Edgar J. Poth Memorial Lecture. Surgical aspects of the short-bowel syndrome

Influência de válvulas artificiais sobre a morfometria intestinal de ratos

OBJETIVO: Avaliar o papel de válvulas artificiais constituídas por seromiotomias circunferenciais duplas no comprimento dos vilos, no diâmetro do intestino delgado e no peso de ratos. MÉTODO: Foram utilizados 40 ratos, distribuídos em quatro grupos. Os animais do Grupo R foram submetidos à ressecção de 50% do intestino delgado, sem criação de válvulas. No Grupo RV associaram duas válvulas à ressecção intestinal. No Grupo V foram criadas duas válvulas, sem ressecção intestinal. O Grupo C forneceu a altura normal dos vilos. A eutanásia deu-se entre o décimo e o 14º dia pós-operatórios. RESULTADOS: Houve aumento no comprimento dos vilos nos grupos R, RV e V. Comparado ao Grupo R, o comprimento dos vilos nos grupos RV e V foi semelhante nos segmentos proximal e distal. No Grupo RV, os vilos do segmento proximal tiveram comprimento superior ao do distal. No Grupo V, o comprimento dos vilos do segmento proximal foi menor que do distal. A alça intestinal teve diâmetro maior que no pré-operatório no Grupo R e nos segmentos proximal à primeira válvula e distal à segunda, dos grupos RV e V. A ressecção intestinal levou à perda ponderal nos grupos R e RV, sem diferença entre os grupos. No Grupo V houve ganho de peso, significativo quando comparado aos grupos R e RV. Apesar de não impedirem a perda ponderal em animais submetidos à ressecção, as válvulas não determinaram perda superior à da ressecção isolada. CONCLUSÃO: Essas válvulas parecem influenciar positivamente a adaptação intestinal e podem ser incluídas entre as técnicas de reabilitação intestinal cirúrgica, isoladamente ou precedendo intervenções de alongamento do intestino.

Estudo morfológico do intestino de ratos após a criação cirúrgica de esfíncteres artificiais

OBJETIVO: Avaliar as alterações morfológicas ocorridas após à confecção de esfíncteres no intestino delgado de ratos. MÉTODO: Foram estudados 30 ratos, Wistar, distribuídos em três grupos de 10 animais. Grupo A, controle, foi retirado um segmento de intestino delgado de 20mm de extensão. Grupo B, foram realizados dois esfíncteres, um a 100mm e outro a 150mm da junção íleo-cecal. Grupo C, um esfíncter à 100mm da junção íleo-ceco-cólica. Entre 10º e 14º dia os animais do Grupo B e C foram re-operados para a ressecção do segmento intestinal envolvendo os esfíncteres com margem de 10mm proximal e distal. As aferições de peso foram feitas no pré-operatório das duas intervenções. O diâmetro das alças foi computado antes e depois da confecção dos esfíncteres. Nas peças ressecadas dos três grupos foram medidas as alturas das vilosidades dos segmentos pré e pós-esfíncter dos Grupos B e C, segmento intermediário do Grupo B e segmento intestinal do Grupo A. Os dados obtidos foram submetidos à análise estatística do programa SPSS. RESULTADO: O peso dos animais aumentou nos dois grupos com significância no grupo B. Aumento do diâmetro das alças e a média das alturas das vilosidades foram significante. CONCLUSÃO: A confecção dos esfíncteres leva a alterações da camada de vilos e dos diâmetros das alças, semelhantes àquelas que ocorrem na fase de adaptação intestinal após ressecções.

First report of the international serial transverse enteroplasty data registry: indications, efficacy, and complications

BACKGROUND

Serial transverse enteroplasty (STEP) is a novel surgical therapy for short bowel syndrome and is being used with increasing frequency worldwide. Because no single center is likely to obtain sufficient experience for meaningful analysis, we created the International STEP Data Registry to allow for larger, multicenter patient accrual and followup. This report describes patient characteristics, operative parameters, and early results of STEP in the first 38 patients enrolled in the International STEP Data Registry.

