Intramural injection with botulinum toxin significantly elongates the pig esophagus

Botulinum Toxin Enhanced Foker Process for Long Gap Esophageal Atresia

BACKGROUND

The traction-induced esophageal growth (Foker) process for the treatment of long gap esophageal atresia (LGEA) relies on applying progressive tension to the esophagus to induce growth. Due to its anti-fibrotic and muscle-relaxing properties, we hypothesize that Botulinum Toxin A (BTX) can enhance traction-induced esophageal growth.

METHODS

A retrospective two-center cohort study was conducted on children who underwent a BTX-enhanced Foker process for LGEA repair from 2021 to 2023. BTX (10 units/ml, 2 units/kg, per esophageal pouch) was applied at the time of traction initiation. Time on traction, complications, and anastomotic outcomes were compared against historical controls (Foker process without BTX) from 2014 to 2021.

RESULTS

Twenty infants (LGEA type A:12, B:4, C:4; 35% reoperative; median [IQR] age 3 [2-5] months), underwent BTX-enhanced Foker process (thoracotomy with external traction: 9; minimally invasive [MIS] multi-staged internal traction: 11). Mean gap lengths were similar between BTX-enhanced external and external traction control patients (mean [SD], 50.6 mm [12.6] vs. 44.5 mm [11.9], p = 0.21). When compared to controls, the BTX-enhanced external traction process was significantly faster (mean [SD], 12.1 [1.6] days vs. 16.6 [13.2] without BTX, p = 0.04) despite similar preoperative gap lengths. There was no difference in time on traction for those undergoing a minimally invasive process. There were no significant differences in complications or anastomotic outcomes in either cohort.

CONCLUSION

Botulinum toxin may play a role in accelerating the traction-induced esophageal growth process for LGEA repair. Minimizing time on traction can decrease sedation and paralysis burden while on external traction. Further studies are needed to elucidate the effects of BTX on the esophagus.

LEVEL OF EVIDENCE

Level III.

TYPE OF STUDY

Retrospective, Two-center, Cohort study.

Therapeutic Applications of Botulinum Neurotoxins in Veterinary Medicine

Botulinum neurotoxins (BoNTs) are emerging as multipurpose therapeutic compounds for the treatment of several different syndromes involving peripheral and central nervous systems, and muscular and musculoskeletal disorders both in human and veterinary medicine. Therefore, the study of BoNTs is rapidly developing and identifying newly produced BoNT variants. Efforts should be made to clarify the biological and pharmacological characteristics of these novel BoNTs as well as the natural ones. The high potential of BoNTs as a therapeutic compound for medical syndromes lies in its ability to reach a specific cell type while bypassing other cells, thus having mild or no side effects. In this paper the recent developments in BoNTs are reviewed with the aim of analyzing the current knowledge on BoNTs' biological mechanisms of action, immunogenicity, formulations, and therapeutic applications in the veterinary field, highlighting advantages and drawbacks and identifying the gaps to be filled in order to address research priorities.

Endoscopic Injections of Botulinum Toxin Type A in the Piglet Esophagus Is Safe and Feasible but Did Not Result in any Significant Structural Changes 3 Days after Injection

INTRODUCTION

 Treatment for long-gap esophageal atresia (LGEA) aims at achieving primary anastomosis with minimal tension. Previous studies have shown that intramural injections with botulinum toxin type-A (BTX-A) from the adventitial side can increase the elongation of the piglet and rat esophagus before bursting, and that this effect is dose and time dependent. Our aim was to determine if endoscopic injections would be feasible, safe, and with an effect on the mechanical properties of the esophagus.

METHODS

 Twenty-two male piglets (5.15 kg) were randomized into two groups, one receiving 2 units/kg BTX-A, the other equal volume 0.9% NaCl. On day 3, the esophagus was harvested and tested in a stretch-tension machine to evaluate elongation and maximum load, followed by histological examination.

RESULTS

 No adverse effects to the procedure were observed. No statistically significant difference in elongation or maximum load before bursting between the treatment and placebo group was found. In histopathological analysis, inflammation and abscess formation were observed with no statistically significant difference between the two groups.

CONCLUSION

 Endoscopic placement of BTX-A injections in the piglet esophagus was safe and feasible but did not result in any difference in the mechanical properties or histology of the esophagus.

The Effect of Botulinum Toxin Type A Injections on Stricture Formation, Leakage Rates, Esophageal Elongation, and Anastomotic Healing Following Primary Anastomosis in a Long- and Short-Gap Esophageal Atresia Model - A Protocol for a Randomized, Controlled, Blinded Trial in Pigs

BACKGROUND

Esophageal atresia (EA) is a congenital malformation affecting 1:3000-4500 newborns. Approximately 15% have a long-gap EA (LGEA), in which case a primary anastomosis is often impossible to achieve. To create continuity of the esophagus patients instead have to undergo lengthening procedures or organ interpositions; methods associated with high morbidity and poor functional outcomes. Esophageal injections of Botulinum Toxin Type A (BTX-A) could enable primary anastomosis and mitigate stricture formation through decreased tissue tension.

