The use of human amnion/chorion membrane in the clinical setting for lower extremity repair: a review

Procurement, Processing, and Storage of Human Amniotic Membranes for Implantation Purposes in Non-Healing Pressure Ulcers

The human amniotic membrane (hAM) has been used as an implant to enhance the regenerative process and control inflammation in different diseases, given their structure, biocompatibility, presence of stem cells and multiple growth factors. The objective of this study was to generate a standardized protocol for obtaining, processing, and storing hAMs that guarantee the conservation of their structural and cellular characteristics as well as their mechanical properties, ensuring their ease of handling, sterility, and quality that allows their implementation for therapeutic purposes in the field of regenerative medicine. The hAMs were obtained from mothers with healthy, full-term, controlled pregnancies and by cesarean section. The hAMs were processed under sterile conditions, manually separated from the placenta and, subsequently, they were frozen in a solution of culture medium plus 50% v/v glycerol. The protocol allows obtaining sterile hAMs composed of both epithelium and stroma with adequate preservation of the amniotic cells. The glycerol's impact on the mechanical properties may enhance the membrane's adaptability and conformability to diverse wound surfaces, potentially improving the healing process. It is necessary to repeat microbiological, cell viability and mechanical studies at 6 and 12 months to ensure that long-term frozen conditions do not affect the quality of the hAMs.

Alginate-Based Hydrogels with Amniotic Membrane Stem Cells for Wound Dressing Application

Objective

Chronic wounds are a common clinical problem that necessitate the exploration of novel regenerative therapies. We report a method to investigate the in vitro wound healing capacity of an innovative biomaterial, which is based on amniotic membrane-derived stem cells (AMSCs) embedded in an alginate hydrogel matrix. The aim of this study was to prepare an sodium alginate-based hydrogel, cross-linked calcium chloride (CaCl2) with the active ingredient AMSC (AMSC/Alg-H) and to evaluate its in vitro effectiveness for wound closure.

Methods

This hydrogel preparation involved combining sterile solutions of AMSC, sodium alginate, and CaCl2, followed by rinsing with serum-free media. The cells were cultured in different 6-well plates, namely sodium alginate, calcium chloride, AMSC, Alg-H, and AMSC/Alg-H, in complete medium with 10% FBS. The hydrogel was successfully formulated, as confirmed by characterization techniques including Scanning Electron Microscopy (SEM), Fourier Transform Infrared (FTIR) spectroscopy, Differential Scanning Calorimetry (DSC), Cytotoxicity Studies, TGF-β1 Level Measurement by ELISA, and Cell Scratch Wound Assay.

Results

Cryo-EM characterization of the Alg-H preparation successfully demonstrated the encapsulation of MSCs. FTIR and DSC analyses indicate that crosslinking transpires in Alg-H encapsulating AMSC. The AMSC/Alg-H preparation showed no significant difference in toxicity compared to HaCaT cells (p < 0.05), indicating it was not toxic to HaCaT cells. Furthermore, in the scratch wound assay test at 24 hours, the AMSC/Alg-H preparation achieved 100% wound closure, outperforming both AMSC and Alg-H alone. In vitro assessment revealed that AMSC/Alg-H significantly enhanced key wound healing processes, including cell proliferation and migration, compared to Alg-H.

Conclusion

Our study demonstrated the promising potential of AMSC/Alg-H as an enhanced regenerative therapy for in vitro wound healing. AMSC/Alg-H was able to maintain the viability of AMSCs and facilitate the formation of tissue-like structures.

Dehydrated Human Amnion-Chorion Membrane as a Bioactive Scaffold for Dental Pulp Tissue Regeneration

The dehydrated human amnion-chorion membranes (dHACMs) derived from the human placenta have emerged as a promising biomaterial for dental pulp regeneration owing to their unique biological and structural properties. The purpose of this review is to explore the potentials of dHACMs in dental pulp tissue engineering, focusing on their ability to promote cellular proliferation, differentiation, angiogenesis, and neurogenesis. dHACMs are rich in extracellular matrix proteins and growth factors such as TGF-β1, FGF2, and VEGF. They also exhibit significant anti-inflammatory and antimicrobial properties, creating an optimal environment for dental pulp regeneration. The applications of dHACMs in regenerative endodontic procedures are discussed, highlighting their ability to support the formation of dentin and well-vascularized pulp-like tissue. This review demonstrates that dHACMs hold significant potential for enhancing the success of pulp regeneration and offer a biologically based approach to preserve tooth vitality and improve tooth survival. Future research is expected to focus on conducting long-term clinical studies to establish their efficacy and safety.

Refrigerated amniotic membrane maintains its therapeutic qualities for 48 hours

During wound healing, the migration of keratinocytes is critical for wound closure. The application of amniotic membrane (AM) on wounds with challenging contexts (e.g., chronification and diabetic foot ulcer) has proven very successful. However, the use of AM for clinical practice has several restraints when applied to patients; the most important restriction is preserving AM's therapeutic properties between its thawing and application onto the patient's wound. Moreover, AM collection and processing requires a cleanroom, together with specialized staff and equipment, and facilities that are not usually available in many hospitals and healthcare units. In this publication, we kept previously cryopreserved AM at different temperatures (37°C, 20°C, and 4°C) in different media (DMEM high glucose and saline solution with or without human albumin) and for long incubation time periods after thawing (24 h and 48 h). HaCaT keratinocytes and TGF-β1-chronified HaCaT keratinocytes were used to measure several parameters related to wound healing: migration, cell cycle arrest rescue, and the expression of key genes and migration-related proteins. Our findings indicate that AM kept in physiological saline solution at 4°C for 24 h or 48 h performed excellently in promoting HaCaT cell migration compared to AM that had been immediately thawed (0 h). Indeed, key proteins, extracellular signal-regulated kinase (ERK) and c-Jun, were induced by AM at 4°C in saline solution. Similarly, cell proliferation and different genes related to survival, inflammation, and senescence had, in all cases, the same response as to standard AM. These data suggest that the handling method in saline solution at 4°C does not interfere with AM's therapeutic properties.

