Different solutions used for submucosal injection influenced early healing of gastric endoscopic mucosal resection in a preclinical study in experimental pigs

BACKGROUND: We hypothesised that different solutions for submucosal injection may influence early healing of endoscopic mucosal resection (EMR). The aim of this study was to evaluate histological and immunological changes after EMR in experimental pigs. MATERIALS AND METHODS: Two parallel EMRs on the anterior and posterior wall of the gastric body were performed by means of the cap technique in 21 female pigs. A glycerol-based solution (anterior EMR) and hydroxypropyl methylcellulose solution (posterior EMR) were applied for submucosal injection. The animals were sacrificed 7 days later, and tissue sections of all EMRs were stained using combined trichrome. Computer image analysis was used for objective evaluation of elastic and collagen fibres content. Two-colour indirect immunophenotyping of blood and gastric samples were performed using mouse anti-pig monoclonal antibodies. RESULTS: The values of collagen fibre content 7 days after EMR were significantly higher in lesions after the use of solution A in comparison with solution B (2.10 ± 0.25% versus 1.57 ± 0.25%, p = 0.009). Concordant results were found in elastic fibres (3.23 ± 0.49% versus 2.93 ± 0.61%, p = 0.018). No systemic changes in major leukocyte subpopulations were found. In gastric tissue, lymphocyte subsets exhibited only minor changes. CD4(+) T-lymphocytes were increased in the healing tissue after EMR using solution A (17.08 ± 9.24% versus 9.76 ± 7.97%, p = 0.011). Significant increase of SWC3(+) leukocytes was observed after EMR using solution B (47.70 ± 25.41% versus 18.70 ± 12.16%, p = 0.001). CONCLUSIONS: The use of glycerol-based solution for submucosal injection was associated with more pronounced histological signs of early healing of EMRs compared with hydroxypropyl methylcellulose.