The Effect of Storage Conditions on Mesenchymal Stem Cells in Breast Milk: A Randomized Study

Introduction: Breast milk (BM) has numerous well-known, proven health benefits; however, the mechanisms underlying these effects are still not well-defined. Recent studies have shown that BM contains mesenchymal stem cells (MSCs), which might support both the growth and development of infants as well as provide protection from acute and chronic diseases. The effect of different conditions on the cellular components of BM is still unknown. This study focuses on investigating the influence of various storage methods on the properties of BM-derived MSCs. Methods: The study involved collecting 15 mL of BM samples from 17 participating mothers within the first week postpartum. MSC isolation was conducted on three sets of 5 mL samples from each participant: freshly obtained samples, refrigerated samples for 72 hours, and samples deep-frozen at -20°C for 1 month. Poststorage, MSCs were assessed for cell count, viability, and expression of specific markers using flow cytometry. Results: Analysis revealed a significant decrease in the average count of MSCs in BM poststorage. Freshly collected BM samples showed an average MSC count of 80.588,24 ± 50.0431,96, which significantly reduced to 28.333,33 ± 10.298,57 after 72 hours of refrigeration (p < 0.05). Despite this decrease, there was no notable change in the expression of MSC positive markers. Interestingly, MSCs were undetectable in samples stored in a deep freezer for one month upon microscopic examination. Conclusion: The study demonstrates a reduction in the viability of MSCs in BM when refrigerated, yet the surviving cells maintained their characteristic surface markers. However, freezing BM resulted in a complete loss of its MSC content.