| Soft tissue augmentation is one of the most used therapeutic methods in the plastic surgery. Exploring the ideal soft-tissue filling material has greatly clinical significance. Using self-tissues not only has shortcomings of finite donor tissue , but also have to destroy normal tissue. Allotransplant and xenotransplant were limited to use for the immunologic rejection. Artificial materials are expensive or with poor biocompatability. For a long time ,the researches have been focused in exploring an idle filling material. Acellular dermal matrix (ADM) was first reported in 1995, which was a nature material treated by artificial methods. This material only remain dermis matrix so it could low immunologic rejection. Allogenic acellular dermal matrix have been used in treating full-thickness burns and soft tissue augmentation. It was proved that ADM was safe and effective, but the high price limited the using. Xenogeneic ADM can be easily gotten, so it is cheap. There have been some reports in management of full-thickness burns, but we haven't found any reports about xenogeneic ADM as filling material.The propose of studies is preliminary assessing of xenogeneic acelluar dermal matrix as soft tissue substitute. The porcine ADM had been made into two forms: the xenogeneic ADM in sheet and particulate ADM. We have studied the two forms used as filling material. This research contained: (1) evaluation of cytotoxicity in vitro; (2) studies on xenogeneic ADM implanted into hypoderm of rabbits; (3) studies on particulate ADM as injectable material. (4) clinical observation.Methods: 1. The effects of different concentration of xenogeneic ADM dipping liquid on L-929 were detected by MTT. 2. The xenogeneic ADM in sheet were implanted into the hypoderm of rabbits after folded into cubes (1.5x1x0.5cm3). The control groups were self-dermis and porcine dermis. The implants were periodic measured and observed with pathological and transmission electron microscopic technique.The mixtures of particulate ADM were injected into the back of ears.3. The augmentations were periodic measured and observed with pathological technique.4. 6 patients who had suffered from depressed deformity of soft tissue were selected to accept operations. 2 cases were treated with xenogeneic ADM in sheet, the other were particulat ADM.Results :1. Cytotoxicity examinations showed there were no significance between the experimental group and blank control group in cellproliferation. It was proved that the ADM were no apparent cytotoxity. 2. Observations demonstrated there were no cells found in the xenogeneic ADM before implantation. This material is the same as human soft tissue in character, so it is suitable for soft tissue augmentation. 3. After implantation, there were slight inflammatory reaction in xenogeneic ADM and self-dermis until 4 weeks. The degree of inflammatory reaction was greatly lower than porcine dermis implants. 4. Fibroblasts were found in the xenogeneic ADM 1 week after implantation . The number of fibroblasts in ADM were more than the self-dermis implants in 2-4 weeks. At 2 weeks there were blood capillary in the ADM implants, so it became an activity tissue. The absorptivity of ADM (28.2%) was lower than the self-dermis (39.4%).5. After injection, histological examinations showed the material had no degeneration . The absorptivity was 26.93% at 48 weeks.6. Clinical observation suggested the most cases had satisfactory results. No infection, displacement, deformation and stiffness were found in all cases. Conclusion: It is possible that xenogeneic ADM for soft tissue augmentation because ADM has good biocompatability, low absorptivity and no cytotoxicity. |
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