The Effects of Botulinum Toxin A on Survival of Rat TRAM Flap With Vertical Midline Scar

Botulinum Toxin to Improve the Prognosis of Skin Transplantation: A Short Narrative Review

Skin transplantation is a traditional and well-established method of repairing skin loss, especially deep second-degree postburn wounds. Complications often happen amid the healing process, including necrosis and skin contracture, which has raised widespread concern from patients and doctors. Since the first recorded medical application of botulinum toxin for strabismus, accumulating evidence has enclosed all-round potential of botulinum toxin, more than aesthetic management. In recent decades, botulinum toxin also has been revealed to improve the prognosis of skin grafts. This literature review aims to briefly summarize the history and latest advances of its use for skin transplantation.

Botulinum Toxin A and B Improve Perfusion, Increase Flap Survival, Cause Vasodilation, and Prevent Thrombosis: A Systematic Review and Meta-analysis of Controlled Animal Studies

BACKGROUND

A systematic review and meta-analysis of case-control animal model studies will help clarify the vascular effects of botulinum toxin (BTX).

METHODS

Preferred Reporting Items of Systematic reviews and Meta-Analyses guidelines were used to identify all animal case-control studies published before September 13, 2020, evaluating the vascular effects of BTX. Primary parameters included the following: perfusion, flap survival, arterial and venous dilation, and arterial and venous thrombosis.

RESULTS

Thirty-six studies with 1032 animals met the systematic review inclusion criteria. Twenty-nine studies had quantifiable data for statistical analysis. Statistically significant increases in perfusion with BTX over saline were detected within 1 day and sustained up to 8 weeks. The following represent weighted mean data from the meta-analysis. The administration of BTX has a 26% increase in both random pattern and pedicled flap survival area over controls. Botulinum toxin causes vasodilation. Botulinum toxin increases vessel diameter in arteries by 40% and in veins by 46% compared with saline controls. The administration of BTX reduces thrombosis by 85% in arteries and by 79% in veins compared with saline controls. Vascular effects were consistent across both BTX-A and BTX-B serotypes, multiple animal species, and various doses. No clear relationships between vascular effects and BTX pretreatment time were identified.

CONCLUSIONS

Perivascular BTX administration intraoperatively or as a chemical delay pretreatment several days before surgery in multiple animal species and models shows multiple changes to the vascular system. Extrapolation of lessons learned from this systematic review and meta-analysis of animal models could expand research and clinical use of BTX in human vascular disease and surgery.

Botulinum Toxin Type A for the Treatment of Skin Ulcers: A Review Article

The normal biological wound healing process consists of three precisely and highly programmed phases that require optimal conditions including internal and external factors. Any negative factors that disrupt the sequence or time frame of the healing mechanism can result in a non-healing wound or chronic ulcers. Botulinum neurotoxin A (BoNT-A) which is generally known as anti-contraction of muscles has been reported as a successful treatment in various types of chronic ulcers. The aim of this study is to review the outcome of treatment with BoNT-A for chronic skin ulcers. The results demonstrated some positive effects of BoNT-A on chronic ulcers. Ischemic ulcers secondary to Raynaud’s phenomenon seem to be the most promising type of ulcers that have benefited from BoNT-A. The rationale behind using BoNT-A to fasten the wound healing process is also discussed. Further clinical trial studies should be conducted to affirm the efficacy of wound healing using BoNT-A administration.

Effect of botulinum toxin type A on flap surgery in animal models: a systematic review and meta-analysis

