Cryopreserved cultured epidermal allografts achieved early closure of wounds and reduced scar formation in deep partial-thickness burn wounds (DDB) and split-thickness skin donor sites of pediatric patients

Mesenchymal stem cells in craniofacial reconstruction: a comprehensive review

Craniofacial reconstruction faces many challenges, including high complexity, strong specificity, severe injury, irregular and complex wounds, and high risk of bleeding. Traditionally, the "gold standard" for treating craniofacial bone defects has been tissue transplantation, which involves the transplantation of bone, cartilage, skin, and other tissues from other parts of the body. However, the shape of craniofacial bone and cartilage structures varies greatly and is distinctly different from ordinary long bones. Craniofacial bones originate from the neural crest, while long bones originate from the mesoderm. These factors contribute to the poor effectiveness of tissue transplantation in repairing craniofacial defects. Autologous mesenchymal stem cell transplantation exhibits excellent pluripotency, low immunogenicity, and minimally invasive properties, and is considered a potential alternative to tissue transplantation for treating craniofacial defects. Researchers have found that both craniofacial-specific mesenchymal stem cells and mesenchymal stem cells from other parts of the body have significant effects on the restoration and reconstruction of craniofacial bones, cartilage, wounds, and adipose tissue. In addition, the continuous development and application of tissue engineering technology provide new ideas for craniofacial repair. With the continuous exploration of mesenchymal stem cells by researchers and the continuous development of tissue engineering technology, the use of autologous mesenchymal stem cell transplantation for craniofacial reconstruction has gradually been accepted and promoted. This article will review the applications of various types of mesenchymal stem cells and related tissue engineering in craniofacial repair and reconstruction.

Comparing the Effects of Two Cryoprotectant Protocols, Dimethyl-Sulfoxide (DMSO) and Glycerol, on the Recovery Rate of Cultured Keratinocytes on Amniotic Membrane

Background: Off-the-shelf supply of viable engineered tissue is critical for effective and fast treatment of life-threatening injuries such as deep burns. An expanded keratinocyte sheet on the human amniotic membrane (KC sheet-HAM) is a beneficial tissue-engineering product for wound healing. To access an on-hand supply for the widespread application and overcome the time-consuming process, it is necessary to develop a cryopreservation protocol that guarantees the higher recovery of viable keratinocyte sheets after freeze-thawing. This research aimed to compare the recovery rate of KC sheet-HAM after cryopreservation by dimethyl-sulfoxide (DMSO) and glycerol. Methods: Amniotic membrane was decellularized with trypsin, and keratinocytes were cultured on it to form a multilayer, flexible, easy-to-handle KC sheet-HAM. The effects of 2 different cryoprotectants were investigated by histological analysis, live-dead staining, and proliferative capacity assessments before and after cryopreservation. Results: KCs well adhered and proliferated on the decellularized amniotic membrane and successfully represented 3 to 4 stratified layers of epithelialization after 2 to 3 weeks culture period; making it easy to cut, transfer, and cryopreserve. However, viability and proliferation assay indicated that both DMSO and glycerol cryosolutions have detrimental effects on KCs, and KCs-sheet HAM could not recover to the control level after 8 days of culture post-cryo. The KC sheet lost its stratified multilayer nature on AM, and sheet layers were reduced in both cryo-groups compared to the control. Conclusion: Expanding keratinocytes on the decellularized amniotic membrane as a multilayer sheet made a viable easy-to-handle sheet, nonetheless cryopreservation reduced viability and affected histological structure after thawing. Although some viable cells were detectable, our research highlighted the need for a better cryoprotectant protocol other than DMSO and glycerol, specific for the successful banking of viable tissue constructs.

Convergence of Biofabrication Technologies and Cell Therapies for Wound Healing

BACKGROUND

Cell therapy holds great promise for cutaneous wound treatment but presents practical and clinical challenges, mainly related to the lack of a supportive and inductive microenvironment for cells after transplantation. Main: This review delineates the challenges and opportunities in cell therapies for acute and chronic wounds and highlights the contribution of biofabricated matrices to skin reconstruction. The complexity of the wound healing process necessitates the development of matrices with properties comparable to the extracellular matrix in the skin for their structure and composition. Over recent years, emerging biofabrication technologies have shown a capacity for creating complex matrices. In cell therapy, multifunctional material-based matrices have benefits in enhancing cell retention and survival, reducing healing time, and preventing infection and cell transplant rejection. Additionally, they can improve the efficacy of cell therapy, owing to their potential to modulate cell behaviors and regulate spatiotemporal patterns of wound healing.

CONCLUSION

The ongoing development of biofabrication technologies promises to deliver material-based matrices that are rich in supportive, phenotype patterning cell niches and are robust enough to provide physical protection for the cells during implantation.

Adipose stromal vascular fraction: a promising treatment for severe burn injury

Thermal skin burn injury affects both adults and children globally. Severe burn injury affects a patient's life psychologically, cosmetically, and socially. The pathophysiology of burn injury is well known. Due to the complexity of burn pathophysiology, the development of specific treatment aiding in tissue regeneration is required. Treatment of burn injury depends on burn severity, size of the burn and availability of donor site. Burn healing requires biochemical and cellular events to ensure better cell response to biochemical signals of the healing process. This led to the consideration of using cell therapy for severe burn injury. Adult mesenchymal stem cells have become a therapeutic option because of their ability for self-renewal and differentiation. Adipose stromal vascular fraction (SVF), isolated from adipose tissues, is a heterogeneous cell population that contains adipose-derived stromal/stem cells (ADSC), stromal, endothelial, hematopoietic and pericytic lineages. SVF isolation has advantages over other types of cells; such as heterogeneity of cells, lower invasive extraction procedure, high yield of cells, and fast and easy isolation. Therefore, SVF has many characteristics that enable them to be a therapeutic option for burn treatment. Studies have been conducted mostly in animal models to investigate their therapeutic potential for burn injury. They can be used alone or in combination with other treatment options. Treatment with both ADSCs and/or SVF enhances burn healing through increasing re-epithelization, angiogenesis and decreasing inflammation and scar formation. Research needs to be conducted for a better understanding of the SVF mechanism in burn healing and to optimize current techniques for enhanced treatment outcomes.

An Anhydrous Sodium Chloride Skin Preservation Model for Studies on Keratinocytes Grafting into the Wounds

Background. Human skin is needed for covering large body areas lost by trauma. The shortcomings of contemporary methods of skin storage are limited preservation time and high immunogenicity if allogeneic. Methods. We investigated whether long-lasting skin preservation in anhydrous sodium chloride (NaCl) may be the source of keratinocytes (KCs) for transplantation. Dehydrated skin fragments were preserved for a time frame from 1 week to 12 months. Then, skin fragments were rehydrated, and KCs were isolated. The viability of KCs was assessed in viability/cytotoxicity test. NaCl-preserved KCs were cultured for 7 days and transplanted to the dorsum of SCID mice. Results. The morphology of NaCl-preserved KCs was unaltered. KCs from all epidermal layers could be identified. All grafts were accepted by the recipients. Transplanted KCs: synthesized keratins 10 and 16 expressed antigens specific for stem cells and transient-amplifying cells, and remained HLA-I-positive. Moreover, they expressed the proliferative marker PCNA. Cells isolated from transplants remained viable and produced enzymes. Conclusions. Transplantation of KCs obtained from human skin and stored in anhydrous NaCl may be considered for the closure of extensive skin wounds. The originality of this method consists of an effective storage procedure and easy preparation of keratinocytes for transplantation.

Efficacy of Cultured Allogenic Keratinocytes in Treatment of Deep Second-Degree Burn

Cultured allogenic keratinocytes, produced as Kaloderm® (Tego Science, Seoul, Korea), are an effective dressing material for burn wounds. Generally, deep second-degree contact, steam, and flame burns tend to progress to third-degree burns. This study reviews the efficacy of cultured allogenic keratinocytes in deep second-degree burn patients. This is a retrospective study of 64 patients treated between November 2013 and April 2019. A half of deep second-degree contact, steam, and flame burn patients were treated with cultured allogenic keratinocytes. The other half were treated with chlorhexidine gauze and antibiotic ointment. The primary outcome was time to wound closure. A secondary outcome was the number of Kaloderm sheets used. Groups were compared based on the type of burn and treatment. In the experimental group, the median times to reepithelization were 10.0 days for the contact burn group, 13.5 days for the flame burn group, and 11.0 days for the steam burn group. Progression to a third-degree burn occurred in only one patient in the experimental group and four patients in the control group. Patients treated with cultured allogenic keratinocytes required a mean time of 11.7 ± 2.4 days for complete closure, whereas the mean time to complete closure in the control group was 16.4 ± 5.3 days. Patients with deep second-degree burns from flame, steam, and contact treated with cultured allogenic keratinocytes reepithelialized faster than those treated with chlorhexidine dressings.

Local Treatment of Burns with Cell-Based Therapies Tested in Clinical Studies

Effective wound management is an important determinant of the survival and prognosis of patients with severe burns. Thus, novel techniques for timely and full closure of full-thickness burn wounds are urgently needed. The purpose of this review is to present the current state of knowledge on the local treatment of burn wounds (distinguishing radiation injury from other types of burns) with the application of cellular therapies conducted in clinical studies. PubMed search engine and ClinicalTrials.gov were used to analyze the available data. The analysis covered 49 articles, assessing the use of keratinocytes (30), keratinocytes and fibroblasts (6), fibroblasts (2), bone marrow-derived cells (8), and adipose tissue cells (3). Studies on the cell-based products that are commercially available (Epicel^®, Keraheal™, ReCell^®, JACE, Biobrane^®) were also included, with the majority of reports found on autologous and allogeneic keratinocytes. Promising data demonstrate the effectiveness of various cell-based therapies; however, there are still scientific and technical issues that need to be solved before cell therapies become standard of care. Further evidence is required to demonstrate the clinical efficacy and safety of cell-based therapies in burns. In particular, comparative studies with long-term follow-up are critical.

Cryopreserved cultured epithelial allografts for pediatric deep partial dermal burns: Early wound closure and suppression of scarring

BACKGROUND

In deep partial thickness dermal burns (DDB) where greater than 50% of the dermis is lost, severe pain, scarring and contractures occur. Therefore, skin grafting may be required. In children, scar contracture occurs because scarred skin does not stretch with growth creating the need for additional scar-releasing or skin-grafting surgeries. In order to resolve this problem, we used cryopreserved cultured epithelial allograft (cryopreserved allo-CEG), which can be grafted shortly after sustaining a wound. We reevaluated the promotion of early wound closure of burns and suppression of scarring by this treatment.

METHODS

Cryopreserved allo-CEGs were used to treat 50 cases of pediatric DDB from 1992 to 2000. These cases were reviewed with regard to the time until epithelialization, take percentage, and pain level. Also, in order to examine why cryopreserved allo-CEG promotes healing of burns and suppresses scarring, growth factors and cytokines in the cryopreserved allo-CEG were measured. Cryopreserved allo-CEG sheets were solubilized and concentrations of TGF-α, TGF-β1, IL-1α, IL-1β, PDGF-AA, VEGF, KGF, IL-6, b-FGF, as well as metalloprotease-1 (MMP-1) and HGF, which are noted to have scarring suppression effects, were measured before grafting.

RESULTS

Grafting of cryopreserved allo-CEGs in 50 cases of childhood DDB resulted in early epithelialization (9.32 ± 3.63 days on the average) and an almost 100% take rate. Also, pain relief (pain reduction or elimination, reduced need for anesthetics) was seen in all cases. Although 15-23 years have now elapsed, adverse events have not been observed. Cryopreserved allo-CEG contains IL-1α, IL-1β, PDGF-AA, TGF-α, TGF-β1, VEGF, and IL-6 have wound healing effects. The concentration of IL-1α was higher than the concentrations of other components, and this was followed by TGF-α, TGF-β1, b-FGF and VEGF. Although the concentration of MMP-1, which has a scarring suppression effect, was high, HGF was not detected.

CONCLUSION

Cryopreserved allo-CEG contains growth factors that promote wound healing and factors that suppress scarring. Three effects, namely (1) early wound closure, (2) scarring suppression, and (3) pain relief were seen with grafts of cryopreserved allo-CEG in cases of childhood DDB. These observations show that cryopreserved allo-CEG is clinically useful and effective for the treatment of childhood DDB.

Cultured autologous keratinocytes in the treatment of large and deep burns: a retrospective study over 15 years

AIM

The aim was to review the use and indications of cultured autologous epidermis (CAE) in extensive burns and to evaluate the efficiency of our strategy of burn treatment.

MATERIALS AND METHODS

This retrospective study comprised 15 years (1997-2012).

INCLUSION CRITERIA

all patients who received CAE.

EXCLUSION CRITERIA

patients who died before complete healing and patients who received exclusively cultured allogeneic keratinocytes. Evaluation criteria were clinical. Time and success of wound healing after CAE graft were evaluated.

RESULTS

A total of 63 patients were included with severity Baux score of 107 (from 70 to 140) and mean percentage of TBSA of 71% (from 40% to 97%). The CAE were used as Cuono method, in STSG donor sites and deep 2nd degree burns and in combination with large-meshed STSG (1:6-1:12) in extensively burned patients. Cuono method was used in 6 patients. The final take was 16% (0-30) because of the great fragility of the obtained epidermis. Nine patients with deep 2nd degree burns (mean TBSA 81%, from 60 to 97%) were successfully treated with only CAE without skin grafting. Combined technique (STSG meshed at 1:6-1:12 covered with CAE) was used in 27 patients (mean TBSA 69%, from 49% to 96%) with 85% success rate. Finally, donor sites treated with CAE in 49 patients could be harvested several times thanks to rapid epithelialization (time of wound healing was 7 days (from 5 to 10 days)).

CONCLUSION

The CAE allow rapid healing of STSG donor sites and deep 2nd second degree burns in extensively burned patients.

Cell therapy in dermatology

Harnessing the regenerative capacity of keratinocytes and fibroblasts from human skin has created new opportunities to develop cell-based therapies for patients. Cultured cells and bioengineered skin products are being used to treat patients with inherited and acquired skin disorders associated with defective skin, and further clinical trials of new products are in progress. The capacity of extracutaneous sources of cells such as bone marrow is also being investigated for its plasticity in regenerating skin, and new strategies, such as the derivation of inducible pluripotent stem cells, also hold great promise for future cell therapies in dermatology. This article reviews some of the preclinical and clinical studies and future directions relating to cell therapy in dermatology, particularly for inherited skin diseases associated with fragile skin and poor wound healing.

Cell therapy for wound healing

In covering wounds, efforts should include utilization of the safest and least invasive methods with goals of achieving optimal functional and cosmetic outcome. The recent development of advanced wound healing technology has triggered the use of cells to improve wound healing conditions. The purpose of this review is to provide information on clinically available cell-based treatment options for healing of acute and chronic wounds. Compared with a variety of conventional methods, such as skin grafts and local flaps, the cell therapy technique is simple, less time-consuming, and reduces the surgical burden for patients in the repair of acute wounds. Cell therapy has also been developed for chronic wound healing. By transplanting cells with an excellent wound healing capacity profile to chronic wounds, in which wound healing cannot be achieved successfully, attempts are made to convert the wound bed into the environment where maximum wound healing can be achieved. Fibroblasts, keratinocytes, adipose-derived stromal vascular fraction cells, bone marrow stem cells, and platelets have been used for wound healing in clinical practice. Some formulations are commercially available. To establish the cell therapy as a standard treatment, however, further research is needed.

Wound-healing potential of Cultured Epidermal Sheets is unaltered after lyophilization: a preclinical study in comparison to cryopreserved CES

Lyophilized Cultured Epidermal Sheets (L-CES) have been reported to be as effective as the cryopreserved CES (F-CES) in treating skin ulcers. However, unlike F-CES, no preclinical study assessing wound-healing effects has been conducted for L-CES. The present study was set out to investigate the microstructure, cytokine profile, and wound-healing effects of L-CES in comparison to those of F-CES. Keratinocytes were cultured to prepare CES, followed by cryopreservation at −70°C and lyophilization. Under microscopic observation, intact cells with apparent intracellular junctions were observed in L-CES. The L-CES, like fresh CES, consisted of three to four well-maintained epidermal layers, as shown by the expression of keratins, involucrin, and p63. There were no differences in the epidermal layer or protein expression between L-CES and F-CES, and both CES were comparable to fresh CES. TGF-α, EGF, VEGF, IL-1α, and MMPs were detected in L-CES at levels similar to those in F-CES. In a mouse study, wounds treated with L-CES or F-CES completely healed at least 4 days faster than untreated wounds. CES-treated wounds completely healed by day 10, while the untreated wounds did not heal by day 14. Masson's trichrome staining showed that collagen deposition in the CES-treated wounds was highly increased in the dermis of the wound center compared to that in the control wounds. Thus, this study demonstrates that L-CES is as clinically effective as F-CES for wound treatment.

Cultured allogenic keratinocytes for extensive burns: a retrospective study over 15 years

The aim was to review the use and indications of cultured allogenic keratinocytes (CAlloK) in extensive burns and their efficiency.

MATERIALS AND METHODS

This retrospective study comprised 15 years (1997-2012).

INCLUSION CRITERIA

all patients who received CAlloK.

EXCLUSION CRITERIA

patients who died before complete healing. Evaluation criteria were clinical. Time and success of wound healing after CAlloK use were evaluated.

RESULTS

The CAlloK were used for 2 indications - STSG donor sites and deep 2nd degree burns in extensively burned patients. A total of 70 patients were included with severity Baux score of 99.2 (from 51 to 144) and mean percentage of TBSA of 63.49% (from 21 to 96%). Fifty nine patients received CAlloK for STSG donor sites with a mean number of applications of 4 and mean surface of 3800 cm(2) per patient. Treated donor sites were re-harvested 2.5 times. The mean time of complete epithelialization was 7 days. In 11 patients, CAlloK were used for deep 2nd degree burns. The mean percentage of burned surface was 73.7%. The mean surface of CAlloK per patient was 2545 cm(2). Complete healing was achieved in 6.4 days.

CONCLUSION

The CAlloK allow rapid healing of STSG donor-sites and deep 2nd second degree burns in extensively burned patients.

Keratinocytes in the treatment of severe burn injury: an update

Burns are among the most life-threatening physical injuries, in which fast wound closure is crucial. The surgical burn care has evolved considerably throughout the past decennia resulting in a shift of therapeutic goals. Therapies aiming to provide coverage of the burn have been replaced by treatments that have both functional as aesthetic outcomes. The standard in treating severe burns is still early excision followed by skin grafting. The use of cultured keratinocytes to cover extensive burn wounds appeared very promising at first, but the technique still has several limitations of which the long time to culture, the major costs, the risk of infection and the need for an adequate dermal layer limit clinical application. The introduction of dermal substitutes, composite grafts, tissue engineering based on stem cell application have been advocated. The aim of this review is to assess the use of cultured keratinocytes in terms of technical aspects, clinical application, limitations and future perspectives. Cultured keratinocytes are expected to keep playing a role in wound healing, especially in the field of chronic wounds. In severe burns, despite its limitations, keratinocytes can be beneficial if implemented as one of the elements in a broader wound management.

