[Effects of myrrh extract on proliferation and collagen mRNA expression of human fibroblasts in vitro].

Objective: To observe the effects of myrrh extract on biological characteristics of human dermal fibroblasts (Fb), and to explore its possible mechanisms in promoting wound healing.

Methods: Normal Fb was isolated from human foreskin tissue and cultured in vitro. The third to fifth passages of Fb were used in the experiment. (1) Fb were planted onto 96-well plate and divided into control group, and 1 × 10(-4), 1 × 10(-3), 1 × 10(-2), 1 × 10(-1), 1, 10, 1 × 10(2) g/L myrrh water extract groups and myrrh ethanol extract groups according to the random number table. Fb in control group were cultured with DMEM medium containing 0.25% calf serum (briefly called low-concentration serum medium), and those in various concentrations of myrrh water extract and myrrh ethanol extract groups respectively with low-concentration serum medium containing corresponding concentration of 2 kinds of myrrh extract. After being cultured for 48 h, cell morphology was observed with inverted-phase contrast microscope, and Fb proliferation activity (denoted as absorbance value) was determined with MTT method. (2) Fb were respectively planted into flasks and dishes and divided into two groups according to the random number table. Fb in control group were cultured with low-concentration serum medium, and that in 1 g/L myrrh water extract group with low-concentration serum medium containing 1 g/L myrrh water extract. After being cultured for 72 h, Fb cell cycle and the type I and III collagen mRNA expression were respectively determined by flow cytometry and real-time fluorescent quantitative PCR. Data were processed with LSD-t test.

Results: (1) Fb in all groups grew in long-spindle shape, but the cell fusion was much obvious in 1 g/L myrrh water extract group than in control group. Fb absorbance value in 1 × 10(-3), 1 × 10(-2), 1 × 10(-1), 1, 10 g/L myrrh water extract groups was respectively 0.378 ± 0.032, 0.402 ± 0.007, 0.390 ± 0.038, 0.453 ± 0.036, 0.390 ± 0.037, all higher than that in control group (0.332 ± 0.044, with t value respectively 2.24, 2.93, 2.69, 5.73, 2.71, P values all below 0.05). Compared with that in control group, Fb absorbance value in 1 × 10(-4) g/L myrrh water extract group was not statistically different (0.312 ± 0.048, t = 2.84, P > 0.05), while that in 1 × 10(2) g/L myrrh water extract group was significantly lower (0.154 ± 0.009, t = 7.17, P < 0.05). Fb absorbance values in 1 × 10(-3), 1 × 10(-1), 1, 10, 1 × 10(2) g/L myrrh ethanol extract groups were significantly lower than that in control group (with t values from 2.30 to 24.79, P values all below 0.05). (2) Compared with those in control group [(82.2 ± 7.9)% and (13.3 ± 2.3)%, (4.5 ± 0.8)%], the percentage of cells in G0/G1 phase in 1 g/L myrrh water extract group was obviously decreased [(74.3 ± 6.3)%, t = 6.77, P < 0.05], while those in S and G2/M phases increased [(16.6 ± 3.4)%, (9.1 ± 1.6)%, with t value respectively 7.53, 6.34, P values below 0.05]. Compared with those in control group (1.00 ± 0.05, 1.00 ± 0.06), the mRNA level of collagen III in 1 g/L myrrh water extract group was significantly up-regulated (1.38 ± 0.12, t = 3.81, P < 0.01), while that of collagen I was not statistically different (0.89 ± 0.08, t = 1.17, P > 0.05).

Conclusions: Myrrh water extract can notably promote the proliferation of Fb, accelerate the cell cycle of Fb, and up-regulate the mRNA expression of type III collagen in Fb, which may be related to its mechanisms in promoting wound healing.