Clinical trials of amniotic membranes in burn wound care

Skin substitutes for the management of mohs micrographic surgery wounds: a systematic review

The data on skin substitute usage for managing Mohs micrographic surgery (MMS) wounds remain limited. This systematic review aimed to provide an overview of skin substitutes employed for MMS reconstruction, summarize clinical characteristics of patients undergoing skin substitute-based repair after MMS, and identify advantages and limitations of skin substitute implementation. A systematic review of Ovid MEDLINE, EMBASE, Cochrane Library, and Web of Science databases, from inception to April 7, 2021, identified all cases of MMS defects repaired using skin substitutes. A total of 687 patients were included. The mean patient age was 70 years (range: 6-98 years). Commonly used skin substitutes were porcine collagen (n = 397), bovine collagen (n = 78), Integra (n = 53), Hyalofill (n = 43), amnion/chorion-derived grafts (n = 40), and allogeneic epidermal-dermal composite grafts (n = 35). Common factors influencing skin substitute selection were cost, healing efficacy, cosmetic outcome, patient comfort, and ease of use. Some articles did not specify patient and wound characteristics. Skin substitute usage in MMS reconstruction is not well-guided. Blinded randomized control trials comparing the efficacy of skin substitutes and traditional repair methods are imperative for establishing evidence-based guidelines on skin substitute usage following MMS.

Standardized reporting of amnion and amnion/chorion allograft data for wound care

Background

The favorable biological and mechanical properties of the most common components of the placenta, the amnion and chorion, have been explored for regenerative medical indications. The use of the combination of amnion and chorion has also become very popular. But, published data from placental tissues in their final, useable form is lacking. During treatment with membrane product, the tissue is usually sterile, intact and laid on a wound or treatment area. The factors available to the treatment area from the applied product need to be elucidated and presented in a relatable form. Current reporting for eluted growth factor results are typically expressed per milliliter, which is not informative with respect to the area of tissue covered by the actual membrane and may differ among techniques.

Methods

To address this inconsistency, amnion or amnion/chorion were isolated from human placentas and processed by a proprietary procedure. The final dry, sterilized product was evaluated for structural components and growth factor elution. Growth factors were quantified by multiplex panels and ELISAs and the values normalized to specific area and elution volume of finished product. This information allows extrapolation to all membrane sizes and affords cross‐study comparisons.

Results

Analysis of membrane supernatants show that dehydrated, sterilized amnion and amnion/chorion elute factors that are conducive to wound healing, which are available to recipient tissues. Importantly, these measurable factors eluted from dehydrated, sterilized membranes can be reported as a function of available factors per square centimeter of tissue.

Conclusions

The standardized characterization of dehydrated, sterilized amnion and amnion/chorion as delivered to recipient tissues permits understanding and comparison of the products across various graft sizes, types, and eluate volumes. Further, reporting this data as a function of cm² of dehydrated tissue allows extrapolation by independent scientists and clinicians.

Using Dry Human Amniotic Membrane in Secondary Intention Wound Healing After Urological Cancer Surgery: The First Randomized Clinical Trial in Iran

Background: Wound healing is a complex process and in some patients, it is a long process. Due to the presence of various underlying diseases in patients with cancer, this process is delayed, and as a result, the rate of complications increases. Therefore, some materials are needed to accelerate wound healing. Nowadays efficacy of dry human amniotic membrane in burn wounds and chronic wounds is proven; however, no studies have been performed on the effect of this tissue in the treatment of surgical wounds. Objectives: This study aimed at evaluating the efficacy of dry human amniotic membrane in the secondary repair of urological cancer surgery wounds. Methods: In this randomized clinical trial from January 2018 to June 2020, 40 patients who underwent urological cancer surgery and secondary intention wound healing were selected and randomly divided into 2 groups of 20 patients. In the case group, the dry human amniotic membrane was used for dressing wounds, and in the control group, normal dressing without an amniotic membrane was performed. Complications such as infection, sepsis, and reoperation, as well as the duration of wound healing and hospitalization of patients at intervals of 1 week, 1, and 3 months, were compared between the 2 groups. Results: The 2 groups matched in terms of gender, age, and wound location. The mean duration of hospitalization and wound healing was significantly lower in the case group (P < 0.05). The rate of complications was higher in the control group but was not significant. Conclusions: Dry human amniotic membranes due to the accelerated wound healing process and fewer complications could be a good choice for secondary healing of wounds after urological cancer surgery.

Current and Emerging Topical Scar Mitigation Therapies for Craniofacial Burn Wound Healing

Burn injury in the craniofacial region causes significant health and psychosocial consequences and presents unique reconstructive challenges. Healing of severely burned skin and underlying soft tissue is a dynamic process involving many pathophysiological factors, often leading to devastating outcomes such as the formation of hypertrophic scars and debilitating contractures. There are limited treatment options currently used for post-burn scar mitigation but recent advances in our knowledge of the cellular and molecular wound and scar pathophysiology have allowed for development of new treatment concepts. Clinical effectiveness of these experimental therapies is currently being evaluated. In this review, we discuss current topical therapies for craniofacial burn injuries and emerging new therapeutic concepts that are highly translational.

