Biodegradable stents: truly biodegradable with good tissue harmony
28 May 2013 (online)
A 48-year-old man presented to our hospital with corrosive (sulfuric acid)-induced esophageal and pyloric strictures and a barium study showing narrowing of a long segment in the distal esophagus ([Fig. 1 a]), reduced capacity of stomach, and antropyloric narrowing ([Fig. 1 b]). Balloon dilation (Boston Scientiﬁc, Natick, Massachusetts, USA) of esophageal and pyloric strictures was done over a period of 6 months. The pyloric stricture opened up, however, the esophageal stricture was refractory and the patient continued to have dysphagia. Therefore, an 80 mm × 23 mm SX-ELLA esophageal biodegradable stent (ELLA-CS, Hradec Králové, Czech Republic) was placed across the narrowed segment of the esophagus. Endoscopy revealed complete degradation at 12 weeks, and after 4 months the patient had symptomatic recurrence requiring dilation ([Fig. 2]). After 6 months of the placement of the biodegradable stent he underwent transhiatal esophagectomy with colonic transposition. The patient remained asymptomatic at follow-up after 6 months.
Macro/microscopic examinations revealed no evidence of stent material. The resected esophagus had a thickened wall with ulcerated mucosa and narrowed lumen ([Fig. 3]). On histological examination, the esophageal mucosa showed diffuse and deep ulcerations with marked submucosal fibrosis extending up to the muscularis propria ([Fig. 4 a]). The gastric mucosal lining (seen at the distal end in the figure) had deep ulcerations and many foreign body granulomas in the submucosa ([Fig. 4 b ,c]).
The biodegradation and tissue compatibility of biodegradable stents has been evaluated in animal studies only. Bergsma et al.  implanted poly-L-lactic acid (PLLA) particles subcutaneously in rats, and found a foreign body reaction at 3 weeks, followed by resolution at 16 weeks. Gogolewski et al.  and Schakenraad et al.  studied degradation of subcutaneously implanted PLLA copolymers in mice and observed that the macrophage and giant-cell infiltration decreased by 12 – 24 weeks along with polymer degradation. There is no literature on the biocompatibility of biodegradable stents in humans and no reports of histological changes in the esophagus even in animal studies. Our report is the first in a human case showing histological evidence of complete degradation of a biodegradable stent with good biocompatibility and minimal tissue reaction in the resected specimen.
- 1 Bergsma JE, Rozema FR, Bos RRM et al. In vivo degradation and biocompatibility study of in vitro pre-degraded as-polymerized polylactide particles. Biomaterials 1995; 16: 267-274
- 2 Gogolewski S, Jovanovic M, Perren SM et al. Tissue response and in vivo degradation of selected polyhydroxyacids: Polylactides (PLA), poly (3-hydroxybutyrate) (PHB), and poly (3-hydroxybutyrate-co-3-hydroxyvalerate) (PHB/VA). J Biomed Mater Res 1993; 27: 1135-1148
- 3 Schakenraad JM, Nieuwenhuis P, Molenaar I. In vivo and in vitro degradation of glycine/DL-lactic acid copolymers. J Biomed Mater Res 1989; 23: 1271-1288