Low-Magnitude High-Frequency Vibration Accelerated the Foot Wound Healing of n5-streptozotocin-induced Diabetic Rats by Enhancing Glucose Transporter 4 and Blood Microcirculation

Prevention of bone deterioration by whole-body vibration in a rat model of pre-type 2 diabetes

OBJECTIVES

To examine effects of whole-body vibration (WBV) on bone properties in pre-type 2 diabetes mellitus (T2DM) rats.

METHODS

Six-week-old male Hos:ZFDM-Lepr fa, fa/fa (DM) and Hos:ZFDM-Leprfa,fa/+ (CON; untreated non-DM) rats were used in the experiments. Half of DM rats were subjected to WBV (45 Hz, 0.5 g, 15 min/day, 5 days/week) for 8 weeks (WBV group), and the other half was not (DM group).

RESULTS

Bone mass, trabecular bone microstructure (TBMS), and cortical bone geometry (CBG) parameters were worse in the DM and WBV groups compared with the CON group. Maximum load was significantly decreased in the DM group compared with the CON group, and the break point was significantly higher in the WBV group compared with the DM group. Serum levels of bone specific alkaline phosphatase were significantly lower in the WBV group compared with the CON group. Glycemic control was not worse in the WBV group compared with the DM group, but not the same levels as the CON group.

CONCLUSIONS

These findings suggest that WBV can potentially delay the decrease in maximum load, although it does not prevent the deterioration of bone mass, TBMS, and CBG parameters.

Local low-frequency vibration accelerates healing of full-thickness wounds in a hyperglycemic rat model

AIMS/INTRODUCTION

Local low-frequency vibration (LLFV) promotes vasodilation and blood flow, enhancing wound healing in diabetic foot ulcers with angiopathy. However, vibration-induced vasodilation does not occur, owing to chronic hyperglycemia and inflammation. We hypothesized that LLFV improves glycometabolism and inflammation, leading to vasodilation and angiogenesis in diabetic wounds. Therefore, this study investigated the effect of LLFV on wound healing in hyperglycemic rats, primarily focusing on glycometabolism, inflammation, vasodilation, and angiogenesis.

MATERIALS AND METHODS

Streptozotocin-induced hyperglycemic Sprague-Dawley rats were used in this study. We applied LLFV to experimentally-induced wounds at 50 Hz and 0, 600, 1,000 or 1,500 mVpp for 40 min/day from post-wounding days (PWD) 1-14.

RESULTS

The relative wound areas in the 600 and 1,000 mVpp groups on PWD 5-7 were significantly smaller than those at 0 mVpp. The expression of Glo-1 (1,500 mVpp) and Slc2A4 (1,000 and 1,500 mVpp) was upregulated on PWD 4 and 14, respectively. However, there was no difference in methylglyoxal expression levels in any group until PWD 14. At 1,000 mVpp, the expression of Tnfa on PWD 4, and that of Ptx3 and Ccl2 on PWD 14 was downregulated. Furthermore, the M1/M2 macrophage ratio was considerably decreased on both days. The expression of Nos3, Vegfa and vascular endothelial growth factor A was upregulated on PWD 4. In addition, vasodilation and angiogenesis were more obvious on PWD 14 with 1,000 mVpp.

CONCLUSIONS

The results suggest that LLFV promotes wound healing, improves glycometabolism and inflammation, and enhances vasodilation and angiogenesis in hyperglycemic wounds.

Guard against internal and external: An antibacterial, anti-inflammation and healing-promoting spray gel based on lyotropic liquid crystals for the treatment of diabetic wound

The diabetic wound is a prevalent and serious complication of diabetes, which easily deteriorates due to susceptibility to infection and difficulty in healing, causing a high risk of amputation and economic burden to patients. Bacterial infection, persistent excessive inflammation, and cellular and angiogenesis disorders are the main reasons for the difficulty of diabetic wound healing. In this study, glycerol monooleate (GMO) was used to prepare lyotropic liquid crystal hydrogel (LLC) containing the natural antimicrobial peptide LL37 and carbenoxolone (CBX) to achieve antibacterial, anti-inflammation, and healing promotion for the treatment of diabetic wounds. The shear-thinning properties of the LLC precursor solution allowed it to be administered in the form of a spray, which perfectly fitted the shape of the wound and transformed into a gel after absorbing wound exudate to act as a wound protective barrier. The faster release of LL37 realized rapid sterilization of wounds, controlled the source of inflammation, and accelerated wound healing. The inflammatory signaling pathway was blocked by the subsequently released CBX, and the spread of the inflammatory response was inhibited and then further weakened. In addition, CBX down-regulated connexin (Cx43) to assist LL37 to promote cell migration and proliferation better. Combined with the pro-angiogenic effect of LL37, the healing of diabetic wounds was significantly accelerated. All these advantages made LL37-CBX-LLC a promising approach for the treatment of chronic diabetic wounds.

