Control of hypertrophic scar from inception by using xenogenic (porcine) acellular dermal matrix (ADM) to cover deep second degree burn

The clinical outcomes of xenografts in the treatment of burn patients: a systematic review and meta-analysis

BACKGROUND

Although autografts are not feasible in patients with extensive burn wounds, allografts and xenografts can be used for temporary coverage. In this systematic review and meta-analysis, we compared the outcomes of xenografts and the standard treatment of burn wounds.

METHODS

International online databases were searched for English articles comparing xenografts with routine treatment in the burn patients. The random-effects model was used to estimate standardized mean differences (SMD) or odds ratios (OR) with a 95% confidence interval (CI).

RESULTS

From a total of 7144 records, 14 studies were included in our review after screening by title and abstracts followed by full-texts. No significant difference in hospital stays was found between the mammalian xenografts and control groups (SMD [95% CI] = - 0.18 [- 0.54-0.18]). The mean number of dressing changes was significantly lower in both mammalian xenografts compared to the controls (SMD [95% CI] = - 1.01 [- 1.61-- 0.41]) and fish xenografts compared to controls (SMD [95% CI] = - 6.16 [- 7.65-- 4.66]). In the fish xenografts, re-epithelialization time was significantly lower compared to controls (SMD [95% CI] = - 1.18 [- 2.23-- 0.14]).

CONCLUSIONS

Xenografts showed a significantly lower number of dressing changes and fish xenografts showed significant benefit in re-epithelialization compared to routine treatment. The beneficial results of xenografts suggest further research in the use of different types of xenografts in patients with extensive burn.

Porcine Acellular Dermal Matrix Promotes Migration and Suppresses Inflammation of Keratinocytes by Mediating the AKT Signaling Pathway

Porcine acellular dermal matrix (pADM) is known to accelerate wound healing. However, the underlying molecular mechanism remains unclear. This study aimed to investigate the effects of pADM on wound healing and its underlying mechanisms. HaCaT cells were treated with hydrogen peroxide (H2O2) or pADM, and the appropriate treatment concentration was determined using the cell counting kit-8 and flow cytometry. Cell migration was assessed using a Transwell assay and scratch test. Inflammation was evaluated using enzyme-linked immunosorbent assay. Western blotting was performed to measure the levels of protein kinase B (AKT) pathway-related proteins. The results showed that H2O2 inhibited cell viability and induced apoptosis in a dose-dependent manner. pADM promoted cell migration and decreased the levels of interleukin (IL)-6, IL-8, and tumor necrosis factor-α (TNF-α) in H2O2-treated HaCaT cells. Moreover, pADM rescued the downregulation of phosphorylated (p)-AKT and p-mechanistic target of rapamycin (mTOR) induced by H2O2. LY294002, a phosphatidylinositol 3-kinase (PI3K) inhibitor, abrogated migration and anti-inflammatory response caused by pADM. In conclusion, pADM promotes cell migration and inhibits inflammation by activating the AKT pathway under oxidative stress. These findings support the use of pADM for post-traumatic therapy and reveal a novel underlying mechanism of action.

Nonsurgical Management of Hypertrophic Scars: Evidence-Based Therapies, Standard Practices, and Emerging Methods

Hypertrophic scars, resulting from alterations in the normal processes of cutaneous wound healing, are characterized by proliferation of dermal tissue with excessive deposition of fibroblast-derived extracellular matrix proteins, especially collagen, over long periods, and by persistent inflammation and fibrosis. Hypertrophic scars are among the most common and frustrating problems after injury. As current aesthetic surgical techniques become more standardized and results more predictable, a fine scar may be the demarcating line between acceptable and unacceptable aesthetic results. However, hypertrophic scars remain notoriously difficult to eradicate because of the high recurrence rates and the incidence of side effects associated with available treatment methods. This review explores the various treatment methods for hypertrophic scarring described in the literature including evidence-based therapies, standard practices, and emerging methods, attempting to distinguish those with clearly proven efficiency from anecdotal reports about therapies of doubtful benefits while trying to differentiate between prophylactic measures and actual treatment methods. Unfortunately, the distinction between hypertrophic scar treatments and keloid treatments is not obvious in most reports, making it difficult to assess the efficacy of hypertrophic scar treatment.

