Influence of hyaluronic acid on wound healing using composite porcine acellular dermal matrix grafts and autologous skin in rabbits.

This study aims to explore the influence of hyaluronic acid (HA) on wound healing during xenogeneic porcine acellular dermal matrix (PADM) composite skin grafting. The results will facilitate the development of methods for improving graft contracture and poor elasticity of composite transplantation. Exogenous HA was added to composite PADM grafts and to thin autologous skin grafts during rabbit full-thickness skin wound repair. The influence of HA on wound healing was evaluated according to its contracture rate and its expression of collagen types I and III. The possible mechanism was then explored based on HA metabolism and vascularisation in the skin graft. The results show that exogenous HA relieves graft contracture on rabbit wound surfaces, increases collagen I and III expression and decreases the ratio between collagen types. HA stimulates the generation of more CD44 receptors to strengthen its enzymolysis. The resulting metabolites promote the vascularisation of the wound surface, which are conducive for mitigating graft contracture, and further improve the composite grafting effect.

[Mandibular-driven simultaneous maxillo-mandibular distraction for hemifacial microsomia with rapid prototyping technology].

OBJECTIVE: To explore the clinical application of mandibular-driven simultaneous maxillo-mandihular distraction to correct hemifacial microsomia with rapid prototyping technology. METHODS: The patient' s skull resin model was manufactured with rapid prototyping technology. The osteotomy was designed on skull resin model. According to the preoperative design, the patients underwent Le Fort I osteotomy and mandibular ramus osteotomy. The internal mandible distractor was embedded onto the osteotomy position. The occlusal titanium pin was implanted. Distraction were carried out by mandibular-driven simultaneous maxillo-mandihular distraction 5 days after operation. RESULTS: The distraction in five patients was complete as designed. No infection and dysosteogenesis happened. The longest distance of distraction was 28 mm, and the shortest distance was 16 mm. The facial asymmetry deformity was significantly improved at the end of distraction. The ocelusal plane of patients obviously improved. CONCLUSIONS: Rapid prototyping technology is helpful to design precisely osteotomy before operation. Mandibular-driven simultaneous maxillo-mandibular distraction can correct hemifacial microsomia. It is worth to clinical application.

[Effects of hyaluronic acid on biomechanic performance of porcine acellular dermal matrix plus thin skin autograft after transplantation].

OBJECTIVE: To explore the effects of hyaluronic acid (HA) on biomechanical properties for porcine acellular dermal matrix (PADM) plus thin skin autograft after transplantation. METHODS: The dorsa of 10 Japanese white rabbits were symmetrically divided into four areas of A-D by random grouping. Full-thickness skin defects were created in Groups A-C while Group D was blank with normal skin. Operations were performed in Group A: implant with HA + PADM + thin skin autografts, Group B: implant with PADM + thin skin autografts and Group C: skin autografts group. Histological examination of specimen was performed at Day 56 postoperatively. And the biomechanical properties such as relaxation and stress-strain properties of grafts were recorded. RESULTS: The structure of PADM was found to be basically intact by hematoxylin and eosin E dyeing in Groups A and B. In Group A, dense fiber structure could be observed. Lots of regularly arranged collagenous fibers and new blood capillaries were grown into the dermal matrix with sparsely distributed inflammatory cells. In Group B, acellular dermal matrix became clustered with a small amount of invaded fibroblasts. And there was a high expression of inflammatory cells. The biomechanic performances of transplanted skin were: Group A's curve was mostly close to that of Group D's, Group B's curve was the most further from that of Group D's (P = 0.001) and Group C's curve stayed between Groups A and B. Under the same strain, the stress of Groups A-D was (87 ± 8), (115 ± 9), (63 ± 7) and (81 ± 4) kPa respectively. No significant difference of stress existed between these two groups (P = 0.838). There was significant difference of stress between Groups B/C and D (P = 0.001 and P = 0.009). CONCLUSION: Topical hyaluronic acid may be used to enhance the biomechanics performances of transplanted skin.

