Abstract：
OBJECTIVE: Utilizing a novel histopathological scoring system and subglottic stenosis (SGS) rabbit model, we aimed to compare degrees of inflammation and severity of narrowing in the subglottis between two minimally invasive therapeutic modalities: endoscopic balloon dilation (EBD) alone versus EBD with placement of a bioabsorbable ultra-high ductility magnesium (UHD-Mg) alloy stent.
METHODS: SGS was induced endoscopically via microsuspension laryngoscopy in 23 New Zealand white rabbits. The control group (n = 11) underwent EBD alone, the study arm (n = 12) underwent EBD with implantation of bioabsorbable UHD-Mg alloy stents. Rabbits were euthanized at 2-, 3-, and 6-weeks after SGS induction, coinciding with wound healing stages. Using Optical Coherence Tomography (OCT), cross-sectional areas of airways were compared to calculate the mean percentage of intraluminal area at sequential time points. A novel histopathological scoring system was used to analyze frozen sections of laryngotracheal complexes. The degree of inflammation was quantified by scoring changes in inflammatory cell infiltration, epithelial ulceration/metaplasia, subepithelial edema/fibrosis, and capillary number/dilation. Univariate analysis was utilized to analyze these markers.
RESULTS: We found rabbits implanted with the bioabsorbable UHD-Mg alloy stent had statistically significantly higher scores in categories of hyperplastic change (stents vs controls: 1.48 vs 0.46 p < 0.001), squamous metaplasia (22 vs 5 p < 0.001), and neutrophils/fibrin in lumen (31 vs 8, p < 0.001). Rabbits who received EBD alone had higher scores of subepithelial edema and fibrosis (2.70 vs 3.49, p < 0.0256). The stented rabbits demonstrated significantly increased mean percent stenosis by intraluminal mean area compared to controls at 2 weeks (88.56 vs 58.98, p = 0.032), however at all other time points there was no significant difference between intraluminal subglottic stenosis by mean percent stenosis area.
CONCLUSIONS: Rabbits with SGS treated with UHD-Mg alloy stents demonstrated histopathologic findings suggestive of lower levels of tracheal fibrosis. This could indicate a reduced tendency towards the development of stenosis when compared to EBD alone. There was not a difference in luminal size between stent and non-stented rabbits at the six-week end point. Histologically, however, overall the use of bioabsorbable UHD-Mg alloy stenting elicited a greater tissue response at the level of the superficial mucosa rather than fibrosis of the lamina propria seen in the stented rabbits. This suggests more favorable healing and less of a tendency towards fibrosis and stenosis even though there may not be a benefit from a luminal size standpoint during this early healing period. Compared to known complications of currently available non-bioabsorbable metal or silicone-based stents, this proof-of-concept investigation highlights the potential use of a novel biodegradable UHD-Mg stent as a therapeutic modality for pediatric SGS.
METHODS: SGS was induced endoscopically via microsuspension laryngoscopy in 23 New Zealand white rabbits. The control group (n = 11) underwent EBD alone, the study arm (n = 12) underwent EBD with implantation of bioabsorbable UHD-Mg alloy stents. Rabbits were euthanized at 2-, 3-, and 6-weeks after SGS induction, coinciding with wound healing stages. Using Optical Coherence Tomography (OCT), cross-sectional areas of airways were compared to calculate the mean percentage of intraluminal area at sequential time points. A novel histopathological scoring system was used to analyze frozen sections of laryngotracheal complexes. The degree of inflammation was quantified by scoring changes in inflammatory cell infiltration, epithelial ulceration/metaplasia, subepithelial edema/fibrosis, and capillary number/dilation. Univariate analysis was utilized to analyze these markers.
RESULTS: We found rabbits implanted with the bioabsorbable UHD-Mg alloy stent had statistically significantly higher scores in categories of hyperplastic change (stents vs controls: 1.48 vs 0.46 p < 0.001), squamous metaplasia (22 vs 5 p < 0.001), and neutrophils/fibrin in lumen (31 vs 8, p < 0.001). Rabbits who received EBD alone had higher scores of subepithelial edema and fibrosis (2.70 vs 3.49, p < 0.0256). The stented rabbits demonstrated significantly increased mean percent stenosis by intraluminal mean area compared to controls at 2 weeks (88.56 vs 58.98, p = 0.032), however at all other time points there was no significant difference between intraluminal subglottic stenosis by mean percent stenosis area.
CONCLUSIONS: Rabbits with SGS treated with UHD-Mg alloy stents demonstrated histopathologic findings suggestive of lower levels of tracheal fibrosis. This could indicate a reduced tendency towards the development of stenosis when compared to EBD alone. There was not a difference in luminal size between stent and non-stented rabbits at the six-week end point. Histologically, however, overall the use of bioabsorbable UHD-Mg alloy stenting elicited a greater tissue response at the level of the superficial mucosa rather than fibrosis of the lamina propria seen in the stented rabbits. This suggests more favorable healing and less of a tendency towards fibrosis and stenosis even though there may not be a benefit from a luminal size standpoint during this early healing period. Compared to known complications of currently available non-bioabsorbable metal or silicone-based stents, this proof-of-concept investigation highlights the potential use of a novel biodegradable UHD-Mg stent as a therapeutic modality for pediatric SGS.
