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Role of growth factors for ocular surface reconstruction after amniotic membrane transplantation

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... %99 su, inorganik ve organik maddelerden, tuzlardan ve fetustan dökülen epitel hücrelerden oluşur. Organik bileşiklerin yarısı protein diğer yarısı da karbonhidrat, yağ, enzim, hormon ve pigmentlerden ibarettir (25,(29)(30)(31). ...
... Böylece kollajen sentezine katkıda bulunarak anjiyogenezis sayesinde ağrı ve enflamasyonu azaltıcı etki gösterirler. Ayrıca kolay ve çabuk elde edilebilen ve değeri giderek artan biyolojik bir üründür (30,(32)(33)(34)(35)(36)(37)(38)(39)(40)(41). ...
... Korneada oluşan alkali yanıkların kornea ve konjunktiva epitelinde meydana getirdiği hasarlar kalıcı defektlere yol açabilir. Kornea ve konjunktivada oluşan hasarların ilk dönemlerinde amniyon sıvısının kullanılması inflamasyon ve hasarı azaltmasının yanında epitelizasyonu hızlandırır, simblefaron oluşumunu engeller, limbal kök hücre hasarı ve damarlaşmayı azaltır, miyofibroblastların fibroblastlara dönüşümünü azaltarak nedbe dokusu oluşumunu engeller (17,22,25,29,40,41,43,44). Amniyon sıvısının içerisinde bulunan çok sayıda büyüme faktörü bu etkinliği göstermesinin sebebidir (25,28,30,35). Bu çalışmada da amniyon sıvısının alkali kornea yanıkları üzerindeki etkinliğini klinik ve histopatolojik bulgular ışığında değerlendirmek amaçlandı. ...
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Korneadaki epitel bütünlüğünün bozulması mikroorganizmaların kornea epitelini rahat bir şekilde geçmesine ve korneal ülserasyonlara sebep olabilir. Korneada oluşan alkali yanıklar kornea epitel bütünlüğünü bozarak ülserasyonlara hatta perforasyonlara sebep olabilir. Alkali kornea yanıklarının tedavisi için çok sayıda medikal tedavi seçeneği bulunmaktadır. Bu çalışmada korneanın alkali yanıkları üzerine amniyon sıvısının etkinliğinin klinik ve histopatolojik sonuçlarının araştırılması amaçlandı. Amniyon sıvısı içerisinde büyüme faktörleri ile IL-1α ve IL-1β ekspresyonunu baskılayarak inflamasyonu azaltan faktörlerin bulunması çalışmanın hipotezinin kurulmasında önemli bir dayanak oluşturdu. Çalışmada 30 adet dişi cinsiyete sahip, Wistar Albino ırkı rat kullanıldı. Ratlar rastgele 3 gruba ayrıldı. Alkali yanık oluşturmak amacıyla ratların sağ gözlerinde kornea üzerinde 2N yoğunluğunda NaOH solüsyonu 40 saniye bekletildi. Birinci gruptaki (AS) ratlarda alkali kornea yanığı oluşturulup 20 gün boyunca günde üç kez ikişer damla sığır amniyon sıvısı göze damlatıldı. İkinci gruptaki (PK) ratlarda alkali kornea yanığı oluşturulup 20 gün boyunca üç kez ikişer damla serum fizyolojik uygulandı. Üçüncü gruptaki (NK) ratlarda alkali kornea yanığı oluşturulmayıp 20 gün boyunca günde üç kez ikişer damla sığır amniyotik sıvısı göze damlatıldı. Çalışma boyunca klinik bulgular indirekt oftalmoskop, fluorescein testi ve Rose Bengal testi ile değerlendirildi. Çalışma sonunda ise, kornea epitelindeki değişiklikleri değerlendirmek için histopatolojik değerlendirmeler yapıldı. Klinik değerlendirmeler sonucunda amniyon sıvısı uygulanan gruptaki (AS) ratlarda deneysel alkali yanığın neden olduğu korneal hasar, konjunktivitis, blefarospazm ve fotofobi gibi klinik belirtilerin hafiflediği tespit edilmiştir. Serum fizyolojik uygulanan ikinci gruptaki (PK) ratlarda ise, korneal perforasyon, şiddetli konjunktivitis, blefarospazm ve fotofobi oluştuğu tespit edildi. Histopatolojik incelemeler sonucunda, ödem ve neovaskülarizasyon şiddeti açısından PK ve AS grupları arasında istatistiksel olarak anlamlı farkın olduğu tespit edildi (P<0.05). Sonuç olarak amniyon sıvısının kornea alkali yanıklarında etkili olduğu, medikal ya da operatif tedaviye ek olarak kullanılmasının yararlı olacağı kanısına varılmıştır. Disruption of the epithelial integrity of the cornea may cause microorganisms to pass easily through the corneal epithelium and cause corneal ulcerations. Alkaline burns in the cornea may disrupt the integrity of the corneal epithelium and cause ulcerations or even perforations. There are many medical treatment options for the treatment of alkaline corneal burns. One of these medical treatment options is amniotic membrane and amniotic fluid. In this study, it was aimed to investigate the effectiveness of amniotic fluid on alkaline burns of the cornea. Thirty Wistar Albino rats were used in the study. Rats were randomly divided into 3 groups. In order to cause an alkaline burn, a filter paper absorbed with 2N NaOH solution was kept on the cornea of the right eyes