Introduction of a New Surgical Method to Improve Bone Healing in a Large Bone Defect by Replacement of the Induced Membrane by a Human Decellularized Dermis Repopulated with Bone Marrow Mononuclear Cells in Rat

The Masquelet technique for the treatment of large bone defects is a two-stage procedure based on an induced membrane. We eliminate the first surgical step by using a decellularized dermal skin graft (Epiflex^®) populated with bone marrow mononuclear cells (BMC), as a replacement for the induced membrane. The aim of this study was to demonstrate the feasibility of this technology and provide evidence of equivalent bone healing in comparison to the induced membrane-technique. Therefore, 112 male Sprague–Dawley rats were allocated in six groups and received a 10 mm femoral defect. Defects were treated with either the induced membrane or decellularized dermis, with or without the addition of BMC. Defects were then filled with a scaffold (β-TCP), with or without BMC. After a healing time of eight weeks, femurs were taken for histological, radiological and biomechanical analysis. Defects treated with Epiflex^® showed increased mineralization and bone formation predominantly in the transplanted dermis surrounding the defect. No significant decrease of biomechanical properties was found. Vascularization of the defect could be enhanced by addition of BMC. Considering the dramatic reduction of a patient’s burden by the reduced surgical stress and shortened time of treatment, this technique could have a great impact on clinical practice.

A novel antibacterial acellular porcine dermal matrix cross-linked with oxidized chitosan oligosaccharide and modified by in situ synthesis of silver nanoparticles for wound healing applications

Not only are the physicochemical properties and biocompatibility of biomaterials important considerations, but also their antibacterial properties. In this study, a novel chemically-cross-linked antibacterial porcine acellular dermal matrix (pADM) scaffold was fabricated according to a two-step method. A naturally-derived oxidized chitosan oligosaccharide (OCOS) was used to cross-linked pADM (termed OCOS-pADM) to improve its physicochemical properties. Residual aldehyde groups within the OCOS-pADM were used in a redox reaction with Ag ions to produce Ag nanoparticles (AgNPs) in situ. As the AgNPs were tightly adhered onto the scaffold fibrils (termed OCOS-AgNPs-pADM), this effectively functionalized scaffold with antibacterial properties. The generated AgNPs were characterized by UV-Vis diffuse reflectance spectroscopy, XPS and SEM. The results of DSC, TG and enzymatic degradation demonstrated that OCOS-AgNPs-pADM possessed improved thermal stability and resistance to enzymatic degradation compared with pADM scaffolds. The kinetic experiment of the release of silver showed that silver was released in a controllable way. After introducing AgNPs into scaffolds, the OCOS-AgNPs-pADM possessed wide-spectrum antibacterial activity against Escherichia coli and Staphylococcus aureus. Furthermore, MTT assay and CLSM showed that the scaffolds had good biocompatibility. Pieces of OCOS-AgNPs-pADM were implanted into Sprague-Dawley rats to characterize their ability to repair full-thickness skin wounds. And results showed that the OCOS-AgNPs-pADM could accelerate the wound healing process. Overall, this work contributes new insight into the chemical cross-linking and functionalization of pADM scaffolds. In addition, as novel antibacterial scaffolds, OCOS-AgNPs-pADMs have the potential for development as wound dressing materials.

