OBJECTIVETo observe the changes in the structure and cytocompatibility of porcine acellular dermal matrix, which was prepared with dermal reticular layer, treated with matrix metalloproteinase 7 (MMP-7), genipin, and vacuum freeze-drying.

METHODSFifty-four pieces of porcine dermal reticular layer, prepared with lateral abdominal skin were obtained from healthy large Yorkshire pig with mechanical method under sanitary condition, each 10.0 mm×5.0 mm in size and 0.5 - 0.6 mm in thickness. They were divided into normal control group (A(1), without treatment, n = 6), decellularization group (B, decellularized, n = 12), decellularization + MMP-7 group (C, treated with MMP-7 after decellularization, n = 12), decellularization + MMP-7 + genipin group (D, treated with MMP-7 and genipin after decellularization, n = 12), and decellularization + MMP-7 + genipin + vacuum freeze-drying group (E, treated with MMP-7, genipin, and vacuum freeze-drying after decellularization, n = 12) according to the random number table. Meanwhile, 6 pieces of human acellular dermal matrix, with the same size and thickness as listed above, were taken as control group (A(2), without treatment) in the cytocompatibility tests. HE staining and scanning electron microscope were used to detect the cell number and the change in tissue structure in dermal scaffold in groups A(1) and B-E. Immunohistochemical staining was used to determine residual vimentin, laminin and collagen IV in groups A(1), B, and C. Cytotoxicity tests were employed to test the cytotoxicity of the leaching solutions of groups B-E. Human fibroblasts were seeded on the surface of dermal scaffold in groups A(2) and B-E. The proliferation of fibroblasts were determined on post culture day (PCD) 3, 7, and 14, and the content of IL-6 and IL-8 in the supernatant were determined on PCD 3 and 7 with enzyme-linked immunosorbent assay. Data were processed with two-way analysis of variance and LSD- t test.

RESULTSGranular structure with hair follicle in pale yellow color was observed in group A(1). Small amount of hair, epithelial root sheath, nuclei, cell debris-like structure, vimentin, laminin, and collagen IV were observed in group B but not in group C, D, or E, which had been treated with MMP-7. The toughness of dermal scaffold was stronger in groups D, E than in groups B and C as observed in gross condition observation. The collagen fibers of dermal scaffold in groups C-E maintained their structural integrity with similar arrange as that of group A(1). The interspaces among collagen fibers in groups C-E were all increased, while those of groups C and D were similar but larger than that in group B; the interspace in group E was the largest. Groups B-E scored level 0 or 1 in the cytotoxicity test. Fibroblasts could proliferate on the surface of dermal scaffold in groups A(2) and B-E. Furthermore, with the extension of culture time, fibroblasts gradually became to be stratified to form multiple layers, and they proliferated toward the dermis. High density of fibroblasts was observed on the surface in groups D and E and in the deep layer in groups A(2) and C. On PCD 7, the contents of IL-6 [(132 ± 14), (104 ± 9), (122 ± 14), (120 ± 12), (128 ± 17) pg/mL] and IL-8 [(135 ± 18), (102 ± 17), (127 ± 18), (134 ± 23), (141 ± 24) pg/mL] in the supernatant in groups A(2) and B-E were significantly higher than those on PCD 3 [(55 ± 13), (34 ± 8), (48 ± 8), (50 ± 13), (49 ± 12) pg/mL] and [(93 ± 19), (63 ± 11), (82 ± 15), (82 ± 16), (89 ± 16) pg/mL], with F values respectively 98.869, 184.038, 125.531, 93.237, 87.265 and 15.694, 23.451, 22.801, 19.607, 18.808, P values below 0.05. The differences among groups A(2) and B-E in the levels of IL-6 and IL-8 at each time point were statistically significant (with F values respectively 2.809, 3.301 and 3.757, 3.266, P values below 0.05). The differences among groups A(2), C, D, and E in amount of IL-6 and IL-8 at each time point were not statistically significant (with t values respectively 0.058 - 1.905 and 0.034 - 1.295, P values above 0.05), but they were all higher than those in group B (with t values respectively 3.707 - 5.612 and 2.785 - 4.079, P values below 0.05).

