The Use of Dehydrated Human Amnion/Chorion Membranes in the Treatment of Burns and Complex Wounds: Current and Future Applications

Assessment of the proteome profile of decellularized human amniotic membrane and its biocompatibility with umbilical cord-derived mesenchymal stem cells

Extracellular matrix-based bio-scaffolds are useful for tissue engineering as they retain the unique structural, mechanical, and physiological microenvironment of the tissue thus facilitating cellular attachment and matrix activities. However, considering its potential, a comprehensive understanding of the protein profile remains elusive. Herein, we evaluate the impact of decellularization on the human amniotic membrane (hAM) based on its proteome profile, physicochemical features, as well as the attachment, viability, and proliferation of umbilical cord-derived mesenchymal stem cells (hUC-MSC). Proteome profiles of decellularized hAM (D-hAM) were compared with hAM, and gene ontology (GO) enrichment analysis was performed. Proteomic data revealed that D-hAM retained a total of 249 proteins, predominantly comprised of extracellular matrix proteins including collagens (collagen I, collagen IV, collagen VI, collagen VII, and collagen XII), proteoglycans (biglycan, decorin, lumican, mimecan, and versican), glycoproteins (dermatopontin, fibrinogen, fibrillin, laminin, and vitronectin), and growth factors including transforming growth factor beta (TGF-β) and fibroblast growth factor (FGF) while eliminated most of the intracellular proteins. Scanning electron microscopy was used to analyze the epithelial and basal surfaces of D-hAM. The D-hAM displayed variability in fibril morphology and porosity as compared with hAM, showing loosely packed collagen fibers and prominent large pore areas on the basal side of D-hAM. Both sides of D-hAM supported the growth and proliferation of hUC-MSC. Comparative investigations, however, demonstrated that the basal side of D-hAM displayed higher hUC-MSC proliferation than the epithelial side. These findings highlight the importance of understanding the micro-environmental differences between the two sides of D-hAM while optimizing cell-based therapeutic applications.

The role of macrophage polarization in tendon healing and therapeutic strategies: Insights from animal models

Tendon injuries, a common musculoskeletal issue, usually result in adhesions to the surrounding tissue, that will impact functional recovery. Macrophages, particularly through their M1 and M2 polarizations, play a pivotal role in the inflammatory and healing phases of tendon repair. In this review, we explore the role of macrophage polarization in tendon healing, focusing on insights from animal models. The review delves into the complex interplay of macrophages in tendon pathology, detailing how various macrophage phenotypes contribute to both healing and adhesion formation. It also explores the potential of modulating macrophage activity to enhance tendon repair and minimize adhesions. With advancements in understanding macrophage behavior and the development of innovative biomaterials, this review highlights promising therapeutic strategies for tendon injuries.

Human amniotic membranes as an allogenic biological dressing for the treatment of burn wounds: Protocol for a randomized-controlled study

Background

Burn wounds pose significant challenges in medical treatment due to their devastating nature and resource-intensive requirements. Temporary coverage of burn wounds using synthetic or biological dressings allows for reepithelization before definitive skin grafting. Allogenic skin grafts have been widely used but come with drawbacks such as rejection and disease transmission. The use of amniotic membranes (AMs) offers a promising alternative for temporary coverage, as they possess biological properties that promote faster healing and improved scar quality. The various components of the amniotic membrane, including pluripotent stem cells, extracellular matrix proteins, and regenerative factors, contribute to cell growth, migration, and differentiation, as well as preservation of the original epithelial phenotype.

Objective

Reliable information on the treatment of burn wounds with AM is needed. The knowledge gained in this project may help to include this advantageous modern concept of biological dressings in clinical practice. The purpose of this study is to use human amniotic membranes from our in hospital laboratory, as an allogenic biological dressing after enzymatic debridement in superficial partial thickness, deep partial thickness or full thickness burn wounds.

Methods

We will include 30 patients in a randomized-controlled trial with each patient receiving the study intervention and the control intervention. Two 7 × 7 cm burn wound areas will be compared regarding percentage of skin graft take, healing time, healing percentage value and total healing time. Human amniotic membranes will be compared to allogenic skin grafts.

