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.

[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.

[Construction of tissue-engineering skin with carrier of active composite dermal matrix].

OBJECTIVE: To construct of tissue engineering skin including active composite dermal matrix. METHODS: The human fibroblasts and bovine collagen with type I were inoculated on the surface of porcine acellular dermal matrix (PADM) for construction of active dermal substitute, then epidermal cells were inoculated on the dermal matrix for gas-liquid interface culture. The tissue-engineering skin was observed by histological examinations. RESULTS: The structure of fibroblasts in collagen was intact, which was used to construct composite dermal matrix with PADM. The epithelial structure of tissue-engineering skin was similar to that of normal skin with good cell differentiation. Some phenomena were showed in epidermis: basic layer, stratum spinosum, granular layer and stratum corneum, desmosomes. CONCLUSION: Fibroblasts-Collagen-PADM can be an optimal dermal matrix for construction of tissue-engineering skin.

[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.

[Application of carbon fiber dressing on burn wounds].

OBJECTIVE: To observe the effects of carbon fiber dressing on burn wounds. METHODS: Two hundreds and seventy seven burn patients were randomly divided into treatment group (group T) and control group (group C). The burn wounds were covered with carbon fiber dressing in T group, and with povidone iodine gauze in C group, respectively. The absorption capability of the dressing, inflammatory reaction and bacteria quantitation of wound tissues and wound healing time were observed, and biopsy of wounds were performed. RESULTS: The absorption capability of the dressing was higher, the wound inflammatory reaction was milder, and bacteria quantitation of wound tissues was lower in the group T than that in group C. The wound healing time in the group T was shorter than that in group C. CONCLUSIONS: Carbon fiber dressing is a new model dressing, it can absorb wound exudation, lessen inflammatory reaction and improve wound healing.

[Acellular porcine dermal matrix produced with different methods and an experimental study on its transplantation to skin wound].

OBJECTIVE: To observed the effect of healing quality of composite skin grafting consisting of acellular porcine dermal matrix combined with autologous split-thickness skin graft. METHODS: Porcine skin was treated with dispase II/triton X-100 or hyperosmotic saline/sodium-dodecyl-sulfate (SDS) respectively, and acellular porcine dermal matrix I (APDMI) and APDM II were obtained. Sixty-three Sprague-Dawley rats with full-thickness skin defects on the back were separately covered with APDMT + split-thickness autologous skin, or APDM II + split-thickness autologous skin. The quality of wound healing was observed, the rates of survival and contraction of the grafts were calculated, the tissue samples were harvested for histological examination, and compared with that of autologous split-thickness skin graft. RESULTS: The wound healing quality of composite skin I, and II was good. There was no significant difference in the rate of survival and contraction of the grafts between the two composite skin grafting groups. It was indicated by histological examination intact basal membrane. There was no significant difference in the survival rate between composite skin grafting groups and autologous split-thickness skin at the 6 th week after operation, but the contraction rates of the grafts in the composite skin groups were lower. CONCLUSION: Full-thickness skin defect can be healed by covering with acellular porcine dermal matrix produced by two methods combined with split-thickness autograft, and it can help improve the quality of wound healing.

[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.