loading scheme on a cartilage tissue engineering system using mesenchymal stem cells. The broader impact is that the developed techniques are anticipated to treat degenerative joint diseases and prevent joint replacement surgeries, thus impacting nearly half of the population.