摘要：
目的：利用新型组织病理学评分系统和声门下狭窄（SGS）兔模型，我们的目的是比较两种微创治疗方式之间的声门下炎症程度和狭窄的严重程度:内镜下球囊扩张术(EBD)和EBD单独放置生物可吸收超高延展性镁(UHD-Mg)合金支架.
方法：通过微悬浮喉镜对23只新西兰大白兔进行内窥镜诱导SGS。对照组（n=11）仅接受EBD，研究组（n=12）接受了EBD，并植入了生物可吸收的UHD-Mg合金支架。兔子在2-，3-,SGS诱导后6周，与伤口愈合阶段相吻合。使用光学相干断层扫描（OCT），比较气道横截面积以计算连续时间点的管腔内面积的平均百分比.一种新颖的组织病理学评分系统用于分析喉气管复合体的冷冻切片。炎症程度通过炎症细胞浸润的评分变化来量化，上皮性溃疡/上皮化生，上皮下水肿/纤维化，和毛细管数/扩张。利用单变量分析来分析这些标志物。
结果：我们发现植入生物可吸收UHD-Mg合金支架的兔子在增生性变化类别中具有统计学上显着的更高得分（支架与对照：1.48vs0.46p<0.001），鳞状上皮化生（22vs5p<0.001），和腔内的中性粒细胞/纤维蛋白（31vs8，p<0.001）。单独接受EBD的兔上皮下水肿和纤维化评分更高(2.70vs3.49,p<0.0256)。与2周时的对照组相比，支架兔显示出管腔内平均面积的平均狭窄百分比显着增加（88.56vs58.98，p=0.032），然而，在所有其他时间点，腔内声门下狭窄的平均狭窄面积百分比没有显着差异。
结论：用UHD-Mg合金支架治疗的SGS兔表现出组织病理学结果提示气管纤维化水平较低。与单独的EBD相比，这可能表明狭窄发展的趋势降低。在六周结束时，支架和非支架兔之间的管腔大小没有差异。组织学上,然而,总体而言，使用可生物吸收的UHD-Mg合金支架在表面粘膜水平引起更大的组织反应，而不是在支架兔中看到的固有层纤维化。这表明更有利的愈合和更少的纤维化和狭窄的倾向,即使在该早期愈合期间从管腔尺寸的观点来看可能没有益处。与目前可用的非生物可吸收金属或硅酮基支架的已知并发症相比，这项概念验证研究强调了新型可生物降解UHD-Mg支架作为儿科SGS治疗方式的潜在用途.
方法：通过微悬浮喉镜对23只新西兰大白兔进行内窥镜诱导SGS。对照组（n=11）仅接受EBD，研究组（n=12）接受了EBD，并植入了生物可吸收的UHD-Mg合金支架。兔子在2-，3-,SGS诱导后6周，与伤口愈合阶段相吻合。使用光学相干断层扫描（OCT），比较气道横截面积以计算连续时间点的管腔内面积的平均百分比.一种新颖的组织病理学评分系统用于分析喉气管复合体的冷冻切片。炎症程度通过炎症细胞浸润的评分变化来量化，上皮性溃疡/上皮化生，上皮下水肿/纤维化，和毛细管数/扩张。利用单变量分析来分析这些标志物。
结果：我们发现植入生物可吸收UHD-Mg合金支架的兔子在增生性变化类别中具有统计学上显着的更高得分（支架与对照：1.48vs0.46p<0.001），鳞状上皮化生（22vs5p<0.001），和腔内的中性粒细胞/纤维蛋白（31vs8，p<0.001）。单独接受EBD的兔上皮下水肿和纤维化评分更高(2.70vs3.49,p<0.0256)。与2周时的对照组相比，支架兔显示出管腔内平均面积的平均狭窄百分比显着增加（88.56vs58.98，p=0.032），然而，在所有其他时间点，腔内声门下狭窄的平均狭窄面积百分比没有显着差异。
结论：用UHD-Mg合金支架治疗的SGS兔表现出组织病理学结果提示气管纤维化水平较低。与单独的EBD相比，这可能表明狭窄发展的趋势降低。在六周结束时，支架和非支架兔之间的管腔大小没有差异。组织学上,然而,总体而言，使用可生物吸收的UHD-Mg合金支架在表面粘膜水平引起更大的组织反应，而不是在支架兔中看到的固有层纤维化。这表明更有利的愈合和更少的纤维化和狭窄的倾向,即使在该早期愈合期间从管腔尺寸的观点来看可能没有益处。与目前可用的非生物可吸收金属或硅酮基支架的已知并发症相比，这项概念验证研究强调了新型可生物降解UHD-Mg支架作为儿科SGS治疗方式的潜在用途.