Skin substitutes for acute and chronic wound healing: an updated review

Background: Skin substitutes are designed to accelerate wound healing by providing replacement of extracellular matrix and can be used to promote healing of both acute and chronic wounds.Aim: To describe advantages, disadvantages, and indications for different skin substitutes with the intention of providing a systematic framework that clinicians can easily utilize in clinical practice.Materials and method: We conducted a PubMed, Cochrane Library, and company website search for publications using various search terms associated with skin substitutes.Results: Skin substitutes can be categorized as epidermal, dermal, and composite, depending on the skin component they contain, and further split into different categories depending on their composition and source of material, including xenograft, acellular allograft, cellular allograft, autograft, and synthetic skin substitutes. Because there is no ideal option for skin substitutes that meet all the criteria for optimal wound healing, there is ongoing research evaluating and developing different skin substitute options.Conclusion: Our model of skin substitutes was organized based on the different layers of cutaneous involvement and the origin of the product material. We believe that this framework provides a practical guide for selection of the most appropriate skin substitute based on clinical indication.

Wound Coverage Technologies in Burn Care: Established Techniques

Major advances in burn care have reduced post-burn morbidity and mortality. The development and incorporation of new wound healing modalities into the clinical arena have contributed to this improvement by allowing standard-of-care regimens to be established. These regimens range from early excision to the use of cultured epithelial autograft. Here, we review the wound care options that are now well established and used by many burn surgeons.

Benefits of cryopreserved human amniotic membranes in association with conventional treatments in the management of full-thickness burns

The use of split-thickness skin autografts (STSA) with dermal substitutes is the gold standard treatment for third-degree burn patients. In this article, we tested whether cryopreserved amniotic membranes could be beneficial to the current treatments for full-thickness burns. Swines were subjected to standardised full-thickness burn injuries, and then were randomly assigned to treatments: (a) STSA alone; (b) STSA associated with the dermal substitute, Matriderm; (c) STSA plus human amniotic membrane (HAM); and (d) STSA associated with Matriderm plus HAM. Clinical and histological assessments were performed over time. We also reported the clinical use of HAM in one patient. The addition of HAM to classic treatments reduced scar contraction. In the presence of HAM, skin wound healing displayed high elasticity and histological examination showed a dense network of long elastic fibres. The presence of HAM increased dermal neovascularization, but no effect was observed on the recruitment of inflammatory cells to the wound. Moreover, the use of HAM with classical treatments in one human patient revealed a clear benefit in terms of elasticity. These results give initial evidence to consider the clinical application of HAM to avoid post-burn contractures and therefore facilitate functional recovery after deep burn injury.

Amnion membrane hydrogel and amnion membrane powder accelerate wound healing in a full thickness porcine skin wound model

There is a need for effective wound treatments that retain the bioactivity of a cellular treatment, but without the high costs and complexities associated with manufacturing, storing, and applying living biological products. Previously, we developed an amnion membrane‐derived hydrogel and evaluated its wound healing properties using a mouse wound model. In this study, we used a full thickness porcine skin wound model to evaluate the wound‐healing efficacy of the amnion hydrogel and a less‐processed amnion product comprising a lyophilized amnion membrane powder. These products were compared with commercially available amnion and nonamnion wound healing products. We found that the amnion hydrogel and amnion powder treatments demonstrated significant and rapid wound healing, driven primarily by new epithelialization versus closure by contraction. Histological analysis demonstrated that these treatments promote the formation of a mature epidermis and dermis with similar composition to healthy skin. The positive skin regenerative outcomes using amnion hydrogel and amnion powder treatments in a large animal model further demonstrate their potential translational value for human wound treatments.

A multicentre randomised controlled trial evaluating the efficacy of dehydrated human amnion/chorion membrane (EpiFix® ) allograft for the treatment of venous leg ulcers

A randomised, controlled, multicentre clinical trial was conducted to evaluate the efficacy of dehydrated human amnion/chorion membrane (EpiFix) allograft as an adjunct to multilayer compression therapy for the treatment of non-healing full-thickness venous leg ulcers. We randomly assigned 109 subjects to receive EpiFix and multilayer compression (n = 52) or dressings and multilayer compression therapy alone (n = 57). Patients were recruited from 15 centres around the USA and were followed up for 16 weeks. The primary end point of the study was defined as time to complete ulcer healing. Participants receiving weekly application of EpiFix and compression were significantly more likely to experience complete wound healing than those receiving standard wound care and compression (60% versus 35% at 12 weeks, P = 0·0128, and 71% versus 44% at 16 weeks, P = 0·0065). A Kaplan-Meier analysis was performed to compare the time-to-healing performance with or without EpiFix, showing a significantly improved time to healing using the allograft (log-rank P = 0·0110). Cox regression analysis showed that subjects treated with EpiFix had a significantly higher probability of complete healing within 12 weeks (HR: 2·26, 95% confidence interval 1·25-4·10, P = 0·01) versus without EpiFix. These results confirm the advantage of EpiFix allograft as an adjunct to multilayer compression therapy for the treatment of non-healing, full-thickness venous leg ulcers.

