Comparison of botulinum toxin type A and aprotinin monotherapy with combination therapy in healing of burn wounds in an animal model

Comparison research on the therapeutic effects of botulinum toxin type A and stromal vascular fraction gel on hypertrophic scars in the rabbit ear model

BACKGROUND AND OBJECTIVES

Botulinum toxin type A (BTA) is often used for wrinkles and muscle convulsive diseases due to its blocking of the transmission of nerve impulses. Stromal vascular fraction gel (SVF-gel) prepared from adipose tissue has novel effects on skin depression and poor texture. Both BTA and SVF-gel are proved to possess anti-scar potential. This study aimed to assess and compare their therapeutic effects on hypertrophic scars.

MATERIALS AND METHODS

The rabbit ear scar model was established and treated with BTA and SVF-gel, alone or in combination. Gross evaluation using Manchester Scar Scale (MSS) was conducted immediately, 4 and 8 weeks after initial treatment. After tissue sample harvest, histological and Western blot analyses were performed.

RESULTS

All the treatments alleviated scar hyperplasia in different degrees by inhibiting fibroblast activation (Ki-67, α-SMA), tissue inflammation (CD45, IL-1β) and the transforming growth factor-β1 (TGF-β1)/Smad3 pathway. Despite an excellent anti-inflammatory effect, improvement of scar appearance and pathological characteristics in SVF-gel-contained groups was not as good as that in BTA-only group, which might be related to the retention of M2-type macrophages (CD163 +) and partial maintenance of TGF-β1 expression.

CONCLUSION

Our data suggest that BTA has better anti-scar efficacy than SVF-gel, and the combination of these two treatments shows no obvious combinatorial effect.

Current Research of Botulinum Toxin Type A in Prevention and Treatment on Pathological Scars

BACKGROUND

Dermatologists have been looking for ways to improve wound healing and postoperative scar appearance. The safety and efficacy of botulinum toxin type A (BTXA) in the prevention and treatment on pathological scars have become the current research hotspot since it was approved by the US FDA in medical cosmetology in 2002.

PURPOSE

This article aims to provide an overview of the clinical research, limitations, and application prospects of BTXA in the prevention and treatment of traumatic or postoperative pathological scars, which can provide a reference and better understanding of relevant studies.

METHODS

The current research progress was summarized and discussed, with new problems and research ideas being proposed ranging from the molecular mechanism of BTXA in preventing and treating pathological scars to its clinical application via investigation and reference research.

RESULTS

BTXA is effective in relieving itching and pain associated with pathological scars, limiting scar hyperplasia along with preventing scar contracture, but the specific mechanism is still not clear.

CONCLUSION

Most of the clinicians have confirmed the clinical effectiveness of BTXA in the prevention and treatment of pathological scars, yet its mode of action and combination therapy need more research.

Pharmaceutical Prophylaxis of Scarring with Emphasis on Burns: A Review of Preclinical and Clinical Studies

Significance: The worldwide estimate of burns requiring medical attention each year is 11 million. Each year in the United States, ∼486,000 burn injuries receive medical attention, including 40,000 hospitalizations. Scars resulting from burns can be disfiguring and impair functions. The development of prophylactic drugs for cutaneous scarring could improve the outcomes for burns, traumatic lacerations (>6 million/year treated in U.S. emergency rooms), and surgical incisions (∼250 million/year worldwide). Antiscar pharmaceuticals have been estimated to have a market of $12 billion. Recent Advances: Many small molecules, cells, proteins/polypeptides, and nucleic acids have mitigated scarring in animal studies and clinical trials, but none have received Food and Drug Administration (FDA) approval yet. Critical Issues: The development of antiscar pharmaceuticals involves the identification of the proper dose, frequency of application, and window of administration postwounding for the indicated wound. Risks of infection and impaired healing must be considered. Scar outcome needs to be evaluated after scars have matured. Future Directions: Once treatments have demonstrated safety and efficacy in rodent and/or rabbit and porcine wound models, human testing can begin, such as on artificially created wounds on healthy subjects and on bilateral-surgical wounds, comparing treatments versus vehicle controls on intrapatient-matched wounds, before testing on separate cohorts of patients. Given the progress made in the past 20 years, FDA-approved drugs for improving scar outcomes may be expected.

The Efficacy and Safety of Botulinum Toxin Injections in Preventing Postoperative Scars and Improving Scar Quality: A Systematic Review and Meta-Analysis

BACKGROUND

Scars exposed on the body surface lead to a large psychological burden on patients. However, no satisfactory scar treatments exist. Botulinum toxin type A is a neurotoxin that has been widely applied in the plastic and cosmetic surgery field. The purpose of this meta-analysis was to assess the efficacy and safety of botulinum toxin in scar management.

METHODS

PubMed, the Cochrane Library, EMBASE, MEDLINE, and Web of Science were searched for randomized controlled trials that evaluated the efficacy of botulinum toxin injections in preventing postoperative scars and improving scars quality and were published prior to Dec. 29, 2020. The outcome indicators were the visual analog scale score, Vancouver scar scale score, Stony Brook scar evaluation scales score, scar width, patient self-assessment results, and complications.

RESULTS

Seventeen randomized controlled trials with a total of 633 cases were identified in this meta-analysis. The quantitative synthesis results showed that compared with the control group, the botulinum toxin group had a significantly lower VSS score (MD = -0.97, 95%CI = -1.56 to -0.39, p = 0.001), higher VAS score (MD = 1.26, 95%CI = 1.04 to 1.47, p < 0.00001), thinner scar width (MD = -0.25, 95%CI = -0.37 to -0.12, p < 0.0001) and higher patient satisfaction (RR = 3.38 95%CI = 1.45 to 7.89, p = 0.005). There were no significant differences between the two groups in the number of adverse events.

CONCLUSIONS

This meta-analysis demonstrated that botulinum toxin injections can significantly improve cosmetic appearance and postoperative scar quality. At the therapeutic dose, no significant complications were observed, indicating that botulinum toxin injections are safe.

LEVEL OF EVIDENCE III

This journal requires that authors assign a level of evidence to each article. For a full description of these evidence-based medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .