- Email: [email protected]
Staging of the axilla using ultrasound guidance in locally advanced breast cancers
of gastric and esophageal injury, it may provide low rates of postoperative dysphagia and reflux recurrence. 8 Laparoscopic management of anastomotic leak: a novel approach Braveman JM, Marcello P, Schoetz D. From the Lahey Clinic, Burlington, Massachusetts. Purpose: The traditional approach to anastomotic leakage with intra-abdominal sepsis after colorectal surgery requires exploratory laparotomy, control of contamination, and proximal diversion. With increasing experience in laparoscopic intestinal surgery, we have recently managed this complication laparoscopically, defying the classic approach. Methods: Review of a prospective registry identified 4 patients requiring emergent laparoscopic surgery for anastomotic/staple line leakage. Results: A 70-year-old man (#1) with leakage after low anterior resection for rectal cancer was managed by a loop ileostomy and pelvic drainage. A 47-yearold woman (#2) developed a leak after laparoscopic total colectomy with ileorectal anastomosis, requiring suture repair of leakage, washout, and drainage. A 73-year-old woman (#3) developed a small anastomotic leak and abscess after a sigmoid resection for diverticulitis. The abscess was not amenable to percutaneous drainage and was treated by laparoscopic drainage. A 28-year-old man (#4) developed a Hartmann stump leak after a laparoscopic total colectomy and ileostomy for acute colitis, requiring washout and drainage. All leaks subsequently sealed postoperatively without the need for further intervention. Conclusions: A laparoscopic approach to anastomotic complications is safe and feasible after both conventional and laparoscopic colorectal surgery. 9 Measuring service-specific performance and educational value within a general surgery residence Antonetti M, Kirton OC, Morejon O, Horowitz S, Civetta JM. From the Department of Surgery, University of Connecticut Health Center and School of Medicine, Farmington, Connecticut. Purpose: We instituted specific changes to various clinical teaching services in our integrated residency in an effort to optimize the overall quality of the educational experience, and we measured the resident satisfaction in these rotations using a Web-based evaluation system. Methods: Residents rated 8 categories of experience on a scale of 1 to 5 (maximum summation score ⫽ 40). Data were analyzed by t-test for equality of means. A p-value less than 0.05 was considered significant. Results: Compliance with completion of evaluations was 100%. The Chronbach’s alpha reliability coefficient of the tool was 0.826. Tukey’s estimate of power to achieve additivity was 1.5. Six underperforming services were reengineered with prominent effects on 7 postgraduate year (PGY) rotations. On 2 General Surgery services at 1 hospital, the workload was redistributed and dedicated team teaching time instituted; [PGY-3 (a) pre 22/post 31, p ⫽ 0.003; PGY-3 (b) pre 25/post 31, p ⫽ 0.004; and a PGY-1 pre 24/post 29, p ⫽ 0.07]. A general surgery service at another hospital had redistribution of attending coverage to create a nonteaching service (PGY-1 pre 22/post 27, p ⫽ 0.01). The transplant service (PGY-3) was examined, and the role of the resident was redefined (pre 24/post 31 p ⫽ 0.01). One Vascular service (PGY-2) had redistribution of cases and workload (pre 27/post 22, p ⫽ 0.07). The vascular PGY-2 position was eliminated and replaced by a midlevel practitioner. The Cardiothoracic service (PGY-1) rotation was converted into a preceptorship (pre 23/post 30, p ⫽ 0.015). Conclusions: A Web-based clinical rotation evaluation provides a means of assessing the impact of programmatic changes while preserving resident anonymity and maintaining accountability. 10 Poly-N-Acetyl Glucosamine as a topical hemostatic agent in an animal hemorrhage model Arnold W, Schwaitzberg SD, Finkielsztein S, Vournakis J, Connolly RJ. From the New England Medical Center, Boston, Massachusetts.