Advances and impact of human amniotic membrane and human amniotic-based materials in wound healing application

Wound healing is a complicated process, especially when surgical, traumatic, burn, or pathological injury occurs, which requires different kinds of dressing covers including hydrogels, hydrocolloids, alginates foams and films for treatment. The human amniotic membrane (hAM) is a biodegradable extracellular matrix with unique and tailorable physicochemical and biological properties, generated by the membrane itself or other cells that are located on the membrane surface. It is noted as a promising aid for wound healing and tissue regeneration due to the release of growth factors and cytokines, and its antibacterial and immunosuppressive properties. Moreover, hAM has optimal physical, biological, and mechanical properties, which makes it a much better option as a regenerative skin treatment than existing alternative materials. In addition, this layer has a structure with different layers and cells with different functions, which act as a regenerative geometry and reservoir of bioactive substances and cells for wound healing. In the present work, the structural and biological features of hAM are introduced as well as the application of this layer in different forms of composites to enhance wound healing. Future studies are recommended to detect possible further functionalization to enhance the hAM effectiveness on wound healing.

Retention processed placental membrane versus standard of care in treating diabetic foot ulcers

Diabetic foot ulcers (DFUs) are a severe complication for diabetic patients, significantly impacting patient quality of life and healthcare system efficiency. Traditional standard of care (SOC) treatments are inadequate for many patients, necessitating the use of advanced wound care products, such as human placental membranes. We studied a real-world population of large, hard-to-heal and complicated wounds, otherwise under-studied in the wound care literature. To this end, we conducted a retrospective cohort analysis to compare the effectiveness of a human placental amnion/chorion membrane product using retention-based processing (RE-AC) and SOC in managing chronic DFUs. During the study period of September 2021 through April 2024, we collected retrospective observational data from electronic health records of 21 patients treated with RE-AC at three outpatient wound care centres. Additionally, 21 control SOC patients were matched from a wound registry using Coarsened Exact Matching. Patients were categorized into two cohorts based on whether they received RE-AC or SOC. Key metrics included wound size progression and wound closure. The analysis employed Bayesian regression and Hurdle Gamma Analysis of Covariance models. Despite their rather large size (average of 13.8 cm2), our results indicated that RE-AC achieved almost a 10% higher expected wound closure rate compared to SOC at 12 weeks (8.53% [credible interval: 5.60%-10.7%]). Further, for wounds that did not close, RE-AC resulted in a 93.6% (credible interval: 147.7%-41.6) improvement in expected Percent Area Reduction over the SOC group at 12 weeks. We noted that on average, SOC wounds stalled or grew larger. In terms of a risk ratio comparing the study group with SOC, we found a 52% benefit in the RE-AC group (RR = 1.52). The findings suggest that even with larger DFUs, R-AC is superior to SOC for wound closure and expected Percent Area Reduction by 12 weeks. This benefit likely leads to reduced treatment costs, optimized resource utilization and improved outcomes in the DFU patient population; ultimately resulting in improved patient care.

Assessing placental membrane treatment efficiency in diabetic foot ulcers: Processing for retention versus lamination

Background

Diabetic foot ulcers are a severe complication in diabetic patients, significantly impact healthcare systems and patient quality of life, often leading to hospitalization and amputation. Traditional Standard of Care (SOC) treatments are inadequate for many patients, necessitating advanced wound care products (AWCPs) like human placental membranes. This study conducts a retrospective analysis to compare the effectiveness of two human placental membrane products, retention-processed amnion chorion (RE-AC) and lamination-processed amnion chorion (L-AC) in managing chronic diabetic foot ulcers (DFUs).

Methods

The study collected retrospective observational data from electronic health records (EHRs) of patients treated for DFU at three outpatient wound care centers. Patients were categorized into two cohorts based on the treatment received. Key metrics included wound size progression and the number of product applications. The analysis employed Bayesian estimation, utilizing an analysis of covariance model with a Hurdle Gamma likelihood.

Results

We found that RE-AC achieved a marginally higher expected Percent Area Reduction (xPAR) in DFUs compared to L-AC at 12 weeks (67.3% vs. 52.6%). RE-AC also required fewer applications, suggesting greater efficiency in general wound closure. Probability of full wound closure was similar in both groups (0.738 vs 0.740 in RE-AC and L-AC, respectively).

Conclusion

The findings suggest that while L-AC might be slightly more effective in complete ulcer healing, RE-AC offers overall better treatment efficiency, especially in reducing the frequency of applications. This efficiency can lead to improved patient comfort, reduced treatment costs, and optimized resource utilization in healthcare settings.