STUDY DESIGN

After IRB approval, data were entered online through password-protected enrollment and followup forms. Patient and procedural characteristics were analyzed. Pre- and postoperative small bowel length and enteral feeding tolerance were compared with the paired t-test.

RESULTS

Between September 1, 2004, and April 30, 2006, 19 centers from 3 countries enrolled 38 patients. Median followup from STEP procedure to analysis was 12.6 months (range 0 to 66.9 months). Indications for STEP were short bowel syndrome (SBS, n=29), bacterial overgrowth (n=6), and neonatal atresia (n=3). Mean small intestine length was substantially increased in all groups (68+/-44 cm versus 115+/-87 cm, p < 0.0001, n=27). Notable complications included intraoperative staple line leak (n=2), bowel obstruction (n=2), and fluid collection or abscess (n=3). Late outcomes included progression to transplantation (n=3) and mortality (n=3). For the short bowel syndrome cohort, enteral tolerance was notably increased from 31%+/-31% to 67%+/-37% of calories (p < 0.01, n=21).

CONCLUSIONS

STEP has been performed at multiple centers with minimal complications and encouraging outcomes. Indications for the procedure have broadened beyond short bowel syndrome to include bacterial overgrowth and neonatal intestinal obstruction with dilated proximal intestine. Continued accrual and followup of patients in the International STEP Data Registry will elucidate the longterm safety and efficacy of the procedure, with the goal of improved patient selection and operative timing.

[Effects of intrinsic denervation of the jejunum after extensive enterectomy in the rat bowel syndrome]

PURPOSE

To investigate the effects of intrinsic denervation of the jejunum after the extensive intestinal resection in rats.

METHODS

Thirty male Wistar rats were distributed into three groups, depending on the experimental procedure: Group C (control), Group R (resection) and Group D (resection plus denervation). The body weight gain and a histomorphometric study of the jejunal mucosa were performed.

RESULTS

The mean body weight of the group D animals showed a higher increase when compared to group R (D=312.2+/-21 g and R=196.7+/-36.2g). The number of jejunum myenteric neurons was smaller in group D (344.8+/-34.8 neurons/mm) when compared to other groups (R=909.0+/-55.5 and C=898.5+/-73.3). A hyperplasia of the jejunum mucosal epithelium was observed in the group D but also in the group R (R=7.3+/-3.9 mm2 and D=10.8+/-4.3 mm2), when compared to group C (C=5.8+/-3.0 mm2). The epithelial cell proliferation of the jejunum was higher in group D animals (48.7%) when compared to the other groups (R=31.9% and C=23.6%).

CONCLUSIONS

The denervated animals presented an increase the body weight gain and mucosal cell proliferation responses when compared to the control group. This experimental model may provide new strategies for the surgical treatment of the short bowel syndrome.

Late regeneration of infarcted small bowel mucosa: a case report

Ischemic injury of the small bowel may recover after revascularization, provided that full-thickness infarction did not occur. Animal studies showed that if the mucosal crypts remain viable, rapid mucosal restitution occurs hours after injury. The treatment of transmucosal infarction that does not extend to full wall thickness, however, was not investigated thoroughly. The patient presented had a mesenteric event leading to resection of about half of his small bowel. The unresected segment had severe ischemic injury, which seemed to cause transmucosal, but not transmural, infarction. Imaging of the remaining small bowel revealed a seromuscular layer denuded of mucosa. The ischemic damage was too deep to allow rapid regeneration, and the patient had short-bowel syndrome. A year later, during operation for stricture complications, new mucosa covered parts of the small-bowel surface, encouraging the surgeon to elect a conservative approach. Sixteen months after the injury, normal mucosa covered the entire small bowel, and enteral feeding resumed successfully. This report shows that infarcted small-bowel mucosa may regenerate even months after injury.

Adult small intestinal transplantation in England and Wales

BACKGROUND

In 1996 two transplantation centres in the UK were commissioned by the National Specialist Commissioning Advisory Group for England and Wales to assess small intestinal transplantation in adults. The joint experience of the two centres is presented.

