Evaluating Bioassays for the Determination of Simvastatin's Osteogenic Activity: A Systematic Review.

Abstract

Objective: Osteogenic differentiation is a complex process, and its analysis requires several biomarkers. Allied with this, there are no standardized bioassays to monitor the activity of simvastatin in osteogenesis in vitro. Therefore, identifying the most efficient and sensitive bioassays may enhance the quality of in vitro studies, bridging the gap with in vivo findings, saving time and resources, and benefiting the community. This systematic review aimed to determine the most efficient bioassay for simvastatin's osteogenic activity in vitro, in terms of sensitivity.

Materials and methods: In vitro studies evaluating undifferentiated mesenchymal cells treated with simvastatin were considered eligible. References were selected in a two-phase process. Electronic databases and the grey literature were screened up to September 2023. The Office of Health Assessment and Translation (OHAT) tool was used to assess the risk of bias. Certainty in cumulative evidence was evaluated using the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) criteria. Data were analyzed considering extracellular matrix mineralization, alkaline phosphatase, and the expression of potential target genes, such as bone morphogenetic protein-2 (BMP-2), collagen type I, Runt-related transcription factor 2, osterix, osteocalcin, and osteopontin.

Results: Fourteen studies were included. A "probably low" or a "definitely low" risk of bias was assigned to the included studies. The simvastatin concentration ranged from 0.1 nM to 10 µM. Considering a minimum 4-fold increase, simvastatin caused robust mineralization of the extracellular matrix in four studies (4.0-, 4.4-, 5.0-, and 39.5-fold). Moreover, simvastatin substantially increased BMP-2 expression in mesenchymal cells in three studies (4-, 11-, and 19-fold).

Conclusion: Therefore, mineralization of the extracellular matrix and BMP-2 expression in mesenchymal cells are the most efficient bioassays for determining the osteogenic activity of simvastatin in vitro (high certainty level). These findings provide a standardized approach that can enhance the reliability and comparability of in vitro studies, bridging the gap with in vivo research and optimizing resources in the field of bone regeneration.