Potential use of the human amniotic membrane as a scaffold in human articular cartilage repair

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

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

A Systematic Review of Human Amnion Enhanced Cartilage Regeneration in Full-Thickness Cartilage Defects

Cartilage defects present a significant challenge in orthopedic medicine, often leading to pain and functional impairment. To address this, human amnion, a naturally derived biomaterial, has gained attention for its potential in enhancing cartilage regeneration. This systematic review aims to evaluate the efficacy of human amnion in enhancing cartilage regeneration for full-thickness cartilage defects. An electronic search was conducted on MEDLINE-PubMed, Web of Science (WoS), and the Scopus database up to 27 December 2023 from 2007. A total of 401 articles were identified. After removing 125 duplicates and excluding 271 articles based on predetermined criteria, only 5 articles remained eligible for inclusion in this systematic review. All five eligible articles conducted in vivo studies utilizing rabbits as subjects. Furthermore, analysis of the literature reveals an increasing trend in the frequency of utilizing human amnion for the treatment of cartilage defects. Various forms of human amnion were utilized either alone or seeded with cells prior to implantation. Histological assessments and macroscopic observations indicated usage of human amnion improved cartilage repair outcomes. All studies highlighted the positive results despite using different forms of amnion tissues. This systematic review underscores the promising role of human amnion as a viable option for enhancing cartilage regeneration in full-thickness cartilage defects, thus offering valuable insights for future research and clinical applications in orthopedic tissue engineering.

Stem-Cell-Driven Chondrogenesis: Perspectives on Amnion-Derived Cells

Regenerative medicine harnesses stem cells' capacity to restore damaged tissues and organs. In vitro methods employing specific bioactive molecules, such as growth factors, bio-inductive scaffolds, 3D cultures, co-cultures, and mechanical stimuli, steer stem cells toward the desired differentiation pathways, mimicking their natural development. Chondrogenesis presents a challenge for regenerative medicine. This intricate process involves precise modulation of chondro-related transcription factors and pathways, critical for generating cartilage. Cartilage damage disrupts this process, impeding proper tissue healing due to its unique mechanical and anatomical characteristics. Consequently, the resultant tissue often forms fibrocartilage, which lacks adequate mechanical properties, posing a significant hurdle for effective regeneration. This review comprehensively explores studies showcasing the potential of amniotic mesenchymal stem cells (AMSCs) and amniotic epithelial cells (AECs) in chondrogenic differentiation. These cells exhibit innate characteristics that position them as promising candidates for regenerative medicine. Their capacity to differentiate toward chondrocytes offers a pathway for developing effective regenerative protocols. Understanding and leveraging the innate properties of AMSCs and AECs hold promise in addressing the challenges associated with cartilage repair, potentially offering superior outcomes in tissue regeneration.

Epicardial placement of human placental membrane protects from heart injury in a swine model of myocardial infarction

Cardiac ischemic reperfusion injury (IRI) is paradoxically instigated by reestablishing blood-flow to ischemic myocardium typically from a myocardial infarction (MI). Although revascularization following MI remains the standard of care, effective strategies remain limited to prevent or attenuate IRI. We hypothesized that epicardial placement of human placental amnion/chorion (HPAC) grafts will protect against IRI. Using a clinically relevant model of IRI, swine were subjected to 45 min percutaneous ischemia followed with (MI + HPAC, n = 3) or without (MI only, n = 3) HPAC. Cardiac function was assessed by echocardiography, and regional punch biopsies were collected 14 days post-operatively. A deep phenotyping approach was implemented by using histological interrogation and incorporating global proteomics and transcriptomics in nonischemic, ischemic, and border zone biopsies. Our results established HPAC limited the extent of cardiac injury by 50% (11.0 ± 2.0% vs. 22.0 ± 3.0%, p = 0.039) and preserved ejection fraction in HPAC-treated swine (46.8 ± 2.7% vs. 35.8 ± 4.5%, p = 0.014). We present comprehensive transcriptome and proteome profiles of infarct (IZ), border (BZ), and remote (RZ) zone punch biopsies from swine myocardium during the proliferative cardiac repair phase 14 days post-MI. Both HPAC-treated and untreated tissues showed regional dynamic responses, whereas only HPAC-treated IZ revealed active immune and extracellular matrix remodeling. Decreased endoplasmic reticulum (ER)-dependent protein secretion and increased antiapoptotic and anti-inflammatory responses were measured in HPAC-treated biopsies. We provide quantitative evidence HPAC reduced cardiac injury from MI in a preclinical swine model, establishing a potential new therapeutic strategy for IRI. Minimizing the impact of MI remains a central clinical challenge. We present a new strategy to attenuate post-MI cardiac injury using HPAC in a swine model of IRI. Placement of HPAC membrane on the heart following MI minimizes ischemic damage, preserves cardiac function, and promotes anti-inflammatory signaling pathways.

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.

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.

Injectable amnion hydrogel-mediated delivery of adipose-derived stem cells for osteoarthritis treatment

Current treatment strategies for osteoarthritis (OA) predominantly address symptoms with limited disease-modifying potential. There is a growing interest in the use of adipose-derived stem cells (ADSCs) for OA treatment and developing biomimetic injectable hydrogels as cell delivery systems. Biomimetic injectable hydrogels can simulate the native tissue microenvironment by providing appropriate biological and chemical cues for tissue regeneration. A biomimetic injectable hydrogel using amnion membrane (AM) was developed which can self-assemble in situ and retain the stem cells at the target site. In the present study, we evaluated the efficacy of intraarticular injections of AM hydrogels with and without ADSCs in reducing inflammation and cartilage degeneration in a collagenase-induced OA rat model. A week after the induction of OA, rats were treated with control (phosphate-buffered saline), ADSCs, AM gel, and AM-ADSCs. Inflammation and cartilage regeneration was evaluated by joint swelling, analysis of serum by cytokine profiling and Raman spectroscopy, gross appearance, and histology. Both AM and ADSC possess antiinflammatory and chondroprotective properties to target the sites of inflammation in an osteoarthritic joint, thereby reducing the inflammation-mediated damage to the articular cartilage. The present study demonstrated the potential of AM hydrogel to foster cartilage tissue regeneration, a comparable regenerative effect of AM hydrogel and ADSCs, and the synergistic antiinflammatory and chondroprotective effects of AM and ADSC to regenerate cartilage tissue in a rat OA model.

Hypothermically Stored Amniotic Membrane for the Treatment of Cartilage Lesions: A Single-Arm Prospective Study with 2-Year Follow-Up

OBJECTIVE

The purpose of this study was to determine the safety and efficacy of hypothermically stored amniotic membrane (HSAM) for the treatment of cartilage lesions of the knee using imaging, patient-reported outcomes (PROs), second-look arthroscopy, and histology. Patients were treated with HSAM and followed for 2 years.