Purpose: To establish the hemostatic effectiveness of Poly-N-Acetyl Glucosamine (P-GlcNAc) in multiple models of animal hemorrhage. To test the hemostatic properties of P-GlcNAc under conditions of coagulopathy. To compare the hemostatic capabilities of P-GlcNAc to other topical hemostatic agents. Methods: We compared standard gauze compression to compression with a patch of P-GlcNAc on a swine model of lower extremity trauma. Hemostatic efficiency was judged by measuring blood loss using Tc99m-labeled red blood cells and the number of 1-minute compressions required to achieve hemostasis. We compared the hemostatic potential of topically applied P-GlcNAc to other topically applied hemostatic agents (fibrin sealant, Actifoam, Surgicel) in a swine model of splenic hemorrhage under heparinized and unheparinized conditions. Again, hemostatic effiency was judged by the number of compressions required to achieve hemostasis. We also evaluated the hemostatic properties of P-GlcNAc under normothermic and hypothermic conditions in a rabbit aortic injury model. In this series of experiments, the P-GlcNAc was applied to a standardized aortic laceration under normothermic conditions and after lowering body temperature to 29 °C. Samples of the lacerated splenic tissue with the topically applied P-GlcNAc and samples with topically applied fibrin glue were examined for histopathology. Similar samples were evaluated for distribution of the vasoactive substance, Endothelin 1, by immunohistochemical staining. Results: In the swine model of splenic hemorrhage, P-GlcNAc achieved hemostasis in 23 seconds compared with fibrin glue, which required an average of 170 seconds. Further, P-GlcNAc was 79% effective in achieving hemostasis with 1 application to the lacerated spleen compared with 17% effectiveness for both Surgicel and Actifoam. Under conditions of heparinization, the P-GlcNAc achieved hemostasis for splenic lacerations 72% of the time with 1 application compared with 0% effectiveness for Actifoam with 1 application. In the controlled surgical trial of swine extremity trauma, gauze compression yielded an average blood loss of 35% total blood volume compared with 13% blood loss with P-GlcNAc compression. P-GlcNAc required 4.6 ⫾ 2.6 compressions to arrest bleeding from the injured extremity compared with 13.8 ⫾ 2.7 and 13.2 ⫾ 3.0 compressions with gauze and Tachacomb, respectively. In the rabbit hypothermia model, no difference existed in P-GlcNAc’s hemostatic effectiveness when compared with normothermic controls. Immunostaining for Endothelin 1 demonstrated increased local concentration of this vasoactive polypeptide in the region of topically applied P-GlcNAc compared with topically applied fibrin glue. Conclusions: Poly-N-Acetyl Glucosamine is an effective topical hemostatic agent. P-GlcNAc compares favorably to other topical hemostatic agents tested. Its effectiveness persists under conditions of coagulopathy. P-GlcNAc’s precise mechanism of promoting local hemostasis has yet to be determined, but our results suggest that it may influence the local concentration of the powerful vasoconstrictor, Endothelin-1. 11 Staging of the axilla using ultrasound guidance in locally advanced breast cancers Oruwari JN,* Chung MA,* Koelliker S,† Steinhoff M,‡ Cady B.* From the Departments of *Surgery, †Radiology, and ‡Pathology, The Breast Health Center, Women and Infants Hospital of Rhode Island, Brown University School of Medicine, Providence, Rhode Island. Purpose: Ultrasound coupled with fine-needle aspiration biopsy (FNAB) of suspicious lymph nodes is superior to clinical examination alone for axillary staging in patients with locally advanced breast cancer (LABC) and clinically negative axillary examination. Methods: Twenty-six patients presented with LABC between January 1998 and March 2001. Eighteen patients (19 axillae) who had completed surgical treatment formed the basis for this study. Locally advanced breast cancer defined as a T2 cancer is greater than 3 cm. Patients were evaluated by clinical examination, and the axilla were evaluated by ultrasound-guided FNAB. Twelve patients (13 axillae) meeting the criteria for neoadjuvant chemotherapy (NAC) were started on chemotherapy, followed by breast conservation or mastectomy and axillary lymph node dissection (ALND). Six patients proceeded