Effects of porcine acellular dermal matrix treatment on wound healing and scar formation: Role of Jag1 expression in epidermal stem cells

Skin wound healing involves Notch/Jagged1 signaling. However, little is known how Jag1 expression level in epidermal stem cells (ESCs) contributes to wound healing and scar formation. We applied multiple cellular and molecular techniques to examine how Jag1 expression in ESCs modulates ESCs differentiation to myofibroblasts (MFB) in vitro, interpret how Jag1 expression in ESCs is involved in wound healing and scar formation in mice, and evaluate the effects of porcine acellular dermal matrix (ADM) treatment on wound healing and scar formation. We found that Jag1, Notch1 and Hes1 expression was up-regulated in the wound tissue during the period of wound healing. Furthermore, Jag1 expression level in the ESCs was positively associated with the level of differentiation to MFB. ESC-specific knockout of Jag1 delayed wound healing and promoted scar formation in vivo. In addition, we reported that porcine ADM treatment after skin incision could accelerate wound closure and reduce scar formation in vivo. This effect was associated with decreased expression of MFB markers, including α-SMA Col-1 and Col-III in wound tissues. Finally, we confirmed that porcine ADM treatment could increase Jag1, Notch1 and Hesl expression in wound tissues. Taken together, our results suggested that ESC-specific Jag1 expression levels are critical for wound healing and scar formation, and porcine ADM treatment would be beneficial in promoting wound healing and preventing scar formation by enhancing Notch/Jagged1 signaling pathway in ESCs.

Even Better Than the Real Thing? Xenografting in Pediatric Patients with Scald Injury

This article reviews a single burn center experience with porcine xenografts to treat pediatric scald injuries, over a 10-year period. The authors compare xenografting to autografting, as well as wound care only, and provide outcome data on length of stay, incidence of health care-associated infections, and need for reconstructive surgery.

The Preparation of Acellular Dermal Matrices by Freeze-Thawing and Ultrasonication Process and the Evaluation of Its Antigenicity

Antigenicity is the biggest obstacle of xenogeneic acellular dermal matrices (ADM) as dermal scaffold in treatment of large-area skin defect. We prepared ADM by repeated freezing and thawing and ultrasonic process, and then injected the ADM homogenate and degradation product into porcine skin to evaluate the effectiveness of the decellularized method and the antigenicity of porcine ADM. In this work, chinese miniature pigs (n = 10) were sensitized by subcutaneous injection with human ADM degradation products on days 0, 7, and 14. After 21 days, their abdominal skin was divided into five regions for intradermal injection of porcine ADM homogenate (PADM), PADM degradation products, human ADM homogenate (HADM), HADM degradation products, and physiological saline (negative control). Positive controls (n = 2) were processed with fresh human skin homogenate by the same method. The skin manifestations in related areas were observed at 24 and 48 h and then the skin was subjected to histopathological and immunohistochemical analysis. The results showed that skin erythema and hydroderma were not observed in all groups but in positive control group. The histopathological and immunohistochemical results confirmed that no inflammatory cell infiltration, irregular extracellular matrix, IL-2, and IFN-γ expression were observed in all four test groups. Our results suggest that the combination with repeated freeze-thawing and ultrasonication can be an effective method to prepare ADM, which has great potential in clinical application.

Decellularized scaffolds in regenerative medicine

Allogeneic organ transplantation remains the ultimate solution for end-stage organ failure. Yet, the clinical application is limited by the shortage of donor organs and the need for lifelong immunosuppression, highlighting the importance of developing effective therapeutic strategies. In the field of regenerative medicine, various regenerative technologies have lately been developed using various biomaterials to address these limitations. Decellularized scaffolds, derived mainly from various non-autologous organs, have been proved a regenerative capability in vivo and in vitro and become an emerging treatment approach. However, this regenerative capability varies between scaffolds as a result of the diversity of anatomical structure and cellular composition of organs used for decellularization. Herein, recent advances in scaffolds based on organ regeneration in vivo and in vitro are highlighted along with aspects where further investigations and analyses are needed.