METHODS

Patients with irreversible small intestinal failure and complications of parenteral nutrition, and those with abdominal disease requiring extensive visceral resection, were assessed as candidates and where appropriate listed for surgery.

RESULTS

Thirty-six patients were assessed for small intestinal transplantation and, of these, 14 underwent surgery. Twelve patients survived the transplantation procedure. Of these, seven patients were alive at 1 year, five at 3 years and three at 5 years. Three patients remain alive. Patient and graft survival improved with experience; the 1-year survival rate improved in the last 4 years of this experience from 43 to 57 per cent, and the 3-year survival rate from 29 to 43 per cent.

CONCLUSION

Small intestinal transplantation is associated with a high mortality rate but may benefit carefully selected patients in whom conservative management is likely to carry a greater mortality rate.

An integrated approach to intestinal failure: results of a new program with total parenteral nutrition, bowel rehabilitation, and transplantation

Intestinal failure can be treated with bowel rehabilitation, total parenteral nutrition, or intestinal transplantation. Little has been done to integrate these therapies for patients with intestinal insufficiency or failure and to develop an algorithm for appropriate use and timing. We established a multidisciplinary program using bowel rehabilitation, total parenteral nutrition, or intestinal transplantation as appropriate in a large population. Evaluation included clinical, pathologic, and psychosocial assessments and assignment to therapy based on the results of this evaluation. Of 59 patients evaluated for life-threatening complications of intestinal failure, 68% were considered appropriate candidates for transplantation, 10% were managed with rehabilitation, and 17% were maintained on optimized long-term parenteral nutrition. Nineteen transplants were performed, with 78% patient survival and 66% graft survival. Patient survival among isolated intestine recipients was 90%. All patients managed with rehabilitation were weaned from parenteral nutrition within 6 months. Long-term management with parenteral nutrition resulted in a significant number of deaths both among patients waiting for a transplant and those who were poor candidates for transplant. Intestinal rehabilitation, when successful, is optimal. For patients with irreversible intestinal failure, isolated intestinal transplantation holds particular promise. Parenteral nutrition is plagued by high failure rates among this population of debilitated patients compared with the general parenteral nutrition population. Integration of these therapies, with individualization of care based on a multidisciplinary approach and perhaps with earlier isolated intestinal transplantation for patients with irreversible intestinal failure, should optimize survival.

The surgical management of short bowel syndrome

Short bowel syndrome is a clinical entity that results from a diverse group of congenital and acquired conditions in the pediatric population. The pathophysiology of this syndrome is characterized by malabsorption, malnutrition, and metabolic disturbances. The vast majority of children with this condition undergo spontaneous adaptation of the intestinal remnant and achieve enteral nutritional autonomy. However, a small portion of pediatric patients develop intestinal failure and require long-term or permanent dependence on total parenteral nutrition. These children may benefit from surgical interventions that facilitate intestinal adaptation. Such adjunctive procedures facilitate nutrient absorption by improving motility, prolonging intestinal transit, and/or increasing mucosal contact time. In selected patients, this may allow them to be weaned from parenteral nutritional support or to have it discontinued. The purpose of this review is to discuss the various surgical techniques for the management of short bowel syndrome in children, along with their indications, complications, and outcomes.

SHORT BOWEL SYNDROME IN CHILDREN

Short bowel syndrome, a devastating outcome after major intestinal resection, manifests as malabsorption and diarrhoea. Improved outcome in recent years has come about with better understanding of the disease and its sequelae. Medical therapy using H2 receptor antagonists, loperamide and growth hormone analogues has been found useful. Total parenteral nutrition has revolutionized the outcome of this crippling disorder. Diverse spectrums of surgical procedures aimed at deceleration of intestinal transit and intestinal lengthening have not found favour in clinical practice. Intestinal transplantation remains the only viable option when intestinal adaptation is inadequate and complications of total parenteral nutrition ensue.