CONCLUSIONSThe low immunogenic porcine dermal scaffold treated with MMP-7, genipin, and vacuum freeze-drying after decellularization, has good cytocompatibility. The growth of only a few fibroblasts in the dermal scaffold may be correlated with genipin, which increases tissue toughness.

Acellular Dermis ; Animals ; Cells, Cultured ; Dermis ; transplantation ; Histocompatibility ; Humans ; Skin Transplantation ; Swine ; Tissue Scaffolds ; Wound Healing

OBJECTIVETo observe the experimental results and histopathological changes of acellular xenogenic dermal matrix (X-ADM) and allogeneic sclera used as wrapping materials of hydroxy apatite (HA) ocular implants in New Zealand white rabbits.

METHODSTwenty-four rabbits received unilateral eye enucleating and the sockets were implanted with HA spherical implants wrapped with either acellular xenogenic dermal matrix or allogeneic sclera at random. The rabbits were examined for inflammation and implant exposure and sacrificed at 1, 2, 4, 6, 8 and 12 weeks after implantation. The sockets with the grafts were exenterated and the specimens were assessed histopathologically and ultrastructurally with light or transmission electron microscopy for the changes in inflammation reaction and vascularization.

RESULTSCompared to allogeneic sclera at the same stage of implantation, acellular xenogenic dermal matrix demonstrated more active and earlier growth of fibroblasts and new vessels with abundant collagen deposition. There were few inflammatory cells and no rejection was found.

CONCLUSIONThis experiment showed that the acellular xenogenic dermal matrix, with fast neovascularization and low immunity, can be an ideal material of ocular implant and a good substitute for allogeneic sclera.

Animals ; Dermis ; transplantation ; Eye, Artificial ; Female ; Hydroxyapatites ; Male ; Rabbits ; Sclera ; transplantation ; Swine ; Transplantation, Heterologous ; Transplantation, Homologous

OBJECTIVETo compare the composite grafts of acellular dermal matrix (ADM) from different sources with autoskin.

METHODSSix local white mini pigs were employed for the experiment. The pigs were randomly divided into four groups according to different skin grafts, i.e. A (human ADM with razor thin autoskin), B (porcine ADM with razor thin autoskin), C (razor thin autoskin only), and D (split thickness autoskin) as control. The survival rate, the contraction degree of the grafts, and the histological changes in grafting area were observed at 2, 4, 8, 12 and 24 hours after the operation.

RESULTSThe grafted area in both A and B groups appeared smooth and elastic with satisfactory graft survival. The in growth of the host reparative cells such as fibroblast and vascular endothelium could be induced by composite grafts of different ADMs with skin grafting. The contraction areas in A and B groups seemed bigger than those in C and D groups. The tissue structure of grafting areas was similar to that of split thickness skin grafting area at 24 post-operation weeks.

CONCLUSIONCombination of the homogenous and heterogeneous ADMs with autografts exhibited similar biological function during the observation period (24 weeks after operation). Xenogenous ADMs might have broader clinical applications.

Animals ; Dermis ; transplantation ; Graft Survival ; Humans ; Skin Transplantation ; methods ; Swine ; Transplantation, Autologous ; Transplantation, Homologous

OBJECTIVETo evaluate the histocompatibility of homologous acellular dermal matrix as a wrapping material for a hydroxyapatite orbital implant and compare the speed of fibrovascular ingrowth in hydroxyapatite orbital implant wrapped with homologous acellular dermal matrix and homologous sclera respectively.

METHODSTwenty four New Zealand rabbits were divided into two groups randomly. One group is implanted with hydroxyapatite orbital implant wrapped with homologous acellular dermal matrix behind the globe, the other group with homologous sclera. The observation included immunological reaction of the globe postoperation. Biopsies of implanted material were taken on weeks 1, 4, 8 and 12 postoperation for histopathological and electron microscope examination.

RESULTSHistological examination showed the homologous acellular dermal matrix has no immunological and inflammatory reaction after implanted in orbit. But the speed of fibrovascular ingrowth is a little slower than that of homologous sclera.

CONCLUSIONSThe homologous acellular dermal matrix has the better histocompatibility as an encapsulating biomaterial, it can be a new material instead of homologous sclera.

