Tips and tricks in cryopreservation of hematopoietic stem cells: critical points to keep under control

Background aims: Several studies demonstrated that under standard conditions, CD34+ hematopoietic stem cells remained viable after cryopreservation for up to 19 years. However, to ensure high-quality cellular products, it is essential to define control points throughout the HSC manipulation process and validate any critical procedure. The main aim of this study is the description of the validation plan used to analyze the cryopreservation procedure and its correlation with the clinical outcome of the procedure. Methods: A validation plan was defined based on an FMEA risk assessment used to identify critical control points of the whole process. A careful risk analysis allows keeping the critical aspects of the process under control to guarantee patient safety. Results: Data about neutrophil and platelet engraftment confirmed the impact of the validation process on the success of the transplantation procedure. We also analyzed CD34+ viability in relation to total nucleated cells (TNC) concentration (cells/mL) in cryopreserved cellular products collected over the past three years (2023-2025). Conclusions: This work provides a practical guide for operators, offering clear indications on how to manage and control each critical step of the HSC cryopreservation process to ensure product quality and patient safety.