Promotion of dermal regeneration using pullulan/gelatin porous skin substitute

Tissue‐engineered dermal substitutes represent a promising approach to improve wound healing and provide more sufficient regeneration, compared with current clinical standards on care of large wounds, early excision, and grafting of autografts. However, inadequate regenerative capacity, impaired regeneration/degradation profile, and high cost of current commercial tissue‐engineered dermal regeneration templates hinder their utilization, and the development of an efficient and cost‐effective tissue‐engineered dermal substitute remains a challenge. Inspired from our previously reported data on a pullulan/gelatin scaffold, here we present a new generation of a porous pullulan/gelatin scaffold (PG2) served as a dermal substitute with enhanced chemical and structural characteristics. PG2 shows excellent biocompatibility (viability, migration, and proliferation), assessed by in vitro incorporation of human dermal fibroblasts in comparison with the Integra® dermal regeneration template (Control). When applied on a mouse full‐thickness excisional wound, PG2 shows rapid scaffold degradation, more granulation tissue, more collagen deposition, and more cellularity in comparison with Control at 20 days post surgery. The faster degradation is likely due to the enhanced recruitment of inflammatory macrophages to the scaffold from the wound bed, and that leads to earlier maturation of granulation tissue with less myofibroblastic cells. Collectively, our data reveal PG2's characteristics as an applicable dermal substitute with excellent dermal regeneration, which may attenuate scar formation.     

Restoring full‐thickness defects with spray skin in conjunction with dermal regenerate template and split‐thickness skin grafting: a pilot study

Complex, full‐thickness soft tissue defects secondary to large burns, trauma and war‐related injuries continue to challenge reconstructive surgeons. To achieve positive surgical outcomes in these patient populations, novel approaches are needed to restore the functional, protective and aesthetic properties of skin. Herein, we provide the first report describing the staged use of a dermal regenerate template (DRT) with a spray‐on epidermal regenerative modality (spray skin) in addition to autologous split‐thickness skin grafting (STSG) in non‐burn trauma and compare these results with those of patients treated with DRT and STSG alone. A pilot study was performed to evaluate whether the use of spray skin technology (ReCell, Avita Medical) as an adjunct to DRT (Integra, Integra Lifesciences) and autologous skin grafting in the treatment of patients with large full‐thickness soft tissue losses impacts donor site burden as well as recipient and donor site re‐epithelialization. In this retrospective study, two patients who were treated with DRT and STSG alone (control group) were compared with two patients who were treated with DRT and spray skin/STSG in combination (experimental group). The mechanisms of injury, total defect and treatment sizes, time to complete re‐epithelialization, lengths of follow‐up, outcomes and complications were reviewed. Our group observed that using a DRT in conjunction with spray skin/STSG can reduce donor site burden and decrease time to complete healing. It can also permit greater or larger meshing ratios, while aiding in improved re‐pigmentation when compared with similar wounds treated with a DRT and autologous skin grafting alone. Copyright © 2017 John Wiley & Sons, Ltd.     

Generation of a bioengineered autologous bone substitute for palate repair: an in vivo study in laboratory animals

We carried out an in vivo study to evaluate the potential usefulness of a novel bioengineered bone substitute for the repair of palate defects in laboratory rabbits, using tissue‐engineering methods. Our results showed that the use of a bioengineered bone substitute was associated with more symmetrical palate growth as compared to the controls, and the length and height of the palate were very similar on both sides of the palate, with differences from negative controls 4 months after artificial bone grafting for bone length. The histological analysis revealed that the regenerated bone was well organized and expressed osteocalcin. In contrast, bone corresponding to control animals without tissue grafting was immature, with areas of osteoid tissue and remodelling, as determined by MMP‐14 expression. These results suggest that bone substitutes may be a useful strategy to induce the formation of a well‐structured palate bone, which could prevent the growth alterations found in cleft palate patients. This opens a door to a future clinical application of these bone substitutes. Copyright © 2015 John Wiley & Sons, Ltd.     

