Blocking of the potential candidate TGFB in supernatants derived from MGUS, SMM and MM restores differentiation capacity of co-cultured healthy MSC. (A) Study design for coculture of healthy MSC with conditioned media (CM) from MGUS, SMM, and MM patients. MSC were cultured with CM from healthy, MGUS, SMM, or MM MNC for 3 days. Representative micrographics of the phenotype of healthy MSC after exposure to supernatants from MGUS-, SMM-, and MM-derived MNC for 3 days with scale bars indicating 100 μm. Bar charts of cell number after exposure to supernatants from MGUS, SMM, and MM MNC as well as the MM cell line INA-6. (B) Healthy MSC were treated 3 days with TGFB1 and representative pictures show phenotype of untreated healthy control and after exposure to TGFB1. Scale bars indicating 100 μm. (C) Expression TPM-values (transcripts per kilobase million) from our RNA sequencing data for TGFB1, BMP8B, and BMP2 from our MGUS, SMM, and MM MSC samples in comparison to 48 patients samples with diffuse large B-cell lymphoma from the database OncoDB. (D) Coculture of healthy MSC with CM from healthy, MGUS, SMM, and MM MNC. To analyze and inhibit potential TGFB1 inducing effects, the potent ATP-competitive TGF-βRI inhibitor SD208 was added to CM from healthy, MGUS, SMM, and MM-derived MNC. DMSO containing CM served as control group. Healthy MSC were co-cultured with respective CM for 3 days. Representative micrographs of the morphology of healthy MSC cocultured with CM supplemented with DMSO or SD208 are shown. Inner pictures show Alizarin Red staining of 14 days osteogenic induced healthy MSC after the period of 3 days of exposure to respective condition (CM MGUS, SMM, MM + DMSO, or +SD208). Scale bars indicating 100 μm.