DESIGN

Subjects with focal chondral lesions of the femur (International Cartilage Repair Society grade 3-4) were enrolled in this single-arm prospective study. Standard of care imaging was completed. PROs, including the Knee Injury and Osteoarthritis Outcome Score (KOOS), Marx Activity Scale, and Visual Analog Scale (VAS), were collected at baseline and at 3, 6, 12, 18, and 24 months. Three subjects underwent an optional arthroscopy and biopsy of the repair at 24 months.

RESULTS

Ten subjects were enrolled and completed the study. At 24 months, KOOS Sports & Recreation improved 173.3% and Quality of Life improved 195.3% from baseline. Marx Activity Scale increased 266.8% from 12 to 24 months. VAS scores improved 84.8% and 81.0% from baseline to 24 months for average and maximum pain. Modified Magnetic Resonance Observation of Cartilage Repair Tissue (MOCART) scoring showed that 7 of 10 subjects had complete defect repair and filling by 24 months. Biopsy staining for collagen II revealed integration and remodeling of HSAM into a mix of hyaline-like cartilage and fibrocartilage matrix.

CONCLUSION

This study provides evidence supporting the safety and efficacy of HSAM for treating symptomatic cartilage lesions. Subjects showed a high degree of defect fill and integration with the native cartilage and reported improvements in pain and function post-treatment. Results provide important original data for future clinical trials.

Freeze-dried bovine amniotic membrane as a cell delivery scaffold in a porcine model of radiation-induced chronic wounds

Background

Locoregional stem cell delivery is very important for increasing the efficiency of cell therapy. Amnisite BA (Amnisite) is a freeze-dried amniotic membrane harvested from bovine placenta. The objective of this study was to investigate the retention of cells of the stromal vascular fraction (SVF) on Amnisite and to determine the effects of cell-loaded Amnisite in a porcine radiation-induced chronic wound model.

Methods

Initially, experiments were conducted to find the most suitable hydration and incubation conditions for the attachment of SVF cells extracted from pig fat to Amnisite. Before seeding, SVFs were labeled with PKH67. The SVF cell-loaded Amnisite (group S), Amnisite only (group A), and polyurethane foam (group C) were applied to treat radiation-induced chronic wounds in a porcine model. Biopsy was performed at 10, 14, and 21 days post-operation for histological analysis.

Results

Retaining the SVF on Amnisite required 30 minutes for hydration and 1 hour for incubation. A PKH67 fluorescence study showed that Amnisite successfully delivered the SVF to the wounds. In histological analysis, group S showed increased re-epithelialization and revascularization with decreased inflammation at 10 days post-operation.

Conclusions

SVFs had acceptable adherence on hydrated Amnisite, with successful cell delivery to a radiation-induced chronic wound model.

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.

Proliferation ability of particulated juvenile allograft cartilage

Background

Particulated juvenile allograft cartilage (PJAC) has a good short-term clinical efficacy in repairing articular cartilage defects, but the proliferation ability of PJAC and the biological characteristics of transplanted cells after transplantation are still unclear.

Purpose

To study the cartilage proliferation ability of PJAC in repairing full-thickness cartilage defects and the reasons for proliferation to provide experimental evidence for its clinical application.

Study design

Controlled laboratory study.

Methods

Twenty Guizhou minipigs were randomly divided into the experimental group and control group. In all minipigs, an 8-mm cylindrical full-thickness cartilage defect was created in the femoral trochlea of one knee. The experimental group received PJAC transplantation from five juvenile donors of Guizhou minipigs (PJAC group; n = 10) and the control group received transplantation of autologous cartilage chips (ACC group; n = 10). Both groups were followed at 1 and 3 months after surgery, immunohistochemical evaluation of the tissue sections Ki-67 and Lin28 was conducted, the positive rate was calculated according to the staining, and the proliferation ability of PJAC was analyzed.

Results

All 20 Guizhou minipigs were followed, and there was no infection or incision healing disorder after surgery. By Ki-67 and Lin28 immunohistochemical tests, the positive rate of Ki-67 was 88.9 ± 0.2% in the PJAC group and 28.3 ± 3.6% in the ACC group at 1 month, and the difference was statistically significant (P < 0.05); the positive rate of Lin28 was 34.6 ± 3.3% in the PJAC group and 7.6 ± 1.4% in the ACC group at 1 month, and the difference was statistically significant (P < 0.05). At 3 months, the positive rates of Ki-67 in the PJAC group and ACC group were 53.6 ± 6.9% and 1.97 ± 0.3%, respectively (P < 0.05); the positive rates of Lin28 were 86.6 ± 3.3% and 1.4 ± 0.3%, respectively (P < 0.01).

Conclusion

A large animal model was established with Guizhou minipigs, and the expressions of Ki-67 protein and Lin28 protein detected by immunohistochemistry in the repaired transplanted tissue of the PJAC group were stronger than those of adult cartilage. The proliferation of PJAC within 3 months of transplantation was stronger than that of adult cartilage. The enhanced expression of Lin28 may be one of the mechanisms by which PJAC achieved stronger proliferation ability than adult cartilage. PJAC technology has shown good application prospects for repairing cartilage defects.

Adipose-derived stromal vascular fraction prevent bone bridge formation on growth plate injury in rat (in vivo studies) an experimental research

The growth plate is cartilage tissue found at the end of long bones in children, responsible for longitudinal bone growth. Injuries to the growth plate cartilage often lead to unwanted bony repair, resulting in growth disturbances such as limb length discrepancy and angulation deformity in children. There is currently no clinical treatment that can fully repair an injured growth plate. Tissue engineering is promising for regeneration of growth plate. Adipose-derived stromal vascular fraction highlight the promising potential as tissue engineering therapy for inducing regeneration of injured growth plate and able to reduce the formation of bony repair that can lead to deformity and limb length discrepancy. Using an animal model of growth plate injury, bone bridge formation is evaluated after 28 days using Enzyme-linked Immunoassay, radiology, histopathology and Immunofloresence examination. Radiological analyses performed by evaluation of grey value using ImageJ software and diameter bone bridge measured from the end to end distance between uninjured growth plate evaluated by histopatology examination. Enzyme-linked Immunoassay and immunofloresence are used to evaluate chondrocyte and chondrogenic marker within the defect. The result shows in group with Adipose-derived stromal vascular fraction have a significant lower bone bridge formation compare to positive control group. This current study represents the first work that has utilized this animal model to investigate whether Adipose-derived stromal vascular fraction can be used to initiate regeneration at the injured growth plate.

