| Objective: To develop the hyaluronic acid (HA) film, to discuss the mechanism and to observe the effect of the external using film on the wound healing of rats. To provide an experimental basis for clinical application. Methods: 1.Preparation of the external using film made from HA: Under the asepsis condition, the external using film of HA was completed. 2.Forty-eight male SD rats were randomly divided into 8 groups. Meanwhile, the experiment was designed self-contrast, the left of rat was used as treatment group and the right of rat was used as control group. Under general anesthesia, two 5cm cuts were made on two sides, parallel to the spine with the deep from epidermis to the muscle layer. Then the cut was sewn with 3~0 suture. The cut of treatment group was applied with HA film and then bound up with sterile gauze; and the control applied with NS gauze and then bound up also with sterile gauze. On the 1st, 3rd, 5th, 7th, 9th, 14th, 21st and 28th days after the surgery, 6 rats were killed to be collected to specimens. Under light microscope (LM) and transmission election microscope (TEM), the histologic change was observed and the content of HA was determined.Results: 1.General observation: After surgery, in the treatment group, the wound was clean, with little seepage on the surface of the wound, slight inflammation, no obvious red and swollen around the cut, and the healing line in the treat group was not clear. In the control group, there were escharosis on the surface of the wound, much more seepage, the wound was hard to clean, red and swollen around the cut and there was an obvious healing line after the wound healing. 2.Observation under LM: After surgery, compared with the control group, there was few inflammatory cells infiltrated on both sides of the derma incision; the proliferation of acanthoid cell layer was not obvious; the FBs with a bit small body and slim nucleus spread loosely; quite few new collagen fibers could be seen on both sides of the cut, with comparably small bunches of loosely spread collagen, and they were slight keratinized. 3.Observation under TEM: After surgery, compared with the control group, there was a slight degeneration in the FBs of the treatment group, with round or ovate nucleus, and rich chromatin gathered high electron density clots. The epidermic cells were big, with few loosely linked intercellular bridges. 4.The numbers of FBs: On the 3rd and 5th day, there were more FBs in the treatment group than those in the control group (P<0.05), and there was no significant difference between the two groups at different time (P>0.05). The numbers of inflammatory cells: There were more inflammatory cells inthe control group than those in the treatment group (P<0.05). 5.HA content: On the 1st day after the surgery the content of HA in both groups was no statistical difference (P>0.05). On the 3rd, 5th, the HA content was higher in treatment group than that in the control group (P<0.05), and there was no significant difference between the two groups at different time(P>0.05). In the treatment group there was no significant difference of HA content on the 1st and 3rd(P>0.05), on the 3rd day, the content of HA in control group began to drop down (P<0.05).Conclusions: 1.The external using film of HA was made in this study. 2. The external using film made from high molecular weight HA could repress the formation of scar, for HA could infiltrate into dermis. 3.HA external using film had powerful infiltrating activity at early stage of wound healing. With the healing of the epidermis layer, the infiltrating activity of HA began to decrease.4.The inflammation after wound could be inhibited by HA film. 5.During the healing, the HA film could influence the synthesis and deposition of collagen by affect FB. 6.HA could accelerate the healing of epidermis while delayed the formation of keratinization layer.
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