Similarities between induced membrane and amniotic membrane: Novelty for bone repair

A review of the Masquelet technique in the treatment of lower limb critical-size bone defects

The need for bone tissue to heal effectively is paramount given its role in the mechanical support of tissues. Bone has a very good natural healing potential in comparison with most other tissue types, largely regenerating to its pre-injury state in the vast majority of cases. Certain factors such as high energy trauma, tumour resection, revision surgery, developmental deformities and infection can lead to the formation of bone defects, where the intrinsic healing potential of bone is diminished owing to bone loss. Various approaches to resolving bone defects exist in current practice, each with their respective benefits and drawbacks. These include bone grafting, free tissue transfer, Ilizarov bone transport and the Masquelet induced membrane technique. This review focuses on evaluating the Masquelet technique, discussing its method and underlying mechanisms, the effectiveness of certain modifications, and its potential future directions.

Strategies of immobilizing BMP-2 with 3D-printed scaffolds to improve osteogenesis

The management and definitive treatment of critical-size bone defects in severe trauma, tumor resection and congenital malformation are troublesome for orthopedic surgeons and patients worldwide without recognized good treatment strategies. Researchers and clinicians are working to develop new strategies to treat these problems. This review aims to summarize the techniques used by additive manufacturing scaffolds loaded with BMP-2 to promote osteogenesis and to analyze the current status and trends in relevant clinical translation. Optimize composite scaffold design to enhance bone regeneration through printing technology, material selection, structure design and loading methods of BMP-2 to advance the clinical therapeutic bone repair field.

Time-varying characteristics of the induced membrane and its effects on bone defect repair

PURPOSE

This study intended to determine the properties of induced membranes after various periods of polymethyl methacrylate (PMMA) retention and the effect of different retention intervals on subsequent defect repair.

METHODS

Model of a critical bone defect in rabbits was prepared to obtain the induced membrane. For varying intervals of spacer insertion (2, 4, 6, 8, 12, 16, and 20 weeks postoperatively), angiogenesis, osteogenesis, and MSC-related properties were analyzed by immunohistochemistry and western-blot. Furthermore, 2, 4, 6, and 8 weeks after PMMA insertion, bone grafting was performed. Characteristics of defect repair were analyzed by X-ray and micro-CT analysis.

RESULTS

The induced membrane displayed angiogenesis, osteogenesis, and MSC-related properties from the 2- to 20-week intervals. Quantitation of protein expression (RUNX2, ALP, VEGF, TGF-beta, OCT4, and STRO1) revealed that selected proteins gradually rose to a high level at 4-8 weeks postoperatively and then decreased to a low level over a long time period. Following bone grafting, the most new bone formation was in the group when grafting was performed at 4 weeks, followed by the groups at 2 and 6 weeks, with the least in the group at 8 weeks.

CONCLUSION

The induced membrane displays angiogenesis, osteogenesis, and MSC-related properties from the 2- to 20-week intervals. These were increased to a peak level at 4-8 weeks postoperatively and then gradually decreased. The optimal timing for bone grafting at the second stage in the presented model was 4 weeks after PMMA insertion.

Reporting Criteria for Clinical Trials on Medication-Related Osteonecrosis of the Jaw (MRONJ): A Review and Recommendations

Medication-related osteonecrosis of the jaw (MRONJ) is a complication caused by anti-resorptive agents and anti-angiogenesis drugs. Since we wanted to write a protocol for a randomized clinical trial (RCT), we reviewed the literature for the essential information needed to estimate the size of the active patient population and measure the effects of therapeutics. At the same time, we designed a questionnaire intended for clinicians to collect detailed information about their practices. Twelve essential criteria and seven additional items were identified and compiled from 43 selected articles. Some of these criteria were incorporated in the questionnaire coupled with data on clinical practices. Our review found extensive missing data and a lack of consensus. For example, the success rate often combined MRONJ stages, diseases, and drug treatments. The occurrence date and evaluation methods were not harmonized or quantitative enough. The primary and secondary endpoints, failure definition, and date coupled to bone measurements were not well established. This information is critical for writing a RCT protocol. With this review article, we aim to encourage authors to contribute all their findings in the field to bridge the current knowledge gap and provide a stronger database for the coming years.