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Injuries to the growth plate cartilage often lead to unwanted bony repair, resulting in growth disturbances

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There is currently no clinical treatment that can fully repair an injured growth plate

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Tissue engineering is promising for regeneration of growth plate.

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Adipose-derived stromal vascular fraction (AD-SVF) highlight the promising potential as tissue engineering therapy

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AD-SVF decrease bone bridge formation on growth plate injuries model on Rat

The Healing Effect of Amniotic Membrane in Laryngeal Defects in Rabbit Model

OBJECTIVE

Fibrosis and scar formation following laryngeal repairing is a major concern. This study evaluated the efficacy of applying amniotic membrane (AM) as a biologic dressing to reduce fibrosis and inflammation and promote cartilage repair.

STUDY DESIGN

Experimental animal study.

METHODS

Nine male white Dutch rabbits were selected. A standard defect (5 mm) was created in right and left thyroid lamina. In the right side, two layers of AM were applied while the left side was kept intact for future comparison. Histologic examination with criteria of inflammation, fibrosis, and cartilage regeneration was performed 2, 4, and 6 weeks following AM application. All procedures were done according to animal ethics rules.

RESULTS

Histologic and gross examination showed that AM application was able to reduce inflammation and fibrosis and improve cartilage regeneration significantly.

CONCLUSION

As a useful intervention, AM application can reduce inflammation and fibrosis and enhance cartilage regeneration, following laryngeal defect repair.

LEVEL OF EVIDENCE

NA Laryngoscope, 131:E527-E533, 2021.

Assessment of fresh and preserved amniotic membrane for guided bone regeneration in mice

Thanks to its biological properties, the human amniotic membrane (HAM) can be used as a barrier membrane for guided bone regeneration (GBR). However, no study has assessed the influence of the preservation method of HAM for this application. This study aimed to establish the most suitable preservation method of HAM for GBR. Fresh (F), cryopreserved (C) lyophilized (L), and decellularized and lyophilized (DL) HAM were compared. The impact of preservation methods on collagen and glycosaminoglycans (GAG) content was evaluated using Masson's trichrome and alcian blue staining. Their suture retention strengths were assessed. In vitro, the osteogenic potential of human bone marrow mesenchymal stromal cells (hBMSCs) cultured on the four HAMs was evaluated using alkaline phosphatase staining and alizarin red quantification assay. In vivo, the effectiveness of fresh and preserved HAMs for GBR was assessed in a mice diaphyseal bone defect after 1 week or 1 month healing. Micro-CT and histomorphometric analysis were performed. The major structural components of HAM (collagen and GAG) were preserved whatever the preservation method used. The tearing strength of DL-HAM was significantly higher. In vitro, hBMSCs seeded on DL-HAM displayed a stronger ALP staining, and alizarin red staining quantification was significantly higher at Day 14. In vivo, L-HAM and DL-HAM significantly enhanced early bone regeneration. One month after the surgery, only DL-HAM slightly promoted bone regeneration. Several preserving methods of HAM have been studied for bone regeneration. Here, we have demonstrated that DL-HAM achieved the most promising results for GBR.

The effects of cryopreserved human amniotic membrane on fracture healing: Animal study

Objective

The aim of this study was to investigate the effects of human amniotic membrane (HAM) on fracture healing in an animal model.

Methods

Standard tibial diaphysial fractures were created in twenty-eight Wistar-Albino rats and treated with intramedullary Kirschner wire (K-wire) and HAM (HAM (+) group) or K-wire only (HAM (–) group). Fracture healing was evaluated by histological analysis, radiologic X-ray views and callus diameter measurements at 3rd and 6th weeks postoperatively.

Results

Fracture healing was histologically better in the HAM (+) group and the difference was statistically significant at both 3rd and 6th weeks postoperatively (p < 0.05). The highest histologic scores and entire woven bone formation (Huo Stage 8–9) were obtained at 6th weeks postoperatively in the HAM (+) group. Histological examination also revealed predominant fibrous tissue and partial cartilage formation (Huo Stage 2) at the postoperative 3rd week in the HAM (-) group. Equal amounts of woven bone and cartilage formation (Huo Stage 6–7) were observed at 3rd weeks postoperatively in the HAM (+) group and at 6th weeks postoperatively in the HAM (-) group. The callus diameters were greater in the HAM (+) group and the difference was statistically significant (p < 0.05) at 3rd and 6th weeks postoperatively. Although there was only a statistically significant difference (p < 0.05) at the postoperative 3rd week, radiological scores tended to be higher in the HAM (+) group at both the 3rd and 6th weeks postoperatively.

Conclusion

HAM is a cheap and easily accessible alternative biological material. HAM may be used to support surgical treatment of fractures, particularly where bone healing is expected to last longer.

Decellularized human amniotic membrane: From animal models to clinical trials

The efficacy of decellularized products for healing of acute and chronic wounds mostly relies on physical and chemical properties, processing methods and host response. Human Amniotic Membrane (HAM) is considered as an effective and highly used wound dressing in clinic. According to the proposed decellularization protocols for developing of HAM, we have compared different protocols to introduce the most efficient methods, which can be used as a functional dermal matrix. In this study, different methods of HAM decellularization were used to achieve an optimal process. After achievement of appropriate decellularized method in vitro the amniotic membrane were examined in term of animal in vivo study and human clinical trial. The results of in vitro and in vivo assay indicate that the HAMs which were prepared with peracetic acid (2 M) had a significantly different in term of GAGs quantification, DNA isolation and quantification, histological assessment, collagen analysis, Cell-Tissue Interaction Study and cytotoxicity (P < 0/05). Tissue samples treated with peracetic acid (2 M) were more acceptable than that of samples prepared with other protocols in terms of preserving natural components and structure and removing of cell fragments. The peracetic acid-processed HAM was further functionally evaluated through in vivo assessments that can further lead to tissue reconstruction within the human host.

Cartography of the mechanical properties of the human amniotic membrane

Because of its low immunogenicity, biological properties, and high availability, the Human Amniotic Membrane (HAM) is widely used in the clinic and in tissue engineering research. However, while its biological characteristics are well described, its mechanical properties remain understudied especially in terms of inter- and intra-HAM variability. To guide bioengineers in the use of this natural biomaterial, a detailed cartography of the HAM's mechanical properties was performed. Maximal force (Fmax) and strain at break (Smax) were identified as the relevant mechanical criteria for this study after a combined analysis of histological sections, thickness measurements after dehydration, and uniaxial tensile tests. Eight HAMs were studied by mechanical cartography using a standardized cutting protocol and sampling pattern. On average, 103 ± 10 samples were retrieved and tested per HAM. Intra-tissue variability highlighted the fact that there were two mechanically distinct areas (placental and peripheral) in each HAM. For all HAMs, placental HAM was significantly stronger by 82 ± 45% and more stretchable by 19 ± 6% than their peripheral counterparts. Our results also demonstrated that placental, but not peripheral, HAM presented isotropic mechanical properties. Thus, placental HAM can be a raw material of choice that could be favored especially in the development of tissue engineering products where mechanical properties play a key role.