Animals ; Biocompatible Materials ; Dermis ; transplantation ; Female ; Male ; Orbital Implants ; Rabbits ; Sclera ; transplantation ; Transplantation, Homologous

OBJECTIVETo prepare a porcine acellular dermal matrix (PADM), and to optimize the interpore distance between PADM and co-grafted split-thickness autologous skin.

METHODSPorcine skin was treated with trypsin/Triton X-100 to prepare an acellular dermal matrix. Micropores were produced on the PADM with a laser punch. The distance between micropores varied as 0.8 mm, 1.0 mm, 1.2 mm and 1.5 mm. Full-thickness defect wounds were created on the back of 144 SD rats. The rats were randomly divided into 6 groups as follows, with 24 rats in each group. Micropore groups I -IV: the wounds were grafted with PADM with micropores in four different intervals respectively, and covered with split-thickness autologous skin graft. Mesh group: the wounds were grafted with meshed PADM and split-thickness autograft.

CONTROL GROUPwith simple split-thickness autografting. The gross observation of wound healing and histological observation were performed at 2, 4, 6 weeks after surgery. The wound healing rate and contraction rate were calculated.

RESULTSTwo and four weeks after surgery, the wound healing rate in micropore groups I and II was lower than that in control group (P < 0.05), but no obvious difference was between micropore groups I , II and mesh group (P > 0.05) until 6 weeks after grafting( P <0.05). The wound contraction rate in micropore groups I and II ([(16.0 +/- 2.6)%, (15.1 +/- 2.4)%] was remarkably lower than that in control group 4 and 6 weeks after grafting (P < 0.05), and it was significantly lower than that in mesh group [(19.3 +/- 2.4)%] 6 weeks after surgery (P <0.05). Histological examination showed good epithelization, regularly arranged collagenous fibers, and integral structure of basement membrane.

CONCLUSIONLaser micropore PADM (0.8 mm or 1.0 mm in distance) grafting in combination with split-thickness autografting can improve the quality of wound healing. PADM with laser micropores in 1.0 mm distance is the best choice among them.

Animals ; Dermis ; transplantation ; Lasers ; Rats ; Rats, Sprague-Dawley ; Skin Transplantation ; methods ; Skin, Artificial ; Swine ; Transplantation, Heterologous

OBJECTIVETo investigate the difference of the antigenicity of xenogenic acellular dermal matrix (ADM) implants prepared by different methods.

METHODSThe split-thickness skin sheet from swine was processed by trypsin and Triton X-100 to make xeno-ADM. Twenty-five Japanese white rabbits were divided into 5 groups, i.e. xeno-ADM(1) (conjugated with glutaraldehyde), xeno-ADM(2) (conjugated with network) and xeno-ADM(3) (no conjugation, as control), in which the ADMs were and xeno-ADM(4) (conjugated) and allo-ADM (no conjugated as control), in which the ADMs were embedded into the subcutaneous place of rabbit ear and back after that the rabbits were pre-sensitized by xeno-ADM soluble protein antigen injections. The titers of anti ADMs antibody in rabbit serum were monitored during 2 - 32 post-operative weeks and the histological changes of the embedded ADMs were observed grossly and microscopically.

RESULTSThe serum titers of anti-xeno-ADM in xeno-ADM(4) group was the highest. Whereas regardless of the sensitizing effects, the titers in all groups ranged as follows: xeno-ADM(3) > xeno-ADM(2) > xeno-ADM(1) (P < 0.05 - 0.01). About 40% serum samples in allo-ADM group exhibited positive anti-allo-ADM protein antibodies. Histologically, Evident and lasting inflammatory reaction could be found in the xeno-ADM grafting sites, which was much stronger than that in allo-ADM group. The degradation and absorption gradient of ADM was ranked as follow: xeno-ADM(3) > xeno-ADM(2) > xeno-ADM(4) > xeno-ADM(1) > Allo-ADM. Foreign body megalocytic reaction might evoke in the surrounding of conjugated ADM.

CONCLUSIONThe immunogenicity in xeno-ADM was stronger than that in allo-ADM, which could induce the host to develop immune reaction restricted by IgG. Large sheets of degenerated ADM implants could lower down the antigen-antibody reaction and ameliorate the structural destroying and degeneration absorption of ADM induced by inflammatory immune reaction.

