Distraction enterogenesis in the murine colon

Background/PurposeDistraction enterogenesis with intraluminal spring technology has been successfully used to lengthen segments of murine small intestine. We hypothesized that biocompatible springs could also be used to lengthen murine large intestine.MethodsAge and weight matched C57BL/6 mice underwent surgical insertion of nitinol spring-loaded capsules into the cecum. Segment lengths were measured at initial spring placement and at euthanasia after 7 and 14 days. Histologic adaptations were evaluated at scarification.ResultsCecal segments loaded with compressed springs lengthened an average of 150%, which was significantly longer than control segments loaded with either empty capsules or uncompressed springs. Muscularis layers tended to be thicker in the compressed spring groups compared to control groups.ConclusionsInsertion of a compressed nitinol spring into the cecum results in significant colonic lengthening in a mouse model. The ability to increase cecum length serves as proof of concept that distraction enterogenesis technology may be feasibly applied to large intestinal models. The use of distraction enterogenesis technology shows promise for application to clinical models in the treatment of pediatric intestinal disease.     

Intestinal adaptation following spring insertion into a roux limb in mice

Background/PurposeIntraluminal springs have recently been shown to lengthen segments of intestine in a process known as distraction enterogenesis. We hypothesized that biocompatible springs could be used to lengthen defunctionalized murine small intestine and would lead to identifiable intestinal adaptations at the molecular level.MethodsAge and weight matched C57BL/6 mice underwent surgical insertion of nitinol spring-loaded capsules into a Roux limb of jejunum. Segment lengths were measured at initial spring placement and at euthanasia after 14 and 21 days. Histology and gene expression of the Roux limb were evaluated at scarification and compared to untreated control segments.ResultsIntestinal segments loaded with compressed springs lengthened an average of 240%, which was significantly longer than control segments loaded with either empty capsules or uncompressed springs. Muscularis thickening was greater in spring-treated mice compared to controls without springs. Crypt depth and Lgr5 + expression was greater in mice that received compressed spring treatments when compared to control groups.ConclusionsInsertion of a compressed nitinol spring into a Roux limb results in significant intestinal lengthening, smooth muscle thickening, and Lgr5 + expression in a mouse model. The ability to increase small bowel length in a defunctionalized murine model may be used to understand the mechanism of distraction enterogenesis.     

Mesenteric neovascularization during spring-mediated intestinal lengthening

BackgroundShort gut syndrome, a condition characterized by inadequate absorption of nutrients owing to decreased bowel length, has minimal avenues for treatment. We have proposed spring-mediated distraction enterogenesis to lengthen bowel in porcine jejunum as a treatment for short gut. We aim to evaluate the extent of mesenteric neovascularization in segments of lengthened bowel via spring-mediated enterogenesis.MethodsFemale juvenile Yucatan pigs underwent laparotomy and insertion of gelatin-encapsulated compressed nitinol springs, held in place with plication sutures, into the jejunum. At surgery and sacrifice, macroscopic mesenteric blood vessels were counted between the plication sites. Histologic samples of the mesentery were obtained to evaluate microscopic vasculature.ResultsA statistically significant increase in macroscopic mesenteric blood vessels was seen after intestinal lengthening (before: 1.9 ± 0.7 vessels, after: 4.7 ± 1.2 vessels, p = 0.001). A statistical significance is also seen in the density of arterioles (control: 3.0 ± 3.0 vessels/mm, spring: 7.0 ± 9.0 vessels/mm, p = 0.01) and venules (control: 4.0 ± 3.0 vessels/mm, spring: 8.0 ± 8.0 vessels/mm, p = 0.003).ConclusionIntestinal segments lengthened by intraluminal springs demonstrated total greater number of macroscopic vessels and microscopic blood vessels per length of mesentery as compared to control. This suggests local changes within the mesentery to recruit blood supply to growing intestine.Level of evidenceN/AType of studyTreatment study.     

