A cell-based potency assay for insulin-like growth factor-I

Area of Science:

• Biotechnology
• Cell Biology
• Endocrinology

Background:

• Recombinant human insulin-like growth factor I (IGF-I) requires robust bioassays for potency determination.
• Existing methods may have limitations in simplicity, precision, or applicability to modified IGF-I analogues.

Purpose of the Study:

• To develop and validate a simple, precise, and accurate cell-based bioassay for quantifying recombinant human IGF-I.
• To assess the assay's ability to detect activity of IGF-I analogues and modified samples.
• To compare the potency of IGF-I with related peptides like IGF-II and insulin.

Main Methods:

• Utilized the HU-3 human megakaryoblastic cell line for a cell proliferation assay.
• Measured cell growth using the alamarBlue fluorescence method under serum-free conditions.
• Determined dose-dependent responses and effective concentration ranges for IGF-I.

Main Results:

• The assay demonstrated a dose-dependent growth response to IGF-I within the 0.1-25 ng/ml range, with a half-maximal response at ~2 ng/ml.
• The assay successfully detected activity of truncated IGF-I analogues and modified IGF-I samples.
• Interassay variability was <10%, recovery was ~100%, and IGF-II was 5-fold less potent than IGF-I, while insulin showed minimal activity.

Conclusions:

• The HU-3 cell-based bioassay provides a simple, safe, and precise method for measuring recombinant human IGF-I biological activity.
• This assay is suitable for quality control applications and can differentiate the activity of various IGF-I related peptides.
• It offers a convenient alternative to radioactive and other colorimetric bioassays.