Expansion technique for skin grafts (Meek technique) in the treatment of severely burned patients

Bacterial fluorescence imaging as a predictor of skin graft integration in burn wounds

BACKGROUND

Split-thickness skin graft (STSG)1 integration rates are susceptible to improvement. Infection and/or biofilm should be appropriately addressed prior to grafting to improve the likelihood of graft-take. Incorporating technological aids such as fluorescence (FL)2 imaging (MolecuLight®), which accurately locates areas of bacterial loads above 104 CFU/gr, for graft site assessment and preparation could yield better outcomes.

METHODS

This single-center, prospective observational study included adult burn patients with previously infected wounds that had been deemed clinically and microbiologically clean and were therefore candidates for grafting. Prior to grafting, a FL imaging assessment (blinded to the surgical team) localized areas positive for moderate-high bacterial loads (>104 CFU/gr). Intra-operatively, a standard swab sample from the recipient site was collected by the surgical team. Postoperatively, areas positive/negative for FL and areas of graft take and failure were overlapped and measured (cm2) over a 2D schematic. The performance and accuracy of FL imaging and swab sampling in relation to graft outcomes were assessed.

RESULTS

38 patients were enrolled in the study. The mean total body surface area (TBSA)3 involvement was 14.5 ± 12.4 % [range 0.8 - 40.2 %]. 25/38 of the subjects enrolled had complete graft take while 13 had partial graft losses. There were no total losses. FL-imaging was positive in 100 % of losses versus 31 % (4/13) of the swab microbiology. FL-imaging was found to have a sensitivity of 86 %, specificity of 98 %, PPV of 72 %, NPV of 99 %, and an accuracy of 94 % for predicting any type or range of graft loss in the entire cohort. Meanwhile, the sensitivity of microbiology from swab samples was 30 %, with a specificity of 76 %.

CONCLUSIONS

FL imaging is an accurate method for assessing recipient sites and predicting the outcome of a skin graft among burn patients. These findings suggest that FL imaging can inform better decision-making surrounding grafts that may lead to better outcomes.

LEVEL OF EVIDENCE

Level IIA, Therapeutic study.

Addressing Full-Thickness Skin Defects: A Review of Clinically Available Autologous Skin Replacements

Autologous keratinocyte culture, and combinations of scaffolds, different cell types, solutions of macromolecules, or growth factors have contributed to the resurfacing of full-thickness skin defects. Ideally, a treatment for full-thickness skin defects should not merely reestablish continuity of the surface of the skin but should restore its structure to allow skin to function as a dynamic biological factory that can participate in protein synthesis, metabolism, and cell signaling, and form an essential part of the body's immune, nervous, and endocrine systems. This paper provides a review of clinically available autologous skin replacements, highlighting the importance of regenerating an organ that will function physiologically.

Historical Evolution of Skin Grafting-A Journey through Time

Autologous skin grafting was developed more than 3500 years ago. Several approaches and techniques have been discovered and established in burn care since then. Great achievements were made during the 19th and 20th century. Many of these techniques are still part of the surgical burn care. Today, autologous skin grafting is still considered to be the gold standard for burn wound coverage. The present paper gives an overview about the evolution of skin grafting and its usage in burn care nowadays.

Novel application of autologous micrografts in a collagen-glycosaminoglycan scaffold for diabetic wound healing

BACKGROUND

Therapeutic strategies that successfully combine two techniques-autologous micrografting and biodegradable scaffolds-offer great potential for improved wound repair and decreased scarring. In this study we evaluate the efficacy of a novel modification of a collagen-glycosaminoglycan scaffold with autologous micrografts using a murine dorsal wound model.

METHODS

db/db mice underwent dorsal wound excision and were treated with a collagen-glycosaminoglycan scaffold (CGS), a modified collagen-glycosaminoglycan scaffold (CGS+MG) or simple occlusive dressing (Blank). The modified scaffold was created by harvesting full thickness micrografts and transplanting these into the collagen-glycosaminoglycan membrane. Parameters of wound healing, including cellular proliferation, collagen deposition, keratinocyte migration, and angiogenesis were assessed.

RESULTS

The group treated with the micrograft-modified scaffold healed at a faster rate, showed greater cellular proliferation, collagen deposition, and keratinocyte migration with higher density and greater maturity of microvessels. The grafts remained viable within the scaffold with no evidence of rejection. Keratinocytes were shown to migrate from the wound border and from the micrograft edges towards the center of the wound, while cellular proliferation was present both at the wound border and wound bed.

CONCLUSION

We report successful treatment of diabetic wounds with a novel collagen-glycosaminoglycan scaffold modified with full-thickness automicrografts. Differences in cellular migration and proliferation offer maiden evidence on the mechanisms of wound healing. Clinically, the successful scaffold engraftment, micrograft viability and improved wound healing offer promising results for the development of a new therapeutic modality for wound repair.

Comparison of Modified Meek Technique with Standard Mesh Method in Patients with Third Degree Burns

BACKGROUND

Covering burn wounds, especially high surface area burns has been always a challenge for surgeons. The Meek technique has been introduced to increase the covering area. There is paucity of clinical trials comparing the Meek technique and mesh in the same individuals to assess it efficacy.