Comparison of the impact of preservation methods on amniotic membrane properties for tissue engineering applications

Human amniotic membrane (hAM) is considered as an attractive biological scaffold for tissue engineering. For this application, hAM has been mainly processed using cryopreservation, lyophilization and/or decellularization. However, no study has formally compared the influence of these treatments on hAM properties. The aim of this study was to develop a new decellularization-preservation process of hAM, and to compare it with other conventional treatments (fresh, cryopreserved and lyophilized). The hAM was decellularized (D-hAM) using an enzymatic method followed by a detergent decellularization method, and was then lyophilized and gamma-sterilized. Decellularization was assessed using DNA staining and quantification. D-hAM was compared to fresh (F-hAM), cryopreserved (C-hAM) and lyophilized/gamma-sterilized (L-hAM) hAM. Their cytotoxicity on human bone marrow mesenchymal stem cells (hBMSCs) and their biocompatibility in a rat subcutaneous model were also evaluated. The protocol was effective as judged by the absence of nuclei staining and the residual DNA lower than 50 ng/mg. Histological staining showed a disruption of the D-hAM architecture, and its thickness was 84% lower than fresh hAM (p < 0.001). Despite this, the labeling of type IV and type V collagen, elastin and laminin were preserved on D-hAM. Maximal force before rupture of D-hAM was 92% higher than C-hAM and L-hAM (p < 0.01), and D-hAM was 37% more stretchable than F-hAM (p < 0.05). None of the four hAM were cytotoxic, and D-hAM was the most suitable scaffold for hBMSCs proliferation. Finally, D-hAM was well integrated in vivo. In conclusion, this new hAM decellularization process appears promising for tissue engineering applications.

Placental membrane grafts for urethral replacement in a rabbit model: a pilot study

PURPOSE

Several graft materials are available for use in the treatment of urethral stricture disease. Placental membrane is being used in a variety of settings as a graft in wound healing and tissue repair. We aim to evaluate the effect of implanting decellularized human placental membrane into rabbit urethras.

METHODS

Dorsal onlay graft urethroplasty using prepared human placental membrane was performed in 10 New Zealand White rabbits (Oryctolagus cuniculus). After 3 months, the rabbits underwent cystourethroscopy to evaluate urethral patency. The rabbits were then euthanized and the urethras examined for pathological findings.

RESULTS

All urethroplasties were performed without complication. There were no observed episodes of urinary retention, infection, or renal failure. Urethral patency was achieved in all rabbits 3 months postoperatively. Urothelial replacement of the placental membrane graft was observed in all rabbits without malignant transformation.

CONCLUSION

Dorsal onlay urethroplasty using decellularized human placental membrane can safely be performed in a rabbit model. This pilot study demonstrated urothelial replacement of human placental membrane in the rabbit urethra without stricture formation. Placental membrane is a promising biomaterial for urethral reconstruction.

Potential of Membranes Surrounding the Fetus as Immunoprotective Cell-Carriers for Allogeneic Transplantations

Background

Membranes surrounding the fetus play a crucial role in providing a physical and immunological barrier between a semiallogeneic fetus and mother during pregnancy. In this study, we tested whether cotransplantation of fetal membranes (FMs) and allogeneic donor cells would improve the retention and function of allografts in mice.

Methods

Intact and enzyme-digested membranes obtained from E18-E19 pregnant mice were subcutaneously cotransplanted with 10F7MN hybridoma cells that are of BALB/cByJ (Balb) origin and secrete anti-human CD235a antibody. Cells were transplanted into C57BL/6J (B6, allogeneic), Balb (syngeneic), and FVB/NJ (third-party) mice. Serum was collected after 1 and 3 weeks of cell transplantation and tested using flow cytometry for the presence of anti-human CD235a antibody. Immunosuppressive functions of membranes were further investigated by analyzing the cytokine profile of supernatants collected from allo-reactive mixed lymphocyte reactions (MLRs) using a multiplex cytokine assay.

Results

B6 mice transplanted with 10F7MN cells along with membranes syngeneic to the host had significantly higher levels of CD235a antibody when compared to B6 mice that received cells without membranes, allogenic membranes, or third-party membranes. Syngeneic membranes significantly inhibited T-cell proliferation in the presence of allogeneic stimuli and suppressed the release of Th1-cytokines such as IFNγ, TNFα, and IL-2 in MLRs. Additionally, increases in the levels of Th2-cytokines were found in MLRs containing membrane-derived cells.

Conclusions

Our study highlights the potential use of syngeneic FMs to act as potent cell-carriers that could improve graft retention as well as graft-specific immunoprotection during allograft transplantation.

Effects of the Human Amniotic Membrane on the Cartilage Graft: Prognosis and Absorption in White Rabbits

BACKGROUND

Cartilage grafts are generally accepted for the restoration and reconstruction of nasal contours. The main concern that plastic surgeons may need to address after surgery pertains to the resorption and disfigurement of the grafted cartilage, especially in allogenic and heterogenic grafts.

METHODS

A total of 12 white rabbits were divided into three groups according to the types of graft including autograft, allograft, and heterograft. We used three shapes of grafts, including block, crushed, and diced cartilage in the upper, middle, and lower rows. However, in each rabbit, these grafts were divided into two columns of wrapped and unwrapped grafts, with human amniotic membrane (HAM) grafted on each side of the rabbit’s back.

RESULTS

In total, 60 specimens underwent histopathological examination. No inflammation was observed in about 50% of the block-shaped conchal cartilages with HAM, and in 50%, less than 25 inflammatory cells per unit were seen. The prognosis and absorption of autograft specimens in block-shaped cartilages with HAM were significantly better compared with other shapes of cartilages with HAM and without HAM. The proliferation rate of fibroblasts in autograft and allograft specimens was more than that in heterograft specimens with HAM.

CONCLUSION

Our findings have demonstrated the new role of HAM in clinical applications, indicating that HAM may be used as a low-cost, easily accessible alternative for wrapping in cartilage grafts instead of fascia or surgicel in early future. It is useful for improving the long-term outcomes and decreasing the resorption rate.