Muscle-targeted nanoparticles strengthen the effects of small-molecule inhibitors in ameliorating sarcopenia

Background: Sarcopenia is an aging-related degeneration of muscle mass and strength. Small-molecule inhibitor SW033291 has been shown to attenuate muscle atrophy. Targeted nanodrug-delivery systems can improve the efficacy of small-molecule inhibitors. Methods: The skeletal muscle cell-targeted nanoparticle was called AP@SW033291, which consisted of SW033291, modular peptide ASSLNIAGGRRRRRG and PEG-DSPE. Nanoparticles were featured with particle size, fluorescence emission spectra and targeting ability. We also investigated their effects on muscle mass and function. Results: The size of AP@SW033291 was 125.7 nm and it demonstrated targeting effects on skeletal muscle; thus, it could improve muscle mass and muscle function. Conclusion: Nanoparticle AP@SW033291 could become a potential strategy to strengthen the treatment effects of small-molecule inhibitors in sarcopenia.

Vascular response to the microcirculation in the fingertip by local vibration with varied amplitude

Objectives: We investigated the effect of local vibration intensity on the vascular response to the microcirculation of the finger. Materials and methods: We performed hand-transmitted vibration experiments combined with laser Doppler flowmetry (LDF) to measure the blood perfusion signals of fingertips in the vibrated hand and the contralateral middle finger under the same frequency and different amplitude vibration, and to analyze the changes of microcirculatory blood perfusion levels in the fingers, and to investigate the effects of vibration stimulation on the endothelial, neural and myogenic regulatory frequency ranges of fingertips based on wavelet analysis. Furthermore, the transparent silicone films were fabricated and cultured with vascular endothelial cell (EC), which will undergo the local vibration with varied amplitude. And the expression of inflammatory factors was detected in the ECs. Results: Low-frequency vibration leads to a decreased blood flow in fingertip, and the degree of reduction in fingertip blood flow increases as the amplitude gradually increases, and the period required for blood flow to return to normal level after hand-transmitted vibration gradually increases. The decrease in blood flow is more pronounced in the vibrating hand than in the contralateral hand. In addition, nuclear factor-κB (NF-κB) expression increased significantly with the increase of vibration amplitude. Conclusion: High amplitude vibrations caused the inflammatory reaction of ECs which will lead to the altered endothelial regulatory activity. The endothelial regulatory activity is closely related to the blood perfusion in the microcirculation.

Therapeutic Approach of Whole-Body Vibration Exercise on Wound Healing in Animal Models: A Systematic Review

Human skin wounds pose a gathering threat to the public health, carrying an immense epidemiologic and financial burden. Pharmacological and non-pharmacological (NP) treatments have been proposed to the management of wound healing. Physical exercise is a strong NP intervention considered for patients in wound healing. Particularly, a type of exercise intervention known as whole-body vibration (WBV) exercise has gained increasing interest. WBV exercise is generated due to the transmission of mechanical vibrations, produced by a vibrating platform, to the body. The aim of this review was to summarize studies in experimental animal models using WBV exercise in wound healing. Searches were performed in EMBASE, PubMed, Scopus and Web of Science including publications on 21 November 2022 using the string "whole body vibration" AND "wound healing" (animal or mice or mouse or rat or rodent). The SYRCLE tool was used to assess the risk of bias (RoB). From 48 studies, five studies met the inclusion criteria. RoB indicated that none of the studies fulfilled all methodological analyzed criteria, resulting in possible biases. The studies were homogeneous, and results suggest beneficial effects of WBV exercise in wound healing, mainly related to enhancing angiogenesis, granulation tissue formation, reducing the blood glucose level and enhancing blood microcirculation, by increasing myofiber growth and rapid re-epithelialization. In conclusion, the various biological effects of the response to the WBV exercise indicate the relevance of this intervention in wound healing in animals. Moreover, considering the translation approach, it is possible to speculate that the beneficial effects of this non-pharmacological therapy might justify clinical trials for wound healing also in humans, after criterion evaluation.