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directly to surgery, which included ALND. Axillary nodal status after surgery was compared with preoperative status. Setting: A multidisciplinary breast center. Patients or Other Participants: Eighteen patients (median age, 46 years; range, 31 to 77 years) with LABC. Interventions: Ultrasound-guided FNAB of suspicious lymph nodes followed by ALND. Main Outcome Measures: Clinical examination of the axilla, ultrasoundguided FNAB, and final pathology of ALND were compared. Results: Axillary Examination
Number
US/FNAB (ⴙ)
US/FNAB (ⴚ)
ALND (ⴙ)
ALND (ⴚ)
Clinical (⫹) Clinical (⫺)
13 6
11 5
2 1
13 5
0 1
Conclusions: In patients with LABC, axillary ultrasound, followed by FNAB of suspicious nodes can accurately stage the axilla. This is particularly useful for patients with clinically negative axillae for whom NAC is a consideration. 12 The Nuss procedure: initial results with 27 patients Tashjian DB, Moriarty KP, Banever G, Konefal SH Jr. From the Division of Pediatric Surgery, Baystate Medical Center Children’s Hospital and Shriners Children’s Hospital, Tufts University School of Medicine, Springfield, Massachusetts. Purpose: The “gold standard” repair for pectus excavatum is the technique originally described by Ravitch. The Nuss procedure, a minimally invasive pectus excavatum repair without cartilage resection or sternal osteomy, was first described in 42 patients in 1998. This technique has gained rapid acceptance. We present our results from the initial 27 patients undergoing the minimally invasive Nuss pectus repair. Methods: A retrospective review of patients undergoing the Nuss procedure from April 1998 until the present was performed. Data concerning age, sex, clinical symptoms, computed tomography scan evaluation, operative time, length of hospital stay, and complications were recorded. Results from patients whose bar has been removed were also retrieved. Results: Twenty-seven patients, 21 males and 6 females, underwent the Nuss procedure. The average age of the patients was 12.4 years, with a range of 4 to 18 years. Preoperative symptoms included asthma, exercise intolerance, chest pain, or no symptoms. Average operative time was 86.7 minutes. Blood loss was minimal in each case. The average length of hospital stay was 6 days. Six immediate postoperative pneumothoracies occurred, none requiring a thoracostomy tube. Two bars became displaced. One occurred at 1 month, which was replaced, and the other at 15 months, which was removed. Only 1 patient had infection necessitating bar removal. Two bar stabilizers needed to be replaced. A total of 5 bars have been removed, all with excellent patient satisfaction. Conclusions: Compared with the open repair, the Nuss procedure offers decreased operative times, minimal blood loss, and improved cosmesis. Patient satisfaction is excellent. Long-term follow-up is needed. Based on short-term results, the minimally invasive Nuss procedure is a safe and effective alternative to the open pectus repair. 13 Tissue-engineered colon: characterization and comparison to native colon Grikscheit TC,* Ochoa ER,† Ramsanahie A,‡ Whang EE,‡ Vacanti JP.* From the Departments of *Surgery and †Pathology, Massachusetts General Hospital, and the ‡Department of Surgery, Brigham and Women’s Hospital. Boston, Massachusetts. Purpose: Postcolectomy morbidity rates from 5% to 30% have been reported. We created a tissue-engineered colon (TEC) substitute for surgical therapy using biodegradable polymer constructs to transplant multicellular sigmoid organoid units (OU). Characterization of TEC reveals significant similarity to 560
