In vitro and in vivo toxicological studies of ingested nanocellulose, which has many potential food applications, revealed minimal toxicity.

This study suggested a feasible non-animal model for microsurgical training process for beginners and intermediate trainees.

Purpose To evaluate the hyaluronic acid (HA) inflammatory reaction, fibroblasts, fibrosis and duration of effect in the dorsal region of tobacco-exposed rats. Methods Ten Wistar rats were divided into two groups: tobacco-exposed-group (TEG;n=5) and air-control-group (CG;n=5). The TEG animals were tobacco-exposed twice a day, 30-minutes/session, during 60 days. After this period, all animals received 0.1 mL HA subcutaneous injection in the dorsal area. The volume of HA was measured immediately after HA injection and weekly using a hand-caliper in nine weeks. After this period, all the animals were euthanized, and a specimen of was collected to evaluate inflammatory cells, fibroblasts, and fibrosis by HE. Results This study showed a higher inflammatory reaction in TEG than CG: inflammatory cell-count (CG: 1.07±0.9; TEG: 8.61±0.36, p<0.001); fibroblast count (CG: 2.92±0.17; TEG: 19.14±0.62, p<0.001), and fibrosis quantification (CG: 2.0; TEG: 3.75, p<0.001). The analysis of the HA volume in nine weeks in the dorsal region did not show a difference between groups (p=0.39). Conclusions This study suggested that the HA injection in the TEG caused an increase in inflammatory cell count, fibroblast, and fibrosis quantification when compared to the CG. There was no difference in the duration of effect of HA between the groups.