Flaps are common technical choices in aesthetic and reconstructive surgeries. However, the poor flap survival rate remains to be a difficult issue that troubles plastic surgeon. Recent research evidence supports that the use of Botulinum toxin type A (BTXA) can increase the flap survival rate. For verification, the present study was carried out to evaluate the effect of BTXA on flap surgery. Eight databases (PubMed, Cochrane Library, Ovid, Web of Science, Embase, Scopus, CBM, CNKI and WANFANG database) were searched for related published literature up to September 2020. A meta-analysis was then conducted to compare the effect of using BTXA with that of using saline or no treatment in flap surgery. Seventeen studies with a total of 565 animals were finally included in this review after strict exclusion and inclusion. Compared with saline/no treatment + flap group, BTXA + flap group showed a significantly higher flap tissue survival rate (mean difference [MD] 15.55, p < 0.00001), blood flow (standardized mean difference [SMD] 1.97, p < 0.00001) and vascular endothelial growth factor (VEGF) expression (at mRNA level: SMD 6.01, p = 0.02; at protein level: SMD 3.35, p < 0.00001). BTXA combined with flap surgery may have a positive effect on improving the flap tissue survival rate, blood flow of flaps and VEGF expression. Besides, the timing of BTXA injection may be an important factor for exerting its effect on flap surgery.

The Effect of Botulinum Toxin on Flap Viability of the Posterior Thigh Perforator Flap in Rats

BACKGROUND

The use of perforator propeller flaps in lower limb reconstruction has increased recently. Many pharmacological agents are used to increase flap viability. Botulinum toxin has been used in various types of flaps in the literature. However, there is no study regarding the use of botulinum toxin in the lower limb propeller flaps. This study investigates the effect of botulinum toxin administration on flap survival for lower limb propeller flap in rats.

MATERIALS AND METHODS

The study included 20 male Wistar albino rats, divided into two groups with a flap rotation of 90° in group 1 and 180° in group 2. In both groups, botulinum toxin was administered to the right thigh and a physiological saline solution was applied to the left thigh. Five days later, flaps were elevated over the posterior aspect of the right and left thighs and inset after 90° and 180° rotation was performed. Histopathological, immunohistochemical, and necrosis area analyses were performed.

RESULTS

Necrosis area, edema, polymorphonuclear leukocyte infiltration, and necrosis were found to be higher on the left side of the groups, whereas epidermal thickness, collagen density, vascularization, and hair root density were found to be higher on the right side of the groups. No significant difference was found between the right posterior thighs in either group on any parameter other than vascularization. Histopathologically and immunochemically statistically significant differences were found between the two groups.

CONCLUSIONS

The present study found that botulinum toxin increases flap viability in lower limb perforator-based propeller flaps.

Viability of transverse rectus abdominis musculocutaneous flap treated with photobiomodulation and therapeutic ultrasound: an experimental model

Report the effects of photobiomodulation (PBM) and therapeutic ultrasound (TUS) on the viability of TRAM in mice.

MATERIALS AND METHODS

Fifty-five mice Swiss were subjected to treatment for 5 days. Group 1, treatment was performed with the agents switched off. Groups 2 to 5 were treated with different wavelengths 660 and 830 nanometers (nm) and groups 6 to 11 with TUS of 1 and 3 MHz frequency. Macrometric analyses were performed using a specific camera and analyzed by the ImageJ® software. Thermographic analyses were performed with the Flir C2 and analyzed using the FLIR Tools software.

RESULTS

Group 9 obtained 95% of viable area on the 3rd day and 85% on the 5th day, showing the effectiveness of the TUS in the flap viability. Regarding skin temperature, there was a difference only in the immediate postoperative period in group 1, which had a lower temperature than the other groups.

CONCLUSIONS

TUS demonstrated greater efficiency in maintaining the viability of TRAM. PBM 830 nm also demonstrated good results in the viability of TRAM.

Botulinum Toxin Type A Attenuates Apoptosis in Human Dermal Microvascular Endothelial Cells Exposed to an In Vitro Model of Ischemia/Reperfusion Injury

BACKGROUND

Botulinum toxin type A (BTXA) has been reported to increase survival of critically ischemic skin flaps; however, the effect of BTXA in human dermal microvascular endothelial cells (HDMECs) remains to be investigated. This study aimed to investigate the protective effect of BTXA in HDMECs exposed to an in vitro model of ischemia/reperfusion injury.

METHODS

HDMECs were isolated from human upper eyelid tissue and were randomly divided into 3 groups: 1.