The Preparation and Clinical Efficacy of Amnion-Derived Membranes: A Review

Biological tissues from various anatomical sources have been utilized for tissue transplantation and have developed into an important source of extracellular scaffolding material for regenerative medicine applications. Tissue scaffolds ideally integrate with host tissue and provide a homeostatic environment for cellular infiltration, growth, differentiation, and tissue resolution. The human amniotic membrane is considered an important source of scaffolding material due to its 3D structural architecture and function and as a source of growth factors and cytokines. This tissue source has been widely studied and used in various areas of tissue repair including intraoral reconstruction, corneal repair, tendon repair, microvascular reconstruction, nerve procedures, burns, and chronic wound treatment. The production of amniotic membrane allografts has not been standardized, resulting in a wide array of amniotic membrane products, including single, dual, and tri-layered products, such as amnion, chorion, amnion-chorion, amnion-amnion, and amnion-chorion-amnion allografts. Since these allografts are not processed using the same methods, they do not necessarily produce the same clinical responses. The aim of this review is to highlight the properties of different human allograft membranes, present the different processing and preservation methods, and discuss their use in tissue engineering and regenerative applications.

Membrane barriers for guided bone regeneration: An overview of available biomaterials

Dental implants revolutionized the treatment options for restoring form, function, and esthetics when one or more teeth are missing. At sites of insufficient bone, guided bone regeneration (GBR) is performed either prior to or in conjunction with implant placement to achieve a three-dimensional prosthetic-driven implant position. To date, GBR is well documented, widely used, and constitutes a predictable and successful approach for lateral and vertical bone augmentation of atrophic ridges. Evidence suggests that the use of barrier membranes maintains the major biological principles of GBR. Since the material used to construct barrier membranes ultimately dictates its characteristics and its ability to maintain the biological principles of GBR, several materials have been used over time. This review, summarizes the evolution of barrier membranes, focusing on the characteristics, advantages, and disadvantages of available occlusive barrier membranes and presents results of updated meta-analyses focusing on the effects of these membranes on the overall outcome.

Cryopreserved amniotic membrane in the treatment of limb skin defects of aplasia cutis congenita: a case study

OBJECTIVE

To report the efficacy and long-term outcomes of treating the skin defects of aplasia cutis congenita (ACC) with cryopreserved amniotic membrane (AM).

METHOD

Human amnion was obtained from the caesarean delivery of a full-term healthy pregnancy and processed in a sterile laminar flow hood, and cryopreserved in liquid nitrogen. The structure of the AM was investigated histologically and the viability of the epithelial cells was assessed after cryopreservation and compared with fresh AM and with AM preserved in phosphate-buffered saline (PBS) at 4°C. The cryopreserved AM was applied onto the lower limb skin defects of a one-month old baby with ACC. Timely AM changes were performed as necessary until the wounds healed.

RESULTS

The structure of the cryopreserved AM was intact, with little visible difference compared with fresh AM. The viability of the epithelial cells was partially lost but still much better retained than in those preserved in PBS at 4°C. The limb skin defects were gradually re-epithelialised upon application of the AM and were completely healed after one month. The 4-month and 2-year follow-ups presented good skin texture and colour, without hypertrophic scar formation.

CONCLUSION

In this case study, cryopreservation of AM presented a well preserved stromal compartment and viable epithelial layer. It also offered features such as pain relief, good attachment and adhesiveness, improved wound healing and suppressed scar formation in the treatment of ACC skin defects.

