Manufacture of a Cell-free Amnion Matrix Scaffold that Supports Amnion Cell Outgrowth In Vitro

In vitro and in vivo evaluation of a modified porcine acellular dermal matrix for soft tissue augmentation

OBJECTIVES

To evaluate the effects of a modified porcine acellular dermal matrix (P-ADM), subepithelial connective tissue graft (SCTG) and other commercial bovine acellular dermal matrix membrane materials (B-ADM) on gingival soft tissue augmentation in the oral esthetic zone.

MATERIAL AND METHODS

The characteristics of P-ADM were observed by scanning electron microscope (SEM), Hematoxylin and eosin (H&E) and Masson's trichrome staining (Masson staining). The biocompatibility of P-ADM was verified by CCK8, phalloidin and living/dead cell staining. Beagle dog models were constructed and the thickness of gingiva was analyzed by the intraoral scanner. The morphology was observed by H&E and Masson staining.

RESULTS

Scanning electron microscopy, H&E and Masson staining showed that the P-ADM was mainly composed of collagen fibers, with no component of nuclear. The results of CCK8, phalloidin and living/dead cell staining indicated that the P-ADM had good cytocompatibility and no cytotoxicity. Human gingival fibroblasts were able to adhere and stretch on the surface of the material with pseudopodia. The SCTG group outperformed the B-ADM and P-ADM groups in terms of effectiveness, according to the analysis of digital oral scanning data at various time points following incremental soft tissue surgery. Compared with the B-ADM group, the effect of soft tissue increment was better in the P-ADM group.

CONCLUSIONS

P-ADM, as a biocompatible biomaterial, can be used as an alternative biomaterial for oral soft tissue thickening. However, the results of this study need to be verified by more clinical trials.

Amniotic membrane attenuates heterotopic ossification following high-dose bone morphogenetic protein-2 treatment of segmental bone defects

Treatment of large bone defects with supraphysiological doses of bone morphogenetic protein-2 (BMP-2) has been associated with complications including heterotopic ossification (HO), inflammation, and pain, presumably due to poor spatiotemporal control of BMP-2. We have previously recapitulated extensive HO in our rat femoral segmental defect model by treatment with high-dose BMP-2 (30 μg). Using this model and BMP-2 dose, our objective was to evaluate the utility of a clinically available human amniotic membrane (AM) around the defect space for guided bone regeneration and reduction of HO. We hypothesized that AM surrounding collagen sponge would attenuate heterotopic ossification compared with collagen sponge alone. In vitro, AM retained more BMP-2 than a synthetic poly(ε-caprolactone) membrane through 21 days. In vivo, as hypothesized, the collagen + AM resulted in significantly less heterotopic ossification and correspondingly, lower total bone volume (BV), compared with collagen sponge alone. Although bone formation within the defect was delayed with AM around the defect, by 12 weeks, defect BVs were equivalent. Torsional stiffness was significantly reduced with AM but was equivalent to that of intact bone. Collagen + AM resulted in the formation of dense fibrous tissue and mineralized tissue, while the collagen group contained primarily mineralized tissue surrounded by marrow-like structures. Especially in conjunction with high doses of growth factor delivered via collagen sponge, these findings suggest AM may be effective as an overlay adjacent to bone healing sites to spatially direct bone regeneration and minimize heterotopic ossification.

Biomaterial-based treatments for the prevention of preterm birth after iatrogenic rupture of the fetal membranes

Minimally invasive interventions to ameliorate or correct fetal abnormalities are becoming a clinical reality. However, the iatrogenic premature preterm rupture of the fetal membranes (FMs) (iPPROM), which may result in...