Influence of the Immune Microenvironment Provided by Implanted Biomaterials on the Biological Properties of Masquelet-Induced Membranes in Rats: Metakaolin as an Alternative Spacer

Macrophages play a key role in the inflammatory phase of wound repair and foreign body reactions-two important processes in the Masquelet-induced membrane technique for extremity reconstruction. The macrophage response depends largely on the nature of the biomaterials implanted. However, little is known about the influence of the macrophage microenvironment on the osteogenic properties of the induced membrane or subsequent bone regeneration. We used metakaolin, an immunogenic material, as an alternative spacer to standard polymethylmethacrylate (PMMA) in a Masquelet model in rats. Four weeks after implantation, the PMMA- and metakaolin-induced membranes were harvested, and their osteogenic properties and macrophage microenvironments were investigated by histology, immunohistochemistry, mass spectroscopy and gene expression analysis. The metakaolin spacer induced membranes with higher levels of two potent pro-osteogenic factors, transforming growth factor-β (TGF-β) and bone morphogenic protein-2 (BMP-2). These alternative membranes thus had greater osteogenic activity, which was accompanied by a significant expansion of the total macrophage population, including both the M1-like and M2-like subtypes. Microcomputed tomographic analysis showed that metakaolin-induced membranes supported bone regeneration more effectively than PMMA-induced membranes through better callus properties (+58%), although this difference was not significant. This study provides the first evidence of the influence of the immune microenvironment on the osteogenic properties of the induced membranes.

Human amniotic membrane application in oral surgery—An ex vivo pilot study

Objectives: The purpose of this pilot porcine study was to explore and illustrate the surgical application of human amniotic membrane (hAM) in an ex vivo model of medication-related osteonecrosis of the jaw (MRONJ).

Material and methods: Five oral and maxillofacial surgeons participated to this study. MRONJ was simulated on porcine mandible specimens. hAM was applied using four different techniques: implantation with complete coverage, implantation with partial coverage, apposition and covering graft material. At the same time, the surgeons evaluated how well the hAM handled and its physical properties during the surgery.

Results: Surgeons found that hAM had suitable mechanical properties, as it was easy to detach from the support, handle, bind to the defect and bury. hAM was also found to be strong and stable. The “implantation with complete coverage” and “implantation with partial coverage” techniques were the preferred choices for the MRONJ indication.

Conclusion: This study shows that hAM is a graft material with suitable properties for oral surgery. It is preferable to use it buried under the gingiva with sutures above it, which increases its stability. This technical note aims to educate surgeons and provide them with details about the handling of hAM in oral surgery.

Clinical relevance: Two surgical techniques for hAM application in MRONJ were identified and illustrated. hAM handling and physical properties during surgery were reported.

Questions about Residual Cell Viability in Cryopreserved Human Amniotic Membrane and Its Impact on Clinical Applications

We questioned the relevance of evaluating residual cell viability in human amniotic membrane (hAM) after its cryopreservation since cell survival is controversial and its ability to act as a matrix (including the presence of growth factors and cytokines) appears to be most important for tissue regeneration purposes. We also discussed the usefulness of osteodifferentiating amniotic cells in whole hAM for bone repair applications. We have evidence that determining residual cell viability after cryopreservation and hAM osteodifferentiation is not justified.

