Comparative study on the establishment efficacy of four types of animal models of rectovaginal fistula in rabbits.

Various surgical methods have so far been developed for treating rectovaginal fistula (RVF), each with its own advantages and disadvantages. The lack of standardized animal models of RVF is a major reason for the failure to establish a unified and effective surgical method for the treatment of RVF. This study aimed to explore the feasibility of an RVF animal model by magnetic compression and compare it with the traditional modeling method. Thirty-two female Japanese white rabbits were randomly divided into four groups: A, B, C, and D, based on how the rectovaginal septum was treated. The operation time, intraoperative blood loss, and model success rate of each group were determined. The experimental animals were euthanized 2 weeks after the operation. Their rectovaginal septum specimens were obtained. RVF was observed by the naked eye. The fistula size was measured. Histological changes of fistula were observed by hematoxylin and eosin and Masson staining. All rabbits completed the RVF model and survived 2 weeks after the operation. Groups A and B had no bleeding, while groups C and D had < 0.5 mL of bleeding. The magnet detached in 4-6 days in group A, while it remained in place for 2 weeks after surgery in group B. Only one group D rabbit had a plastic hose for 2 weeks after surgery. The RVFs of groups A and C healed by themselves. In group B, the fistula was well formed. In group D, fistula healing was observed in three animals and the diameter of the fistulas was only 2.82-4.64 mm in the other four animals. Groups B and D had a scar on the inner surface of fistulas. Our study shows that the magnetic compression technique based on the T-shaped magnet is a highly useful method to establishing a continuous and stable RVF model in rabbits.

Feasibility experiment of a novel deformable self-assembled magnetic anastomosis ring (DSAMAR) for gastrointestinal anastomosis through a natural orifice.

Although the application of magnetic compression anastomosis is becoming increasingly widespread, the magnets used in earlier studies were mostly in the shape of a whole ring. Hence, a deformable self-assembled magnetic anastomosis ring (DSAMAR) was designed in this study for gastrointestinal anastomosis. Furthermore, its feasibility was studied using a beagle model. The designed DSAMAR comprised 10 trapezoidal magnetic units. Twelve beagles were used as animal models, and DSAMARs were inserted into the stomach and colon through the mouth and anus, respectively, via endoscopy to achieve gastrocolic magnamosis. Surgical time, number of failed deformations, survival rate of the animals, and the time of magnet discharge were documented. A month later, specimens of the anastomosis were obtained and observed with the naked eye as well as microscopically. In the gastrocolic anastomosis of the 12 beagles, the procedure took 65-120 min. Although a deformation failure occurred during the operation in one of the beagles, it was successful after repositioning. The anastomosis was formed after the magnet fell off 12-18 days after the operation. Naked eye and microscopic observations revealed that the anastomotic specimens obtained 1 month later were well-formed, smooth, and flat. DSAMAR is thus feasible for gastrointestinal anastomosis under full endoscopy via the natural orifice.

Optimization of tracheoesophageal fistula model established with T-shaped magnet system based on magnetic compression technique.

