Cytokinetics of epidermic cells in skin from human cadavers. II. Dependency on sex, age, and site

The time-course analysis of gene expression during wound healing in mouse skin

RNA analysis has been applied to forensic work to determine wound age. We investigated mRNA expression using quantitative RT-PCR of ten genes, including c-fos, fosB, mitogen-activated protein kinase phosphatase-1 (MKP-1), CD14, chemokine (C-C motif) ligand 9 (CCL9), placenta growth factor (PlGF), mast cell protease-5 (MCP-5), growth arrest specific 5 (Gas5), beta-2 microglobulin (B2M) and major urinary protein-1 (MUP-1), in terms of repair response in adult mice. The expression level of c-fos, fosB and MKP-1 transcripts increased drastically, peaked within 1h, and that of the CD14 and CCL9 transcripts peaked from 12 to 24h. An increase in PlGF and MCP-5 mRNA appeared on about day 5. Gas5, B2M and MUP-1 transcripts showed no significant change. Each gene had differentially expressional patterns with time-course. Our result implied that the observation of the 7 genes in wounded skin could serve to aid in the accurate diagnosis of wound age.

RNA and DNA synthesis of epidermal basal cells after wounding. Comparison of vital and postmortem investigations

Incision wounds were made on both of the pinnae of each rat, and two biopsies from both the ears were taken for examination after different survival times of the wounds. Two biopsies were taken from each ear, four from each animal, two intravitally and two postmortem after 24 hours storage at 8 degrees C. One each of the intravital and one each of the postmortem biopsies were prepared and evaluated for quantification of RNA and DNA synthesis rate using an in vitro incorporation model with 3H-cytidine and bromodeoxyuridine (BrdU) as markers. The intravital specimens showed a significant increase in 3H-cytidine incorporation in the basal cell layer after survival times of 10 to 24 hours. No increase in the rate of RNA synthesis in the basal cell layer as a function of wound age was seen in postmortem specimens. In both intravital and postmortem biopsies the labelling indices after BrdU exposition increased significantly in the period from 32 to 60 hours post-injury. This suggest that DNA synthesis induced during life continues after death. Applied to forensic practice, these findings point to the possibility of determining the vitality of a wound in postmortem tissue. The RNA synthesis, obviously, precedes the DNA synthesis after mechanical trauma.

Temporal course of intravital and postmortem proliferation of epidermal cells after mechanical injury. An immunohistochemical study using bromodeoxyuridine in rats

The temporal course of epidermal basal cell proliferation in the wound of the pinna of rats was studied using bromodeoxyuridine (BrdU) immunohistochemistry. Following incisional wounding, the animals were sacrificed at intervals ranging from 0 hours to 32 days. Two biopsies were taken from each animal, one intravitally and one postmortem after 24 hours storage at 8 degrees C. Specimens were incubated in a solution containing BrdU and embedded in paraffin. BrdU expression was demonstrated by a monoclonal antibody against BrdU. In both intravital and postmortem biopsies, the labelling indices increased significantly in the period from 32 to 60 hours post-injury. This suggests that DNS synthesis induced during life continues after death. Applied to forensic practice, the present findings point to the possibility of determining the vitality of a wound in postmortem tissue.

RNA kinetics at the wound margins

The in vitro incorporation rate of 3H cytidine was determined by autoradiography in vital specimens taken from cut wounds in the outer ear of rats and evaluated by means of a Quantimet 920. Seven rats in each group were allowed to survive for the same periods of time between 0 and 60 hours. The following findings were observed: after 10 hours survival time the cytidine incorporation rate in the basal cells increased significantly, while remaining unchanged in all other skin layers. The relationship between the higher RNA synthesis rate and the increase in DNA synthesis--particularly in the basal cell layer--is discussed.