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

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

Sustained delivery of 17β-estradiol by human amniotic extracellular matrix (HAECM) scaffold integrated with PLGA microspheres for endometrium regeneration

The endometrial injury usually results in intrauterine adhesions (IUAs). However, there is no effective treatment to promote the regeneration of the endometrium currently. The decellularized amnion membrane (AM) is a promising material in human tissue repair and regeneration due to its biocompatibility, biodegradability, as well as the preservation of abundant bioactive components. Here, an innovative drug-delivering system based on human amniotic extracellular matrix (HAECM) scaffolds were developed to facilitate endometrium regeneration. The 17β-estradiol (E2) loaded PLGA microspheres (E2-MS) were well dispersed in the scaffolds without altering their high porosity. E2 released from E2-MS-HAECM scaffolds in vitro showed a decreased initial burst release followed with a sustained release for 21 days, which coincided with the female menstrual cycle. Results of cell proliferation suggested E2-MS-HAECM scaffolds had good biocompatibility and provided more biologic guidance of endometrial cell proliferation except for mechanical supports. Additionally, the mRNA expression of growth factors in endometrial cells indicated that HAECM scaffolds could upregulate the expression of EGF and IGF-1 to achieve endometrium regeneration. Therefore, these advantages provide the drug-loaded bioactive scaffolds with new choices for the treatments of IUAs.

Effect of Acellular Amniotic Membrane Matrix Patch on Healing of Cut Surface After Sleeve Gastrectomy in Rats

Background: The aim of this study was to evaluate the effect of acellular amniotic membrane matrix patch on healing cut surface after sleeve gastrectomy in rats. Methods: Thirty male Wistar albino rats were divided into three groups: control (n = 10), Experiment-1 (n = 10), and Experiment-2 (n = 10) groups. Control group rats underwent only sleeve gastrectomy with primary gastrorrhaphy. Experiment-1 group rats underwent sleeve gastrectomy, primary gastrorrhaphy and covered with acellular amniotic membrane matrix patch. Experiment-2 group rats underwent sleeve gastrectomy, incomplete primary gastrorrhaphy and covered with acellular amniotic membrane matrix patch. All rats were sacrificed on the fifth postoperative day. Macroscopic findings and histopathologic alterations were evaluated and compared. Results: There was a statistically significant difference between levels of PMNs, granulation formation and vascularization, distributions of edema, type of mucosal epithelium, and fibroblastic proliferation according to groups (p < 0.05). The PMNs level in the Experiment-1 group was significantly lower than the control group (p < 0.05). In experiment groups, the level of granulation tissue, vascularization and fibroblastic proliferation was significantly higher than the control group (p < 0.05). The levels of edema and type of mucosal epithelium of the experiment groups were significantly lower than the control group (p < 0.05). Conclusion: Covering sleeve gastrectomy cut surface area with acellular amniotic membrane matrix results better healing. Moreover, acellular amniotic membrane matrix provides safe healing even in incomplete sutured area.

Skin Mast Cell Promotion in Random Skin Flaps in Rats using Bone Marrow Mesenchymal Stem Cells and Amniotic Membrane

Background

Skin flap procedures are employed in plastic surgery, but failure can lead to necrosis of the flap. Studies have used bone marrow mesenchymal stem cells (BM-MSCs) to improve flap viability. BM-MSCs and acellular amniotic membrane (AAM) have been introduced as alternatives. The objective of this study was to evaluate the effect of BM-MSCs and AAM on mast cells of random skin flaps (RSF) in rats.

Methods

RSFs (80 × 30 mm) were created on 40 rats that were randomly assigned to one of four groups, including (I) AAM, (II) BM-MSCs, (III) BM-MSCs/AAM, and (IV) saline (control). Transplantation was carried out during the procedure (zero day). Flap necrosis was observed on day 7, and skin samples were collected from the transition line of the flap to evaluate the total number and types of mast cells. The development and the total number of mast cells were related to the development of capillaries.

Results

The results of one-way ANOVA indicated that there was no statistically significant difference between the mean numbers of mast cell types for different study groups. However, the difference between the total number of mast cells in the study groups was statistically significant (p = 0.001).

Conclusion

The present study suggests that the use of AAM/BM-MSCs can improve the total number of mast cells and accelerate the growth of capillaries at the transient site in RSFs in rats.

