S. Santiago

Intestinal and Multivisceral Transplantation in Children

Objective:To describe a single-center experience of pediatric intestinal transplantation (Itx) and to provide an overview of the children who underwent this procedure along with their outcomes. Summary Background Data:Pediatric Itx presents multiple challenges because of the very young ages at which patients require transplantation and their higher susceptibility to infectious complications. Methods:We have performed 141 Itx in 123 children with a median age of 1.37 years. Primary grafts included isolated intestine (n = 28), liver and intestine (n = 27), multivisceral (n = 61), and multivisceral without the liver (n = 7). Two protocol modifications were introduced in 1998: daclizumab induction and frequent rejection surveillance. In 2001, indications for multivisceral transplantation were expanded, and induction with Campath-1H was introduced. Results:Actuarial patient survival at 1 and 3 years for group 1 (January 1994 to December 1997, n = 25), group 2 (January 1998 to March 2001, n = 29), group 3a (April 2001 to present, daclizumab, n = 51), and group 3b (April 2001 to present, Campath-1H, n = 18) was 44%/32%, 52%/38%, 83%/60%, and 44%/44%, respectively (P = 0.0003 in favor of group 3a). Severe rejection implied a dismal prognosis (65% mortality at 6 months). Observed incidence of severe rejection in groups 1, 2, 3a, and 3b was 32%, 24%, 14%, and 11%, respectively. In multivariable analysis, use of a multivisceral (with or without liver) transplant (P = 0.002), induction with daclizumab (P = 0.005), patient at home prior to transplant (P = 0.007), and age at transplant ≥1 year (P = 0.02) favorably influenced patient survival. Multivisceral transplant was protective with respect to the mortality rate due to rejection, while an older age at transplant was associated with both a lower incidence rate of developing respiratory infection and lower risk of mortality following the respiratory infection. Survivors are off parenteral nutrition and have demonstrated significant growth catch-up. Conclusions:Itx in children still is a high-risk procedure but has now become a viable option for children who otherwise have no hope for survival. Control of respiratory infection is of particular importance in the younger children.

Heterotopic Uterus Transplantation in a Swine Model

Background. The aim of our study was to examine the feasibility of allogeneic uterine transplantation in a large animal model. Methods. We performed heterotopic uterine transplants in genetically defined mini-pigs. Immunosuppression was tacrolimus administered intravenously for the first 12 days posttransplantation followed by oral cyclosporine maintenance immunosuppression. The graft was transplanted heterotopically in the lower abdominal cavity of the recipient. The vaginal vault was exteriorized as a stoma in the lower right abdominal wall. The uterine grafts were followed with endoscopies and biopsies. Results. Ten transplants were performed. Follow-up was until July 2008. At the end of the follow-up period, 5 animals were alive and healthy, 0.5 to 12 months posttransplantation. There were 5 deaths due to pneumonia (n=1), intussusception of the graft (n=1), cardiorespiratory arrest during anesthesia (n=1), and complications of the stoma (n=2). Acute rejections of the graft presented during the 2nd and 3rd month posttransplantation were treated successfully with increase of the maintenance immunosuppression and steroids. Other complications included prolapse and infections of the graft stoma. Pathological changes seen in the endometrial biopsies included acute rejection and acute endometritis. Conclusion. These findings demonstrate that successful uterus transplantation in a large animal model (miniature swine) is feasible using this heterotopic model, and it can be useful for the study of these transplants.

Heterotopic sternum transplant in rats: A new model of a vascularized bone marrow transplantation.

We introduced the heterotopic vascularized sternum transplant as a more simple and pure alternative to allogeneic hind limb transplantation for the study of bone marrow transplantation. We report the clinical and histopathological manifestations after transplantation of syngeneic and allogeneic sternal grafts with and without immunossupression with FK‐506. Syngeneic grafts maintained normal histology, whereas allografts showed rejection, which was prevented by FK‐506. FK‐506‐treated allografts developed chimerism that was present throughout the observation period. Transplantation of the sternum may be a valuable model to study vascularized bone marrow transplantation and its effects on repopulation of bone marrow of the host, chimerism, and tolerance.

