Evaluation of Two Methods for Decellularizing Human Amniotic Membranes for Use in Tissue Engineering

Background: The human amniotic membrane (hAM) is widely used in tissue engineering due to its low immunogenicity and extracellular matrix (ECM) rich in structural proteins; in this context, decellularization aims to remove cellular components while preserving tissue integrity, and this study aimed to compare the effects of two enzymatic methods (trypsin and thermolysin). Methods: Human amniotic membranes obtained from placentas were divided into three groups: non-decellularized control, trypsin-treated, and thermolysin-treated. The membranes were treated with 0.25 trypsin-EDTA for 60 min at 37 °C, followed by incubation with Triton X-100 for 30 min at 37 °C, or with 125 µg/mL thermolysin for 9 min at 37 °C. Histological analysis with hematoxylin–eosin and semi-quantitative scoring assessed epithelial and stromal integrity, immunohistochemistry evaluated laminin α and fibronectin expression with quantitative image analysis, and uniaxial tensile testing measured mechanical properties; no preregistration numbers or animal models were reported. Results: Trypsin achieved more effective epithelial removal, whereas thermolysin caused greater stromal disruption; no statistically significant differences in laminin α or fibronectin expression were found among groups (p > 0.05), indicating preservation of key ECM components; both treatments reduced mechanical performance, with thermolysin decreasing early- and mid-path stiffness and trypsin reducing late-path stress and work density. Conclusion: Both enzymatic protocols preserved ECM composition but induced distinct structural and mechanical alterations, suggesting that method selection should balance efficient cell removal with preservation of structural and functional properties according to the intended application.