Stem Cell-laden Hyaluronic Acid Gels for Cartilage Repair: In Vivo Translation

描述（由申请人提供）：关节软骨损伤的内在修复不令人满意，主要是由于其无血管性和苛刻的物理环境。各种重建技术尚未成功地恢复关节软骨的复杂机械性能。组织工程方法已经在实验室环境中进行，结果与天然组织相当。然而，在体外和体内的daa表明，增加组织成熟度可能会限制与软骨外植体整合的能力。因此，这些数据表明，植入后结构成熟度的“静态”测量（例如压缩模量）可能不是体内成功的最佳指标。或者，体外这些特性的时间依赖性增加（即阳性成熟率）可能提供体内成功的更好指标。因此，本申请的总体目标是采用“基于免疫学”的方法进行软骨组织工程，以确定体外培养参数对组织工程构建体体内性能的重要性。为了实现这一目标，PI将在一个独特的导师团队下进行培训，并将利用一种成功的组织工程方法，使用一种新型水凝胶与成人间充质干细胞（MSC）相结合。一旦优化，这种方法将在大型动物模型中实施。使用该模型系统，我们将1）优化由猪MSC接种的HA水凝胶制成的构建体的体外形成和成熟以建立基线成熟轨迹，2）比较加速构建体体外成熟的机制（增加轨迹），和3）使用体外和体内模型评估成熟轨迹对构建体性质和与周围软骨整合的作用。分析将包括结构成熟的细胞、组织学、生物化学和生物力学测量。该项目的成功完成将代表着损伤后软骨修复的显著进展，并将为影响数百万人的衰弱状况提供一种新的治疗策略。这代表了从软骨TE构建体的金标准基准（即，与天然组织相似的性质）的范式转变。相反，我们专注于“启动”的结构，然后让他们适当地重塑和整合在体内恢复正常功能。此外，所获得的独特经验将极大地有利于PI在骨科研究领域的蓬勃发展，重点关注组织工程的转化模型。

DESCRIPTION (provided by applicant): Intrinsic repair of articular cartilage damage is unsatisfactory, largely due to its avascular nature and demanding physical environment. Various reconstructive techniques have not yet succeeded in restoring the complex mechanical properties of articular cartilage. Tissue engineering approaches have been pursued in the laboratory setting with results on the order of the native tissue. However, in vitro and in vivo daa suggest that increased tissue maturity may limit the ability to integrate with cartilage explants. Thus, these data indicate that "static" measures of construct maturity upon implantation (e.g. compressive modulus) may not be the best indicators of in vivo success. Alternatively, time-dependent increases in these properties in vitro (i.e. positive maturation rates) may provide a better indicator of success in vivo. Thus, the overall goal of this application is to take a "trajectory-based" approach to cartilage tissue engineering to determine the importance of in vitro culture parameters on the performance of tissue engineered constructs in vivo. To accomplish this objective, the PI will train under a unique team of mentors and will utilize a successful tissue engineering approach using a novel hydrogel combined with adult mesenchymal stem cells (MSCs). Once optimized, this approach will be implemented in a large animal model. Using this model system, we will 1) optimize in vitro formation and maturation of constructs made from porcine MSC- seeded HA hydrogels to establish baseline maturation trajectories, 2) compare mechanisms to accelerate construct maturation in vitro (increase trajectories), and 3) evaluate the role of maturation trajectories on construct properties and integration to the surrounding cartilage using both in vitro and in vivo models. Analysis will include cellular, histological, biochemical, and biomechanical measures of construct maturation. Successful completion of this project will represent a marked advance in the restoration of cartilage after injury, and will provide a novel treatment strategy for a debilitating condition affecting millions of people. This represents a shift in the paradigm away from the gold standard benchmark of cartilage TE constructs (i.e. properties similar to native tissue). Instead, we focus on "priming" the constructs, and then allowing them to appropriately remodel and integrate in vivo to restore normal function. Moreover, the unique experience gained will greatly benefit the PI's burgeoning career in orthopaedic research with a strong focus on translational models for tissue engineering.