Ectoine-based cryopreservation of human cells: a systematic review of efficacy and safety

Cryopreservation is crucial for research and cell therapies, but common cryoprotectants like dimethyl sulfoxide may cause toxicity. Ectoine and hydroxyectoine are natural compatible solutes proposed as safer alternatives or adjuncts. We performed a systematic review of experimental studies that tested Ectoine or hydroxyectoine in human cell cryopreservation up to 16 November 2025. Fifteen studies met inclusion criteria and were examined for cell types, cryoprotective agents (CPA) formulations, freezing and thawing methods, viability, functional readouts, toxicity, and mechanistic data. Results were heterogeneous but consistent in one central finding: ectoine/hydroxyectoine most often improved short-term membrane integrity and preserved structural or functional markers when used in multi-component cocktails (polymers, sugars, antioxidants, or low doses of penetrating CPAs). Single-agent Ectoine frequently fell short of standard 10% dimethyl sulfoxide performance for several cell types, and very high Ectoine concentrations sometimes harmed cells. Mechanistic work suggests Ectoine acts extracellularly by stabilizing hydration shells and membranes rather than by preventing intracellular ice, explaining why it works best in complementary combinations. Overall, Ectoine and hydroxyectoine appear promising for dimethyl sulfoxide-sparing strategies, but standardized dose-response studies, head-to-head comparisons, and more toxicity and functional testing are required before clinical translation.