Feeder layer- and animal product-free culture of neonatal foreskin keratinocytes: improved performance, usability, quality and safety

Since 1987, keratinocytes have been cultured at the Queen Astrid Military Hospital. These keratinocytes have been used routinely as auto and allografts on more than 1,000 patients, primarily to accelerate the healing of burns and chronic wounds. Initially the method of Rheinwald and Green was used to prepare cultured epithelial autografts, starting from skin samples from burn patients and using animal-derived feeder layers and media containing animal-derived products. More recently we systematically optimised our production system to accommodate scientific advances and legal changes. An important step was the removal of the mouse fibroblast feeder layer from the cell culture system. Thereafter we introduced neonatal foreskin keratinocytes (NFK) as source of cultured epithelial allografts, which significantly increased the consistency and the reliability of our cell production. NFK master and working cell banks were established, which were extensively screened and characterised. An ISO 9001 certified Quality Management System (QMS) governs all aspects of testing, validation and traceability. Finally, as far as possible, animal components were systematically removed from the cell culture environment. Today, quality controlled allograft production batches are routine and, due to efficient cryopreservation, stocks are created for off-the-shelf use. These optimisations have significantly increased the performance, usability, quality and safety of our allografts. This paper describes, in detail, our current cryopreserved allograft production process.

A randomized trial comparing ReCell system of epidermal cells delivery versus classic skin grafts for the treatment of deep partial thickness burns

BACKGROUND

Our purpose was to directly compare results obtained with the ReCell system and the classic skin grafting for epidermal replacement in deep partial thickness burns.

MATERIALS AND METHODS

We recruited all patients with deep partial thickness burns admitted at the Burn Centre of S. Eugenio Hospital in Rome over 2 years. Enrollment was conducted with a controlled strategy--sampling chart--that allowed homogeneous groups (ReCell and skin grafting) for age, gender, type of burns and total burn surface area (TBSA). We evaluated as primary endpoints of the study the (i) time for complete epithelization (both treated area and biopsy site) and (ii) aesthetic and functional quality of the epithelization (color, joint contractures). Secondary endpoints were the assessment of infections, inflammations or any adverse effects of the ReCell procedure, particular medications assumed, postoperative pain.

RESULTS

Eighty-two patients were analyzed in two homogeneous groups. All of them received adequate epidermal replacement, but skin grafting was faster than ReCell (p<0.05). On the contrary, ReCell biopsy areas and postoperative pain were smaller than classic grafting (p<0.05). The aesthetic and functional outcomes were similar between procedures.

CONCLUSIONS

ReCell is a feasible, simple and safe technique. It gives similar results to skin grafting but, harvesting minor areas, can open possible future applications in the management of large-burns patients.

Evaluation of the biocompatibility of acellular porcine dermis

The biocompatibility of an acellular porcine dermis was evaluated by in vitro methods. Endothelia cells (ECV-304) and fibroblasts (NIH-3T3) were seeded on the dermis and cultured for 1 week to assess the cell viability in the skin grafts. Results by morphological assessment and methylthiazolyl tetrazolium assay (MTT assay) indicated good biocompatibility of acellular porcine dermis, which allowed adhesion and proliferation of examined cell types. Flow chamber technique was used to evaluate the adhesive force between cells and biomaterials. There was no significant difference in cells retention ratio between control cells and experimental cells after sheared 24h. The determination of integrin alpha5 expression proved that the acellular porcine dermis did not influence the expression of integrin alpha5 in cells. The results suggested that the dermal equivalent made from pigskin is a promising material for burn treatment.

Evaluation of decellularized esophagus as a scaffold for cultured esophageal epithelial cells