Biophysical Characterization of a Novel Tri-Layer Placental Allograft Membrane

Objective: Placental tissues, including membranes composed of amnion and chorion, are promising options for the treatment of chronic wounds. Amnion and chorion contain multiple extracellular matrix (ECM) proteins and a multitude of growth factors and cytokines that, when used clinically, assist in the progression of difficult to heal wounds through restoration of a normal healing process. The objective of this study was to characterize the in vitro physical and biological properties of a dehydrated tri-layer placental allograft membrane (TPAM) consisting of a chorion layer sandwiched between two layers of amnion. Approach: Mechanical properties were evaluated by mechanical strength and enzyme degradation assays. The ECM composition of TPAM membranes was evaluated by histological staining while growth factors and cytokine presence was evaluated by a multiplex enzyme-linked immunosorbent assay. Proliferation, migration, and ECM secretion assays were performed with fibroblasts. Immunomodulatory properties were assessed by a pro-inflammatory cytokine reduction assay while the macrophage phenotype was determined by quantifying the ratio of M1 versus M2 secreted factors. Results: The unique three-layer construction improves mechanical handling properties over single- and bi-layer membranes. Results demonstrate that TPAM is rich in ECM proteins, growth factors, cytokines, and tissue inhibitors of metalloproteinases, and favorably influences fibroblast migration, proliferation, and ECM secretion when compared to negative controls. Furthermore, after processing and preservation, these membranes maintain their intrinsic immunomodulatory properties with the ability to suppress pro-inflammatory processes and modulate the M1 and M2 macrophage phenotype toward a pro-regenerative profile when compared to a negative control. Innovation: This is the first study to characterize both the biophysical and biological properties of a tri-layer placental membrane. Conclusion: This work demonstrates that TPAM has improved handling characteristics over single- and bi-layer membranes, stimulates pro-healing cellular responses, and advantageously modulates inflammatory responses, altogether making this scaffold a promising option for treating wounds, especially those that are complex or difficult to heal.

Dehydrated human amnion/chorion membrane allografts for myelomeningocele and wound reconstruction

A growing body of literature demonstrates the clinical promise of dehydrated human amnion/chorion membrane (dHACM), a cryopreserved tissue product derived from placental amniotic membrane, to enhance post-operative wound healing. The purpose of this study is to review the potential of dHACM to facilitate post-surgical and myelomeningocele wound repair. A comprehensive literature search of PubMed was conducted to identify studies investigating dHACM use in pediatric and surgical wound care published from inception to October 2020. For each study, patient characteristics, wound characteristics, and outcomes following dHACM application were documented and assessed. Of the 190 articles reviewed, 15 publications were included in the final analysis. Results demonstrated that the average wound healing time varied across clinical indications (e.g., 14 days for trauma reconstruction to 116 days for Moh's surgery repair). Across indications, pediatric patients had shorter healing periods compared to adults (P < 0.01). Chronic wounds (> four weeks old) were documented in both adult (n = 3) and pediatric (n = 2) wound repair publications; all chronic surgical wounds demonstrated complete wound closure with dHACM. No complications from dHACM use were reported. Advantages of dHACM included increased patient satisfaction, cost-savings, and faster wound healing. We then present two cases of myelomeningocele wound repair facilitated successfully by dHACM. Overall, dHACM proves to successfully expedite wound repair in pediatric patients with chronic or complicated wounds such as those from myelomeningocele repair. It is important for surgeons to consider wound duration, size, and patient age to better predict graft success in enhancing wound repair.

Comparative evaluation of the efficacy of wound healing with and without dehydrated human amniotic/chorionic membrane in alveoloplasty: a pilot study

Objectives

Wound healing is an integral part of any surgical procedure. Appropriate wound closure is critical to any successful surgical procedure, especially intraoral procedures. Various factors aid in wound healing, both pharmacological and non-pharmacological. Dehydrated human amniotic/chorionic membrane (dHACM) is an emerging bioinert material that contains anti-inflammatory properties, angiogenetic properties, osteogenic potential, and various growth factors. The purpose of this study was to evaluate the efficacy of wound healing properties of dHACM in bilateral alveoloplasty patients.

Materials and Methods

A prospective split-mouth study was conducted on 10 patients. Site A received sutures with dHACM and site B was sutured without dHACM. Wound healing was assessed with the Landry, Turnbull, and Howley Index.

