Burn Wound Healing Abilities of a Uronic Acid Containing Exopolysaccharide Produced by the Marine Bacterium Halomonas malpeensis YU-PRIM-29.

Bacterial exopolysaccharides (EPS) are an emerging class of biopolymers with extensive applications in different fields due to their versatile physico-chemical and biological properties. The role of EPS in healing of different wound types is gaining interest in the tissue engineering sector. Burn is one of the devitalizing injuries that causes greater physical harm and can be fatal. Appropriate treatment modalities have to be followed for faster healing outcomes and to minimize the risk. In this study, a bacterial EPS (EPS-H29) from the marine bacterium Halomonas malpeensis YU-PRIM-29 was used to treat the burn wound in vivo. The biochemical and structural characterizations of EPS-H29 were carried out using standard methods. In addition, FE-SEM, conformational, rheological, and HP-GPC analyses were carried out. In vitro biocompatibility of EPS-H29 was studied in human dermal fibroblasts (HDFs) and keratinocytes (HaCaT). Scratch assay was used to study the wound healing in vitro. For in vivo evaluation, burn wound (second-degree) was created on Wistar albino rats and treated with EPS-H29 along with appropriate control groups. The total sugar and protein contents of EPS-H29 were 72.0 ± 1.4% and 4.0 ± 0.5%, respectively, with a molecular weight of 5.2 × 10 Da. The lyophilized samples exhibited porous surface features, and in solution, it showed triple helical conformation and shear thickening behavior. In vitro cell-based assays showed biocompatibility of EPS-H29 up to 200 μg/mL concentration. At a concentration up to 50 μg/mL, EPS-H29 promoted cell proliferation. Significant increase in the HDF cell migration was evident with EPS-H29 (15 μg/mL) treatment in vitro and induced significantly higher (p ≤ 0.0001) closure of the scratch area (90.3 ± 1.1%), compared to the control (84.3 ± 1.3%) at 24 h. Enhanced expression of Ki-67 was associated with the cell proliferative activities of EPS-H29. The animals treated with EPS-H29 showed improved healing of burn wounds with significantly higher wound contraction rate (80.6 ± 9.4%) compared to the positive control (54.6 ± 8.0%) and untreated group (49.2 ± 3.7%) with histopathological evidence of epidermal tissue formation at 15 days of treatment. These results demonstrate the biocompatibility and burn wound healing capability of EPS-H29 and its potential as an effective topical agent for the burn wound care.