An "up, no change, or down" system: Time-dependent expression of mRNAs in contused skeletal muscle of rats used for wound age estimation.

The combined use of multiple markers is considered a promising strategy in estimating the age of wounds. We sought to develop an "up, no change, or down" system and to explore how to combine and use various parameters. In total, 78 Sprague Dawley rats were divided randomly into a control group and contusion groups of 4-, 8-, 12-, 16-, 20-, 24-, 28-, 32-, 36-, 40-, 44-, and 48-h post-injury (n=6 per group). A contusion was produced in the right limb of the rats under diethyl ether anesthesia by a drop-ball technique; the animals were sacrificed at certain time points thereafter, using a lethal dose of pentobarbital. Levels of PUM2, TAB2, GJC1, and CHRNA1 mRNAs were detected in contused muscle using real-time PCR. An up, no change, or down system was developed with the relative quantities of the four mRNAs recorded as black, dark gray, or light gray boxes, representing up-, no change, or down-regulation of the gene of interest during wound repair. The four transcripts were combined and used as a marker cluster for color model analysis of each contusion group. Levels of PUM2, TAB2, and GJC1 mRNAs decreased, whereas that of CHRNA1 increased in wound repair (P<0.05). The up, no change, or down system was adequate to distinguish most time groups with the color model. Thus, the proposed up, no change, or down system provide the means to determine the minimal periods of early wounds.