Material/methods

Tissue sampling and preparation

Spleen samples from 53 adult cadavers (14 females, 39 males) were retrieved at the Institute of Legal Medicine, University Medical Center Hamburg-Eppendorf during forensic autopsies. The Ethics Committee of the Hamburg Medical Association (reference number: 2023-101023-BO-ff) approved the study. The ages at death of the cadavers ranged from 23 to 90 years with a mean (M) and standard deviation of 64 ± 16 years. The PMI was 208 ± 97 h, with a minimum and maximum of 42 and 518 h. The exact PMI was unknown in two of the mechanically analyzed cases. A rectal temperature of at least 30 °C upon admission to the cooling unit of the morgue and structural integrity of the organ at autopsy were defined as inclusion criteria. The spleen weight at autopsy was 192 ± 117 g with a range of 50 to 600 g. Additionally, spleen samples from four pediatric cases were tested. The age at death, cause of death, spleen weight, sex, and PMI for the pediatric cases are presented in the Results section (Table 3), together with the measured rheological properties. For the rheometer tests, circular cylindrical samples were punched from the splenic pulp using a commercial biopsy punch with a diameter of 10 mm; depth: 5 mm; Fig. 1). Following this, all samples were tested within two hours after the preparation and stored in sealed plastic containers at 4 °C until then.

Fig. 1: Representative images of the punching process are shown. (A) The sample is punched at the autopsy table from a rather muddy spleen with a commercial biopsy punch. (B) The punched sample is shown before height adaptation