The impact of maceration on the 'Osteo-ome'; a pilot investigation

The bone proteome, i.e., the 'osteo-ome', is a rich source of information for forensic studies. There have been advances in the study of biomolecule biomarkers for age-at-death (AAD) and post-mortem interval (PMI) estimations, by looking at changes in protein abundance and post-translational modifications (PTMs) at the peptide level. However, the extent to which other post-mortem factors alter the proteome, including 'maceration' procedures adopted in human taphonomy facilities (HTFs) to clean bones for osteological collections, is poorly understood. This pilot study aimed to characterise the impact of these 'cleaning' methods for de-fleshing skeletons on bone biomolecules, and therefore, what further impact this may have on putative biomarkers in future investigations. Three specific maceration procedures, varying in submersion time (one week or two days) and water temperature (55 °C or 87 °C) were conducted on six bovid tibiae from three individual bovines; the proteome of fresh and macerated bones of each individual was compared. The maceration at 87 °C for two days had the greatest proteomic impact, decreasing protein relative abundances and inducing specific PTMs. Overall, these results suggest that routinely-employed maceration procedures are harsh, variable and potentially threaten the viability of discovering new forensic biomarkers in macerated skeletal remains. SIGNIFICANCE: For the first time, the application of bone proteomics in understanding maceration procedures was conducted to help address the risks for experimental confounding associated with this post-mortem cleaning technique. This pilot study demonstrates that recent advances in biomarker discovery for post-mortem interval and age-at-death estimation using bone proteomics has potential for confounding by differing and destructive bone-cleaning methods.