Significance of chondrocyte viability in postmortem interval assessments and chondrocyte viability assay

Determination of the postmortem interval (PMI) is one of the most challenging problems in forensic medicine. The main aim of this study was to determine the dynamics of the decrease in the fraction of viable chondrocytes excluded from the donors' knees for PMI determination. The other aim was to find an appropriate method for chondrocyte viability assay. We analyzed osteochondral cylinders from 35 donors (28 males and 7 females), aged 44 to 90 years, whose bodies were stored in refrigerators at temperature of 8 ± 2 °C, during the period from 4 to 83 days postmortem. The proportion of viable chondrocytes was determined by flow cytometry (FC) and cell viability analyzer (CVA). For FC we used RedDot™1 to mark all chondrocytes with nuclei (method FCN) and 7-AAD, to distinguish live/dead cells (method FCC) among RedDot™1 positive cells. Results revealed that chondrocytes from the knee cartilage can be found alive after more than two months postmortem. We observed that even in controlled temperatures and environment, the predicted interval for PMI is too wide for this method to be used in daily forensic practice, likely due to the relatively small number of donors considered in our study, and other unknown factors that affect the viability of chondrocytes in dead bodies. This could be verified with a larger number of donors followed over a longer period. FCC is a slightly superior method over CVA and FCN in terms of its ability for PMI determination.