Human Amnion Membrane: Potential Applications in Oral and Periodontal Field

Human amniotic membrane (HAM) is derived from the fetal membranes which consist of the inner amniotic membrane made of single layer of amnion cells fixed to collagen-rich mesenchyme attached to chorion. HAM has low immunogenicity, anti-inflammatory properties and their cells can be isolated without the sacrifice of human embryos. Amniotic membrane has biological properties which are important for the experimental and clinical applications in managing patients of various medical specialties. Abundant, natural and wonderful biomembrane not only protects the foetus but also has various clinical applications in the field of dermatology, ophthalmology, ENT surgery, orthopedics and dental surgery. As it is discarded post-partum it may be useful for regenerative medicine and cell therapy to treat damaged or diseased tissues.

Effects of Acellular Amniotic Membrane Matrix and Bone Marrow-Derived Mesenchymal Stem Cells in Improving Random Skin Flap Survival in Rats

BACKGROUND

The necrotic skin flap represents a great challenge in plastic and reconstructive surgery. In this study, we evaluated the effect of bioscaffolds, acellular amniotic membranes (AAMs), and bone marrow-derived mesenchymal stem cells (BM-MSCs) on random skin flap (RSF) survival in rats by applying a cell-free extracellular matrix scaffold as a supportive component for the growth and proliferation of BM-MSCs on RSFs. AAM matrix scaffolds were created by incubating AMs in ethylenediaminetetraacetic acid 0.05% at 37°C, and cell scrapers were used.

OBJECTIVES

The aim of the present study was to assess the effect of AAM as a scaffold in TE, and combined with transplanted BM-MSCs, on the survival of RSFs and on the biomechanical parameters of the incision-wound flap margins 7 days after flap elevation.

MATERIALS AND METHODS

BM-MSCs and AAMs were transplanted into subcutaneous tissue in the flap area. On the 7th postoperative day, the surviving flap areas were measured using digital imaging software, and the flap tissue was collected for evaluation. Forty rats were randomly divided into four groups of 10 each: group 1 received an AAM injection; group 2 underwent BM-MSC transplantation; group 3 received both AAM injection + BM-MSC transplantation; and group 4 was the control group, receiving only saline.

RESULTS

The survival area in the AAM/BM-MSC group was significantly higher than in the control group (18.49 ± 1.58 versus 7.51 ± 2.42, P < 0.05). The biomechanical assessment showed no significant differences between the experimental groups and the control group (P > 0.05), and there was no correlation with flap survival.

CONCLUSIONS

Our findings showed that the treatment of flaps with BM-MSC and AAM transplantations significantly promoted flap survival compared to a control group. The viability of the flap was improved by combining BM-MSCs with AAM matrix scaffolds.

Decellularization of fibroblast cell sheets for natural extracellular matrix scaffold preparation

The application of cell-derived extracellular matrix (ECM) in tissue engineering has gained increasing interest because it can provide a naturally occurring, complex set of physiologically functional signals for cell growth. The ECM scaffolds produced from decellularized fibroblast cell sheets contain high amounts of ECM substances, such as collagen, elastin, and glycosaminoglycans. They can serve as cell adhesion sites and mechanically strong supports for tissue-engineered constructs. An efficient method that can largely remove cellular materials while maintaining minimal disruption of ECM ultrastructure and content during the decellularization process is critical. In this study, three decellularization methods were investigated: high concentration (0.5 wt%) of sodium dodecyl sulfate (SDS), low concentration (0.05 wt%) of SDS, and freeze-thaw cycling method. They were compared by characterization of ECM preservation, mechanical properties, in vitro immune response, and cell repopulation ability of the resulted ECM scaffolds. The results demonstrated that the high SDS treatment could efficiently remove around 90% of DNA from the cell sheet, but significantly compromised their ECM content and mechanical strength. The elastic and viscous modulus of the ECM decreased around 80% and 62%, respectively, after the high SDS treatment. The freeze-thaw cycling method maintained the ECM structure as well as the mechanical strength, but also preserved a large amount of cellular components in the ECM scaffold. Around 88% of DNA was left in the ECM after the freeze-thaw treatment. In vitro inflammatory tests suggested that the amount of DNA fragments in ECM scaffolds does not cause a significantly different immune response. All three ECM scaffolds showed comparable ability to support in vitro cell repopulation. The ECM scaffolds possess great potential to be selectively used in different tissue engineering applications according to the practical requirement.