[Experimental study of hyaluronic acid on the biomechanical compliance of porcine acellular dermal transplantation].

OBJECTIVE: To explore the effect on biomechanical compliance after an addition of hyaluronic acid (HA) in transplantation of porcine acellular dermal matrix (PADM) with skin autograft. METHODS: Ten Japanese white rabbits were used as experimental animal, the dorsa of rabbits was symmetrically divided into four area, and then grouping was randomized. Full-thickness skin defects were created in Group A to Group C, and Group D was blank group with normal skin. The following procedures were performed: Group A: implanted with HA+PADM+ thin skin autografts, GroupB: implanted with PADM+ thin skin autografts and Group C: skin autografts, except for Group D. The wound tissue specimens were harvested at 70 days postoperatively, and they were recorded contracture rates of the grafts and the biomechanical compliance by Instron biomechanics tensiometer. The expression of collagens I and III in dermal fibroblasts of each group was determined by Western blot. RESULTS: On postoperation day 70, the grafts contracture rates in Group A to Group C were 10.2% ± 0.6%, 36.6% ± 0.8%, 32.7% ± 1.4% respectively, there were notable significant difference among three groups (P = 0.000). Under the same tension, there was no significant difference in strain between Groups A and D ((83 ± 8) vs (81 ± 5) kPa, P = 0.552). Some significant difference in strain existed between Groups B and D ((215 ± 9) vs (81 ± 5) kPa, P = 0.000). The strain of Group C ((106 ± 7) kPa) was between Groups B and D, and significant strain difference existed among them (P = 0.000). The expressions of collagens I and III in Group A were higher than those in Group B, while the ratio of collagens I to III in Group A was lower than that in Group B. CONCLUSION: Topical HA may be used to increase the expressions of type I and III collagen, decrease the ratio of collagen type I/III, and enhance the biomechanics performances of transplanted skin.

[Effect of different concentration of tamoxifen ointment on the expression of TGF-beta2 of hypertrophic scar at rabbit ears].

OBJECTIVE: To observe the effect of different concentration of Tamoxifen ointment on the fibroblasts and transforming growth factor (TGF-beta2) of hypertrophic scar at rabbit ears, so as to explore the possibility of treatment of hypertrophic scar with Tamoxifen. METHODS: The hypertrophic scar model was established in 96 New Zealand rabbits' ears. The wounds were divided into four groups (A, B, C and D), with 144 wounds in each group. Different concentration of tamoxifen ointment (0.5%, 1%, 2%) was topically administered in groups A, B and C respectively, and blank ointment in group D. On postoperative day 30, 60 and 90, the scar samples were harvested. The scar thickness, scar histological change and the content of TGF-beta2 were detected. RESULTS: (1) On the 30th day after operation, the difference of scar tissue thickness among groups A, D and B, C reached statistical significance (group A, D < group B < group C). However, there was a contrary tendency in fibroblasts density and TGF-beta2 content of the scar tissue simultaneously. (2) On 60th, 90th day after injury, there was statistical difference in scar thickness, fibroblasts density and the content of TGF-beta2 in scar of four groups (P < 0.05). The content of TGF-beta2 in group A, B, C, D was (43.97 +/- 3.63) microg/L, (41.92 +/- 3.91) microg/L, (36.69 +/- 4.15) microg/L, (54.90 +/- 4.71) microg/L, respectively, on 60th day; and (45.69 +/- 2.63) microg/L, (40.43 +/- 3.87) microg/L, (38.76 +/- 3.24) microg/L, (52.59 +/- 4.92) microg/L, respectively, on 90th day. The fibroblasts density of scar in groups A, B, C, D was (4392.07 +/- 327.84) point/mm2, (4208.57 +/- 329.76) point/mm2 (4 033.44 +/- 427.91) point/mm2, (4863.03 +/- 387.98) point/mm2, respectively, on 60th day; and (4418.41 +/- 432.52) point/mm2, (4077.65 +/- 386.70) point/mm2, (3844.53 +/- 354.29) point/mm2, (4838.64 +/- 390.52) point/mm2, respectively, on 90th day. The content of TGF-beta2 and fibroblasts density of scar were lined up as group D > group A > group B > group C (P < 0.05). CONCLUSIONS: Topical Tamoxifen can reduce the content of TGF-beta2 and fibroblast, decrease fibroblasts density and the formation of hypertrophic scar at rabbit ears. It offers a new way for the treatment of the hypertrophic scar.