Retention of Key Characteristics of Unprocessed Chorion Tissue Resulting in a Robust Scaffold to Support Wound Healing

Placental membranes have been widely studied and used clinically for wound care applications, but there is limited published information on the benefits of using the chorion membrane. The chorion membrane represents a promising source of placental-derived tissue to support wound healing, with its native composition of extracellular matrix (ECM) proteins and key regulatory proteins. This study examined the impact of hypothermic storage on the structure of chorion membrane, ECM content, and response to degradation in vitro. Hypothermically stored chorion membrane (HSCM) was further characterized for its proteomic content, and for its functionality as a scaffold for cell attachment and proliferation in vitro. HSCM retained the native ECM structure, composition, and integrity of native unprocessed chorion membrane and showed no differences in response to degradation in an in vitro wound model. HSCM retained key regulatory proteins previously shown to be present in placental membranes and promoted the attachment and proliferation of fibroblasts in vitro. These data support the fact that hypothermic storage does not significantly impact the structure and characteristics of the chorion membrane compared to unprocessed tissue or its functionality as a scaffold to support tissue growth.

Mesenchymal Stem Cells and Regenerative Therapy with Bilateral Gracilis Flaps for Perineal Reconstruction of a Wound Infection in the Setting of Anal Squamous Cell Carcinoma

ABSTRACT

Many patients are affected by HIV/AIDS, and these conditions are highly prevalent worldwide. Patients with HIV/AIDS can experience debilitating wound infections that often require flap reconstruction and become challenging for surgeons to treat. In the past 5 years, mesenchymal stem cells have been tested and used as regenerative therapy to promote the growth of tissues throughout the body because of their ability to successfully promote cellular mitogenesis. To the authors' knowledge, the use of mesenchymal stem cell grafting following necrosis of a myocutaneous gracilis flap (as part of perineal wound reconstruction) has never been reported in the literature.In addition, the use of mesenchymal stem cells and regenerative medicine combined in the setting of squamous cell carcinoma of the anus with prior radiation (along with comorbid AIDS) has not been previously documented.In this report, the authors outline the case of a 60-year-old patient who had a recipient bed (perineum) complication from prior radiation therapy. Complicating the clinical picture, the patient also developed a Pseudomonal organ space infection of the pelvis leading to the failure of a vertical rectus abdominis myocutaneous flap and myocutaneous gracilis flaps. As a result, the patient underwent serial operative debridements for source control, with the application of mesenchymal stem cells, fetal bovine dermis, porcine urinary bladder xenograft, and other regenerative medicine products, achieving a highly successful clinical outcome. A procedural description for future use and replication of this method is provided.

Preparation of human amniotic membrane for transplantation in different application areas

The human amniotic membrane (hAM) is the inner layer of the placenta and plays protective and nutritional roles for the fetus during pregnancy. It contains multiple growth factors and proteins that mediate unique regenerative properties and enhance wound healing in tissue regeneration. Due to these characteristics hAM has been successfully utilized in ophthalmology for many decades. This material has also found application in a variety of additional therapeutic areas. Particularly noteworthy are the extraordinary effects in the healing of chronic wounds and in the treatment of burns. But hAM has also been used successfully in gynecology, oral medicine, and plastic surgery and as a scaffold for in vitro cell culture approaches. This review aims to summarize the different graft preparation, preservation and storage techniques that are used and to present advantages and disadvantages of these methods. It shows the characteristics of the hAM according to the processing and storage methods used. The paper provides an overview of the currently mainly used application areas and raises new application possibilities. In addition, further preparation types like extracts, homogenates, and the resulting treatment alternatives are described.

The Use of a Dehydrated Complete Human Placental Membrane Allograft for Mohs Surgical Defects of the Nose

BACKGROUND

Repair options for Mohs surgical defects include primary closure, flap or graft, or healing by second intention. These options may not be optimal in all cases. A dehydrated complete human placental membrane (dCHPM) allograft may serve as an alternative repair option.

OBJECTIVE

To assess the aesthetic and functional outcomes of an alternative repair technique for Mohs surgical defects of the nose.

METHODS

Twenty patients with Mohs surgical defects of the nose repaired with a dCHPM allograft were retrospectively identified. Photographs were used to demonstrate surgical technique and outcomes. Two blinded observers evaluated final outcomes using the Patient and Observer Scar Assessment Scale.

RESULTS

Observers rated the scar outcome a combined mean score of 8.4 ± 3.2 (scale 5-50). Patients rated their outcomes a mean of 12.6 ± 7.4 (scale 6-60). The mean "Overall Opinion score" was 2.5 ± 1.8 by patients and 1.9 ± 1.3 by observers (scale 1-10).

LIMITATIONS

This was a single institution study with a small sample size.

CONCLUSION

Our study demonstrates that dCHPM allografts are a viable alternative repair option for Mohs surgical defects of the nose.

Regenerative vs flap-based limb salvage: a multi-centered, prospective, randomized controlled trial

Aim: The goal of this study was to compare success rates of a regenerative limb salvage approach (rLS) using dehydrated human chorion amnion membrane (dHACM) to traditional flap-based limb salvage (fLS). Materials & methods: This prospective RTC enrolled patients presenting with complex extremity wounds over a 3-year period. Primary outcomes included success of primary reconstruction, persistence of exposed structures, time to definitive closure, and time to weight bearing. Results: Patients meeting inclusion criteria were randomized to fLS (n = 14) or rLS (n = 25). The primary reconstructive method was successful for 85.7% of fLS subjects and 80% of rLS subjects (p = 1.00). Conclusion: This trial provides strong evidence that rLS is an effective option in the setting of complex extremity wounds, with success rates comparable to traditional flaps. Clinical Trial Registration: NCT03521258 (ClinicalTrials.gov).

