Distribution and characterization of anionic sites in the basal lamina of developing human amniotic epithelium

Combination of natural scaffolds and conditional medium to induce the differentiation of adipose-derived mesenchymal stem cells into keratocyte-like cells and its safety evaluation in the animal cornea

Keratocytes are the main cellular components of the corneal stroma. This cell is quiescent and cannot be cultured easily. The aim of this study was to investigate differentiate human adipose mesenchymal stem cells (hADSCs) into corneal keratocyte cells by combining natural scaffolds and conditioned medium (CM) and evaluating their safety in the rabbit's cornea. Keratocytes were cultured in an optimal culture medium and this medium was collected and kept as a CM. hADSCs were cultured on the decellularized human small incision lenticule extraction (SMILE) lenticule (SL), amniotic membrane (AM), and collagen-coated plates, and were exposed to keratocyte-CM (KCM) for 7, 14, and 21 days. Differentiation was evaluated using Real-time PCR and immunocytochemistry (ICC). hADSCs were cultured on the SL scaffolds and implanted in the corneal stroma of 8 New Zealand male rabbits. Rabbits were followed for 3 months and the safety was evaluated by clinical and histological variables. Real-time PCR results showed a significant increase in the expression of keratocyte-specific markers on the 21 day of differentiation compared to the control group. ICC also confirmed the induction of differentiation. Implantation of SLs containing differentiated cells in the cornea of animals showed no serious complications including neovascularization, corneal opacity, inflammation, or signs of tissue rejection. Furthermore, the evaluation of the presence of keratocyte-like cells after three months in the rabbit stroma was confirmed by Real-time PCR and immunohistochemistry (IHC) analysis. Our results showed that combination of combination of corneal extracellular matrix and KCM can induced keratocytes differentiation of hADSC and can be introduced as a alternative method to supply the required keratocytes in corneal tissue engineering.

Amniotic membrane application in surgical treatment of conjunctival tumors

The amniotic membrane (AM) has special properties, making it ideal for clinical applications in various surgical fields like ophthalmology. It is used more frequently to cover conjunctival and corneal defects. In our retrospective study we have been combined 68 patients with epibulbar conjunctival tumors they have been surgically treated in the period of 2011-2021. Seven (10.3%) patients have been treated with AM application after surgical removal of the tumor. 54 (79%) cases were malignant, and 14 (21%) were benign. In the analyzed dataset the males had just slightly higher chance of malignancy than females, 80% versus 78.3%. For the significancy calculation the Fisher exact test was used and the result proved no significancy (p = 0.99). Six patients with AM application were malignant. The observed difference in the number of quadrants of the bulbar conjunctiva infiltrated versus significant malignancy with p = 0.050 calculated by Fisher Exact test and with p = 0.023 calculated by Likelihood-ratio test. The results of our study indicate that AM grafts are an effective alternative to cover defects after removal of epibulbar lesions due to their anti-inflammatory properties because the conjunctiva must be preserved, and especially the most important application is in malignant epibulbar conjunctival tumors.

Update review on five top clinical applications of human amniotic membrane in regenerative medicine

Due to the increasing number of studies performed in the field of regenerative medicine during the last two decades, more analytic studies are still needed to clarify the future prospect of this area of science. The main aim of this research was to review the clinical applications of human Amniotic membrane in the field of regenerative medicine critically. Furthermore, in the light of increasing numbers of available products derived from amniotic membrane, we aimed look in depth to see whether regenerative medicine research strategies have a place in the clinical setting. More specifically, in the present study, we attempted to provide insight on developing the new indication for more research and in the next step, for market leaders companies to expand cost-effectiveness of new derived AM products. 20 companies or distributers have offered some commercial products in this field. Survey on more than 90 clinical trials in last five years showed dermatology (and more specific wound healing), orthopedic, and ophthalmology are heavily biased toward multibillion dollar industry. Moreover, urology and dentistry with fewer numbers of clinical data in comparison with the above-mentioned areas, currently are in the path of translation (especially dentistry). In addition, otolaryngology and oncology with the lowest number showed more potential of research thorough understanding the properties that will help guiding the use of AM-derived products in these two areas in future. More than 50% of clinical studies were done or are developing in USA, which have the biggest share in market products. Subsequently, China, Egypt, India, Iran, and Germany with the ongoing clinical trials in different phases may have more approved products in near future.

How preparation and preservation procedures affect the properties of amniotic membrane? How safe are the procedures?

Human amniotic membrane (AM) has been widely used for tissue engineering and regenerative medicine applications. AM has many favorable characteristics such as high biocompatibility, antibacterial activity, anti-scarring property, immunomodulatory effects, anti-cancer behavior and contains several growth factors that make it an excellent natural candidate for wound healing. To date, various methods have been developed to prepare, preserve, cross-link and sterilize the AM. These methods remarkably affect the morphological, physico-chemical and biological properties of AM. Optimization of an effective and safe method for preparation and preservation of AM for a specific application is critical. In this review, the isolation, different methods of preparation, preservation, cross-linking and sterilization as well as their effects on properties of AM are well discussed. For each section, at least one effective and safe protocol is described in detail.

