| Ultrasound now is widely used both in diagnosis and in therapy. As a new noninvasive local therapy, high intensity focused ultrasound (HIFU) therapy is gaining recognition from more and more doctors and patients. Previous studies revealed that low intensity pulsed ultrasound (LIPUS) had specific biological effects. The results of experiments in vitro and in vivo suggested that low intensity pulsed ultrasound could influence cell proliferation, promote protein synthesis, influence cytokine release and induce cell differentiation. LIPUS is used to accelerate fracture healing, to treat osteoradionecrosis and to repair epidermis after wound. But experimental investigations into the biological effects of LIPUS on skin fibroblast are quite scarce.This study was designed to investigate the changes in the cellular proliferation activities and the ability of collagen synthesis after LIPUS stimulation and screen out the optimal parameters of LIPUS to promote skin fibroblast proliferation, and provide reference for clinical use. We also explore the efficacy and safety of focused ultrasound in treatment of chronic eczema and neurodermatitis.PART I Screening of the opimal LIPUS parameters for skin fibroblast proliferationLIPUS of different frequency(1, 1.2, 1.7MHz)and four different intensities of each frequency was used to sonication the cultured human fibroblast cells. Under each frequency and intensity, the cells were randomly divided into 6 groups according to ultrasound exposure duration: 0 minute (the sham group), 5 minutes,10 minutes,20 minutes and 30minutes. 24 hours later, cell proliferation was examined, and the relative survival rate was calculated using MTT assay. Each test was repeated three times. After a comparison of the relative survival rate, we screened out the optimal parameters.Results: (1) As compared with the control group(P<0.05), the optical absorption value of cell activity in MTT assay increased significantly in the different frequency groups(1,1.2,1.7MHz) for 5and 10 minutes and the peak time is 10 imnutes . But the optical absorption value decreased with longer sonication time and the value decreased significantly in human skin fibroblasts with LIPUS sonication for more than 30 minutes (P<0.05). (2) The relative survival rate of the group 1MHz,0.1W/cm2 and 5 minutes was 1.195,and the 10 minutes group was 1.325; the peak relative survival rate was detected in the group with the LIPUS of 1MHz,0.1W/cm2 sonication for 10 minutes . 10004.22±743.53, which was 2.31 times of the sham group. A peak value was detected in the cell culture with LIPUS sonication for 10 minutes.But with longer sonication time, the value decreased.(2) The cell number in the S phase of the 5 minutes group was (13.84±1.77)%, which was a significant higher than the sham group(P<0.05); and the cell number in the G2/M phase was (19.64±2.88)%, which was reduced compared with the sham group. The peak changes were detected in the 10 minute group, where the cell number of the S phase was (20.56±3.56)% and the cell number in the G /M phase was (15.89±1.75)%. Both were significantly different as compared with the sham group.Conclusions: Sonication with LIPUS of 1MHz and 0.1W/cm2 in a limited time could promote DNA synthesis and collagen production of skin fibroblasts, and promote cell transition from G2/M phase to S phase, so fibroblast cell proliferation was promoted.PART III Clinical Study of ultrasound effect in the treatment of neurodermatitis and chronic eczemaA self-controlled clinical trial was conducted in 51 patients with neurodermatitis and 51 patients with chronic eczema. The treatment group was given focused ultrasound therapy, while the control group was managed by white Vaseline, applied externally twice a day. Symptom/sign scores and total scores were evaluated at the beginning of the treatment and one month after the initiation of the treatment. Results: All symptom/sign scores and total scores were significantly decreased 1 month later.Statistically significant difference was observed between the treatment group and the control group. In the treatment group, the cure rate and improvement rate for neurodermatitis patients were 2% and 52.9% respectively ; For chronic eczema patients the cure rate and improvement rate were 8% and 54.9% respectively. The cure rate and improvement rate of the treatment group were significantly higher than those of the control group(P〈0.05〉. No statistically significant difference in efficacy was observed between the different severity(the total scores>9 or≤9)neurodermatitis and chronic eczema patients. Pruritus was significantly improved after ultrasound treatment: 90.2% of chronic eczema patients and 80.4% of neurodermatitis patients were benefited with pruritus disappearance or obvious alleviation.The side effect was zero.Conclusion: Neurodermatitis and chronic eczema could be effectively treated with focused ultrasound therapy. This approach appears to be a new physical local treatment, although further studies are still needed. |
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