# In Vivo Biocompatibility Assessment of a Novel Cyanoacrylate–Polylactic Acid Hemostatic Patch

## TL;DR

A new CA + PLA hemostatic patch caused more long-term inflammation and scarring in rats compared to a commercial product and electrocautery.

## Contribution

First 5-month in vivo biocompatibility assessment of a novel CA + PLA hemostatic patch in a rat model.

## Key findings

- The CA + PLA patch caused a higher rate of abscesses and fibrosis compared to TachoSil® and electrocautery.
- TachoSil® showed reduced inflammation and better vascularization over time, unlike the CA + PLA patch.
- Foreign-body giant cells were significantly more common in the CA + PLA group than in the other groups.

## Abstract

Background and Objectives: Although cyanoacrylate–polylactic acid (CA + PLA) patches shorten the time to hemostasis after partial hepatectomy, their long-term biocompatibility remains uncertain. We compared the 5-month histopathological footprint of a novel CA + PLA patch (Study group) with a licensed fibrinogen/thrombin matrix (TachoSil® group) and electrocautery (Control group). Methods: Thirty-three male Wistar rats underwent a 3 × 1.5 cm hepatic segment resection and were randomized to the Control (n = 5), Study (n = 14), or TachoSil® (n = 14) group. The animals were sacrificed on postoperative day (POD) 50, 100, or 150. Blinded semiquantitative scoring (0–3) was used to capture inflammation intensity, and the number of neutrophils (PMNs), lymphocytes (Ly’s), isolated histiocytes, and foreign-body giant cells (FBGCs). Results: The proportions of animals in each group across the different sacrifice time points were homogeneous (χ2 = 4.34, p = 0.36). The median inflammation remained mild (2 [IQR 1–2]) in the Control and Study groups but lower in the TachoSil® group (1 [1–2], p = 0.47). The FBGC scores differed markedly (score ≥ 2: 64% in Study, 0% in Control, 14% in TachoSil®; p < 0.001). Fibrosis occurred almost exclusively in the Study group (79% vs. 0%; χ2 = 22.4, p < 0.001). Mature vessels were most frequently observed in the TachoSil® group (50%, aOR = 5.1 vs. Study, p = 0.04). Abscesses only developed in the Study group (29%, p = 0.046). Within the TachoSil® group, inflammation (ρ = −0.62, p = 0.019) and Ly infiltration (ρ = −0.76, p = 0.002) declined with time; no significant temporal trends emerged in the Study group. Conclusions: At the five-month follow-up, there was an exuberant foreign-body reaction, dense collagen deposition, and a higher abscess rate around the CA + PLA patch compared with both TachoSil® and cautery. Conversely, TachoSil® evolved toward a mature, well-vascularized scar with waning inflammation. These findings underscore the importance of chronic-phase evaluation before clinical adoption of new hemostatic biomaterials.