Thermo-sensitive isopentane aerification for mucosal lift during endoscopic resection in animal models (with video)

Potential of temperature-response collagen-genipin sol as a novel submucosal injection agent for endoscopic resection: Acute and chronic phase study using living animals

OBJECTIVES

We proposed a novel temperature-response collagen sol as a submucosal injection agent for endoscopic resection (ER) using pepsin-solubilized collagen (PSC) and genipin (Ge) in a prior study. This study aimed to evaluate the usefulness and safety of the sol (PSC/Ge) in acute and chronic phase experiments using living animals.

METHODS

In experiment 1, we performed endoscopic submucosal dissection (ESD) for six pigs using normal saline (NS), sodium hyaluronate (SH), and PSC/Ge. We compared the required amount of each agent per unit area and procedure time. In experiment 2, we created artificial ulcers with endoscopic mucosal resection (EMR) for five pigs using NS and PSC sol. We compared the artificial ulcer residual rate at 7 and 14 days after EMR, and the scarring rate at 14 days after EMR.

RESULTS

The required amount of agents per unit area for PSC/Ge (0.8 ± 0.8 mL/cm² ) and SH (1.1 ± 0.8 mL/cm² ) were significantly smaller than that for NS (1.8 ± 0.7 mL/cm² ). The total procedure time did not have a statistical difference. The artificial ulcer residual rates were 47.3 ± 0.7% for NS and 40.3 ± 0.7% for PSC/Ge on day 7 (P = 0.51), and 15.0 ± 0.1% for NS and 10.2 ± 0.1% for PSC/Ge sol on day 14 (P = 0.35). The scarring rate on day 14 was 10% for NS and 20% for PSC/Ge.

CONCLUSION

We demonstrated the feasibility of a novel temperature-response collagen gel as a submucosal injection agent for ER in the acute and chronic phase animal experiment.

Closure of gastric perforations during endoluminal resection using a novel biodegradable collagen sol: A feasibility survival study on porcine model (with video)

OBJECTIVE

A prior study using porcine colon demonstrated the feasibility of a novel injectable, temperature?responsive, and biodegradable collagen sol (ICS) that transforms from a liquid to a gel state in response to body temperature for endoscopic closure of perforation during endoscopic resection (ER). This study aims to report the acute and survival outcomes of ICS for gastric perforations during ER.

METHODS

In two experiments using nine live pigs under general anesthesia, four and six perforations (3-5\xA0mm) were created using an electrosurgical knife in acute and survival experiments, respectively. ICS was delivered to the perforations using an endoscopic catheter. In Experiment 1, a leak test and histopathology were performed on all explanted stomachs after euthanization. In Experiment 2, perforation sites were assessed by gastroscopy and histopathology 7, 14 and 28\xA0days post?

RESULTS

In Experiment 1, gastroscopy confirmed complete closure of the perforations with ICS and no evidence of leak. Subsequent histopathology revealed a fixation of collagen gel (CG) as a sealant agent at the perforation sites. There were no adverse effects related with ESD or the use of ICS. In Experiment 2, histopathology revealed a fixation of CG as a sealant agent, replacement with granulation tissue and no CG; and fibrotic tissue at 7, 14 and 28\xA0days, respectively.

CONCLUSIONS

This study presents a novel method using ICS, demonstrating promising efficacy and safety profile for endoscopic closure of perforations during ER. Further studies are necessary before translating to clinical use.

Efficacy and safety of a novel submucosal injection solution for endoscopic resection in porcine models

OBJECTIVE

A submucosal injection is usually required to improve the efficacy and safety of endoscopic submucosal dissection (ESD) and endoscopic mucosal resection (EMR). This study aimed to evaluate the performance of 3.3% sodium carboxymethyl starch (Na-CMS) solution, a novel submucosal injection solution, for ESD and EMR.

METHODS

Na-CMS, normal saline (NS) and two commercially available agents (sigMAVisc and Eleview) were injected into the esophageal submucosa of randomly grouped pigs. The level of submucosal elevation was examined. Subsequently, ESD or EMR procedures using 3.3% Na-CMS or NS as submucosal injections were performed in the gastrointestinal tract of the pigs.

RESULTS

Submucosal elevation was significantly higher and more sustained in the 3.3% Na-CMS group than in the controls (P < 0.05). The volume required for ESD or EMR was significantly lower in the 3.3% Na-CMS group than in the NS group (ESD: 12.21 ± 4.09 mL vs 28.25 ± 8.02 mL, P < 0.001; EMR: 3.99 ± 1.98 mL vs 7.15 ± 3.67 mL, P = 0.001). The ESD resection time was significantly shorter in the 3.3% Na-CMS group than in the NS group (16.58 ± 7.30 min vs 25.29 ± 11.89 min, P = 0.004). Hemorrhage after ESD in the 3.3% Na-CMS group was less severe than that in the NS group (P = 0.006).

CONCLUSION

3.3% Na-CMS is an effective, safe and low-cost submucosal injection solution and holds promise as preferable agent for submucosal injection in ESD and EMR procedures.