Recently, decellularized tissue has been reported to have the potential to regenerate a variety of tissues. However, the optimal protocol for a decellularized esophagus has not been studied. Here, we investigated the effect of different decellularization protocols on the histology and biocompatibility of decellularized esophagi in view of future applications to tissue engineering. The esophageal mucosal epithelium (EP) from 4-week-old Wistar rats was enzymatically dissociated and cultured with growth-arrested feeder cells. Two methods for decellularization using deoxycholic acid (DEOX) or Triton X-100 (TRITON) were compared on esophagi from adult Wistar rats. Those treated with DEOX showed superior mechanical properties, maintenance of extracellular matrix, and lower DNA content than those treated with TRITON. To evaluate the biocompatibility of the scaffold, cultured (passage 3) esophageal epithelial cells were seeded inside the decellularized esophagus and cultured for 7 days. The cells seeded onto the decellularized esophagus were examined histologically and immunocytochemically. Esophageal epithelial cells were stratified into three to four cellular layers in vitro inside the decellularized esophagus, to show polarity. The results from immunocytochemistry indicated that the seeded epithelial cells expressed characteristic marker proteins for native esophageal EP. Decellularized esophagus showed suitable compatibility as a scaffold material for esophageal tissue engineering.

Sprayed Cultured Epithelial Autografts for Deep Dermal Burns of the Face and Neck

The objective of this study was the assessment of clinical results after sprayed application of cultured epithelial autograft (CEA) suspensions onto deep dermal burn wounds of the face and neck. Nineteen patients with deep dermal burns of the face and neck were included into a prospective study. The average total body surface area burn was 15.1% (7%-46%; median: 13%). The average Abbreviated Burn Severity Index (ABSI) was 6.7 points (4-12 points; median: 7 points). The application of sprayed CEA suspension was performed onto an average body surface area of 2% (0.5-5%; median: 2%). Thirteen patients were recruited for clinical follow-up after an average of 10 months (3-18 months). The average Vancouver Scar Scale score at follow-up was 2.4 +/- 2.2 points (range, 0-8 points), and the average Donnersmarck and Hörbrand score was 9.3 +/- 6.8 points (range, 0-22). Four patients had less than 9 months' follow-up. Excluding these patients from the analysis resulted in an average Vancouver Scar Scale score of 1.3 +/- 0.9 points (range, 0-3 points) and an average Donnersmarck and Hörbrand score of 8.0 +/- 7.4 points (range 0-22) for the remaining 9 patients.Our data show that enzymatic and careful surgical debridement and consecutive application of CEA suspensions using a spray technique results in excellent cosmetic outcomes compared with any other method.

The possibility of long-term cryopreservation of cultured dermal substitute

Allogeneic cultured dermal substitute (CDS) was prepared by cultivating fibroblasts on a two-layered spongy matrix of hyaluronic acid (HA) and atelo-collagen (Col). CDS can be cryopreserved and transported to other hospitals in a frozen state. To evaluate cell viability, cell growth, and release of VEGF after long-term cryopreservation, the CDS was cryopreserved at -85 degrees C or -152 degrees C for a given period. We measured cell viability immediately after thawing and cell growth in CDS that was recultured for 1 week after thawing. In addition, the amount of vascular endothelial growth factor (VEGF) released from CDS that was recultured for 1 week after thawing was measured. The cell viability and cell growth of control CDS that was thawed within 3 weeks after freezing was 56.2% and 132.7%, respectively. The cell viability and cell growth of the CDS that was cryopreserved at -85 degrees C for 6 months was 43.4% and 119.7%, respectively. When cryopreserved at -152 degrees C for 1 year, the cell viability and cell growth was 52.0% and 110.8%, respectively. These values were comparable to those of the control. The amount of VEGF released from CDS cryopreserved at -85 degrees C for 6 months (491.0 pg/mL) or at -152 degrees C for 1 year (586.8 pg/mL) was comparable to that of the control CDS (587.3 pg/mL). In contrast, the amounts of VEGF released from CDS cryopreserved at -85 degrees C for 1 year (322.5 pg/mL) or at -152 degrees C for 2 years (210.8 pg/mL) were low, with a marked decrease in cell viability and cell growth. These findings suggest that CDS cryopreserved at -85 degrees C for 6 months or at -152 degrees C for 1 year maintains sufficient cell viability and the ability to proliferate and release a significant amount of VEGF. The release of VEGF from CDS after long-term cryopreservation is a useful therapeutic effect, and is important for clinical use.