Results

Sites A and site B were compared. A P<0.05 and a test value of 22 was obtained, indicating a statistical difference between the two sites.

Conclusion

Our study showed better healing with dHACM than without.

Biofabrication of allogenic bone grafts using cellularized amniotic scaffolds for application in efficient bone healing

INTRODUCTION

The reconstruction/regeneration of human bone injuries/defects represents a crucial challenge due to the lack of suitable bio/immune compatible and implantable biological grafts. The available strategies represent implications of several types of grafting materials in the form of metals, synthetic, and various kinds of biological scaffolds; however, the lack of appropriate biological components required for activating and enhancing repair mechanisms at the lesion-site limits their wider applicability.

METHODS

In this study, a unique approach for generating human osteogenic implantable grafts was developed using biofabrication technology. Using a gradient change of detergents and continuous agitation, developed a unique technique to generate completely cell-free amnion and chorion scaffolds. The absence of cellular components and integrity of biological and mechanical cues within decellularized human amnion (D-HAM) and chorion (D-HCM) were evaluated and compared with fresh membranes. Allogenic bone grafts were prepared through induction of human mesenchymal stem cells (hMSCs) into osteogenic cells on D-HAM and D-HCM and evaluated for their comparative behavior at the cellular, histological and molecular levels.

RESULTS

The common decellularization process resulted in an efficient way to generate D-HAM and D-HCM while retaining their intact gross-anatomical architecture, surface morphology, extracellular matrix components, and mechanical properties. Both these scaffolds supported better growth of human umbilical cord blood derived MSCs as well as osteogenic differentiation. Comparative investigation revealed better growth rate and differentiation on D-HCM compared to D-HAM and control conditions.

CONCLUSION

D-HCM could be used as a better choice for producing suitable allogenic bone grafts for efficient bone healing applications.

Clinical and cost efficacy of advanced wound care matrices in the treatment of venous leg ulcers: a systematic review

BACKGROUND

Venous leg ulcers (VLUs) are hard-to-heal, recurrent and challenging to treat. Advanced wound care matrices (AWCMs) have been developed to supplement conventional therapies. These costly AWCMs warrant careful comparison as healthcare expenditures are subjected to increasing scrutiny.

AIM

This study was designed to compare AWCMs in their ability to heal VLUs and their cost efficacy through a systematic review of randomised controlled trials (RCTs).

METHOD

An organised search of Medline, Cochrane Library, Central and CINAHL databases identified RCTs that compared AWCMs to standard compression therapy in the healing of VLUs. Bias was assessed using the Effective Public Health Practice Project (EPHPP) Quality Assessment Tool for Quantitative Studies. Eight studies analysing bilayered skin substitute (BSS) (Apligraf), dehydrated human amnion/chorion membrane (dHACM) (Epifix), human fibroblast-derived dermal substitute (HFDDS) (Dermagraft), extracellular wound matrix (ECM) (Oasis), advanced matrix (AM) (Talymed) and matrix wound dressing (MWD) (Promogran) met the inclusion criteria.

RESULTS

Four studies reported significant improvement over standard therapy: BSS, dHACM, ECM and AM. Incremental cost per additional successful treatment was determined for each trial, ranging from $2593 (MWD) to $210,800 (HFDDS).

CONCLUSION

Our consolidated analysis of eight major RCTs of AWCMs in the treatment of VLUs revealed a great variation in clinical and cost efficacy among these products. The included trials were inconsistent in methodology, and these limitations should be noted, but, in the absence of RCTs to compare these products, our systematic review may serve as a guide for practitioners who seek to optimise wound healing while considering cost efficacy.

