Optical Molecular Tomography for Regenerative Medicine

描述（由申请人提供）：最重要的医疗挑战包括心血管疾病、中风、退行性神经系统疾病、糖尿病、关节炎、骨质疏松症、肾和肝功能衰竭、脊髓损伤、烧伤、战场创伤和其他破坏性疾病。器官移植解决了其中一些需求，但供体的稀缺和免疫抑制的风险对移植造成了重大限制。再生医学旨在为数百万无法接受移植的患者设计修复或替换受损组织和器官的新方法。一项核心技术是通过将活细胞接种到可生物降解的支架上，然后通过外科手术将构建体植入患者体内，从而对功能性组织或器官进行生物工程改造。组织工程涉及细胞和支架的广泛重塑。进展的一个主要障碍是无法实时监测这种动态复杂的生物过程，这使得控制和优化非常困难。另一方面，正如NIH路线图中所定义的，分子成像在医学进步中发挥着越来越重要的作用。光学分子成像工具现在可以更好地了解几乎所有人类疾病的小鼠模型中分子和细胞水平的生物相互作用，并发现了几个主要的临床应用。因此，我们有动力将生物医学研究中的这两项前沿技术-组织工程和光学分子成像-整合到一个统一的框架中，并推动从活检组织或2D培养模型中的细胞功能静态分析向3D系统的系统分析的范式转变。 该项目的总体目标是开发一种用于再生医学的首个多探针多模态光学分子断层扫描系统，并证明其在植入前和植入后阶段评估生物工程血管的实用性。荧光探针将用于标记管状支架和血管的两种主要细胞类型（内衬管腔的内皮细胞和壁中的平滑肌细胞）。嵌入支架内的光纤将为光学相干断层扫描提供激光并激发荧光探针。将开发创新算法来重建多个荧光探针的3D分布。所提出的成像系统将首先用于在模拟血流条件的生物反应器中以100 μ m的分辨率跟踪生物工程血管的发展。 额外的荧光探针将用于监测细胞特异性基因表达，并验证工程化血管内细胞的生理反应。然后将血管作为插入移植物植入活羊的颈动脉中，并以500 μ m分辨率成像，以跟踪组织再生和功能。该项目的成功完成将创建新的光学分子成像工具，并在血管工程中得到证明，并对再生医学的许多其他领域产生重大而持久的影响。 公共卫生相关性：再生医学通过将自身细胞接种到可生物降解的支架上，并通过外科手术将其植入患者体内，从而创造出器官或组织。本项目将以生物工程血管为例，开发一种先进的光学成像系统，用于在实验室和活体动物中观察、分析和优化组织再生的复杂过程。这些结果将使数千万患有严重血管或神经系统、心脏、肾脏、肝脏、骨骼、膀胱或其他器官受损的患者受益。

DESCRIPTION (provided by applicant): The most important medical challenges include cardiovascular diseases, stroke, degenerative neurological diseases, diabetes, arthritis, osteoporosis, kidney and liver failure, spinal cord injury, burns, battlefield trauma, and other devastating conditions. Organ transplantation addresses some of these needs, but the scarcity of donors and the risk of immune suppression pose major limitations on transplantation. Regenerative medicine seeks to devise new ways to repair or replace damaged tissues and organs for millions of patients who cannot receive transplants. A core technology is the bioengineering of a functional tissue or organ by seeding living cells onto a biodegradable scaffold and then surgically implanting the construct into a patient. Tissue engineering involves extensive remodeling of cells and scaffolds. A major barrier to progress has been the inability to monitor this dynamic complex biological process in real-time, which makes control and optimization extremely difficult. On the other hand, as defined in the NIH roadmap molecular imaging plays an increasingly important role in the advancement of medicine. The optical molecular imaging tools has now allowed much better understanding of biological interactions at molecular and cellular levels in mouse models of almost all human diseases, and found several major clinical applications. Therefore, we are motivated to integrate these two forefront technologies in biomedical research - tissue engineering and optical molecular imaging - in a single unified framework, and drive a paradigm shift from static assays of cellular function in biopsied tissue or 2D culture models towards systematic analysis of 3D systems. The overall goal of this project is to develop a first-of-its-kind multi-probe multi-modal optical molecular tomography system for regenerative medicine and to demonstrate its utility in assessing the bioengineered blood vessels at the pre- and post-implantation stages. Fluorescent probes will be used to label the tubular scaffold and the two main cell types of blood vessels (endothelial cells lining the lumen, and smooth muscle cells in the wall). Optical fibers embedded within the scaffold will deliver laser light for optical coherence tomography and to excite the fluorescent probes. Innovative algorithms will be developed to reconstruct 3D distributions of multiple fluorescent probes. The proposed imaging system will first be used to track the development of bioengineered vessels in 100¿m resolution in a bioreactor mimicking blood flow conditions. Additional fluorescent probes will be used to monitor cell-specific gene expression and verify physiological responses of cells within the engineered vessel. The vessels will then be implanted as interposition grafts in the carotid arteries of living sheep, and will be imaged in 500¿m resolution to follow the tissue regeneration and function. Successful completion of the project will create new optical molecular imaging tools with a demonstrated application in vessel engineering, and have major and lasting impacts on many other areas in regenerative medicine. PUBLIC HEALTH RELEVANCE: Regenerative medicine creates an organ or tissue by seeding one's own cells onto a biodegradable scaffold and surgically implants it into him/her. Using bioengineered blood vessels as the first example, this project will develop a sophisticated optical imaging system to observe, analyze and optimize the complex processes of tissue regeneration in the laboratory and in live animals. The results will potentially benefit tens of millions of patients suffering from severely damaged vascular or nervous systems, heart, kidneys, liver, skeleton, bladder, or other organs.