Unlocking the promise of mesenchymal stem cells and extracorporeal photopheresis to address rejection and graft failure in intestinal transplant recipients.

Introduction: In patients with irreversible intestinal failure, intestinal transplant has become a standard treatment option. Graft failure secondary to acute or chronic cellular rejection continues to be a significant challenge following transplant. Even with optimal immune suppression, some patients continue to struggle with refractory rejection. Both extracorporeal photopheresis (ECP) and extracellular vesicles derived from mesenchymal stem cells (EVs) have been used to treat refractory rejection following intestinal transplantation, although their use remains limited and consistent treatment protocols are lacking.
Methods: Intestinal transplant recipients who received ECP only or ECP and EVs as rescue therapy for acute cellular rejection or chronic inflammation between 2016 and 2022 were included in this single-center retrospective analysis. Baseline demographics, pre- and post-treatment histopathology, endoscopic and biochemical findings, and long-term transplant outcomes were analyzed.
Results: Three patients (two pediatric and one adult) with acute steroid- and biologic-refractory rejection were treated with ECP and/or EVs, as was one patient (pediatric) with chronic graft rejection and inflammation. Patients received twice weekly ECP for 4 weeks and once weekly thereafter. EVs were administered in three doses each separated by 72 h. Immunosuppression at the time of treatment initiation included high-dose tacrolimus and sirolimus. Histologic resolution of rejection was achieved in all patients over 12-16 weeks. Steroids were weaned to low-dose or withdrawn in every patient within 4 weeks of ECP/EV treatment. C-reactive protein decreased from an average of 14.75 to 1.6 mg/dL post-treatment and fecal calprotectin decreased from average 800 mg/g to 31 mg/g. Donor-induced cytotoxic T cell populations were quantified for two of the patients with acute rejection, and in both cases decreased dramatically following treatment. There were no complications associated with either treatment.
Conclusion: Both ECP and EVs present novel opportunities to address graft rejection and inflammation in bowel transplant recipients. More work will be needed to define the optimal therapeutic parameters for each treatment modality.
Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Steven Levitte reports a relationship with Genentech Inc that includes: funding grants. SL reports grant funding unrelated to this work from Genentech Inc, South San Francisco, USA. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
(Copyright © 2024 American Society for Histocompatibility and Immunogenetics. Published by Elsevier Inc. All rights reserved.)