A novel dermal matrix generated from burned skin as a promising substitute for deep-degree burns therapy

The extensive skin defects induced by severe burns are dangerous and can be fatal. Currently, the most common therapy is tangential excision to remove the necrotic or denatured areas of skin, followed by skin grafting. Xenogeneic dermal substitutes, such as porcine acellular dermal matrix (ADM), are typically used to cover the burn wounds, and may accelerate wound healing. It is assumed that burned skin that still maintains partial biological activity may be recycled to construct an autologous acellular dermal matrix, termed 'deep‑degree burned dermal matrix (DDBDM)'. In theory, DDBDM may avoid the histoincompatibility issues associated with foreign or xenogeneic dermal matrices, and reduce therapy costs by making full use of discarded skin. In the present study, the collagens within prepared DDBDM were thickened, disorganized and partially fractured, however, they still maintained their reticular structure and tensile strength (P<0.01). Through microarray analysis of the cytokines present in ADM and DDBDM, it was determined that the DDBDM did not produce excessive levels of harmful burn toxins. Following 4 weeks of subcutaneous implantation, ADM and DDBDM were incompletely degraded and maintained good integrity. No significant inflammatory reaction or rejection were observed, which indicated that ADM and DDBDM have good histocompatibility. Therefore, DDBDM may be a useful material for the treatment of deep‑degree burns.

Use of porcine acellular dermal matrix following early dermabrasion reduces length of stay in extensive deep dermal burns

OBJECTIVE

Extensive deep partial-thickness burns still seriously challenge the surgeon's abilities. This study aimed to assess the impact of early dermabrasion combined with porcine acellular dermal matrix (ADM) in extensive deep dermal burns.

METHODS

From September 2009 to September 2013, a total of 60 adult patients sustained greater than 50% total body surface area (TBSA) burn by hot water or gas explosion were divided into three groups based on dermabrasion: group A (early dermabrasion and porcine ADM), group B (early dermabrasion and nano-silver dressings), and group C (conservative group). The wound healing time and length of hospital stay were analyzed. Scar assessment was performed at 3 and 12 months after the injury with a modified Vancouver Scar Scale linked with TBSA (mVSS-TBSA).

RESULTS

No significant difference was found in mean burn size, burn depth, age, male-to-female ratio, or incidence of inhalation injury between the patients in the three groups (p>0.05). Compared with groups B and C, the patients that received early dermabrasion combined with porcine ADM had a shorter wound healing time (p<0.01). The burn patients treated with early dermabrasion and porcine ADM coverage had a mean length of hospital stay of 28.3 days (±7.2), which was significantly shorter than that of groups B and C (p<0.05-0.01). The mVSS-TBSA of patients in group A was significantly improved in comparison with groups B and C at 3 and 12 months after the injury. There was no significant difference in the mortality rate between the three groups (p>0.05).

CONCLUSION

Early dermabrasion combined with porcine ADM coverage facilitates wound healing, reduces the length of hospital stay, and improves esthetic and functional results in extensive deep dermal burns with burn size over 50% TBSA.

Clinical application of cultured epithelial autografts on acellular dermal matrices in the treatment of extended burn injuries

Achieving permanent replacement of skin in extensive full-thickness and deep partial-thickness burn injuries and chronic wounds remains one of the fundamental surgical problems. Presently, split-thickness skin grafts are still considered the best material for surgical repair of an excised burn wound. However, in burns that affect greater than 50% of total body surface area, the patient has insufficient areas of unaffected skin from which split-thickness skin grafts can be harvested. The use of cultured epithelial (or epidermal) autografts (CEAs) has achieved satisfactory results. But the take rate of CEAs is poor in full-thickness bed or in chronically infected area. Providing temporary cover with allograft skin, or a more permanent allodermis, may increase clinical take. This review aims to (1) describe the use of CEAs in the regeneration of the epidermis, (2) introduce the application of the acellular dermal matrices (ADMs) in the clinics, and (3) enhance understanding of the CEAs applied with ADM as an appropriate strategy to treat the extended burn injuries. The current evidence regarding the cultured epithelial cell or keratinocyte autograft and dermal grafts applied in the treatment of burn injuries was investigated with an extensive electronic and manual search (MEDLINE and EMBASE). The included literature (N=136 publications) was critically evaluated focusing on the efficacy and safety of this technique in improving the healing of the deep dermal and full-thickness burn injuries. This review concluded that the use of ADM with CEAs is becoming increasingly routine, particularly as a life-saving tool after acute thermal trauma.