Interleukin-11 enhances small intestine absorptive function and mucosal mass after intestinal adaptation

BACKGROUND/PURPOSE

Interleukin-11 (IL-11) recently has been shown to enhance mucosal mass after massive small bowel resection (MSBR). However, enhanced mucosal mass may not correlate with increased substrate absorption. This study was designed to examine the effect of systemic administration of increasing doses of IL-11 on small intestine absorptive function and mucosal mass after MSBR.

METHODS

Twenty-five Sprague-Dawley rats underwent an 80% small bowel resection and end-to-end jejunoileal anastomosis. Seven days after resection, all rats had placement of a jugular venous catheter connected to a subcutaneously placed osmotic pump. The rats were divided into 5 groups based on the content of the pump: group 1 (control, n = 5) received 0.1% bovine serum albumin (BSA) and groups 2 through 5 (n = 5 each) received IL-11 at 250, 500, 750, and 1,000 microg/kg/d, respectively. After a 14-day infusion period, [14C] galactose and [14C] glycine absorption was measured using an in vivo closed-recirculation technique. Mucosal DNA content also was determined for each group. Statistical analysis was performed by analysis of variance and expressed as mean +/-SEM.

RESULTS

IL-11 administered at 250 microg/kg/d, a dose used in previous studies, did not significantly affect substrate absorption. However, compared with the control group, administration of higher doses of IL-11 produced a significant increase in substrate absorption and mucosal mass. The dose of IL-11 producing the overall optimal response based on the parameters measured (galactose absorption, 72% increase over control; glycine absorption, 112% increase over control; and DNA content, 98% increase over control) was 750 microg/kg/d.

CONCLUSIONS

In addition to an increase in mucosal mass, these data show for the first time that IL-11 enhances absorptive function beyond the normal adaptive response after MSBR. Furthermore, the maximum effect of IL-11 on absorptive function was shown at 750 microg/kg/d, which is 3 times the dose used in previously reported studies. This study suggests that IL-11 may be useful clinically in patients with inadequate intestinal function.

Effects of anastomosis of tissue-engineered neointestine to native small bowel

BACKGROUND

Our laboratory is investigating the tissue engineering of small intestine using intestinal epithelial organoid units seeded onto highly porous biodegradable polymer matrices. This study investigated the effects of anastomosis of tissue-engineered intestine to native small bowel alone or combined with small bowel resection on neointestinal regeneration.

METHODS

Intestinal epithelial organoid units harvested from neonatal Lewis rats were seeded onto biodegradable polymer tubes and implanted into the omentum of adult Lewis rats as follows: (1) implantation alone (n = 9); (2) implantation followed by anastomosis to native small bowel at 3 weeks (n = 11); and (3) implantation after small bowel resection and anastomosis to native small bowel at 3 weeks (n = 8). All constructs were harvested at 10 weeks and examined by histology. Morphometric analysis of the neomucosa was obtained using a computer image analysis program.

RESULTS

Cyst development was noted in all animals. All anastomoses were patent at 10 weeks. Histology revealed the development of a vascularized tissue with a neomucosa lining the lumen of the cyst with invaginations resembling crypt-villus structures. Morphometric analysis demonstrated significantly greater villus number, villus height, crypt number, crypt area, and mucosal surface length in groups 2 and 3 compared with group 1, and significantly greater villus number, villus height, crypt area, and mucosal surface length in group 3 compared with group 2 (P < 0.05, ANOVA, Tukey test).

CONCLUSION

Intestinal epithelial organoid units transplanted on biodegradable polymer tubes can regenerate into complex tissue resembling small intestine. Anastomosis to native small bowel combined with small bowel resection and anastomosis alone contribute significant regenerative stimuli for the morphogenesis and differentiation of tissue-engineered neointestine.

Regenerative signals for intestinal epithelial organoid units transplanted on biodegradable polymer scaffolds for tissue engineering of small intestine

BACKGROUND

Our laboratory is investigating the tissue engineering of small intestine using intestinal epithelial organoid units seeded onto highly porous biodegradable polymer tubes. This study investigated methods of stimulation for optimizing neointestinal regeneration.