Animals ; Antigen-Antibody Reactions ; Dermis ; immunology ; transplantation ; Male ; Rabbits ; Skin Transplantation ; Swine ; Transplantation, Heterologous

Artificial dermis is a kind of tissue engineering dermal substitute and is used to repair dermal defects caused by a variety of reasons. This article describes the characteristics and the mechanism of repair and reconstruction of bilayer artificial dermis. Based on domestic experience of clinical applications and relative literature of bilayer artificial dermis, more than 50 domestic experts in related field reached a consensus on indications, contraindications, operation procedures in clinical application, cautions, and treatment and prevention of complications of bilayer artificial dermis, providing reference for clinical application.
Consensus ; Dermis ; pathology ; Skin Transplantation ; methods ; Skin, Artificial ; Tissue Engineering

OBJECTIVETo investigate the immunologic reaction difference between xenogeneic and allogeneic acellular dermal matrix (ADM) grafting.

METHODSSplit thick skin samples harvested from healthy piglets and human volunteers who underwent losing-weight operation were processed to be xeno-ADM and allo-ADM. The ADMs overlapped with ultrathin auto-skin were employed to immediately cover the wound after escharectomy in deep burn patients. The patients were correspondingly set to be Xeno (26 cases) and Allo (10 cases) groups. Another 8 cases with deep burn wounds were grafted with only split thick autoskin (TTS) after escharectomy as control group. The tissue samples from grafted area were observed by immunohistochemistry after the grafting. The typing of immune cells in peripheral blood and grafted tissue was determined.

RESULTS(1) The CD4(+), CD45RO(+) and CD4(+)/CD8(+) cell ratios in peripheral blood in Xeno group increased slightly after the skin grafting when comparing to those in control group (P > 0.05). (2) There existed lasting inflammatory and immunological reaction in the local site of grafts in Xeno group. In addition, more than 80% of the inflammatory cells could be found to be CD3(+)/CD4(+), CD45RO(+). But CD8(+), Vs8C(+) plasmocytes and CD57(+) NK cells were found less. Furthermore, eosinophil and CD68(+)/CD4(+) foreign body megalocyte reactions could also be identified, especially in Xeno-ADM before rejection (P < 0.05 - 0.001). There was only mild inflammatory and immunological reaction during early grafting stage (within 8 post-operational weeks) in Allo-group.

CONCLUSIONThe specific immunologic reaction of human host to ADM might be participated by mononuclear cells and macrophages and presented mainly as cellular immune reaction induced by CD4(+) T lymphocytes. Furthermore, the foreign body megalocyte constructed by help T cell and macrophage might play important roles in the reaction.

Animals ; Burns ; immunology ; surgery ; Dermis ; transplantation ; Graft Rejection ; Humans ; Skin Transplantation ; immunology ; methods ; Swine ; Transplantation, Heterologous ; Transplantation, Homologous

In this study the treatment effect of combined implantation of autologous skin on pig dermis in injured rats was observed. Twenty-one Wistar rats were used, and the wounds were formed by excising a piece of full thickness skin on the back. After the pig dermis was implanted, the autologous skin was grafted on the dermis at 0.7 and 10 days. In the group with perforated pig dermis, the autograft skin was implanted on the day when the pig dermis was implanted. The healing effect was evaluated by measuring wound area, and by observing the growth of the autograft skin. Two weeks after the autograft skin was implanted, the skin securely adhered to the dermis, and the edge of autograft skin expanded clearly. The wound of the autograft skin implanted in the perforation of the dermis healed completely after 3 weeks, but the other 3 groups had remnant small wound. The autograft skin merged with the dermis and its surrounding tissue, but a clear dividing line still existed between autograft skin and dermis after implantation. The area of the implanted dermis and autograft skin varied from 51.8% to 65.9% compared to its original size. The results suggested that the time and the way of autologous skin grafting on xenogenous dermis may influence wound contraction and healing time.
Animals ; Dermis ; transplantation ; Female ; Graft Survival ; Male ; Rats ; Rats, Wistar ; Skin Transplantation ; methods ; Swine ; Swine, Miniature ; Transplantation, Autologous ; Transplantation, Heterologous

Biological Dressings ; Dermis ; cytology ; transplantation ; Extracellular Matrix ; transplantation ; Gingival Recession ; surgery ; Humans ; Mouth Diseases ; surgery