Cell viability and angiogenic potential of a bioartificial adipose substitute

An implantable scaffold pre‐seeded with cells needs to remain viable and encourage rapid angiogenesis in order to replace injured tissues, especially for tissue defect repairs. We created a bioartificial adipose graft composed of an electrospun 3D nanofibrous scaffold and fat tissue excised from New Zealand white rabbits. Cell viability and angiogenesis potential of the bioartificial substitute were examined during four weeks of culture in Dulbecco's Modified Eagle Medium by immunohistochemical staining with LIVE/DEAD® cell kit and PECAM‐1 antibody, respectively. In addition, a Matrigel® assay was performed to examine the possibility of blood vessels sprouting from the bioartificial graft. Our results showed that cells within the graft were viable and vascular tubes were present at week 4, while cells in a fat tissue block were dead in vitro. In addition, capillaries were observed sprouting from the graft into the Matrigel, demonstrating its angiogenic potential. We expect that improved cell viability and angiogenesis in the bioartificial substitute, compared to intact autologous graft, could potentially contribute to its survival following implantation. Copyright © 2012 John Wiley & Sons, Ltd.     

Dermal matrix scaffold engineered with adult mesenchymal stem cells and platelet-rich plasma as a potential tool for tissue repair and regeneration

The purpose of this study was to investigate the efficacy of Integra, an artificial dermal matrix used as a dermal template for skin regeneration, to form a multifunctional scaffold with human bone marrow-derived mesenchymal stem cells (hMSCs) and platelet-rich plasma (PRP) for tissue engineering and regenerative technology. First, we showed that PRP, used as a supplement for growth medium, represented an optimal substitute for animal serum as well as a source of multiple growth factors, was able to satisfactorily support cell viability and cell proliferation and influence stemness gene expression in hMSCs. Moreover, Integra appeared to be a suitable substrate for hMSCs colonization, as judged by two-photon microscopy combined with fluorescence lifetime imaging (FLIM) and confocal analysis. The cells were then seeded on Integra + PRP for 24 and 48 h. Notably, in these conditions, the seeded cells exhibited a greater aptitude to colonize the scaffold, showed improved cell adhesion and spreading as compared with those cultured on Integra alone, and acquired a fibroblast-like phenotype, indicating that the bioengineered scaffold provided an appropriate environment for cellular growth and differentiation. In conclusion, these results, although preliminary, provide clues for the design of new therapeutic strategies for skin regeneration, consisting in the combination of mesenchymal stem cells with engineered biomaterials.     

Electrospun poly(hydroxybutyrate) scaffolds promote engraftment of human skin equivalents via macrophage M2 polarization and angiogenesis

Human dermo‐epidermal skin equivalents (DE) comprising in vitro expanded autologous keratinocytes and fibroblasts are a good option for massive burn treatment. However, the lengthy expansion time required to obtain sufficient surface to cover an extensive burn together with the challenging surgical procedure limits their clinical use. The integration of DE and biodegradable scaffolds has been proposed in an effort to enhance their mechanical properties. Here, it is shown that poly(hydroxybutyrate) electrospun scaffolds (PHB) present good biocompatibility both in vitro and in vivo and are superior to poly‐ε‐caprolactone electrospun scaffolds as a substrate for skin reconstruction. Implantation of PHB scaffolds in healthy rats polarized macrophages to an M2‐type that promoted constructive in vivo remodelling. Moreover, implantation of DE‐PHB composites in a NOD/SCID mouse xenograft model resulted in engraftment accompanied by an increase in angiogenesis that favoured the survival of the human graft. Thus, PHB scaffolds are an attractive substrate for further exploration in skin reconstruction procedures, probably due in part to their greater angiogenic and M2 macrophage polarization properties. Copyright © 2017 John Wiley & Sons, Ltd.     

