Skin donors and human skin allografts: evaluation of an 11-year practice and discard in a referral tissue bank

3D skin bioprinting as promising therapeutic strategy for radiation-associated skin injuries

Both cutaneous radiation injury and radiation combined injury (RCI) could have serious skin traumas, which are collectively referred to as radiation-associated skin injuries in this paper. These two types of skin injuries require special managements of wounds, and the therapeutic effects still need to be further improved. Cutaneous radiation injuries are common in both radiotherapy patients and victims of radioactive source accidents, which could lead to skin necrosis and ulcers in serious conditions. At present, there are still many challenges in management of cutaneous radiation injuries including early diagnosis, lesion assessment, and treatment prognosis. Radiation combined injuries are special and important issues in severe nuclear accidents, which often accompanied by serious skin traumas. Mass victims of RCI would be the focus of public health concern. Three-dimensional (3D) bioprinting, as a versatile and favourable technique, offers effective approaches to fabricate biomimetic architectures with bioactivity, which provides potentials for resolve the challenges in treating radiation-associated skin injuries. Combining with the cutting-edge advances in 3D skin bioprinting, the authors analyse the damage characteristics of skin wounds in both cutaneous radiation injury and RCI and look forward to the potential value of 3D skin bioprinting for the treatments of radiation-associated skin injuries.

Organization of Hannover Skin Bank: Sterile culture and procurement protocols for viable cryopreserved allogeneic skin grafts of living donors

Preserved allogeneic donor skin still represents one of the gold standard therapies in temporary wound coverage in severely burned patients or chronic wounds. Allogeneic skin grafts are currently commercially available as cryo- or glycerol-preserved allografts through skin tissue banks all over the world. Most of the skin tissue banks rely on human cadaveric skin donations. Due to the chronic shortage of human allogeneic transplants, such as skin, and increasing costs in the procurement of allografts from other skin tissue banks, Hannover Medical School has been building up its own skin tissue bank based on allogeneic skin grafts from living donors who underwent surgical treatment (i.e., body-contouring procedures, such as abdominioplasties). This article presents procedures and protocols for the procurement and processing of allogeneic skin grafts according to national legislation and European regulations and guidelines. Beside protocols, initial microbiological data regarding the sterility of the harvested grafts are presented. The results currently form the basis for further investigations as well as clinical applications. In summary, a microbiological testing and acceptance procedure is presented that ensures adequate patient safety and skin viability.

Human skin processing affects clinical outcome in allograft recipients

Skin allografts represent a milestone in burn patient treatment. However, skin procurement is still burdened by high rates of contamination, and validation procedures have not yet been standardized. In addition, it is not clear if tissue viability affects allograft skin outcomes. In 2120 skin samples from 610 donors, a retrospective analysis was performed to identify donor and procurement variables associated with bacterial contamination and tissue viability. Post-processing contamination was associated significantly with the donor type, cause of death, length of hospitalization, procurement site, surgeon, interval between procurement and banking, and decontamination method. Tissue viability appeared to be negatively associated with freezing. In two series of skin allograft recipients (155 and 195 patients), we evaluated the role of skin characteristics and procurement variables on clinical outcomes. We found that the length of hospitalization was associated significantly with donor age. Procalcitonin and PCR values in allograft recipients were correlated with the decontamination method. No significant associations were observed between tissue viability and clinical outcomes (length of hospitalization, cause of donor death, or inflammatory parameters) after allograft transplantation. In these large case series, we identified donor and procurement variables that may affect allograft skin recipients. The decontamination method appeared to be a critical step for skin allograft requiring better standardization.