Les substituts cutanés reconstruits en laboratoire : application au traitement des brûlés

The development of skin substitutes started 25 years ago with the cultivation of keratinocytes to replace the epidermis of extensively burned patients. It is now possible to reproduce in vitro the two layers of skin, epidermis and dermis. Cultured epidermises are now usually used in burn centers dealing with the more severe patients. They are provided by hospital or private laboratories. Dermal substrates are some collagen matrices, which act in vivo as a guide for the reconstruction of a neodermis. Living dermis include living fibroblasts. Different models are now available for clinical use. Living skin equivalent is obtained by coculturing fibroblast and keratinocytes on a collagen support. Clinical essays are going on for chronic wounds. We present the different skin equivalent models and their clinical applications.

Treatment of second degree facial burns with allografts—preliminary results

Facial burns are very common and have significant clinical impact. However, the treatment regimen for superficial to deep facial burns is not well defined. The purpose of this study was to investigate the effects of cadaver skin grafting in deep partial thickness facial burns in comparison to standard care. In a prospective open study design severely injured patients with superficial and deep partial thickness burns were randomized into the group receiving open treatment with silversulfadiazine (standard n=5) or into the group receiving early superficial debridement followed by coverage with glycerolized cadaver skin (n=5). The outcome measures were time and quality of wound healing, and incidence of hypertrophic scarring at 3 and 6 months post burn. There were no significant differences in demographics between groups. In the group treated with the allogenic material time to reepithelialization was 10.5 days, while it was 12.4 days in the silversulfadiazine group (p<0.05). Scar quality was found to be significantly improved in the allogenic treatment group. Three and 6 months postburn there were no patients with significant hypertrophic scarring in the allogenic group while there were two patients who developed hypertrophic scars in the silversulfadiazine group (p<0.05). In this study, we demonstrated that glyzerolized cadaver allograft skin represents a superior biological dressing for shallow and deep partial thickness facial burns. This is in concordance with other reports on scalds. It would be worthwhile to perform more clinical studies with a larger number of patients to further evaluate the effect and function of allogenic skin for facial burns.

Should dermal scald burns in children be covered with autologous skin grafts or with allogeneic cultivated keratinocytes?--"The Viennese concept"

The treatment of scald burns in children is still under discussion. The aim of the present study was to evaluate an optimised treatment regime for scald burns in children. Between 1997 and 2002, 124 children underwent surgical intervention due to burn injuries. Thirty-six out of these 124 children were enrolled into the evaluation of our recent treatment protocol. Twenty-two children with scald burns covering an average body surface area (TBSA) of 18.5% were treated by early excision and coverage with allogeneic keratinocytes in case of partial thickness lesions (keratinocyte group). Fourteen children with a TBSA of 17.2% were treated with autologous skin grafts alone (skin graft group). Both groups were comparable according to age, burn depth and affected TBSA. The complete clinical follow-up examination of at least 17 months was performed in 12 out of 22 children of the keratinocyte group and in 9 out of 14 patients of the comparative group. Visible scar formations were classified according to the Vancouver Scar Scale (VSS) in each patient. The use of allogeneic keratinocytes led to complete epithelialisation within 12 days in 20 of the 22 cases. No secondary skin grafting procedures had to be done. Skin take rate at the sixth postoperative day was 100% in the skin graft group. Blood transfusions were administered intraoperatively according to the clinical need of the patients by the responsible anaesthesiologist. The mean volume of blood, which had to be transfused was 63.9 ml in the keratinocyte group and significantly lower than the volume of 151.4 ml, which was administered in the skin graft group (p=0.04). At follow up the VSS observed in areas covered by keratinocytes was 2.33 on the average and therefore, significantly lower than the VSS of 5.22 in skin grafted areas of the comparative group (p=0.04). In children the use of cultivated keratinocytes in partial thickness scald burns is a procedure, which renders constantly reliable results. It minimizes the areas of autologous skin harvesting and reduces the amount of blood transfusions. The fact that less scarring is observed after keratinocyte grafting leads to the conclusion that skin grafting in children should be restricted to scalded areas, which have to be excised to the subcutaneous fat tissue.