Double plication for spring-mediated in-continuity intestinal lengthening in a porcine model

Background

Short bowel syndrome is a condition with substantial morbidity and mortality, yet definitive therapies are lacking. Distraction enterogenesis uses mechanical force to “grow” new intestine. In this study, we examined whether intestinal plication can be used to safely achieve spring-mediated intestinal lengthening in a functioning segment of jejunum in its native position.

Double plication for spring-mediated intestinal lengthening of a defunctionalized Roux limb

Background

Spring-mediated distraction enterogenesis has been shown to increase the length of an intestinal segment. The goal of this study is to use suture plication to confine a spring within an intestinal segment while maintaining luminal patency to the rest of the intestine.

Long-term safety of intraluminal spring-mediated bowel lengthening

PurposeThe purpose of the study is to examine the long-term safety of an endoluminal bowel lengthening device prior to its use in the first human trial. In addition, device performance and natural passage will be evaluated.MethodsEndoluminal lengthening springs were surgically placed into the jejunum of Yucatan minipigs using the Eclipse XL1 device. A matching internal control segment of jejunum was marked at the time of operation. Weekly weights and fluoroscopic studies were obtained to evaluate spring deployment and position until devices passed. Animals were euthanized at 28, 60, 90, and 180 days. At necropsy, length measurements were recorded, and histopathologic analysis was performed.ResultsThere were no bowel obstructions or overt perforations attributable to the device. All surviving animals gained weight and were clinically thriving. All devices passed out of the rectum by 180 days. Bowel lengthening was seen in all experimental segments, and minimal fibrosis was observed by 180 days.ConclusionJejunal lengthening persisted after device had passed through the intestinal tract after 180 days. Early histopathologic changes of the jejunum during distraction enterogenesis normalized over time.     

The feasibility of using an endoluminal device for intestinal lengthening

Purpose

Prior studies demonstrating the ability to lengthen intestinal segments with mechanical force required devices with extracorporeal components. The feasibility of using a completely implantable device for in vivo intestinal lengthening was evaluated in this study.

Methods

Biocompatible Nitinol springs capable of 5-fold expansions were compressed using absorbable sutures and were implanted into isolated segments of proximal jejunum in rats. Springs compressed with nonabsorbable sutures served as controls. The animals were observed with serial abdominal x-rays until the springs became fully expanded. Intestinal segments were then retrieved for histologic analysis. Two-tailed and paired Student's t tests were used for statistical analysis.

Results

Intestinal segments were successfully lengthened in the experimental group from 1.3 ± 0.3 cm to 4.4 ± 0.5 cm (P < .001). Maximum spring length was achieved on postoperative day 36 (range, 16-50 days). In the control group, there was also an increase in intestinal lengths, from 1.6 ± 0.04 cm to 2.9 ± 0.4 cm (P < .001) (Fig. 4). In percentages, a 250% increase in length was observed in the experimental group vs an 85% increase in the control group (P < .001). Microscopic evaluation of both control and experimental segments revealed gross preservation of intestinal architecture; however, muscular layer hypertrophy and villous atrophy were noted.

Conclusions

Continuous mechanical force with an implantable spring successfully lengthened isolated segments of small bowel in an animal model. Although similar results have been demonstrated using other devices, the current device is totally implantable and may be deployed endoscopically.     

Development of an endoluminal intestinal lengthening capsule

PurposePrior studies demonstrated the ability of a spring to lengthen intestinal segments. We made two innovations to this device. First, we employed a degradable capsule to control the deployment of the spring. Second, we decreased the spring force to allow slower expansion of the intestinal segment.MethodsNitinol springs with varying forces were compressed and placed in gelatin capsules. These capsules were coated with a degradable polymer and were placed in isolated segments of rat jejunum. Serial x-rays were used to determine the rate of spring expansion. Retrieved jejunal segments were analyzed histologically.ResultsUsing the polymer-coated capsule, the spring was reliably deployed between 24 and 48 hours. Intestinal segments were lengthened from 1.0 cm to 3.6 cm after 14 days. The optimal spring for the gradual expansion of jejunal segments had a spring constant of 0.0010 N/mm. Villus height was preserved, but crypt depth was significantly greater in the lengthened intestine.ConclusionUse of a low-force spring resulted in a nearly four-fold lengthening of jejunal segments. The use of a polymer-coated capsule provided a reliable way to control the timing of spring deployment. This capsule may be useful for the endoscopic placement of the spring in patients with short bowel syndrome.     