Solubilized Amnion Membrane Hyaluronic Acid Hydrogel Accelerates Full-Thickness Wound Healing

The early and effective treatment of wounds is vital to ensure proper wound closure and healing with appropriate functional and cosmetic outcomes. The use of human amnion membranes for wound care has been shown to be safe and effective. However, the difficulty in handling and placing thin sheets of membrane, and the high costs associated with the use of living cellularized tissue has limited the clinical application of amniotic membrane wound healing products. Here, we describe a novel amnion membrane-derived product, processed to result in a cell-free solution, while maintaining high concentrations of cell-derived cytokines and growth factors. The solubilized amnion membrane (SAM) combined with the carrier hyaluronic acid (HA) hydrogel (HA-SAM) is easy to produce, store, and apply to wounds. We demonstrated the efficacy of HA-SAM as a wound treatment using a full-thickness murine wound model. HA-SAM significantly accelerated wound closure through re-epithelialization and prevented wound contraction. HA-SAM-treated wounds had thicker regenerated skin, increased total number of blood vessels, and greater numbers of proliferating keratinocytes within the epidermis. Overall, this study confirms the efficacy of the amnion membrane as a wound treatment/dressing, and overcomes many of the limitations associated with using fresh, cryopreserved, or dehydrated tissue by providing a hydrogel delivery system for SAM. Stem Cells Translational Medicine 2017;6:2020-2032.

Contemporary Methods Allowing for Safe and Convenient Use of Amniotic Membrane as a Biologic Wound Dressing for Burns

Partial-thickness burns involve damage to the upper layer of skin, which leaves nerve endings exposed, and therefore represent the most painful of several categories of thermal injuries. Historically, partial-thickness burns were treated conservatively by debriding the blisters, by daily tubbing and washing, and the application of new bandages with topical medications. Human amniotic membrane has been used for centuries as a biological wound dressing. In the past 20 years, there has been an increasing body of literature addressing the use of amniotic tissue in chronic wounds and burns. In this review, we present an overview of the use of amniotic membrane in the treatment of burns including processing methods and early clinical use. We believe that amniotic membranes have great potential in improving burn wound care in the future. Standardized processing methods and terminal sterilization ensure safety and allow the material to be available for use by health care providers around the world in clinical trials and for patient care.

Hypertrophic scarring: the greatest unmet challenge after burn injury

Improvements in acute burn care have enabled patients to survive massive burns that would have once been fatal. Now up to 70% of patients develop hypertrophic scars after burns. The functional and psychosocial sequelae remain a major rehabilitative challenge, decreasing quality of life and delaying reintegration into society. Approaches to optimise healing potential of burn wounds use targeted wound care and surgery to minimise the development of hypertrophic scarring. Such approaches often fail, and modulation of the established scar is continued although the optimal indication, timing, and combination of therapies have yet to be established. The need for novel treatments is paramount, and future efforts to improve outcomes and quality of life should include optimisation of wound healing to attenuate or prevent hypertrophic scarring, well-designed trials to confirm treatment efficacy, and further elucidation of molecular mechanisms to allow development of new preventive and therapeutic strategies.

Reinforcement of the Flexor Tendon Repair Using Human Amniotic MembraneA Biomechanical Evaluation Using the Modified Kessler Method of Tendon Repair

BACKGROUND

Human amniotic membrane is used to prevent peritendinous adhesions after tendon injuries. This study compares the mechanical properties of modified Kessler repairs and modified Kessler repairs strengthened using multiple layers of human amniotic membrane.

METHODS

Twenty flexor digitorum profundus tendons of sheep forelimbs were sutured by the two-strand modified Kessler technique (group A) and by the two-strand modified Kessler repair reinforced with multiple layers of human amniotic membrane (group B). To assess the mechanical performance of the repairs, tendons were subjected to a linear noncyclic load-to-failure test using a material testing machine. Outcome measures included ultimate forces and the mode of failure.

RESULTS

The mean ± SD value of the failure strength was 34.6 ± 1.64 N for group A and 50.6 ± 5.60 N for group B. The reinforced repair provided a significantly higher ultimate load compared with the nonreinforced group (P < .001). All of the specimens failed due to suture breakage at the repair site.

CONCLUSIONS

The results of this study show that the modified Kessler repair can be reinforced effectively with human amniotic membrane.

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.