Comparative study of the effectiveness and safety of porcine and bovine atelocollagen in Asian nasolabial fold correction

Bovine-derived collagen has been used for soft-tissue augmentation since 1977. However, there are issues regarding the possibility of bovine spongiform encephalopathy (BSE). Researchers discovered that the histologic structure of porcine-derived collagen is similar to that of human dermal collagen and that it is free from the risk of BSE. This study was conducted to establish the effectiveness and safety of porcine-derived collagen compared to bovine-derived collagen. The 73 patients included in this study were healthy volunteers who responded to an advertisement approved by the Institutional Review Board (IRB). They had visited the authors' hospital complaining of wrinkles on their nasolabial fold. Either porcine (TheraFill®) or bovine atelocollagen was randomly injected into each side of their nasolabial folds, and the five-grade Wrinkle Severity Rating Scale (WSRS) was used to evaluate the wrinkles before and after the injection. The average age of the 73 study patients was 46.18 years. The WSRS scores of the porcine and bovine atelocollagen-injected patients were 2.90 ± 0.71 and 2.85 ± 0.72 at the baseline and 2.15 ± 0.70 and 2.21 ± 0.67 after 6 months. There were no statistically significant differences between the two groups. Adverse effects of the porcine atelocollagen injection were seen in 12 patients, with the most common symptom being redness. This study showed that porcine atelocollagen can be used easily and without the need for the skin testing which is necessary before bovine atelocollagen injection. The efficacy of porcine atelocollagen is also similar to that of bovine atelocollagen.

Xenogenic (porcine) acellular dermal matrix is useful for the wound healing of severely damaged extremities

This study was conducted to investigate the possibility of improving the success rate of patient treatment and promoting wound healing by utilizing xenogenic (porcine) acellular dermal matrix (XADM) to cover large areas of severely damaged wounds. Patients with severely damaged large-area wounds (56 cases) were enrolled in the study from May 2002 to May 2012. All patients admitted to hospital received a rapid infusion via intravenous access to maintain an effective circulating blood volume and to correct disorders of water and electrolytes. The wounds were exposed and covered with XADM during the initial surgery. All patients subsequently received secondary stage surgery. Of the patients, 47 cases received an autologous skin graft for wound closure, six cases underwent wound repair with a local flap and three cases underwent wound repair with an axial flap. There were two cases of amputation and three cases of mortality. The cases of two of the patients are described in detail. XADM was demonstrated to reduce the risk of emergency during surgery and improve the success rate of wound healing and patient treatment.

Porcine xenografts vs. (cryopreserved) allografts in the management of partial thickness burns: is there a clinical difference?

Porcine xenografts and cryopreserved allografts are used for the management of partial thickness burns and both biological materials have strong advocates with regard to clinical performance, the possibility of disease transfer from donor to recipient and other clinical aspects. A literature analysis was performed in an attempt to investigate whether true (statistically significant) differences exist on clinical performance and on other determinants for use. Comparing the results of this study with a similar, previously published study performed on possible differences amongst different types of allograft in the management of partial thickness burns, both allografts and porcine xenograft seem to perform equally well clinically with regard to healing related outcomes. In addition, the risk of disease transfer, in real life, was shown to be minimal. Consequently, clinical aspects being equal, other aspects such as price and availability should be used to decide which material to use for the management of partial thickness burns.