Effect of Localized Vibration Massage on Popliteal Blood Flow

There is a broad scope of literature investigating whole-body vibration (WBV) effects on blood flow (BF). However, it is unclear how therapeutic localized vibrations alter BF. Low-frequency massage guns are advertised to enhance muscle recovery, which may be through BF changes; however, studies using these devices are lacking. Thus, the purpose of this study was to determine if popliteal artery BF increases from localized vibration to the calf. Twenty-six healthy, recreationally active university students (fourteen males, twelve females, mean age 22.3 years) participated. Each subject received eight therapeutic conditions randomized on different days with ultrasound blood flow measurements. The eight conditions combined either control, 30 Hz, 38 Hz, or 47 Hz for a duration of 5 or 10 min. BF measurements of mean blood velocity, arterial diameter, volume flow, and heart rate were measured. Using a cell means mixed model, we found that both control conditions resulted in decreased BF and that both 38 Hz and 47 Hz resulted in significant increases in volume flow and mean blood velocity, which remained elevated longer than the BF induced by 30 Hz. This study demonstrates localized vibrations at 38 Hz and 47 Hz significantly increase BF without affecting the heart rate and may support muscle recovery.

The Effect of Vibration on the Acceleration of Wound Healing of Diabetic Neuropathic Foot Ulcer: A Prospective Experimental Study on Human Patients

Diabetic foot ulcers are a common complication that occurs in approximately 15 percent of patients with diabetes mellitus. Over 60% of diabetic foot ulcers are caused by underlying neuropathy. Former studies on diabetic animals with foot wounds found that vibration platforms significantly accelerate wound healing by catalyzing epithelization, promoting angiogenesis, and enhancing muscle bulk. This result suggests that there is evidence that vibrations may accelerate diabetic neuropathic ulcer healing in human patients. However, to the best of our knowledge, the effect of vibration on the enhancements of diabetic foot ulcer healing in human patients is rarely investigated. Hence, in this work, we conducted an experimental study with human subjects to investigate whether vibration therapy, as a complement to the standard wound treatment, can accelerate the wound healing rate of diabetic neuropathic foot ulcers. In this prospective experimental study, 80 participants diagnosed with Wagner grades I−III diabetic neuropathic foot ulcers were randomly distributed to experimental (n = 40) and control groups (n = 40). Patients in the intervention group received standard wound treatment and vibration wound therapy (VWT), whereas patients in the control group retrieved only standard wound treatment. The results (p = 0.024, α = 0.05) show notable differences in the median healing rate between the intervention group (25 days, 95% CI: 20.3−29.7) and control group (33 days, 95% CI: 25.6−40.4), with the effect-size r, Cohen’s d, Glass’s Δ, and Hedges’ g, respectively, being 0.810, 2.764, 2.311, and 2.772. Moreover, the nitric oxide (NO) level, wound closure area, and wound healing score after intervention significantly differed between the two groups (p < 0.05), putting the intervention group on a higher level than the control group. Furthermore, positive associations were found between the NO level and wound healing closure rates. These findings suggested that VWT enhances diabetic neuropathic foot ulcer healing in terms of healing rate, wound closure area, healing score, and elevated NO level. Considering that no clinically adverse effects were found in the patients induced with vibration intervention, VWT can be regarded as a complementary therapy to the existing ones to accelerate the healing of DFUs.

Optimization of photo-biomodulation therapy for wound healing of diabetic foot ulcers in vitro and in vivo

Unclear optical parameters make photo-biomodulation (PBM) difficult to implement in diabetic foot ulcer (DFU) clinically. Here, 12 wavelengths (400-900 nm) were used to conduct PBM to heal DFU wounds in vitro and in vivo. PBM at 10 mW/cm² and 0.5-4 J/cm² with all 12 wavelengths promoted proliferation of diabetic wound cells. In a mimic DFU (mDFU) rat model, PBM (425, 630, 730, and 850 nm, and a combination light strategy) promoted mDFU healing. The positive cell proliferation, re-epithelialization, angiogenesis, collagen synthesis, and inflammation were possible mechanisms. The combination strategy had the best effect, which can be applied clinically.