Masquelet technique in military practice: specificities and future directions for combat-related bone defect reconstruction

Because of its simplicity, reliability, and replicability, the Masquelet induced membrane technique (IMT) has become one of the preferred methods for critical bone defect reconstruction in extremities. Although it is now used worldwide, few studies have been published about IMT in military practice. Bone reconstruction is particularly challenging in this context of care due to extensive soft-tissue injury, early wound infection, and even delayed management in austere conditions. Based on our clinical expertise, recent research, and a literature analysis, this narrative review provides an overview of the IMT application to combat-related bone defects. It presents technical specificities and future developments aiming to optimize IMT outcomes, including for the management of massive multi-tissue defects or bone reconstruction performed in the field with limited resources.

Tips and Tricks and Clinical Outcome of Cryopreserved Human Amniotic Membrane Application for the Management of Medication-Related Osteonecrosis of the Jaw (MRONJ): A Pilot Study

Medication-related osteonecrosis of the jaw (MRONJ) is a complication of certain pharmacological treatments such as bisphosphonates, denosumab, and angiogenesis inhibitors. There are currently no guidelines on its management, particularly in advanced stages. The human amniotic membrane (hAM) has low immunogenicity and exerts anti-inflammatory, antifibrotic, antimicrobial, antiviral, and analgesic effects. It is a source of stem cells and growth factors promoting tissue regeneration. hAM acts as an anatomical barrier with suitable mechanical properties (permeability, stability, elasticity, flexibility, and resorbability) to prevent the proliferation of fibrous tissue and promote early neovascularization at the surgical site. In oral surgery, hAM stimulates healing and facilitates the proliferation and differentiation of epithelial cells in the oral mucosa and therefore its regeneration. We proposed using cryopreserved hAM to eight patients suffering from cancer (11 lesions) with stage 2–3 MRONJ on a compassionate use basis. A collagen sponge was added in some cases to facilitate hAM grafting. One or three hAMs were applied and one patient had a reapplication. Three patients had complete closure of the surgical site with proper epithelialization at 2 weeks, and two of them maintained it until the last follow-up. At 1 week after surgery, three patients had partial wound dehiscence with partial healing 3 months later and two patients had complete wound dehiscence. hAM reapplication led to complete healing. All patients remained asymptomatic with excellent immediate significant pain relief, no infections, and a truly positive impact on the patients’ quality of life. No adverse events occurred. At 6 months of follow-up, 80% of lesions had complete or partial wound healing (30 and 50%, respectively), while 62.5% of patients were in stage 3. Radiological evaluations found that 85.7% of patients had stable bone lesions (n = 5) or new bone formation (n = 1). One patient had a worsening MRONJ but remained asymptomatic. One patient did not attend his follow-up radiological examination. For the first time, this prospective pilot study extensively illustrates both the handling and surgical application of hAM in MRONJ, its possible association with a collagen sponge scaffold, its outcome at the site, the application of multiple hAM patches at the same time, and its reapplication.

Bone defect treatment: does the type and properties of the spacer affect the induction of Masquelet membrane? Evidence today

PURPOSE

High clinical success rates have been reported with the Masquelet technique in the treatment of traumatic bone loss. An increasing number of studies suggest that various factors can influence the properties of induced membranes. Goal of this systematic review is to answer the following questions: (1) which are the ideal spacer properties (material, surface topography, antibiotic supplementation) to booster the quality and osteogenic potential of induced membranes? (2) what is the ideal time to perform the second-stage operation?

METHODS

A systematic search using the keywords "((Masquelet) OR (Induced Periosteum)) AND ((Spacer) OR (Time))" was performed in PubMed, Embase and Cochrane Library according to PRISMA guidelines. Studies published up to the 23rd of February 2022 were included and assessed independently by two reviewers.

RESULTS

Thirteen animal and 1 clinical studies were identified to address the above questions. Spacer materials used were PMMA, silicone, titanium, polypropylene, PVA, PCL and calcium sulfate. With the exception of PVA sponges, all solid materials could induce membranes. Low union rates have been reported with titanium and rough surfaced spacers. Scraping of the inner surface of the IM also increased bony union rates. In terms of the ideal timing to perform the second-stage evidence suggests that membranes older than 8 weeks continue to have regenerative capacities similar to younger ones.