native colon (NC). For the first time, engineered intestine was constructed from adult rats and TEC. Methods: Organoid units were harvested from 6-day-old Lewis rats by excision, dissociation, differential centrifugation, and enzyme digestion, then seeded on 2-mm nonwoven polyglycolic acid/polylactic acid porous felt 1-cm ⫻ 0.5-cm tubular constructs, and implanted in 20 male Lewis rat omentums. At 4 weeks, 10 rats underwent ileo-colic or colo-colic anastomosis. Histology on TEC and anastomosed TEC included PAS, trichrome, and anti¨ ssing acetylcholinesterase (ACh). TEM and TUNEL assay were performed. U chamber studies assessed epithelial transport. Organoid units from 4-monthold adult Lewis rats were likewise implanted and studied. Results: All rats generated TEC at 4 weeks with uniform colonic epithelium, crypts of Lieberkuhn, and goblet cells. An outer longitudinal layer resembled a smooth muscle. After anastomosis, colon morphology was preserved for the study’s length, 6 weeks. As in NC, ACh stained the lamina propria; PAS stain revealed typical goblet cells, and Trichrome staining revealed a blue collagenrich submucosa. TEM revealed an exact repetition of NC architecture, including tight junctions, desmosomes with keratin filaments, neuroendocrine cells, and apical microvilli with anchoring filaments. TUNEL assays were equivalent ¨ ssing chamber studies exhibited a spontaneous short-circuit in NC and TEC. U current, suggesting active ion transport, and no short-circuit current response to 3-O-methylglucose addition, suggesting absence of epithelial SGLT1 expression, consistent with the presence of mature colonocytes. Positive short-circuit current response to theophylline suggests intact secretagogue-induced chloride secretion and tissue viability. Conclusions: A tissue-engineered colon is similar to NC by histology and preliminary functional assessment. This is the first report of engineered tissue derived from engineered tissue or adult intestine. Colon morphology in anastomosis confirms the source of TEC. A tissue-engineered colon may help provide a replacement function for postcolectomy patients in the future. 14 Tissue-engineered small intestine: ontogeny of the immune system Perez A,* Blumberg RS,† Grikscheit TC,‡ Ashley SW,* Vacanti JP,‡ Whang EE.* From the *Department of Surgery and †Division of Gastroenterology, Brigham and Women’s Hospital, and the ‡Department of Surgery, Massachusetts General Hospital. Boston, Massachusetts. Purpose: We have tissue-engineered neointestine that regenerates structural and transporter properties of native jejunum. Before our neointestine can undergo clinical application, mucosal immune function would need to be demonstrated. We hypothesized that the neointestinal mucosa is capable of developing a mature immune system and that exposure to luminal antigenic stimuli is critical to this development. Methods: Neointestinal cysts were engineered by implanting polymer-organoid constructs into adult rats. Neointestine (NA: cysts left nonanastomosed, n ⫽ 6 and AN: cysts anastomosed to native bowel, n ⫽ 4) and native jejunum were harvested serially (3 to 56 weeks postoperatively). Immune cell subsets were characterized by immunohistochemical detection of cell-specific antigens [T cells (CD 3), B cells (CD 32), NK cells (CD 56), and macrophages (CD 68)] combined with computer-based morphometry. Results: Neomucosal immune cell population was a function of exposure to luminal antigens and time of harvest. In AN mucosa harvested at 20 weeks, the density and topographical distribution of immune cell subsets was identical to that of normal jejunum. Table. Mucosal Immune Cell Density (cells/m2, mean ⴞ S.D.) CD
NA (20 weeks)
AN (10 weeks)
AN (20 weeks)
CD 3 CD 32
0.7 ⫻ 104 ⫾ 0.8 ⫻ 104* 0*
CD 56
0*
0.9 ⫻ 104 ⫾ 0.2 ⫻ 104** 0.2 ⫻ 104 ⫾ 0.1 ⫻ 104** 0**
CD 68
0*
0**
1.7 ⫻ 104 ⫾ 0.5 ⫻ 104 1.5 ⫻ 104 ⫾ 0.5 ⫻ 104 1.0 ⫻ 104 ⫾ 0.3 ⫻ 104 0.2 ⫻ 104 ⫾ 0.1 ⫻ 104
Jejunum 1.1 ⫻ 104 ⫾ 0.6 ⫻ 104 1.3 ⫻ 104 ⫾ 0.3 ⫻ 104 0.7 ⫻ 104 ⫾ 0.1 ⫻ 104 0.3 ⫻ 104 ⫾ 0.1 ⫻ 104
* p ⬍ 0.05 vs AN20 and Jej, ** p ⬍ 0.05 vs AN20. ANOVA with Tukey HSD.
