Unexpected Clot Formation in a Thawed Cryopreserved Autologous Hematopoietic Stem Cell Transplantation Product: A Case Report

A 66-year-old female with a diagnosis of multiple myeloma was admitted to our hospital in April 2025 for peripheral blood stem cell collection.Stem cells were mobilized with plerixafor (Mozobil ® , Genzyme, Massachusetts, USA) and recombinant human granulocyte colony-stimulating factor (G-CSF; filgrastim, Amgen Inc., California, USA).Leukapheresis was performed over two consecutive days using a cell separator (Spectra Optia, Terumo BCT, USA) with acid-citrate-dextrose Formula A (ACD-A) at a 1:24 ratio, supplemented with additional heparin.On day 1, a total of 3.138×10 6 CD34 + cells/kg were collected, separated into two bags (1.569×10 6 CD34 + cells/kg each), and cryopreserved for autologous stem cell transplantation at a later scheduled date.On day 2, a total of 2.422×10 6 CD34 + cells/kg were collected and cryopreserved as a reserve.All three products were cryopreserved according to the institution's standard protocol.After washing, the cell products were mixed with 10% dimethyl sulfoxide (DMSO) and 5% human serum albumin.The temperature of the product