Antimicrobial Activity of Human Fetal Membranes: From Biological Function to Clinical Use

The fetal membranes provide a supportive environment for the growing embryo and later fetus. Due to their versatile properties, the use of fetal membranes in tissue engineering and regenerative medicine is increasing in recent years. Moreover, as microbial infections present a crucial complication in various treatments, their antimicrobial properties are gaining more attention. The antimicrobial peptides (AMPs) are secreted by cells from various perinatal derivatives, including human amnio-chorionic membrane (hACM), human amniotic membrane (hAM), and human chorionic membrane (hCM). By exhibiting antibacterial, antifungal, antiviral, and antiprotozoal activities and immunomodulatory activities, they contribute to ensuring a healthy pregnancy and preventing complications. Several research groups investigated the antimicrobial properties of hACM, hAM, and hCM and their derivatives. These studies advanced basic knowledge of antimicrobial properties of perinatal derivatives and also provided an important insight into the potential of utilizing their antimicrobial properties in a clinical setting. After surveying the studies presenting assays on antimicrobial activity of hACM, hAM, and hCM, we identified several considerations to be taken into account when planning future studies and eventual translation of fetal membranes and their derivatives as antimicrobial agents from bench to bedside. Namely, (1) the standardization of hACM, hAM, and hCM preparation to guarantee rigorous antimicrobial activity, (2) standardization of the antimicrobial susceptibility testing methods to enable comparison of results between various studies, (3) investigation of the antimicrobial properties of fetal membranes and their derivatives in the in vivo setting, and (4) designation of donor criteria that enable the optimal donor selection. By taking these considerations into account, future studies will provide crucial information that will enable reaching the optimal treatment outcomes using the fetal membranes and their derivatives as antimicrobial agents.

Acute Reconstruction of Periorbital Trauma Resulting in Eyelid Anterior Lamella Loss With Simultaneous Full-thickness Skin Grafting and Amniotic Membrane Grafting: A Case Report

Complex facial lacerations are frequently encountered in the combat environment. Trauma with soft-tissue loss of the periorbital region offers particular challenges in terms of operative reconstruction. Cicatricial changes in the sub-acute phase can lead to eyelid malposition and lagophthalmos. The authors present a novel technique for acute reconstruction of periorbital trauma with eyelid soft-tissue loss with simultaneous full-thickness skin grafting and amniotic membrane grafting. The technique involves standard preparation of the surgical area of injury and infiltration with local anesthetic. Initially, the area of injury is copiously irrigated, and debridement of any necrotic tissue is accomplished. Amniotic membrane grafting is then performed over the defect. Approximately 2 mm × 2 mm full-thickness skin grafts are procured and distributed over the initial amniotic membrane graft. A second amniotic membrane graft is then secured over the skin graft-amniotic membrane graft complex with cyanoacrylate tissue adhesive. A bolstered suture tarsorrhaphy is performed to minimize tissue trauma during the healing process. The operative and postsurgical outcomes were assessed. The graft site healed well without cicatricial changes or lagophthalmos. Peripheral small papillomatous lesions did develop requiring excision for cosmesis, but ultimately the graft site demonstrated appropriate coverage and healthy re-epithelialization over the previous defect. This case demonstrates the viability of simultaneous full-thickness skin grafting with concomitant amniotic membrane grafting for the acute reconstruction of periorbital trauma with eyelid anterior lamella tissue loss. An excellent cosmetic and functional outcome was attained. By providing acute reconstruction, the risk of damage secondary to cicatricial periorbital changes may be avoided.

[Application of medical biomaterials in prevention and treatment of tendon adhesion]

OBJECTIVE

To review the research progress of medicine biomaterials in prevention and treatment of adhesion after tendon injury, and to provide reference for clinical treatment.

METHODS

The literature on the application of medical biomaterials in the prevention and treatment of tendon adhesions in recent years was reviewed, and the biological process, treatment methods, and current status of tendon adhesions were summarized.

RESULTS

Tendon adhesion as part of the healing process of the tendon is the biological response of the tendon to the injury and is also a common complication of joint dysfunction. Application of medical biomaterials can achieve better biological function of postoperative tendon by reducing the adhesion of peritendon tissues as far as possible without adversely affecting the tendon healing process.

CONCLUSION

The use of medical biomaterials is conducive to reduce the adhesion of tendon after operation, and the appropriate anti-adhesion material should be selected according to the patients' condition and surgical needs.