BACKGROUND: The magnetic compression technique has been used to establish an animal model of tracheoesophageal fistula (TEF), but the commonly shaped magnets present limitations of poor homogeneity of TEF and poor model control. We designed a T-shaped magnet system to overcome these problems and verified its effectiveness via animal experiments. AIM: To investigate the effectiveness of a T-shaped magnet system for establishing a TEF model in beagle dogs. METHODS: Twelve beagles were randomly assigned to groups in which magnets of the T-shaped scheme (study group, n = 6) or normal magnets (control group, n = 6) were implanted into the trachea and esophagus separately under gastroscopy. Operation time, operation success rate, and accidental injury were recorded. After operation, the presence and timing of cough and the time of magnet shedding were observed. Dogs in the control group were euthanized after X-ray and gastroscopy to confirm establishment of TEFs after coughing, and gross specimens of TEFs were obtained. Dogs in the study group were euthanized after X-ray and gastroscopy 2 wk after surgery, and gross specimens were obtained. Fistula size was measured in all animals, and then harvested fistula specimens were examined by hematoxylin and eosin (HE) and Masson trichrome staining. RESULTS: The operation success rate was 100% for both groups. Operation time did not differ between the study group (5.25 min ± 1.29 min) and the control group (4.75 min ± 1.70 min; P = 0.331). No bleeding, perforation, or unplanned magnet attraction occurred in any animal during the operation. In the early postoperative period, all dogs ate freely and were generally in good condition. Dogs in the control group had severe cough after drinking water at 6-9 d after surgery. X-ray indicated that the magnets had entered the stomach, and gastroscopy showed TEF formation. Gross specimens of TEFs from the control group showed the formation of fistulas with a diameter of 4.94 mm ± 1.29 mm (range, 3.52-6.56 mm). HE and Masson trichrome staining showed scar tissue formation and hierarchical structural disorder at the fistulas. Dogs in the study group did not exhibit obvious coughing after surgery. X-ray examination 2 wk after surgery indicated fixed magnet positioning, and gastroscopy showed no change in magnet positioning. The magnets were removed using a snare under endoscopy, and TEF was observed. Gross specimens showed well-formed fistulas with a diameter of 6.11 mm ± 0.16 mm (range, 5.92-6.36 mm), which exceeded that in the control group (P < 0.001). Scar formation was observed on the internal surface of fistulas by HE and Masson trichrome staining, and the structure was more regular than that in the control group. CONCLUSION: Use of the modified T-shaped magnet scheme is safe and feasible for establishing TEF and can achieve a more stable and uniform fistula size compared with ordinary magnets. Most importantly, this model offers better controllability, which improves the flexibility of follow-up studies.

Laparoscopic-assisted full-sized liver transplantation with magnetically fast portal vein anastomosis: An initial cohort study.

BACKGROUND: Some cases of laparoscopic-assisted liver transplantation (LA-LT) with utilization of reduced-size grafts has been reported. We here introduced successful utilization of LA-LT with whole liver grafts and magnetic portal vein anastomosis. METHODS: Eight patients with liver cirrhosis were included for LA-LT using donor organs after cardiac death. The surgical procedures included purely laparoscopic explant hepatectomy and whole-liver graft implantation via the midline incision. After explant removal, the whole-liver graft was then placed in situ, and a side-to-side cavo-caval anastomosis with 4-5 cm oval opening was performed. The magnetic rings were everted on the donor and recipient portal vein, respectively, and the instant attachment of the two magnets at the donor and recipient portal vein allowed fast blood reperfusion, followed by continuous suturing on the surface of the magnets. RESULTS: The median operation time was 495 (range 420-630). The median time of explant hepatectomy and IVC anastomosis was 239 (range 150-300) min and 14.5 (range 10-19) min, respectively. Of note, the median anhepatic time was 25 (range 20-35) min. All the patients were discharged home with no major complications after more than six months follow-up. CONCLUSION: LA-LT with full-size graft is feasible and utilization of magnetic anastomosis would further simplify the procedure.

Enhanced hemocompatibility and rapid magnetic anastomosis of electrospun small-diameter artificial vascular grafts.