Second-harmonic generation microscopy for assessment of mesenchymal stem cell-seeded acellular dermal matrix in wound-healing

Direct intra-skin injection of mesenchymal stem cells (MSCs) and the use of biomaterial scaffolds for grafts are both promising approaches of skin wound repair, however they still cannot generate skin that completely resembles the natural skin structures. In this study, we combined these two approaches by using acellular dermal matrix (ADM) recellularized with MSCs to repair cutaneous wounds in a murine model and two-photon fluorescence (TPF) microscopy and second-harmonic generation (SHG) microscopy to assess the effects of this therapy on wound healing. Bone marrow-derived mesenchymal stem cells (BM-MSCs) were tagged with GFP and seeded into ADM (ADM-MSC) via MSC and ADM co-culture. ADM-MSC, ADM or saline was applied to murine excisional skin wounds and wound-healing was evaluated by histological examination on days 7, 14, 21 and TFP microscopy on days 1, 3, 5 and 21 post-treatment. ADM-MSC promoted healing significantly more than treatment with ADM or saline alone, as it led to substantial neovascularization and complete skin appendage regeneration. Furthermore, the SHG microscopic imaging technique proved to be a useful tool for monitoring changes in the collagen network at the wound site during the healing process and assessing the effects of different therapies.

Engineered cell instructive matrices for fetal membrane healing

Iatrogenic preterm prelabour rupture of fetal membranes (iPPROM) occurs in 6-45% of the cases after fetoscopic procedures, posing a significant threat to fetal survival and well-being. The number of diagnostic and therapeutic prenatal interventions available is increasing, thus developing treatment options for iPPROM is becoming more important than ever before. Fetal membranes exhibit very restricted regeneration and little is known about factors which might modulate their healing potential, rendering various materials and strategies to seal or heal fetal membranes pursued over the past decades relatively fruitless. Additionally, biocompatible materials with tunable in vivo stability and mechanical and biological properties have not been available. Using poly(ethylene glycol)-based biomimetic matrices, we provide evidence that, upon presentation of appropriate biological cues in three dimensions, mesenchymal progenitor cells from the amnion can be mobilized, induced to proliferate and supported in maintaining their native extracellular matrix production, thus creating a suitable environment for healing to take place. These data suggest that engineering materials with defined mechanical and biochemical properties and the ability to present migration- and proliferation-inducing factors, such as platelet-derived growth factor, basic fibroblast growth factor or epidermal growth factor, could be key in resolving the clinical problem of iPPROM and allowing the field of fetal surgery to move forward.

In vitro characterization of patches of human mesenchymal stromal cells

Stem cells may represent an excellent strategy to improve the healing of skin ulcers. Today the administration mode of stem cells to skin defects remains unsatisfactory. Delivering stem cells with topical treatments represents a new strategy and answering the patients' need. Mesenchymal stromal cells (MSC) have been shown to improve wound healing of cutaneous lesions and amniotic membrane (AM) is known to represent a natural scaffold for cells. The aim of this study is to develop a tissue-engineered product combining MSC and AM for clinical use. In this work we investigated whether the stromal matrix of intact human AM could constitute a scaffold for human MSC derived from either bone marrow (BM) or adipose tissue (AT). For this purpose, clinical-grade AM, MSC, and culture medium were used. We performed experiments of short-term adherence and proliferation for 15 days after the seeding of the cells. Morphological aspects and secretion profiles of MSC onto AM were studied, respectively, by scanning electron microscopy and Luminex analysis. Results demonstrated that the stromal matrix allow the adherence in much greater amount of MSC from BM or AT compared to 2D material. Experiments of proliferation showed that both kinds of MSC could proliferate on the stromal matrix and remain viable 15 days after the seeding of the cells. The 3D analysis of MSC culture demonstrated that both types of MSC invaded the stromal matrix and grew in multiple layers while retaining their fibroblastic morphology. By studying the secretion profile of MSC onto the stromal matrix, we found that both kinds of MSC secrete important cytokines and growth factors for wound healing of cutaneous lesions, such as vascular endothelial growth factor, hepatocyte growth factor, and basic fibroblast growth factor. In conclusion, these results suggest that the stromal matrix of AM seeded with MSC represents a bioactive scaffold that should be evaluated in patients with a nonhealing cutaneous wound.