Using Dehydrated Amniotic Membrane Skin Substitute in Facial Burns: Is There a Outcome Difference Between Adult and Pediatric Patients?

INTRODUCTION

Facial burns have significant physical and psychological effects on patients, and minimizing morbidity continues to be a challenge for reconstructive surgeons. Advancements have allowed the development of various skin substitutes. Among these, human dehydrated amniotic skin substitutes represent novel technology, yet their outcome has not been sufficiently studied to guide practice. The objective of our study is to compare the safety of amniotic membrane skin substitutes in the treatment of adult and pediatric facial burns.

METHODS

The authors performed a retrospective review of our institutional burn registry, with 90 burn patients meeting the inclusion criteria. Demographic and outcome measures included age, percentage of total body surface area (TBSA), Injury Severity Score (ISS), and complications (eg, pigmentation, hypertrophic scar, infection, and delayed healing). Paired sample t test and Chi-squared test were used, with significance defined as P < 0.05.

RESULTS

Seventy-seven adults and 13 pediatric patients with facial burns who had received dehydrated amniotic membrane skin substitutes were included in the analysis. The mean age was 40.8 years for adults and 5.6 years for children. Mean TBSA was similar, with 9.6% (1-57%) in adults and 6.0% (2-14%) in children. The mean ISS did not significantly differ between groups (4.0 versus 2.2, P = ns). Pediatric patients with facial burns treated with amniotic membranes had a higher incidence of dyspigmentation relative to adult patients (46.2% versus 9.1%, P ≤ 0.05). Remaining morbidities were not significantly different between adult and pediatric patients. All patients, irrespective of group, healed by the second post-operative week.

CONCLUSION

Dehydrated amniotic membrane skin substitutes are a safe alternative in the treatment of facial burns across all ages.

Lung Surfactant Accelerates Skin Wound Healing: A Translational Study with a Randomized Clinical Phase I Study

Lung surfactants are used for reducing alveolar surface tension in preterm infants to ease breathing. Phospholipid films with surfactant proteins regulate the activity of alveolar macrophages and reduce inflammation. Aberrant skin wound healing is characterized by persistent inflammation. The aim of the study was to investigate if lung surfactant can promote wound healing. Preclinical wound models, e.g. cell scratch assays and full-thickness excisional wounds in mice, and a randomized, phase I clinical trial in healthy human volunteers using a suction blister model were used to study the effect of the commercially available bovine lung surfactant on skin wound repair. Lung surfactant increased migration of keratinocytes in a concentration-dependent manner with no effect on fibroblasts. Significantly reduced expression levels were found for pro-inflammatory and pro-fibrotic genes in murine wounds. Because of these beneficial effects in preclinical experiments, a clinical phase I study was initiated to monitor safety and tolerability of surfactant when applied topically onto human wounds and normal skin. No adverse effects were observed. Subepidermal wounds healed significantly faster with surfactant compared to control. Our study provides lung surfactant as a strong candidate for innovative treatment of chronic skin wounds and as additive for treatment of burn wounds to reduce inflammation and prevent excessive scarring.

The Use of Dehydrated Human Amniotic/Chorionic Membrane Skin Substitute in the Treatment of Pediatric Facial Burn

BACKGROUND

Facial burns have lasting physical and psychological effects on pediatric patients. Proper management to minimize morbidities challenges reconstructive surgeons. New technologies allowed the development of skin substitutes such as amniotic and chorionic membranes, yet the use of these skin dressings and their impact on burn outcomes have not been sufficiently studied to guide practices. The objective of this study is to report on the outcomes of dehydrated amniotic membrane as a biologic skin dressing in pediatric facial burn injury compared to cadaveric allografts.

METHODS

Retrospective review of data collected from our institutional burn registry from 2012 to 2016. The study population included patients younger than 16 years with facial burns. Patients between 2012 and 2014 received cadaveric allografts, whereas during 2015 to 2016 patients received dehydrated human amniotic/chorionic membrane as standard treatment. Demographic characteristics and outcome measures were compared between the 2 groups.

