Donor's graft ex vivo T-cell depletion with fludarabine reduces graft-versus-host disease signs and improves survival after intestinal transplantation - an experimental study

Preclinical Study of DCD and Normothermic Perfusion for Visceral Transplantation

Considering recent clinical and experimental evidence, expectations for using DCD-derived intestines have increased considerably. However, more knowledge about DCD procedure and long-term results after intestinal transplantation (ITx) is needed. We aimed to describe in detail a DCD procedure for ITx using normothermic regional perfusion (NRP) in a preclinical model. Small bowel was obtained from pigs donors after 1 h of NRP and transplanted to the recipients. Graft Intestinal samples were obtained during the procedure and after transplantation. Ischemia-reperfusion injury (Park-Chiu score), graft rejection and transplanted intestines absorptive function were evaluated. Seven of 8 DCD procedures with NRP and ITx were successful (87.5%), with a good graft reperfusion and an excellent recovery of the recipient. The architecture of grafts was well conserved during NRP. After an initial damage of Park-chiu score of 4, all grafts recovered from ischemia-reperfusion, with no or very subtle alterations 2 days after ITx. Most recipients (71.5%) did not show signs of rejection. Only two cases demonstrated histologic signs of mild rejection 7 days after ITx. Interestingly intestinal grafts showed good absorptive capacity. The study's results support the viability of intestinal grafts from DCD using NRP, contributing more evidence for the use of DCD for ITx.

Native Spleen Preservation During Visceral Transplantation Inhibits Graft-Versus-Host-Disease Development: Clinical and Experimental Study

OBJECTIVE

We aimed to assess whether native spleen preservation during visceral transplantation (VT) affects graft-versus-host-disease (GVHD) incidence.

SUMMARY BACKGROUND DATA

GVHD is one of the most severe and frequently lethal hematological complications after VT procedures. Because there is no specific treatment for GVHD, it is imperative to develop a strategy to reduce donor lymphocyte engraftment and proliferation.

METHODS

Our study included both clinical and experimental data. A total of 108 patients were divided into 3 groups: a native spleen preservation group, a native spleen removal with no donor spleen group, and a donor spleen included (allogeneic spleen) group. We also used an allogeneic VT rat model, in which recipients were divided into 2 groups: a native spleen preservation (+SP) group and a native spleen removal (-S) group. Skin rash appearance, histopathological changes, chimerism, and spleen effects on circulating allogeneic T-cells were assessed.

RESULTS

The patients with native spleen preservation showed a lower rate of GVHD ( P <.001) and better survival ( P <.05) than those in the other groups. Skin and histological signs of GVHD were lower in the rats in the +SP group ( P <.05). The donor T-cell frequency in the bloodstream and skin was also significantly reduced when the native spleen was preserved ( P <.01 and P <.0001, respectively).

CONCLUSIONS

The clinical and experimental data indicate that recipient spleen preservation protects against GVHD after VT, and donor cell clearance from the bloodstream by spleen macrophages could be the underlying mechanism. Therefore, spleen preservation should be considered in VT procedures, whenever possible.

Innovations in Immunosuppression for Intestinal Transplantation

It has been 57 years since the first intestinal transplant. An increased incidence of graft rejection has been described compared to other solid organ transplants due to high immunogenicity of the bowel, which in health allows the balance between of dietary antigen with defense against pathogens. Expanding clinical experience, knowledge of gastrointestinal physiology and immunology have progress post-transplant immunosuppressive drug regimens. Current regimes aim to find the window between prevention of rejection and the risk of infection (the leading cause of death) and malignancy. The ultimate aim is to achieve graft tolerance. In this review we discuss advances in mucosal immunology and technologies informing the development of new anti-rejection strategies with the hope of improved survival in the next generation of transplant recipients.

Intestinal transplantation: an overview of the recent experimental studies

PURPOSE OF REVIEW

Experimental intestinal transplantation (ITx ) has generated invaluable knowledge that has ultimately benefited the clinical activity. Herein, we appraise the recent publications pertaining to experimental ITx and highlight the main current research topics.

RECENT FINDINGS

During the recent years, ischemia-reperfusion injury (IRI) and Graft-versus-host disease (GVHD) have gradually replaced acute rejection as the main research topic. New additives to established preservation solutions and relatively novel approaches such as luminal interventions during cold storage may prolong the storage time and alleviate IRI. High donor age does not seem to worsen preservation injury. The ischemic susceptibility seems to differ between species, which may impact the translatability of the experimental findings. A new experimental model of modified multivisceral transplantation including the donor spleen may offer a new tool with which to study GVHD, besides the classical Lewis-Brown Norway rat combination. Flushing the graft with fludarabine may mitigate GVHD in rats. T-cell activation inhibitor-mitochondrial was downregulated in the peripheral blood leukocytes before other signs of acute and severe chronic rejection could be observed.

SUMMARY

Experimental research in ITx has largely shifted focus from acute rejection to IRI and GVHD. Several lines of research have matured toward clinical translation, yet no breakthrough is imminent.