Intestinal lengthening via multiple in-continuity springs

Background

Short bowel syndrome is a debilitating condition with few effective treatments. Spring-mediated distraction enterogenesis can be used to lengthen intestine. The purpose of this study is to determine whether multiple springs in series can safely increase the total amount of lengthening.

Intestinal lengthening in an innovative rodent surgical model

PurposeCurrent animal models of mechanical lengthening separate intestinal segments from enteric continuity. Such models are difficult to use for repeated lengthening procedures and result in intestinal tissue loss during restoration into continuity. We sought to create a novel surgical model to allow multiple lengthening procedures for the purpose of maximizing the net increase in tissue after intestinal lengthening.MethodsA Roux-en-y jejunojejunostomy with a 6-cm blind-ended Roux limb was created in the proximal jejunum of rats. Encapsulated 1-cm polycaprolactone springs were placed into the closed end of the roux limb and secured with a vessel loop. After 4 weeks, lengthened segments and normal jejunum were retrieved for histologic analysis.ResultsJejunal segments were lengthened from 1.0 cm to 3.0 cm. Lengthened segments had increased smooth muscle thickness, fewer submucosal ganglia, and similar numbers of myenteric ganglia compared to normal intestine. When compared to normal jejunal mucosa, lengthened segments demonstrated unchanged villus height and increased crypt depth.ConclusionsWe created an innovative surgical model for intestinal lengthening and successfully lengthened jejunal segments with a degradable spring. The Roux-en-y model may allow the use of a degradable spring for the treatment of short bowel syndrome.     

Restoration of mechanically lengthened jejunum into intestinal continuity in rats

PurposePrior studies demonstrated the feasibility of lengthening intestinal segments with mechanical force, but no previous studies have restored the lengthened segment back into intestinal continuity.MethodsA 1-cm segment of isolated rat jejunum was lengthened using a Nitinol spring. After lengthening, this segment was restored into intestinal continuity via a transection of the intact small intestine. Rats were euthanized 2 weeks later to retrieve the restored intestinal segment for histologic and enzymatic analyses.ResultsThe isolated jejunal segments were initially lengthened to 3.3 ± 0.9 cm. After the lengthened segments were restored into intestinal continuity for 2 weeks, the final length of the restored segment was 1.9 ± 0.7 cm. All rats continued to gain weight, and the intestine proximal to the restored jejunal segment remained normal 2 weeks later. The restored jejunal segment had an increase in crypt depth and no difference in villus height compared with normal jejunum. Sucrase activity in the restored segment was not different from that in normal jejunum.ConclusionMechanically lengthened jejunum can be restored into intestinal continuity and appears to have normal function. This further demonstrates the feasibility of mechanical enterogenesis as a potential therapy for short bowel syndrome.     

A novel biodegradable device for intestinal lengthening

Purpose

Previous studies demonstrated successful mechanical lengthening of rat jejunum using an encapsulated Nitinol spring device over a stabilizing guidewire. We sought to improve the applicability of intestinal lengthening by creating a biodegradable device.

Methods

Using properties of the Nitinol spring device, polycaprolactone (PCL) springs with similar outer diameter and spring constant were created. After in vitro testing in dry and hydrated environments, they were used to lengthen 1-cm isolated segments of rat jejunum in vivo. Retrieved segments were analyzed histologically.

Results

Optimal PCL spring devices had an average spring constant 1.8 ± 0.4 N/m, pitch 1.55 ± 0.85 mm, and band width 0.825 ± 0.016 mm. In vitro testing demonstrated stable spring constants. Jejunal segments were lengthened from 1.0 cm to 2.7 ± 0.4 cm without needing a stabilizing guidewire. Histology demonstrated increased smooth muscle thickness and fewer ganglia compared to controls. Lengthened jejunum was successfully restored into intestinal continuity and demonstrated peristalsis under fluoroscopy.