METHODS

In a case-control study, 20 patients with grade III burns who underwent the Meek technique and mesh in different areas/limbs were enrolled. Expansion rate, re-epithelization, operation time, wound infection, graft failure, etc. were compared between the two groups.

RESULTS

Among patients, 18 were males and 2 were females. The mean of total body surface area (TBSA) was 36.9±16.6%. Mean time of re-epithelialization in the Meek group was 2.8±2.5 months and in the mesh group was 5.0±2.1 months (p=0.01). Operation time was shorter in modified Meek technique (p=0.04). Expansion ratio was higher in modified Meek technique (p=0.04). Local wound infection rates were slightly different without a statistically significant difference.

CONCLUSION

Meek technique provided higher surface area coverage in comparison to mesh; in addition to faster re-epithelization. Therefore, it is recommended to consider the Meek technique as a routine procedure, especially those with high surface area burns.

Simple limbal epithelial transplantation (SLET): Review of indications, surgical technique, mechanism, outcomes, limitations, and impact

Simple limbal epithelial transplantation (SLET) is an innovative limbal stem cell transplantation technique that has gained increasing popularity over the last few years. Different groups from across the world have published the clinical results of SLET in large case series with varying types and severities of limbal stem cell deficiency (LSCD). This review attempts to place all the available knowledge on SLET together in one place for the benefit of not only cornea specialists and trainees but also for residents and general ophthalmologists. It follows a balanced approach of blending evidence with experience by providing an objective analysis of published results along with helpful insights from subject experts, starting from preoperative considerations including the role of newer imaging modalities to the technical aspects of the surgery itself and the management of possible complications. Original data and novel insights on allogeneic SLET for bilateral LSCD are included in the review to address the few remaining lacunae in the existing literature on this topic. This review intends to inform, educate, and empower all aspiring and practicing SLET surgeons to optimize their clinical outcomes and to have maximal positive impact on the lives of the individuals affected by unilateral or bilateral chronic LSCD.

Outcome of the Modified Meek Technique in the Management of Major Pediatric Burns

INTRODUCTION

The modified Meek micrografting technique has been used in the treatment of severely burned patients and a number of articles have examined the use of the modified Meek technique in adults and in mixed-age groups. However, there is a paucity of research pertaining to the outcome in the pediatric age group. The aim of this study is to present our favorable outcome in pediatric major burns using the modified Meek technique.

METHODS

A retrospective review of burn cases in Hospital Universiti Sains Malaysia from 2010 to 2015 was conducted. Cases of major burns among pediatric patients grafted using the Meek technique were examined.

RESULTS

Twelve patients were grafted using the Meek technique. Ten (91.7%) patients were male, whereas 2 (8.3%) were female. The average age of patients was 6 years (range, 2-11 years). The average total body surface area was 35.4% (range, 15%-75%). Most burn mechanisms were due to flame injury (66.7%) as compared with scalds injury (16.7%) and chemical injury (16.7%). There was no mortality. All patients were completely grafted with a good donor site scar. The average graft take rate was 82.3%, although 8 cases had positive tissue cultures from the Meek-grafted areas. The average follow-up duration was 3.6 years (range, 1.1-6.7 years). Only 1 case developed contracture over minor joint.

CONCLUSIONS

The Meek technique is useful when there is a paucity of donor site in the pediatric group. The graft take is good, contracture formation is low, and this technique is cost-effective.

Meek micrografting history, indications, technique, physiology and experience: a review article

AIMS

Traumatic loss of skin, particularly in major burns, requires skin grafting to repair the tissue. For a large burn, where donor sites are limited, the skin graft may need to be expanded. In addition, rapid wound closure is a large factor in successful recovery and is usually achieved by debridement and skin grafting. Micrografting was introduced by Meek and involved dividing the skin into small pieces, allowing for up to a tenfold skin expansion.

METHODS

We conducted a review of the literature, searched via Medline, Pubmed and Embase (from 1958 to June 2017), searching to identify studies and reports of micrografting. We searched using the Medical Subject Headings (MeSH) 'micrograft', 'micrograft technique', 'Meek', 'Meek technique', 'Parker Cicero', 'major burn treatment' and 'mesh skin graft'.

RESULTS

We analysed 24 articles in which the description and modifications presented by the micrograft technique were presented, along with evidence that supports or rejects its use. The consensus was for the use of micrografting in burns of >30% total body surface area (TBSA). On poor wound beds, the evaluation of re-epithelialisation had greater success due to low metabolic demands and greater skin coverage compared with control groups (p<0.005). Comparing the 'mesh' with 'Meek' group, the micrograft group had fewer surgeries (10 versus 19.75), shorter average length of hospital stay (51 days versus 120.5 days; p<0.05).

CONCLUSIONS

Micrografting can be used where there is poor bed vascularity (such as in patients with diabetes), with higher success due to low metabolic demand. This is recommended for major burns, >30% TBSA, with inadequate donor sites and comorbidities, such as diabetes. However, disadvantages include a 'polka dot' appearance on healing and the fact the initial surgeries, creating the micrograft squares, are labour-intensive.

Skin bioprinting: the future of burn wound reconstruction?