Tuning scaffold mechanics by laminating native extracellular matrix membranes and effects on early cellular remodeling

At approximately 50 µm thin, the human amniotic membrane (hAM) has been shown to be a versatile biomaterial with applications ranging from ocular transplants to skin and nerve regeneration. These investigations describe laminating layers of the hAM into a multilayered, conformation creating a thicker, more robust biomaterial for applications requiring more supportive structures. Amniotic membranes were decellularized using 4 M NaCl and prepared as either flat single-layered sheets or rolled into concentric five-layered configurations. Constructs were seeded with human vascular smooth muscle cells and cultured over 40 days to quantify biological and mechanical changes that occurred during early remodeling events. By day 40 single-layered constructs displayed a decreasing trend in cellular densities and glycosaminoglycan (GAG) concentration, comparative to multilayered constructs with increasing cell densities (from 9.1 to 32 × 10(6) cells/g) and GAG concentrations (from 6.07 to 17.4 mg/g). Oxygen diffusion was calculated and found to be sufficient to maintain cell populations through the constructs full thickness. Although an overall decrease in the modulus of elasticity was noted, the modulus in the failure range of rolled constructs stabilized at values 25 times higher than single-layered constructs. Rolled constructs typically displayed an upregulation of contractile and matrix remodeling markers (α-actin, SM22 and type 1 collagen, MMP-2 respectively) indicating biological adaptation. Considerable design flexibility can be achieved by varying the number of scaffold layers, allowing the possibility of tuning the constructs physical dimensions, shape and tensile properties to suit specific targeted vascular locations.

Rolling the human amnion to engineer laminated vascular tissues

The prevalence of cardiovascular disease and the limited availability of suitable autologous transplant vessels for coronary and peripheral bypass surgeries is a significant clinical problem. A great deal of progress has been made over recent years to develop biodegradable materials with the potential to remodel and regenerate vascular tissues. However, the creation of functional biological scaffolds capable of withstanding vascular stress within a clinically relevant time frame has proved to be a challenging proposition. As an alternative approach, we report the use of a multilaminate rolling approach using the human amnion to generate a tubular construct for blood vessel regeneration. The human amniotic membrane was decellularized by agitation in 0.03% (w/v) sodium dodecyl sulfate to generate an immune compliant material. The adhesion of human umbilical vein endothelial cells (EC) and human vascular smooth muscle cells (SMC) was assessed to determine initial binding and biocompatibility (monocultures). Extended cultures were either assessed as flat membranes, or rolled to form concentric multilayered conduits. Results showed positive EC adhesion and a progressive repopulation by SMC. Functional changes in SMC gene expression and the constructs' bulk mechanical properties were concomitant with vessel remodeling as assessed over a 40-day culture period. A significant advantage with this approach is the ability to rapidly produce a cell-dense construct with an extracellular matrix similar in architecture and composition to natural vessels. The capacity to control physical parameters such as vessel diameter, wall thickness, shape, and length are critical to match vessel compliance and tailor vessel specifications to distinct anatomical locations. As such, this approach opens new avenues in a range of tissue regenerative applications that may have a much wider clinical impact.