Homing of adipose stem cells on the human amniotic membrane as a scaffold: A histological study

BACKGROUND

The human amniotic membrane (HAM) is a suitable and effective scaffold for cell culture and delivery, and adipose-derived stem cells (ADSCs) are an important source of stem cells for transplantation and chondrogenic differentiation.

OBJECTIVE

To assess the practicability of a cryopreserved HAM as a scaffold in cell proliferation and differentiation in vitro.

MATERIALS AND METHODS

In this experimental study, adipose tissue samples were harvested from the inguinal region of male patients aged 15-30 years. Flow cytometry was used to identify CD31, CD45, CD90, and CD105 markers in adipose stem cells. HAM was harvested from donor placenta after cesarean section, washed, trypsin-based decellularized trypsinized decellularized, and used as a scaffold via three methods: 1) ADSCs were differentiated into chondrocytes on cell culture flasks (monolayer method), and after 14 days of culture, the cells were transferred and cultured on both sides of the HAM; 2) ADSCs were cultured and differentiated directly on both sides of the HAM for 14 days (scaffold-mediated differentiation); and 3) chondrocytes were differentiated with micromass culture for 14 days, transferred on HAM, and tissue slides were histologically analyzed qualitatively.

RESULTS

Flow cytometry confirmed the presence of mesenchymal stem cells. Histological findings revealed that the cells adhered and grew well on the stromal layer of HAM. Among the three methods, scaffold-mediated differentiation of ADSCs showed the best results.

CONCLUSION

ADSCs have excellent attachment, viability, and differentiation capacity in the stromal side of HAM. Additionally, the direct culture and differentiation of ADSCs on HAM is more suitable than the culture of differentiated cells on HAM.

Spare Parts from Discarded Materials: Fetal Annexes in Regenerative Medicine

One of the main aims in regenerative medicine is to find stem cells that are easy to obtain and are safe and efficient in either an autologous or allogenic host when transplanted. This review provides an overview of the potential use of the fetal annexes in regenerative medicine: we described the formation of the annexes, their immunological features, the new advances in the phenotypical characterization of fetal annexes-derived stem cells, the progressions obtained in the analysis of both their differentiative potential and their secretoma, and finally, the potential use of decellularized fetal membranes. Normally discarded as medical waste, the umbilical cord and perinatal tissue not only represent a rich source of stem cells but can also be used as a scaffold for regenerative medicine, providing a suitable environment for the growth and differentiation of stem cells.

Human Amniotic Membrane and Amniotic Membrane-Derived Cells: How Far Are We from Their Use in Regenerative and Reconstructive Urology?

Human amniotic membrane (hAM) is the innermost layer of fetal membranes, which surrounds the developing fetus and forms the amniotic cavity. hAM and hAM-derived cells possess many properties that make them suitable for use in regenerative medicine, such as low immunogenicity, promotion of epithelization, anti-inflammatory properties, angiogenic and antiangiogenic properties, antifibrotic properties, antimicrobial properties, and anticancer properties. Many pathological conditions of the urinary tract lead to organ damage or complete loss of function. Consequently, the reconstruction or replacement of damaged organs is needed, which makes searching for new approaches in regenerative and reconstructive urology a necessity. The use of hAM for treating defects in kidneys, ureters, urinary bladder, and urethra was tested in vitro in cell cultures and in vivo in mice, rats, rabbits, cats, dogs, and also in humans. These studies confirmed the advantages and the potential of hAM for use in regenerative and reconstructive urology as stated above. However, they also pointed out a few concerns we have to take into consideration. These are (1) the lack of a standardized protocol in hAM preparation and storage, (2) the heterogeneity of hAM, and especially (3) low mechanical strength of hAM. Before any wider use of hAM for treating urological defects, the protocols for preparation and storage will need to be standardized, followed by more studies on larger animals and clinical trials, which will altogether extensively assess the potential of hAM use in urological patients.

Human amniotic membrane intra-articular injection prevents cartilage damage in an osteoarthritis model

Osteoarthritis (OA) is a degenerative joint disease that affects the soft tissues and bones of involved articulations as a result of deregulation between synthesis and extracellular matrix degradation in articular cartilage. The present study evaluated the effect of intra-articular injection of human amniotic membrane (AM) as a treatment in an OA animal model in the knee. Chemical OA was developed in the knees of New Zealand rabbits. Once OA was established, the right knees only were treated with an intra-articular injection of human AM, with the left knees considered as a negative control group. The evaluation was performed at 3 and 6 weeks post-treatment. At 3 weeks post-injection, the cartilage exhibited fibrillation, erosion, cracks and cell clusters in the negative control group, but not in the treated group (P=0.028). At 6 weeks post-injection, the left knees exhibited hypertrophy, cracks, cell clusters, decreased matrix staining and structure loss. However, the right knees exhibited cell clusters without evidence of disruption in cartilage integrity (P=0.015). These results suggested that the intra-articular injection of human AM delays histological changes of cartilage in OA.

Human amniotic membrane as differentiating matrix for in vitro chondrogenesis

Aim: The aim of the present study is to use human amniotic membrane (HAM) for in vitro chondrogenesis of placenta-derived mesenchymal stem cells (MSCs) and umbilical cord-derived MSCs. Materials & methods: MSCs from the placenta and umbilical cord were isolated, characterized by immunophenotyping and after analyzing their rate of proliferation, cytotoxicity and viability, chondrogenesis was performed on plastic adherent surface and on HAM. Results: Successfully isolated and characterized placenta-derived MSCs and umbilical cord-derived MSCs revealed positive expression of MSCs markers CD90, CD73, CD105 and CD49d, while they were negative for CD45. Both types of cells in the presence of chondrogenic induction medium on plastic adherent surface and HAM showed aggregates of proteoglycan and strong expression of COL2A1 (collagen 2) and ACAN1 (aggrecan). Conclusion: HAM supported proliferation as well as chondrogenesis of MSCs and provide novelty of HAM utilization as an efficient natural delivery matrix for stem cell transplantation.

The Science and Clinical Applications of Placental Tissues in Spine Surgery

STUDY DESIGN

Narrative literature review.

OBJECTIVES

Placental tissue, amniotic/chorionic membrane, and umbilical cord have seen a recent expansion in their clinical application in various fields of surgery. It is important for practicing surgeons to know the underlying science, especially as it relates to spine surgery, to understand the rationale and clinical indication, if any, for their usage.

METHODS

A literature search was performed using PubMed and MEDLINE databases to identify studies reporting the application of placental tissues as it relates to the practicing spine surgeon. Four areas of interest were identified and a comprehensive review was performed of available literature.

