Induction of Chimerism Permits Low-Dose Islet Grafts in the Liver or Pancreas to Reverse Refractory Autoimmune Diabetes

Abstract

OBJECTIVETo test whether induction of chimerism lowers the amount of donor islets required for reversal of diabetes and renders the pancreas a suitable site for islet grafts in autoimmune diabetic mice.RESEARCH DESIGN AND METHODSThe required donor islet dose for reversal of diabetes in late-stage diabetic NOD mice after transplantation into the liver or pancreas was compared under immunosuppression or after induction of chimerism. Recipient mice were monitored for blood glucose levels and measured for insulin-secretion capacity. Islet grafts were evaluated for β-cell proliferation, β-cell functional gene expression, and revascularization.RESULTSWith immunosuppression, transplantation of 1,000, but not 600, donor islets was able to reverse diabetes when transplanted into the liver, but transplantation of 1,000 islets was not able to reverse diabetes when transplanted into the pancreas. In contrast, after induction of chimerism, transplantation of as few as 100 donor islets was able to reverse diabetes when transplanted into either the liver or pancreas. Interestingly, when lower doses (50 or 25) of islets were transplanted, donor islets in the pancreas were much more effective in reversal of diabetes than in the liver, which was associated with higher β-cell replication rate, better β-cell functional gene expression, and higher vascular density of graft islets in the pancreas.CONCLUSIONSInduction of chimerism not only provides immune tolerance to donor islets, but also markedly reduces the required amount of donor islets for reversal of diabetes. In addition, this process renders the pancreas a more superior site than the liver for donor islets in autoimmune mice.

Induction of Mixed Chimerism Depletes Pre-existing and De Novo–Developed Autoreactive B Cells in Autoimmune NOD Mice

“…Although induction of chimerism alone was not able to reverse late-stage T1D that has little or no residual islet b-cells, combination therapy with administration of growth factors was able to augment b-cell neogenesis and cure a majority of late-stage T1D (23). In addition, induction of chimerism allowed a small numbers of donor islets (1 of 20 of regular dose) to reverse late-stage T1D after implanting islet grafts in the liver or native pancreas (26). Therefore, induction of mixed chimerism is an important curative therapy for late-stage T1D.…”

“…Antibodies for CD24(30-F1), CD4(GK1.5), IgM(II/41) IgD (11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26), BP1(6C3), CD19(eBio1D3), CD43(eBioR2/60), and CD23(B3B4) as well as efluor 450-labeled streptavidin were purchased from eBioscience (San Diego, CA). Dead cells were excluded using DAPI or aqua fluorescent reactive dye (Invitrogen, Carlsbad, CA).…”

“…Dead cells were excluded using DAPI or aqua fluorescent reactive dye (Invitrogen, Carlsbad, CA). FACS analyses were performed using the CyAn immunocytometry system (Dako Cytomation, Fort Collins, CO), and data were analyzed using FlowJo software (TreeStar, San Carlos, CA) as described in our previous publications (19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30)(31)(32).…”

“…We have demonstrated that induction of mixed chimerism via hematopoietic cell transplantation (HCT) is an effective therapy to reverse autoimmune T1D in NOD mice, using a radiation-free nontoxic anti-CD3/CD8 conditioning regimen (19)(20)(21)(22)(23)(24)(25)(26). Induction of chimerism…”

MHC-mismatched mixed chimerism augments thymic regulatory T-cell production and prevents relapse of EAE in mice

“…However, induction of MHC-mismatched mixed chimerism is able to reverse autoimmunity in mouse models (10,11). In particular, we have reported that induction of mixed chimerism under a radiation-free anti-CD3/CD8 conditioning regimen reversed autoimmune type 1 diabetes (T1D) and systemic lupus (12)(13)(14)(15)(16)(17)(18)(19). Induction of MHC-mismatched mixed chimerism can restore central tolerance by deleting autoreactive thymocytes with cross-reactivity (18), and tolerize residual T cells in the periphery and delete preexisting and immature autoreactive B cells (15,17).…”