Human Bone Proteomes before and after Decomposition: Investigating the Effects of Biological Variation and Taphonomic Alteration on Bone Protein Profiles and the Implications for Forensic Proteomics

Bone proteomic studies
using animal proxies and skeletonized human
remains have delivered encouraging results in the search for potential
biomarkers for precise and accurate post-mortem interval (PMI) and
the age-at-death (AAD) estimation in medico-legal investigations.
The development of forensic proteomics for PMI and AAD estimation
is in critical need of research on human remains throughout decomposition,
as currently the effects of both inter-individual biological differences
and taphonomic alteration on the survival of human bone protein profiles
are unclear. This study investigated the human bone proteome in four
human body donors studied throughout decomposition outdoors. The effects
of ageing phenomena (in vivo and post-mortem) and
intrinsic and extrinsic variables on the variety and abundancy of
the bone proteome were assessed. Results indicate that taphonomic
and biological variables play a significant role in the survival of
proteins in bone. Our findings suggest that inter-individual and inter-skeletal
differences in bone mineral density (BMD) are important variables
affecting the survival of proteins. Specific proteins survive better
within the mineral matrix due to their mineral-binding properties.
The mineral matrix likely also protects these proteins by restricting
the movement of decomposer microbes. New potential biomarkers for
PMI estimation and AAD estimation were identified. Future development
of forensic bone proteomics should include standard measurement of
BMD and target a combination of different biomarkers.