When Two Is Better Than One: A Pilot Study on Transcranial Magnetic Stimulation Plus Muscle Vibration in Treating Chronic Pelvic Pain in Women

Chronic pelvic pain syndrome (CPPS) affects about 4–16% of adult women, and about one-third of them require medical assistance due to severe symptoms. Repetitive transcranial magnetic stimulation (rTMS) over the supplementary motor area (SMA) has been shown to manage pain in refractory CPPS. Focal muscle vibration (FMV) has also been reported to relieve pelvic pain. The objective of this study was to assess the feasibility and effect of rTMS coupled with FMV to reduce pain in seven adult women with refractory CPPS. This pilot, open-labeled, prospective trial examined treatment by 5 Hz rTMS over SMA and 150 Hz FMV over the perineum, suprapubic, and sacrococcygeal areas, with one daily session for five consecutive days for three weeks. We assessed tolerance and subjective pain changes (as per visual analog scale, VAS) until one month post-treatment, with a primary endpoint at day 7. No patients experienced serious adverse effects or a significant increase in pain. Six out of seven patients experienced a VAS improvement of at least 10% at T7; three of these individuals experienced a VAS improvement of more than 30%. Overall, we found a significant VAS reduction of 15 points (95% CI 8.4–21.6) at T7 (t = 6.3, p = 0.001; ES = 2.3 (1.1–3.9)). Three of the women who demonstrated a significant VAS reduction at T7 retained such VAS improvement at T30. VAS decreased by six points (95% CI 1.3–10.7) at T30 (t = 3.1, p = 0.02; ES = 1.5 (0.2–2.6)). This coupled approach seems promising for pain management in adult women with refractory CPPS and paves the way for future randomized controlled trials.

Protective effects of low-magnitude high-frequency vibration on high glucose-induced osteoblast dysfunction and bone loss in diabetic rats

Objective

Low-magnitude high-frequency vibration (LMHFV) has been reported to be capable of promoting osteoblast proliferation and differentiation. Reduced osteoblast activity and impaired bone formation were related to diabetic bone loss. We investigated the potential protective effects of LMHFV on high-glucose (HG)-induced osteoblasts in this study. In addition, the assessment of LMHFV treatment for bone loss attributed to diabetes was also performed in vivo.

Method

MC3T3-E1 cells induced by HG only or treated with LMHFV were treated in vitro. The experiments performed in this study included the detection of cell proliferation, migration and differentiation, as well as protein expression. Diabetic bone loss induced by streptozotocin (STZ) in rats was established. Combined with bone morphometric, microstructure, biomechanical properties and matrix composition tests, the potential of LMHFV in treating diabetes bone loss was explored.

Results

After the application of LMHFV, the inhibiting effects of HG on the proliferation, migration and differentiation of osteoblasts were alleviated. The GSK3β/β-catenin pathway was involved in the protective effect of LMHFV. Impaired microstructure and biomechanical properties attributed to diabetes were ameliorated by LMHFV treatment. The improvement of femur biomechanical properties might be associated with the alteration of the matrix composition by the LMHFV.

Conclusion

LMHFV exhibited a protective effect on osteoblasts against HG by regulating the proliferation, migration and differentiation of osteoblasts. The function of promoting bone formation and reinforcing bone strength made it possible for LMHFV to alleviate diabetic bone loss.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13018-021-02803-w.

The effects of whole-body vibration on wound healing in a mouse pressure ulcer model

BACKGROUND

Pressure ulcers are one of the most common complications of immobility resulting from pressure and shear. Whole-body vibration (WBV) has been shown to increase skin blood flow but little information is known about its effect on pressure ulcers. This study investigated the effects of WBV on wound healing in a mouse pressure ulcer model.