Biofilm formation and antibiotic susceptibility of Staphylococcus and Bacillus species isolated from human allogeneic skin

Human skin banks around the world face a serious problem with the high number of allogeneic skins that are discarded and cannot be used for grafting due to persistent bacterial contamination even after antibiotic treatment. The biofilm formation capacity of these microorganisms may contribute to the antibiotic tolerance; however, this is not yet widely discussed in the literature. Thisstudy analyzed bacterial strains isolated from allogeneic human skin samples,which were obtained from a hospital skin bank that had already been discardeddue to microbial contamination. Biofilm formation and susceptibility topenicillin, tetracycline, and gentamicin were evaluated by crystal violetbiomass quantification and determination of the minimum inhibitoryconcentration (MIC), minimum biofilm inhibitory concentration (MBIC), andminimum biofilm eradication concentration (MBEC) by the broth microdilutionmethod with resazurin dye. A total of 216 bacterial strains were evaluated, and204 (94.45%) of them were classified as biofilm formers with varying degrees ofadhesion. MBICs were at least 512 times higher than MICs, and MBECs were atleast 512 times higher than MBICs. Thus, the presence of biofilm in allogeneicskin likely contributes to the inefficiency of the applied treatments as antibiotictolerance is known to be much higher when bacteria are in the biofilmconformation. Thus, antibiotic treatment protocols in skin banks shouldconsider biofilm formation and should include compounds with antibiofilmaction.

Clinical Applications of Allograft Skin in Burn Care

Allograft skin has been widely used for wound management in burn centers. Functional as biologic dressing, it can not only provide ideal temporary wound coverage in extensive burns when autograft is not immediately available but also prepare the wound bed for definitive autografting. In this article, the up-to-date clinical application of allograft in burn care was reviewed, including coverage of extensive burn wounds, combined use with meshed autograft, template for delayed application of cultured epidermal autografts, and the use of human acellular dermal matrix. Although it has potential disadvantages of rejection and disease transmission, allograft skin remains a workhorse in treatment of severe burn wounds.

Glycerolised skin allografts for extensive burns in low- and middle-income countries

Introduction:

There has been a significant improvement in the outcome of treatment of large surface area burns in developed countries. A major contributory factor is an early excision and skin grafting of burn wounds. The initial coverage of large surface area deep burn wounds requires the use of temporary skin substitutes such as allografts due to limited skin autografts. Cadaveric skin allografts are the commonest source of skin allografts in use; however, there may be religious, cultural, cost, or other factors mitigating its availability and routine use in low- and middle-income countries (LMICs). Human skin allografts may be used fresh or stored in tissue banks to ensure its ready availability. The purpose of this review is to promote glycerolised skin allografts as a means of skin preservation in low-resource countries above other modalities cryopreservation due to its cost advantages and relative ease of operation.

Materials and Methods:

A literature search for articles related to human skin allograft use in burn care, skin banks, and glycerolised skin allografts in LMICs was done using PubMed, EMBASE, and Web of Science databases. The key words used were ‘allograft’ and ‘burn’ with a filter in the search for human studies. The relevant references in the articles obtained were also searched for and included in the review

Results:

Sixty-three journal articles were reviewed for contents in line with the objectives of this study.

Conclusion:

Glycerolised skin graft is a viable option for coverage of extensive burns in LMICs.

How to improve donor skin availability: Pragmatic procedures to minimize the discard rate of cryopreserved allografts in skin banking

BACKGROUND

Microbial contamination of human skin allografts is a frequent cause of allograft discard. Our purpose was to evaluate the discard rate of skin bank contaminated allografts and specific procedures used to reduce allograft contamination without affecting safety.

METHODS

We conducted at the Lille Tissue Bank a retrospective study of all deceased donors (n = 104) harvested from January 2018 to December 2018. Skin procurement was split into 3 zones: the back of the body and the two legs that were processed separately. It represented 433 cryopreserved skin allograft pouches of approximatively 500 cm² each. Donors were almost equally split between brain-dead (53%, 55/104) and cadaveric (47%, 49/104) donors.

RESULTS

Out of all donors, 42 (40.5%) had at least one sampling zone with a positive microbiological test resulting in 106 (24%) contaminated skin pouches. The contamination rate did not vary according to the harvested zone or type of donor. Traumatic deaths showed significantly less contamination rates than other death types (p < 0.05). Contamination rate decreased with time spent in the antibiotic solution. The risk of having contaminated allografts was five-fold higher when the skin spent less than 96 h in the antibiotic cocktail (p < 0.05). According to our validation protocol, most donors (32/42, 76%) had skin allografts contaminated with bacteria (mainly Staphylococcus spp) compatible with clinical use. No recipient infection was recorded as a result of skin graft contaminated with saprophytic or non-pathogenic germs. By harvesting 3 separate zones per donor, the total surface area for clinical use increased by 53% for contaminated donors. Overall, the proportion of contamination-related discarded allografts was 3.2% (14/433 of pouches).