[Effects on collagen I and III after transplantation of porcine acellular dermal matrix with hyaluronic acid].

OBJECTIVE: To investigate the changes of collagens I and III after the addition of hyaluronic acid in the transplantation of porcine acellular dermal matrix. METHODS: Full-thickness skin defects were created on the dorsa of Japanese white rabbits. And the rabbits were divided randomly into 3 groups: Group A (hyaluronic acid, porcine acellular dermal matrix plus thin skin autografts), Group B (porcine acellular dermal matrix plus thin skin autografts) and Group C (skin autografts). Skin biopsies were performed at Day 50 post-grafting to detect the contents of collagens I and III by histological examinations, immunohistochemistry method and Western blot. RESULTS: The areas of skin graft were (13.3 ± 1.2), (9.5 ± 0.9) and (10.0 ± 1.4) cm(2) in Groups A, B and C respectively. Group A was larger than Groups B and C(all P < 0. 01). There was no statistical difference between Groups B and C (P > 0.05). The expressions of collagen I were 1894 ± 164, 515 ± 38 and 395 ± 43 in Groups A, B and C respectively. Group A was higher than Groups B and C (P < 0.01). And the expressions of collagen III were 5411 ± 435, 874 ± 70 and 2078 ± 175 in Groups A, B and C respectively. Group C was higher than Group B and yet lower than Group A (all P < 0.01). The ratios of collagen I and collagen III in Group A (0.39) and Group B (0.59) were higher than that of Group C (0.19) (all P < 0.01). CONCLUSION: The addition of hyaluronic acid may boost the expression of collagens I and III and decrease the ratio of collagen I/collagen III. Thus it facilitates wound healing and basilar membrane remodeling and alleviates the contraction of skin transplant.

[Effect of PRX-2 gene transferred by lipofectamine on the proliferation of human skin fibroblasts].

OBJECTIVE: To explore the effects of PRX-2 gene transferred by lipofectamine on the human skin fibroblasts. METHODS: Normal human skin fibroblasts were cultured and PRX-2 gene was transferred by lipofectamine. The proliferation of fibroblasts was detected by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide) and flow cytometry. RESULTS: The proliferation of PRX-2-transfected fibroblasts was stronger than that of normal counterparts. There were fewer cells during G0-G1 period and more cells during S and G2-M periods. The proliferative index increased. CONCLUSION: The proliferation of fibroblasts may be modified by transfected PRX-2. Thus PRX-2 plays an important role during the healing of human skin wound.

[An ultrastructure study on the palatomaxillary suture of dog expanded by NiTi-SMA].

OBJECTIVE: To explore the ultrastructure of the palate-maxillary sutures under tensile forces by transmission electron microscope (TEM). METHODS: The Suture expanders were made in NiTi-Shape memory alloy (NiTi-SMA). The maximum force was 3.5 N. Fourteen 8-month old mongrel dogs were used in the study. They were divided into three groups, (1) experimental group, (2) control group, (3) sham group. In the experiment and control groups, an 8 mm wide cleft was made by surgery. The suture expanders were fixed onto the palatine bones of the experimental group. The dogs of the experimental group were executed after 3, 7, 14, 28, 56 days of suture expansion. The change of suture tissue was examined by TEM. RESULTS: The cleft of the experiment group were closed at the ninth day of expansion. At the beginning, tissue rupture, exudation, death of fibroblasts, disruption of collagen and tear vessels were seen at the early stage of suture expansion. Then highly active functional manifestations were seen in both osteocytic and fibrocytic populations. At last, normal structure restored. CONCLUSIONS: Cell types and functional condition could be distinguished clearly by TEM. It suggests that the suture expansion should be the process of tissue repair and regeneration. The suture cells response, especially, the osteogenic response were the major factor of increasing suture width.