Foreskin‐isolated keratinocytes provide successful extemporaneous autologous paediatric skin grafts

Severe burns in children are conventionally treated with split‐thickness skin autografts or epidermal sheets. However, neither early complete healing nor quality of epithelialization is satisfactory. An alternative approach is to graft isolated keratinocytes. We evaluated paediatric foreskin and auricular skin as donor sources, autologous keratinocyte transplantation, and compared the graft efficiency to the in vitro capacities of isolated keratinocytes to divide and reconstitute epidermal tissue. Keratinocytes were isolated from surgical samples by enzymatic digestion. Living cell recovery, in vitro proliferation and epidermal reconstruction capacities were evaluated. Differentiation status was analysed, using qRT–PCR and immunolabelling. Eleven children were grafted with foreskin‐derived (boys) or auricular (girls) keratinocyte suspensions dripped onto deep severe burns. The aesthetic and functional quality of epithelialization was monitored in a standardized way. Foreskin keratinocyte graft in male children provides for the re‐epithelialization of partial deep severe burns and accelerates wound healing, thus allowing successful wound closure, and improves the quality of scars. In accordance, in vitro studies have revealed a high yield of living keratinocyte recovery from foreskin and their potential in terms of regeneration and differentiation. We report a successful method for grafting paediatric males presenting large severe burns through direct spreading of autologous foreskin keratinocytes. This alternative method is easy to implement, improves the quality of skin and minimizes associated donor site morbidity. In vitro studies have highlighted the potential of foreskin tissue for graft applications and could help in tissue selection with the prospect of grafting burns for girls. Copyright © 2013 John Wiley & Sons, Ltd.     

Synthesis and in vivo integration of improved concentrated collagen hydrogels

Normal collagen hydrogels, currently used as the dermal layer of skin substitute Apligraf®, are obtained by encapsulating dermal fibroblasts in a collagen hydrogel at low concentration (0.66 mg/ml). However they suffer from extensive contraction by cells and weak resistance against degradation, which limits their use as permanent graft. We have previously shown that concentrated collagen hydrogels at 3 mg/ml exhibit an improved performance in this respect but nevertheless degrade in vivo to ca. 50% of their initial area after 1 month. We have now investigated a new procedure to synthesize more concentrated collagen hydrogels at 5 mg/ml in order to improve hydrogel resistance and integration capability. The constructs were implanted in subcutaneous pockets in a rat model and analysed after 15 and 30 days. They were still visible after 1 month without any reduction of their area. Histological analysis revealed rapid colonization of the implants by host cells. Neovascularization was observed and reached the core of the implant at day 15. Moreover, cell colonization was not associated with a severe host response. The absence of apoptotic cells evidenced cell viability and the neosynthesis of collagen III a remodelling process. These novel non‐crosslinked and cost‐effective materials show superior stability and in vivo integration compared to less concentrated collagen hydrogels and appear promising for the treatment of skin lesions. Copyright © 2010 John Wiley & Sons, Ltd.     

Bioengineering and in utero transplantation of fetal skin in the sheep model: A crucial step towards clinical application in human fetal spina bifida repair

An intricate problem during open human fetal surgery for spina bifida regards back skin closure, particularly in those cases where the skin defect is much too large for primary closure. We hypothesize that tissue engineering of fetal skin might provide an adequate autologous skin substitute for in utero application in such situations. Eight sheep fetuses of four time‐mated ewes underwent fetoscopic skin biopsy at 65 days of gestation. Fibroblasts and keratinocytes isolated from the biopsy were used to create fetal dermo‐epidermal skin substitutes. These were transplanted on the fetuses by open fetal surgery at 90 days of gestation on skin defects (excisional wounds) created during the same procedure. Pregnancy was allowed to continue until euthanasia at 120 days of gestation. The graft area was analyzed macroscopically and microscopically. The transplanted fetal dermo‐epidermal skin substitutes was well discernable in situ in three of the four fetuses available for analysis. Histology confirmed healed grafts with a close to natural histological skin architecture four weeks after in utero transplantation. This experimental study generates evidence that laboratory grown autologous fetal skin analogues can successfully be transplanted in utero. These results have clinical implications as an analogous procedure might be applied in human fetuses undergoing prenatal repair to facilitate primary skin closure. Finally, this study may also fertilize the field of fetal tissue engineering in general, particularly when more interventional, minimally invasive, and open fetal surgical procedures become available.     

