Magnetic Resonance Studies Of Cells, Organs And Animals

细胞、器官和动物的磁共振研究

• 批准号: 7132256
• 负责人: RICHARD SPENCER
• 金额: --
• 依托单位: NATIONAL INSTITUTE ON AGING
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/7132256
• 关键词: articular cartilage; bioimaging /biomedical imaging; biomedical equipment development; bioreactors; chondrocytes; magnetic resonance imaging; musculoskeletal imaging /visualization /scanning

A Bioreactor System for Magnetic Resonance Microimaging and Spectroscopy of Chondrocytes and Tissue Repair of articular cartilage secondary to either traumatic injury or degenerative joint disease represents an important therapeutic challenge. In spite of significant progress in understanding the pathogenesis of this highly prevalent disease, there are no well-accepted disease-modifying interventions. The development of a flexible and reliable MRI-compatible cartilage hollow fiber bioreactor (HFBR) system for neocartilage growth has the potential to contribute to therapeutic approaches. First, conditions promoting the development of high-quality cartilage from cells can be studied intensively in such a system, which provides full control over exposure of the developing neocartilage to growth factors, substrate composition, dissolved O2 and CO2 concentrations, temperature, and other environmental factors. While in situ development of cartilage from cells, including both chondrocytes and, potentially, bone marrow stromal cells, in an organism will differ in important ways from the bioreactor conditions, in vitro studies will be able to point the way to appropriate conditions for development of functioning neocartilage from cells. Second, growth of high-quality cartilage in the bioreactor may result in a source of tissue for actual transplantation. Finally, and most generally, regardless of the specifics of eventual cartilage repair and regeneration procedures, the ability to monitor tissue quality will be of clear importance. While arthroscopic biopsies provide such data, permitting assessment of the biochemical and histologic state of the tissue, it is clearly more desirable to utilize noninvasive assessment methods. MRI is becoming increasingly accepted as a noninvasive tool for the measurement of cartilage thickness and volume and of localized pathology while the ability of MRI to noninvasively assess cartilage quality is currently a topic of active research. The availability of a highly controllable system for generating cartilage with widely varying properties in a system permitting detailed MRI assessment would represent a clear advance in this effort. Finally, we note that the MRI-compatible bioreactor provides a flexible test-bed for current and future therapeutic agents and interventions. In summary, as a cellular system, the HFBR shares with other 3D culture systems the ability to support the hyaline cartilage type. Thus, one can evaluate the effect of growth conditions and therapeutics on hyaline cartilage tissue rather than fibrocartilage. As a tissue system, the HFBR permits true macroscopic growth. Thus, cell-matrix interactions and the effects of the matrix barrier to substrate delivery and metabolic product efflux are represented much more realistically than in monolayer systems. Finally, as a test bed for growth conditions and agents, the HFBR provides full control of substrate and perfusion conditions. We have successfully demonstrated that cartilage grown from chick sternal cells in the HFBR will develop and maintain the hyaline phenotype; that morphologic measurements with MRI correlate with tissue histology; and that MRI measurements of local T1, T2, diffusion and MT correlate with biochemical assays of collagen, proteoglycans and hydration. Thus, noninvasive MRI measures provide reliable information about cartilage matrix composition. We have further demonstrated that cartilage growth in the HFBR can be modified by introduction of biologically active compounds, and that the correlations between MRI-derived parameters and biochemical results noted above are maintained in spite of the greater dynamic range of tissue characteristics resulting from these interventions. We have also utilized 31P NMR measurements of pH, inorganic phosphate (Pi) and ATP to demonstrate that the developing cartilage in the bioreactor remains metabolically stable over the typical 4 week growth period. A major focus of our work has, in addition, been to demonstrate that MRI measurements of matrix fixed density correlate with measurements of dynamic and equilibrium compressive moduli. The MRI-derived FCD values correlate with S-GAG content but not with collagen content. These correlations were found to persist even in tissue which has undergone development in the presence of chondroitinase, acting as a catabolic agent on matrix proteoglycans. Noninvasive MRI evaluation of FCD therefore has been shown to provide reliable information about cartilage matrix composition under the dynamic conditions of the HFBR in both control tissue and in tissue which has undergone degeneration analogous to that seen in osteoarthritis.

用于软骨细胞和组织磁共振显微成像和光谱的生物反应器系统 继发于创伤性损伤或退行性关节疾病的关节软骨修复是一个重要的治疗挑战。尽管在了解这种高度流行疾病的发病机制方面取得了重大进展，但还没有公认的疾病改善干预措施。开发一种灵活可靠的MRI兼容的软骨中空纤维生物反应器（HFBR）系统，用于新软骨生长，有可能有助于治疗方法。首先，可以在这样的系统中深入研究促进从细胞发育高质量软骨的条件，该系统提供了对发育中的新软骨暴露于生长因子、基质组成、溶解的O2和CO2浓度、温度和其他环境因素的完全控制。虽然在生物体中从细胞（包括软骨细胞和潜在的骨髓基质细胞）原位发育软骨在重要方面与生物反应器条件不同，但体外研究将能够指出从细胞发育功能性新软骨的适当条件。第二，生物反应器中高质量软骨的生长可能导致用于实际移植的组织来源。最后，也是最普遍的，不管最终软骨修复和再生过程的具体细节如何，监测组织质量的能力将是非常重要的。虽然关节镜活检提供了这样的数据，允许评估组织的生化和组织学状态，但显然更希望利用非侵入性评估方法。MRI作为测量软骨厚度和体积以及局部病理学的非侵入性工具正变得越来越被接受，而MRI非侵入性评估软骨质量的能力目前是活跃研究的主题。在允许详细MRI评估的系统中产生具有广泛不同性质的软骨的高度可控系统的可用性将代表这一努力的明显进展。最后，我们注意到，MRI兼容的生物反应器为当前和未来的治疗剂和干预提供了一个灵活的测试平台。总之，作为细胞系统，HFBR与其他3D培养系统共享支持透明软骨类型的能力。因此，可以评价生长条件和治疗对透明软骨组织而不是纤维软骨的影响。作为组织系统，HFBR允许真正的宏观生长。因此，细胞-基质相互作用和基质屏障对底物递送和代谢产物外排的影响比单层系统更现实。最后，作为生长条件和试剂的测试床，HFBR提供对基质和灌注条件的完全控制。 我们已经成功地证明，从鸡胸骨细胞在HFBR中生长的软骨将开发和保持透明表型;与MRI的形态学测量与组织组织学相关;和MRI测量的局部T1，T2，扩散和MT与胶原蛋白，蛋白多糖和水化的生化测定相关。因此，非侵入性MRI测量提供有关软骨基质组成的可靠信息。我们进一步证明，HFBR中的软骨生长可以通过引入生物活性化合物来改变，并且尽管这些干预导致组织特征的动态范围更大，但上述MRI衍生参数和生化结果之间的相关性仍得以维持。我们还利用pH、无机磷酸盐（Pi）和ATP的31 P NMR测量来证明生物反应器中发育的软骨在典型的4周生长期内保持代谢稳定。此外，我们工作的一个主要重点是证明MRI测量的矩阵固定密度与测量的动态和平衡压缩模量。MRI衍生的FCD值与S-GAG含量相关，但与胶原含量无关。发现这些相关性甚至在软骨素酶存在下经历发育的组织中也持续存在，软骨素酶作为基质蛋白聚糖的分解代谢剂。因此，FCD的非侵入性MRI评价已被证明在HFBR的动态条件下在对照组织和经历类似于骨关节炎中所见的退化的组织中提供关于软骨基质组成的可靠信息。