Use of Amnion Transfer in Resistant Nonhealing Venous Leg Ulcers

In the treatment of venous leg ulcers, after adopting many treatment modalities, at times we are still left with a local indolent problem, "the resistant nonhealing venous ulcer." With repeated surgical procedures failing to obtain a healed ulcer, constant pain, persistent discharging wound, infections, etc., many a patient turn hostile. Also, there comes a dimension of despair in the health feeling of the patient. This prospective study was conducted in 40 patients, who were within the inclusion criteria (January 2006-January 2010, 12 males and 28 females, mean age 45 years). A single amniotic membrane (AM) transfer was done after preparation of the wound, and the parameters were assessed periodically. Follow-up for a minimum period of 1 year in all cases and a maximum period of 3 years in many cases (38) was done. Significant clinical response was defined as an ulcer healing greater than 75 % of the original area. Treatment failure was taken as a persistence or recurrence of more than 25 % of the ulcer area in a 1-year follow-up period. The preliminary results of good ulcer healing and no recurrence are encouraging, even up to 3-year follow-up. This proof-of-concept study demonstrates that AM transfer is useful, safe, inexpensive, readily available, and well accepted by patients, with tremendous potential in promoting epithelial healing in "the resistant nonhealing chronic venous leg ulcer."

Clinical effect of bovine amniotic membrane and hydrocolloid on wound by laser treatment: prospective comparative randomized clinical trial

Bovine amniotic membrane (BAM) has been regarded as an ideal dressing material because it accelerates epithelization and has anti-inflammatory, anti-angiogenic, and strong analgesic effects. To evaluate the clinical effects of BAM and compare them to that of hydrocolloid dressings on wounds created by ablative laser treatments, 49 subjects with nevi or scars requiring ablative laser treatment were evaluated. To compare efficacy, we divided the body into six areas and included patients with two or more similar skin lesions in the same body area. After ablative laser treatments, BAM and hydrocolloid dressing were applied to the wounds with random allocation. Clinical assessments were performed at baseline, 1, 4, 6, 8, 11, and 13 days after treatment. Histologic changes were assessed by skin biopsy. BAM treatment induced faster epithelization than hydrocolloid treatment (6.7 vs. 9.2 days). Erythema and oozing faded more quickly, and the satisfaction score was higher in BAM-treated sites than it was in hydrocolloid-treated sites, without severe adverse effects. Histologic analysis confirmed epithelization and immunohistochemistry revealed different growth factor profiles between the two treatment modalities. BAM benefits wound healing following ablative laser treatment.

Advancement of wound care from grafts to bioengineered smart skin substitutes

This review gives a brief description on the skin and its essential functions, damages or injury which are common to the skin and the role of skin substitute to replace the functions of the skin soon after an injury. Skin substitutes have crucial role in the management of deep dermal and full thickness wounds. At present, there is no skin substitute in the market that can replace all the functions of skin 'and the research is still continuing for a better alternative. This review is an attempt to recollect and report the past efforts including skin grafting and recent trends like use of bioengineered smart skin substitutes in wound care. Incorporation functional moieties like antimicrobials and wound healing agents are also described.

Acellular amniotic membrane: an appropriate scaffold for fibroblast proliferation

BACKGROUND

Various materials have been investigated as possible skin substitutes to repair skin defects such as burns. Because of its unique characteristics, acellular amniotic membrane seems to provide a good scaffold for cell cultures.

AIM

To investigate the proliferation of fibroblasts on an amniotic membrane scaffold, and the preparation of a temporary skin substitute using this method.

METHODS

Neonatal foreskin tissue was harvested after circumcision and used for isolation of skin fibroblasts. The skin sample was refrigerated in cell-culture solution, and later treated with trypsin, minced, and incubated in the same solution at 37 °C with in an atmosphere of 95% O2 /5% CO2 . The confluent cultures were treated with trypsin, and fibroblasts were subcultured up to the 10th passage. Cells were tested for microbial contamination, presentation of major histocompatibility complex, and karyotype changes. Amniotic membrane was harvested after elective caesarean section from donors who had been screened for infection. The membrane was washed and then subjected to three freeze-thaw cycles, before having the cells removed. The fibroblasts were seeded onto the scaffold, and after 24 h, the prepared skin substitute was ready. This was examined under electron microscopy.

RESULTS

The skin substitute showed excellent growth of fibroblasts on the amniotic membrane scaffold.

CONCLUSIONS

Fibroblasts had excellent adherence to and viability on the acellular amniotic membrane, which seems to provide an acceptable temporary skin substitute that can be used for wounds.

Augmented dried versus cryopreserved amniotic membrane as an ocular surface dressing

Purpose

Dried amniotic membrane (AM) can be a useful therapeutic adjunct in ophthalmic surgery and possesses logistical advantages over cryopreserved AM. Differences in preservation techniques can significantly influence the biochemical composition and physical properties of AM, potentially affecting clinical efficacy. This study was established to investigate the biochemical and structural effects of drying AM in the absence and presence of saccharide lyoprotectants and its biocompatibility compared to cryopreserved material.