Background: Small-diameter (<6 mm) artificial vascular grafts (AVGs) are urgently required in vessel reconstructive surgery but constrained by suboptimal hemocompatibility and the complexity of anastomotic procedures. This study introduces coaxial electrospinning and magnetic anastomosis techniques to improve graft performance. Methods: Bilayer poly(lactide-co-caprolactone) (PLCL) grafts were fabricated by coaxial electrospinning to encapsulate heparin in the inner layer for anticoagulation. Magnetic rings were embedded at both ends of the nanofiber conduit to construct a magnetic anastomosis small-diameter AVG. Material properties were characterized by micromorphology, fourier transform infrared (FTIR) spectra, mechanical tests, in vitro heparin release and hemocompatibility. In vivo performance was evaluated in a rabbit model of inferior vena cava replacement. Results: Coaxial electrospinning produced PLCL/heparin grafts with sustained heparin release, lower platelet adhesion, prolonged clotting times, higher Young's modulus and tensile strength versus PLCL grafts. Magnetic anastomosis was significantly faster than suturing (3.65 ± 0.83 vs. 20.32 ± 3.45 min, p < 0.001) and with higher success rate (100% vs. 80%). Furthermore, magnetic AVG had higher short-term patency (2 days: 100% vs. 60%; 7 days: 40% vs. 0%) but similar long-term occlusion as sutured grafts. Conclusion: Coaxial electrospinning improved hemocompatibility and magnetic anastomosis enhanced implantability of small-diameter AVG. Short-term patency was excellent, but further optimization of anticoagulation is needed for long-term patency. This combinatorial approach holds promise for vascular graft engineering.

Fabrication of Decellularized Spleen Matrix Derived from Rats.

Liver transplantation is the primary treatment for end-stage liver disease. However, the shortage and inadequate quality of donor organs necessitate the development of alternative therapies. Bioartificial livers (BALs) utilizing decellularized liver matrix (DLM) have emerged as promising solutions. However, sourcing suitable DLMs remains challenging. The use of a decellularized spleen matrix (DSM) has been explored as a foundation for BALs, offering a readily available alternative. In this study, rat spleens were harvested and decellularized using a combination of freeze-thaw cycles and perfusion with decellularization reagents. The protocol preserved the microstructures and components of the extracellular matrix (ECM) within the DSM. The complete decellularization process took approximately 11 h, resulting in an intact ECM within the DSM. Histological analysis confirmed the removal of cellular components while retaining the ECM's structure and composition. The presented protocol provides a comprehensive method for obtaining DSM, offering potential applications in liver tissue engineering and cell therapy. These findings contribute to the development of alternative approaches for the treatment of end-stage liver disease.

Application of Y-Z deformable magnetic ring for recanalization of transanal single-access rectal stricture.

Magnetic compression anastomosis has been reported to have remarkable clinical outcomes. Here, we tested the applicability of a Y-Z deformable magnetic ring (DMR) for non-surgical manipulation of rectal stenosis (RS) in a beagle dog model under a transanal single-access condition. RS was modeled in 8 beagle dogs using partial ligation with silk thread. Under X-ray guidance, the Y-Z DMR was positioned at the proximal and distal ends of the RS, and the magnetic ring was bent into an "O" shape, such that the two rings were magnetically attracted. Operation time, complications during or after operation, and discharge time of the magnetic rings were recorded. The anastomosis bursting pressure was measured two weeks after removing the rings, and its formation was assessed through gross and histological examination. Partial ligation with a silk thread successfully established the canine RS model. After Y-Z DMR installation, the magnetic ring was successfully reconfigured from an "S" to an "O" shape. Strong attraction existed between the rings. The operation time was 9-15 min (average: 11.75 ± 1.98 min). No rectal bleeding or perforation occurred during or after operation. The ring was naturally expelled 7-10 days after surgery. A pressure of > 300 mmHg was recorded at the point of anastomosis rupture. The rectal anastomosis appeared to have healed properly on the surface, which was confirmed histologically, signifying the success of this procedure. A Y-Z DMR facilitated the successful recanalization of transanal single-channel RS without needing surgery in an animal model.

Liver transplantation using magnetic anastomosis in pigs.