METHODS

Two cycles of ischemia-reperfusion were performed by external application of two magnetic plates to dorsal skin to induce stage II pressure ulcers characterized by partial-thickness skin loss with exposed dermis. A total of 32 male ICR mice were randomly and equally divided into untreated control and the WBV groups. Immediately after the completion of 2-cycle ischemia-reperfusion injury, mice in the WBV group participated in a WBV program using a vibrator (frequency 45 Hz, peak acceleration 0.4 g, vertical motion) for 30 min/day and 5 consecutive days/week. At days 7 and 14 post-ulceration, wound closure rate was assessed. Wound tissues were harvested for determination of collagen deposition in Masson's trichrome stained sections, neutrophil infiltration and capillary density in hematoxylin and eosin-stained sections, as well as TNF-α and VEGF levels using ELISA.

RESULTS

TNF-α levels and neutrophil infiltration were significantly decreased in wounds on days 7 and 14 of WBV treatment. Moreover, wound closure rate and collagen deposition were remarkably accelerated on day 14. Tissue VEGF and capillary density were unaffected by WBV at either time point.

CONCLUSIONS

These findings suggest that WBV has the potential to promote the healing process of stage II pressure ulcers, as evidenced by attenuation of wound inflammation and enhancement collagen deposition.

Wearable Focal Muscle Vibration on Pain, Balance, Mobility, and Sensation in Individuals with Diabetic Peripheral Neuropathy: A Pilot Study

People with diabetic peripheral neuropathy (DPN) experience a lower quality of life caused by associated pain, loss of sensation and mobility impairment. Current standard care for DPN is limited and lacking. This study explores the benefits of 4-week, in-home wearable focal muscle vibration (FMV) therapy on pain, balance, mobility, and sensation in people with DPN. Participants were randomized into three groups and received different FMV intensities. FMV was applied using a modified Myovolt^TM wearable device to the tibialis anterior, distal quadriceps, and gastrocnemius/soleus muscles on both lower limbs for three days a week over four weeks. The outcomes included pain, balance, mobility, sensation, device usage log, feedback survey, and a semi-structured interview. In all, 23 participants completed the study. The results showed significant improvement in average pain (Pre: 4.00 ± 2.29; Post: 3.18 ± 2.26; p = 0.007), pain interference with walking ability (Pre: 4.14 ± 3.20; Post: 3.09 ± 1.976; p = 0.03), and standard and cognitive Timed Up-and-Go scores (Pre: 13.75 ± 5.34; Post: 12.65 ± 5.25; p = 0.04; Pre: 15.12 ± 6.60; Post: 12.71 ± 5.57; p = 0.003, respectively); the overall pain improvement was trending towards significance (Pre: 3.48 ± 2.56; Post: 2.87 ± 1.85; p = 0.051). Balance and sensations improved but not significantly. There was a trend towards significance (p = 0.088), correlation (r = 0.382) between changes in balance and baseline pain. The participants were highly satisfied with wearable FMV and were 100% compliant. FMV therapy was associated with improved pain, mobility, and sensation. Further study with a larger sample and better outcome measures are warranted.

Vibrational stress affects extracellular signal-regulated kinases activation and cytoskeleton structure in human keratinocytes

As the outermost organ, the skin can be damaged following injuries such as wounds and bacterial or viral infections, and such damage should be rapidly restored to defend the body against physical, chemical, and microbial assaults. However, the wound healing process can be delayed or prolonged by health conditions, including diabetes mellitus, venous stasis disease, ischemia, and even stress. In this study, we developed a vibrational cell culture model and investigated the effects of mechanical vibrations on human keratinocytes. The HaCaT cells were exposed to vibrations at a frequency of 45 Hz with accelerations of 0.8g for 2 h per day. The applied mechanical vibration did not affect cell viability or cell proliferation. Cell migratory activity did increase following exposure to vibration, but the change was not statistically significant. The results of immunostaining (F-actin), western blot (ERK1/2), and RT-qPCR (FGF-2, PDGF-B, HB-EGF, TGF-β1, EGFR, and KGFR) analyses demonstrated that the applied vibration resulted in rearrangement of the cytoskeleton, leading to activation of ERK1/2, one of the MAPK signaling pathways, and upregulation of the gene expression levels of HB-EGF and EGFR. The results suggest that mechanical vibration may have wound healing potential and could be used as a mechanical energy-based treatment for enhancing wound healing efficiency.