Comparison of decellularization techniques for preparation of extracellular matrix scaffolds derived from three-dimensional cell culture

Extracellular matrix (ECM) scaffolds derived from cultured cells have drawn increasing attention for use in tissue engineering. We have developed a method to prepare cultured cell-derived ECM scaffolds by combining three-dimensional cell culture, decellularization, and selective template removal. Cell-ECM-template complexes were first formed by culture of cells in a poly(lactic-co-glycolic acid) (PLGA) mesh template to deposit their own ECM. The complexes were subsequently decellularized to remove cellular components. Finally, the PLGA template was selectively removed to obtain the ECM scaffolds. Seven decellularization methods were compared for their decellularization effects during scaffold preparation. They were: freeze-thaw cycling (-80°C, six times) with ammonia water (25 mM); 0.1% Triton™ X-100 (TX100) with 1.5M KCl aqueous solution; freeze-thaw cycling alone; ammonia water alone; TX100 extraction; osmotic shock with 1.5M KCl; and freeze-thaw cycling with 3M NaCl. Among these methods, the methods of freeze-thaw cycling with NH(4) OH and TX100 with 1.5M KCl showed the best effect on the removal of cellular components from the complexes, while the other five methods could only partially remove cellular components. The ECM scaffolds prepared by these two methods had similar gross appearances and microstructures. In vivo implantation of the ECM scaffolds prepared by these two methods induced mild host responses. The two decellularization methods were demonstrated to be effective for preparation of cultured cell-derived ECM scaffolds.

Amniotic membrane: from structure and functions to clinical applications

Amniotic membrane (AM) or amnion is a thin membrane on the inner side of the fetal placenta; it completely surrounds the embryo and delimits the amniotic cavity, which is filled by amniotic liquid. In recent years, the structure and function of the amnion have been investigated, particularly the pluripotent properties of AM cells, which are an attractive source for tissue transplantation. AM has anti-inflammatory, anti-bacterial, anti-viral and immunological characteristics, as well as anti-angiogenic and pro-apoptotic features. AM is a promoter of epithelialization and is a non-tumorigenic tissue and its use has no ethical problems. Because of its attractive properties, AM has been applied in several surgical procedures related to ocular surface reconstruction and the genito-urinary tract, skin, head and neck, among others. So far, the best known and most auspicious applications of AM are ocular surface reconstruction, skin applications and tissue engineering. However, AM can also be applied in oncology. In this area, AM can prevent the delivery of nutrients and oxygen to cancer cells and consequently interfere with tumour angiogenesis, growth and metastasis.

Tissue engineering a fetal membrane

The aim of this study was to construct an artificial fetal membrane (FM) by combination of human amniotic epithelial stem cells (hAESCs) and a mechanically enhanced collagen scaffold containing encapsulated human amniotic stromal fibroblasts (hASFs). Such a tissue-engineered FM may have the potential to plug structural defects in the amniotic sac after antenatal interventions, or to prevent preterm premature rupture of the FM. The hAESCs and hASFs were isolated from human fetal amniotic membrane (AM). Magnetic cell sorting was used to enrich the hAESCs by positive ATP-binding cassette G2 selection. We investigated the use of a laminin/fibronectin (1:1)-coated compressed collagen gel as a novel scaffold to support the growth of hAESCs. A type I collagen gel was dehydrated to form a material mimicking the mechanical properties and ultra-structure of human AM. hAESCs successfully adhered to and formed a monolayer upon the biomimetic collagen scaffold. The resulting artificial membrane shared a high degree of similarity in cell morphology, protein expression profiles, and structure to normal fetal AM. This study provides the first line of evidence that a compacted collagen gel containing hASFs could adequately support hAESCs adhesion and differentiation to a degree that is comparable to the normal human fetal AM in terms of structure and maintenance of cell phenotype.

