Biocompatibility of a new device of self-expandable covered and non-covered tracheal stent: comparative study in rats

Abstract

PURPOSE:To investigate the compatibility of a new model of self-expandable tracheal stent in rats. METHODS:A new device of polyurethane covered and non -covered stent was placed in the trachea of Wistar rats. Animals were distributed in two groups: the polyurethane covered and non-covered group. Macroscopic parameters included position within the tracheal lumen, adherence to the mucosa, degree of dilatation, permeability and internal diameter. Microscopic findings evaluated were: incorporation, inflammatory activity, granulation tissue and epithelial revetment injuries. The observation follow-up was six weeks.All parameters were quantified based on determined score values. Incorporation of the stents was evaluated based on the observation if the stent was fixed into the trachea or if it could be removed. Degree of dilatation was performed by external diameter measurements. Granulation tissue was evaluated by measurements of height of the tissue growing into the tracheal lumen.RESULTS: 100% of non-covered stents had total attachment to mucosa and 100% of polyurethane covered type had adherence only.Regarding dilatation, granulation tissue, inflammatory activity and internal diameter measurements, there were no significant differences between the groups. Pathological tracheal wall injuries were present in both groups. Biocompatibility of a new device of self-expandable covered and non-covered tracheal stent. CONCLUSION:

State of the Science in Tracheal Stents: A Scoping Review

“…Hybrid stents are often referred to as a “covered” or “coated” stents. In our review, 19 studies employed hybrid stents as outlined in Tables I–III 4,20,27,36–51 . This diverse group of stents utilized a stainless steel or nitinol framework coated with polyurethane (n = 7), 20,27,40–42,44,48 silicone (n = 3), 39,49,50 expanded polytetrafluoroethylene (n = 1), 49 polyester (n = 1), 49 polypropylene (n = 1), 49 unspecified material (n = 4), 4,38,43,45 and drug‐eluting polymers (n = 3) 46,47,51 .…”

“…Twenty-eight studies employed bare metallic stents, grouped into four distinct types: steel, [10][11][12][13][14][15][16][17][18][19] nitinol (Ni-Ti alloy), 4,12,13,[19][20][21][22][23][24][25][26][27][28][29] magnesium alloys, [30][31][32][33] and elgiloy (Co-Cr-Ni alloy) 23,34 as outlined in portions of Tables I-III. Only two studies failed to identify the metal used in the employed tracheal stent.…”

“…In our review, 19 studies employed hybrid stents as outlined in Tables I-III. 4,20,27,[36][37][38][39][40][41][42][43][44][45][46][47][48][49][50][51] This diverse group of stents utilized a stainless steel or nitinol framework coated with polyurethane (n = 7), 20,27,[40][41][42]44,48 silicone (n = 3), 39,49,50 expanded polytetrafluoroethylene (n = 1), 49 polyester (n = 1), 49 polypropylene (n = 1), 49 unspecified material (n = 4), 4,38,43,45 and drug-eluting polymers (n = 3). 46,47,51 Ten of the 20 studies cited here employed a nitinol backbone, 3 studies specified stainless steel, and 5 did not specify the exact material of the metallic backbone of the stent.…”

Comparison of three kinds of self-expandable metallic stents induced granulation tissue hyperplasia in the rabbit trachea

“…Stent placements in a healthy luminal organ to explore stent-induced tissue hyperplasia have been successfully performed in trachea 13 , 14 , oesophagus 15 and urethra 16 , 17 . The candidate animal models include rabbit, pig, canine and rat.…”

Management of tracheobronchial obstruction in infants using metallic stents: long-term outcome

“…In the recent series by Siegel et al, [24] Recently, new stents that are more biocompatible were being investigated. [25,26] Biodegradable materials had been used experimentally for stenting of tracheobronchial stenosis since 1998. Polydioxanone is a biodegradable polymer that exhibits some shape memory and dissolves by 15 weeks.…”