Magnetic anastomosis substantially shortens the duration of vascular anastomosis. We aimed to apply magnetic anastomosis technology (MAT) to donor liver implantations in pig orthotopic liver transplantation (OLT). Twenty healthy adult pigs were randomly divided into donors and recipients, and major vascular anastomosis was performed using MAT during OLT. Recipient liver and kidney function was measured pre-surgery and 12, 24 and 72 h post-surgery. Vascular anastomoses examinations were performed using ultrasound or angiography weekly post-surgery, and pathological examinations of vascular anastomoses were performed during autopsy after animal euthanasia. All recipients survived 24 h after surgery, which is considered as successful transplantation. Anhepatic duration was only 13 min, and no anastomotic obstruction or stenosis, magnetic displacement and anastomotic angulation, or distortion was found upon postoperative examinations of major liver vasculature. Aspartate aminotransferase, alanine aminotransferase, and total bilirubin serum levels increased considerably postoperatively. The follow-up period for this study was 1 year, and the median survival time of all recipients was 115 d (interquartile range = 11-180 d). The main causes of death were liver failure, immune rejection, infection, and arterial anastomotic bleeding. Moreover, vascular anastomoses healed well with a survival time of more than two weeks. We developed a novel magnetic device to create a fast and safe technique to perform major vascular anastomoses in pig liver transplantations. Additionally, the liver graft implantation using MAT considerably shortened the recipient warm ischemia time, which will reduce the extent of ischemia-reperfusion injury. We conclude that MAT is an effective method for donor liver fast implantation in OLT in pigs.

Value of a novel Y-Z magnetic totally implantable venous access port in improving the success rate of one-time needle insertion.

Background and objectives: A totally implantable venous access port (TIVAP) is a commonly used intravenous infusion device for patients receiving chemotherapy or long-term infusion therapy. To improve the success rate of one-time insertion of the Huber needle, we developed a novel Y-Z magnetic TIVAP (Y-Z MTIVAP), which we produced using three-dimensional printing technology. Materials and methods: The Y-Z MTIVAP includes a magnetic port body and a magnetic positioning device. For testing, we established four venous port implantation models using the two types of TIVAPs and two implantation depth ranges (≤5 mm and >5 mm). Twenty nurses performed Huber needle puncture with the four models, and we recorded the number of attempts required for successful needle insertion, the operation time, and the operator's satisfaction. Results: The success rate for one-time needle insertion with the Y-Z MTIVAP was significantly higher than that with the traditional TIVAP at either depth range (100% vs. 75% at ≤5 mm, p = 0.047; 95% vs. 35% at >5 mm, p < 0.001). With increasing implantation depth, the success rate for one-time insertion was significantly reduced with the traditional TIVAP (75% at ≤5 mm vs. 35% vs. >5 mm, p = 0.025), but the success rate with the Y-Z MTIVAP was not significantly affected (100% vs. 95%, p = 1.000). The operation time with the Y-Z MTIVAP was significantly shorter than that with the traditional TIVAP at either depth range (both p < 0.001), and 90% of operators reported that the Y-Z MTIVAP was superior to the traditional TIVAP. Conclusions: The theoretical design of Y-Z MTIVAP is feasible, and the preliminary in vitro simulation experiment shows that it can significantly improve puncture success rate and shortened operation time.

Novel deformable self-assembled magnetic anastomosis ring for endoscopic treatment of colonic stenosis via natural orifice.

BACKGROUND: Although endoscope-assisted magnetic compression anastomosis has already been reported for colonic anastomosis, there is no report on a single-approach operation using the natural orifice. AIM: To design a deformable self-assembled magnetic anastomosis ring (DSAMAR) for colonic anastomosis for use in single-approach operation and evaluate its feasibility and safety through animal experiments. METHODS: The animal model for colonic stenosis was prepared by partial colonic ligation in eight beagles. The magnetic compression anastomosis of their colonic stricture was performed by endoscopically assisted transanal implantation of the DSAMAR. The anastomotic specimen, obtained 2 wk after the operation, was observed by both the naked eye and a light microscope. RESULTS: The DSAMAR was successfully inserted into the proximal end of colon stenosis through the anus. The DSAMAR of seven dogs was successfully transformed into rings, while that of the remaining dog was removed after the first deformation failed. The rings were successfully retransformed after optimization. All animals underwent colonic anastomosis using the DSAMAR. No device-related or procedure-related adverse events were observed. The colostomy specimens of the experimental dogs were obtained 2 wk after the operation. Both gross and histological observations showed good anastomotic healing. CONCLUSION: The DSAMAR is a safe and feasible option for the treatment of colon stenosis. Its specific deformation and self-assembly capability maximize the applicability of the minimally invasive treatment.