[Application of thoracic skin flap with multiple blood supply in repair of tissue defects and deformities in jaw and neck].

OBJECTIVE: To explore an appropriate measure to repair tissue defects and deformities in mandibulo-cervical region. METHODS: Eighteen cases with severe tissue defects and deformity in jaw and neck were repaired with thoracic skin flap with multiple blood supply system in our unit from Jan. 2006 to Nov. 2008. Anterior cutaneous branch of transverse cervical artery, intercostal branch of internal thoracic artery and lateral thoracic artery were included in the pedicles. RESULTS: All skin flaps survived, except in one patient in whom a small belb appeared at the distal end of the island flap with anterior cutaneous branch of transverse cervical artery, and it was healed after a few dressing changes. The functions and appearances were satisfactory after 6-month to 2-year follow-up, without showing secondary deformity. CONCLUSIONS: The blood supply of thoracic skin flap is abundant and constant, which is an ideal method for repair of tissue defects and deformities in jaw and neck after taking into account some factors, such as the demand of the patient, general physical condition, and the size of the defect.

Treatment strategies for mass burn casualties.

BACKGROUND: Mass burn casualties are always a great challenge to a medical team because a large number of seriously injured patients were sent in within a short time. Usually a high mortality is impending. Experiences gained from successful treatment of the victims may be useful in guiding the care of mass casualties in an armed conflict. METHODS: Thirty-five burn victims in a single batch, being transferred nonstop by air and highway from a distant province, were admitted 48 hours post-injury. All patients were male with a mean age of (22.4 +/- 8.7) years. The burn extent ranged from 4% to 75% ((13.6 +/- 12.9)%) total body surface area. Among them, thirty-two patients were complicated by moderate and severe inhalation injury, and tracheostomy had been performed in 15 patients. Decompression incisions of burn eschar on extremities were done in 17 cases before transportation. All the thirty-five patients arrived at the destination smoothly via 4-hour airlift and road transportation. Among them, twenty-five patients were in critical condition. RESULTS: These thirty-five patients were evacuated 6 hours from the scene of the injury, and they were transferred to a local hospital for primary emergency care. The patients were in very poor condition when admitted to our hospital because of the severe injury with delayed and inadequate treatment. Examination of these patients at admission showed that one patient was suffering from sepsis and multiple organ dysfunction syndrome. Dysfunction of the heart, lung, liver, kidney, and coagulation were all found in the patients. Forty-eight operations were performed in the 23 patients during one month together with comprehensive treatment, and the function of various organs was ameliorated after appropriate treatment. All the 35 patients survived. CONCLUSIONS: A well-organized team consisting of several cooperative groups with specified duties is very important. As a whole, the treatment protocol should be individualized, basing on the extent of the injury and the care that the patient had received at the spot. During airlift, the stretchers should be arranged perpendicular to the longitudinal axis of the cabin. The treatment protocol in our hospital consisted mainly of prompt effective relief of all life-threatening complications, followed by early closure of burn wounds, appropriate use of anti-infection therapy, emphasis on nutritional support, correction of metabolic disorders, alleviation of immunosuppression, correction of coagulopathy, and effective support and protection of organ function.

[Repairing of lower eyelid ectropion with expanded flap].