CURRENT SURGERY • Volume 58/Number 6 • November/December 2001
Purpose: To establish the hemostatic effectiveness of Poly-N-Acetyl Glucosamine (P-GlcNAc) in multiple models of animal hemorrhage. To test the hemostatic properties of P-GlcNAc under conditions of coagulopathy. To compare the hemostatic capabilities of P-GlcNAc to other topical hemostatic agents. Methods: We compared standard gauze compression to compression with a patch of P-GlcNAc on a swine model of lower extremity trauma. Hemostatic efficiency was judged by measuring blood loss using Tc99m-labeled red blood cells and the number of 1-minute compressions required to achieve hemostasis. We compared the hemostatic potential of topically applied P-GlcNAc to other topically applied hemostatic agents (fibrin sealant, Actifoam, Surgicel) in a swine model of splenic hemorrhage under heparinized and unheparinized conditions. Again, hemostatic effiency was judged by the number of compressions required to achieve hemostasis. We also evaluated the hemostatic properties of P-GlcNAc under normothermic and hypothermic conditions in a rabbit aortic injury model. In this series of experiments, the P-GlcNAc was applied to a standardized aortic laceration under normothermic conditions and after lowering body temperature to 29 °C. Samples of the lacerated splenic tissue with the topically applied P-GlcNAc and samples with topically applied fibrin glue were examined for histopathology. Similar samples were evaluated for distribution of the vasoactive substance, Endothelin 1, by immunohistochemical staining. Results: In the swine model of splenic hemorrhage, P-GlcNAc achieved hemostasis in 23 seconds compared with fibrin glue, which required an average of 170 seconds. Further, P-GlcNAc was 79% effective in achieving hemostasis with 1 application to the lacerated spleen compared with 17% effectiveness for both Surgicel and Actifoam. Under conditions of heparinization, the P-GlcNAc achieved hemostasis for splenic lacerations 72% of the time with 1 application compared with 0% effectiveness for Actifoam with 1 application. In the controlled surgical trial of swine extremity trauma, gauze compression yielded an average blood loss of 35% total blood volume compared with 13% blood loss with P-GlcNAc compression. P-GlcNAc required 4.6 ⫾ 2.6 compressions to arrest bleeding from the injured extremity compared with 13.8 ⫾ 2.7 and 13.2 ⫾ 3.0 compressions with gauze and Tachacomb, respectively. In the rabbit hypothermia model, no difference existed in P-GlcNAc’s hemostatic effectiveness when compared with normothermic controls. Immunostaining for Endothelin 1 demonstrated increased local concentration of this vasoactive polypeptide in the region of topically applied P-GlcNAc compared with topically applied fibrin glue. Conclusions: Poly-N-Acetyl Glucosamine is an effective topical hemostatic agent. P-GlcNAc compares favorably to other topical hemostatic agents tested. Its effectiveness persists under conditions of coagulopathy. P-GlcNAc’s precise mechanism of promoting local hemostasis has yet to be determined, but our results suggest that it may influence the local concentration of the powerful vasoconstrictor, Endothelin-1. 11 Staging of the axilla using ultrasound guidance in locally advanced breast cancers Oruwari JN,* Chung MA,* Koelliker S,† Steinhoff M,‡ Cady B.* From the Departments of *Surgery, †Radiology, and ‡Pathology, The Breast Health Center, Women and Infants Hospital of Rhode Island, Brown University School of Medicine, Providence, Rhode Island. Purpose: Ultrasound coupled with fine-needle aspiration biopsy (FNAB) of suspicious lymph nodes is superior to clinical examination alone for axillary staging in patients with locally advanced breast cancer (LABC) and clinically negative axillary examination. Methods: Twenty-six patients presented with LABC between January 1998 and March 2001. Eighteen patients (19 axillae) who had completed surgical treatment formed the basis for this study. Locally advanced breast cancer defined as a T2 cancer is greater than 3 cm. Patients were evaluated by clinical examination, and the axilla were evaluated by ultrasound-guided FNAB. Twelve patients (13 axillae) meeting the criteria for neoadjuvant chemotherapy (NAC) were started on chemotherapy, followed by breast conservation or mastectomy and axillary lymph node dissection (ALND). Six patients proceeded
