Ruolo del Ruxolitinib nel cross-talk tra cellule staminali mesenchimali e microambiente midollare nella mielofibrosi

Abstract

Introduction; Mesenchymal stem cells (Mesenchymal Stem Cells, MSC) are one of the most studied and well-characterized adult stem cell populations. They are excellent candidates in regenerative medicine, mainly because of their immunomodulatory properties and their emerging role in intercellular communication. MSCs as cellular components of bone marrow hematopoietic niche play a fundamental role in maintaining the physiological balance of the niche and in promoting and regulating hematopoietic stem cell (HSCs) functions, such as proliferation and "homing" to the bone marrow. - Methods: In this work, we focused on the possible internalization and release of Ruxolitinib (a JAK1/2 inhibitor by NOVARTIS Pharma) by MSC. In details, primary human MSC were isolated from bone marrow (BMMSC) of five patients diagnosed with Idiopathic Myelofibrosis or Polycythemia Vera. Diagnosis was confirmed by histopathology and molecular biology for the detection of mutations in Janus Kinase 2 receptor encoding gene, specifically for JAK2 V617F mutation. Subsequently, we evaluated the in vitro anti-proliferative effect of culture medium conditioned with Ruxolitinib on immortalized JAK2+ CD34+ SET-2 cells. Finally, a co-culture system of BMMSC and SET-2 cells treated or not with Ruxolitinib in different ratios (1:20, 1: 100 and 1: 1000) was used for estimating the relative anti-proliferative action on SET-2 cell line. - Results: Our preliminary results showed that MSCs could uptake and release Ruxolitinib in culture medium, and conditioned culture medium had more anti-proliferative effects on SET-2 cells compared to the drug alone added to the medium. In an in vitro co-culture system, the proliferation of SET-2 cells decreased by increasing MSC ratio treated with Ruxolitinib / SET-2, and BMMSC treated with Ruxolitinib had a greater anti-proliferative action on SET-2 cells compared to untreated BMMSCs. - Conclusions: Mesenchymal bone marrow stem cells could uptake and release Ruxolitinib that might increase the anti-proliferative effect of the drug on SET-2 cell line carrying the JAK2 V617F mutation. These mechanisms may contribute to amplify over time the pharmacological effects of Ruxolitinib in the bone marrow niche of Idiopathic Myelofibrosis and Polycythemia Vera patients. [edited by Author]