Burns are a significant cause of trauma, and over the years, the focus of patient care has shifted from just survival to facilitation of improved functional outcomes. Typically, burn treatment, especially in the case of extensive burn injuries, involves surgical excision of injured skin and reconstruction of the burn injury with the aid of skin substitutes. Conventional skin substitutes do not contain all skin cell types and do not facilitate recapitulation of native skin physiology. Three-dimensional (3D) bioprinting for reconstruction of burn injuries involves layer-by-layer deposition of cells along with scaffolding materials over the injured areas. Skin bioprinting can be done either in situ or in vitro. Both these approaches are similar except for the site of printing and tissue maturation. There are technological and regulatory challenges that need to be overcome for clinical translation of bioprinted skin for burn reconstruction. However, the use of bioprinting for skin reconstruction following burns is promising; bioprinting will enable accurate placement of cell types and precise and reproducible fabrication of constructs to replace the injured or damaged sites. Overall, 3D bioprinting is a very transformative technology, and its use for wound reconstruction will lead to a paradigm shift in patient outcomes. In this review, we aim to introduce bioprinting, the different stages involved, in vitro and in vivo skin bioprinting, and the various clinical and regulatory challenges in adoption of this technology.

Five Years Experience With Meek Grafting in the Management of Extensive Burns in an Adult Burn Center

Background

In extensive burn injuries with lack of donor sites for skin grafting, the Meek technique of skin expansion can be an efficient and effective method in covering extensive wounds. The aim of this retrospective study was to present our experience with the Meek technique of grafting.

Methods

We performed a retrospective analysis of patients from our burn center who underwent Meek grafting between 2012 and 2016. Demographics, burn details, clinical course, operative management, and outcomes were collected and analyzed from patient records and operative notes. Outcome measures, including graft take rate, complications and need for further surgery, were recorded.

Results

Twelve patients had Meek grafting. The average age was 38 years (range: 15-66). The average percent total body surface area burned was 54.3% (range: 31%-77%). Eighty-three percent of grafted areas healed well, and no regrafting was necessary. In the remaining 17%, infection and hematoma were the leading cause of graft failure.

Conclusions

Meek grafting constitutes a rapid and efficient surgical approach for the skin coverage of extensive full-thickness burn injuries with limited autograft donor sites.

Response of a local hospital to a burn disaster: Contributory factors leading to zero mortality outcomes

OBJECTIVE

To investigate the outcomes of a local healthcare system in managing a burn mass casualty incident (BMCI).

METHODS

Thirty-three victims admitted to the National Taiwan University Hospital within 96h of the explosion were included in the study. Data were recorded on: patient demographics, Baux score, laboratory data, management response, treatment strategies, and outcomes. Case notes from June 27, 2015 to November 2015 were reviewed with a focus on fluid resuscitation, ventilation support, nutrition, infection control, sepsis treatment, and wound closure plan.

RESULTS

Female predominance (mean age: 21.7 years) and lower extremity circumferential flame burns were the characteristics of the burn injury. The mean Baux score was 70±18. The mean burn area was 42% of the total body surface area (TBSA). A total of 79% patients arrived at the hospital within 24h of sustaining injuries. Intensive care unit (ICU) admission criteria were modified to accommodate patients with 40% TBSA of burns, facilities were expanded from 4 ICU beds to 18 beds, and new staff was recruited. A total of 36% patients (n=12/33, 62±13 TBSA of burns) required fluid resuscitation. The mean volume of Lactate Ringer administered in the first 24h of burns was 3.34±2.18ml/kg/%TBSA, while the mean volume of fresh frozen plasma administered was 0.60±0.63ml/kg/h. Forty-two percent patients were intubated on the day of admission, and 71% of the intubated patients had inhalation injuries that were confirmed by diagnostic bronchoscopy. The mean intubation period was 17±9 days. The incidence of pulmonary edema was 58% (n=7/12), possibly due to sub-optimal monitoring. Of these, 57% (n=4/7) patients progressed to adult respiratory distress syndrome, but were successfully treated with early strict fluid restriction, systemic antibiotics, ventilation support, and bronchial lavage. A total of 94% patients received grafting. The mean grafted area was 4432.3±3891cm². Tube feeding was provided to patients with burns >40% TBSA. All patients tolerated gastric tube feeding without conversion to duodenal switch. On admission, all patients received prophylactic antibiotics. Septic shock was noted in 12 patients, but no mortality occurred. The mean hospital stay was 1.5 days per percent burn.

CONCLUSIONS

This article highlights the value of precise triage, traffic control, and effective resource allocation in treating a BMCI. Effective supporting systems for facility expansion, staff recruitment, medical supplies and clear-cut treatment strategies for severely burned patients are contributory factors leading to zero mortalities in our series, in addition to young age and minimal inhalation injuries. The need for reevaluation of the safety of cornstarch powder in festival activities is clear.

Scalp as a donor site in children: Is it really the best option?

BACKGROUND

Since 2003 we have used the scalp as a donor site for split skin grafts (SSGs) in major burns when there was a shortage of conventional donor areas. However, we seen a high incidence of complications, contrary to international experience.