Potential of temperature-response collagen-genipin sols as a novel submucosal injection material for endoscopic resection

Background and study aims  We developed a novel submucosal (SM) injection material that contained pepsin-solubilized collagen (PSC), genipin (Ge) and phosphate buffer (PB). The aim of this study was to validate safety and usability of it for endoscopic resection (ER). Materials and methods  In preliminary studies, 1) appropriate warming time and concentration of Ge, and concentration of NaCl in PB, 2) storage modulus of PSC, Ge, and PB mixture (PSC/Ge), and PSC as a mechanical property, 3) histological finding after injection, and histological toxicity of PSC/Ge was evaluated. We injected PSC/Ge, PSC, sodium hyaluronate (SH), dextrose (DW), and normal saline (NS) into SM of resected porcine stomach. We compared mean height of mucosal elevation after immediate injection (MH) and mean retaining rate at 60 minutes (MR) as ex vivo study. Results  Optimal condition of PSC/Ge was Ge 5.5 mMol with 24 hours worming time and NaCl 280 mMol. PSC/Ge had better mechanical property than PSC. It was efficiently integrated and confined to the SM with acceptable toxicity. MH of PSC/Ge (5.1 ± 0.74 mm) and PSC (4.8 ± 0.84 mm) were significantly higher than NS (3.2 ± 0.84 mm). MR of PSC/Ge (100 ± 0.0%) was significantly higher than NS (61.7 ± 11.2%), DW (58.3 ± 11.8%) and SH (61.8 ± 8.6%). Conclusion  PSC/Ge and PSC has potential to be safe and usable for ER. PSC/Ge was better than PSC because of better mechanical property than PSC.

A novel injectable thermo-sensitive binary hydrogels system for facilitating endoscopic submucosal dissection procedure

Background and aims

Making an optimal and lasting submucosal cushion is critical for endoscopic submucosal dissection. The thermo-sensitive binary hydrogels system composed of poloxamer 407 and poloxamer 188 might be an excellent submucosal injection solution considering the unique feature that it remains liquid at room temperature and becomes gelatinous after being injected in the submucosa of the digestive tract. The present study focuses on preparing the thermo-sensitive binary hydrogels system and testing its capacity in mucosal lifting and its role in the endoscopic submucosal dissection procedure.

Methods

Various concentrations of poloxamer 407 and poloxamer 188 were added to normal saline. The gelation temperature viscosity of the thermo-sensitive binary hydrogels system was measured to choose the best formula. The thermo-sensitive binary hydrogels system and normal saline were first compared in extracted porcine stomach. For in vivo study, the thermo-sensitive binary hydrogels system and normal saline were compared for facilitating the endoscopic submucosal dissection procedure.

Results

Among the 46 kinds of thermo-sensitive binary hydrogels system, gelation temperatures of the thermo-sensitive binary hydrogels system I (poloxamer 407/poloxamer 188, 17%/0.5%, w/w) and the thermo-sensitive binary hydrogels system II (poloxamer 407/poloxamer 188, 18%/2%, w/w) were among the ideal range of gelation temperature. The injecting pressure in vitro study of thermo-sensitive binary hydrogels system II was significantly higher than that of thermo-sensitive binary hydrogels system I and normal saline (p < 0.001). Sixteen gastric endoscopic submucosal dissection procedures were performed in a porcine model. The initial volume of normal saline injection (13.88 ± 3.91 ml vs 5.88 ± 3.44 ml, p = 0.001) was significantly larger than the thermo-sensitive binary hydrogels system group. The postoperative wound showed a significant difference in the two groups (p = 0.023) indicating that the thermo-sensitive binary hydrogels system can create a cleaner wound.

Conclusions

Considering the gelation temperature, viscosity, injection pressure, and the height of the mucosal elevation, the thermo-sensitive binary hydrogels system I was the better submucosal injection solution.

Thermoresponsive aerification and tissue vacuolization for facilitating endoscopic submucosal resection

BACKGROUND AND AIMS

Mucosal lifting and its persistence are critical for maintaining the operational space and preventing perforation in endoscopic operation. Although numerous agents have been investigated, optimization is still required for improving their clinical performance. In the present study, we proposed a novel concept of thermoresponsive aerification and tissue vacuolization for submucosal injection.

METHODS

Lifting performance and operational condition were first evaluated in porcine stomachs in vitro and rabbits in vivo. Dodecafluoropentane (DDFP) injection dosage, lifting persistency and operational assistance were quantitatively recorded. Gross and histological pathology were also analyzed to identify DDFP acute toxicity and long-term safety. The endoscopic submucosal dissection (ESD) procedure with DDFP was carried out on pigs in vivo to confirm its operational feasibility, efficacy, and safety.

RESULTS

Dodecafluoropentane aerification could achieve better mucosal lift with lower dosage (1% of normal saline dosage). Thermoresponsive DDFP aerification could provide continuous replenishment and longer persistence. Meanwhile, its tissue vacuolization effect significantly facilitated submucosal tissue dissection in in vitro study. Similar performance was verified in vivo. The particular vacuole-like submucosal structure was seen after DDFP onset, which also promoted reepithelization and wound healing. No tissue damage, gas embolism, biotoxicity, and physicochemical risk were observed.

CONCLUSION

Bioinert DDFP was feasible, efficient, and safe as the novel submucosal lifting candidate.