CONTROL GROUP

culture under normoxic conditions (95% air and 5% CO₂); 2. hypoxia/reoxygenation (H/R) group: culture in a hypoxic incubator (94% N₂ + 5% CO₂ + 5% O₂) for 8 hours, followed by culture in saturated aerobic culture medium for 24 hours; and 3. BTXA group: treatment with BTXA for 12 hours before exposure to hypoxic conditions. Flow cytometry was used to analyze the apoptosis of HDMECs, and western blotting was used to detect the expression of apoptosis-related proteins.

RESULTS

H/R leads to severe injury in HDMECs, as evidenced by an increase in the percentage of apoptosis and an increase in expression of apoptosis-related proteins (Bax, cleaved-caspase-3, and cytochrome C). Moreover, H/R results in a decrease in expression of anti-apoptotic protein (Bcl-2), which can be significantly attenuated with BTXA treatment.

CONCLUSION

BTXA protects against apoptosis in HDMECs exposed to an in vitro model of H/R-induced injury.

Effect of Perivascular Injection of Botulinum Toxin Type A versus Lidocaine in Survival of Random Pattern Flaps in a Rat Model

BACKGROUND

Botulinum toxin type A has gained popularity in many clinical fields, for a variety of aesthetic and therapeutic purposes. In addition, there have been reports regarding the positive effect of botulinum toxin type A on flap survival by various mechanisms. This study examines the role of botulinum toxin type A and lidocaine in augmentation of flap survival and decreasing the rate of necrosis in random pattern cutaneous flaps.

METHODS

In 45 male Sprague-Dawley rats, random pattern skin flaps with different width-to-length ratios were elevated. Botulinum toxin type A, lidocaine, or saline was administered to the base and whole length of the flap. Flap survival was evaluated on day 10 after surgery. The area of flap survival was determined grossly on the basis of its appearance, color, and texture.

RESULTS

The botulinum toxin type A group had a greater survival area (p < 0.05) compared with the lidocaine or saline group in flaps with width-to-length ratios of 1:2 and 1:3; however, compared with a width-to-length ratio of 1:1, the flap survival rate shows no statistically significant variations.

CONCLUSION

Injection of botulinum toxin type A in random pattern skin flaps improves tissue perfusion and increases the rate of flap survival more than lidocaine in flaps with width-to-length ratios of 1:2 and 1:3.

The Use of Botulinum Toxin in Flap Surgery: A Review of the Literature

Botulinum neurotoxin-A and botulinum neurotoxin-B have been shown to play a potential role in improving flap survival in animal models. The aim of this study is to review indications as well as to study injection timing, technique, and doses of botulinum neurotoxin-A and botulinum neurotoxin-B in animal models. Seventeen articles describe a total of 266 animals that underwent botulinum toxin injections before or during flap harvesting or vascular anastomosis procedure. All the studies demonstrated a beneficial effect of botulinum toxin administration in flap surgery or vascular anastomosis. Botulinum neurotoxin-A injection was shown to be a reliable approach in reducing vascular complications rate and increasing survival of flaps in animal models. The main conclusions drawn from the study include the following: perivascular injections targeting each vascular pedicle are preferred in cases of free flaps or axial flaps; subdermal injections are favorable in cases of random pattern skin flaps; and injections should be performed 7 days before flap elevation.

Role of botulinum neurotoxin-A in cerebral revascularization graft vasospasm prevention: current state of knowledge

Graft stenosis and occlusion remain formidable complications in cerebral revascularization procedures, which can lead to significant morbidity and mortality. Graft vasospasm can result in early postoperative graft stenosis and occlusion and is believed to be at least partially mediated through adrenergic pathways. Despite various published treatment protocols, there is no single effective spasmolytic agent. Multiple factors, including anatomical and physiological variability in revascularization conduits, patient age, and comorbidities, have been associated with graft vasospasm pathogenesis and response to spasmolytics. The ideal spasmolytic agent thus likely needs to target multiple pathways to exert a generalizable therapeutic effect. Botulinum toxin (BTX)-A is a powerful neurotoxin widely used in clinical practice for the treatment of a variety of spastic conditions. Although its commonly described paradigm of cholinergic neural transmission blockade has been widely accepted, evidence for other mechanisms of action including inhibition of adrenergic transmission have been described in animal studies. Recently, the first pilot study demonstrating clinical use of BTX-A for cerebral revascularization graft spasm prevention has been reported. In this review, the mechanistic basis and potential future clinical role of BTX-A in graft vasospasm prevention is discussed.