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.

Expression and distribution of tight junction proteins in human amnion during late pregnancy

Amnion is the innermost layer of the fetal membrane and has been suggested to regulate the volume of amniotic fluid via the amniotic epithelium. The transepithelial pathway is generally restricted by tight junctions (TJs). Thus far, human amniotic TJs have not been identified. In this study, we determined whether the human amniotic epithelium contains TJs. Reverse transcription polymerase chain reaction (RT-PCR) and western blotting analyses showed that the human amniotic epithelium has TJ components, such as occludin, ZO-1, and at least 2 types of claudins, i.e., claudin-4 and claudin-7. The TJ components were found to localize in the lateral membranes and cytoplasm at 35 weeks of gestation; these components disappeared from the lateral membrane at 37 weeks of gestation. Organ culturing of the amnion at 37 weeks gestation induced the relocalization of the TJ proteins from the cytoplasm to the lateral membranes. Furthermore, in cultured amniotic epithelial cells, dexamethasone induced the downregulation of the protein expression of TJs. These findings suggest that the human amniotic epithelium has TJs that disrupt during late pregnancy. The disruption may be induced by several factors such as glucocorticoids present in the amniotic fluid during late pregnancy.

The potential of amniotic membrane/amnion-derived cells for regeneration of various tissues

Regenerative medicine is a new field based on the use of stem cells to generate biological substitutes and improve tissue functions, restoring damaged tissue with high proliferability and differentiability. It is of interest as a potential alternative to complicated tissue/organ transplantation. Recently, amnion-derived cells have been reported to have multipotent differentiation ability, and these cells have attracted attention as a cell source for cell-transplantation therapy. The amnion possesses considerable advantageous characteristics: the isolated cells can differentiate into all three germ layers; they have low immunogenicity and anti-inflammatory functions; and they do not require the sacrifice of human embryos for their isolation, thus avoiding the current controversies associated with the use of human embryonic stem cells. Moreover, we developed human amniotic cell-sheets using a novel culture surface coated with a noncytotoxic, temperature-responsive elastic protein-based polymer. We also generated a "hyper-dry-amnion", which has already been applied clinically in the ophthalmological field. Compared to cryopreserved fresh amnion, "hyper-dry-amnion" is easy to handle and has started to bring good results to patients. These materials from the amnion are also expected to open a new field in tissue engineering. Thus, amnion, which had been discarded after parturition, has started to be appreciated as an attractive material in the field of regenerative medicine. In this review, the most recent and relevant clinical and experimental data about the use of amniotic membrane and cells derived from it are described.

Ultrastructure of the materno-embryonic interface in the first trimester of pregnancy

During early pregnancy, the absence of fully developed internal organs means that the embryo is dependent on highly differentiated adnexal structures such as the secondary yolk sac and free-floating amniotic membrane as well as the placental trophoblast. In this review, we describe and illustrate the ultrastructural characteristics of these different cellular barriers which separate maternal and embryonic tissues during the first trimester of pregnancy. Samples of chorionic plate, umbilical cord, secondary yolk sac and amniotic membrane have been obtained from intact gestational sacs of pregnancies between 6 and 11 weeks and examined at the ultrastructural level. Features indicating intense biosynthetic activity were found in the syncytiotrophoblast of the chorionic plate, the endoderm of the secondary yolk sac and mesenchymal cells of the amniotic membrane. Barriers in the form of a well-developed basal lamina were present between the trophoblast and mesenchyme of the chorionic plate and beneath the epithelium of the amniotic membrane and umbilical cord, but were incomplete between the mesenchymal tissues of the yolk sac and mesothelial and endodermal layers, and also around the capillaries of the chorionic plate. Basement membrane thickening and interactions with the underlying stroma were observed with increasing gestational age in connection with amniotic epithelial differentiation and development of basal foot processes. After 9 weeks, the yolk sac showed a marked degeneration of surface cells, accompanied by increased fibrosis of the mesenchyme. These findings are discussed with reference to the biological functions of the adnexal structures in the development of the growing embryo, and their possible role is assessed in the physiology of exchange during the first trimester of pregnancy.

Morphologic changes in the human amnion epithelium that accompany labor as seen with scanning and transmission electron microscopy

Scanning and transmission electron microscopy were used to assess the influence of normal, active labor on the ultrastructure of the human amnion epithelial membrane. Amnion membranes (reflected and placental portions) were obtained from patients either in active labor who were delivered vaginally or by cesarean section after 6 to 12 hours of labor or from patients who underwent elective cesarean section before clinical signs of overt labor. Scanning electron microscopy revealed that reflected amnion membranes that were obtained from patients who were not in labor consisted of a uniform single layer of epithelial cells with numerous microvilli on the apical surface and closely associated cellular borders. In contrast, amnion membranes that were obtained from patients who were in labor consisted of a single layer of epithelial cells, which was interrupted by wide intercellular gaps and extracellular extrusions. Transmission electron microscopy showed that intercellular junctions tended to be less complex in patients who were in labor versus patients who were not in labor. Although lipid droplets were prevalent in both patient groups, specimens that were obtained from patients who were in labor had more lipid droplets per cell than specimens from patients who were not in labor. These results support the theory that the complex biochemical events that culminate in parturition are accompanied and/or preceded by demonstrable morphologic changes in the amnion membrane.