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.

Safety and efficacy of acellular human amniotic fluid and membrane in the treatment of non-healing wounds in a patient with chronic venous insufficiency

Chronic, non-healing venous ulcers of the lower extremity are often limb-threatening conditions. Their management is characterized by a prolonged and frequently frustrating clinical course that represents an economic burden to both the patient and healthcare system. During the last two decades, thermal ablation of underlying incompetent venous systems has been extensively utilized to treat chronic venous insufficiency. Despite successful correction of venous hypertension, a substantial subgroup of patients remain affected by non-healing venous ulcers, thus posing a significant clinical challenge. In this case report, we detail quantitative and qualitative wound treatment course in a patient refractory to standard interventions, by treatment with a combination of cell-free amniotic fluid and dehydrated amniotic membrane following successful thermal ablation of refluxing veins.

Reporting of Financial Conflicts of Interest in Studies of Placental Membrane Allografts

Objective: To systematically review the accuracy of self-reported financial conflicts of interest (COI) by authors of placental membrane allograft product studies. Approach: A PubMed search identified placental membrane allograft studies published between 2015 and 2019. Industry payments were collected using the Centers for Medicare & Medicaid Services Open Payments database. Self-declared COI were compared with recorded payments. Risk factors for positive product recommendation were determined at study and author levels. Results: Eighty-nine studies (417 authors) were identified. Seventy-five studies (84%) had at least one author receive undisclosed payments. From 2015 to 2019, 5,841 general payments (totaling $15,558,026) and 1,234 research payments (totaling $18,290,062) were made by 46 companies. Travel/lodging was the most commonly reported transaction (34%). Authors were comprised mostly of podiatrists (27%), plastic surgeons (15%), and orthopedic surgeons (15%). Comparative studies were less likely to have a positive product recommendation compared to noncomparative studies (odds ratio [OR] 0.204, 95% confidence interval 0.06-0.066, p = 0.02). Multivariate analysis showed no association between COI discrepancy and product recommendation. Innovation: The accuracy of self-reported financial COI in placental membrane studies is evaluated for the first time. Conclusion: The majority of placental membrane product studies did not declare all industry payments. Whether these payments represent "relevant COI" remains unclear. In addition, not all placental product companies report to the Open Payments database, suggesting that the issue may be even more significant. This study highlights the need for improved definitions of "relevant COI," a standardized reporting system across journals, and the uniform participation of all medical product vendors.

A comprehensive review on methods for promotion of mechanical features and biodegradation rate in amniotic membrane scaffolds

Amniotic membrane (AM) is a biological tissue that surrounds the fetus in the mother's womb. It has pluripotent cells, immune modulators, collagen, cytokines with anti-fibrotic and anti-inflammatory effect, matrix proteins, and growth factors. In spite of the biological characteristics, some results have been released in preventing the adhesion on traumatized surfaces. Application of the AM as a scaffold is limited due to its low biomechanical resistance and rapid biodegradation. Therefore, for using the AM during surgery, its modification by different methods such as cross-linking of the membrane collagen is necessary, because the cross-linking is an effective way to reduce the rate of biodegradation of the biological materials. In addition, their cross-linking is likely an efficient way to increase the tensile properties of the material, so that they can be easily handled or sutured. In this regard, various methods related to cross-linking of the AM subsuming the composite materials, physical cross-linking, and chemical cross-linking with the glutraldehyde, carbodiimide, genipin, aluminum sulfate, etc. are reviewed along with its advantages and disadvantages in the current work.

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.

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.

Human Amniotic Membrane: A review on tissue engineering, application, and storage

Human amniotic membrane (hAM) has been employed as scaffolding material in a wide range of tissue engineering applications, especially as a skin dressing and as a graft for corneal treatment, due to the structure of the extracellular matrix and excellent biological properties that enhance both wound healing and tissue regeneration. This review highlights recent work and current knowledge on the application of native hAM, and/or production of hAM-based tissue-engineered products to create scaffolds mimicking the structure of the native membrane to enhance the hAM performance. Moreover, an overview is presented on the available (cryo) preservation techniques for storage of native hAM and tissue-engineered products that are necessary to maintain biological functions such as angiogenesis, anti-inflammation, antifibrotic and antibacterial activity.

Regenerative Limb Salvage: A Novel Technique for Soft Tissue Reconstruction of Pediatric Extremities

Background In complex extremity wounds, free flap-based limb salvage (fLS) is the standard of care. However, fLS is resource- and cost-intensive, and the limited availability of pediatric microsurgical expertise exacerbates these challenges. Regenerative LS (rLS) addresses these barriers to care. The aim of this study was to quantify the efficacy, safety, and cost-effectiveness of rLS in complex pediatric extremity wounds.

Methods We conducted a retrospective cohort study of pediatric LS at a single hospital. Subjects were treated with fLS or rLS based on surgeon preference. Primary outcome measures were: definitive wound closure rates and time, rates of return to ambulation, number and length of procedures to achieve definitive closure, and rates of perioperative complications. Statistical analyses were performed utilizing the Wilcoxon Mann–Whitney U test with statistical significance set at p < 0.05.

