W228 - Impact of Pre-transplant Conditionings on Bone Marrow Stromal Cells (MSCs) in Immune Dysregulation Disorders

Fatemeh Asgari – San Raffaele Telethon Institute for Gene Therapy; Ludovica Santi – San Raffaele Telethon Institute for Gene Therapy; Gaia Alberti – San Raffaele Telethon Institute for Gene Therapy; Margherita Berti – San Raffaele Telethon Institute for Gene Therapy; Anna Villa – San Raffaele Telethon Institute for Gene Therapy; Alessandro Aiuti – San Raffaele Telethon Institute for Gene Therapy, San Raffaele Scientific Institute, Vita-Salute San Raffaele University; Maria Ester Bernardo – San Raffaele Telethon Institute for Gene Therapy, San Raffaele Scientific Institute, Vita-Salute San Raffaele University; Stefano Volpi – Autoinflammatory Diseases and Immunodeficiencies Centre, IRCCS Istituto Giannina Gaslini; Maria Carmina Castiello – San Raffaele Telethon Institute for Gene Therapy; Stefania Crippa – San Raffaele Telethon Institute for Gene Therapy

Abstract Text: Mesenchymal stromal cells (MSCs) regulate hematopoietic stem and progenitor cells (HSPC) homeostasis within the bone marrow (BM) niche and result functionally impaired after common preparative conditionings, reducing the BM ability to receive transplanted cells and increasing the graft versus host disease risk after transplants. The BM niche maintenance is fundamental to improve the HSCT success in immune dysregulation disorders. Thus, we isolated and characterized MSCs from patients and mouse models of these diseases, and we evaluated the standard preparative conditionings effects over non-genotoxic approaches on MSCs. Preliminary results showed that wild-type (WT) mice-derived MSCs have a fibroblast-like morphology, express canonical surface markers, can mesodermal differentiate and support HSPCs. On the contrary, we observed a reduced clonogenic capacity and impaired proliferation, and a trend in altered gene expression and phenotype in MSCs derived from recombination-activating genes (RAG)-deficient mice. Moreover, irradiation-based conditioning reduced MSCs number and increased expression of supportive genes in WT and affected murine MSCs, with impairment in their clonogenic capacity.
Human MSCs from patients affected by Mevalonate Kinase Deficiency (MKD) and Wiskott Aldrich syndrome (WAS) showed a stable growth in culture. However, we found an altered expression of supportive genes and a reduced CD146 expression in WAS-MSCs. Patient-derived MSCs appeared impaired in terms of anti-inflammatory and ROS-involved factors in basal conditions and/or after in vitro stimuli. In vitro irradiated human MSCs showed a growth drop compared to the untreated counterpart.
MSCs interaction within the niche after preparative conditionings will be further investigated using in vitro and in vivo models.