Human keratinocyte growth and differentiation on acellular porcine dermal matrix in relation to wound healing potential

A number of implantable biomaterials derived from animal tissues are now used in modern surgery. Xe-Derma is a dry, sterile, acellular porcine dermis. It has a remarkable healing effect on burns and other wounds. Our hypothesis was that the natural biological structure of Xe-Derma plays an important role in keratinocyte proliferation and formation of epidermal architecture in vitro as well as in vivo. The bioactivity of Xe-Derma was studied by a cell culture assay. We analyzed growth and differentiation of human keratinocytes cultured in vitro on Xe-Derma, and we compared the results with formation of neoepidermis in the deep dermal wounds treated with Xe-Derma. Keratinocytes cultured on Xe-Derma submerged in the culture medium achieved confluence in 7-10 days. After lifting the cultures to the air-liquid interface, the keratinocytes were stratified and differentiated within one week, forming an epidermis with basal, spinous, granular, and stratum corneum layers. Immunohistochemical detection of high-molecular weight cytokeratins (HMW CKs), CD29, p63, and involucrin confirmed the similarity of organization and differentiation of the cultured epidermal cells to the normal epidermis. The results suggest that the firm natural structure of Xe-Derma stimulates proliferation and differentiation of human primary keratinocytes and by this way improves wound healing.

Acellular dermal matrix in the management of the burn patient

Although the principles of burn management are still primarily focused on survival, as advances are realized in resuscitation, nutrition, and wound management, the functional and aesthetic outcomes following burn injury have become increasingly important. Acellular dermal matrix materials, which allow surgeons to minimize skin graft donor site morbidity in the process of repairing injured areas, play a role in addressing these important issues. Many favorable reports have been published, but they are generally characterized by small sample sizes, limited objective testing, and retrospective analysis. There does appear to be some evidence for ADM application in patient populations in whom donor site availability (those with massive burns) or morbidity (children, the elderly) is a concern, but more studies are needed. In this article, the authors discuss the current applications for ADM in burn management, review the existing literature, and present opportunities for future research.

Development and characterization of a full-thickness acellular porcine cornea matrix for tissue engineering

Our aim was to produce a natural, acellular matrix from porcine cornea for use as a scaffold in developing a tissue-engineered cornea replacement. Full-thickness, intact porcine corneas were decellularized by immersion in 0.5% (wt/vol) sodium dodecyl sulfate. The resulting acellular matrices were then characterized and examined specifically for completeness of the decellularization process. Histological analyses of decellularized corneal stromas showed that complete cell and α-Gal removal was achieved, while the major structural proteins including collagen type I and IV, laminin, and fibronectin were retained. DAPI staining did not detect any residual DNA within the matrix, and the DNA contents, which reflect the presence of cellular materials, were significantly diminished in the decellularized cornea. The collagen content of the decellularized cornea was well maintained compared with native tissues. Uniaxial tensile testing indicated that decellularization did not significantly compromise the ultimate tensile strength of the tissue (P > 0.05). In vitro cytotoxicity assays using rabbit corneal fibroblast cultures excluded the presence of soluble toxins in the biomaterial. In vivo implantation to rabbit interlamellar stromal pockets showed good biocompability. In summary, a full-thickness natural acellular matrix retaining the major structural components and strength of the cornea has been successfully developed. The matrix is biocompatible with cornea-derived cells and has potential for use in corneal transplantation and tissue-engineering applications.

