Optimizing Post-Transplantation Detection of Subcutaneously Transplanted Islets Using Dithizone Staining.

Area of Science:

• Endocrinology
• Cell Biology
• Transplantation Science

Background:

• Pancreatic islet transplantation aims to restore insulin independence in type 1 diabetes mellitus.
• Human pluripotent stem cell-derived islets (SC-islets) show clinical promise.
• Optimizing transplantation sites and graft localization are key challenges.

Purpose of the Study:

• To investigate dithizone staining for reliable localization of transplanted islet grafts in the subcutaneous space of murine models.
• To address limitations in standardized islet dosing and post-transplant graft localization.

Main Methods:

• SC-islets and primary human islets were generated and functionally validated.
• Islet volume was standardized using automated islet equivalent quantification.
• Islets were transplanted into the subcutaneous space of immunodeficient mice.
• Graft function was assessed via blood glucose monitoring, glucose tolerance testing, and C-peptide measurements.
• Dithizone staining and immunohistochemistry were used for graft localization and validation.

Main Results:

• Automated quantification ensured consistent islet dosing.
• Transplanted islets maintained function in vivo, evidenced by improved glycemic control and C-peptide detection.
• Dithizone staining provided clear, selective labeling of β-cell grafts, enabling reliable localization and recovery.
• Immunohistochemistry confirmed insulin-expressing cells within isolated grafts.

Conclusions:

• Dithizone staining offers a rapid, cost-effective method for identifying subcutaneous islet grafts.
• This technique addresses a significant limitation in islet transplantation research.
• Combined with standardized islet quantification, it provides a reproducible framework for evaluating subcutaneous islet transplantation.