CURRENT SURGERY • Volume 58/Number 6 • November/December 2001
559
directly to surgery, which included ALND. Axillary nodal status after surgery was compared with preoperative status. Setting: A multidisciplinary breast center. Patients or Other Participants: Eighteen patients (median age, 46 years; range, 31 to 77 years) with LABC. Interventions: Ultrasound-guided FNAB of suspicious lymph nodes followed by ALND. Main Outcome Measures: Clinical examination of the axilla, ultrasoundguided FNAB, and final pathology of ALND were compared. Results: Axillary Examination
Number
US/FNAB (ⴙ)
US/FNAB (ⴚ)
ALND (ⴙ)
ALND (ⴚ)
Clinical (⫹) Clinical (⫺)
13 6
11 5
2 1
13 5
0 1
Conclusions: In patients with LABC, axillary ultrasound, followed by FNAB of suspicious nodes can accurately stage the axilla. This is particularly useful for patients with clinically negative axillae for whom NAC is a consideration. 12 The Nuss procedure: initial results with 27 patients Tashjian DB, Moriarty KP, Banever G, Konefal SH Jr. From the Division of Pediatric Surgery, Baystate Medical Center Children’s Hospital and Shriners Children’s Hospital, Tufts University School of Medicine, Springfield, Massachusetts. Purpose: The “gold standard” repair for pectus excavatum is the technique originally described by Ravitch. The Nuss procedure, a minimally invasive pectus excavatum repair without cartilage resection or sternal osteomy, was first described in 42 patients in 1998. This technique has gained rapid acceptance. We present our results from the initial 27 patients undergoing the minimally invasive Nuss pectus repair. Methods: A retrospective review of patients undergoing the Nuss procedure from April 1998 until the present was performed. Data concerning age, sex, clinical symptoms, computed tomography scan evaluation, operative time, length of hospital stay, and complications were recorded. Results from patients whose bar has been removed were also retrieved. Results: Twenty-seven patients, 21 males and 6 females, underwent the Nuss procedure. The average age of the patients was 12.4 years, with a range of 4 to 18 years. Preoperative symptoms included asthma, exercise intolerance, chest pain, or no symptoms. Average operative time was 86.7 minutes. Blood loss was minimal in each case. The average length of hospital stay was 6 days. Six immediate postoperative pneumothoracies occurred, none requiring a thoracostomy tube. Two bars became displaced. One occurred at 1 month, which was replaced, and the other at 15 months, which was removed. Only 1 patient had infection necessitating bar removal. Two bar stabilizers needed to be replaced. A total of 5 bars have been removed, all with excellent patient satisfaction. Conclusions: Compared with the open repair, the Nuss procedure offers decreased operative times, minimal blood loss, and improved cosmesis. Patient satisfaction is excellent. Long-term follow-up is needed. Based on short-term results, the minimally invasive Nuss procedure is a safe and effective alternative to the open pectus repair. 13 Tissue-engineered colon: characterization and comparison to native colon Grikscheit TC,* Ochoa ER,† Ramsanahie A,‡ Whang EE,‡ Vacanti JP.* From the Departments of *Surgery and †Pathology, Massachusetts General Hospital, and the ‡Department of Surgery, Brigham and Women’s Hospital. Boston, Massachusetts. Purpose: Postcolectomy morbidity rates from 5% to 30% have been reported. We created a tissue-engineered colon (TEC) substitute for surgical therapy using biodegradable polymer constructs to transplant multicellular sigmoid organoid units (OU). Characterization of TEC reveals significant similarity to 560