CONCLUSION

Membranes induced by smooth PMMA spacers loaded with low concentrations of antibiotics showed powerful osteogenic properties. Other materials such as Polypropylene or Calcium sulfate can also be used with good results. Despite current recommendation to perform the second stage operation in 4-8 weeks, membranes older than 8 weeks seem to have similar regenerative capacities to younger ones.

Immunohistochemical analysis revealed the expression of bone morphogenetic proteins-4, 6, 7, and 9 in human induced membrane samples treated with the Masquelet technique

Background

Induced membrane (IM) is the key component of Masquelet reconstruction surgery for the treatment of bone defects. IM is formed around the cement spacer and is known to secrete growth factors and osteoinductive factors. However, there is limited evidence available concerning the presence of osteoinductive factors in IM. This study aimed to investigate the existence of bone morphogenetic proteins (BMPs) in IM harvested from patients during the treatment of bone defects using the Masquelet technique.

Methods

This study involved six patients whose bone defects had been treated using the Masquelet technique. The affected sites were the femur (n = 3) and the tibia (n = 3). During the second-stage surgery, 1 cm² pieces of IM were harvested. Histological sections of IM were immunostained with anti-BMP-4, 6, 7, and 9 antibodies. Human bone tissue served as the positive control.

Results

The presence of BMP-4, 6, 7, and 9 was observed in all IM samples. Further, immunolocalization of BMP-4, 6, 7, and 9 was observed in blood vessels and fibroblasts in all IM samples. Immunolocalization of BMP-4, 6, 7, and 9 was also observed in bone tissue within the IM in one sample, in which osteogenesis inside the IM was observed.

Conclusions

This study showed that osteoinductive factors BMP-4, 6, 7, and 9 were present in the IM harvested from patients, providing evidence indicating that the Masquelet technique effectively contributes to healing large bone defects. Therefore, it may be possible for surgeons to omit the addition of BMPs to bone grafts, given the endogenous secretion of BMPs from the IM.

Chorion and amnion/chorion membranes in oral and periodontal surgery: A systematic review

The aim of this study was to perform a systematic review on the clinical applications where chorion membrane (CM) and amnion/chorion membrane (ACM) were used for oral tissue regeneration procedures. Selection of articles was carried out by two evaluators in Pubmed and Scopus databases, and Outcomes (PICO) method was used to select the relevant articles. Clinical studies reporting the use of CM or ACM for oral soft and hard tissue regeneration were included. The research involved 21 studies conducted on 375 human patients. Seven clinical applications of CM and ACM in oral and periodontal surgery were identified: gingival recession treatment, intrabony and furcation defect treatment, alveolar ridge preservation, keratinized gum width augmentation around dental implants, maxillary sinus membrane repair, and large bone defect reconstruction. CM and ACM were compared to negative controls (conventional surgeries without membrane) or to the following materials: collagen membranes, dense polytetrafluoroethylene membranes, platelet-rich fibrin membranes, amnion membranes, and to a bone substitute. Several studies support the use of CM and ACM as an efficient alternative to current techniques for periodontal and oral soft tissue regeneration procedures. However, further studies are necessary to increase the level of evidence and especially to demonstrate their role for bone regeneration.

Surgical Application of Human Amniotic Membrane and Amnion-Chorion Membrane in the Oral Cavity and Efficacy Evaluation: Corollary With Ophthalmological and Wound Healing Experiences