Primary animal experiment to test the feasibility of a novel Y-Z magnetic hepatic portal blocking band.

BACKGROUND: Hepatic portal blood flow occlusion is a common technique for reducing hepatic hemorrhage during hepatectomy. We designed a novel Y-Z magnetic hepatic portal blocking band (Y-Z MHPBB) based on the principle of magnetic compression technique. AIM: To introduce the Y-Z MHPBB device and verify the feasibility of this device for hepatic portal blood flow occlusion in dogs. METHODS: Ten beagles were randomly divided into the experimental group and control group. The operation time, intraoperative blood loss, the number of portal blood flow occlusions, the total time spent on adjusting the blocking band, and the average time spent on adjusting the blocking band were recorded. The surgeons evaluated the feasibility and flexibility of the two portal occlusion devices. RESULTS: Laparoscopic hepatectomy was successfully performed in both the experimental group and control group. There was no statistical difference between the two groups in the operation time, intraoperative blood loss, and the number of hepatic portal blood flow occlusions. With respect to the total time spent on adjusting the blocking band and the average time spent on adjusting the blocking band, the experimental group showed significantly better outcomes than the control group, with a statistical difference (P < 0.05). The operators found that the Y-Z MHPBB was superior to the modified T-tube in terms of operational flexibility. CONCLUSION: The Y-Z MHPBB seems to be an ingenious design, accurate blood flow occlusion effect, and good flexibility; and it can be used for hepatic portal blood flow occlusion during laparoscopic hepatectomy.

Magnetic compression anastomosis for reconstruction of digestive tract after total gastrectomy in beagle model.

BACKGROUND: Magnetic compression anastomosis (MCA) is a simple procedure contributing to a reliable anastomosis. However, digestive-tract reconstruction after total gastrectomy using MCA has not yet been reported. AIM: To investigate the feasibility of MCA for simultaneous esophagojejunostomy and jejunojejunostomy after total gastrectomy using beagle dogs. METHODS: Sixteen beagles were randomly divided into an MCA group (study group, n = 8) and a manual-suture anastomosis group (control group, n = 8). Two different magnetic anastomosis devices were used in the study group for esophagojejunal and jejunojejunal anastomoses. Both devices included a pair of circular daughter and parent magnets each. The time of esophagojejunostomy and jejunojejunostomy, postoperative complications, and survival rate of the two groups were compared. The dogs were sacrificed one month after the operation and their anastomotic specimens were obtained. Healing was observed by the naked eye and a light microscope. RESULTS: Digestive-tract reconstruction after total gastrectomy was successfully completed in both groups (survival rate = 100%). In the study group, esophagojejunal and jejunojejunal anastomoses took 6.13 ± 0.58 and 4.06 ± 0.42 min, respectively, significantly lower than those in the control group (15.63 ± 1.53 min, P < 0.001 and 10.31 ± 1.07 min, P < 0.001, respectively). Complications such as bleeding, anastomotic leakage, and anastomotic stenosis were not observed. In the study group, the magnets did not interfere with each other. Discharge time of the jejunojejunal magnetic anastomosis device was 10.75 ± 1.28 d, while that of the esophagojejunal magnetic anastomosis device was 12.25 ± 1.49 d. Residual silk was found in the control group. The study group showed a greater smoothness of the anastomosis than that of the control group. All layers of anastomosis healed well in both groups. CONCLUSION: MCA is a safe and feasible procedure for digestive-tract reconstruction after total gastrectomy in this animal model.