复合皮移植修复创面的临床观察

目的 观察移植以小肠黏膜下层（SIS）为真皮替代物体外构建的复合皮修复创面的效果。方法制取家猪空肠黏膜下层为真皮替代物,致密层表面种植自体表皮细胞,构建人工复合皮,移植复合皮修复37例皮肤肉芽组织创面;观察复合皮早期成活率,并分别于移植后第1周、第2周取复合皮标本作组织学观察。结果表皮细胞在SIS表面定位、生长,24例移植的复合皮早期成活良好,SIS内新生血管形成,炎性细胞浸润,无移植排斥反应。结论以SIS为真皮替代物构建的复合皮,有可能成为一种新型的创面修复材料。     

Comparison of two decellularized dermal equivalents

Immunologically inert allogeneic acellular dermal scaffolds provide a matrix with molecular architecture close to native tissues, which synthetic scaffolds cannot. Not all nature‐derived scaffolds possess the same biological and physical properties. The different properties of scaffolds supporting cellular growth used for manufacturing tissue engineered grafts could lead to different implantation results. The scaffold properties should be carefully considered in order to meet the expected outcomes of tissue engineered grafts. In this report, we evaluated the cellular growth on AlloDerm® and Allopatch, 2 acellular scaffolds derived from human cadaver skin, using a fabricated 3D organotypic culture with primary human oral keratinocytes to produce an ex vivo produced oral mucosa equivalent (EVPOME). A well stratified epithelium could be constructed on both scaffolds. AlloDerm® and Allopatch EVPOMEs were also implanted into severe combined immunodeficiency mice to compare the ingrowth of blood vessels into the dermal component of the two EVPOMEs. Blood vessel counts were 3.3 times higher (p = .01) within Allopatch EVPOMEs than within AlloDerm® EVPOMEs. An oral and skin keratinocyte co‐culture, separated by a physical barrier to create a cell‐free zone, was used to evaluate cell migration on AlloDerm® and Allopatch. Slower cell migration was observed on Allopatch than on AlloDerm®.     

Comparison of advanced therapy medicinal product gingiva and skin substitutes and their in vitro wound healing potentials

Skin and oral mucosa substitutes are a therapeutic option for closing hard‐to‐heal skin and oral wounds. Our aim was to develop bi‐layered skin and gingiva substitutes, from 3 mm diameter biopsies, cultured under identical conditions, which are compliant with current European regulations for advanced therapy medicinal products. We present in vitro mode of action methods to (i) determine viability: epithelial expansion, proliferation (Ki‐67), metabolic activity (MTT assay); (ii) characterize skin and gingiva substitutes: histology and immunohistochemistry; and (iii) determine potency: soluble wound healing mediator release (enzyme‐linked immunosorbent assay). Both skin and gingiva substitutes consist of metabolically active autologous reconstructed differentiated epithelium expanding from the original biopsy sheet on a fibroblast populated connective tissue matrix (donor dermis). Gingival epithelium expanded 1.7‐fold more than skin epithelium during the 3 week culture period. The percentage of proliferating Ki‐67‐positive cells located in the basal layer of the gingiva substitute was >1.5‐fold higher than in the skin substitute. Keratins 16 and 17, which are upregulated during normal wound healing, were expressed in both the skin and gingiva substitutes. Notably, the gingiva substitute secreted higher amounts of key cytokines involved in mitogenesis, motogenesis and chemotaxis (interleukin‐6 > 23‐fold, CXCL8 > 2.5‐fold) as well as higher amounts of the anti‐fibrotic growth factor, hepatocyte growth factor (>7‐fold), compared with the skin substitute. In conclusion, while addressing the viability, characterization and potency of the tissue substitutes, important intrinsic differences between skin and gingiva were discovered that may explain in part the superior quality of wound healing observed in the oral mucosa compared with skin.     

