A drug-carrying, multiscene, absorbable biological suture from fish swim bladder.

BACKGROUND

Traditional sutures often fail to meet the complex demands of wound closure across diverse anatomical environments. This study introduces a novel drug-eluting, multiscene absorbable biological suture derived from decellularized fish swim bladder, designed to address limitations in mechanical performance, pH resistance, and foreign body reactions.

METHODS

Swim bladders were decellularized, microdissected into 0.3-mm strips, and functionalized with rapamycin (RAPA) or necrostatin-1 (NEC-1) via hyaluronic acid/polyvinyl alcohol coatings. Sutures were evaluated for cytotoxicity [human umbilical vein endothelial cell (HUVEC) assays], mechanical properties (tensile/acid/alkali resistance), and efficacy in rat models of venous/arterial, intestinal, gastric, and abdominal wall closures ( n = 3/group). Histological (hematoxylin and eosin, immunofluorescence) and scanning electron microscopy analyses were performed.

RESULTS

The NEC-1 sutures demonstrated superior tensile strength (hydrated: 2.1 ± 0.3 N vs. RAPA: 1.8 ± 0.2 N, CTL: 1.5 ± 0.2 N; P <0.05) and maintained structural integrity in both acidic (pH 1.0) and alkaline (pH 8.0) environments for 7 days. In vitro , drug-loaded sutures significantly inhibited HUVEC proliferation by 40% ( P = 0.0096) without inducing apoptosis. In vivo evaluations across venous, arterial, intestinal, gastric, and abdominal wall closures revealed that NEC-1 sutures markedly reduced foreign body reactions, exhibiting the smallest capsule area (0.12 ± 0.03 mm 2 vs. CTL: 0.35 ± 0.05 mm 2 ; P <0.0001) and 58% fewer CD68 + macrophages compared to controls ( P = 0.0015). All suture types achieved successful leak-free wound closures, with NEC-1 showing particularly strong suppression of neovascularization (CD31 + vessels: 12 ± 3 vs. CTL: 28 ± 5; P = 0.0001). The RAPA sutures also showed significant improvements over controls but were intermediate in performance between NEC-1 and uncoated CTL sutures. Mechanical testing confirmed that both drug-loaded variants (RAPA and NEC-1) maintained higher strength than CTL sutures under both dry and hydrated conditions, while histological analyses demonstrated progressive reductions in inflammatory markers (CD45 +, PCNA +, cleaved caspase 3 + cells) with drug-functionalized sutures.

CONCLUSION

Swim bladder-derived sutures demonstrate universal applicability, staged drug release, and significant reductions in inflammatory responses, offering a promising alternative for multitissue surgical repairs.

GRAPHIC ABSTRACT: The process of making suture and summarizing the cross-tissue analysis protocol. A: Surgical extraction and processing workflow. ① Tissue harvest from fish. ② The swim bladder undergoes decellularization treatment. ③ Microdissection into standardized strips. ④ The swim bladder is processed to create a drug-carrying, multiscene, absorbable biological suture. B: Fish swim bladder suture is used to stitch various organs. (i) Inferior vena cava and infrarenal abdominal aorta. (ii) Small intestine. (iii) Stomach. (iv) Abdominal wall.