Due to its intrinsic properties, there has been growing interest in human amniotic membrane (hAM) in recent years particularly for the treatment of ocular surface disorders and for wound healing. Herein, we investigate the potential use of hAM and amnion-chorion membrane (ACM) in oral surgery. Based on our analysis of the literature, it appears that their applications are very poorly defined. There are two options: implantation or use as a cover material graft. The oral cavity is submitted to various mechanical and biological stimulations that impair membrane stability and maintenance. Thus, some devices have been combined with the graft to secure its positioning and protect it in this location. This current opinion paper addresses in detail suitable procedures for hAM and ACM utilization in soft and hard tissue reconstruction in the oral cavity. We address their implantation and/or use as a covering, storage format, application side, size and number, multilayer use or folding, suture or use of additional protective covers, re-application and resorption/fate. We gathered evidence on pre- and post-surgical care and evaluation tools. Finally, we integrated ophthalmological and wound healing practices into the collected information. This review aims to help practitioners and researchers better understand the application of hAM and ACM in the oral cavity, a place less easily accessible than ocular or cutaneous surfaces. Additionally, it could be a useful reference in the generation of new ideas for the development of innovative protective covering, suturing or handling devices in this specific indication. Finally, this overview could be considered as a position paper to guide investigators to fulfill all the identified criteria in the future.

Applications of Human Amniotic Membrane for Tissue Engineering

An important component of tissue engineering (TE) is the supporting matrix upon which cells and tissues grow, also known as the scaffold. Scaffolds must easily integrate with host tissue and provide an excellent environment for cell growth and differentiation. Human amniotic membrane (hAM) is considered as a surgical waste without ethical issue, so it is a highly abundant, cost-effective, and readily available biomaterial. It has biocompatibility, low immunogenicity, adequate mechanical properties (permeability, stability, elasticity, flexibility, resorbability), and good cell adhesion. It exerts anti-inflammatory, antifibrotic, and antimutagenic properties and pain-relieving effects. It is also a source of growth factors, cytokines, and hAM cells with stem cell properties. This important source for scaffolding material has been widely studied and used in various areas of tissue repair: corneal repair, chronic wound treatment, genital reconstruction, tendon repair, microvascular reconstruction, nerve repair, and intraoral reconstruction. Depending on the targeted application, hAM has been used as a simple scaffold or seeded with various types of cells that are able to grow and differentiate. Thus, this natural biomaterial offers a wide range of applications in TE applications. Here, we review hAM properties as a biocompatible and degradable scaffold. Its use strategies (i.e., alone or combined with cells, cell seeding) and its degradation rate are also presented.

Histological analysis of induced membranes in patients whose bone defects were treated with the Masquelet technique to identify factors affecting the vascularity of induced membranes

Background

Rich vascularity of the induced membrane (IM) is important for Masquelet reconstruction surgery. The factors affecting IM vascularity are not completely understood. This study aimed to investigate these factors using histological samples of human IMs.

Methods

We retrospectively evaluated 36 patients whose bone defects were treated using the Masquelet technique. Two clinical pathologists analyzed histological sections of IM pieces (1 cm²). The number of blood vessels per 1 mm² was counted and compared among men and women, femur or tibia, with and without free flap surgery, antibiotic impregnation to the cement, osteogenesis inside the membrane, smoking, and diabetes mellitus. The number of blood vessels within the same patient was compared among different time points. Correlation analysis was performed among blood vessel numbers and patient age, duration of cement spacer placement, and histological grading scales (inflammation, foreign body reaction, and fibrosis).

Results

IM formation with rich vascularity and some inflammation, foreign body reaction, and fibrosis were histologically confirmed in all patients. We found 37.4 ± 19.1 blood vessels per 1 mm². The number of blood vessels was significantly lower in patients with than in those without free flap surgery; it was higher in patients with osteogenesis inside the IM. No significant correlations were found in any of the analyses.

Conclusion

Sex, patient age, smoking, diabetes mellitus, femur or tibia, duration of cement spacer placement, and antibiotic impregnation to the cement did not affect IM vascularization. IM vascularization was reduced in patients with than in those without free flap surgery.