RESULTS

Clinical application of placental tissue holds promise with regard to treatment of intervertebral disc pathology, preventing epidural fibrosis, spinal dysraphism closure, and spinal cord injury; however, there is an overall paucity of high-quality evidence. As such, evidence-based guidelines for its clinical application are currently unavailable.

CONCLUSIONS

There is no high-level clinical evidence to support the application of placental tissue for spinal surgery, although it does hold promise for several areas of interest for the practicing spine surgeon. High-quality research is needed to define the clinical effectiveness and indications of placental tissue as it relates to spine surgery.

Human Amniotic Membrane: A Versatile Scaffold for Tissue Engineering

The human amniotic membrane (hAM) is a collagen-based extracellular matrix derived from the human placenta. It is a readily available, inexpensive, and naturally biocompatible material. Over the past decade, the development of tissue engineering and regenerative medicine, along with new decellularization protocols, has recast this simple biomaterial as a tunable matrix for cellularized tissue engineered constructs. Thanks to its biocompatibility, decellularized hAM is now commonly used in a broad range of medical fields. New preparation techniques and composite scaffold strategies have also emerged as ways to tune the properties of this scaffold. The current state of understanding about the hAM as a biomaterial is summarized in this review. We examine the processing techniques available for the hAM, addressing their effect on the mechanical properties, biodegradation, and cellular response of processed scaffolds. The latest in vitro applications, in vivo studies, clinical trials, and commercially available products based on the hAM are reported, organized by medical field. We also look at the possible alterations to the hAM to tune its properties, either through composite materials incorporating decellularized hAM, chemical cross-linking, or innovative layering and tissue preparation strategies. Overall, this review compiles the current literature about the myriad capabilities of the human amniotic membrane, providing a much-needed update on this biomaterial.

Supportive properties of basement membrane layer of human amniotic membrane enable development of tissue engineering applications

Human amniotic membrane (HAM) has been widely used as a natural scaffold in tissue engineering due to many of its unique biological properties such as providing growth factors, cytokines and tissue inhibitors of metalloproteinases. This study aimed at finding the most suitable and supportive layer of HAM as a delivery system for autologous or allogeneic cell transplantation. Three different layers of HAM were examined including basement membrane, epithelial and stromal layers. In order to prepare the basement membrane, de-epithelialization was performed using 0.5 M NaOH and its efficiency was investigated by histological stainings, DNA quantification, biomechanical testing and electron microscopy. Adipose-derived stromal cells (ASCs) and a human immortalized keratinocyte cell line (HaCaT) were seeded on the three different layers of HAM and cultured for 3 weeks. The potential of the three different layers of HAM to support the attachment and viability of cells were then monitored by histology, electron microscopy and (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Moreover, mechanical strengths of the basement membrane were assessed before and after cell culture. The results indicated that the integrity of extra cellular matrix (ECM) components was preserved after de-epithelialization and resulted in producing an intact basement amniotic membrane (BAM). Moreover, all three layers of HAM could support the attachment and proliferation of cells with no visible cytotoxic effects. However, the growth and viability of both cell types on the BAM were significantly higher than the other two layers. We conclude that growth stimulating effectors of BAM and its increased mechanical strength after culturing of ASCs, besides lack of immunogenicity make it an ideal model for delivering allogeneic cells and tissue engineering applications.

Human acellular amniotic membrane: A potential osteoinductive biomaterial for bone regeneration

Human acellular amniotic membrane is an acellular, naturally extracellular matrix material with various bioactive factors, which applied in tissue engineering in clinic. Several studies have applied human acellular amniotic membrane in skin and ocular surface tissue engineering to enhance tissue regeneration. However, the application of human acellular amniotic membrane in bone tissue engineering was rarely investigated. The aim of the current study was to investigate the osteoinductivity, angiogenesis and the early molecular changes of human acellular amniotic membrane to bone regeneration. Our results showed that human acellular amniotic membrane with excellent biocompatibility was beneficial for bone marrow mesenchymal stem cells proliferation and osteogenic differentiation. In rat femoral defect model, the existence of human acellular amniotic membrane significantly improved bone regeneration in the defects. The gene expression of CXCR-4, MCP-1, OC and CatK which were connected with cells recruitment and bone remodeling, was enhanced in the defects implanted with human acellular amniotic membrane. The results of this study suggest that human acellular amniotic membrane is an osteoinductive biomaterial for bone regeneration.

The application of decellularized human term fetal membranes in tissue engineering and regenerative medicine (TERM)

Tissue engineering and regenerative medicine (TERM) is a field that applies biology and engineering principles to "restore, maintain or repair a tissue after injury". Besides the potential to treat various diseases, these endeavours increase our understanding of fundamental cell biology. Although TERM has progressed rapidly, engineering a whole organ is still beyond our skills, primarily due to the complexity of tissues. Material science and current manufacturing methods are not capable of mimicking this complexity. Therefore, many researchers explore the use of naturally derived materials that maintain important biochemical, structural and mechanical properties of tissues. Consequently, employing non-cellular components of tissues, particularly the extracellular matrix, has emerged as an alternative to synthetic materials. Because of their complexity, decellularized tissues are not as well defined as synthetic materials but they provide cells with a microenvironment that resembles their natural niche. Decellularized tissues are produced from a variety of sources, among which the fetal membranes are excellent candidates since their supply is virtually unlimited, they are readily accessible with minimum ethical concerns and are often discarded as a biological waste. In this review, we will discuss various applications of decellularized fetal membranes as substrates for the expansion of stem cells, their use as two and three-dimensional scaffolds for tissue regeneration, and their use as cell delivery systems. We conclude that fetal membranes have great potential for use in TERM.

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.

Rare mutations and potentially damaging missense variants in genes encoding fibrillar collagens and proteins involved in their production are candidates for risk for preterm premature rupture of membranes

Preterm premature rupture of membranes (PPROM) is the leading identifiable cause of preterm birth with ~ 40% of preterm births being associated with PPROM and occurs in 1% - 2% of all pregnancies. We hypothesized that multiple rare variants in fetal genes involved in extracellular matrix synthesis would associate with PPROM, based on the assumption that impaired elaboration of matrix proteins would reduce fetal membrane tensile strength, predisposing to unscheduled rupture. We performed whole exome sequencing (WES) on neonatal DNA derived from pregnancies complicated by PPROM (49 cases) and healthy term deliveries (20 controls) to identify candidate mutations/variants. Genotyping for selected variants from the WES study was carried out on an additional 188 PPROM cases and 175 controls. All mothers were self-reported African Americans, and a panel of ancestry informative markers was used to control for genetic ancestry in all genetic association tests. In support of the primary hypothesis, a statistically significant genetic burden (all samples combined, SKAT-O p-value = 0.0225) of damaging/potentially damaging rare variants was identified in the genes of interest-fibrillar collagen genes, which contribute to fetal membrane strength and integrity. These findings suggest that the fetal contribution to PPROM is polygenic, and driven by an increased burden of rare variants that may also contribute to the disparities in rates of preterm birth among African Americans.