CONCLUSION

Few simple pragmatic measures (including skin incubation in the antibiotic bath for at least 96 h at 4 °C, splitting the skin harvesting areas to minimize the risk of cross-infection and clinical use of allografts contaminated with saprophytic and non-pathogenic germs) can reduce the discard rate of contaminated allografts without affecting clinical safety.

A clinical-grade acellular matrix for esophageal replacement

In pathologies of the esophagus such as esophageal atresia, cancers, and caustic injuries, methods for full thickness esophageal replacement require the sacrifice of healthy intra-abdominal organs such as the stomach and the colon and are associated with high morbidity, mortality, and poor functional results. To overcome these problems, tissue engineering methods are developed to create a substitute with scaffolds and cells. The aim of this study was to develop a simple and safe decellularization process in order to obtain a clinical grade esophageal extracellular matrix. Following the decontamination step, porcine esophagi were decellularized in a bioreactor with sodium dodecyl sulfate and ethylenediaminetetraacetic acid for 3 days and were rinsed with deionized water. DNA was eliminated by a 3-hr DNase treatment. To remove any residual detergent, the matrix was then incubated with an absorbing resin. The resulting porcine esophageal matrix was characterized by the assessment of the efficiency of the decellularization process (DNA quantification), evaluation of sterility and absence of cytotoxicity, and its composition and biomechanical properties, as well as the possibility to be reseeded with mesenchymal stem cells. Complete decellularization with the preservation of the general structure, composition, and biomechanical properties of the native esophageal matrix was obtained. Sterility was maintained throughout the process, and the matrix showed no cytotoxicity. The resulting matrix met clinical grade criteria and was successfully reseeded with mesenchymal stem cells..

Bacterial contamination of human skin allografts and antimicrobial resistance: a skin bank problem

Background

Bacterial contamination remains the major problem in skin banks, even after antimicrobial treatment, and results in high rates of tissue discarding. This study aimed to analyze bacterial contamination in 32 human skin allografts from the skin bank of Dr. Roberto Corrêa Chem from the Hospital Complex Santa Casa de Misericórdia de Porto Alegre. These samples were already discarded due to microbial contamination. The identification of the bacteria isolated from skin allografts was performed by matrix assisted laser desorption ionization–time of flight. The antimicrobial susceptibility of the isolates to six different classes of antimicrobials was determined using the disk-diffusion agar method, and the evaluation of the inhibitory potential was determined by the minimal inhibitory concentration (50/90) of antimicrobials already used in the skin bank and those that most isolates were susceptible to.

Results

A total of 21 (65.6%) skin samples were contaminated with Gram-positive bacteria: 1 (4.7%) with Paenibacillus sp., 12 (61.9%) with Bacillus sp., 6 (28.5%) with Staphylococcus sp., and 2 (9.5%) with Bacillus sp. and Staphylococcus sp. Several resistance profiles, including multiresistance, were found among the isolates. Most of the isolates were susceptible to at least one of the antimicrobials used in the skin bank. All isolates were susceptible to amikacin, gentamicin, and tetracycline, which demonstrated the best inhibitory activities against the isolates and were considered as potential candidates for new antimicrobial treatments.

Conclusions

Bacillus, Paenibacillus, and Staphylococcus were isolated from the skin allografts, thus demonstrating the predominance of Gram-positive bacteria contamination. Other factors not related to the resistance phenotype may also be involved in the persistence of bacterial isolates in the skin allografts after antibiotic treatment. Gentamicin, amikacin, and tetracycline can be considered as an option for a more effective treatment cocktail.

Electronic supplementary material

The online version of this article (10.1186/s12866-018-1261-1) contains supplementary material, which is available to authorized users.