OBJECTIVE

The aim of this study was to analyze the results and complications related to the scalp as a donor site and to determine whether there is an association between our specific patient population and the complications encountered.

METHODS

A retrospective review of our scalp donor site outcomes over a 12-year period was conducted. The cohort included 25 patients, 15 of black African descent, nine of mixed race and one Caucasian. The various hair types were identified based on ethnicity and classified into eight types. Most of our patients had hair types VI-VIII. None of these patients had scalp burns and all received standard burn treatment. The SSGs were taken with an electric dermatome with a standard micrometric setting of 0.2mm. Complications were categorized into short- or long-term, with a mean follow-up time of 1.59years.

RESULTS

The mean age of the 25 children was 5.7years. Nineteen sustained flame burns and 6 sustained hot water burns, with a mean total body surface area of 44.9%. A total of 43 scalp procurements were performed in the 25 patients studied. The group of 15 black African patients (hair types VI-VIII) had a total of 22 procurements, the nine patients of mixed race (hair types III-V) had 18 procurements and the single Caucasian patient (hair types II-III) had two procurements. The median healing time was 15days, 11.8days and 8.5days, respectively, per group. Significant complications were encountered, including folliculitis 44%, non-healing wounds 52%, alopecia 16% and visible, hypopigmented scars 3%. One patient had a hypertrophic scar and no hair transfers to the recipient areas were observed. The various hair types correlated with the complications encountered. Five children, with an average burn size of 65.2% (range: 40-85%) died of sepsis. Due to the small sample size, the only statistically significant findings were related to the total body surface area of the burn and the number of times skin was harvested from the scalp, with a p-value of 0.005. The p-values for the healing times related to the first, second and third croppings, were p=0.022, p=0.00032 and p<0.001 respectively.

CONCLUSION

Our study suggests that in pediatric patients of black African descent (hair types VI-VIII) the scalp is not an ideal donor area, due to the unacceptably high incidence of complications. Hence, every precaution should be taken when it becomes necessary to harvest donor skin from the scalp.

The MEEK technique: 10-year experience at a tertiary burn centre

Extensive full-thickness burns pose a great challenge to the burn surgeon. Lack of autograft donor sites is an important limiting factor to achieving wound closure. To overcome this problem, various methods of treatment have been suggested in the past, including the MEEK technique. This study was carried out at the Bogenhausen Hospital Burn Unit, Munich, Germany from 2006 to 2015. There were a total of 148 skin grafting operations. The modified MEEK technique was performed on 67 patients. Patients included 34 males and 33 females, with an average age of 39·6 years. The mean percentage body surface burned was 65%, and full-thickness injury occurred in 52%. The mean area graft per procedure was 20%. The viability of the graft as assessed between the 7th and 10th day was generally in the range of 60-90%. The average number of operations required was 2·21. The mean length of stay was 27 days. Infection was documented in five patients, and seven deaths occurred. The mean follow-up was 3·2 years. When faced with large surface area burns and limited donor sites, the MEEK technique is a satisfactory method for coverage.

Important Developments in Burn Care

LEARNING OBJECTIVES

After studying this article, the participant should be able to: 1. Explain the epidemiology of severe burn injury in the context of socioeconomic status, gender, age, and burn cause. 2. Describe challenges with burn depth evaluation and novel methods of adjunctive assessment. 3. Summarize the survival and functional outcomes of severe burn injury. 4. State strategies of fluid resuscitation, endpoints to guide fluid titration, and sequelae of overresuscitation. 5. Recognize preventative measures of sepsis. 6. Explain intraoperative strategies to improve patient outcomes, including hemostasis, restrictive transfusion, temperature regulation, skin substitutes, and Meek skin grafting. 7. Translate updates in the pathophysiology of hypertrophic scarring into novel methods of clinical management. 8. Discuss the potential role of free tissue transfer in primary and secondary burn reconstruction.

SUMMARY

Management of burn-injured patients is a challenging and unique field for plastic surgeons. Significant advances over the past decade have occurred in resuscitation, burn wound management, sepsis, and reconstruction that have improved outcomes and quality of life after thermal injury. However, as patients with larger burns are resuscitated, an increased risk of nosocomial infections, sepsis, compartment syndromes, and venous thromboembolic phenomena have required adjustments in care to maintain quality of life after injury. This article outlines a number of recent developments in burn care that illustrate the evolution of the field to assist plastic surgeons involved in burn care.

Comparing the Curative Efficacy of Different Skin Grafting Methods for Third-Degree Burn Wounds

Background

Our research purpose was to compare the curative efficacy of different skin grafting methods for treating third-degree burn wounds.

Material/Methods

A total of 105 patients with third-degree burns were involved in this study. The burn wounds of these patients were treated using three different methods: Meek skin grafting, Stamp skin grafting, and Microskin grafting. Patients treated with different methods were placed in different groups. The skin graft survival rate, skin graft fusion time, wound healing time, total time of surgery, and 1% total body surface area (TBSA) treatment costs in each group were evaluated during and after the grafting procedures. After the operations, patients were followed up for 3 to 18 months in order to evaluate the postoperative outcomes.

