Islet cell culture in defined serum-free medium

Area of Science:

• Cell Biology
• Endocrinology
• Biochemistry

Background:

• Primary islet cell cultures and continuous cell lines are crucial for studying pancreatic beta-cell function and diabetes.
• Maintaining functional activity, particularly glucose-stimulated insulin secretion (GSIS), in vitro is challenging due to the need for specific culture conditions.
• Serum-containing media pose variability and undefined components, necessitating the development of defined, serum-free alternatives.

Purpose of the Study:

• To develop and validate a serum-free, defined medium that supports the long-term functional activity of primary adult islet cells and continuous islet cell lines.
• To identify essential supplements for maintaining glucose-stimulated insulin secretion (GSIS) in cultured islet cells.
• To establish a reliable in vitro model for studying pancreatic beta-cell physiology and potentially for therapeutic applications.

Main Methods:

• Primary adult rat islet cells and beta-cell lines (HIT-T15, RINr 1046-38) were cultured in serum-free media supplemented with various hormones and growth factors.
• The effects of supplements including proteose peptone (PP), transferrin (TrFe), insulin-like growth factor-I (IGF-I), ethanolamine (EA), phosphoethanolamine (PEA), and human serum albumin (HSA) were evaluated.
• Functional activity was assessed by measuring glucose-stimulated insulin secretion using static incubations and a superfusion system under low and stimulatory glucose concentrations.

Main Results:

• A defined medium combining HSA (1 mg/ml), EA (50 microM), PEA (50 microM), TrFe (10 micrograms/ml), T3 (0.1 nM), IGF-I (0.65 nM), and PRL (1 nM) successfully replaced undefined proteose peptone.
• Islet monolayers cultured in this defined medium for 3 weeks exhibited biphasic glucose-induced insulin secretion indistinguishable from cells cultured in 5% fetal bovine serum.
• The defined medium maintained functional activity of both primary islet cells and beta-cell lines (HIT-T15, RINr 1046-38) for extended culture periods.

Conclusions:

• A novel serum-free defined medium effectively supports the functional activity and glucose responsiveness of primary adult rat islet cells and beta-cell lines.
• The combination of HSA, EA, PEA, TrFe, T3, IGF-I, and PRL is critical for sustaining GSIS in vitro.
• This defined medium provides a robust platform for islet cell research and holds potential for developing media for human islet cell culture.