Vibration and β-hydroxy-β-methylbutyrate treatment suppresses intramuscular fat infiltration and adipogenic differentiation in sarcopenic mice

BACKGROUND

Sarcopenia is an aging-induced deterioration of skeletal muscle mass and function. Low-magnitude high-frequency vibration (LMHFV) was shown to improve muscle functions and β-hydroxy-β-methylbutyrate (HMB) to increase muscle mass and strength. Muscle-derived stem cells (MDSCs) are progenitor cells important for muscle regeneration. We hypothesized that LMHFV and HMB could retard sarcopenia by reducing fat infiltration through inhibiting adipogenesis in MDSCs.

METHODS

Senescence-accelerated mouse P8 male mice were randomized into control (CTL), HMB, LMHFV (VIB), and combined (COM) groups. Interventions started at age of month 7 and assessed at 1, 2, and 3 months post-intervention by densitometry, histology, and functional tests. In vitro, MDSCs isolated from gastrocnemius of senescence-accelerated mouse P8 mice were characterized, randomized into CTL, VIB, HMB, and COM groups, and assessed by oil red O staining, mRNA, and protein expression.

RESULTS

At 2 months post-intervention, percentage lean mass of HMB, VIB, and COM groups were significantly higher than CTL group. Twitch, tetanic, and specific tetanic forces of COM group were higher, while specific twitch force of both VIB and COM groups were higher. Grip strength of HMB, VIB, and COM groups were higher. Histologically, both VIB and COM groups presented lower oil red O area than CTL group. Type I muscle fibre in CTL group was higher than HMB, VIB, and COM groups. MDSC were detected in situ by immunofluorescence stain with stem cell antigen-1 signals confirmed with higher β-catenin expression in the COM group. The observations were also confirmed in vitro, MDSCs in the HMB, VIB, and COM groups presented lower adipogenesis vs. the CTL group. β-Catenin mRNA and protein expressions were lower in the CTL group while their relationship was further validated through β-catenin knock-down approach.

CONCLUSIONS

Our results showed that combined LMHFV and HMB interventions enhanced muscle strength and decreased percentage fat mass and intramuscular fat infiltration as compared with either treatment alone. Additive effect of LMHFV and HMB was demonstrated in β-catenin expression than either treatment in MDSCs and altered cell fate from adipogenesis to myogenesis, leading to inhibition of intramuscular lipid accumulation. Wnt/β-catenin signalling pathway was found to be the predominant regulatory mechanism through which LMHFV and HMB combined treatment suppressed MDSCs adipogenesis.

Effects of Local Vibration With Different Intermittent Durations on Skin Blood Flow Responses in Diabetic People

Objective: Poor blood flow supply is an important pathological factor that leads to the development and deterioration of diabetic foot ulcers. This study aims to investigate the acute effects of local vibration with varying intermittent durations on the plantar skin blood flow (SBF) response in diabetic and healthy subjects.

Methods: Eleven diabetic patients (7 males, 4 females) and 15 healthy adults (6 males, 9 females) participated in this experiment and accepted three tests. Local continuous vibration (LCV) and two levels of local intermittent vibration (LIV1 and LIV2) were randomly applied to the middle metatarsal head of each subject's right foot in each test. The SBF was measured prior to intervention (Baseline), during Vibration and during the Recovery Stage for each test. The mean SBF in each stage, the change percentages and change rates of SBF in Vibration and Recovery stage among three tests were compared and analyzed for both diabetic and healthy subjects.

Results: For diabetic subjects, the SBF was significantly increased in both Vibration and Recovery Stage with local intermittent vibrations (LIV1 and LIV2), but not with LCV. However, there was no significant difference in change percentage and change rate of SBF in diabetic subjects across the three tests. For healthy subjects, all vibration interventions significantly increased the SBF in the Vibration Stage and in the first 1.5 min of the Recovery Stage. Also, the change rate of SBF during the Vibration stage in LIV1 test was significantly greater than that in LIV2 test for healthy subjects. Moreover, change percentage of SBF in Vibration stage of LIV1 test and in some periods of Recovery stages of LIV1 and LIV2 tests for diabetic subjects were lower than for healthy subjects; the absolute change rate of SBF in LIV1 test for diabetic subjects was also lower than for healthy subjects.

Conclusion: These findings suggest that both LIV1 and LIV2 may effectively improve SBF in the feet of diabetic people, but LCV may not achieve the same level of vasodilatation. The diabetic subjects were also found to have a lower SBF response to applied vibration than the healthy subjects.