A Human Amnion-Derived Extracellular Matrix-Coated Cell-Free Scaffold for Cartilage Repair: In Vitro and In Vivo Studies

OBJECTIVE

Extracellular matrix (ECM) derived from human amniotic mesenchymal cells (HAMs) has various biological activities. In this study, we developed a novel HAM-derived ECM-coated polylactic-co-glycolic acid (ECM-PLGA) scaffold, examined its property on mesenchymal cells, and investigated its potential as a cell-free scaffold for cartilage repair.

MATERIALS AND METHODS

ECM-PLGA scaffolds were developed by inoculating HAM on a PLGA. After decellularization by irradiation, accumulated ECM was examined. Exogenous cell growth and differentiation of rat mesenchymal stem cells (MSCs) on the ECM-PLGA were analyzed in vitro by cell attachment/proliferation assay and reverse transcription-polymerase chain reaction. The cell-free ECM-PLGA scaffolds were implanted into osteochondral defects in the trochlear groove of rat knees. After 4, 12, or 24 weeks, the animals were sacrificed and the harvested tissues were examined histologically.

RESULTS

The ECM-PLGA contained ECM that mimicked natural amniotic stroma that contains type I collagen, fibronectin, hyaluronic acid, and chondroitin sulfates. The ECM-PLGA showed excellent properties of cell attachment and proliferation. MSCs inoculated on the ECM-PLGA scaffold showed accelerated type II collagen mRNA expression after 3 weeks in culture. The ECM-PLGA implanted into an osteochondral defect in rat knees induced gradual tissue regeneration and resulted in hyaline cartilage repair, which was better than that in the empty control group.

CONCLUSION

These in vitro and in vivo experiments show that the cell-free scaffold composed of HAM-derived ECM and PLGA provides a favorable growth environment for MSCs and facilitates the cartilage repair process. The ECM-PLGA may become a "ready-made" biomaterial for cartilage repair therapy.

Tissue engineering for neurodegenerative diseases using human amniotic membrane and umbilical cord

Regenerative medicine, based on the use of stem cells, scaffolds and growth factors, has the potential to be a good approach for restoring damaged tissues of the central nervous system. This study investigated the use of human amniotic mesenchymal stem cells (hAMSC), human amniotic epithelial stem cells (hAESC), and human Wharton's jelly mesenchymal stem cells (hWJMSC) derived from human umbilical cord as a source of stem cells, and the potential of the human amniotic membrane (HAM) as a scaffold and/or source of growth factors to promote nerve regeneration. The hAMSC and hAESC obtained from HAM and the hWJMSC from umbilical cords were cultured in induction medium to obtain neural-like cells. The morphological differentiation of hAMSC, hAESC and hWJMSC into neural-like cells was evident after 4-5 days, when they acquired an elongated and multipolar shape, and at 21 days, when they expressed neural and glial markers. On other way, the HAM was completely decellularized without affecting the components of the basement membrane or the matrix. Subsequently, hAMSC, hAESC and hWJMSC differentiated into neural-like cells were seeded onto the decellularized HAM, maintaining their morphology. Finally, conditioned media from the HAM allowed proliferation of hAMSC, hAESC and hWJMSC differentiated to neural-like cells. Both HAM and umbilical cord are biomaterials with great potential for use in regenerative medicine for the treatment of neurodegenerative diseases.

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.

Angiogenic potential of extracellular matrix of human amniotic membrane

Combination between tissue engineering and other fields has brought an innovation in the area of regenerative medicine which ultimate aims are to repair, improve, and produce a good tissue construct. The availability of many types of scaffold, both synthetically and naturally have developed into many outstanding end products that have achieved the general objective in tissue engineering. Interestingly, most of this scaffold emulates extracellular matrix (ECM) characteristics. Therefore, ECM component sparks an interest to be explored and manipulated. The ECM featured in human amniotic membrane (HAM) provides a suitable niche for the cells to adhere, grow, proliferate, migrate and differentiate, and could possibly contribute to the production of angiogenic micro-environment indirectly. Previously, HAM scaffold has been widely used to accelerate wound healing, treat bone related and ocular diseases, and involved in cardiovascular repair. Also, it has been used in the angiogenicity study, but with a different technical approach. In addition, both side of HAM could be used in cellularised and decellularised conditions depending on the objectives of a particular research. Therefore, it is of paramount importance to investigate the behavior of ECM components especially on the stromal side of HAM and further explore the angiogenic potential exhibited by this scaffold.

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.

Topical Review: Use of Fetal Tissue in Foot and Ankle Surgery

Fetal tissues are well known for their therapeutic potential. They contain numerous growth factors, cytokines, and matrix components that promote regeneration of tissues while downregulating inflammation and scar formation. As a result, use of these treatments has expanded over the previous 20 years throughout various surgical specialties, including orthopaedics. With improved methods of sterilization, processing, and storage, surgeons need to be informed about the potential benefits of fetal tissue in foot and ankle surgery. The aim of this review is to provide a brief historical background, basic anatomy and physiology, and a current review of the literature in regard to chronic wounds, diabetic foot ulcerations, plantar fasciitis, tendon repair, adhesion prevention, nerve repair, and bone healing.

LEVELS OF EVIDENCE

Level V: Expert Opinion.

Dehydrated human amnion/chorion membrane regulates stem cell activity in vitro

Human‐derived placental tissues have been shown in randomized clinical trials to be effective for healing chronic wounds, and have also demonstrated the ability to recruit stem cells to the wound site in vitro and in vivo. In this study, PURION^® Processed dehydrated human amnion/chorion membrane allografts (dHACM, EpiFix^®, MiMedx Group, Marietta, GA) were evaluated for their ability to alter stem cell activity in vitro. Human bone marrow mesenchymal stem cells (BM‐MSCs), adipose derived stem cells (ADSCs), and hematopoietic stem cells (HSCs) were treated with soluble extracts of dHACM tissue, and were evaluated for cellular proliferation, migration, and cytokine secretion. Stem cells were analyzed for cell number by DNA assay after 24 h, closure of an acellular zone using microscopy over 3 days, and soluble cytokine production in the medium of treated stem cells was analyzed after 3 days using a multiplex ELISA array. Treatment with soluble extracts of dHACM tissue stimulated BM‐MSCs, ADSCs, and HSCs to proliferate with a significant increase in cell number after 24 h. dHACM treatment accelerated closure of an acellular zone by ADSCs and BM‐MSCs after 3 days, compared to basal medium. BM‐MSCs, ADSCs, and HSCs also modulated endogenous production of a number of various soluble signals, including regulators of inflammation, mitogenesis, and wound healing. dHACM treatment promoted increased proliferation and migration of ADSCs, BM‐MSCs, and HSCs, along with modulation of secreted proteins from those cells. Therefore, dHACM may impact wound healing by amplifying host stem cell populations and modulating their responses in treated wound tissues. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 104B: 1495–1503, 2016.