Comparison of amniotic membrane versus the induced membrane for bone regeneration in long bone segmental defects using calcium phosphate cement loaded with BMP-2

Thanks to its biological properties, the human amniotic membrane (HAM) combined with a bone substitute could be a single-step surgical alternative to the two-step Masquelet induced membrane (IM) technique for regeneration of critical bone defects. However, no study has directly compared these two membranes. We first designed a 3D-printed scaffold using calcium phosphate cement (CPC). We assessed its suitability in vitro to support human bone marrow mesenchymal stromal cells (hBMSCs) attachment and osteodifferentiation. We then performed a rat femoral critical size defect to compare the two-step IM technique with a single-step approach using the HAM. Five conditions were compared. Group 1 was left empty. Group 2 received the CPC scaffold loaded with rh-BMP2 (CPC/BMP2). Group 3 and 4 received the CPC/BMP2 scaffold covered with lyophilized or decellularized/lyophilized HAM. Group 5 underwent a two- step induced membrane procedure with insertion of a polymethylmethacrylate (PMMA) spacer followed by, after 4 weeks, its replacement with the CPC/BMP2 scaffold wrapped in the IM. Micro-CT and histomorphometric analysis were performed after six weeks. Results showed that the CPC scaffold supported the proliferation and osteodifferentiation of hBMSCs in vitro. In vivo, the CPC/BMP2 scaffold very efficiently induced bone formation and led to satisfactory healing of the femoral defect, in a single-step, without autograft or the need for any membrane covering. In this study, there was no difference between the two-step induced membrane procedure and a single step approach. However, the results indicated that none of the tested membranes further enhanced bone healing compared to the CPC/BMP2 group.

Use of Amniotic Membrane and Its Derived Products for Bone Regeneration: A Systematic Review

Thanks to their biological properties, amniotic membrane (AM), and its derivatives are considered as an attractive reservoir of stem cells and biological scaffolds for bone regenerative medicine. The objective of this systematic review was to assess the benefit of using AM and amniotic membrane-derived products for bone regeneration. An electronic search of the MEDLINE-Pubmed database and the Scopus database was carried out and the selection of articles was performed following PRISMA guidelines. This systematic review included 42 articles taking into consideration the studies in which AM, amniotic-derived epithelial cells (AECs), and amniotic mesenchymal stromal cells (AMSCs) show promising results for bone regeneration in animal models. Moreover, this review also presents some commercialized products derived from AM and discusses their application modalities. Finally, AM therapeutic benefit is highlighted in the reported clinical studies. This study is the first one to systematically review the therapeutic benefits of AM and amniotic membrane-derived products for bone defect healing. The AM is a promising alternative to the commercially available membranes used for guided bone regeneration. Additionally, AECs and AMSCs associated with an appropriate scaffold may also be ideal candidates for tissue engineering strategies applied to bone healing. Here, we summarized these findings and highlighted the relevance of these different products for bone regeneration.

Induced-membrane treatment of refractory humeral non-union with or without bone defect

INTRODUCTION

Treatment of humeral non-union with or without bone defect is complex, with non-negligible rates of complication and failure. Few reports focused on management of treatment failure.

OBJECTIVE

The study hypothesis was that the induced-membrane technique associated in a 2-stage strategy to internal fixation provides systematic bone healing in refractory humeral non-union.

MATERIAL AND METHODS

The study included 15 patients, with a median age of 46.6 years, with humeral non-union of a mean 24 months' progression and mean history of 3 attempted revision surgeries. Seven patients showed bone defect, exceeding 5cm in 2 cases. Six had history of radial palsy.

RESULTS

Consolidation was achieved in all cases, at a mean 4.6 months. Ten patients underwent radial nerve transposition, 6 of whom had shown radial motor nerve palsy; all recovered within 2 to 5 months. There was 1 case of superficial infection, and 1 of seroma.

DISCUSSION

The induced-membrane technique ensures bone healing due to the biological properties of the membrane; the main drawback is the need for 2-stage surgery. When bone defect exceeds 5cm, a multi-perforated fibula segment can be placed inside the membrane to increase primary stability and enhance bone integration.

CONCLUSION

The induced-membrane technique is suited to humeral non-union, with or without bone defect. The 2-stage strategy is mandatory in case of suspected latent infection. In the 2-stage procedure, anteromedial radial nerve transposition facilitates the bone-graft stage.

