OBJECTIVETo analyze the potential mechanism of preventive and therapeutic effects of (90)Sr on hypertrophic scar, and to observe its clinical effect.

METHODSFibroblasts isolated from human hypertrophic scar were cultured in vitro and radiated by (90)Sr with the dose varying from 0 Gy (control group) to 5 Gy (LD group), 10 Gy (MD group), and 15 Gy (HD group). The cell cycle and apoptosis rate were determined by flow cytometry at post radiation hour (PRH) 24, 48, and 72. The concentration of type I collagen in cell supernatant was detected by enzyme-linked immunosorbent assay (ELISA). Therapeutic effects of (90)Sr radiation were evaluated among 348 patients with hypertrophic scars, 40 patients with keloids, and 114 patients for scar prevention after surgical operation. The number of fibroblasts after HE staining was compared among normal skin tissue, hypertrophic scar, and hypertrophic scar treated with (90)Sr radiation. Data were processed with one-way analysis of variance and q test.

RESULTS(1) Apoptotic rates in MD and HD groups at PRH 48 were higher than those at PRH 24, and the apoptotic rate was similar between MD group and HD group at PRH 72. Apoptotic rate in LD group at PRH 48 was significantly higher than that at PRH 24, but it decreased rapidly at PRH 72, which was significantly lower than those in MD and HD groups (with F values all equal to 916.711, P values all below 0.01). (2) At PRH 24, cell ratios of each phase in LD and HD groups were similar, and cell ratio of S phase in HD group [(48.1 ± 1.0)%] was higher than those in the other three groups (with F values all equal to 200.277, P values all below 0.01). At PRH 72, cell ratio of S phase in MD and HD groups was respectively (85.7 ± 5.2)%, (73.0 ± 8.4)%, implying that cells were blocked in S phase, and the values were all higher than those in control and LD groups (with F values all equal to 111.105, P values all below 0.01). (3) At the same time point, the concentration of type I collagen decreased along with the increase of radiation dose (with F values from 5044.449 to 8234.432, P values all below 0.01). With the same radiation dose, the concentration of type I collagen increased along with prolongation of time (with F values from 333.395 to 2973.730, P values all below 0.01). (4) Clinical observation showed the (obvious) effective rate of radiation for pathological scars and that for scar prevention after surgical operation added up to 88.45%. The number of fibroblasts per 200 times visual field in patients after (90)Sr radiation (86 ± 20) was less than that in patients without treatment [(198 ± 65), F = 208.405, P < 0.05].

CONCLUSIONSThe effect of (90)Sr radiation on fibroblasts and extracellular matrix can contribute to inhibition of scar formation, and the clinical effect is significant.