TISSUE ENGINEERING FOR DIAPHRAGMATIC RECONSTRUCTION

先天性膈疝（CDH）是困扰新生儿的最具破坏性的异常之一。与CDH相关的内脏疝导致胎儿肺发育不全，通常与生活不相容。尽管先前CDH患儿预后不佳，但体外膜氧合、高频喷射通气和一氧化氮等新技术延长了围产儿的生存期。胎儿气管闭塞提供了一种促进肺生长和可能逆转肺发育不全的新方法。然而，导致CDH病理生理的膈肌缺损的结论性修复仍未得到解决。虽然少数膈肌缺损可以主要封闭，但聚四氟乙烯（PTFE）补片封闭仍然是标准的护理方法。尽管它足以关闭缺陷，但长期的问题，如异物感染，复发性疝和粘连仍然是PTFE的问题。本研究的目的是利用组织工程的原理来开发用于修复先天性膈疝的新隔膜。为制造新横膈膜而采集的组织将来自同一只动物在其发育的早期阶段，避免了移植排斥的问题。首先，收集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，一个可生物降解的聚乙醇酸基质将与扩增的成肌细胞和成纤维细胞一起播种。最后，在大鼠身上制造膈肌缺损，并立即用可生物降解的构造物修复。我们推测，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一个肌筋膜片，再现原来的隔膜。类似的方法已经在临床实践中用于替换新生儿膀胱和皮肤缺陷。我们希望最终将这些方法应用于膈肌修复的人体临床试验。

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.