Cytochemical characterization of cuprolinic blue-stained proteoglycans in the epithelial-stromal interface of the guinea pig lateral prostate

Three types (T1, T2, T3) of proteoglycan (PG) filaments, as demonstrated by cuprolinic blue (CB) under critical electrolyte concentration method in the epithelial-stromal interface of the guinea pig lateral prostate, were characterized cytochemically by using a number of glycosaminoglycan(GAG)-degrading enzymes and nitrous acid. The results showed that T1 filaments located in basement membranes of the epithelium, endothelium, and smooth muscle cells, were removed by nitrous acid, heparitinase, and pronase but resistant to chondroitinase (Ch)-ABC and Ch-AC, heparinase, neuraminidase, and Streptomyces (S) hyaluronidase. The T1 filaments, therefore, contain heparan sulfate. The T2 filaments closely linked to collagen fibrils were removed by Ch-ABC, Ch-ABC plus S-hyaluronidase, and pronase but were resistant to nitrous acid, heparitinase, heparinase, neuraminidase, and S-hyaluronidase. These show that T2 filaments are rich in dermatan sulfate. The T3 filaments in the interstitial spaces and on the surface of fibroblasts were removed by Ch-ABC, Ch-AC, and pronase but were resistant to heparitinase, heparinase, hyaluronidase, neuraminidase, and nitrous acid. They are, therefore, rich in chondroitin sulfate.

Modification of anionic sites in myocardial capillary basal laminae of diabetic rats

Capillary basal laminar thickening is a distinctive feature of diabetic microangiopathy; however, the mechanism responsible for this abnormality remains to be clarified. Recent reports have described a reduction in the distribution of anionic sites in diabetic glomerular basement membranes, with the suggestion that this reduction may generate a compensatory synthesis of basal laminar constituents, causing laminar thickening. In order to provide additional information, the character and distribution of the basal laminar anionic profile were examined in the myocardium of diabetic rats. Diabetes mellitus was induced in 14 rats by injection with streptozotocin, ip; 6 rats served as controls. Myocardial tissue was subjected to Charonis' procedure for the demonstration of anionic sites with the cationic electron-dense dye, ruthenium red, following the sacrifice of the animals at intervals up to 11 months after the induction of the diabetes. The tissues were then processed routinely for electron microscopic examination. A total of 20 electron micrographs, at magnifications of 13,000x and 33,000x, were obtained from each rat for the quantitation of anionic sites. A length measuring 6 micron along each basal lamina was utilized for determining the number of anionic loci. Results of this study show that (1) the number and size of anionic sites in myocardial basal laminae is reduced in diabetic rats, (2) this decrease becomes more pronounced with prolongation of the diabetes, (3) it is detectable prior to the demonstration of basal laminar thickening by electron microscopy, and (4) enzyme digestion treatments indicated that heparan sulfate proteoglycan is the essential stainable component of the anionic sites. These findings provide evidence that the laminar anionic profile is altered in the diabetic myocardium and support the view that this abnormality constitutes a significant initial event in the pathogenesis of basal laminar thickening.

Cell-cell matrix interactions in induced lung injury: III. Long term effects of X-irradiation on basal laminar proteoglycans

The lungs of male LAF1 mice were locally irradiated with doses of 5, 9, and 13 Gy. The animals were killed at times corresponding to the appearance of histologically identifiable fibrosis or, for 13 Gy, at the LD50 for these doses and strain of mouse: 63, 36, and 28 weeks postirradiation (PI) respectively. Lungs were excised, incubated in buffer alone, or partially digested with enzymes for determination of relative glycosidase resistance, fixed with ruthenium red/Triton X-100 for demonstration of basal laminar anionic sites, and processed for electron microscopy. Sham-irradiated and untreated control groups (0 Gy, 0 times) were also processed. Tissue was examined ultrastructurally and alterations in both alveolar and capillary basal laminar anionic sites were quantitated. In each of the doses examined the number of anionic sites surpassed normal levels; however, the glycosidase resistance of the regenerated laminae at these late time points was not significantly altered from controls. This contrasts with the marked increase in the glycosidase resistance of laminae regenerating from radiation damage (4-12 weeks PI) reported earlier. The increased numbers of anionic sites were compared to expected values derived from models based on compensatory synthesis and continued accumulation and indicate close correlation with certain aspects of the compensatory synthesis model but not with others. The effects on basal laminar permeability, basal laminar thickening, and fibrotic induction are discussed.