OBJECTIVE: To investigate the effect of reconstruction of lower eyelid ectropion with expanded flap. METHODS: Fourty patients with lower eyelid ectropion were reconstructed using tissue expander. The volume of the smallest expander was 30 ml, and that of the biggest one was 150 ml. The expand time was from 2-months to 3-months, then advancement or transposition flaps were created and employed in the defected lesion where the scar was removed just in one operation. RESULTS: All patients have been followed up for 2-year with satisfactory results and no recurrences was appearance. CONCLUSIONS: Application of expander reasonable may get satisfactory result in reconstruction of lower eyelid ectropion. The incision in donor site is hidden and the symptom seldom recurs.

[Differential display of homeobox gene expressions in the normal, wounded human fetal and adult skins by DNA microarray].

OBJECTIVE: To explore the differential expression of homeobox genes in the normal, wounded human fetal and adult skins and its significance in fetal scarless healing. METHODS: Gene chips containing 14 000 human genes were used to investigate homeobox gene expressions of the normal, wounded human fetal and adult skins. RESULTS: There were significant differences between the expression of homeobox genes, especially for PRX-2, HOXB13, HOXB6 and HOXB7. CONCLUSIONS: The homeobox gene is in close relation to developmental biology. The different expressions and changes of homeobox genes in the normal, wounded human fetal and adult skin may be a primary cause of different wound healing between fetal and adult skin.

[The role of tyrosine phosphorylation proteins in procollagen gene expression of fibroblasts in wound healing].

OBJECTIVE: To investigate the role of adhesion between fibronectin and fibroblasts in wound healing as well as tyrosine phosphorylation proteins in procollagen mRNA expression. METHODS: The level of proalpha1 (I) mRNA and tyrosine phosphorylation protein were detected employing the techniques of RT-PCR and immunoblotting. After inhibition of tyrosine kinases, herbimycin A was added to the medium to block the pathway of tyrosine phosphorylation, the changes of procollagen mRNA and tyrosine phosphorylation proteins were further investigated. RESULTS: The adhesion between fibroblasts and fibronectin in wound healing not only induced the production of 98kd and 65kd tyrosine phosphorylation protein, but also enhanced obviously the expression of procollagen alpha1 (I) mRNA. When the pathway of tyrosine phosphorylation was blocked, the level of procollagen alpha1 (I) mRNA lowered remarkably, accompanied by the decrease of 98kd, 65kd tyrosine phosphorylation proteins. CONCLUSION: The adhesion between fibronectin and fibroblasts plays an important role in expression increase of procollagen mRNA during wound healing, in the process of which tyrosine phosphorylation is a key step.

[The treatment of deformity of axillary scar contracture after burns].

OBJECTIVE: To explore the best methods to repair the deformity of axillary scar contracture after burns. METHODS: Ninety cases in 78 patients with axillary scar contracture after burns from January 1998 to January 2002 were analyzed. According to the severity of the deformity and its influence on the function of the shoulder joint. 46 cases suffered from mild degree axillary scar contracture, 26 cases with moderate and 18 with severe degree. The deformities of axillary scar contracture were repaired by Z plasty (18 cases), five-flap plasty (14 cases), skin graft (23 cases), Z plasty and skin graft (14 cases), transfer of scapular skin flaps (5 cases), lateral throatic skin flaps (4 cases) and scar flaps (12 cases), respectively. Exopexy, anti-scar drug and functional exercises were applied postoperationally. RESULTS: All the flaps were survived with first intention, except for necrosis of the split skin graft occurring in 4 cases. The function and configuration in all the cases were satisfactory after 6 months to 4 years follow-up. CONCLUSION: Appropriate methods should be chosen to restore the function and configuration of the shoulder joint and improve patients' living condition according to the size, degree of the deformity of axillary scar contracture after burns.

[A comparative study of PDGF and EGF expression in skin wound healing between human fetal and adult].