Results Over a 2-year period, nine consecutive patients presented with complex extremity wounds requiring fLS (n = 4) or rLS (n = 5). Demographics and wound characteristics were similar between groups. Compared with fLS, the rLS group achieved definitive wound closure 85.8% more quickly (13.8 vs. 97.5 days, p < 0.02), required 64.5% less operative time (132.6 vs. 373.0 minutes, p < 0.02), had fewer perioperative complications (0 vs. 5), and required fewer intensive care unit stays (0 vs. 1.3 days).

Conclusion These data indicate that rLS is a safe and efficacious option in pediatric patients requiring soft tissue reconstruction for LS. Use of this novel technique can restore the reconstructive ladder, thereby expand patient access to pediatric LS while minimizing morbidity and reducing LS-related resource utilization.

Human amniotic membrane allograft, a novel treatment for chronic diabetic foot ulcers: A systematic review and meta-analysis of randomised controlled trials

To evaluate the efficacy and safety of human amniotic membrane (HAM) allograft in treating chronic diabetic foot ulcers (DFUs), a comprehensive search of randomised controlled trials in MEDLINE, EMBASE, PubMed, CENTRAL and Web of Science was conducted to December 7, 2019. Two reviewers independently screened the studies, extracted data, and evaluated the quality of studies. The primary outcome was the proportion of complete healing. The secondary outcomes were mean time to complete healing and adverse events. Statistical analyses were performed using RevMan 5.3. We identified 257 articles, of which 7 articles (465 participants) were included in the meta-analysis. The proportion of complete wound healing in HAM plus standard of care (SOC) group was 3.88 times as high as that in SOC alone (RR: 3.88 [95% CI: 2.34, 6.44]) at 6 weeks, and 2.01 times at 12 weeks (RR: 2.01 [95%CI: 1.45, 2.77]). The intervention group had a significantly shorter time to complete healing (MD: -30.33 days, [95% CI: -37.95, -22.72]). The number needed to treat within 6 weeks was 2.3 ([95% CI: 1.8, 3.1]). No significant difference was shown in adverse events. Results were consistent in a sensitivity analysis. Hence, HAM plus SOC is effective and safe in treating chronic DFUs.

FGF-2-Induced Human Amniotic Mesenchymal Stem Cells Seeded on a Human Acellular Amniotic Membrane Scaffold Accelerated Tendon-to-Bone Healing in a Rabbit Extra-Articular Model

Background

FGF-2 (basic fibroblast growth factor) has a positive effect on the proliferation and differentiation of many kinds of MSCs. Therefore, it represents an ideal molecule to facilitate tendon-to-bone healing. Nonetheless, no studies have investigated the application of FGF-2-induced human amniotic mesenchymal stem cells (hAMSCs) to accelerate tendon-to-bone healing in vivo.

Objective

The purpose of this study was to explore the effect of FGF-2 on chondrogenic differentiation of hAMSCs in vitro and the effect of FGF-2-induced hAMSCs combined with a human acellular amniotic membrane (HAAM) scaffold on tendon-to-bone healing in vivo.

Methods

In vitro, hAMSCs were transfected with a lentivirus carrying the FGF-2 gene, and the potential for chondrogenic differentiation of hAMSCs induced by the FGF-2 gene was assessed using immunofluorescence and toluidine blue (TB) staining. HAAM scaffold was prepared, and hematoxylin and eosin (HE) staining and scanning electron microscopy (SEM) were used to observe the microstructure of the HAAM scaffold. hAMSCs transfected with and without FGF-2 were seeded on the HAAM scaffold at a density of 3 × 10⁵ cells/well. Immunofluorescence staining of vimentin and phalloidin staining were used to confirm cell adherence and growth on the HAAM scaffold. In vivo, the rabbit extra-articular tendon-to-bone healing model was created using the right hind limb of 40 New Zealand White rabbits. Grafts mimicking tendon-to-bone interface (TBI) injury were created and subjected to treatment with the HAAM scaffold loaded with FGF-2-induced hAMSCs, HAAM scaffold loaded with hAMSCs only, HAAM scaffold, and no special treatment. Macroscopic observation, imageological analysis, histological assessment, and biomechanical analysis were conducted to evaluate tendon-to-bone healing after 3 months.

Results

In vitro, cartilage-specific marker staining was positive for the FGF-2 overexpression group. The HAAM scaffold displayed a netted structure and mass extracellular matrix structure. hAMSCs or hAMSCs transfected with FGF-2 survived on the HAAM scaffold and grew well. In vivo, the group treated with HAAM scaffold loaded with FGF-2-induced hAMSCs had the narrowest bone tunnel after three months as compared with other groups. In addition, macroscopic and histological scores were higher for this group than for the other groups, along with the best mechanical strength.

Conclusion

hAMSCs transfected with FGF-2 combined with the HAAM scaffold could accelerate tendon-to-bone healing in a rabbit extra-articular model.