Results

The skin graft survival rate was significantly higher in the Meek group compared to the rates in the Stamp and Microskin groups (both P<0.01). In addition, the skin graft fusion time, wound healing time, and 1% TBSA treatment costs were significantly lower in the Meek group compared to those in the Stamp and Microskin groups (both P<0.01). Furthermore, the Meek group exhibited better results with respect to curative efficacy, scarring status, and joint activity in comparison to the other two groups (both P<0.05).

Conclusions

The Meek skin grafting method showed better clinical efficacy for treating large wound areas in third-degree burn patients compared to the Stamp and Microskin skin grafting methods.

Experience and outcomes of micrografting for major paediatric burns

BACKGROUND

The deficit of donor sites in major burns over 50% of the total body surface area has necessitated the application of methods besides traditional meshed autografting to achieve definitive skin cover. The Meek micrografting technique was introduced at this hospital in 2011, especially in the absence of a reliable source of deceased donor allograft skin. The purpose of this study was to evaluate this strategy with reference to its technical execution, efficacy and indications in the context of major paediatric burn surgery.

METHODS

A cohort study was performed of all paediatric patients with major burn who underwent Meek micrografting at a dedicated paediatric burn centre in a developing country over a five year period. Demographics, details of their burns, operative management and clinical course and outcomes were collected from patient records and operative notes and analysed.

RESULTS

Thirty-five patients were managed using the micrografting technique during the study period. The mean patient age was 4.1 years (range 3 months-11 years) and their mean total body surface area (TBSA) burn was 49.7% (range 15-86%). Eleven patients sustained inhalation injuries and five developed a re-feeding syndrome on account of delayed referral. The mean abbreviated burn severity index (ABSI) was 8.5 (range 2-13). The hospital length of stay in the 27 survivors was a mean of 75.5 days, equating to 1.4 days per percentage burn. Eight patients died during the course of treatment, with a mean TBSA burn of 67.75% (range 38-86%). Graft take one month after surgery was documented to be more than 90% in 24 patients, of whom 3 subsequently died. Eleven patients had less than 90% graft take at this time, of whom 5 died.

CONCLUSION

There is a considerable 'learning curve' associated with this technique. In order to achieve success one must ensure a completely viable, non-infected bed, obtained by tangential or fascial excision, followed by allografting as temporary coverage and to 'test the wound bed' for definitive coverage. Infection resulted in the majority of autograft loss in this series, and in addition to risk factors like burn size and inhalation injury, accounted for many of the deaths in this series. Meek micrografting offers high expansion ratios, thereby facilitating durable wound cover in the presence of limited donor sites. It is unlikely that a lethal dose, 50% (LD₅₀) of almost 70% TBSA would have been possible in this context without the regular application of this technique. This study advocates for the widespread availability of Meek micrografting and deceased donor allograft skin in developing countries.

Skin and skin substitutes in burn management

Early burn excision has reduced the mortality from major burns. This practice presents the problem of wound coverage after excision, since the availability of autologous donor sites is limited in very large burns. This article reviews the methods available for covering burn wounds. Methods of expanding autologous skin are discussed as well as techniques using allogeneic tissue and xenograft. Newer synthetic skin substitutes have become an important advance and are also described. Cultured skin replacements are also discussed along with their shortfalls. The treatment of a patient with major burns may require the use of many different skin substitutes, as none is entirely satisfactory on its own.

Retrospective review of a tertiary adult burn centre's experience with modified Meek grafting

Background

Autologous split skin grafting is the gold standard in treating patients with massive burns. However, the limited availability of donor sites remains a problem. The aim of this study is to present our experience with the modified Meek technique of grafting, outcomes achieved and recommendations for optimized outcomes.

Methods

We retrospectively reviewed patient records from our tertiary referral burn centre and the Bi-National Burns Registry to identify all patients who had modified Meek grafting between 2010 and 2013. Patient records were reviewed individually and information regarding patient demographics, mechanism of injury and surgical management was recorded. Outcome measures including graft take rate, requirement for further surgery and complications were also recorded.

Results

Eleven patients had modified Meek grafting procedures. The average age of patients was 46 years old (range 23 – 64). The average total body surface area (TBSA) burnt was 56.75 % (range 20–80 %). On average, 87 % of the grafted areas healed well and did not require regrafting. In the regrafted areas, infection was the leading cause of graft failure.

Conclusions

Modified Meek grafting is a useful method of skin expansion. Similar to any other grafting technique, infection needs to be sought and treated promptly. It is recommended for larger burns where donor sites are not adequate or where it is desirable to limit their extent.

Skin tissue engineering advances in severe burns: review and therapeutic applications

Current advances in basic stem cell research and tissue engineering augur well for the development of improved cultured skin tissue substitutes: a class of products that is still fraught with limitations for clinical use. Although the ability to grow autologous keratinocytes in-vitro from a small skin biopsy into sheets of stratified epithelium (within 3 to 4 weeks) helped alleviate the problem of insufficient donor site for extensive burn, many burn units still have to grapple with insufficient skin allografts which are used as intermediate wound coverage after burn excision. Alternatives offered by tissue-engineered skin dermal replacements to meet emergency demand have been used fairly successfully. Despite the availability of these commercial products, they all suffer from the same problems of extremely high cost, sub-normal skin microstructure and inconsistent engraftment, especially in full thickness burns. Clinical practice for severe burn treatment has since evolved to incorporate these tissue-engineered skin substitutes, usually as an adjunct to speed up epithelization for wound closure and/or to improve quality of life by improving the functional and cosmetic results long-term. This review seeks to bring the reader through the beginnings of skin tissue engineering, the utilization of some of the key products developed for the treatment of severe burns and the hope of harnessing stem cells to improve on current practice.