native colon (NC). For the first time, engineered intestine was constructed from adult rats and TEC. Methods: Organoid units were harvested from 6-day-old Lewis rats by excision, dissociation, differential centrifugation, and enzyme digestion, then seeded on 2-mm nonwoven polyglycolic acid/polylactic acid porous felt 1-cm ⫻ 0.5-cm tubular constructs, and implanted in 20 male Lewis rat omentums. At 4 weeks, 10 rats underwent ileo-colic or colo-colic anastomosis. Histology on TEC and anastomosed TEC included PAS, trichrome, and anti¨ ssing acetylcholinesterase (ACh). TEM and TUNEL assay were performed. U chamber studies assessed epithelial transport. Organoid units from 4-monthold adult Lewis rats were likewise implanted and studied. Results: All rats generated TEC at 4 weeks with uniform colonic epithelium, crypts of Lieberkuhn, and goblet cells. An outer longitudinal layer resembled a smooth muscle. After anastomosis, colon morphology was preserved for the study’s length, 6 weeks. As in NC, ACh stained the lamina propria; PAS stain revealed typical goblet cells, and Trichrome staining revealed a blue collagenrich submucosa. TEM revealed an exact repetition of NC architecture, including tight junctions, desmosomes with keratin filaments, neuroendocrine cells, and apical microvilli with anchoring filaments. TUNEL assays were equivalent ¨ ssing chamber studies exhibited a spontaneous short-circuit in NC and TEC. U current, suggesting active ion transport, and no short-circuit current response to 3-O-methylglucose addition, suggesting absence of epithelial SGLT1 expression, consistent with the presence of mature colonocytes. Positive short-circuit current response to theophylline suggests intact secretagogue-induced chloride secretion and tissue viability. Conclusions: A tissue-engineered colon is similar to NC by histology and preliminary functional assessment. This is the first report of engineered tissue derived from engineered tissue or adult intestine. Colon morphology in anastomosis confirms the source of TEC. A tissue-engineered colon may help provide a replacement function for postcolectomy patients in the future. 14 Tissue-engineered small intestine: ontogeny of the immune system Perez A,* Blumberg RS,† Grikscheit TC,‡ Ashley SW,* Vacanti JP,‡ Whang EE.* From the *Department of Surgery and †Division of Gastroenterology, Brigham and Women’s Hospital, and the ‡Department of Surgery, Massachusetts General Hospital. Boston, Massachusetts. Purpose: We have tissue-engineered neointestine that regenerates structural and transporter properties of native jejunum. Before our neointestine can undergo clinical application, mucosal immune function would need to be demonstrated. We hypothesized that the neointestinal mucosa is capable of developing a mature immune system and that exposure to luminal antigenic stimuli is critical to this development. Methods: Neointestinal cysts were engineered by implanting polymer-organoid constructs into adult rats. Neointestine (NA: cysts left nonanastomosed, n ⫽ 6 and AN: cysts anastomosed to native bowel, n ⫽ 4) and native jejunum were harvested serially (3 to 56 weeks postoperatively). Immune cell subsets were characterized by immunohistochemical detection of cell-specific antigens [T cells (CD 3), B cells (CD 32), NK cells (CD 56), and macrophages (CD 68)] combined with computer-based morphometry. Results: Neomucosal immune cell population was a function of exposure to luminal antigens and time of harvest. In AN mucosa harvested at 20 weeks, the density and topographical distribution of immune cell subsets was identical to that of normal jejunum. Table. Mucosal Immune Cell Density (cells/m2, mean ⴞ S.D.) CD
NA (20 weeks)
AN (10 weeks)
AN (20 weeks)
CD 3 CD 32
0.7 ⫻ 104 ⫾ 0.8 ⫻ 104* 0*
CD 56
0*
0.9 ⫻ 104 ⫾ 0.2 ⫻ 104** 0.2 ⫻ 104 ⫾ 0.1 ⫻ 104** 0**
CD 68
0*
0**
1.7 ⫻ 104 ⫾ 0.5 ⫻ 104 1.5 ⫻ 104 ⫾ 0.5 ⫻ 104 1.0 ⫻ 104 ⫾ 0.3 ⫻ 104 0.2 ⫻ 104 ⫾ 0.1 ⫻ 104
Jejunum 1.1 ⫻ 104 ⫾ 0.6 ⫻ 104 1.3 ⫻ 104 ⫾ 0.3 ⫻ 104 0.7 ⫻ 104 ⫾ 0.1 ⫻ 104 0.3 ⫻ 104 ⫾ 0.1 ⫻ 104
* p ⬍ 0.05 vs AN20 and Jej, ** p ⬍ 0.05 vs AN20. ANOVA with Tukey HSD.
CURRENT SURGERY • Volume 58/Number 6 • November/December 2001