METHODS AND ANALYSIS

In this randomized controlled blinded animal trial, 24 pigs are divided into a long- or short-gap EA group (LGEA and SGEA, respectively) and randomized to receive BTX-A or isotonic saline injections. In the LGEA group, injections are given endoscopically in the esophageal musculature. After seven days, a 3 cm esophageal resection and primary anastomosis is performed. In the SGEA group, a 1 cm esophageal resection and primary anastomosis is performed, followed by intraoperative injections of BTX-A or isotonic saline. After 14 days, stricture formation, presence of leakage, and esophageal compliance is assessed using endoscopic and manometric techniques, and in vivo and ex vivo contrast radiography. Tissue elongation is evaluated in a stretch-tension test, and the esophagus is assessed histologically to evaluate anastomotic healing.

ETHICS AND DISSEMINATION

The study complies with the ARRIVE guidelines for animal studies and has been approved by the Danish Animal Experimentation Council. Results will be published in peer-reviewed journals and presented at national and international conferences.

HIGHLIGHTS

The optimal management of long-gap esophageal atresia remains controversialPrimary anastomosis could improve functional outcomes and reduce complicationsBotulinum Toxin Type A decreases tissue tension and could facilitate anastomosisReduced tension could further abate the risk for anastomotic stricture and leakageWe present a model to evaluate the method in long- and short-gap esophageal atresia.

Intramural Injection of Botulinum Toxin A in Surgical Treatment of a Long Gap Esophageal Atresia-Rat Model

INTRODUCTION

 Anastomosis with minimal tension is desirable in long-gap esophageal atresia. Prior studies in piglets showed that intraesophageal injection of botulinum toxin type A (BTX-A) results in significant esophageal elongation. Our aim was to determine the BTX-A dose, number of injections, and time necessary to elicit maximal response.

MATERIALS AND METHODS

 Adult male Wistar rats (n = 48) were randomly assorted into five groups. Four treatment groups received 2 or 4 U/kg of BTX-A, delivered using two or four injections, and a control group received 0.9% NaCl. Esophagus was removed 6 or 24-hours postinjection and tested ex vivo using a stretch tension device. Subsequently, an optimal dose and time following injection was used to study the effects of BTX-A on anastomotic healing in vivo. Rats (n = 12) received an intraesophageal injection of BTX-A or 0.9% NaCl, followed by resection of 0.5 cm of esophagus and end-to-end anastomosis. Rats were observed for 9 days, and esophagus was removed for gross and histological evaluation.

RESULTS

 The largest effect on elongation was recorded in the BTX-A (2 U/kg) 24 hour, four injection group. In the anastomosis study, stricture formation was observed in all animals in the control group. Absence of esophageal stricture was found in three out of four animals in the treatment group macroscopically and histologically.

CONCLUSION

 We found that BTX-A exerts a positive effect on stretch characteristics of esophageal tissue in rats at 2 U/kg via four-injection delivery and 24-hour waiting period. This study suggests that BTX-A might improve anastomotic healing.

Impact of botulinum toxin A injection on esophageal anastomosis in a rabbit model

PURPOSE

The management of esophageal atresia is established, but the rate of postoperative complications remains high. We focused on a new, recently reported method of esophageal elongation using botulinum toxin type A (BTX-A) and evaluated the efficacy of BTX-A injection around esophageal anastomoses with tension in a rabbit model.

METHODS

Twenty rabbits aged 8-10 weeks and weighing 1.27-1.72 kg underwent resections of the esophagus measuring 1.5 cm long using an anterior cervical approach. Esophagoesophagostomies were performed after intramural administration of Xeomin™ (3 U/body) in the BTX-A group and saline in the control group. Morphological and histological evaluations were examined on postoperative day 14.

RESULTS

Six rabbits in each group survived. The BTX-A group showed significantly less postoperative anastomotic stricture and less fibrosis than the control group. Changes in wall thickness on both sides of the anastomotic areas were equivalent between the two groups, and no muscle fracturing was observed.

CONCLUSION

Local administration of BTX-A for esophagoesophagostomy significantly reduced postoperative anastomotic stricture with less fibrosis than that observed in the control group. Reduced anastomotic tension with BTX-A presumably contributed to better anastomotic healing. Determining the optimum dose of BTX-A is necessary for clinical application.

Differential response of pig masseter to botulinum neurotoxin serotypes a and b

INTRODUCTION

Pigs respond to direct administration of botulinum neurotoxins (BoNTs), although they are resistant to botulism. The human masseter is frequently targeted for BoNT therapy. We aimed to understand how BoNT affects chewing by injecting porcine masseters.

METHODS

One masseter of minipigs was injected with BoNT serotype A or B at doses comparable to those used in humans. Masticatory function was evaluated electromyographically. Muscle force was measured during tetany. Four weeks after injection, strain gauges affixed to the mandible assessed bone strain during chewing. Masseter mass and fiber diameter were measured after euthanasia.

RESULTS

BoNT-A had no measurable effect. In contrast, BoNT-B reduced electrical activity and muscle force, producing substantial asymmetry between injected and uninjected muscles.

CONCLUSIONS

The pig masseter is highly resistant to direct injection of BoNT-A, but it is affected by BoNT-B.