Dharmadhikari Sayali, Best Cameron A, King Nakesha, Henderson Michaela, Johnson Jed, Breuer Christopher K, Chiang Tendy
1 Center for Regenerative Medicine, Research Institute at Nationwide Children's Hospital, Columbus, Ohio, USA.
2 Department of Otolaryngology, Nationwide Children's Hospital, Columbus, Ohio, USA.
Ann Otol Rhinol Laryngol. 2019 May;128(5):391-400. doi: 10.1177/0003489419826134. Epub 2019 Jan 30.
The clinical experience with tissue-engineered tracheal grafts (TETGs) has been fraught with graft stenosis and delayed epithelialization. A mouse model of orthotopic replacement that recapitulates the clinical findings would facilitate the study of the cellular and molecular mechanisms underlying graft stenosis.
Electrospun nanofiber tracheal scaffolds were created using nonresorbable (polyethylene terephthalate + polyurethane) and co-electrospun resorbable (polylactide-co-caprolactone/polyglycolic acid) polymers (n = 10/group). Biomechanical testing was performed to compare load displacement of nanofiber scaffolds to native mouse tracheas. Mice underwent orthotopic tracheal replacement with syngeneic grafts (n = 5) and nonresorbable (n = 10) and resorbable (n = 10) scaffolds. Tissue at the anastomosis was evaluated using hematoxylin and eosin (H&E), K5+ basal cells were evaluated with the help of immunofluorescence testing, and cellular infiltration of the scaffold was quantified. Micro computed tomography was performed to assess graft patency and correlate radiographic and histologic findings with respiratory symptoms.
Synthetic scaffolds were supraphysiologic in compression tests compared to native mouse trachea ( P < .0001). Nonresorbable scaffolds were stiffer than resorbable scaffolds ( P = .0004). Eighty percent of syngeneic recipients survived to the study endpoint of 60 days postoperatively. Mean survival with nonresorbable scaffolds was 11.40 ± 7.31 days and 6.70 ± 3.95 days with resorbable scaffolds ( P = .095). Stenosis manifested with tissue overgrowth in nonresorbable scaffolds and malacia in resorbable scaffolds. Quantification of scaffold cellular infiltration correlated with length of survival in resorbable scaffolds (R = 0.95, P = .0051). Micro computed tomography demonstrated the development of graft stenosis at the distal anastomosis on day 5 and progressed until euthanasia was performed on day 11.
Graft stenosis seen in orthotopic tracheal replacement with synthetic tracheal scaffolds can be modeled in mice. The wide array of lineage tracing and transgenic mouse models available will permit future investigation of the cellular and molecular mechanisms underlying TETG stenosis.
组织工程气管移植物（TETG）的临床应用一直饱受移植物狭窄和上皮化延迟之苦。一种能重现临床发现的原位置换小鼠模型将有助于研究移植物狭窄背后的细胞和分子机制。
使用不可吸收（聚对苯二甲酸乙二酯+聚氨酯）和共电纺可吸收（聚丙交酯-共-己内酯/聚乙醇酸）聚合物制作电纺纳米纤维气管支架（每组n = 10）。进行生物力学测试以比较纳米纤维支架与天然小鼠气管的载荷位移。小鼠接受同基因移植物（n = 5）以及不可吸收（n = 10）和可吸收（n = 10）支架的原位气管置换。使用苏木精和伊红（H&E）对吻合处组织进行评估，借助免疫荧光测试评估K5 + 基底细胞，并对支架的细胞浸润进行定量分析。进行微型计算机断层扫描以评估移植物通畅情况，并将影像学和组织学结果与呼吸症状相关联。
与天然小鼠气管相比，合成支架在压缩测试中表现出超生理状态（P <.0001）。不可吸收支架比可吸收支架更硬（P =.0004）。80%的同基因受体存活至术后60天的研究终点。不可吸收支架的平均存活时间为11.40±7.31天，可吸收支架为6.70±3.95天（P =.095）。狭窄表现为不可吸收支架中的组织过度生长和可吸收支架中的软化。支架细胞浸润的定量分析与可吸收支架中的存活时间相关（R = 0.95，P =.0051）。微型计算机断层扫描显示在第5天远端吻合处出现移植物狭窄，并持续发展直至在第11天实施安乐死。
在小鼠中可以模拟用合成气管支架进行原位气管置换时出现的移植物狭窄。现有的大量谱系追踪和转基因小鼠模型将有助于未来对TETG狭窄背后的细胞和分子机制进行研究。