Functional neovascularization in tissue engineering with porcine acellular dermal matrix and human umbilical vein endothelial cells

Endothelial cells-matrix interactions play an important role in promoting and controlling network formation. In this study, porcine acellular dermal matrix (PADM) was used to guide human umbilical vein endothelial cells (HUVECs) adhesion and proliferation as a potential system for vascularization of engineered tissues. We fabricated PADM using a modified protocol and assessed their composition and ultrastructures. Subsequently, the viability of HUVECs and the formation of capillary-like networks were evaluated by seeding cells directly on PADM scaffolds or PADM digests in vitro. We further investigated the function of the HUVECs seeded on the PADM scaffolds after subcutaneous transplantation in athymic mice. Moreover, the function of the neovessels formed in the PADM scaffolds was assessed by implantation into cutaneous wounds on the backs of mice. The results showed that PADM scaffolds significantly increased proliferation of HUVECs, and the PADM digest induced HUVECs formed many tube-like structures. Moreover, HUVECs seeded on the PADM scaffolds formed numerous capillary-like networks and some perfused vascular structures after implantation into mice. PADM seeded with HUVECs and fibroblasts were also able to form many capillary-like networks in vitro. Further, these neovessels could inosculate with the murine vasculature after implantation into cutaneous wounds in mice. The advantage of this method is that the decellularized matrix not only provides signals to maintain the viability of endothelial cells but also serves as the template structure for regenerated tissue. These findings indicate that PADM seeded with HUVECs may be a potential system for successful engineering of large, thick, and complex tissues.

Evaluation of the burn healing properties of oil extraction from housefly larva in mice

AIM OF THE STUDY

To evaluate the burn wound-healing properties of oil extraction from housefly larva by employing a deep second-degree model in mice.

MATERIALS AND METHODS

The burn wound-healing properties were evaluated by employing a deep second-degree model of burn wound assay. The anti-inflammatory activity and antibacterial activity were examined by employing the xylene-induced ear swelling model in mice and a disc-diffusion assay, respectively.

RESULTS

The best wound-healing activity was observed with the oil extract of housefly larva, followed by Ching Wan Hung and the least active was that of saline solution. The oil extraction from housefly larva suppressed xylene-induced ear swelling in mice with 35.3% of the inhibition rate at the dose of 0.1 ml/30 g. The disc-diffusion assay of housefly larva oil showed positive effect to Pseudomonas aeruginosa and Staphylococcus aureus, exhibiting no antibacterial activity to Escherichia coli.

CONCLUSION

The study provides useful information that the housefly larva oil could be used as a natural ointment to heal the burn wound.

The effect of perfluorocarbon-based artificial oxygen carriers on tissue-engineered trachea

The biological effect of the perfluorocarbon-based artificial oxygen carrier (Oxygent) was investigated in tissue-engineered trachea (TET) construction. Media supplemented with and without 10% Oxygent were compared in all assessments. Partial tissue oxygen tension (PtO(2)) was measured with polarographic microprobes; epithelial metabolism was monitored by microdialysis inside the TET epithelium perfused with the medium underneath. Chondrocyte-DegraPol constructs were cultured for 1 month with the medium before glycosaminoglycan assessment and histology. Tissue reaction of TET epithelial scaffolds immersed with the medium was evaluated on the chick embryo chorioallantoic membrane. Oxygent perfusion medium increased the TET epithelial PtO(2) (51.2 +/- 0.3 mm Hg vs. 33.4 +/- 0.3 mm Hg at 200 microm thickness; 12.5 +/- 0.1 mm Hg vs. 3.1 +/- 0.1 mm Hg at 400 microm thickness, p < 0.01) and decreased the lactate concentration (0.63 +/- 0.08 vs. 0.80 +/- 0.06 mmol/L, p < 0.05), lactate/pyruvate (1.87 +/- 0.26 vs. 3.36 +/- 10.13, p < 0.05), and lactate/glucose ratios (0.10 +/- 0.00 vs. 0.29 +/- 0.14, p < 0.05). Chondrocyte-DegraPol in Oxygent group presented lower glycosaminoglycan value (0.03 +/- 0.00 vs. 0.13 +/- 0.00, p < 0.05); histology slides showed poor acid mucopolysaccharides formation. Orthogonal polarization spectral imaging showed no difference in functional capillary density between the scaffolds cultured on chorioallantoic membranes. The foreign body reaction was similar in both groups. We conclude that Oxygent increases TET epithelial PtO(2), improves epithelial metabolism, does not impair angiogenesis, and tends to slow cartilage tissue formation.