On the Cutting Edge: Wound Care for the Endovascular Specialist

Clinical outcomes in patients with critical limb ischemia (CLI) depend not only on endovascular restoration of macrovascular blood flow but also on aggressive periprocedural wound care. Education about this area of CLI therapy is essential not only to maximize the benefits of endovascular therapy but also to facilitate participation in the multidisciplinary care crucial to attaining limb salvage. In this article, we review the advances in wound care products and therapies that have granted the wound care specialist the ability to heal previously nonhealing wounds. We provide a primer on the basic science behind wound healing and the pathogenesis of ischemic wounds, familiarize the reader with methods of tissue viability assessment, and provide an overview of wound debridement techniques, dressings, hyperbaric therapy, and tissue offloading devices. Lastly, we explore emerging technology on the horizons of wound care.

Biochemical characterization of pure dehydrated binate amniotic membrane: role of cytokines in the spotlight

AIM

Placental allografts used for tissue regeneration differ in membrane compositions and processing techniques. A uniquely folded dehydrated binate amniotic membrane (DBAM) was biochemically characterized to evaluate its potential role in wound healing.

METHODS

Histology, Luminex-based immunoassay and standard in vitro cell biology techniques were employed.

RESULTS

Histological staining confirmed that the DBAM was chorion free with epithelial cell layer of the respective amnion membranes facing outward. DBAM had quantifiable levels of relevant cytokines that induced proliferation and migration while bolstering secretory activity of the cells. DBAM retained biological efficacy at a broad range of temperatures.

CONCLUSION

Cytokines in DBAM stimulate bone marrow stromal and stem cells that may lead to tissue regeneration and wound healing in a clinical setup.

The Role of Placental Membrane Allografts in the Surgical Treatment of Tendinopathies

Placental membrane grafts have long been used in the realms of wound care and ophthalmology to assist in the healing cascade. Recently, surgeons have started to implant placental membrane grafts in a wide variety of foot and ankle surgeries to take advantage of their many touted benefits. The application of placental membrane grafts for cases of lower extremity tendinopathy is detailed in this article.

Effect of Lead on Human Middle Ear Epithelial Cells

Lead is a ubiquitous metal in the environment, but no studies have examined lead toxicity on the middle ear. Here, we investigated lead toxicity and its mechanism in human middle ear epithelial cells (HMEECs). Moreover, we investigated the protective effects of amniotic membrane extract (AME) and chorionic membrane extract (CME) against lead toxicity in HMEECs. Cell viability was analyzed using the cell counting kit, and reactive oxygen species (ROS) activity was measured using a cellular ROS detection kit. After lead(II) acetate trihydrate treatment, mRNA levels of various genes were assessed by semiquantitative real-time polymerase chain reaction. Following treatment with AME or CME after lead exposure, the changes in cell viability, ROS activity, and gene expression were analyzed. Exposure to >100 μg/mL of lead(II) acetate trihydrate caused a significant decrease in cell viability and increased ROS production in HMEECs. Lead exposure significantly increased the mRNA expression of genes encoding inflammatory cytokines and mucins. Administration of AME or CME restored cell viability, reduced ROS activity, and ameliorated mRNA levels. Our findings suggest that environmental lead exposure is related to the development of otitis media, and AME and CME may have antioxidative and anti-inflammatory effects against lead toxicity.

Biological effects of amniotic membrane on diabetic foot wounds: a systematic review

Objective:

The amniotic membrane has biological properties that are beneficial to the wound healing process of diabetic foot ulcers (DFU). Our aim is to analyse the scientific evidence found in literature on the use of the amniotic membrane to stimulate DFU healing.

Method:

A systematic review of amniotic membrane's influence was undertaken, using the search terms ‘placenta’ ‘diabetic foot’ ‘amnion’ and biological dressing’, assessing the outcomes ‘wound healing’ and ‘wound healing time’, in DFU. Following the inclusion and exclusion criteria, randomised controlled trials (RCT) were identified, and the risk of bias was analysed according to the Cochrane risk of bias tool. We conducted a meta-analysis of the two outcomes to evaluate the level of evidence.

Results:

We identified six clinical trials, with a total of 331 patients. The most common risks of bias in the studies were selection, attrition, and detection biases. From the meta-analysis, the difference of the intervention group (amnion) in relation to the control group was statistically significant. We found that wound healing in the group treated with amniotic membrane occurs 2.32 times more often and is 32 days faster in comparison with the group that used conventional dressings.

Conclusion:

There is statistical evidence to support the effectiveness of amniotic membrane in comparison with other conventional dressings. In addition, there is a clear tendency for the use of amniotic membrane treatment to result in a larger number of DFUs healing at a quicker rate.

Biological effects of amniotic membrane on diabetic foot wounds: a systematic review

OBJECTIVE

The amniotic membrane has biological properties that are beneficial to the wound healing process of diabetic foot ulcers (DFU). Our aim is to analyse the scientific evidence found in literature on the use of the amniotic membrane to stimulate DFU healing.

METHOD

A systematic review of amniotic membrane's influence was undertaken, using the search terms 'placenta' 'diabetic foot' 'amnion' and biological dressing', assessing the outcomes 'wound healing' and 'wound healing time', in DFU. Following the inclusion and exclusion criteria, randomised controlled trials (RCT) were identified, and the risk of bias was analysed according to the Cochrane risk of bias tool. We conducted a meta-analysis of the two outcomes to evaluate the level of evidence.

RESULTS

We identified six clinical trials, with a total of 331 patients. The most common risks of bias in the studies were selection, attrition, and detection biases. From the meta-analysis, the difference of the intervention group (amnion) in relation to the control group was statistically significant. We found that wound healing in the group treated with amniotic membrane occurs 2.32 times more often and is 32 days faster in comparison with the group that used conventional dressings.