LEVEL OF EVIDENCE

IV, retrospective study.

The Masquelet technique: Current concepts, animal models, and perspectives

Bone reconstruction within a critical-sized defect remains a real challenge in orthopedic surgery. The Masquelet technique is an innovative, two-step therapeutic approach for bone reconstruction in which the placement of a poly (methylmethacrylate) spacer into the bone defect induces the neo-formation of a tissue called "induced membrane." This surgical technique has many advantages and is often preferred to a vascularized bone flap or Ilizarov's technique. Although the Masquelet technique has achieved high clinical success rates since its development by Alain-Charles Masquelet in the early 2000s, very little is known about how the process works, and few animal models of membrane induction have been developed. Our successful use of this technique in the clinic and our interest in the mechanisms of tissue regeneration (notably bone regeneration) prompted us to develop a surgical model of the Masquelet technique in rats. Here, we provide a comprehensive review of the literature on animal models of membrane induction, encompassing the defect site, the surgical procedure, and the histologic and osteogenic properties of the induced membrane. We also discuss the advantages and disadvantages of those models to facilitate efforts in characterizing the complex biological mechanisms that underlie membrane induction.

Introduction of a New Surgical Method to Improve Bone Healing in a Large Bone Defect by Replacement of the Induced Membrane by a Human Decellularized Dermis Repopulated with Bone Marrow Mononuclear Cells in Rat

The Masquelet technique for the treatment of large bone defects is a two-stage procedure based on an induced membrane. We eliminate the first surgical step by using a decellularized dermal skin graft (Epiflex^®) populated with bone marrow mononuclear cells (BMC), as a replacement for the induced membrane. The aim of this study was to demonstrate the feasibility of this technology and provide evidence of equivalent bone healing in comparison to the induced membrane-technique. Therefore, 112 male Sprague–Dawley rats were allocated in six groups and received a 10 mm femoral defect. Defects were treated with either the induced membrane or decellularized dermis, with or without the addition of BMC. Defects were then filled with a scaffold (β-TCP), with or without BMC. After a healing time of eight weeks, femurs were taken for histological, radiological and biomechanical analysis. Defects treated with Epiflex^® showed increased mineralization and bone formation predominantly in the transplanted dermis surrounding the defect. No significant decrease of biomechanical properties was found. Vascularization of the defect could be enhanced by addition of BMC. Considering the dramatic reduction of a patient’s burden by the reduced surgical stress and shortened time of treatment, this technique could have a great impact on clinical practice.

The effects of human amniotic membrane on silicone related capsule formation in rats

Silicone breast implants are commonly used materials in plastic surgery for breast augmentation and reconstruction and the most severe complication of silicone implants are capsule contraction which occurs in 40% of patients. The aim of our study is to evaluate how the amniotic membrane alters the capsule formation effects of silicone 24 wistar rats were used in the study. We placed a bare silicone block into the left side (Subgroup A) and single layer amniotic membrane coated silicone block into the right side (Subgroup B) of the rats back. The rats were then separated into three groups and in group 1 rats were euthanized after 3 weeks, in group 2 after 12 weeks and in group 3 after 24 weeks. Then capsule thickness, fibroblast and lymphocyte cell counts were evaluated for each sample. In Group 2 and group 3, the capsule thickness in Subgroup B was detected to be statistically significantly lower than that in Subgroup A. In Group 1, 2, and 3, the lymphocyte count in the capsule tissue taken from Subgroup B was lower than Subgroup A but the difference was not statistically significant. In Group 2 and 3, the fibrocyte count detected in the capsule tissue in Subgroup B was found to be statistically significantly lower than Subgroup A. the amniotic membrane was demonstrated to reduce capsule thickness by the antifibrinolytic effect in our study.