RESULTS

Included 30 patients with a mean age of 3.7 years and with an average total body surface area burn of 6.8% (2%-27%). Mean injury severity scores did not significantly differ between both groups, 1.8 in amniotic group versus 2.3 in cadaveric skin group (P > 0.05). There were 4 complications (3 hypertrophic scars and 1 wound infection) in the cadaveric allografts group versus no complications in the amniotic membrane group (P < 0.05).

CONCLUSION

Dehydrated amniotic/chorionic membrane wound dressings are a safe alternative to cadaveric allografts in treating pediatric partial thickness facial burns.

Biological Amnion Prevents Flexor Tendon Adhesion in Zone II: A Controlled, Multicentre Clinical Trial

Introduction

Tendon adhesion to surrounding tissues is the most common complication reported after tendon repair. To date, effective solutions to prevent tendon injury are still lacking.

Materials and Methods

A total of 89 patients with flexor tendon injury in zone II were recruited. The patients were divided into a control group, a poly-DL-lactic acid (PDLLA) group, and an amnion group according to the different tendon treatments applied. The control group was not subjected to other treatments. PDLLA and bioamniotic membranes were, respectively, used to wrap broken ends in the PDLLA and amnion membrane groups. The patients were followed at 1, 2, 3, 6, and 12 months after surgery and the ranges of active flexion and extension lag in the proximal and distal interphalangeal joints were evaluated.

Results

The means of total active ranges of motion of the interphalangeal joints (excluding rupture cases) in the PDLLA and amnion groups did not significantly differ between each other but significantly differed from that of the control group. Statistical analysis showed a significant difference in the clinical grades of the outcomes among the control, PDLLA, and amnion groups. The incidence of complications in the control and PDLLA groups was found to be significantly higher than that in the amniotic membrane group; no significant difference was observed between the control and PDLLA groups.

Conclusion

In this study, freeze-dried amniotic membrane transplantation was applied to promote healing of the flexor tendon in zone II and prevent adhesion. This technique presents a new method to solve the issue of tendon adhesion after repair.

Clinical Trial Registration

The trial was registered by identifier ChiCTR1900021769.

Novel pharmacotherapy for burn wounds: what are the advancements

INTRODUCTION

The prognosis for severe burns has improved significantly over the past 50 years. Meanwhile, burns have become an affliction mainly affecting the less well-developed regions of the world. Early excision and skin grafting has led to major improvements in therapeutic outcomes.

AREAS COVERED

The purpose of this article is to survey the use of pharmacotherapy to treat different pathophysiological complications of burn injury. The author, herein, discusses the use of drug treatments for a number of systemic metabolic disturbances including hyperglycemia, elevated catabolism, and gluconeogenesis.

EXPERT OPINION

Advancements in personalized and molecular medicine will make an impact on burn therapy. Similarities between severe burns and other critically ill patients will lead to cross-fertilization between different medical specialties. Furthermore, advances in stem cells and tissue regeneration will lead to improved healing and less lifelong disability. Indeed, research in new drug therapy for burns is actively progressing for many different complications.

Experimental study of tendon sheath repair via decellularized amnion to prevent tendon adhesion