Generation of an osteogenic graft from human placenta and placenta-derived mesenchymal stem cells

The objective of the study was to determine the feasibility of generating a biodegradable, stem cell-loaded osteogenic composite graft from human placenta. Initially, a scaffold from human chorion membrane was produced. Human placenta mesenchymal stem cells (MSCs) derived from either first-trimester chorionic villi or term chorion membrane were differentiated osteogenically on this scaffold. Outgrowth, adherence, and osteogenic differentiation of cells were assessed by immunohistochemistry (IHC), scanning electron microscopy, protein expression, and real-time polymerase chain reaction (RT-PCR). Our results showed that a cell-free extracellular matrix scaffold can be generated from human chorion. Seeded MSCs densely adhered to that scaffold and were osteogenically differentiated. Calcium and alkaline phosphatase were detected in the cell-scaffold constructs as a proof of mineralization and findings were confirmed by IHC and RT-PCR results. This study shows for the first time that generation of an osteogenic composite graft using placental tissue is feasible. It might allow therapeutic application of autologous or allogeneic grafts in congenital skeletal defects by means of a composite graft.

Fetal mesenchymal stem cells: isolation, properties and potential use in perinatology and regenerative medicine

The fetus is a source of nonembryonic stem cells (SC), with potential applications in perinatal medicine. Cells derived from the placenta, membranes, amniotic fluid or fetal tissues are higher in number, expansion potential and differentiation abilities compared with SC from adult tissues. Although some obstacles keep SC biology at distance from clinical application, the feasibility of using (homologous) SC for tissue engineering for the fetus with a congenital birth defect has been demonstrated. Also, other pathologies may benefit from SC technology.

Fetal spina bifida repair--current trends and prospects of intrauterine neurosurgery

Myelomeningocele is a common dysraphic defect leading to severe impairment throughout the patient's lifetime. Although surgical closure of this anomaly is usually performed in the early postnatal period, an estimated 330 cases of intrauterine repair have been performed in a few specialized centers worldwide. It was hoped prenatal intervention would improve the prognosis of affected patients, and preliminary findings suggest a reduced incidence of shunt-dependent hydrocephalus, as well as an improvement in hindbrain herniation. However, the expectations for improved neurological outcome have not been fulfilled and not all patients benefit from fetal surgery in the same way. Therefore, a multicenter randomized controlled trial was initiated in the USA to compare intrauterine with conventional postnatal care, in order to establish the procedure-related benefits and risks. The primary study endpoints include the need for shunt at 1 year of age, and fetal and infant mortality. No data from the trial will be published before the final analysis has been completed in 2008, and until then, the number of centers offering intrauterine MMC repair in the USA is limited to 3 in order to prevent the uncontrolled proliferation of new centers offering this procedure. In future, refined, risk-reduced surgical techniques and new treatment options for preterm labor and preterm rupture of the membranes are likely to reduce associated maternal and fetal risks and improve outcome, but further research will be needed.

Fetoscopic closure of punctured fetal membranes with acellular human amnion plugs in a rabbit model

OBJECTIVE

To explore a surgical plug formed from decellularized term human amnion membrane for fetoscopic closure of iatrogenic defects in fetal membranes in a rabbit model.

METHODS

The study was performed in eight rabbit does. Punctures were created at midgestational day 23 by 14-gauge needle fetoscopy on surgically exposed rabbit amniotic sacs. The entry sites were fetoscopically plugged either with decellularized term human amnion membrane (n=10) or previously successful commercial collagen matrix foil (n=10), followed by their primary fixation with fibrin glue and myometrial suturing. Seven punctured sacs without any plugging and 31 sacs without any manipulation served as two reference groups. Amniotic integrity and fetal parameters were assessed at gestational day 30.

RESULTS

We established a facile method to prepare sheets of decellularized term human amnion membrane and verified its nontoxicity and cell compatibility in vitro. Decellularized term human amnion membrane sheets could be delivered precisely and controlled by fetoscopy as compact plugs into amniotic defects. The surgical handling characteristics of decellularized term human amnion membrane were better than the commercial collagen matrix foil. Treatment with human decellularized term human amnion membrane was comparable to treatment with the collagen matrix with regard to efficiency in restoring amniotic integrity. Seventy-five percent and 71.4% of amniotic sacs treated with decellularized term human amnion membrane or the commercial collagen matrix foil, respectively, showed amniotic integrity, compared with 25% in the left-open study group. Histology at the 1 week experimental endpoint showed no evidence for inflammation or beginning of anatomic healing of grafted, decellularized term human amnion membrane.

