Relative Protein Abundances and Biological Ageing in Whole Skeletal Elements

Establishing biological age is an integral part of forensic investigations, currently achieved through morphological methods with varying degrees of accuracy. Furthermore, biological ageing is much easier in juveniles than in adults, at which point traditional ageing methods struggle. Therefore, biomolecular approaches are considered of great interest, with several protein markers already recognized for their potential forensic significance. However, previous studies have typically relied on subsampling different parts of skeletal elements. Here, we attempt to evaluate the proteome of complete elements using a rat model. In the analysis of specimens spanning beyond adulthood (1 week to 1.5 years), we observed 729 unique proteins across 33 samples (three for each sex for each of the five (female) or six (male)), five of which represent newly identified proteins in relation to age estimation: vimentin, osteopontin, matrilin-1, apolipoprotein A-I, and prothrombin. Most of these follow the trend of decreasing abundance through age, with the exception of prothrombin that increases. We consider the combined use of these relative abundances, along with those of previously noted fetuin-A, biglycan, albumin, and chromogranin-A signatures, as being of potential value to the development of an age estimation tool worthy of further evaluation in forensic contexts.