Lack of cross-sensitization between α-1,3-galactosyltransferase knockout porcine and allogeneic skin grafts permits serial grafting

BACKGROUND

The current standard of care for burns requiring operative treatment consists of early burn excision and autologous split-thickness skin grafting. However, in large burns, sufficient donor sites may not be available to achieve total coverage, necessitating temporary coverage with allogeneic human cadaver skin grafts or synthetic skin substitutes. A previous study from this laboratory demonstrated that skin grafts from alpha-1,3 galactosyltransferase knockout (GalT-KO) miniature swine enjoyed survival comparable to that of allogeneic skin grafts in baboons.

METHODS

In the present study, we have evaluated the immune response against sequential GalT-KO and allogeneic skin grafts to determine whether such serial grafts could extend the period of temporary wound coverage before definitive grafting with autologous skin.

RESULTS

We report that rejection of primary GalT-KO skin grafts led to an anti-xenogeneic humoral response with no evidence for sensitization to alloantigens nor acceleration of rejection of allogeneic skin grafts. Similarly, presensitization with allogeneic skin did not lead to accelerated rejection of xenogeneic skin.

CONCLUSIONS

These data suggest that GalT-KO skin grafts could provide an early first-line treatment in the management of severe burns that would not preclude subsequent use of allografts, and that serial grafting of GalT-KO skin and allogeneic skin could potentially be used to provide an extended period of temporary burn wound coverage.

Sandwich-type fiber scaffolds with square arrayed microwells and nanostructured cues as microskin grafts for skin regeneration

The paper reports the fabrication of sandwich-type scaffolds consisting of radially-aligned nanofibers at the bottom, nanofiber membranes with square arrayed microwells and nanostructured cues at the top, and microskin tissues in between as microskin grafts for use in skin regeneration. This class of nanofiber scaffolds was able to confine the microskin tissues in the square arrayed wells and simultaneously present nanotopographic cues to the cultured NIH 3T3 fibroblasts and primary rat skin cells, guiding and facilitating their migration in vitro. More importantly, we demonstrated that the sandwich-type transplants exhibited an even distribution of microskin grafts, greatly improved the 'take' rate of microskin tissues, and promoted re-epithelialization on wound in vivo. In addition, the void area in the scaffolds was well suitable for exudate drainage in wound. The sandwich-type scaffolds show great potential as microskin grafts for repairing extensive burn injuries and may provide a good solution for the treatment of acute skin defects and chronic wounds including diabetic ulcer, pressure ulcer, and venous stasis ulcer.

The use of the Meek technique in conjunction with cultured epithelial autograft in the management of major paediatric burns

BACKGROUND

The management of major paediatric burns remains challenging, in part due to limited donor sites. Skin graft expansion facilitates rapid closure of the burn wound, reducing the risk of sepsis. We reviewed our unit's experience with a combined modified Meek technique and cultured epithelial autograft (CEA).

METHODS

A retrospective chart review over a seven year period from April 2004 to April 2011 was conducted of patients whose burns were treated with Meek and CEA.

RESULTS

The Meek technique was combined with meshed split skin grafts and CEA to either donor, graft site or both in 7 cases. One case had Meek skin grafts alone with cultured cells applied to both donor and graft sites. There were two scald burns and five flame burns, with total body surface area ranging from 30% to 70%. Mean length of stay was 51 days (range 41-74 days). The average number of surgical procedures undergone to obtain good coverage was 3.3. There were small (1-3%) areas of breakdown in six cases which received regrafting. Two of these patients had confirmed wound infections. All patients had varying degrees of hypertrophic scarring (HTS) but remained well at follow up.

CONCLUSIONS

The Meek technique facilitates high expansion ratios, allowing for a greater area of skin coverage. Epithelialisation in the burn wound appeared to be enhanced by the application of CEA. The Meek technique in combination with CEA would appear a useful additional option in achieving wound closure in the severely burned paediatric patient.