CONCLUSION

Fetoscopic delivery of plugs made of decellularized term human amnion membrane presents a potentially practical surgical method to restore amniotic integrity of punctured fetal membranes.

LEVEL OF EVIDENCE

III.

Enhancing sealing of fetal membrane defects using tissue engineered native amniotic scaffolds in the rabbit model

OBJECTIVE

The purpose of this study was to compare the efficacy of native engineered amniotic scaffolds (AS) and polyesterurethane scaffolds (DegraPol) and document wound healing response when sealing iatrogenic fetal membrane defects in the rabbit model.

STUDY DESIGN

Native AS were engineered from freshly harvested membranes of 23 days' gestational age (GA; term = 31-2 d). Acellularity of AS was assessed by histology, light and scanning electron microscopy. Fetal membrane defects were created by 14 gauge-needle puncture at GA 23 days and primarily closed with AS (n = 10) or DegraPol (n = 10) or left unclosed (positive controls; n = 10). Sixty-one sacs served as negative controls. At GA 30 days a second look hysterotomy was performed to assess presence of amniotic fluid (AF) and harvest plugging sites for microscopic evaluation.

RESULTS

Engineered AS had a cell-free collagenous fiber network. AF was significantly higher only in the DegraPol group (78%; P < .05) compared to the AF in positive controls (17%). Integration of plugs in the fetal membrane defect was better with AS than DegraPol, with higher reepithelialization rates (AS: 52.5% +/- 6.5%; DegraPol: 11.6% +/- 2.6%; P < .001) and proliferation indices (AS: 0.47 +/- 0.03; DegraPol: 0.28 +/- 0.04; P = .001). In both treatment groups, cell proliferation in the myometrium was increased (P < .05).

CONCLUSION

Native AS seal iatrogenic fetal membrane defects better than DegraPol. Within a week, there is abundant reepithelilization and minimal local inflammation. This yields the proof of principle that engineered native, amniotic membrane scaffolds enhance fetal membrane wound healing response.

Fetoscopic surgery: encouraged by clinical experience and boosted by instrument innovation

Today, modern ultrasound equipment and the wide implementation of screening programmes allow the timely diagnosis of many congenital anomalies. For some of these, fetal surgery may be a life-saving option. In Europe, open fetal surgery became poorly accepted because of its invasiveness and the high incidence of postoperative premature labour and rupture of the fetal membranes. In the 1990s, the merger of fetoscopy and advanced video-endoscopic surgery formed the basis for endoscopic fetal surgery. We review the current applications of fetal surgery via both methods of access. The first clinical fetoscopic surgeries were interventions on the umbilical cord and the placenta, often referred to as obstetrical endoscopy. The outcome of a randomized clinical trial demonstrating that fetoscopic laser coagulation of chorionic plate vessels is the most effective treatment for twin-twin transfusion syndrome (TTTS) has revived interest in endoscopic fetal therapy. Operating on the fetus is another more challenging enterprise. Clinical fetal surgery programmes were virtually non-existent in Europe until minimally invasive fetoscopic surgery made such operations clinically possible as well as maternally acceptable. At present, most experience has been gathered with fetal tracheal occlusion as a therapy for severe congenital diaphragmatic hernia. As in other fields, minimally invasive surgery has pushed back boundaries and now allows safe operations to be performed on the fetal patient. Whereas minimal access seems to solve the problem of preterm labour, all procedures remain invasive, and carry a risk to the mother and a substantial risk of preterm prelabour rupture of the membranes (PPROM). The latter problem may prove to be a bottleneck for further developments, although treatment modalities are currently being evaluated.