[Expression of hyaluronic acid and its receptor in the process of wound healing in different skin tissues and its significance].
OBJECTIVE
To explore the expression of hyaluronic acid (HA) and its receptor, Cluster of differentiation 44 (CD44) in proliferative scar and in the process of wound healing of normal human adult skin and fetal skin, and the effect of HA and its receptor on the process of human fetal skin scarless healing.


METHODS
An incision and then a hypodermic cavity were made on each side of the dorsal median line of 32 female adult BALB/c rats. Skin grafts from 8 human fetuses delivered by natural abortion, full-thickness skin grafts from 8 normal adults undergoing plastic operation, skin wound sample from the donor sites in legs of 8 patients undergoing dermatoplasty with intermediate split thickness skin graft, and proliferative scar from 8 patients of plastic surgery, non-adult and adult, were grafted into the hypodermic cavities. The levels of HA and its receptor were examined by radioimmunoassay, immunohistochemistry and flow cytometry.


RESULTS
The level of HA in normal fetal skin was 143 micro g/g +/- 10 micro g/g, 283 micro g/g +/- 12 micro g/g 12 hours after injury, 315 micro g/g +/- 12 micro g/g one days after injury, reached the peak (321 micro g/g +/- 12 micro g/g) 3 days after injury, and then decrease, became 319 micro g/g +/- 11 micro g/g one week after injury (P > 0.05 in comparison with that 3 days after injury). The level of HA in normal fetal skin was 143 micro g/g +/- 10 micro g/g, significantly higher than that in normal adult skin (51 micro g/g +/- 4 micro g/g), skin wound of normal adult (92 micro g/g +/- 6 micro g/g), and proliferative scar (72 micro g/g +/- 5 micro g/g, all P < 0.01). The level of HA in wounded adult skin was significantly higher than that in the proliferative scar, and even much higher than that in normal skin (P < 0.01). The level of CD44 in normal fetal skin was significantly higher than that in proliferative scar and adult skin (all P < 0.01). The level of CD44 in wounded fetal skin 24 hours after injury decreased, significantly lower than that in normal fetal skin. There was no statistically significant difference between the level of CD44 in fetal skin one week after injury and that 24 hours after injury (P > 0.05). The level of CD44 in wounded adult skin was significantly higher than that in the normal adult skin (P < 0.01). The level of CD44 in the proliferative scar was between the level of CD44 in normal adult skin and that in wounded adult one. In normal fetal skin, CD44, positively stained at a moderate level, was distributed in keratinized cells, basic cells of hair follicle, and fibroblast of dermis. After injury, staining of CD44 became milder, especially by the incision. Immunohistochemistry showed that in normal adult skin, CD44 was distributed mainly in fibroblast of dermis and basic cells of hair follicle, weakly positively stained. After injury, the staning became stronger.


CONCLUSIONS
The expression of HA and its receptor during the process of wound healing in human fetal skin is different from that in proliferative scars and adult skin, which might be one of the important causes of scarless healing of wounded fatal skin.
Song
Hui-feng
HF
Department of Burns and Plastic Surgery, 304th Hospital of Chinese People's Liberation Army, Beijing 100037, China.
Chai
Jia-ke
JK
Lin
Zi-hao
ZH
Liu
Ning-fei
NF
Chen
Min-liang
ML
Zhao
Yao-zhong
YZ
Chen
Bao-ju
BJ
Sheng
Zhi-yong
ZY
D000818:Animals; D002921:Cicatrix / Q000378:metabolism; D005260:Female; D005333:Fetus / Q000737:chemistry; D006801:Humans; D018960:Hyaluronan Receptors / Q000032:analysis*; D006820:Hyaluronic Acid / Q000032:analysis*; D051379:Mice; D008807:Mice, Inbred BALB C; D012867:Skin / Q000737:chemistry*; D014945:Wound Healing / Q000502:physiology*
D018960:Hyaluronan Receptors; D006820:Hyaluronic Acid