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ATRA protects impaired BM MSC in ITP
and +13 CpG sites, respectively. DNA methylation of the IL-1β promoter and mRNA levels were inversely correlat- ed (R2 = 0.5925, P<0.001, Spearman rank correlation rho) (Figure 4L). Above all, in the presence of ATRA, IL-1β expression in MSC-ITP-C+ was alleviated and this modifi- cation was associated with hypermethylation.
All-trans retinoic acid directed the functional recovery of bone marrow mesenchymal stem cells of mice with immune thrombocytopenia
CD61+ SCID mice engrafted with 5×104 splenocytes
from CD61 knockout (KO) mice immunized against CD61+-platelets exhibited profound thrombocytopenia34 (Online Supplementary Figure S8) and some animals died of bleeding within 2-3 weeks after transfer. Platelet counts were significantly lower in ITP mice than in wild-type (WT) mice (68.73±38.76×109/L vs. 1054.07±138.93×109/L, respectively; P=0.000) (Figure 5A). The phenotypes of mice bone marrow MSC were determined by flow cytometry. The results showed that these cells were homogenously positive for the mesenchymal markers CD29, CD90 and CD105, but negative for the hematopoi-
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IJK
Figure 5. (H) Left: expression of CXCL12 (red) and CD31 (vascular endothelium, green) in the bone marrow niche assayed by marrow immunohistochemistry of WT mice, ITP mice, ITP mice treated with ATRA 5 mg/kg intraperitoneal injection and ITP mice treated with ATRA 20 mg/kg intraperitoneal injection. Right: Hematoxylin & eosin staining of marrow sections from WT mice, ITP mice, ITP mice treated with 5 mg/kg intraperitoneal injection and ITP mice treated with 20 mg/kg intraperi- toneal injection. S, sinusoid; E, endosteum; MK, megakaryocyte. Scale bar: 0.1 mm. (I) Quantification of megakaryocytes in the bone-associated region (within 100 μm of the endosteal surface within the diaphysis) by immunohistochemistry (WT mice, n=27; ITP mice, n=27; ITP mice treated with ATRA 5 mg/kg intraperitoneal injection, n=15; ITP mice treated with ATRA 20 mg/kg intraperitoneal injection, n=21). (Continued from previous page). (J) Quantification of megakaryocytes phys- ically associated with sinusoids (between 0-10 μm from the sinusoidal endothelium within the diaphysis) by immunohistochemistry (WT mice, n=27; ITP mice, n=27; ITP mice treated with ATRA 5 mg/kg intraperitoneal injection, n=15; ITP mice treated with ATRA 20 mg/kg intraperitoneal injection, n=21). (K) Quantification of the vascular area within marrow vessels by immunohistochemistry (WT mice, n=27; ITP mice, n=27; ITP mice treated with ATRA 5 mg/kg intraperitoneal injection, n=15; ITP mice treated with ATRA 20 mg/kg intraperitoneal injection, n = 21). (I-K) Tukey tests.
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