Uterus Transplantation Model in Sheep With Heterotopic Whole Graft and Aorta and Cava Anastomoses

Uterine transplantation in the sheep model has been described as a partial or whole orthotopic graft from a living donor with vascular anastomoses. As an alternative to surrogate pregnancy or adoption uterus transplantation might be indicated for cases of infertility of uterine origin. The main complications might be rejection and thrombosis. The objective of this work was to develop a model of whole uterus transplantation that was applicable to the human setting, using grafts obtained from brain-dead donors, and suitable for immunologic and viability follow-up with a reduced risk of thrombosis. Two donors and 1 recipient were operated. The first graft was used for an anatomic study; the second was used for transplantation. The donor operation consisted of an en bloc harvest of the uterus, adnexa, and proximal vagina with the distal aorta and cava. After harvest the donor sheep was humanely killed. In the recipient ewe, heterotopic implantation was performed in the lower abdomen. An End-to-side anastomoses of aorta and cava were performed below the recipients renal vessels. A cutaneous vaginal stoma was performed in the right lower quadrant. The recipient ewe was humanely killed for an autopsy study. The anatomy of uterine veins of the ewe differs from the human. The uterine and ovarian veins join, forming the utero-ovarian vein, which drains at the confluence of the common iliac to the cava. En bloc harvesting allows for rapid graft preparation, with vascular cuffs easily anastomosed with a low risk of thrombosis. The vaginal stoma seems appropriate to facilitate follow-up and graft biopsy. This approach can be a suitable experimental model applicable to humans using grafts from brain-dead donors.

Anastomotic Healing in a Small Bowel Transplantation Model in the Rat

Anastomotic healing is impaired after intestinal surgery because of ischemia and reperfusion injury (IRI), which can result in intestinal leaks leading to increased mortality. The objective of this study was to determine the effects of transplant IRI and immune mechanisms on intestinal graft anastomotic healing. Orthotopic intestinal transplantations (OIT) were performed in rats. The experimental design consisted of six groups A–F (n = 5/group): A, allogeneic OIT treated with tacrolimus (1mg/kg/day); B, syngeneic OIT treated with tacrolimus; C, syngeneic OIT; D, allogeneic OIT; E, proximal and distal anastomoses performed in nontransplanted animals; F, same as in group E but treated with tacrolimus. Anastomotic bursting pressure (ABP), hydroxyproline content (HPC), and mucosal inflammatory infiltrate (MII) were determined at the anastomotic sites (proximal and distal) and compared between groups. ABP was significantly (p < 0.001) reduced in OIT groups A, B, C, and D compared to control groups E and F at both the proximal and distal anastomotic sites. HPC was ∼1 μg/mg of tissue in groups A, B, C, and D, and ∼5μg/mg of tissue in groups E and F. This demonstrates a significant (p < 0.001) reduction in HPC after OIT. MII was significantly (p < 0.001) increased in OIT groups when compared to nontransplanted control groups. MII was also significantly (p < 0.05) increased in allogeneic OIT groups A and D compared to syngeneic OIT groups B and C. Generally, ABP and HPC were inversely proportional to MII in both nontransplanted control and OIT groups. Reduced anastomotic strength was demonstrated in both syngeneic and allogeneic OIT anastomotic sites irrespective of immunosuppressive therapy, and is probably related to IRI.

Tacrolimus does not upregulate mucin gene expression after small bowel transplantation in rats.

properties, and to produce similar effects. 4 Tacrolimus is the primary immunosuppressive agent used for intestinal transplantation. In this study, we investigated the in vivo effects of tacrolimus on goblet cell proliferation and mucin production in a rat, SBTx model.