METHODS

Intestinal epithelial organoid units harvested from neonatal Lewis rats were seeded onto porous biodegradable polymer tubes and implanted into the omentum of adult Lewis rats in the following groups: (1) the control group (group C), implantation alone (n=9); (2) the small bowel resection (SBr) group, after 75% SBr (n=9); (3) the portacaval shunt (PCS) group, after PCS (n=8); and (4) the partial hepatectomy (PH) group, after 75% PH (n=8). Neointestinal cyst size was recorded using ultrasonography. Constructs were harvested at 10 weeks and were examined using histology. Morphometric analysis of the neomucosa was obtained using a computer image analysis program (NIH Image, version 1.59).

RESULTS

Cyst development was noted in all animals. Cyst lengths and diameters were significantly larger in the SBr group at 7 and 10 weeks compared with the other three groups (P<0.05; analysis of variance [ANOVA], Fisher's protected least significant difference). Histology revealed a well-vascularized tissue with a neomucosa lining the lumen with invaginations resembling crypt-villus structures. Morphometric analysis demonstrated a significantly greater villus number, height, area, and mucosal surface in the SBr group compared with the other three groups and a significantly greater crypt number and area in the PCS group compared with group C (P<0.05; ANOVA, Fisher's protected least significant difference).

CONCLUSIONS

Intestinal epithelial organoid units transplanted on porous biodegradable polymer tubes can successfully vascularize, survive, and regenerate into complex tissue resembling small intestine. SBr and, to a lesser extent, PCS provide significant regenerative stimuli for the morphogenesis and differentiation of tissue-engineered small intestine.

The effects of surgery on gastrointestinal motor activity

Gastrointestinal surgical procedures have the potential to disrupt motor activity in various organs of the gastrointestinal tract or, indeed, throughout the entire alimentary canal. Several of these motor effects have important clinical consequences and have also served to advance our understanding of the regulation of gastrointestinal motor activity. This review will focus, in particular, on the effects of surgery on the small intestine, and will attempt to emphasize the implications of these studies for our understanding of small intestinal motility, in general.

Studies of brush border enzymes, basement membrane components, and electrophysiology of tissue-engineered neointestine

BACKGROUND/PURPOSE

Previous studies have shown that intestinal crypt cell transplantation using biodegradable scaffolds can generate stratified epithelium reminiscent of embryonic gut. The authors propose to tissue engineer small intestine on biodegradable scaffolds by transplanting intestinal epithelial organoid units, which maintain the epithelial mesenchymal cell-cell interaction necessary for epithelial survival, proliferation, and differentiation.

METHODS

Intestinal epithelial organoid units were isolated from neonatal Lewis rats by enzyme digestion and differential sedimentation. Organoid units were seeded on to tubular scaffolds made of nonwoven polyglycolic acid (PGA) sprayed with 5% polylactic acid (PLA). Polymers either were coated (28 constructs) or noncoated (33 constructs) with collagen type I. A total of 61 organoid unit polymer constructs were implanted into 61 animals. Animals were killed and constructs harvested at 2, 6, 7, 8, 9, 10, 12, and 14 weeks.

RESULTS

Histological analysis showed formation of neomucosa characterized by columnar epithelium with goblet, and paneth cells were evident in 47 of the 61 constructs. The outer walls were composed of fibrovascular tissue, degradable polymer, extracellular matrix, and smooth muscle-like cells. Immunofluorescent microscopy showed apical staining of brush border enzymes, sucrase and lactase, and basolateral staining for laminin, indicating the establishment of cell polarity. Electrophysiology of Ussing-chambered neomucosa and adult ileal mucosa exhibited similar transepithelial resistance.

CONCLUSION

These results suggest that intestinal crypt cells heterotopically transplanted as epithelial organoid units on PGA-PLA tubular scaffolds can survive, reorganize, and regenerate complex composite tissue resembling small intestine demonstrating organ morphogenesis, cytodifferentiation, and phenotypic maturation.