The influence of low-intensity broadband ultrasound on skin regenetation in an experiment

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Department of Health Care education and physical recreation Dragomanov Ukrainian State University

The influence of low-intensity broadband ultrasound on skin regenetation in an experiment

Marchenko Alexander Timofeevich PhD, Deputy Director for Research Techno-Med Ukraine, Kuzmenko Alexander Petrovich PhD, Associate Professor

Ukraine

Summary

Comparative studies of the effects of low-intensity pulsed ultrasound (LIPUS) and low- intensity broadband ultrasound (UMUS) on the rate of healing of standard wounds in Balb mice were conducted. It was found that the use of UMUS was accompanied by a significant reduction in the time of complete regeneration of the wound surface compared to the control and the use of LIPUS, which was confirmed by the results of histological studies.

Key words: low-intensity broadband ultrasound (UMUS), low-intensity pulsed ultrasound (LIPUS), wound regeneration, regeneration of skin wounds.

Introduction

The study of the processes of recovery of traumatic lesions is one of the urgent tasks of modern restorative medicine. The use of ultrasonic vibrations in this area has been known for a long time. But only in recent years in biology and medicine has the method of accelerating the healing of wound surfaces, reducing inflammatory reactions in the affected area and significantly accelerating reparative processes in bone tissue using the method of Low-Intensity Pulsed Ultrasound (LIPUS) begun to be widely studied and applied [1-3]. This type of ultrasound can promote skeletal muscle functional repair and skin healing and restoration, but the effectiveness of these processes is insufficient for practical applications [4-6]. It is of interest to compare the action of the narrowband LIPUS signal, which is potentially capable of transmitting relatively small volumes of influencing information to the treatment area, with recently described Ultra-wideband Micromechanical Impact Bursts (UMI Bursts) signals [7], capable of transmitting many orders of magnitude large volumes of impact information to the treatment area. Therefore, it is relevant to compare the results of the effects of narrowband LIPUS and ultra-wideband UMI Burst ultrasound (abbreviated as UMUS) on the healing of extensive animal wounds.

Material and method

The studies were carried out on 40 mice of the BALB line of the vivarium of the R.E. Kavetsky Institute of Experimental pathology, Oncology and Radiobiology of the NAS of Ukraine. The animals were kept in a certified vivarium. All studies were carried out on animals in accordance with the requirements of the regional Committee on the Ethics of Working with Experimental Animals and in compliance with the rules for working with experimental animals. All animals had their dorsal hair depilated and, under anesthesia, a linear skin wound (17-18 mm) was inflicted with a scalpel. This size of the wound is determined by the size of the ultrasound transducer. Anesthesia was administered intraperitoneally at the rate of 40 mg etaminal sodium per 1 kg of animal weight. pulsed regeneration wound

An SDG 2082 X generator from Siglent company was used as a source of electrical signals for excitation of ultrasonic transducer. Ultra-wideband conversion of generator signals into ultrasonic vibrations in the frequency band 1-7 MHz was carried out by a 15-mode piezoceramic transducer with overlapping vibration modes and polarization normal to the radiating surface. Transducer has the diameter 20 mm and maximum thickness 3 mm. Copper electrodes were applied to the working and back sides of the converter. The front surface was protected by a wear-resistant multilayer coating made of layers of titanium, stainless steel and titanium nitride. The effects of LIPUS and UMUS were carried out directly on the wound surface through a layer of ultrasonic gel Aqua Ultra Basic UBQ 5000 Ultragel (Hungary).

The animals were divided into groups, each of which included 10 mice. The following modes of exposure were used in the studies: group 1 - control (no exposure); Group 2 - exposure to the wound surface with low-intensity ultra- wideband UMUS ultrasound 0.001 mW/cm2; Group 3 (LIPUS) - exposure 30 mW/cm2 .Ultrasound exposure in all groups was 1 0 minutes daily for 1 0 days.

Table 1 Parameters of signals

Regeneration of the wound surface was assessed by daily measurement of the linear dimensions of the wound using a Hoegert stainless steel caliper and by morphological studies. Material was collected for histological studies after 10 exposure sessions. The preparations were prepared according to standard methods using hematoxylin-eosin staining. Analysis of the obtained histological preparations was carried out using an Axiostar Plus microscope from Zeiss (Germany).

Statistical analysis was carried out using Student's t test with preliminary testing of the hypothesis about the normal distribution of a random variable using the Kolmogorov-Smirnov test using the STATISTICA 6.0 software package (StatSoft).

Results

As a result of the studies, it was found that in animals in the control group, the linear dimensions of the wound did not change for 2 days after its application, apparently due to the concomitant inflammatory reaction. For animals exposed to ultrasound, such a slowdown in regenerative processes was not observed, which may indicate the absence of pronounced inflammation in the area of the wound (Fig. 1).

Fig. 1. Dynamics of mouse skin regeneration after exposure to LIPUS and UMUS.

Already from 4 days after the injury to the skin, there was a statistically significant decrease in the wound surface in the UMUS group compared to the other study groups (P<0.05). The rate of regenerative processes in the other groups during these periods did not differ significantly from each other. From days 5 to 6, there was also. Some delay in healing in the control and 2 experimental groups (LIPUS and UMUS).

However, this effect was not observed in the UMUS group. The absence of such a delay in the repair of skin damage when using ultra-widedband micromechanical effects of weaker ultrasound may indicate an acceleration of wound healing processes. By 10 days after the injury, complete epithelization of the wound surface was observed in mice of the UMUS group. In other experimental and control groups, the wound sizes ranged from 2 to 4 mm.

Thus, the use of low-intensity ultra-wideband ultrasound micromechanical bursts with micro intensity of exposure to radiation power can lead to a significantly more pronounced stimulation of regenerative processes than LIPUS, thereby accelerating the healing of the skin in laboratory animals.

Morphological studies carried out on the 10th day after the skin injury showed the following. In the dermal layer of the skin of mice in the control group, there was an absence of stratified squamous epithelium, large confluent foci of necrosis almost to the level of muscle tissue, which were surrounded by an inflammatory infiltrate and symptoms of edema in the fatty layer (Fig. 2).

Fig. 2. Control. Coloring hematoxylin-eosin. Mag. x100

Fig. 3. LIPUS. Coloring hematoxylin-eosin. Mag. x 100

The skin of animals with linear trauma after 10 exposures to the LIPUS regime was characterized by initial, mild epithelization, residual signs of necrobiotic changes, and restoration of connective tissue. In adjacent areas the stratified epithelium is dense. Slight diffuse lymphocytic infiltration is observed (Fig. 3). The skin of mice with linear injury after 1 0 sessions of the UMUS mode is characterized by the fact that there is a complete restoration of stratified squamous epithelium, no signs of necrosis, as well as restoration of the dermis and adipose tissue layers. The restoration of blood vessels can be observed (Fig. 4).

Thus, the research results showed that the use of microintensive ultrabroadband ultrasound UMUS with a radiation intensity of 0.001 mW/cm2 is accompanied by a pronounced stimulation of the regenerative processes of the wound surface of the skin in Balb mice. The observed effect of accelerating regeneration was observed when the radiation intensity was reduced by an order of magnitude. The effect of accelerating regeneration was confirmed not only by macroscopic studies in dynamics, but also by microscopic histological observations.

Fig. 4. UMUS. Coloring hematoxylin-eosin. Mag. x100.

References

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