Botulinum toxin B suppresses the pressure ulcer formation in cutaneous ischemia-reperfusion injury mouse model: Possible regulation of oxidative and endoplasmic reticulum stress

BACKGROUND

We previously identified that botulinum toxin A (BTX-A) suppressed pressure ulcer (PU) formation after cutaneous ischemia-reperfusion (I/R) injury; however, regulation of cutaneous I/R-induced oxidative and endoplasmic reticulum (ER) stress by BTX-B was not investigated. Additionally, the efficacy of BTX-B injection has never been examined.

OBJECTIVE

Objective was to assess the effects of BTX-B on the formation of PU by cutaneous I/R injury, and the regulation of oxidative and ER stress in I/R injury by BTX-B.

METHODS

BTX-B was subcutaneously injected into I/R area, and wound size, vascular damage, hypoxic area, and apoptotic cells in I/R area were analyzed. We evaluated the extent of oxidative and ER stress in I/R area by using OKD48 mice and ERAI mice, respectively, which enabled evaluating oxidative and ER stress through bioluminescence detection.

RESULTS

BTX-B injection significantly suppressed the formation of PU by cutaneous I/R injury. Cutaneous I/R-induced vascular damage, hypoxic area, and number of oxidative-damaged cells and apoptotic cells were suppressed by BTX-B injection. BTX-B administration significantly inhibited I/R-induced oxidative stress signal in OKD48 mice. BTX-B reduced the I/R-induced oxidative stress-associated factors. BTX-B significantly inhibited the oxidant-induced reactive oxygen species and apoptosis of endothelial cells and fibroblasts. BTX-B significantly inhibited I/R-induced ER stress signal in ERAI mice. Cutaneous I/R injury-induced ER stress-response factors and GRP78/BiP and CHOP-positive cells in I/R area were significantly decreased by BTX-B injection.

CONCLUSION

BTX-B injection might have protective effects against PU formation after cutaneous I/R injury by reducing vascular damage, hypoxia-induced oxidative and ER stress, and apoptosis.

Botulinum toxin A increases allograft tolerance in an experimental transplantation model: a preliminary study

Identifying novel and safe immunosuppressants is of crucial importance. Recently, there have been several studies revealing that botulinum toxin A (BoTA) significantly alleviates ischemia–reperfusion injuries. Emerging evidence shows that ischemia–reperfusion injuries contribute to innate immune activation, promoting rejection, and inhibiting tolerance. Therefore, we hypothesized that a pretreatment with BoTA might decrease allograft rejection in a rat transplantation model. Twenty-four Lewis (LEW) rats were randomly assigned into two groups consisting of 12 rats each, depending on whether skin allograft was performed after pretreatment with BoTA (BoTA group) or with normal saline (control group). The experimental group was pretreated with a subcutaneous injection of BoTA (10 IU), while the control group was pretreated with normal saline 5 days prior to surgery. The donor Brown–Norway (BN) rat dorsal skin was subsequently grafted to the recipient LEW rats. The recipient wounds, measuring 2 cm × 2 cm, were made via dorsal skin excision through the panniculus carnosus. The donor skins of the same dimensions were obtained and transplanted on to the wounds and sutured with 4-0 nylon sutures. Mean graft survival time was measured in both groups. Quantitative reverse-transcriptase PCR and Western blotting were performed to evaluate the gene/protein expression of CD4 and VEGF. The mean graft survival time in the BoTA group was significantly longer than that of the control group (P=0.004). The relative mRNA and protein expression of CD4 was significantly lower in the BoTA group (P<0.001), while the relative mRNA and protein expression of VEGF was significantly higher in the BoTA group (P<0.001). In conclusion, our results show that BoTA prolongs the survival of skin allografts in a rat transplantation model.