An experimental study of magnetic compression technique for ureterovesical anastomosis in rabbits.

This study aimed to explore the feasibility of the magnetic compression technique (MCT) for ureterovesical anastomosis in a rabbit model with ureteral obstruction. The distal ureteral obstruction model using female New Zealand rabbits was induced by ligating the distal end of the right ureter with silk thread for four weeks. A pair of cylindrical NdFeB magnets (daughter magnet and parent magnet) with a hole in the center was used for the ureterovesical anastomosis. The daughter magnet and the parent magnet were respectively placed close to the obstruction site through the dilated proximal ureter and urethra, and then the daughter-parent magnets pair was attracted together automatically. Postoperative X-rays were taken to confirm the position of the magnets. The anastomotic stoma specimens were obtained two weeks postoperatively, and the anastomotic stoma formation was observed by the naked eye and histological staining. The operation time and the anastomotic burst pressure were measured. The ureter was significantly dilated in the fourth week after ligation, which satisfied the placement of the daughter magnet. The ureterovesical magnet placements were successfully performed in ten experimental rabbits, with an operation time of 36.5 ± 6.09 min. The parent and daughter magnets attracted each other well and were subsequently removed through the urethra two weeks postoperatively, resulting in the establishment of ureterovesical anastomosis. The anastomotic burst pressure was 147.5 ± 14.59 mmHg. Gross specimens and histological examination of the anastomotic stoma showed that the anastomotic stoma healed well. MCT is feasible and simple for ureterovesical anastomosis.

Magnetic anchor technique in laparoscopic cholecystectomy: a single-center, prospective, randomized controlled trial.

BACKGROUND: There have been no prospective randomized controlled clinical trials evaluating the advantages of the magnetic anchor technique (MAT) used in reduced-port laparoscopic cholecystectomy (LC). The present study evaluated a novel magnetic anchor device designed by the authors. METHODS: Between April 2019 and June 2020, 60 patients with gallbladder diseases participated in a single-center, prospective, randomized controlled clinical trial. The patients were randomly apportioned to undergo either 2-port LC assisted by the novel MAT (MAT-2P-LC, experimental group) or conventional 3-port LC (3P-LC, control). The groups were compared regarding operative time, postoperative complications, surgical incision pain score (Wong-Baker), and other indicators. The patients were followed for 2 years. RESULTS: The test and control groups were comparable in age, gender, body mass index, and primary disease. No patient in the MAT-2P-LC group was converted to 3P-LC. No patients were converted to laparotomy. On the first postoperative day, the Wong-Baker pain score of the experimental group (1.60 ± 0.67) was significantly lower than that of the control (2.20 ± 0.76; P = 0.002). The groups were statistically similar regarding intraoperative blood loss; operative time; time to leave bed; hospital stay; postoperative pain scores at 1 and 4 weeks; and complications. CONCLUSIONS: This rigorous clinical trial shows that the novel MAT used to assist reduced-port LC significantly reduced postoperative pain, but has no obvious advantages in other terms. Clinical Trails.gov. number, ChiCTR1800019464.

Magnetic anchor technique-assisted thoracoscopic lobectomy in beagles.

In single-port thoracoscopic lobectomy, surgical instruments are likely to collide and interfere with each other. We used magnetic anchor technique to design an anchoring device suitable for thoracoscopic surgery, and verified the safety and feasibility of its use in animal experiments. Ten Beagles were used as models, and magnetic anchor technology was used to assist thoracoscopic lobectomy. During the operation, a self-designed magnetic anchored internal grasper was used in place of the traditional laparoscopic grasping forceps. The operation time, intraoperative blood loss, incidence of postoperative complications, and the effect of intraoperative use of the device were analyzed. All 10 beagles were successfully operated; the mean operation time was 19.7 ± 3.53 min (range 15-26 min), and the postoperative blood loss was < 10 mL. No surgical complications occurred. During the operation, the internal grasper was firmly clamped, the auxiliary operation field was well exposed, and the interference of the main operation hole instruments was effectively reduced. We provide preliminary experimental evidence of the safety and feasibility of magnetic anchor technique-assisted thoracoscopic lobectomy.