Conclusions

A novel biodegradable spring device was successfully created and used to mechanically lengthen intestinal segments. Use of a biodegradable device may obviate the need for retrieval after lengthening. This improves device applicability and may be useful for the treatment of short bowel syndrome.     

Clinical Significance of Plasma Tenascin-C Levels in Recipients With Prolonged Jaundice After Living Donor Liver Transplantation

BackgroundFocusing on tenascin-C (TNC), whose expression is enhanced during the tissue remodeling process, the present study aimed to clarify whether plasma TNC levels after living donor liver transplantation (LDLT) could be a predictor of irreversible liver damage in the recipients with prolonged jaundice (PJ).MethodsAmong 123 adult recipients who underwent LDLT between March 2002 and December 2016, the subjects were 79 recipients in whom we could measure plasma TNC levels preoperatively (pre-) and on postoperative days 1 to 14 (POD1 to POD14). Prolonged jaundice was defined as serum total bilirubin level >10 mg/dL on POD14, and 79 recipients were divided into 2 groups: 56 in the non-PJ (NJ) group and 23 in the PJ group.ResultsThe PJ group had significantly increased pre-TNC; smaller grafts; decreased platelet counts POD14; increased TB-POD1, -POD7, and -POD14; increased prothrombin time–international normalized ratio on POD7 and POD14; and higher 90-day mortality than the NJ group. As for the risk factors for 90-day mortality, multivariate analysis identified TNC-POD14 as a single significant independent prognostic factor (P = .015). The best cut-off value of TNC-POD14 for 90-day survival was determined to be 193.7 ng/mL. In the PJ group, the patients with low TNC-POD14 (<193.7 ng/mL) had satisfactory survival, with 100.0 % at 90 days, while the patients with high TNC-POD14 (≥193.7 ng/mL) had significantly poor survival, with 38.5 % at 90 days (P = .004).ConclusionsIn PJ after LDLT, plasma TNC-POD14 is very useful for diagnosing postoperative irreversible liver damage early.     

Function of mechanically lengthened jejunum after restoration into continuity

Purpose

Distraction enterogenesis is a potential treatment for patients with short bowel syndrome. We previously demonstrated successful lengthening of jejunum using a degradable spring device in rats. Absorptive function of the lengthened jejunum after restoration into intestinal continuity needs to be determined.

Methods

Encapsulated polycaprolactone springs were placed into isolated jejunal segments in rats for four weeks. Lengthened segments of jejunum were subsequently restored into intestinal continuity. Absorption studies were performed by placing a mixture of a non-absorbable substrate and glucose into the lumen of the restored jejunum.

Results

Restored jejunal segments demonstrated visible peristalsis at specimen retrieval. Compared to normal jejunal controls, restored segments demonstrated equal water absorption and greater glucose absorption. Restored segments had thicker smooth muscle, increased villus height, increased crypt depth, and decreased sucrase activity compared to normal jejunum. The density of enteric ganglia increased after restoration to near normal levels in the submucosa and to normal levels in the myenteric plexus.

Conclusion

Jejunum lengthened with a degradable device demonstrates peristaltic and enzymatic activity as well as glucose and water absorption after restoration into intestinal continuity. Our findings further demonstrate the therapeutic potential of a degradable device.     