The Effect of Botulinum Toxin A on Ischemia-Reperfusion Injury in a Rat Model

Introduction

While studies using various materials to overcome ischemia-reperfusion (IR) injury are becoming increasingly common, studies on the effects of botulinum toxin A (BoTA) on IR injury in musculocutaneous flaps are still limited. The purpose of this study was to examine our hypotheses that BoTA provide protection of musculocutaneous flap from ischemia-reperfusion injury.

Method

Five days after pretreatment injection (BoTA versus normal saline), a right superior musculocutaneous flap (6 × 1.5 cm in size) was made. Ischemia was created by a tourniquet strictly wrapping the pedicle containing skin and muscle for 8 h. After ischemia, the tourniquet was cut, and the musculocutaneous flap was reperfused.

Results

The overall survival percentage of flap after 8 h of pedicle clamping followed by reperfusion was 87.32 ± 3.67% in the control group versus 95.64 ± 3.25% in the BoTA group (p < 0.001). The BoTA group had higher expression of CD34, HIF-1α, VEGF, and NF-kB comparing to control group in qRT-PCR analysis.

Conclusions

In this study, we found that local BoTA preconditioning yielded significant protection against IR injury in a rat musculocutaneous flap model.

Botulinum Toxin A Upregulates Rac1, Cdc42, and RhoA Gene Expression in a Dose-Dependent Manner: In Vivo and in Vitro Study

Angiogenesis is the development of new capillaries from existing blood vessels and is a prerequisite for the wound-healing process. Many lines of scientific evidences have shown that complicated roles of small guanosine triphosphatases (GTPases) (ras-related C3 botulinum toxin substrate 1 [Rac1], cell division control protein 42 [Cdc42], and ras homolog gene family, member A [RhoA]) in regulation of signal transduction pathways exist to transmit distinct cellular effects on the modulation of actin cytoskeleton remodeling such as cell cycle progression, cell survival, and cell motility. In addition, these small GTPases activate mitogen-activated protein kinase kinase kinases (MAP3Ks) leading to activated mitogen-activated protein kinase kinases (MAPKK), mitogen-activated protein kinase (MAPK), and various transcription factors such as vascular endothelial growth factor with involvement of MAPK signaling pathways.In this study, the authors hypothesized that botulinum toxin A increases angiogenesis via the expression of small GTPases in vivo and in vitro studies.In vivo experiment, 24 Sprague-Dawley rats were randomly divided into 2 groups: a control group and a botulinum toxin A group. Five days prior to superiorly based transverse rectus abdominis myocutaneous flap elevation, the botulinum toxin A (BoTA) group was pretreated with BoTA, while the control group was pretreated with normal saline. quantitative real-time polymerase chain reaction was performed to evaluate the expression of Rac1, RhoA, and Cdc42.The angiogenic effects of botulinum toxin A on human dermal fibroblasts were measured in vitro experiment. To understand the mechanism of botulinum toxin A on small GTPases production of fibroblasts, Rac1, Cdc42, and RhoA were measured using qRT-PCR.The relative messenger ribonucleic acid expression of Rac1, RhoA, and Cdc42 was significantly higher in the BoTA group than in the control group, in every zone and pedicle muscle, on postoperative days 1, 3, and 5. Levels of these molecules increased significantly in human dermal fibroblasts grown in the presence of BoTA compared with control group over 5 IU.Our in vivo and in vitro studies suggest that administration of BoTA upregulates the expression of RhoA, Rac1, and Cdc42 in a dose-dependent manner. MAPK signaling pathway might be involved in BoTA-induced angiogenesis mechanism.

LEVEL OF EVIDENCE

N/A.

A case report of the beneficial effects of botulinum toxin type A on Raynaud phenomenon in a patient with lung cancer

OBJECTIVE

Raynaud phenomenon is a vasospastic disorder affecting the hands and feet, and the efficacies of traditional treatments, such as pharmacological therapies and sympathectomy, are not uniform. Patients with paraneoplastic Raynaud phenomenon do not benefit from the traditional treatments. The use of botulinum toxin type A (BTX-A) for Raynaud phenomenon has been reported for several years; however, there are few reports regarding botulinum toxin type A in the treatment of paraneoplastic Raynaud phenomenon. We describe a case report of the beneficial effects of botulinum toxin type A on Raynaud phenomenon in a patient with lung cancer.