Methods

AM was cryopreserved or dried with and without pre-treatment with trehalose or raffinose and the antioxidant epigallocatechin (EGCG). Structural and visual comparisons were assessed using electron microscopy. Localisation, expression and release of AM biological factors were determined using immunoassays and immunofluorescence. The biocompatibility of the AM preparations co-cultured with corneal epithelial cell (CEC) or keratocyte monolayers were assessed using cell proliferation, cytotoxicity, apoptosis and migration assays.

Results

Drying devitalised AM epithelium, but less than cryopreservation and cellular damage was reduced in dried AM pre-treated with trehalose or raffinose. Dried AM alone, and with trehalose or raffinose showed greater factor retention efficiencies and bioavailability compared to cryopreserved AM and demonstrated a more sustained biochemical factor time release in vitro. Cellular health assays showed that dried AM with trehalose or raffinose are compatible and superior substrates compared to cryopreserved AM for primary CEC expansion, with increased proliferation and reduced LDH and caspase-3 levels. This concept was supported by improved wound healing in an immortalised human CEC line (hiCEC) co-cultured with dried and trehalose or raffinose membranes, compared to cryopreserved and fresh AM.

Conclusions

Our modified preservation process and our resultant optimised dried AM has enhanced structural properties and biochemical stability and is a superior substrate to conventional cryopreserved AM. In addition this product is stable and easily transportable allowing it to be globally wide reaching for use in clinical and military sectors.

Secondary correction of posttraumatic orbital wall adhesions by membranes laminated with amniotic membrane

The objective of the study was to find out if human amniotic membrane could be used for corrective surgery after trauma to the orbital wall. Because of its proposed antiadhesive qualities, it seemed to be potentially suitable. We studied 8 men (mean age 37 (range 19-74) years) who had deficient ocular movement after fractures of the orbital floor. Five of them had already been operated on. Inclusion criteria were trauma dating back more than 4 months and a soft tissue stricture in the orbital floor diagnosed by magnetic resonance imaging. Patients were treated secondarily with lysis of adhesions and insertion of allogeneic human amniotic membrane laminated on to polyglactin 910/polydioxanone foil, which functioned as the carrier material. Patients were followed up for 3 months, by which time disorders of motility of the ocular bulb had disappeared completely in 5. Two patients had improved motility and a reduction in both their subjective and objective symptoms. One patient had no improvement. The considerable reduction in adhesions and scarring after insertion of the membrane confirms previous assumptions, according to which the epithelial side of the human amniotic membrane has an antiadhesive effect because of its smooth surface.

Amniotic membrane grafting in patients with epidermolysis bullosa with chronic wounds

BACKGROUND

Severe forms of epidermolysis bullosa (EB) are characterized by chronic, nonhealing wounds.

OBJECTIVE

We sought to evaluate the usefulness of amniotic membranes in patients with EB.

METHODS

A retrospective chart review of patients with EB who were treated with amniotic membranes (two patients, 8 applications) was conducted. The primary outcome measure was number of days to complete healing, and the secondary outcome measures were a qualitative wound score, a visual analog scale score, and potential adverse effects.

RESULTS

The number of days to detect a significant clinical response, defined as greater than 50% improvement, was 40.3 +/- 21.2 days. The median qualitative wound score was 2 (range 0-5). The mean visual analog scale score at last follow-up was 31.4 +/- 26.8. No adverse events were noted.

LIMITATIONS

Retrospective design, healing assessed by comparing photographs, and partial grafting of some wounds were limitations.

CONCLUSION

This proof-of-concept study revealed the potential usefulness of amniotic membrane grafting in promoting healing of chronic wounds in patients with EB.

Principles of wound care in patients with epidermolysis bullosa

Epidermolysis bullosa comprises a series of hereditary skin fragility disorders characterized by blister formation in response to minor friction or trauma. Acute and chronic wounds are part of the daily life of many epidermolysis bullosa patients. To offer proper care, health care providers need to understand the wound healing process, recognize the different types of wounds these patients may present, and be able to select among a wide variety of wound care products to optimize healing.

Human amnion as a novel cell delivery vehicle for chondrogenic mesenchymal stem cells

This study investigates the feasibility of processed human amnion (HAM) as a substrate for chondrogenic differentiation of mesenchymal stem cells (MSCs). HAM preparations processed by air drying (AD) and freeze drying (FD) underwent histological examination and MSC seeding in chondrogenic medium for 15 days. Monolayer cultures were used as control for chondrogenic differentiation and HAMs without cell seeding were used as negative control. Qualitative observations were made using scanning electron microscopy analysis and quantitative analyses were based on the sulfated glycosaminoglycans (GAG) assays performed on day 1 and day 15. Histological examination of HAM substrates before seeding revealed a smooth surface in AD substrates, while the FD substrates exhibited a porous surface. Cell attachment to AD and FD substrates on day 15 was qualitatively comparable. GAG were significantly highly expressed in cells seeded on FD HAM substrates. This study indicates that processed HAM is a potentially valuable material as a cell-carrier for MSC differentiation.

