The Preliminary Assessment of New Biomaterials Necessitates a Comparison of Direct and Indirect Cytotoxicity Methodological Approaches.

Background: Cytotoxicity testing is a primary method to establish the safety of biomaterials, e.g., biocomposites. Biomaterials involve a wide range of medical materials, which are usually solid materials and are used in bone regeneration, cardiology, or dermatology. Current advancements in science and technology provide several standard cytotoxicity testing methods that are sufficiently sensitive to detect various levels of cellular toxicity, i.e., from low to high. The aim was to compare the direct and indirect methodology described in the ISO guidelines UNE-EN ISO 10993-5:2009 Part 5.

Methods: Cell proliferation was measured using WST-1 assay, and cytotoxicity was measured using LDH test kit.

Results: The results indicate that the molecular surface of biomaterials have impact on the cytotoxicity and proliferation profile. Based on these results, we confirm that the indirect method does not provide a clear picture of the cell condition after the exposure to the surface, and moreover, cannot provide complete results about the effects of the material.

Conclusions: Comparison of both methods shows that it is pivotal to investigate biomaterials at the very early stages using both indirect and direct methods to access the influence of the released toxins and surface of the material on the cell condition.