Efficacy and Safety of Mesenchymal Stem Cells in Improving Thrombocytopenia after Chemotherapy in Malignant Tumors

INTRODUCTION Chemotherapy-induced thrombocytopenia (CIT) is a common complication of cytotoxic chemotherapy and targeted therapies, which always contributes to morbidity and poor overall survival. There are limited therapies to prevent or treat CIT. Mesenchymal stem cells (MSC) are immunogenic multipotent stem cells derived from the mesoderm with self-renewal and multi-directional differentiation potential. They have the ability of self-replication and multi-directional differentiation potential. They not only provide mechanical support for hematopoietic stem cells in the bone marrow, but also can secrete a variety of growth factors to support hematopoietic function. It has long-term hematopoietic support function. We have explored the application of MSC to patients with CIT to improve platelet levels and reduce bleeding-related complications. METHODS We screened out 25 patients who met the CIT criteria and whose platelet count was lower than 50×10^9/L. We recorded the age, gender, tumor type, stage, whether there was combined bone marrow invasion, the number and efficacy of previous treatment lines, the condition of bone marrow hyperplasia before chemotherapy, whether CIT occurred previously, and the lowest platelet count during previous chemotherapy.We conducted a therapy for CIT patients with mesenchymal stem cells to evaluate the efficacy and safety. Patients received therapies: mesenchymal stem cells（1×10^6/u, once a week, continuous for 4 weeks as a course）. RESULTS 27 patients（F:M=13:14）with CIT had received MSC at least once, 18 of which were solid tumors, and 9 hematologic neoplasms. The median age of the patients was 58 years (24-80y). The lowest platelet level was 1×10^12/L. With MSC therapy, median treatment cycles were 1.75 cycles（7 times）. After MSC therapy, platelet levels increased in 23 patients（85%）, and the mean increase of platelet levels was 32×10^12/L. No treatment-relevant adverse reactions. CONCLUSIONS Our results show that MSC is a safe and effective method for CIT patients both in solid tumors and hematologic tumors. It indicates that the achieve efficient effectively improves the platelet level of patients with CIT, reduces the risk of bleeding and the frequency of blood transfusion, and without significantly increasing toxicity.