Rapid treatment of full‐thickness skin loss using ovine tendon collagen type I scaffold with skin cells

The full‐thickness skin wound is a common skin complication affecting millions of people worldwide. Delayed treatment of this condition causes the loss of skin function and integrity that could lead to the development of chronic wounds or even death. This study was aimed to develop a rapid wound treatment modality using ovine tendon collagen type I (OTC‐I) bio‐scaffold with or without noncultured skin cells. Genipin (GNP) and carbodiimide (EDC) were used to cross‐link OTC‐I scaffold to improve the mechanical strength of the bio‐scaffold. The physicochemical, biomechanical, biodegradation, biocompatibility, and immunogenicity properties of OTC‐I scaffolds were investigated. The efficacy of this treatment approach was evaluated in an in vivo skin wound model. The results demonstrated that GNP cross‐linked OTC‐I scaffold (OTC‐I_GNP) had better physicochemical and mechanical properties compared with EDC cross‐linked OTC‐I scaffold (OTC‐I_EDC) and noncross‐link OTC‐I scaffold (OTC‐I_NC). OTC‐I_GNP and OTC‐I_NC demonstrated no toxic effect on cells as it promoted higher cell attachment and proliferation of both primary human epidermal keratinocytes and human dermal fibroblasts compared with OTC‐I_EDC. Both OTC‐I_GNP and OTC‐I_NC exhibited spontaneous formation of bilayer structure in vitro. Immunogenic evaluation of OTC‐I scaffolds, in vitro and in vivo, revealed no sign of immune response. Finally, implantation of OTC‐I_NC and OTC‐I_GNP scaffolds with noncultured skin cells demonstrated enhanced healing with superior skin maturity and microstructure features, resembling native skin in contrast to other treatment (without noncultured skin cells) and control group. The findings of this study, therefore, suggested that both OTC‐I scaffolds with noncultured skin cells could be promising for the rapid treatment of full‐thickness skin wound.     

Skin epithelial cells as possible substitutes for ameloblasts during tooth regeneration

The disappearance of ameloblasts in erupted teeth hampers the implementation of tissue engineering‐based tooth regeneration. We aimed at utilizing skin epithelial cells as the appropriate substitute for ameloblasts. The conversion potential of 1 day postnatal rat skin epithelial cells to ameloblasts was investigated under the induction of dental papillae mesenchymal cells (DPMCs). Induction strategies had been designed both in vitro and in vivo. Markers for ameloblasts had been detected in skin epithelial cells, which showed a columnar appearance with the nuclei located at one side, under indirect co‐culture with DPMCs in vitro. An enamel–dentine‐like and tooth germ‐like structure was formed by recombining skin epithelial pieces or cells with DPMCs after 14 days of implantation in rat renal capsule. Immunohistochemistry and cell labelling analysis further demonstrated that the enamel‐forming cells were skin epithelium‐derived. These results indicated that the skin epithelium‐derived cells from postnatal rats have the potential to convert to functional ameloblasts under effective induction. Copyright © 2012 John Wiley & Sons, Ltd.     

离体皮肤氧耗量测定与微机数据分析系统

目的比较长短氧传感器常规手工计算法和微机数据分析法测定皮片氧耗活力的效果。方法将Wistar鼠薄皮片分别切成直径为15mm和6mm的小皮片,一部分皮片立即测定氧耗量和另一部分皮片液氮冻存。两种氧传感器对每块皮片各测定两次,然后按常规法和微机法计算测定皮片1min的氧耗量。结果两种氧传感器常规法和微机法测定新鲜皮片的氧耗量各组内均无显著性差异(P>0.05);但长氧传感器测定的氧耗量比短氧传感器测得的氧耗量显著高(P<0.05)。两种氧传感器微机法测定皮片的氧耗量比常规法测定皮片的氧耗量显著高(P<0.05)。长氧传感器和微机法测定冻存皮片的氧耗量比新鲜皮片氧耗量显著低(P<0.01)。结论结果提示长氧传感器比短氧传感器测定皮片氧耗量更高、用皮量更少,而微机法比常规法更加简便可靠。     

Development of a mechanically stable support for the osteoinductive biomaterial COLLOSS® E