A novel magnetic compression technique for cystostomy in rabbits.

Magnetic compression technique (MCT) is a popular new anastomosis method. In this paper, we aimed to explore the feasibility of use of MCT for performing cystotomy in rabbits. The parent magnets and daughter magnets for rabbit cystostomy were designed and manufactured according to the anatomical characteristics of rabbit lower urinary tract. Twelve female New Zealand rabbits were used as animal models. After anesthesia, a daughter magnet was inserted into the bladder through the urethra, and the parent magnet was placed on the body surface projection of the bladder over the abdominal wall. The two magnets automatically attract each other. Postoperatively, the state of magnets was monitored daily, and the time when the magnets fell off was recorded. Cystostomy with MCT was successfully performed in all twelve rabbits. The mean operation time was 4.46 ± 0.75 min. The magnets fell off from the abdominal wall after a mean duration of 10.08 ± 1.62 days, resulting in the formation of bladder fistula. Macroscopic and microscopic examination showed that the fistula was well formed and unobstructed. The junction between bladder and abdominal wall was tight and smooth. We provide preliminary experimental evidence of the safety and feasibility of cystostomy based on MCT.

Implementation of sodium alginate-Fe3O4 to localize undiagnosed small pulmonary nodules for surgical management in a preclinical rabbit model.

Many methods are used to locate preoperative small pulmonary nodules. However, deficiencies of complications and success rates exist. We introduce a novel magnetic gel for small pulmonary nodules localization in rabbit model, and furtherly evaluate its safety and feasibility. Rabbits were used as the experimental objects. A magnetic gel was used as a tracer magnet, mixed as sodium alginate-Fe3O4 magnetic fluid and calcium gluconate solution. In short-term localization, a coaxial double-cavity puncture needle was applied to inject the gel into the lung after thoracotomy, and a pursuit magnet made of Nd-Fe-B permanent magnetic materials was used to attract the gel representing location of the nodule. In long-term localization, the gel was injected under X-ray guidance. Imaging changes to the lung were observed under X-ray daily. Thoracotomy was performed to excise tissue containing the gel, and hematoxylin-eosin staining was used to observe the tissue on postoperative days 1, 3, 5, and 7. Observe tissues morphology of heart, liver, spleen, and kidney in the same way. The gel was formed after injection and drew lung tissue to form a protrusion from the lung surface under the applied magnetic field. No complication was observed. The shape and position of the gel had not changed when viewed under X-ray. Pathological analysis showed the gel had a clear boundary without diffusion of magnetic fluid. All tissues retained good histologic morphology and no magnetic fluid was observed. Our study preliminarily suggested that the technique using sodium alginate-Fe3O4 magnetic gel to locate small pulmonary nodules with guidance of X-ray, and to search for them under an applied magnetic field during the operation is safe and feasible.

Regional anticoagulation magnetic artificial blood vessels constructed by heparin-PLCL core-shell nanofibers for rapid deployment of veno-venous bypass.

