Size-based separation and collection of mouse pancreatic islets for functional analysis

Area of Science:

• Biomedical Engineering
• Endocrinology
• Cell Biology

Background:

• Islet size is a critical factor influencing human islet transplantation outcomes.
• Effective methods for isolating islets based on size are needed for optimizing transplantation strategies.

Purpose of the Study:

• To develop and validate a microfluidic device for size-based separation of mouse pancreatic islets.
• To assess the functional capacity of size-separated islets to inform transplantation protocols.

Main Methods:

• Fabrication of a multi-layered microfluidic device using soft lithography and polydimethylsiloxane (PDMS).
• Demonstration of size-based separation using glass beads (50-300 micrometers) and subsequent separation of mouse islets (50-250 micrometers).
• Evaluation of islet viability post-separation using cell viability staining and assessment of glucose-stimulated insulin secretion (GSIS).

Main Results:

• The microfluidic device successfully separated heterogeneous populations of glass beads and mouse islets into distinct size-based sub-populations.
• Islets remained intact and viable throughout the separation process, showing no signs of damage.
• Islets smaller than 150 micrometers exhibited significantly higher stimulation indexes (SI) compared to larger islets.
• The greatest SI was observed in islets measuring between 100 and 150 micrometers in diameter.

Conclusions:

• Microfluidic technology enables efficient and non-damaging size-based separation of pancreatic islets.
• Islet size is a key determinant of functional capacity, with smaller islets (<150 micrometers) demonstrating superior insulin secretory function.
• This size-based separation approach holds promise for improving islet transplantation by selecting functionally superior islet populations.