The application of bone graft substitutes with osteoinductive properties is of high importance for the repair of large bone defects. COLLOSS^® E, a protein lyophilizate extracted from equine long bones, exhibits an osteoinductive potential which has been proven in several studies. In this work, a mechanically stable, but biodegradable support for COLLOSS^® E has been developed aiming at a bone graft substitute that retains shape and size when coming in contact with body fluids. Mineralization of collagen type I, isolated from horse tendon, resulted in a stable collagen hydroxyapatite nanocomposite. By means of freeze drying, this composite was used to prepare 3D scaffolds which can be filled with the cotton‐wool like COLLOSS^® E material. These scaffolds exhibit a porous microstructure and a good mechanical stability in dry and wet state. Cell culture experiments with human bone marrow stromal cells (hBMSC) revealed the cytocompatibility of the newly developed composite material. Cells were able to adhere, proliferate and differentiate into the osteoblastic lineage. The osteoinductive nature of COLLOSS^® E has been demonstrated by a significant higher activity of the osteogenic marker alkaline phosphatase (ALP) on combined scaffolds (mineralized collagen scaffolds filled with COLLOSS^® E) compared to pure scaffolds. The combination of COLLOSS^® E with scaffolds made of a collagen hydroxyapatite composite results in a synthetic bone graft substitute which can be completely remodelled into vital bone tissue opening an interesting new possibility for the therapy of bone defects. Copyright © 2008 John Wiley & Sons, Ltd.     

Effects of local forearm skin heating on skin properties

This study investigated impacts of local skin heating on skin properties and tested whether skin changes depended on heat‐induced hyperaemia. It was reasoned that heat‐induced vasodilation impacts accompanying interstitial fluid changes. Forearm skin was locally heated from a baseline of 35°C to 40–42°C in 30 young adults (15 females, 15 males, 24.9 ± 2.1 years) and non‐heated in 10 others (5 females, 5 males, 25.2 ± 1.3 years. Skin blood flow (SBF) was continuously measured using a laser Doppler method and skin tissue dielectric constant (TDC), stratum corneum capacitance (SCC) and transepidermal water loss (TEWL) were measured before and after maintained heat for 12 min. TDC values were determined to effective measurement depths of 1.5 mm (TDC15) and 2.5 mm (TDC25). Results showed a large heat‐induced hyperaemia, with SBF increasing on average 8.8‐fold from its baseline of 35°C. Heating also caused significant increases in TDC, SCC and TEWL that, compared to preheating, increased approximately 1.1‐fold, 3.1‐fold and 4.5‐fold. None of these skin changes correlated with the magnitude of the SBF hyperaemic response. Absence of this correlation may indicate that in young healthy adults, increased capillary filtration due to heat‐induced arteriolar vasodilation is rapidly accommodated by postcapillary reabsorption, enhanced lymphatic activity and TEWL processes. An alternate explanation is that heating caused increased red cell oscillations that were detected as part of the laser Doppler increase without representing increased capillary flux. The major determinant of the Increases in TDC, SCC and TEWL is likely a consequence of heat‐induced eccrine gland activation. Studies of older persons or those with depressed function are warranted.     

The 1999 clinical research award. Cultured skin substitutes combined with Integra Artificial Skin to replace native skin autograft and allograft for the closure of excised full-thickness burns