Effect of bone morphogenic protein-2 and desferoxamine on distraction osteogenesis

BackgroundAngiogenesis is crucial for formation of a stable regenerate during distraction osteogenesis (DO). This experimental study evaluates if bone morphogenic protein-2 (BMP-2) and desferrioxamine (DFO), two agents which are known to induce neoangiogenesis in vivo, would increase angiogenesis and osteogenesis, and improve mechanical properties of bone regenerate in DO model.MethodsTwenty-four tibias of 24 New Zealand rabbits were osteotomized and fixed with semi-circular fixators. Three groups of 8 animals were formed. BMP-2 soaked scaffolds were used in the first group, whereas daily local DFO injections were made in the second group. Subjects in the control group did not receive any agents during the surgery or in the distraction period. The rabbits in all three groups underwent distraction at a rate of 0.6 mm/day for 15 days following the 7-day latent period. Animals were sacrificed on day 38, and the tibia were harvested for histological and mechanical examination of the regenerate.ResultsAll 24 rabbits survived the surgical procedure, and there were no side effects against the BMP-2 and local DFO. Three-point bending tests revealed a higher force (361 ± 267 N.) required for fracture in Group 1 (p: 0.018). Similarly, the bending moment in Group 1 (5.4 ± 4.0 Nmm) was significantly higher than the other groups (p: 0.021). There was no significant difference between the groups in terms of deflection and stiffness (p ? 0.05). Histologically, there was no statistical difference between the groups in terms of endochondral, periosteal, and intramembranous ossification and VEGF activity (p ? 0.05).ConclusionBMP-2 and DFO stimulate angiogenesis by increasing VEGF activity. Angiogenesis is one of the most important mechanisms for the initiation and maintenance of new bone formation. Stimulation of angiogenesis in unfavorable biomechanical conditions may not be sufficient for ideal bone formation.     

Patient-controlled analgesia (PCA) following video-assisted thoracoscopic lobectomy: Comparison of epidural PCA and intravenous PCA

ObjectivesTo compare the efficacy and side effects of epidural patient-controlled analgesia (EPCA) with those of intravenous patient-controlled analgesia (IVPCA) in fast-track video-assisted thoracoscopic (VATS) lobectomy.Patients and methodsEPCA or IVPCA was chosen by patients and was started immediately following tracheal extubation in the wake of completion of VATS lobectomy. EPCA analgesia was carried out with the PCA device programmed to deliver a bolus dose of 3 mL of 0.1% bupivacaine combined with 1.2 μg/mL fentanyl, and continuous epidural infusion at a rate of 4 mL/hour through an epidural catheter placed at the T_6-7 or T_7-8 level. IVPCA was made possible by a patient controlled infusion pump programmed to deliver 0.1% morphine with a loading dose of 3 mg, and the controlled bolus of 1 mg, at a lockout interval of 5 minutes. A rescue dose of 5 mg intravenous morphine was available for all patients in postoperative care unit. Pain management was assessed with visual analog scale at rest (VAS-R) and during motion (VAS-M); side effects including nausea, vomiting, pruritus, dizziness and sleepiness were recorded and analyzed from postoperative Day 1 (POD1) to Day 3 (POD3).ResultsThis study included 105 patients. Satisfactory pain control was achieved, although 9/70 patients in the EPCA group and 5/35 patients in the IVPCA group needed rescue morphine in the recovery room. The VAS-R was significantly higher on POD1 than on POD2 or POD3 in both groups (p < 0.001). The VAS-R and VAS-M were comparable in both groups on POD1 and POD3 but significant lower VAS-M was seen in the EPCA group on POD2 (p = 0.008). Higher incidence of dizziness was found in the IVPCA group on POD1 (p = 0.044) but the EPCA group had a higher incidence of pruritus on POD2 (p = 0.024) and POD3 (p = 0.03).ConclusionOur results indicated that the necessity of pain control was higher on POD1 for VATS lobectomy. Both EPCA and IVPCA can provide an adequate, continuous and effective means for postoperative pain management and a lower VAS-M was found in EPCA on POD2.     