In vitro osteodifferentiation of intact human amniotic membrane is not beneficial in the context of bone repair

The human amniotic membrane (hAM) is an attractive biomaterial for regenerative medicine, as it contains amniotic mesenchymal stromal cells (hAMSC), epithelial cells (hAEC) and growth factors. We examined the potential use of hAM in orthopaedic and maxillofacial bone surgery, integrating the requirements of current regulations regarding advanced therapy medicinal products (ATMP) in the European Union. Previous studies have described the potential osteodifferentiation of intact hAM during whole-tissue culture in osteogenic conditions. The present study aims to determine whether in vitro osteodifferentiation of hAM is needed in the context bone repair, and the influence of this process on tissue structure, cell phenotype and cell function. Different conditions (fresh or cultured hAM; intact or hAM-derived cells) were tested. Phenotypic and functional analyses were performed with standard approaches (cell culture and staining, histological and immunolabelling) as well as original approaches (tissue staining, energy dispersive X-ray and X-ray diffraction). In our study, non-osteodifferentiated hAM (i.e., fresh or native hAM) exhibited innate pre-osteoblastic potential. Osteodifferentiation of fresh hAM induced a change in tissue structure, cell phenotype and function. Therefore, we hypothesize that pre-osteodifferentiation may not be necessary, especially if it induces unwanted changes. To our surprise, in these osteogenic conditions, hAEC had a mesenchymal phenotype with osteocyte function, and even native synthesis of hydroxyapatite, focusing osteogenic potential mainly in this epithelial layer. In conclusion, in vitro osteodifferentiation by tissue culture does not appear to be necessary for hAM to be used as an innovative ATMP for bone repair.

Can the amniotic membrane be used to treat peripheral nerve defects? A review of literature

Human amniotic membrane is currently being used in ophthalmology and dermatology applications. The objective of this review was to establish proof-of-concept for using amniotic membrane to treat peripheral nerve defects. We performed a search using: 1) PubMed with the keywords/MeSH terms: "amnion", "amniotic membrane", "angiogenesis", "anti-microbial", "characteristic", "chorion", "epithelialization", "fibrosis", "gap", "growth factors", "use", "nerve"; 2) the American clinical trials registry with "amniotic membrane"; 3) Lim Jeremy's book "A primer on amniotic membrane regenerative healing"; 4) the search engine Google. Our findings pointed to the amniotic membrane being a biodegradable and bioactive scaffold that contains many growth factors important for efficient nerve regeneration. Multiple animal studies and the single human clinical trial performed up to now have highlighted its role in preventing recurrence of perineural adhesions, reducing fibrosis, accelerating nerve repair and improving nerve function. Thus, the amniotic membrane has ideal properties for treating peripheral nerve injuries. It could very likely prevent neuroma formation. The best format would be a freeze-dried one containing the amnion and chorion layers in order to preserve all its growth factors, and facilitate its handling and storage in the operating room.

Human amniotic membrane for guided bone regeneration of calvarial defects in mice

Due to its biological properties, human amniotic membrane (hAM) is widely studied in the field of tissue engineering and regenerative medicine. hAM is already very attractive for wound healing and it may be helpful as a support for bone regeneration. However, few studies assessed its potential for guided bone regeneration (GBR). The purpose of the present study was to assess the potential of the hAM as a membrane for GBR. In vitro, cell viability in fresh and cryopreserved hAM was assessed. In vivo, we evaluated the impact of fresh versus cryopreserved hAM, using both the epithelial or the mesenchymal layer facing the defect, on bone regeneration in a critical calvarial bone defect in mice. Then, the efficacy of cryopreserved hAM associated with a bone substitute was compared to a collagen membrane currently used for GBR. In vitro, no statistical difference was observed between the conditions concerning cell viability. Without graft material, cryopreserved hAM induced more bone formation when the mesenchymal layer covered the defect compared to the defect left empty. When associated with a bone substitute, such improved bone repair was not observed. These preliminary results suggest that cryopreserved hAM has a limited potential for GBR.