Cardiac Regeneration through Growth Factor Eluting Microrod Scaffolds

描述（由申请人提供）： 在美国，500万心力衰竭患者由于收缩性肌细胞的不可逆损伤而具有不良的心脏泵送。因此，通过细胞和组织工程来恢复心脏功能是非常期望的。本申请中提出的新方法结合了生物工程和基于细胞生物学的技术，以直接靶向心肌再生，这是当前疗法未很好解决的重要临床问题。我们已经系统地递送了机械生长因子（MGF）的人工稳定形式（24个氨基酸，来自激素原的E-结构域肽），其是胰岛素样生长因子（IGF）家族的成员，并且显示出在衰竭小鼠心脏中的功能恢复，沿着驻留祖细胞的动员。我们通过提供微棒支架（MRS）来利用心脏的天然修复能力，不仅递送天然的、可快速降解的MGF，而且还提供适当的细胞连接和分化所必需的局部机械和地形线索。我们的总体假设是，由MRS局部递送的MGF和IGF-1的定时释放再生并加强受损的心肌而没有有害的副作用。这在培养物和动物模型中的祖细胞/干细胞和心肌细胞上进行测试。 具体目标1确定刚度变化对在3D微棒支架中生长的细胞的影响。我们优化了MRS特征，用于调节干细胞和心肌细胞的细胞增殖、谱系定型、分化、收缩成熟和连接。 特定目标2确定生长因子（GF）加载的MRS在模拟正常和缺血心脏的环境条件下的作用。我们表征包封效率，GF的生物稳定性，和脱细胞释放动力学的洗脱MRS在体外。我们确定从MRS中释放的GF对祖细胞/干细胞和新生大鼠心室肌细胞增殖和迁移的影响，以建立在模拟正常和缺血心脏的培养条件下基因表达和细胞存活的变化。 特定目标3确定在MRS将GF递送至梗死边缘区后，在心肌梗死后的不同阶段发生的细胞、分子和功能增益。我们研究了GF释放如何影响体内心脏祖细胞的迁移和分化。我们研究了局部MGF肽递送对心脏功能、预防心肌细胞凋亡、预防不良心脏重塑和减少瘢痕形成的有益作用。 我们的长期目标是开发微棒MGF疗法，支持心肌再生，以恢复衰竭的人类心脏的心脏功能。 公共卫生相关性声明（由申请人提供）：心力衰竭是一种常见疾病，具有很高的残疾和死亡率。目前的估计是，心力衰竭在美国每年约占100万住院治疗和100亿美元的医疗保健费用。心力衰竭的主要潜在原因是缺血性心脏病、高血压和特发性扩张型心肌病，其共同的病理生理特征是功能性心肌细胞质量不足。该提案开发并测试了一种新型治疗性3D洗脱微棒支架（MRS）系统，以提供天然心脏生长因子，用于帮助培养和动物模型中受损心肌的再生和恢复。

DESCRIPTION (provided by applicant): Five million heart failure patients in the US have poor cardiac pumping due to irreversible damage of the contractile myocytes. Thus, recovery of cardiac function by cell and tissue engineering is highly desirable. The novel approach proposed in this application combines bioengineering and cell biology-based techniques to directly target the regeneration of heart muscle, which is an important clinical problem not well addressed by current therapies. We have systemically delivered an artificial stabilized form of the mechano-growth factor (MGF), (24 amino acid, E-domain peptide from the prohormone) that is a member of the insulin-like growth factor (IGF) family and shown recovery of function in failing mouse hearts along with the mobilization of resident progenitor cells. We take advantage of the natural repair capacity of the heart by providing a microrod scaffold (MRS) to not only deliver the native, rapidly degradable MGF, but also provide local mechanical and topographic cues necessary for proper cellular connectivity and differentiation. Our overall hypothesis is that timed release of MGF and IGF-1 delivered locally by the MRS regenerates and strengthens the damaged myocardium without harmful side effects. This is tested on progenitor/stem cells and cardiac myocytes in culture and in animal models. Specific Aim 1 determines the effect of stiffness variation on cells grown in 3D microrod scaffolds. We optimize MRS characteristics for regulation of cell proliferation, lineage commitment, differentiation, contractile maturity and connectivity of stem cells and cardiac myocytes. Specific Aim 2 determines the effect of growth factor (GF)-loaded MRS in environmental conditions that mimic the normal and ischemic heart. We characterize encapsulation efficiency, GF biostability, and acellular release kinetics of the eluting MRS in vitro. We determine effects of GF release from MRS on proliferation and migration of progenitor/ stem and neonatal rat ventricular myocytes to establish changes in gene expression and cell survival under culture conditions that mimic the normal and ischemic heart. Specific Aim 3 determines the cellular, molecular and functional gains that occur at different stages following myocardial infarction after MRS delivery of GFs to the border zone of an infarct. We examine how GF release affects the migration and differentiation of cardiac progenitor cells in vivo. We examine the beneficial effects of localized MGF peptide delivery on cardiac function, prevention of cardiac myocyte apoptosis, prevention of adverse cardiac remodeling, and reduced scar formation. Our long-term goal is to develop microrod MGF therapy that supports the regeneration of cardiac muscle to regain cardiac function in the failing human heart. Public Health Relevance Statement (provided by applicant): Heart failure is a common condition carrying a high burden of disability and mortality. Current estimates are that heart failure accounts for approximately one million hospitalizations and $10 billion in health care costs in the United States per year. The main underlying causes of heart failure are ischemic heart disease, hypertension and idiopathic dilated cardiomyopathy, whose common pathophysiologic characteristic is an inadequate mass of functional myocytes. This proposal develops and tests a novel therapeutic 3D eluting microrod scaffold (MRS) system to deliver a natural cardiac growth factor for aiding in the regeneration and recovery of damaged cardiac muscle in culture and animal models.