Veno-venous bypass (VVB) is necessary for maintaining hemodynamic and internal environment stabilities in complex liver surgeries. However, the current VVB strategies require systematic anticoagulation and are time-consuming, leading to unexpected complications. This study aims to overcome these limitations by using a novel magnetic artificial blood vessel constructed with heparin-PLCL core-shell nanofibers. Coaxial electrospinning was used to fabricate core-shell nanofibers with heparin encapsulated into the core layer. The microstructure, physical and chemical properties, hemocompatibility, and heparin release behavior were characterized. The regional anticoagulation magnetic artificial vessel was constructed with these nanofibers and used to perform VVB in a rat liver transplantation model for in vivo evaluation. The core-shell nanofibers appeared smooth and uniform without apparent defects. Fluorescence and TEM images indicated that heparin was successfully encapsulated into the core layer. In addition, the in vitro heparin release test presented a two-phase release profile, burst release at day 1 and sustained release from days 2 to 14, which resulted in better hemocompatibility. The VVB could be rapidly deployed in 3.65 ± 0.83 min by the magnetic artificial vessel without systemic anticoagulation. Moreover, the novel device could reduce portal pressure and abdominal organ congestion, protect intestinal function, and increase the survival rate of liver transplantation with a long anhepatic phase from 0 to 65%. In summary, VVB can be rapidly deployed using regional anticoagulation magnetic artificial blood vessels without systemic anticoagulation, which is promising for improving patient outcomes after complex liver surgery.

Creation of gastroenteric anastomosis through natural orifice in rats by magnetic compression technique.

BACKGROUND: Being one of the core techniques of magnetic surgery, magnetic compression technique (MCT) has been used for digestive tract anastomosis reconstruction in experimental studies. This study verified the feasibility of gastroenteric anastomosis through natural orifice using MCT in rats. METHODS: The parent and daughter magnets were designed and manufactured for oral and anal insertion in 20 Sprague-Dawley rats. After anesthesia, the parent magnet was inserted into the colon spleen area through the anus, and the daughter magnet was inserted into the stomach through the mouth. Then the two magnets were positioned to attract each other and bind together. The position of the two magnets was monitored using X-ray. The time required for the formation of the anastomosis and expulsion of the magnets were recorded. 2 weeks later, the animal was sacrificed and the anastomotic specimen was obtained which was observed under naked eye and microscope. RESULTS: The gastroenteric anastomosis was successfully performed via natural orifices in 18 out of 20 rats. The mean time to construct the anastomosis was 3.78 ± 0.88 min. X-ray examination showed that the magnets were in the appropriate position in 17 rats. The magnets were excreted in 9.47 ± 1.62 days after surgery. The gross and microscopic examination of the specimen showed that the anastomoses were patent and the mucosa at the anastomotic was smooth. The mean bursting pressure of the anastomosis was 136.94 ± 6.79 mmHg. CONCLUSION: It is feasible to perform gastroenteric anastomosis through natural orifices by MCT.

Magnetic Compression Technique for Esophageal Anastomosis in Rats.

INTRODUCTION: The magnetic compression technique (MCT) is used for the anastomosis of hollow organs by the means of suction between magnets. The MCT is useful for establishing digestive tract anastomoses in rats, for example, end-to-side small intestinal anastomosis and colonic anastomosis. We aim to determine the feasibility of MCT-based esophageal anastomosis in rats. METHODS: Twenty-four Sprague-Dawley albino rats (230-250 g) were randomly divided into an MCT group and a control group (hand-sewn esophageal anastomosis). The time required to construct the anastomosis, postoperative complications, and survival rate was compared between the two groups. At 2 wk postoperatively, the animals were sacrificed to assess the burst pressure and histological features of the anastomoses. RESULTS: The mean anastomosis time was significantly lower for MCT (11.17 ± 1.64 min) than for the hand-sewn technique (27.42 ± 2.23 min; P < 0.001). The survival rate was slightly higher in the MCT group (91.67%) than in the control group (66.67%, P = 0.317). The magnets were discharged from the body after 8.33 ± 0.89 d (range, 7-10 d). No anastomotic leakage or stenosis occurred in the MCT group. Three rats developed anastomotic stenosis and two rats developed anastomotic leakage in the control group. The burst pressures were similar in the two groups. An histological examination showed that compared with the control group, the MCT group had better alignment of the tissue layers and less inflammation. CONCLUSIONS: The MCT is a simple and feasible technique for esophageal anastomosis in rats and has the potential for clinical application.