CONCLUSION

There is no statistical evidence to support the effectiveness of amniotic membrane in comparison with other conventional dressings. However, there is a clear tendency for the use of amniotic membrane treatment to result in a larger number of DFUs healing at a quicker rate.

Current Techniques for Burn Reconstruction: Using Dehydrated Human Amnion/Chorion Membrane Allografts as an Adjunctive Treatment Along the Reconstructive Ladder

The reconstructive ladder is a term coined by reconstructive plastic surgeons to describe levels of increasingly complex management of wounds. The first rungs of the ladder is allowing the wound to heal by secondary intention, advancing up the ladder to direct tissue closure, with skin grafting and tissue transfer (flaps) comprising the higher rungs. Skin grafting and tissue transfer (flaps) at the middle and higher rungs of the ladder are often necessary for the treatment of complex burn injuries. Our purpose is to describe how dehydrated human amnion/chorion membrane allografts may be used as an adjunctive treatment.

Amniotic membrane application for the healing of chronic wounds and ulcers

Wound healing usually follows a predictable sequence and prognosis of events. Its evolutionary process is the result of a complicated interaction between patient-related factors, the wound, the treatment used and the skills and knowledge of the professionals who treat them. Only through a meticulous initial assessment of the wound is it possible to identify the factors that contribute to its complexity. The challenge for professionals will be to implement efficient therapies at the right time and in the most cost-efficient way in order to reduce associated problems, treat the symptoms and expectations of the patients and achieve adequate wound healing whenever possible. This is particularly evident in big chronic wounds with considerable tissue loss, which become senescent in the process of inflammation or proliferation losing the ability to epithelialize. Generally, chronic wounds do not respond to current treatments, therefore they need special interventions. AM is a tissue of particular interest as a biological dressing and it has well-documented reepithelialization effects which are in part related to its capacity to synthesize and release biological active factors. Our studies have demonstrated that amniotic membrane (AM) is able to induce epithelialization in chronic wounds that were unable to epithelialize. AM induces several signaling pathways that are involved in cell migration and/or proliferation. Additionally, AM is able to selectively antagonize the anti-proliferative effect of transforming growth factor-ß (TGF-β) by modifying the genetic program that TGF-β induces on keratinocytes. The combined effect of AM on keratinocytes, promoting cell proliferation/migration and antagonizing the effect of TGF-β is the perfect combination, allowing chronic wounds to move out of their non-healing state and progress into epithelialization.

Efficacy of freeze-dried amnion graft following hysteroscopic adhesiolysis of severe intrauterine adhesions

OBJECTIVE

To evaluate the efficacy of freeze-dried amnion graft for prevention of intrauterine adhesion (IUA) reformation after hysteroscopic adhesiolysis.

METHODS

A prospective randomized controlled trial was conducted among 88 women with severe IUAs who underwent hysteroscopic adhesiolysis at Beijing Obstetrics and Gynecology Hospital between July 15, 2015, and July 1, 2016. All participants had a balloon inserted into the uterine cavity for 1 week. Sterilized freeze-dried amnion graft covered the balloon portion of the Foley catheter among patients allocated to the amnion group (n=44), whereas patients in the control group (n=44) did not receive the graft. Follow-up hysteroscopy was performed 3 months after surgery. Preoperative and postoperative IUA scores, menstruation scores, and pregnancy rates were assessed.

RESULTS

Both groups exhibited reductions in IUA scores and improvements in menstruation scores following treatment (P<0.001 for each measure). Compared with the control group, the amnion group had a lower IUA score (P=0.032) and a higher menstruation score (P<0.001) at follow-up. By contrast, the rates of IUA reformation and pregnancy were not significantly different between the two groups.

CONCLUSION

Use of freeze-dried amnion graft was effective in reducing IUA reformation and improving menstruation (according to pictorial blood-loss assessment chart) following hysteroscopic adhesiolysis of severe IUAs. ClinicalTrials.gov: (NCT02496052).

Human Amniotic Membrane-Derived Products in Sports Medicine: Basic Science, Early Results, and Potential Clinical Applications

BACKGROUND

Amniotic membrane (AM)-derived products have been successfully used in ophthalmology, plastic surgery, and wound care, but little is known about their potential applications in orthopaedic sports medicine.

PURPOSE

To provide an updated review of the basic science and preclinical and clinical data supporting the use of AM-derived products and to review their current applications in sports medicine.

STUDY DESIGN

Systematic review.

METHODS

A systematic search of the literature was conducted using the Medline, EMBASE, and Cochrane databases. The search term amniotic membrane was used alone and in conjunction with stem cell, orthopaedic, tissue engineering, scaffold, and sports medicine.

RESULTS

The search identified 6870 articles, 80 of which, after screening of the titles and abstracts, were considered relevant to this study. Fifty-five articles described the anatomy, basic science, and nonorthopaedic applications of AM-derived products. Twenty-five articles described preclinical and clinical trials of AM-derived products for orthopaedic sports medicine. Because the level of evidence obtained from this search was not adequate for systematic review or meta-analysis, a current concepts review on the anatomy, physiology, and clinical uses of AM-derived products is presented.