Tacrolimus before CTLA4Ig and rapamycin promotes vascularized composite allograft survival in MGH miniature swine

BackgroundWe evaluated the outcome of vertical rectus abdominus myocutaneous flap (VRAM) allotransplantation in a mini-pig model, using a combined co-stimulation blockade (Co-SB) and mechanistic target of rapamycin inhibition (mTORi)-based regimen, with or without preceding calcineurin inhibition (CNI).Materials and methodsVRAM allotransplants were performed between SLA-mismatched MGH miniature swine. Group A (n = 2) was treated continuously with the mTOR inhibitor rapamycin from day −1 in combination with the Co-SB agent cytotoxic T lymphocyte antigen 4-Ig (CTLA4-Ig) from post-operative day (POD) 0. In group B (n = 3), animals received tacrolimus daily from POD 0 to POD 13, followed by rapamycin daily from POD 7 and CTLA4-Ig weekly from POD 7–28. Graft rejection was determined by Banff criteria and host cellular and humoral immunity monitored.ResultsIn group A, allografts developed grade-I acute rejection by POD 2 and POD 7, and reached grade-IV by POD 17 and POD 20, respectively. By contrast, in group B, two allografts demonstrated grade-I rejection on POD 30 and grade-IV on POD 74, while the third exhibited grade-I rejection starting on POD 50, though this animal had to be euthanized on POD 58 due to Pneumocystis jirovecii infection. Time-to-event incidence of grade-I rejection was significantly lower in group A compared to group B. During the first 3 weeks post-transplant, no significant differences in anti-donor immunity were observed between the groups.ConclusionA short course of CNI, followed by combined Co-SB and mTORi significantly delays acute rejection of VRAM allografts in SLA-mismatched miniature swine.     

Sustainability of mechanically lengthened bowel in rats

Introduction

It has been shown that the length of an intestinal segment may be doubled by applying gradual mechanical stretching. This study evaluated whether the lengthened intestinal segment retained the structure and function after the stretching device was removed.

Methods

A 1.5-cm jejunal segment was separated from intestinal continuity in 20 rats. After advancing a screw into the isolated jejunal segment by 5 mm 3 times a week until it was stretched by 3 cm, the screw was removed. Three weeks later, the jejunal segments were retrieved for analyses. Comparisons were made between the lengthened jejunal segments.

Results

The jejunal segment doubled its length after gradual stretching and retained this length 3 weeks after the screw removal (3.1 ± 0.8 vs 3.2 ± 0.4 cm, P > .05). The villous height, the muscular thickness, and the total alkaline phosphatase and lactase activities of the stretched jejunal segments were also unchanged 3 weeks after the screw removal.

Conclusions

Mechanical force induced the sustained lengthening of isolated jejunal segments in rats. The histologic and enzymatic alterations also persisted 3 weeks after the mechanical force was removed. This phenomenon may provide a novel method for the treatment of short bowel syndrome.     

Percutaneous cystostomy drainage for early removing urethral catheter in robotic-assisted laparoscopic radical prostatectomy: Improving on patients' discomfort

ObjectiveUrethral catheterization is often a major source of discomfort and pain to a patient after a surgical procedure. To better understand the safety and feasibility of the early removal of urethral Foley catheter after robotic-assisted laparoscopic radical prostatectomy by using percutaneous cystostomy drainage, we collected the related data and present our experience.Patients and methodsThis study involved 20 patients. In the study group (10 patients), we used the percutaneous cystostomy device (PCD) and an 18 French urethral catheter together. The urethral catheter was removed at postoperative day (POD) 3 and the PCD was removed at POD 7. In the control group (10 patients), they had standard urethral catheterization with an 18 French catheter and the catheter was removed at POD 7. Demographic and outcome data were measured and analyzed. Urethral pain was recorded using the visual analog scale.ResultsThe two groups were comparable in terms of age, serum prostate specific antigen level, body mass index, clinical tumor stage, surgical duration, estimated blood loss, and surgical times. The study group had significantly less penile pain in POD 3 and POD 7 (mean visual analog scale: 0.9 vs. 2.2, p < 0.001 at POD 3; 0.1 vs. 1.4, p = 0.002 at POD 7). All patients had good urinary continence within 30 days and no urethra stricture was found during the follow up period.ConclusionThe use of a percutaneous cystostomy device is feasible and safe for the early removal of urethral Foley catheter in robotic-assisted laparoscopic radical prostatectomy to decrease penile pain and patient discomfort.