Tissue Engineered Aortic Heart Valves: Scaffolds and Stem Cells

组织工程主动脉心脏瓣膜：支架和干细胞

• 批准号: 8215809
• 负责人: Dan TEODOR Simionescu
• 金额: $ 35.64万
• 依托单位: CLEMSON UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-03-01 至 2014-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8215809
• 关键词: 3-Dimensional; Adult; Allografting; Architecture; Arteries; Autologous; Behavior; Binding; Biochemical; Biodegradation; Biological; Bioreactors; Blood; Cardiac; Cardiovascular Diseases; Cell Differentiation process; Cell Shape; Cells; Child; Coagulation Process; Collagen; Cues; Data; Devices; Elastases; Elements; Endocarditis; Engineering; Environment; Extracellular Matrix; Failure; Family suidae; Gel; Glucose; Glycosaminoglycans; Goals; Growth Factor; Heart; Heart Valve Diseases; Heart Valves; Histologic; Homeostasis; Human; In Vitro; Infiltration; Life; Literature; Mechanics; Mesenchymal Stem Cells; Molds; Natural regeneration; Operative Surgical Procedures; Patients; Pentas; Phenotype; Physiological; Plant Roots; Preparation; Procedures; Property; Public Health; Reporting; Risk; Science; Seeds; Shapes; Signal Transduction; Silicone Elastomers; Source; Stem cells; Structure; Surgeon; Surgical Flaps; System; Tannic Acid; Testing; Time; Tissue Engineering; Tissues; analog; aortic valve; biodegradable polymer; biomaterial compatibility; calcification; conditioning; crosslink; design; heart valve replacement; hemodynamics; implantation; improved; in vivo; innovation; interstitial cell; pericardial sac; pressure; public health relevance; reconstruction; response; scaffold; stem cell differentiation; tissue support frame

DESCRIPTION (provided by applicant): Worldwide, nearly 300,000 diseased heart valves are replaced annually, most of them with devices that include mechanical valves, devices made from non-living biological tissues or viable human allografts. Durability of heart valve replacements is limited to 15-20 years mostly due to coagulation risks, endocarditis, degeneration, calcification and failure to grow and remodel. This study is highly relevant to public health because heart valve disease is a very important chapter of cardiovascular diseases in adults and children. Our long-term objective is to develop living tissue-engineered valves that will last a life-time, will not be prone to complications, will have the ability to grow and remodel and thus ultimately impacting thousands of patients. Our innovative proposal acknowledges the vital importance of four issues that are unique to our approach: i) Constructs made from partially stabilized collagenous scaffolds, ii) Anatomically analogous 3-D heart valve shapes made form tri-layered structures that mimic the native heart valve histo-architecture, iii) Autologous multipotent mesenchymal stem cells for repopulation and remodeling and iv) Mechanical and biochemical cues to induce stem cell differentiation into valvular cells capable of maintaining matrix homeostasis. To accomplish these goals, we propose to develop partially stabilized collagen scaffolds that structurally and functionally mimic the aortic valve fibrosa, ventricularis and spongiosa layers, to assemble them into tri-layered constructs shaped in the form of natural heart valves and populate them with human mesenchymal stem cells. Constructs will be mounted in a bioreactor to induce differentiation of stem cells into analogues of valvular interstitial cells and promote remodeling. In Specific Aim 1, collagen layers to be used as fibrosa and ventricularis layers will be prepared from decellularized pericardium and lightly cross-linked to allow for controlled biodegradation. For the spongiosa layer, highly porous collagen scaffolds will be prepared from decellularized, elastase- treated arteries and enriched with valve-specific glycosaminoglycans. Scaffolds will be then assembled into histologically analogous tri-layered structures (fibrosa / spongiosa / ventricularis) and shaped into constructs resembling native aortic roots by molding on silicone rubber casts. Engineered aortic roots will be characterized by advanced mechanical analysis and their function evaluated in a pulsatile valve duplicator. In Specific Aim 2, we will prepare human mesenchymal stem cells. Stem cells will be then seeded onto collagen gels and subjected to controlled load regimes in a FlexerCell system. We will evaluate phenotypic changes and ability of stimulated stem cells to differentiate into valvular interstitial cells. In Specific Aim 3, we will encase spongiosa layer within the tri-layered scaffold, seed the scaffolds with stem cells, and subject constructs to in vitro cycling within a bioreactor. We will evaluate cell differentiation and matrix remodeling at various time-points in dynamic conditions. PUBLIC HEALTH RELEVANCE: Heart valves are flap-like tissues inside the heart chambers that open and close every second of the cardiac cycle to allow blood to flow through the heart. Diseased heart valves are routinely replaced by surgery, but available artificial devices are less than optimal and fail within 15-20 years after implantation, mostly because they are made of non-living materials. New and improved devices are needed for more than 300,000 patients every year. We are developing living materials comprised of layers of tissue scaffolds to which we add the own patients' cells and shape the entire device in the form of a natural heart valve. This tissue engineered device has the potential to adapt and remodel with the patient, and thus will have a global impact by treating cardiovascular diseases in adults and children.