Skin-specifically transgenic expression of biologically active human cytoxic T-lymphocyte associated antigen4-immunoglobulin (hCTLA4Ig) in mice using lentiviral vector

Xenogeneic skin, especially porcine skin, has already been used to cover large wounds in clinic practice of wound care. Our previous data showed that transgenic expression of human cytoxic T-lymphocyte associated antigen4-immunoglobulin (hCTLA4Ig) in murine skin graft remarkably prolonged its survival in xenogeneic burn wounds without extensive immunosuppression in recipients, suggesting that transgenic hCTLA4Ig expression in skin graft may be an effective and safe method to prolong its survival in xenogeneic wounds for coverage. Lentiviral transgenesis provides an extremely efficient and cost-effective method to produce transgenic animals. However, tissue-targeted transgenic expression of biologically functional protein by lentiviral transgenesis is rarely reported. In this work, a recombinant lentiviral vector (LV), named FKCW in this article, was constructed by inserting a skin-specific hCTLA4Ig expression cassette consisting of keratin 14 (K14) promoter, hCTLA4Ig coding sequence and an intronic fragment. Its efficacy for transgenesis and skin-specific expression of bio-active hCTLA4Ig protein was tested using mice as models. The LV FKCW was readily to be packaged and concentrated to high titres (1.287-6.254 × 10(9) TU/ml) by conventional lentivirus package system. Using eggs collected from only five mated females having been subjected to conventional super-ovulation treatment, 8 hCTLA4Ig transgenic founder mice were generated with the concentrated FKCW vector, and transgenic founder per injected and transferred egg was 6.3%, which was nearly 9-fold higher than that for DNA micro-injection with a similar transgene construct in our previous work. The lentiviral transgenic hCTLA4Ig exhibited strictly skin-specific expression at a level comparable to or even slightly higher than that of transgenic hCTLA4Ig delivered by micro-injection in a similar cassette. Lentiviral transgenic hCTLA4Ig protein remarkably suppressed human lymphocyte proliferation in vitro to a degree comparable to that of commercially purchased purified hCTLA4Ig protein with defined activity at similar concentrations. Besides, lentiviral hCTLA4Ig transgenic mouse skin grafted into rat burn wounds exhibited remarkably extended survival compared to wild-type skin of the same strain (13.8 ± 3.8 vs. 6.8 ± 3.0 days), indicating that lentiviral transgenic hCTLA4Ig did inhibit immune rejection against xenogeneic skin graft in vivo. These results laid down the foundation to further efficiently generate transgenic pigs skin-specifically expressing bio-active hCTLA4Ig by lentiviral transgenesis, and provided a demonstration that transgenic animals with tissue-targeted expression of biologically functional protein can be efficiently produced using LV.

Prolonged survival of GalT-KO swine skin on baboons

BACKGROUND

Allogeneic skin is currently the best alternative to autologous skin as a temporary treatment for severe burns, but it has several drawbacks. As a potential alternative, we have evaluated GalT-KO swine skin, which lacks expression of the Gal epitope, to investigate the effect of eliminating this epitope on survival of pig-to-baboon skin grafts.

METHODS

Two adult baboons that had fully recovered from previous T cell depletion received simultaneous skin grafts from: (i) GalT-KO swine, (ii) Gal-positive swine, (iii) a third-party baboon, and (iv) self (control skin). Recipients were treated with cyclosporin for 12 days and the survival, gross appearance, and histology of the grafts were compared.

RESULTS

In both baboons, the GalT-KO skin survived longer than either the Gal-positive swine skin or the allogeneic skin. Early rejection of the Gal-positive skin appeared to be mediated by cytotoxic preformed anti-Gal IgM antibodies, while the rejection of GalT-KO skin appeared to result from cellular mechanisms.

CONCLUSIONS

GalT-KO skin may have potential clinical benefits as an alternative to allogeneic skin as a temporary treatment for severe skin injuries.

The micrograft concept for wound healing: strategies and applications

The standard of care for wound coverage is to use an autologous skin graft. However, large or chronic wounds become an exceptionally challenging problem especially when donor sites are limited. It is important that the clinician be aware of various treatment modalities for wound care and incorporate those methods appropriately in the proper clinical context. This report reviews an alternative to traditional meshed skin grafting for wound coverage: micrografting. The physiological concept of micrografting, along with historical context, and the evolution of the technique are discussed, as well as studies needed for micrograft characterization and future applications of the technique.

Adult burn patients with more than 60% TBSA involved-Meek and other techniques to overcome restricted skin harvest availability--the Viennese Concept

