SUL-109 Protects Hematopoietic Stem Cells from Apoptosis Induced by Short-Term Hypothermic Preservation and Maintains Their Engraftment Potential

The newly developed 6-hydroxychromanol derivate SUL-109 was shown to provide protection during hypothermic storage of several cell lines, but has not been evaluated in hematopoietic stem cells (HSCs). Hypothermic preservation of HSCs would be preferred over short-term cryopreservation to prevent cell loss during freezing/thawing and would be particularly useful for short-term storage, such as during conditioning of patients or transport of HSC transplants. Here we cultured human CD34 umbilical cord blood (UCB) cells and lineage-depleted (Lin) Balb/c bone marrow (BM) cells for up to 7 days in serum-free HSC expansion medium with hematopoietic growth factors. SUL-109-containing cultures were stored at 4°C for 3 to 14 days. The UCB cells were tested for viability, cell cycle, and reactive oxygen species (ROS). DMSO-cryopreserved Lin BM cells or Lin BM cells maintained for 14 days at 4°C were transplanted into RAG2 Balb/c mice and engraftment was followed for 6 months. The addition of SUL-109 during the hypothermic storage of expanded CD34 UCB cells provided a significant improvement in cell survival of the immature CD34/CD38 fraction after 7 days of hypothermic storage through scavenging of hypothermia-induced ROS and was able to preserve the multilineage capacity of human CD34 UCB cells for up to 14 days of cold storage. In addition, SUL-109 protected murine BM Lin cells from 14 days of hypothermic preservation and maintained their engraftment potential after transplantation in immune-deficient RAG2 mice. Our data indicate that SUL-109 is a promising novel chemical for use as a protective agent during cold storage of human and murine HSCs to prevent hypothermia-induced apoptosis and promote cell viability.