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Transplant Direct. 2019 Apr 15;5(5):e447. doi: 10.1097/TXD.0000000000000890. eCollection 2019 May.

Preliminary Studies of the Impact of CXCL12 on the Foreign Body Reaction to Pancreatic Islets Microencapsulated in Alginate in Nonhuman Primates.

Author information

1
Department of Infectious Diseases, Vaccine and Immunotherapy Center, Massachusetts General Hospital, Boston, MA.
2
Division of Transplant Surgery, The Pancreas/Islet Transplant Program, Massachusetts General Hospital, Boston, MA.
3
Clinical Islet Program, Surgery School of Medicine, University of California Irvine, Irvine, CA.
4
Department of Surgery, Institute for Cellular Transplantation, University of Arizona, Tucson, AZ.
5
ViCapsys, Inc., Athens, GA.
6
Department of Surgery, University of Minnesota, Minneapolis, MN.
7
Department of Pathology and Medical Biology, University of Groningen, Groningen, The Netherlands.

Abstract

Background:

We previously demonstrated that the incorporation of the chemokine CXCL12 into alginate microbeads supported long-term survival of microencapsulated auto-, allo-, and xenogeneic islets in murine models of diabetes without systemic immune suppression. The purpose of this study was to test whether CXCL12 could abrogate foreign body responses (FBRs) against alginate microbeads which were empty or contained autologous islets in healthy nonhuman primates (NHPs; n = 4).

Methods:

Two NHPs received intraperitoneal implants of 400 000 alginate microbeads with or without CXCL12, and postimplantation immunological and histopathological changes were evaluated up to 6 months postimplantation. A similar evaluation of autologous islets in CXCL12-containing alginate microbeads was performed in NHPs (n = 2).

Results:

CXCL12-containing alginate microbeads were associated with a markedly reduced FBR to microbeads. Host responses to microbead implants were minimal, as assessed by clinical observations, blood counts, and chemistry. Evaluation of encapsulated islets was limited by the development of necrotizing pancreatitis after hemipancreatectomy in 1 NHP. A limited number of functioning islets were detectable at 6 months posttransplantation in the second NHP. In general, empty microbeads or islet-containing beads were found to be evenly distributed through the intraperitoneal cavity and did not accumulate in the Pouch of Douglas.

Conclusions:

Inclusion of CXCL12 in alginate microbeads minimized localized FBR. The NHP autologous islet implant model had limited utility for excluding inflammatory/immune responses to implanted islets because of the complexity of pancreatic surgery (hemipancreatectomy) before transplantation and the need to microencapsulate and transplant encapsulated autologous islets immediately after pancreatectomy and islet isolation.

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