The role of allogenic amniotic membrane in burn treatment

Amniotic membrane (AM) has been used in burns for nearly 100 years. The purpose of this article is to give a comprehensive review of the English literature published in the last two decades (1987--2007) to present the current state of this therapy form. Three medical databases (PubMed, Medline, The Cochrane Library) and specific burn journals were electronically screened for relevant articles using carefully selected retrieval strategies and keywords (AM, amnion grafts, burns, wound dressing, amnion banking). Bibliographies of relevant articles were analyzed for additional pertinent publications. After exclusion of articles which referred to the use of AM in reconstructive and ophthalmologic surgery, the inquiry yielded 31 relevant articles in English language dealing with AM and burns. There was no publication fulfilling the criteria of evidence level I, 6 articles had evidence level II, 10 had evidence level III, 6 had evidence level IV, and 9 were merely narrative (level V). The review testifies to--in view of good tissue practice--heightened use of processed AM in burns, especially in the last decade. Randomized clinical trials favored the use of amnion in burns in the first place for promotion of wound healing and in the second place for its comfortable and less dressing changes. Antimicrobial effects, pain relief, reduction of fluid, and scar formation were demonstrated additionally.

Reconstruction of rabbit corneal epithelium on lyophilized amniotic membrane using the tilting dynamic culture method

Rabbit corneal epithelium was reconstructed using tilting dynamic culture with a self-manufactured, amniotic membrane (AM) supporter and a lyophilized amniotic membrane (LAM). Rabbit corneal epithelial (RCE) cells were cultured and cryopreserved after isolation from the limbus. The second- and third-passage RCE cells were plated onto the epithelial side of the LAM of Ahn's AM supporter. Two days later, the air-liquid interface culture was maintained with third-passage RCE cells for 6 days and second-passage corneal epithelial cells for 9 days. The average viability of thawed RCE cells, assessed using trypan blue dye exclusion, was 77.42%. The reconstructed corneal epithelium was characterized by histological (hematoxylin and eosin) and immunohistochemical staining (proliferating cell nuclear antigen) for light microscopy, and by reverse transcriptase-polymerase chain reaction, glucose assay, and transmission electron microscopy. The basal layer of the reconstructed corneal epithelium was well formed, and the epithelium was tightly constructed due to the increase in cell proliferation and differentiation caused by the tilting dynamic culture, as opposed to static culture. Tilting dynamic culture was useful for the reconstruction of the epithelium using easily damaged epithelial cells and resulted in more stratum cell layers. Moreover, cytokeratin (CK3) mRNA expression in tilting dynamic cultured third-passage RCE cells seeded onto AM was greater than in static cultured third-passage RCE cells. The morphology of the reconstructed corneal epithelium on LAM by tilting dynamic culture for 9 days resembled that of the skin epidermis. This was thought to be because the tilting dynamic culture not only accelerated the proliferation and differentiation of cells by physical or mechanical stimulation, but also ensured that the supply of medium was delivered to the basal cells more efficiently. Thus, the reconstruction of the corneal epithelium using LAM and tilting dynamic culture was considered to be a good in vitro model for autologous or allogeneic transplantation of corneal epithelium and skin epidermis in patients with damaged epithelia.

Amnion in the treatment of pediatric partial-thickness facial burns

BACKGROUND

Wound coverage for second-degree burns remains a clinical challenge. Human amniotic membranes have been used for many years in the treatment of burns; however, no large prospective clinical trials have been published. In this article, we present a novel and standardized procurement and processing method for amnion and investigate, whether the use of this biological dressing is safe and may represent a new therapeutic option for children with partial-thickness facial burns compared to standard topical treatment.

METHODS

Patients with partial-thickness burns of the face, neck and head admitted between 2003 and 2005 were included in this study. They were divided into two groups to receive either amnion (n=53) or topical antimicrobials (n=49). Demographics (age, gender, ethnicity, TBSA, burn areas), length of hospital stay (LOS), rate of infections (RI), time to total healing, and frequency of dressing changes were compared between the two groups. The long-term outcome was assessed in nine patients in the amnion group and eight patients in the topical group, who returned for up to 12-month follow-up visits.

RESULTS

Patients in the amnion group had significantly less dressing changes then in the control group (p<0.05). Time to healing, length of stay and the development of hypertrophic scarring was not different between the groups. Use of amnion was not associated with an increased risk of local infection.

CONCLUSION

This study indicates that amnion is safe and has advantages as wound coverage for second-degree facial burns compared to the standard topical ointments. Further studies with the use of amniotic membranes on the trunk and the extremities, as well as for coverage of grafted third-degree burns, have yet to be performed.

[Cryopreserved amniotic membranes use in resistant vascular ulcers]

BACKGROUND AND OBJECTIVE

Amniotic membranes are used with success in ophthalmology to treat corneal wounds and ulcers. In this pilot study, we attempt to assess the tolerance of amniotic membranes in the management of resistant venous and/or arterial vascular ulcers.

