1. Irina Kalashnikova, Junwang Xu, Carlos Zgheib, Soumen Das, Sudipta Seal, Kenneth W Liechty INTRODUCTION Diabetic wounds are characterized an acute inflammation during the wound healing response. Previous data indicated that Cerium Oxide Nanoparticles (CNPs) treatment can improve healing in skin wounds of mice. However, the mechanisms by CNPs improve wound repair is not clear. MicroRNAs (miR) is a small non- coding RNA regulating post-transcriptional gene expression. MiR-146a expression is down-regulated in diabetic wounds compared with non-diabetic wounds. CNPs CORRECT INFLAMMATORY RESPONSE IN DERMAL FIBROBLASTS HYPOTHESIS CNPs possess some features, particularly being able to diminish oxidative stress via ROS scavenging, may regulate expression of miRNA-146a in diabetic wounds accelerating healing (Fig. 1) FEATURES OF CNPs METHODS CNPs were synthesized using simple wet chemistry method and characterized by HR-TEM, XPS, UV-Vis, DLS, Zeta potential. Two models of wounds, in vitro and in vivo, were used. Primary dermal murine non-diabetic and diabetic fibroblasts were treated with 50-250ul of 10uM CNPs mixed with DMEM. 10-12-weeks old Db/Db and Db/+ mice underwent 8-mm full-thickness wounding. Postoperatively, the mice received 50ul of CNPs subcutaneous injection: 1) 10uM for both types of mice; 2) 25ug/ml for Db/+ and 40ug/ml for Db/Db mice; 3) 10uM for both types of mice and further daily topical application of 25ul of 10uM of NPs. RT-PCR analysis and histology using immunostaining F4/80 were used for inflammation evaluation. Fig. 7. 1. Slices of wound tissues stained with F4/80 antibodies, A-D: Db-CTL, Db- CNPs, Non-Db-CTL, Non-Db- CNPs; forming hair follicles in the diabetic (E) and non- diabetic (F) wound tissues treated with CNPs; 2. Correlation of macrophage cells number and miRNA- 146a expression in two groups of mice with wounds untreated (CTL) and treated with CNPs. CNPs CORRECT INFLAMMATORY RESPONSE IN THE WOUNDS Fig. 4. Effect of CNPs concentration on expression of miR-146a in fibroblasts (* p<0.05, ** p≤0.008, ᵻ p≤0.006) CNPs ACCELERATE WOUND HEALING CONCLUSIONS Fig. 8 The time-course of wound closure for three groups of mice, including control one, treated by CNPs in different dose (*p<0.05) Fig. 6. (A) miRNA-146a (*p<0.009, **p=0.0002, ***p=0.0001) and (B) genes expression levels (p 0.045÷2*10 - 4 ) for mice non-treated (CTL) and treated with single injection at day 0 and/or single injection at day 0 with topical daily application of 10uM CNPs. Recent work has contributed to better understanding of the mechanism of anti-inflammatory effect of nanoceria on diabetic wounds. High dose of CNPs as a treatment of the wounds accelerated wound closure, 3 and 2 days earlier wound closure for non-diabetic and diabetic mice, respectively than for ones in the control groups. CNPs increase miR-146a expression level and down-regulated expression level of NF-kB-relevant genes CNPs regulate the recruitment of appropriate number of macrophage cells via miR-146a expression correcting and improve wound structure, initiating hair follicle formation in both types of wounds. Fig.1 Schematic presentation of CNPs mechanism of diabetic wound healing acceleration Fig.2 Characteristics of CNPs obtained by HR-TEM, Zeta potential, DLS. Fig. 3. Scheme of defective immune response in diabetic wounds leading to chronic inflammation Fig. 5. miR-146a as a negative regulator NF-kB 1. 2. CNPs enhance wound healing