Prompt and permanent closure of excised full-thickness burns remains a critical factor in a patient's recovery from massive burn injuries. Hypothetically, Integra Artificial Skin (Integra) may replace the need for allografts for immediate wound coverage, and cultured skin substitutes (CSS) that contain stratified epithelium may replace the need for autografts for definitive wound closure. To test this hypothesis, 3 patients with full-thickness burns of greater than 60% of their total body surface areas had their eschar excised within 14 days of admission. Integra was applied, and a skin biopsy was collected from each patient for the preparation of CSS. At 3 weeks or more after the application of the Integra and the collection of skin biopsies, the outer silastic cover of the Integra was removed and CSS were grafted. The CSS were irrigated with nutrients and antimicrobials for 6 days and then dressed with antimicrobial ointment and cotton gauze. Treated wounds were traced on days 14 and 28 after the grafting of CSS for determination of engraftment and wound closure, respectively. Cost analysis was not performed. Engraftment on postoperative day (POD) 14 was 98%+/-1% (mean +/- standard error of the mean), the ratio of closed:donor areas on POD 28 was 52.3+/-5.2, and no treated sites required regrafting. The histology of the closed wounds showed stable epithelium that covered a layer of newly formed fibrovascular tissue above the reticulated structure of the degrading Integra. The clinical outcomes of the closed wounds after POD 28 demonstrated smooth, pliable, and hypopigmented skin. Two patients who had received CSS grafts over Integra on their backs were positioned supine on air beds from POD 8 or POD 9 with minimal graft loss because of mechanical loading. One patient with a full-thickness burn of 88% of the total body surface area was covered definitively at 55 days postburn. These results demonstrate that the combination of CSS and Integra can accomplish functionally stable and cosmetically acceptable wound closure in patients with extensive full-thickness burns. This combination of alternatives to the conventional grafting of split-thickness skin permits the substitution of cadaveric allograft with Integra and the substitution of donor autograft with CSS. This approach to the closure of excised full-thickness burns is expected to reduce greatly the time to definitive closure of burn wounds and to reduce the morbidity associated with the harvesting of donor sites for split-thickness skin autografts.     

Evaluation of DPC immulite 2000® Toxoplasma quantitative IgG/IgM kits for automated toxoplasmosis serology with immulite 2000®

In this study, we evaluated a new immunoassay for the automated detection of anti‐toxoplasma IgG and IgM with Immulite 2000^® (DPC‐Siemens, La Garenne‐Colombes, France). We tested 280 sera from 112 patients with past infection (PI), 40 PI with residual IgM, 75 seronegatives, 16 infants (31 sera) monitored for neonatal screening of congenital toxoplasmosis, and 13 patients with recent seroconversion (SC) (22 sequential sera). Detection sensitivity and specificity for IgG were 99 and 100%, respectively. IgG titers obtained with Immulite 2000^® were higher than with Vidas^® (BioMérieux, Marcy I'Etoile, France) and Access^® (Beckman‐Coulter, Villepinte, France) (paired Wilcoxon test z=4.44 and z=3.67, respectively, P<0.001). IgM specificity was 100%. Detection sensitivity for IgM was 100% in the SC group, 86% in congenitally infected infants, and 75% in PI with persistent IgM. IgM detection seemed less prolonged in time than with the IgM Access^® and ISAGA^® IgM techniques. J. Clin. Lab. Anal. 23:336–340, 2009. © 2009 Wiley‐Liss, Inc.     

Collagen hydrogels strengthened by biodegradable meshes are a basis for dermo‐epidermal skin grafts intended to reconstitute human skin in a one‐step surgical intervention

Extensive full‐thickness skin loss, associated with deep burns or other traumata, represents a major clinical problem that is far from being solved. A promising approach to treat large skin defects is the use of tissue‐engineered full‐thickness skin analogues with nearly normal anatomy and function. In addition to excellent biological properties, such skin substitutes should exhibit optimal structural and mechanical features. This study aimed to test novel dermo‐epidermal skin substitutes based on collagen type I hydrogels, physically strengthened by two types of polymeric net‐like meshes. One mesh has already been used in clinical trials for treating inguinal hernia; the second one is new but consists of a FDA‐approved polymer. Both meshes were integrated into collagen type I hydrogels and dermo‐epidermal skin substitutes were generated. Skin substitutes were transplanted onto immuno‐incompetent rats and analyzed after distinct time periods. The skin substitutes homogeneously developed into a well‐stratified epidermis over the entire surface of the grafts. The epidermis deposited a continuous basement membrane and dermo‐epidermal junction, displayed a well‐defined basal cell layer, about 10 suprabasal strata and a stratum corneum. Additionally, the dermal component of the grafts was well vascularized. Copyright © 2012 John Wiley & Sons, Ltd.