Osteogenic response to clinically used gelatin-based hemostatic materials: <i>in vitro</i> and <i>ex vivo</i> evidence of material-dependent effects

The clinical use of topical hemostatic agents has become increasingly widespread. While these agents primarily serve to control bleeding, their direct contact with bone and surrounding tissues raises concerns about biological compatibility and potential interference with bone healing and regeneration. Given their growing use in osseous surgical procedures, it is critical to characterize and compare the osteogenic properties of these materials. This study evaluated four commercially available gelatin-based hemostatic sponges: Hemospon®, Clinix®, Gelatamp®, and Octocolagen®, for their osteogenic potential. Leachables derived from each sponge were prepared according to ISO 10993-12:2021 guidelines and tested at 12.5% and 50% concentrations in<i>in vitro</i>assays using human osteoblastic populations. Assessed parameters included metabolic activity, proliferation, osteogenic gene expression, alkaline phosphatase (ALP) activity, and extracellular matrix production. Additionally, intact sponges were directly applied to bone defects in an<i>ex vivo</i>organotypic bone culture model, enabling the tissue characterization within a physiologically relevant environment. Results demonstrated marked material-dependent differences. Gelatamp® significantly enhanced osteogenic gene expression, ALP activity, and matrix production<i>in vitro</i>, and promoted mature collagen deposition<i>ex vivo</i>. Hemospon® also showed favorable, though more limited, effects. Octocolagen® exhibited a neutral biologically profile, while Clinix® consistently impaired osteoblastic activity, gene expression, and extracellular matrix formation in both models. These findings demonstrate that gelatin-based hemostatic agents are not biologically equivalent. Material composition and processing influence their regenerative performance, underscoring the need for informed selection when used in bone-contact surgical applications.