TISSUE ENGINEERING FOR DIAPHRAGMATIC RECONSTRUCTION

先天性腹股沟疝（CDH）是困扰新生儿的最具破坏性的异常之一。先天性心脏病合并内脏疝导致胎儿肺发育不全，常与生命不相容。尽管CDH婴儿的预后以前很差，但新技术，如膜外膜氧合，高频喷射通气和一氧化氮延长了围产期后的生存期。胎儿气管阻塞提供了一种新的方法，以促进肺的生长和潜在的逆转肺发育不良。然而，CDH病理生理学的实际脑组织缺陷的确切修复仍然没有得到解决。虽然少数血管缺损可以初步闭合，但聚四氟乙烯（PTFE）补片闭合仍然是标准治疗。尽管其足以闭合缺损，但异物感染、复发性疝和粘连等长期问题仍然是PTFE的问题。本研究的目的是利用组织工程的原理，以开发一种新的膈肌，以修复先天性膈疝。用于制造新膈肌的组织将来自同一只动物的早期发育，避免了移植排斥的问题。首先，收获新生大鼠成肌细胞和成纤维细胞并在组织培养中建立。接下来，将用扩增的成肌细胞和成纤维细胞接种可生物降解的聚乙醇酸基质。最后，将在大鼠中产生骨缺损，并立即用可生物降解的结构修复。我们假设，随着聚乙醇酸基质的降解和分解，附着在基质上的成肌细胞和成纤维细胞将组织成重现原始隔膜的肌筋膜片。类似的方法已经在临床实践中用于替换新生儿的膀胱和皮肤缺陷。我们希望最终将这些方法应用于人类临床试验中的血管修复。

Congenital diaphragmatic hernia (CDH) is one of the most devastating anomalies afflicting the neonate. Visceral herniation associated with CDH results in fetal pulmonary hypoplasia often incompatible with life. Despite the previously dismal prognosis of babies with CDH, new technologies such as extracorporial membrane oxygenation, high frequency jet ventilation, and nitric oxide have extended survival past the peri-natal period. Fetal tracheal occlusion has provided a novel method to promote lung growth and potentially reverse pulmonary hypoplasia. Conclusive repair of the actual diaphragmatic defect responsible for the pathophysiology of CDH, however, still remains unsolved. Although a minority of diaphragmatic defects can be closed primarily, patch closure with polytetrafluoroethylene (PTFE) remains the standard of care. Despite its adequacy for closing the defect, long-term problems such as foreign body infection, recurrent herniation, and adhesions remain a problem with PTFE. The objective of this study is to utilize the principles of tissue engineering in order to develop a neodiaphragm for repair of congenital diaphragmatic hernia. Tissue harvested for the creation of the neodiaphragm will come from the same animal at an earlier point in its development, avoiding the problem of graft rejection. First, neonatal rat myoblasts and fibroblasts will be harvested and established in tissue culture. Next, a biodegradable polyglycolic acid matrix will be seeded with the expanded myoblasts and fibroblasts. Finally, a diaphragmatic defect will be created in a rat and immediately repaired with the biodegradable construct. We hypothesize that with the degradation and breakdown of the polyglycolic acid matrix the myoblasts and fibroblasts attached to the matrix will organize into a myofascial sheet recapitulating the original diaphragm. Similar methods have already been used in clinical practice to replace bladder and skin defects in the neonate. We hope to ultimately apply these methods toward diaphragmatic repair in human clinical trials.