Safety and efficacy of botulinum toxin type A in preventing and treating scars in animal models: A systematic review and meta-analysis

Using Neuromodulators to Improve Scar Formation, Keloids, Rosacea, and Antiaging

BACKGROUND

Botulinum toxin A (BoNT-A) treatment has many uses in dermatology. Its mechanism of action and long-term effects for scar formation, rosacea, and antiaging are still being investigated.

OBJECTIVE

To conduct a literature review on BoNT-A to further investigate its use in scar formation, rosacea, and antiaging.

METHODS

A literature review was conducted using PubMed on botulinum toxin treatment for scar formation, rosacea, and antiaging. Studies discussing the toxin mechanism of action and treatment algorithm were included. The authors also provided their personal experience in BoNT-A use for these 3 conditions.

RESULTS

The mechanism of action of Botulinum toxin A in improving scar formation, rosacea, and antiaging is now better understood. While it is effective in the short term, little is still known about how frequently treatment needs to be repeated and if there are any long-term effects.

CONCLUSION

While in vitro studies have supporting evidence on the mechanism of action of BoNT-A on scar formation, rosacea, and antiaging, further studies are needed to identify long-term treatment effects.

Adipose-derived mesenchymal stem cells-sourced exosomal microRNA-7846-3p suppresses proliferation and pro-angiogenic role of keloid fibroblasts by suppressing neuropilin 2

BACKGROUND

Exosomes (Exos) and their contained microRNAs (miRNAs) have been emergingly recognized as key regulators in spanning biological processes, including proliferation and angiogenesis.

AIM OF THE STUDY

This work investigates the function of Exos derived from adipose-derived mesenchymal stem cells (adMSCs) in viability of keloid fibroblasts (KFs).

METHODS

Abnormally expressed miRNAs in keloid tissues were screened using the GEO dataset GSE113620. Meanwhile, miRNAs enriched in adMSC-Exos were predicted by bioinformatics system. Exos were extracted from acquired adMSCs and identified, which were co-incubated with KFs. Uptake of Exos by KFs was examined by fluorescence staining. Viability, proliferation, and apoptosis of KFs were analyzed by CCK-8, EdU labeling, and TUNEL assays. Conditioned medium of KFs was collected to stimulate angiogenesis of human umbilical vein endothelial cells (HUVECs). Binding between miR-7846-3p and neuropilin 2 (NRP2) was validated by luciferase assay. Protein levels of NRP2 and the Hedgehog pathway molecules were analyzed by western blot analysis.

RESULTS

miR-7846-3p was predicted as an exosomal miRNA aberrantly expressed in keloids. AdMSC-Exos reduced viability, proliferation, and apoptosis resistance of KFs, and they blocked the angiogenesis of HUVECs. miR-7846-3p targeted NRP2 mRNA. miR-7846-3p upregulation in KFs suppressed NRP2 expression and reduced the expression of Hedgehog pathway molecules SHH, SMO, and GLI1. Either miR-7846-3p inhibition in Exos or NRP2 overexpression in KFs blocked the effects of Exos and restored the viability, proliferation, and pro-angiogenic role of KFs.

CONCLUSION

This work unravels that adMSC-Exos-derived miR-7846-3p suppresses NRP2 and inactivates the Hedgehog signaling to reduce proliferation and pro-angiogenic role of KFs.

Concentration-Dependent Inhibition of Hypertrophic Scar Formation by Botulinum Toxin Type A in a Rabbit Ear Model

BACKGROUND

Hypertrophic scar (HS), as a disappointing result of wound healing, adversely affects the patient, both physically and psychologically. Botulinum toxin type A (BTXA) has been revealed to prevent and improve HS. We conducted this study to assess the effect of different BTXA concentrations on inhibiting HS in a rabbit ear model.

METHODS

Eight healthy New Zealand long-eared rabbits were included in the experiment for modeling. Four wounds of 1 cm in diameter were created on both ears, which separately received an injection of a given BTXA concentration immediately after surgery. On postoperative days 40, scar tissue was obtained and subjected to hematoxylin and eosin (HE) staining for the hypertrophic index (HI) and immunohistochemical staining for CD31, Ki67, and transforming growth factor-beta 1 (TGF-β1) expression. The HI was assessed for scar proliferation, and CD31 and Ki67 expression were used to assess the effect of BTXA on angiogenesis and fibroblast proliferation, respectively.

RESULTS

All rabbits healed well without infection or mortality. From the HE staining, the HI showed a significant decrease with increasing BTXA concentration (p < 0.05). BTXA also inhibited angiogenesis and TGF-β1 expression in a concentration-dependent manner, with significant differences between the groups (p < 0.05). BTXA inhibited fibroblast proliferation with increasing BTXA concentration. However, there was no significant difference between the 0.5 U/0.1 ml and 0 U/0.1 ml groups (p > 0.05).

CONCLUSION

Immediate postoperative BTXA injection inhibited angiogenesis, fibroblast proliferation, and TGF-β1 expression in a concentration-dependent manner, thus suppressing HS formation in rabbit ears.

NO LEVEL ASSIGNED

This journal requires that authors assign a level of evidence to each submission to which Evidence-Based Medicine rankings are applicable. This excludes Review Articles, Book Reviews, and manuscripts that concern Basic Science, Animal Studies, Cadaver Studies, and Experimental Studies. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors https://www.springer.com/journal/00266 .