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）：全世界每年有近 300,000 个患病心脏瓣膜被更换，其中大多数使用的装置包括机械瓣膜、由无生命的生物组织或可行的人类同种异体移植物制成的装置。心脏瓣膜置换术的耐久性仅限于 15-20 年，主要是由于凝血风险、心内膜炎、变性、钙化以及生长和重塑失败。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中非常重要的一章。我们的长期目标是开发活体组织工程瓣膜，这种瓣膜可以终生使用，不易出现并发症，具有生长和重塑的能力，从而最终影响成千上万的患者。我们的创新提案承认我们方法所特有的四个问题的至关重要性：i) 由部分稳定的胶原支架制成的结构，ii) 解剖学上相似的 3D 心脏瓣膜形状形成三层结构，模仿天然心脏瓣膜组织-架构，iii) 用于再增殖和重塑的自体多能间充质干细胞，以及 iv) 诱导干细胞分化为能够维持基质的瓣膜细胞的机械和生化线索体内平衡。为了实现这些目标，我们建议开发部分稳定的胶原支架，在结构和功能上模仿主动脉瓣纤维层、心室层和海绵层，将它们组装成天然心脏瓣膜形状的三层结构，并用人类间充质细胞填充它们干细胞。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。在具体目标 1 中，用作纤维层和心室层的胶原层将从脱细胞心包中制备并轻微交联以允许受控生物降解。对于海绵层，将由脱细胞、弹性蛋白酶处理的动脉制备高度多孔的胶原支架，并富含瓣膜特异性糖胺聚糖。然后支架将被组装成组织学上类似的三层结构（纤维/海绵体/心室），并通过在硅橡胶铸件上成型而形成类似于天然主动脉根部的结构。工程化主动脉根部将通过先进的机械分析进行表征，并在脉动瓣膜复制器中评估其功能。在具体目标2中，我们将制备人间充质干细胞。然后，干细胞将被接种到胶原蛋白凝胶上，并在 FlexerCell 系统中接受受控的负载方案。我们将评估受刺激的干细胞的表型变化和分化为瓣膜间质细胞的能力。在具体目标 3 中，我们将把海绵层包裹在三层支架内，在支架上接种干细胞，并使构建体在生物反应器内进行体外循环。我们将评估动态条件下不同时间点的细胞分化和基质重塑。 公众健康相关性：心脏瓣膜是心腔内的瓣状组织，在心动周期的每一秒打开和关闭，以允许血液流经心脏。患病的心脏瓣膜通常通过手术进行替换，但现有的人工装置并不理想，并且会在植入后 15-20 年内失效，主要是因为它们是由非生命材料制成的。每年有超过 300,000 名患者需要新的和改进的设备。我们正在开发由多层组织支架组成的活体材料，我们将患者自己的细胞添加到其中，并将整个装置塑造成天然心脏瓣膜的形式。这种组织工程设备具有适应患者并进行改造的潜力，因此将通过治疗成人和儿童的心血管疾病产生全球影响。