(A-C) C57BL/6 mice were exposed to 3-day CS and injected i.v. with 3 × 105 hASC not transfected (ASCNT), transfected with TSG-6 siRNA (ASCTS), or with scrambled siRNA (ASCSC) on Day 2. Mean ± SEM, n = 6/group. ap < 0.05 (vs. AC); bp < 0.05, (vs. vehicle). (D) In vitro model of CS-induced myelosuppression demonstrating direct antagonist effects of hASC, ASC-CM, and rhTSG-6 against the toxicity of CS extract (CSE) on GM-CFU. Mouse BM cells were treated in vitro with 1.5% CSE with or without hASC (3 × 104/cm2) / ASC-CM (20%, v/v) / rhTSG-6 (500 ng/ml) in methylcellulose medium supplemented with FBS, mGM-CSF (10 ng/ml) & mSCF (50 ng/ml) for 7 days. Mean ± SEM, n = 3/group; ap < 0.05, (vs. non-treated control); bp < 0.05, vs. (CSE + vehicle). ASCNT = Non-transfected ASC; ASCTS = TSG-6 siRNA-transfected; ASCSC = scramble siRNA-transfected.