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Updated: May 9, 2026
Longitudinal In Vivo Imaging and Quantification of Human Pancreatic Islet Grafting and Contributing Host Cells in the Anterior Eye Chamber
Published on: June 11, 2020
Quantification of islet loss and graft functionality during immune rejection by 3-tesla MRI in a rat model
Sophie Borot1, Lindsey A Crowe, Géraldine Parnaud
1Cell Isolation and Transplant Center, Department of Surgery, University of Geneva and Geneva University Hospitals, Geneva, Switzerland.
Background:
Because metabolic markers are not suitable for early diagnosis of islet graft dysfunction, magnetic resonance imaging (MRI) has been used to study islets that were labeled pretransplantation with superparamagnetic iron oxide nanoparticles. However, the relation between graft functionality assessed by glycemia, and MRI signal remains unclear.
Methods:
We transplanted hyperglycemic rats intraportally with 2500 ferucarbotran-labeled syngeneic (n=10) or allogeneic (n=12) islet equivalents or normoglycemic rats with 5000 xenogeneic human islet equivalents. Images were acquired on a clinical 3-Tesla MRI scanner.
Results:
When rejection occurred on days 4 and 8 in xenogeneic and allogeneic recipients, 60% (57-68) and 55% (46-73) of the initial signal remained compared to 93% (71-104) and 82% (59-90) in syngeneic controls (P=0.006 and 0.03). With a cutoff value of 84% on day 4 for the diagnosis of allogeneic rejection, sensitivity of 91% and specificity of 70% were obtained. Based on MRI signal on day 4, treatment with antilymphocytic serum from day 4 allowed graft rescue in 75% of recipients.
Conclusions:
In this model, MRI of pretransplantation superparamagnetic iron oxide nanoparticle-labeled islet grafts allows timely diagnosis of immune rejection.
Insights
Magnetic resonance imaging (MRI) of superparamagnetic iron oxide nanoparticle-labeled islet grafts can detect immune rejection early. This method aids in timely diagnosis, improving islet graft survival and function.
Area of Science:
- Transplantation immunology
- Medical imaging
- Islet cell research
Background:
- Metabolic markers are insufficient for early diagnosis of islet graft dysfunction.
- Superparamagnetic iron oxide nanoparticle (SPIO)-labeled islets are studied using MRI.
- The relationship between MRI signal and islet graft function (assessed by glycemia) is unclear.
Purpose of the Study:
- To investigate the utility of MRI for diagnosing immune rejection in islet grafts.
- To correlate MRI signal changes with islet graft functionality and rejection status.
Main Methods:
- Islet equivalents labeled with ferucarbotran were transplanted into rats (syngeneic, allogeneic, and xenogeneic models).
- Intraportal islet transplantation was performed in hyperglycemic and normoglycemic rats.
- Magnetic resonance imaging (MRI) was conducted using a clinical 3-Tesla scanner.
Main Results:
- MRI signal significantly decreased in rejected allogeneic and xenogeneic grafts compared to syngeneic controls.
- A cutoff MRI signal of 84% on day 4 achieved 91% sensitivity and 70% specificity for detecting allogeneic rejection.
- Treatment with antilymphocytic serum based on day 4 MRI signal rescued grafts in 75% of recipients.
Conclusions:
- MRI of SPIO-labeled islet grafts enables early detection of immune rejection.
- This imaging technique can facilitate timely intervention and improve islet graft outcomes.