MATERIAL AND METHODS

We prospectively included 8 patients, 7 males and 1 female, mean age 69.5+/- 9.6 years, with venous and/or arterial ulcers resistant after 6 months with usual medical care and/or after revascularisation failure. Amniotic membranes were applied on a weekly basis with the fetal side on the ulcer, covered by a secondary bandage. The primary end-point was evaluation of tolerance of amniotic membranes on vascular ulcers. The secondary end-points were a >50% reduction of ulcer's area, a significant (P< or =0.05) improvement of pain visual scale score and the quality of life assessed by the SF-36 questionnaire.

RESULTS

Tolerance was excellent in all cases. We observed no adverse effect. We observed complete healing at weeks 19 and 26 for 2 patients and a >50% reduction of ulcer area at weeks 26, 31 and 32 for 3 patients. A sixth patient had an ulcer area reduction <50% and the 2 remaining showed no improvement. A significant improvement was noticed for visual pain scale and the health feeling dimension in the SF-36 questionnaire. No adverse effect or amputation requirement was noted.

CONCLUSION

These preliminary results are encouraging and require a larger confirmatory study. Further studies are required to clarify the action mode of this therapeutic option.

Suprathel®—An innovative, resorbable skin substitute for the treatment of burn victims

Autologous split skin grafts are the most reliable method for closing third degree burns. Under this scheme, donor sites as well as second degree burns under conservative treatment, however, would benefit from rapid wound closure. For this treatment, biological as well as synthetic materials are available. For the improvement of these materials, primary goals are pain reduction and easy handling in the absence of biological risk. From a synthetic copolymer mainly based on DL-lactic acid a new skin substitute was developed, marketed as Suprathel. Within the scope of a bicentric study Suprathel was compared versus paraffin gauze intraindividually applied on split skin donor sites. Wound pain was measured on the Visual Pain Analog Scale over a period of 10 days as the critical criterion. Accordingly Suprathel versus Omiderm were compared on second degree burns (degree 2a, partial thickness burns). In both study parts, Suprathel significantly reduced pain. Its easy handling was superior compared to other materials. The Suprathel membrane adhered rapidly to the wound thus protecting against infections and promoting wound healing. No allergic reactions were observed. The ability of the material to resorb ensured pain-free removal after complete healing of the wound.

Effect of placental-extract gel and cream on non-healing wounds

OBJECTIVE

To compare the effects of topical placental-extract gel and cream in the treatment of chronic non-healing wounds with regard to wound healing and discomfort during dressing change.

METHODS

A sample of 120 patients attending the wound clinic at University Hospital, Varanasi, India, with wounds of more than six weeks' duration were enrolled into the study. They were alternately allocated to group A (topical application of placental-extract gel) or group B (placental-extract cream). Wound biopsy was performed, and swab culture and sensitivity were taken. Wound size was measured, and visual analogue scale (VAS) scores for pain and discomfort at dressing change were recorded at weekly follow-up in both groups. Biopsy was repeated after two weeks of treatment and sent for histopathological examination for assessment of angiogenesis in 25 cases from each group.

RESULTS

One hundred patients completed the study. More than 50% wound healing was observed after eight weeks in 72% of group A patients and 74% of group B patients (p = 0.75). Microscopic angiogenesis grading system (MAGS) scores were similar in both groups (not statistically significant, p = 0.92). The VAS scores for pain and discomfort were lower in group B (statistically significant, p < 0.02).

CONCLUSION

Placental-extract gel and cream are both effective topical agents for chronic non-healing wounds. However, there is less pain and discomfort during dressing change with the placental-extract cream, which we thus recommend for topical application in chronic non-healing wounds.

New technologies for burn wound closure and healing--review of the literature

Methods for handling burn wounds have changed in recent decades. Increasingly, aggressive surgical approach with early tangential excision and wound closure is being applied leading to improvement in mortality rates of burn victims. Autografts from uninjured skin remain the mainstay of treatment. Autologous skin graft, however, has limited availability and is associated with additional morbidity and scarring. Severe burn patients invariably lack sufficient adequate skin donor sites requiring alternative methods of skin replacement. The present review summarizes available replacement technologies.

A review of keratinocyte delivery to the wound bed

Over the last 20 years, confluent sheets of cultured epithelial autograft have been used for patients with major burns. Problems with the lack of "take" and long-term durability, as well as the time delay to produce such grafts, have led to the development of delivery systems to transfer keratinocytes to the wound bed. This review article describes the problems of using cultured epithelial autograft and the advantages of using preconfluent keratinocytes. Despite the numerous delivery systems that have been reported, most studies are limited to animal wound bed models. There are a few small clinical studies that have demonstrated enhanced healing using mainly subjective methods. There is a need for controlled, randomized clinical trials to prove the efficacy of keratinocyte delivery systems. Proposals for the use of this technology are made.