METHODS

A 63-year-old male complained of pain and discoloration of his fingers and indicated that oral nifedipine and low-dose aspirin were not effective. After approximately 8 months, he was diagnosed with lung cancer. Chemotherapy partially reduced the pain and discoloration of his fingers; however, no significant changes occurred in his fingers after the fourth cycle. We used BTX-A to treat this patient with paraneoplastic RP. A visual analogue scale (VAS) was used to assess the clinical response.

RESULTS

After approximately 2 months, the patient reported relief from pain, stiffness, numbness, and cold sensation. Furthermore, no local or general adverse effects were exhibited by the patient.

CONCLUSION

This study used botulinum toxin type A for a patient with paraneoplastic Raynaud phenomenon. Botulinum toxin type A significantly improved the patient's clinical symptoms without significant complications. These findings suggest that BTX-A may represent a good option for the treatment of paraneoplastic RP.

Botulinum Toxin Type A and the Prevention of Hypertrophic Scars on the Maxillofacial Area and Neck: A Meta-Analysis of Randomized Controlled Trials

Background

The purpose of the meta-analysis was to evaluate the efficiency of therapeutic botulinum toxin type A (BTX-A) in the prevention of maxillofacial and neck scars.

Methods and Findings

Information came from the following electronic databases: Medline, PubMed, Cochrane Library, and EMBASE (time was ended by August 31, 2015) to retrieve RCTs evaluating the effect of the BTX-A for hypertrophic scar on the maxillofacial or neck. All languages were included as long as they met the inclusion criteria. Here the effects of BTX-A were evaluated by comparing the width of the scar, patient satisfaction, and the visual analysis scores (VAS), respectively. Pooled weighted mean differences (WMDs), pooled odds ratios (ORs), and 95% confidence intervals (CI) were calculated. Nine RCTs covering a total of 539 patients were included. A statistically significant difference in scar width was identified between the BTX-A group and control group (non-BTX-A used) (WMD = -0.41, 95% CI = -0.68 to -0.14, P = 0.003). A statistically significant difference in patient satisfaction was observed between the BTX-A group and control group (OR = 25.76, 95% CI = 2.58 to 256.67, P = 0.006). And in patients regarding visual analysis scores (VAS), a statistically significant difference was also observed between the BTX-A group and control group (WMD = 1.30, 95% CI = 1.00 to 1.60, P < 0.00001).

Conclusions

This meta-analysis evaluates the efficacy of the BTX-A and confirms that BTX-A is a suitable potential therapy for the prevention of hypertrophic scars in patients in the maxillofacial and neck areas.

Protective effect of botulinum toxin A after cutaneous ischemia-reperfusion injury

Botulinum toxin A (BTX-A) blocks the release of acetylcholine vesicles into the synaptic space, and has been clinically used for aesthetic indications, neuromuscular disorders and hyperhidrosis. Several studies have demonstrated that BTX-A enhanced the blood flow and improved ischemia in animal models. Our objective was to assess the effects of BTX-A on cutaneous ischemia-reperfusion (I/R) injuries, mimicking decubitus ulcers. The administration of BTX-A in I/R areas significantly inhibited the formation of decubitus-like ulcer in cutaneous I/R injury mouse model. The number of CD31(+) vessels and αSMA(+) pericytes or myofibroblasts in wounds were significantly increased in the I/R mice treated with BTX-A. The hypoxic area and the number of oxidative stress-associated DNA-damaged cells and apoptotic cells in the I/R sites were reduced by BTX-A administration. In an in vitro assay, BTX-A significantly prevented the oxidant-induced intracellular accumulation of reactive oxygen species (ROS) in vascular endothelial cells. Furthermore, the administration of BTX-A completely suppressed the ulcer formation in an intermittent short-time cutaneous I/R injury model. These results suggest that BTX-A might have protective effects against ulcer formation after cutaneous I/R injury by enhancing angiogenesis and inhibiting hypoxia-induced cellular damage. Exogenous application of BTX-A might have therapeutic potential for cutaneous I/R injuries.