Biocompatibility of heparin-coated PLLA-chitosan patch potentially usable for large blood vessel reconstruction: A Wistar rat histological study

Introduction: Stroke remains a leading cause of disability and death globally, with carotid stenosis as a major contributor. Carotid endarterectomy with patch angioplasty reduces restenosis risk, but current patch materials often lack biocompatibility and biodegradability. This study introduces a novel vascular patch composed of poly-L-lactic acid (PLLA) and chitosan, coated with heparin, designed to promote tissue integration and safe degradation. Method: A true experimental in vivo study was conducted using 54 Wistar rats, divided into three groups: (1) PLLA scaffold (Group K1/K2), (2) PLLA-chitosan scaffold (Group P1/P3), and (3) PLLA-chitosan with heparin coating scaffold (Group P2/P4). Histological analyses at 14 and 56 days post-implantation evaluated inflammatory response, fibrous capsule formation, and angiogenesis. Statistical analysis included ANOVA, T-test, and Mann–Whitney U test (significance p < 0.05). Results: At 14 days, inflammatory cell infiltration differed significantly among groups (p = 0.019), with the PLLA-chitosan patch showing the lowest inflammatory cell count. By 56 days, inflammation had subsided in all groups (p = 0.989). Initial fibrous capsule thickness at 14 days was higher in the heparin-coated group and differed significantly among groups (p = 0.019), but by 56 days all groups showed stable fibrous encapsulation with no significant differences (p = 0.916). All implants supported neovascularization, with evidence of new blood vessel formation (angiogenesis) around the patch materials. No excessive fibrous tissue formation or cytotoxic effects were observed in any group. Conclusion: The heparin-coated PLLA-chitosan patch displayed good biocompatibility, modulating inflammation, and supporting neovascularization. These findings suggest its potential as a vascular graft for large vessel reconstruction, though further long-term studies are needed.