Despite the fact that early excision and grafting has significantly improved outcome over the last decades, the management of severely burned adult patients with >/=60% total body surface area (% TBSA) burned still represents a challenging task for burn care specialists all over the world. In this article, we present our current treatment concept for this entity of severely burned patients and analyze its effect in a comparative cohort study. Surgical strategy comprised the use of split-thickness skin grafts (Meek, mesh) for permanent coverage, fluidized microsphere bead-beds for wound conditioning, temporary coverage (polyurethane sheets, Epigard; nanocrystalline silver dressings, Acticoat; synthetic copolymer sheets based on lactic acid, Suprathel; acellular bovine derived collagen matrices, Matriderm; allogeneic cultured keratinocyte sheets; and allogeneic split-thickness skin grafts), and negative-pressure wound therapy (vacuum-assisted closure). The autologous split-thickness skin graft expansion using the Meek technique for full-thickness burns and the delayed approach for treating dorsal burn wounds is discussed in detail. To demonstrate differences before and after the introduction of the Meek technique, we have compared patients of 2007 with >/=60% TBSA (n = 10) to those in a matched observation period (n = 7). In the first part of the comparative analysis, all patients of the two samples were analyzed with regard to age, abbreviated burn severity index, Baux, different entities of % TBSA, and survival. In the second step, only the survivors of both years were separated in two groups as follows: patients receiving skin grafts, using the Meek technique (n = 6), were compared with those without Meek grafting (n = 4). When comparing the severely burned patients of 2007 with a cohort of 2006, there were no differences for age (2007: 46.4 +/- 13.4 vs. 2006: 39.1 +/- 14.8 years), abbreviated burn severity index score (2007: 12.2 +/- 1.0 vs. 2006: 12.1 +/- 1.2) or % TBSA (2007: 72.1 +/- 11.7 vs. 2006: 69.3 +/- 8.7% TBSA). In these two rather small groups of severely burned patients with >/=60% TBSA, the overall survival rate of patients was 70.0% (7/10) in 2007 and 42.9% (3/7) in 2006, respectively. Almost all nonsurvivors in both years died within the first 5 days after admission. If assessing the different treatment modalities of the survivors, we found that although the Meek group patients were older (Meek 48.8 +/- 13.3 vs. non-Meek 26.8 +/- 11.5 years, P = .0381) and had consequently higher Baux scores (Meek 124.0 +/- 2.9 vs. non-Meek 93.8 +/- 8.5, P = .0095) than the non-Meek patients, this seemed to have no effect on length-of-stay (80.5 +/- 9.7 vs. non-Meek 79.8 +/- 33.0 days), hospital length-of-stay (85.7 +/- 14.8 vs. non-meek 84.3 +/- 26.1 days) or number of operations (6.5 +/- 1.0 vs. non-Meek 7.0 +/- 4.1 operations). The achieved results represent a combination of various treatment changes and, therefore, cannot be attributed to a single modality. The Meek technique is one of the technical options to choose from, to achieve permanent skin replacement; we think that it has its place if integrated in a whole treatment concept for management of severely burned patients.

Economics of pediatric burns

Sustaining a burn injury sets in motion a cycle of pain, disfigurement, and a search for survival. In pediatric burns, the injury extends to the parents where fear, ignorance, and helplessness forever change their lives. Pediatric burn injuries are caused by fire, hot liquids, clothing irons, hair curlers, caustic substances like drain cleaner, the grounding of an electrical source, and exposure to radiation. Efficiency in the delivery of pediatric burn care is critical. Maximizing resource utilization means continual self-evaluation and economic analysis of therapeutic modalities. Griffiths et al found that most childhood burns are due to scalds, which can be treated for $1061 per percent burn. Paddock et al reduced the cost of treating superficial pediatric burns and reduced the length of stay in hospital using silver-impregnated gauze over traditional methods. Barrett et al found improved cosmesis of skin grafts using cultured epithelial autografts but at a substantially increased cost. Corpron et al showed that pediatric burn units that treat burns >10% total body surface area and operative treatment of pediatric burns regardless of size generate positive revenue. There is a paucity of evidentiary pediatric burn economic data. More research is needed to address areas of pediatric burn care inefficiency. Improving knowledge of cost in all health care endeavors will create competition and drive down expenditures.

Five years' experience of the modified Meek technique in the management of extensive burns

BACKGROUND

The Meek technique of skin expansion is useful for covering a large open wound with a small piece of skin graft, but requires a carefully followed protocol.

METHODS

Over the past 5 years, a skin graft expansion technique following the Meek principle was used to treat 37 individuals who had sustained third degree burns involving more than 40% of the body surface. A scheme was devised whereby the body was divided into six areas, in order to clarify the optimal order of wound debridements and skin grafting procedures as well as the regimen of aftercare.

RESULTS

The mean body surface involvement was 72.9% and the mean area of third degree burns was 41%. The average number of operations required was 1.84. There were four deaths among in this group of patients.

CONCLUSIONS

The Meek technique of skin expansion and the suggested protocol are together efficient and effective in covering an open wound, particularly where there is a paucity of skin graft donor sites.

A general overview of burn care

The majority of burn victims do not need to be treated in a burn centre. Adequate care can be given by non specialised medical personnel, provided that proper guidelines are followed. The article outlines and reviews these guidelines.

“Flypaper technique” a modified expansion method for preparation of postage stamp autografts

The gold standard for management of extensive burn has been early excision, temporary allografting and final autografting. However, "lack of donor skin" is a challenge condition when autografting in the treatment of extensive burns. Designing an efficient and easy to apply expansion method may improve burn care quality and shorten the hospital stay period. From December 1998 to May 2004, we have performed fly paper technique postage stamp skin autografting for eight major burn patients in the Kaohsiung Medical University Hospital. By using a quick cutting plate, chessboard tray and petrolatum gauze, the skin islands can be uniformly located and correctly oriented on gauze. Then, the gauze with skin islands was grafted on to the wound. The wound healing time depends on the size of skin islands and expansion ratio. This method allows true expansion ratio up to nine times. The average wound healing times are 27.2 days for six times expansion and 34 days for nine times expansion. However, the burn scar needs further compression therapy to improve the cosmetic result. In comparison with the mesh technique, the skin islands are independent of each other, any dislodgement of a skin island will not interfere with the surrounding skin squares. When compared with the modified Meek technique, this method also offers rapid wound reepithilization but with lower cost. This flypaper technique is worthy of consideration in dealing with the extensive burns.