A trial to determine the role of placental extract in the treatment of chronic non-healing wounds

OBJECTIVE

To investigate the effect of topical placental extract in the treatment of non-healing wounds.

METHOD

One hundred patients attending the wound clinic at University Hospital, Varanasi, India, with wounds of more than six weeks' duration were recruited. Fifty patients were treated with placental extract, and 50 were controls. Wound biopsy and swab culture and sensitivity were performed and the area surrounding the wound was X-rayed. Wound size was measured and the rate of epithelialisation assessed at weekly follow-ups. In nine cases biopsies were repeated after two weeks of treatment and sent for histopathological examination, including angiogenesis.

RESULTS

Thirty patients dropped out, leaving 40 cases in the treatment group and 30 in the control group. Over an eight-week period, 27 patients (67.5%) in the treatment group showed more than 50% epithelialisation, compared with only seven patients (23.3%) in the control group.

CONCLUSION

Placental extract has a beneficial role to play as a topical agent in the management of chronic non-healing wounds.

The amniotic membrane in ophthalmology

The amniotic membrane is the innermost of the three layers forming the fetal membranes. It was first used in 1910 in skin transplantation. Thereafter it has been used in surgical procedures related to the genito-urinary tract, skin, brain, and head and neck, among others. The first documented ophthalmological application was in the 1940s when it was used in the treatment of ocular burns. Following initial reports, its use in ocular surgery abated until recently when it was re-discovered in the Soviet Union and South America. Its introduction to North America in the early 1990s heralded a massive surge in the ophthalmic applications of this membrane. The reintroduction of amniotic membrane in ophthalmic surgery holds great promise; however, although it has been shown to be a useful and viable alternative for some conditions, it is currently being used far in excess of its true useful potential. In many clinical situations it offers an alternative to existing management options without any distinct advantage over the others. Further studies will undoubtedly reveal the true potential of the membrane, its mechanism(s) of action, and the effective use of this tissue in ophthalmology.

Comparison of equine amnion and a nonadherent wound dressing material for bandaging pinch-grafted wounds in ponies

OBJECTIVE

To evaluate healing of pinch-grafted wounds on the distal aspect of the limbs of ponies bandaged with equine amnion or a standard nonadherent wound dressing material.

ANIMALS

6 ponies.

PROCEDURE

A 2.5x2.5-cm full-thickness section of skin was removed from the dorsal aspect of each limb at the midpoint of the metacarpus or metatarsus. Six days later, wounds were grafted with partial-thickness pinch grafts. Half the wounds were bandaged with amnion, and the other half were bandaged with a nonadherent dressing. Bandages were changed every 3 days until wound healing was complete. At each bandage change, numbers of grafts lost were recorded, and wounds were measured.

RESULTS

Percentage of grafts lost from wounds bandaged with amnion was not significantly different from percentage lost from wounds bandaged with the nonadherent dressing. Median healing time for wounds bandaged with amnion (30 days) was significantly less than median healing time for wounds bandaged with the nonadherent dressing (39 days). All wounds were healed by day 45.

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggest that amnion can be used for bandaging pinch-grafted wounds on the distal aspect of the limbs of ponies.

Effectiveness of human amnion preserved long-term in glycerol as a temporary biological dressing

Human amnion as a temporary biological wound dressing has remained a beneficial and cost-effective means of treating burns in developing countries. The aim of this study was to determine whether human amnion that has undergone long-term preservation in glycerol is an effective biological dressing compared to fresh amnion and glycerol-preserved human skin. Samples of human amnion and skin were preserved in sterile containers of 85% glycerol at 4 degrees C for over a year. Dorsal full-thickness or split-thickness skin wounds were produced in rats. The defects were divided into four areas, each of which was covered with preserved amnion, fresh amnion, preserved skin, or left uncovered as a control. The materials on the wounds were evaluated macroscopically and microscopically after 2, 4, 7, 10 and 14 days. The primary take or adherence of the grafts on full-thickness wounds was evaluated at 4 and 7 days, and material performance was scored based on several macroscopic and microscopic criteria. The bacteria levels reducing effect of the materials were examined by quantitative bacteriology in heavily infected full-thickness scald burn wounds of rats. Qualitative cultures confirmed that the storage conditions the materials were subjected to for over a year were aseptic and that the amnion and skin had maintained their characteristic properties. All materials were found effective on partial-thickness rat wounds as a cover under which re-epithelialization was completed by 7 days. The preserved skin performed better than either preserved or fresh amnion on full-thickness wounds but the performance of preserved amnion was comparable to that of fresh amnion. Glycerol-preserved amnion was found to be as effective as fresh amnion or skin in terms of decreasing bacterial levels in infected rat burn wounds. Amnion stored in glycerol is reliable and effective for a long period of time. Amnion banking could provide an unlimited quantity of biologic dressing for burn treatment at low cost, a factor that is particularly important in developing countries.