CONCLUSION

Amniotic membranes have many promising applications in sports medicine. They are a source of pluripotent cells, highly organized collagen, antifibrotic and anti-inflammatory cytokines, immunomodulators, and matrix proteins. These properties may make it beneficial when applied as tissue engineering scaffolds, improving tissue organization in healing, and treatment of the arthritic joint. The current body of evidence in sports medicine is heavily biased toward in vitro and animal studies, with little to no human clinical data. Nonetheless, 14 companies or distributors offer commercial AM products. The preparation and formulation of these products alter their biological and mechanical properties, and a thorough understanding of these differences will help guide the use of AM-derived products in sports medicine research.

Hair Follicle Morphogenesis in the Treatment of Mouse Full-Thickness Skin Defects Using Composite Human Acellular Amniotic Membrane and Adipose Derived Mesenchymal Stem Cells

Early repair of skin injury and maximal restoration of the function and appearance have become important targets of clinical treatment. In the present study, we observed the healing process of skin defects in nude mice and structural characteristics of the new skin after transplantation of isolated and cultured adipose derived mesenchymal stem cells (ADMSCs) onto the human acellular amniotic membrane (AAM). The result showed that ADMSCs were closely attached to the surface of AAM and grew well 24 h after seeding. Comparison of the wound healing rate at days 7, 14, and 28 after transplantation showed that ADMSCs seeded on AAM facilitated the healing of full-thickness skin wounds more effectively as compared with either hAM or AAM alone, indicating that ADMSCs participated in skin regeneration. More importantly, we noticed a phenomenon of hair follicle development during the process of skin repair. Composite ADMSCs and AAM not only promoted the healing of the mouse full-thickness defects but also facilitated generation of the appendages of the affected skin, thus promoting restoration of the skin function. Our results provide a new possible therapy idea for the treatment of skin wounds with respect to both anatomical regeneration and functional restoration.

What's new in wound treatment: a critical appraisal

With the growing demand for the specialized care of wounds, there is an ever expanding abundance of wound care modalities available. It is difficult to identify which products or devices enhance wound healing, and thus, a critical and continual look at new advances is necessary. The goal of any wound regimen should be to optimize wound healing by combining basic wound care modalities including debridement, off-loading, and infection control with the addition of advanced therapies when necessary. This review takes a closer look at current uses of negative pressure wound therapy, bioengineered alternative tissues, and amniotic membrane products. While robust literature may be lacking, current wound care advances are showing great promise in wound healing.

Cryopreserved amniotic membrane as transplant allograft: viability and post-transplant outcome

Amniotic membrane (AM) transplantation is increasingly used in ophthalmological and dermatological surgeries to promote re-epithelialization and wound healing. Biologically active cells in the epithelial and stromal layers deliver growth factors and cytokines with anti-inflammatory, anti-bacterial, anti-immunogenic and anti-fibrotic properties. In this work, confocal microscopy was used to show that our cryopreservation protocol for AM yielded viable cells in both the stromal and epithelial layers with favorable post-transplant outcome. AM was obtained from Caesarean-section placenta, processed into allograft pieces of different sizes (3 cm × 3 cm, 5 cm × 5 cm, and 10 cm × 10 cm) and cryopreserved in 10 % dimethyl sulfoxide using non-linear controlled rate freezing. Post-thaw cell viability in the entire piece of AM and in the stromal and epithelial cell layers was assessed using a dual fluorescent nuclear dye and compared to hypothermically stored AM, while surveys from surgical end-users provided information on post-transplant patient outcomes. There was no significant statistical difference in the cell viability in the entire piece, epithelial and stromal layers regardless of the size of allograft piece (p = 0.092, 0.188 and 0.581, respectively), and in the entire piece and stromal layer of hypothermically stored versus cryopreserved AM (p = 0.054 and 0.646, respectively). Surgical end-user feedback (n = 49) indicated that 16.3 % of AM allografts were excellent and 61.2 % were satisfactory. These results support the expanded clinical use of different sizes of cryopreserved AM allografts and address the issue of orientation of the AM during transplant for the treatment of dermatological defects and ocular surface disorders.

Amniotic membrane is a potential regenerative option for chronic non-healing wounds: a report of five cases receiving dehydrated human amnion/chorion membrane allograft

A case series of five patients with a total of six chronic non-healing wounds (>30 day duration) were non-randomly selected to evaluate the performance, safety and handling properties of dehydrated human amnion/chorion membrane allograft, an amniotic membrane scaffolding product. The patients had lower extremity wounds that had previously failed standard of care within a university outpatient/inpatient wound healing programme. Five wounds treated with dehydrated amnion/chorion membrane allograft showed a mean 43% area reduction from baseline (51% median) at 3 weeks into treatment and completely healed with a 64-day median time to closure (SD ±27·6 days). One wound worsened at 3 weeks and was found to have a complete central vein obstruction that was treated with long-term mild compression but still eventually healed at 6 months. Removing this outlier, the four responding wounds had a 72% mean and 69% median change in area from baseline, at the 3 week point. All five patients received only one application of dehydrated human amnion/chorion membrane allograft, and there were no adverse events. The product was easy to use, administer and handle. In summary, dehydrated human amnion/chorion membrane allograft appears to be a safe, effective and easy to use therapy for chronic non-healing wounds. This study describes the details of these clinical cases and provides an overview of the current evidence on the use of amniotic tissue in clinical practice.