描述（由申请人提供）：全球，每年将近300,000个患病的心脏瓣膜更换，其中大多数带有包括机械阀，由非生存生物组织制成的设备或可行的人类同种异体移植物。心脏瓣膜更换的耐用性限制为15 - 20年，主要是由于凝血风险，心内膜炎，变性，钙化和未能生长和重塑。这项研究与公共卫生高度相关，因为心脏瓣膜疾病是成人和儿童心血管疾病的非常重要的一章。我们的长期目标是发展将持续一生的生存组织工程瓣膜，不容易发生并发症，将具有成长和改造的能力，从而最终影响数千名患者。我们的创新提议承认我们方法是四个问题的至关重要的：生化线索诱导干细胞分化成能够维持基质稳态的瓣膜细胞。为了实现这些目标，我们建议开发部分稳定的胶原蛋白支架，这些胶原蛋白支架在结构和功能上模仿了主动脉瓣纤维，心室和海绵层层，以将它们组装成三层构造中，以自然心脏瓣膜形式形成，并用人腔茎细胞填充它们。构建体将安装在生物反应器中，以诱导干细胞分化为瓣膜间质细胞的类似物并促进重塑。在特定的目标1中，将用胶原蛋白层用作纤维状和心室层，从脱毛的心包中制备并轻轻地交联以进行控制的生物降解。对于海绵层，将通过脱细胞化的，弹性酶处理的动脉制备高度多孔的胶原蛋白支架，并富含瓣膜特异性糖胺聚糖。然后，脚手架将组装成组织学类似的三层结构（Fibrosa / Spongiosa / contricularis），并通过在硅橡胶铸件上成型，形成类似于天然主动脉根的构造。工程主动脉根的特征是高级机械分析及其在脉冲阀复制子中评估的功能。在特定的目标2中，我们将准备人类间充质干细胞。然后将干细胞接种到胶原蛋白凝胶上，并在弯曲系统中受到控制的负载状态。我们将评估表型变化和刺激干细胞分化为瓣膜间质细胞的能力。在特定的目标3中，我们将在三层支架内包含长海绵层，用干细胞播种脚手架，并在生物反应器中进行体外循环。我们将在动态条件下在各个时间点上评估细胞分化和基质重塑。 公共卫生相关性：心脏瓣膜是心脏室内的瓣状组织，它们打开和关闭心脏周期的每一秒，以使血液流过心脏。患病的心脏瓣膜通常被手术替换，但是可用的人造装置却不是最佳的，并且在植入后的15 - 20年内失败，主要是因为它们是由非生存材料制成的。每年有300,000多名患者需要新的和改进的设备。我们正在开发由组织支架层组成的生存材料，并以天然心脏瓣膜的形式添加自己的患者细胞并塑造整个设备。该组织工程装置有可能与患者进行适应和改造，因此通过治疗成人和儿童的心血管疾病会产生全球影响。