The adhesion of tendon and surrounding tissue is the most common complication after repairing an injured tendon. The injured flexor tendons in zone II are frequently accompanied by tendon sheath defects, which lead to poor recovery. A variety of biological and non-biological materials have been recently used for repair or as substitute for tendon sheaths to prevent tendon adhesion. However, non-biological materials, such as polyethylene films, have been used to prevent tendon adhesions by mechanical isolation. The possibility of tendon necrosis and permanent foreign body remains due to the lack of permeability and the obstruction of nutrient infiltration. The natural macromolecule amniotic membrane derived from organisms is a semi-permeable membrane with the following characteristics: smooth; without vascular, nerve, and lymphatic; and rich in matrix, cytokines, enzymes, and other active ingredients. The unique structure of this membrane makes it an ideal biomaterial. In the experiment in Henry chicken, the model of tendon sheath defect and the flexor digitorum tendon in zone II was established and randomly divided into control group, medical membrane group, and decellularized amniotic membrane group. Samples were obtained at the 2nd, 4th, 8th, and 12th week after operation. General, histological, and biomechanical tests were performed to investigate the preventive effect of repaired tendon sheath by decallularized amniotic membrane. Experimental results showed the following: the amniotic membrane group and the medical membrane group had mild inflammatory reaction and tissue edema, and nearly no adhesion was observed in the surrounding tissue; the fibroblast-like cells were distributed in layers under the light microscope; the amniotic membrane group was denser than the medical membrane group cells, and numerous fibroblasts were disorganized in the control group. Biomechanical measurements showed that the sliding distance of tendon, the total flexion angle of the toes, and the tendon maximum tensile breaking strength at the early postoperative were significantly better than in the control group. Through this experiment, the amniotic membrane, as a natural biological substitute material in the construction of tendon sheath, can effectively inhibit exogenous healing and promote endogenous healing to prevent tendon adhesion.

Advancements in Regenerative Strategies Through the Continuum of Burn Care

Burns are caused by several mechanisms including flame, scald, chemical, electrical, and ionizing and non-ionizing radiation. Approximately half a million burn cases are registered annually, of which 40 thousand patients are hospitalized and receive definitive treatment. Burn care is very resource intensive as the treatment regimens and length of hospitalization are substantial. Burn wounds are classified based on depth as superficial (first degree), partial-thickness (second degree), or full-thickness (third degree), which determines the treatment necessary for successful healing. The goal of burn wound care is to fully restore the barrier function of the tissue as quickly as possible while minimizing infection, scarring, and contracture. The aim of this review is to highlight how tissue engineering and regenerative medicine strategies are being used to address the unique challenges of burn wound healing and define the current gaps in care for both partial- and full-thickness burn injuries. This review will present the current standard of care (SOC) and provide information on various treatment options that have been tested pre-clinically or are currently in clinical trials. Due to the complexity of burn wound healing compared to other skin injuries, burn specific treatment regimens must be developed. Recently, tissue engineering and regenerative medicine strategies have been developed to improve skin regeneration that can restore normal skin physiology and limit adverse outcomes, such as infection, delayed re-epithelialization, and scarring. Our emphasis will be centered on how current clinical and pre-clinical research of pharmacological agents, biomaterials, and cellular-based therapies can be applied throughout the continuum of burn care by targeting the stages of wound healing: hemostasis, inflammation, cell proliferation, and matrix remodeling.

The enzymatic de-epithelialization technique determines denuded amniotic membrane integrity and viability of harvested epithelial cells

The human amniotic membrane (HAM) is widely used for its wound healing effect in clinical practice, as a feeder for the cell cultivation, or a source of cells to be used in cell therapy. The aim of this study was to find effective and safe enzymatic HAM de-epithelialization method leading to harvesting of both denuded undamaged HAM and viable human amniotic epithelial cells (hAECs). The efficiency of de-epithelialization using TrypLE Express, trypsin/ ethylenediaminetetraacetic (EDTA), and thermolysin was monitored by hematoxylin and eosin staining and by the measurement of DNA concentration. The cell viability was determined by trypan blue staining. Scanning electron microscopy and immunodetection of collagen type IV and laminin α5 chain were used to check the basement membrane integrity. De-epithelialized hAECs were cultured and their stemness properties and proliferation potential was assessed after each passage. The HAM was successfully de-epithelialized using all three types of reagents, but morphological changes in basement membrane and stroma were observed after the thermolysin application. About 60% of cells remained viable using trypsin/EDTA, approximately 6% using TrypLE Express, and all cells were lethally damaged after thermolysin application. The hAECs isolated using trypsin/EDTA were successfully cultured up to the 5^th passage with increasing proliferation potential and decreased stem cell markers expression (NANOG, SOX2) in prolonged cell culture. Trypsin/EDTA technique was the most efficient for obtaining both undamaged denuded HAM and viable hAECs for consequent culture.