Stem cells from fetal membranes and amniotic fluid: markers for cell isolation and therapy

Stem cell therapy is in constant need of new cell sources to conceive regenerative medicine approaches for diseases that are still without therapy. Scientists drew the attention toward amniotic membrane and amniotic fluid stem cells, since these sources possess many advantages: first of all as cells can be extracted from discarded foetal material it is inexpensive, secondly abundant stem cells can be obtained and finally, these stem cell sources are free from ethical considerations. Many studies have demonstrated the differentiation potential in vitro and in vivo toward mesenchymal and non-mesenchymal cell types; in addition the immune-modulatory properties make these cells a good candidate for allo- and xenotransplantation. This review offers an overview on markers characterisation and on the latest findings in pre-clinical or clinical setting of the stem cell populations isolated from these sources.

Intra-articular injection of micronized dehydrated human amnion/chorion membrane attenuates osteoarthritis development

INTRODUCTION

Micronized dehydrated human amnion/chorion membrane (μ-dHACM) is derived from donated human placentae and has anti-inflammatory, low immunogenic and anti-fibrotic properties. The objective of this study was to quantitatively assess the efficacy of μ-dHACM as a disease modifying intervention in a rat model of osteoarthritis (OA). It was hypothesized that intra-articular injection of μ-dHACM would attenuate OA progression.

METHODS

Lewis rats underwent medial meniscal transection (MMT) surgery to induce OA. Twenty four hours post-surgery, μ-dHACM or saline was injected intra-articularly into the rat joint. Naïve rats also received μ-dHACM injections. Microstructural changes in the tibial articular cartilage were assessed using equilibrium partitioning of an ionic contrast agent (EPIC-μCT) at 21 days post-surgery. The joint was also evaluated histologically and synovial fluid was analyzed for inflammatory markers at 3 and 21 days post-surgery.

RESULTS

There was no measured baseline effect of μ-dHACM on cartilage in naïve animals. Histological staining of treated joints showed presence of μ-dHACM in the synovium along with local hypercellularity at 3 and 21 days post-surgery. In MMT animals, development of cartilage lesions at 21 days was prevented and number of partial erosions was significantly reduced by treatment with μ-dHACM. EPIC-μCT analysis quantitatively showed that μ-dHACM reduced proteoglycan loss in MMT animals.

CONCLUSIONS

μ-dHACM is rapidly sequestered in the synovial membrane following intra-articular injection and attenuates cartilage degradation in a rat OA model. These data suggest that intra-articular delivery of μ-dHACM may have a therapeutic effect on OA development.

Acellular amniotic membrane: an appropriate scaffold for fibroblast proliferation

BACKGROUND

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

AIM

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Cryopreservation effect on proliferative and chondrogenic potential of human chondrocytes isolated from superficial and deep cartilage

Objectives:

To compare the proliferative and chondrogenic potential of fresh and frozen chondrocytes isolated from superficial and deep articular cartilage biopsies.

Materials and Methodology:

The study included 12 samples of fresh and frozen healthy human knee articular cartilage. Cell proliferation was tested at 3, 6 and 9 days. Studies of mRNA quantification, protein expression and immunofluorescence for proliferation and chondrogenic markers were performed.

Results:

Stimulation of fresh and frozen chondrocytes from both superficial and deep cartilage with fetal bovine serum produced an increase in the proliferative capacity compared to the non-stimulated control group. In the stimulated fresh cells group, the proliferative capacity of cells from the deep biopsy was greater than that from cells from the superficial biopsy (0.046 vs 0.028, respectively, p<0.05). There was also a significant difference between the proliferative capacity of superficial zone fresh (0.028) and frozen (0.051) chondrocytes (p<0.05). CCND1 mRNA and protein expression levels, and immunopositivity for Ki67 revealed a higher proliferative capacity for fresh articular chondrocytes from deep cartilage. Regarding the chondrogenic potential, stimulated fresh cells showed higher SOX9 and Col II expression in chondrocytes from deep than from superficial zone (p<0.05, T student test).

Conclusions:

The highest rate of cell proliferation and chondrogenic potential of fresh chondrocytes was found in cells obtained from deep cartilage biopsies, whereas there were no statistically significant differences in proliferative and chondrogenic capacity between biopsy origins with frozen chondrocytes. These results indicate that both origin and cryopreservation affect the proliferative and chondrogenic potential of chondrocytes.

Engineering membrane scaffolds with both physical and biomolecular signaling

We report on the combination of a top-down and bottom-up approach to develop thin bioactive membrane scaffolds based on functional elastin-like polymers (ELPs). Our strategy combines ELP cross-linking and assembly, and a variety of standard and novel micro/nanofabrication techniques to create self-supporting membranes down to ∼500 nm thick that incorporate both physical and biomolecular signals, which can be easily tailored for a specific application. In this study we used an ELP that included the cell-binding motif arginine-glycine-aspartic acid-serine (RGDS). Furthermore, fabrication processes were developed to create membranes that exhibited topographical patterns with features down to 200 nm in lateral dimensions and up to 10 μm in height on either one or both sides, uniform and well-defined pores, or multiple ELP layers. A variety of processing parameters were tested in order to optimize membrane fabrication, including ELP and cross-linker concentration, temperature, reaction time and ambient humidity. Membrane micro/nanopatterning, swelling and stiffness were characterized by atomic force microscopy, nanoindentation tests and scanning electron microscopy. Upon immersion in phosphate-buffered saline and an increase in temperature from 25 to 40°C, membranes exhibited a significant increase in surface stiffness, with the reduced Young's modulus increasing with temperature. Finally, rat mesenchymal stem cells were cultured on thin RGDS-containing membranes, which allowed cell adhesion, qualitatively enhanced spreading compared to membranes without RGDS epitopes and permitted proliferation. Furthermore, cell morphology was drastically affected by topographical patterns on the surface of the membranes.