Current scales for assessing human scarring: a review

Patients can have wide-ranging problems related to scars, in terms of cosmesis, function, symptoms, psychological problems and overall quality of life issues. A range of treatments have been recommended for problematic scarring, however it has been acknowledged that the evidence base for most of the recommendations for scar therapy is limited, with few studies using validated measures of scar assessment in generating data. This review critically evaluates the subjective scar assessment scales developed to date and provides an insight into developments required in this area for the future. The principles of psychometric theory are discussed as a means of developing reliable and valid outcome measures and these are also applicable for measuring outcomes in other fields of plastic surgery research.

Cell colonization in degradable 3D porous matrices

Cell colonization is an important in a wide variety of biological processes and applications including vascularization, wound healing, tissue engineering, stem cell differentiation and biosensors. During colonization porous 3D structures are used to support and guide the ingrowth of cells into the matrix. In this review, we summarize our understanding of various factors affecting cell colonization in three-dimensional environment. The structural, biological and degradation properties of the matrix all play key roles during colonization. Further, specific scaffold properties such as porosity, pore size, fiber thickness, topography and scaffold stiffness as well as important cell material interactions such as cell adhesion and mechanotransduction also influence colonization.

Nonsurgical management of hypertrophic scars: evidence-based therapies, standard practices, and emerging methods

Hypertrophic scars, resulting from alterations in the normal processes of cutaneous wound healing, are characterized by proliferation of dermal tissue with excessive deposition of fibroblast-derived extracellular matrix proteins, especially collagen, over long periods, and by persistent inflammation and fibrosis. Hypertrophic scars are among the most common and frustrating problems after injury. As current aesthetic surgical techniques become more standardized and results more predictable, a fine scar may be the demarcating line between acceptable and unacceptable aesthetic results. However, hypertrophic scars remain notoriously difficult to eradicate because of the high recurrence rates and the incidence of side effects associated with available treatment methods. This review explores the various treatment methods for hypertrophic scarring described in the literature including evidence-based therapies, standard practices, and emerging methods, attempting to distinguish those with clearly proven efficiency from anecdotal reports about therapies of doubtful benefits while trying to differentiate between prophylactic measures and actual treatment methods. Unfortunately, the distinction between hypertrophic scar treatments and keloid treatments is not obvious in most reports, making it difficult to assess the efficacy of hypertrophic scar treatment.

The study of inhibiting systematic inflammatory response syndrome by applying xenogenic (porcine) acellular dermal matrix on second-degree burns

OBJECTIVE

To investigate the influence of xenogenic (porcine) acellular dermal matrix on the systematic inflammatory reaction syndrome (SIRS), and the reaction of burn patients to tissue damage upon application to second-degree burn wounds.

METHOD

Seventy-two cases of patients with acute second-degree burns were enrolled in the study. According to the total burn surface area (TBSA) and the treatment methods, we randomly divided the patients into four groups. Group A (treatment group): patients with less than 30% TBSA covered with xenogenic acellular dermal matrix. Group B (control group): patients with less than 30% TBSA covered with betadine ointment gauzes. Group C (treatment group): patients with more than 30% TBSA covered with porcine acellular dermal matrix. Group D (control group): patients with more than 30% TBSA covered with betadine ointment gauzes. Serum level of C-reactive protein (CRP) was measured by single radial immunodiffusion method on 1, 4, 7 and 14 days postburn.

RESULTS

The serum level of CRP in group A was significantly less than that of in group B (P<0.05) on days 4, 7 and 14. The serum level of CRP in group C increased slowly, descended quickly and was significantly less than that of in group D on days 4, 7 and 14.

CONCLUSION

The application of xenogenic (porcine) acellular dermal matrix on second-degree burn wound can decrease serum level of CRP of the patients, which may play an important role in reducing SIRS and sepsis incidence.