OBJECTIVE: To explore the differences of PDGF and EGF expression in the wound healing between fatal and adult. METHODS: With the established animal model of fetal scarless healing and the adult samples, an immunohistochemical technique was used to evaluate the expression of PDGF and EGF in the normal adult skin, normal fetal skin, and the process of their wound healing. RESULTS: 1. The expression of the PDGF was not found in the fetal skin, but a mild amount of the PDGF was shown in the epidermis and the upper dermal layer 12 hours and 1 day after the wounding process. In the normal adult skin, expression of PDGF was shown in the dermal fibroblasts, macrophagocytes and blood capillaries, and a strong expression was presented during its wound healing process. 2. In the fetal skin, the expression of the EGF was seen in the epidermis, hair follicles, sebaceous glands and sweat glands, but there were no markedly changes during the wound healing. In the adult skin, a positive stain of the EGF was shown in the basal layer of the epidermis while the mild stain in hair follicles and sweat glands. The level of the expression became gradually decreasing with the time going in the wounded adult skin. CONCLUSION: The different expression of growth factors between fetal and adult skin in wound healing may be one of the important reasons that the fetal wound could produce scarless healing.

[Expression of basic fibroblast growth factor during wound healing of human fetal and adult skin and its significance].

OBJECTIVE: To explore the expression of basic fibroblast growth factor(bFGF) during the wound healing of human fetal and adult skin and its significance. METHODS: We established the animal model of fetal scarless healing by transplanting full-thickness skin grafts from human fetus to a subcutaneous location on the athymic mouse recipient, and then making the linear incisions. The expression of bFGF was observed in the normal adult skin, normal fetal skin and during wound healing by immunohistochemical method. The positive staining cells were counted under selected high-power focus randomly. RESULTS: bFGF staining was not observed in the normal fetal skin and the wounded one. However, strongly positive staining was shown around the vessels in normal adult skin. Moreover, the positive straining became stronger in the wounded skin, especially in dermal fibroblasts and endotheliocytes. The number of positive staining cell was 2.1 +/- 0.1 in normal fetal skin, and 2.2 +/- 0.1, 2.1 +/- 0.3, 2.1 +/- 0.3 and 2.0 +/- 0.1 in the fetal skins after 12 hours, 1 day, 3 days and 7 days of wound respectively. The number of positive staining cell were 23.2 +/- 4.2 in normal adult skin and 40.5 +/- 3.6 in the wound adult skin. There was significant difference between the fetal skin and adult skin (P < 0.01). CONCLUSION: The negative expression of bFGF in the fetal skin may be one of the important reasons for fetal scarless healing.

[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. CONCLUSION: 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.

[The significance and the expression of homeobox genes during human burn wound healing].

OBJECTIVE: To investigate the expression of several homeobox genes during the wound healing in fetal and adult skin and their roles in fetal scarless wound healing. METHODS: The expressions of PRX-2, HOXB13, HOX2.2 and HOX2.3 during wound healing in fetal and adult skin were determined with in situ hybridization. RESULTS: (1) PRX-2 positive expression could be identified in normal fetal and adult skin, especially in the fetus. But there was difference in location sites of the genes. The positive expression in normal fetal skin was mainly found in the peripheral cells at the hair shafts within dermal papilla layers and was also found in the epithelium. Nevertheless, weak positive expression of PRX-2 was found in the epithelial basal layer cells in normal adult skin but not in dermal tissue. There was strong positive expression of the PRX-2 in the tissue around the wound in fetus but not of that in adults except the epithelial basal layers. (2) Positive expression of HOXB13 could be identified in both normal fetal and adult skins. And the expression was concentrated mainly in hair follicle cells in the dermis and in the basal layer cells in the epithelium. Furthermore, the expression became weak after trauma, especially in fetal skin. (3) The positive expression of HOX2.2 and HOX2.3 in normal fetal skin was observed mainly in the whole layer of the epithelium and especially in the epithelial basal layers. Weak positive expression could be found in the dermis and strong expression found in the tissue near the wound. But there was no positive expression of the HOX genes in normal adult skin and wounds. CONCLUSION: The difference in the HOX expression in fetal and adult skin wound healing might be the key factor leading to different wound healing. Homeobox genes might be closely related with the developmental biology.