of the rats for 40 seconds. Alkaline corneal burn was created in rats in the first group and two drops of bovine amniotic fluid were dripped into the eye three times a day for 20 days. In the second group, an alkaline corneal burn was created and two drops of saline was instilled into the eye three times a day for 20 days. In the third group, no alkaline corneal burn was created and two drops of bovine amniotic fluid were dripped into the eye three times a day for 20 days. Throughout the study, clinical findings were evaluated by indirect ophthalmoscope, fluorocein test and Rose Bengal test. At the end of the study, histopathological evaluations were made to evaluate the changes in the corneal epithelium. As a result of the clinical evaluations, it was found that corneal damage, conjunctivitis, blepharospasm and photophobia were reduced in the rats in the amniotic fluid group. Corneal perforation, severe conjunctivitis, blepharospasm and photophobia were found in rats in the second group. As a result of histopathological examinations, a statistically significant difference was found between the PK and AS groups in terms of the severity of edema and neovascularization (P<0.05). As a result, it was concluded that amniotic fluid is effective in corneal alkalnei burns and it would be beneficial to use it in addition to medical or operative treatments.
... 34 35 The AM is also capable of binding growth factors which may help to promote wound healing. [36][37][38][39] However, these characteristics of AM may not fully explain why AM graft prevents pterygium recurrence. For example, it has been shown that a supernatant of homogenised AM promotes rather than inhibits proliferation of conjunctival fibroblasts. ...
... For example, it has been shown that a supernatant of homogenised AM promotes rather than inhibits proliferation of conjunctival fibroblasts. 38 In addition, factors contained in AM may also change after preservation. It has been reported that after preservation at −80°C for one month, activities of transforming growth factor (TGF ) 1 and 2, basic fibroblast growth factor (bFGF), and hepatocyte growth factor (HGF) in AM decreases by 50%. ...
... It has been reported that after preservation at −80°C for one month, activities of transforming growth factor (TGF ) 1 and 2, basic fibroblast growth factor (bFGF), and hepatocyte growth factor (HGF) in AM decreases by 50%. 38 However, recent finding indicated that preserved AM suppresses the expression of TGF -I, TGF -II, TGF -III, TGF receptor type II, and myofibroblast differentiation in corneal and limbal fibroblasts. 14 Likewise, preserved AM also suppresses the signalling pathway of TGF , CD-44, -1 integrin, and FGFR1/flg of pterygium fibroblasts. ...
Article
AIM To study the efficacy and safety of amniotic membrane graft as an adjunctive therapy after removal of primary pterygium, and to compare the clinical outcome with conjunctival autograft and topical mitomycin C. METHODS 80 eyes of 71 patients with primary pterygia were treated with excision followed by amniotic membrane graft. The result was compared retrospectively with 56 eyes of 50 patients receiving conjunctival autograft, and 54 eyes of 46 patients receiving topical mitomycin C. Patients were followed for at least 6 months, and the averaged follow up periods for the three groups were 13.8, 22.8, and 18.4 months, respectively. RESULTS There were three recurrences (3.8%) in the amniotic membrane graft group, three recurrences (5.4%) in the conjunctival autograft group, and two recurrences (3.7%) in the topical mitomycin C group. There was no significant difference in recurrence rate among the three groups (p = 0.879). No major complications occurred in the amniotic membrane graft group or the conjunctival autograft group. One case of infectious scleritis due to scleral ischaemia occurred in the topical mitomycin C group. CONCLUSION This study showed that amniotic membrane graft was as effective as conjunctival autograft and mitomycin C in preventing pterygium recurrence, and can be considered as a preferred grafting procedure for primary pterygium.
... 34 35 The AM is also capable of binding growth factors which may help to promote wound healing. [36][37][38][39] However, these characteristics of AM may not fully explain why AM graft prevents pterygium recurrence. For example, it has been shown that a supernatant of homogenised AM promotes rather than inhibits proliferation of conjunctival fibroblasts. ...
... For example, it has been shown that a supernatant of homogenised AM promotes rather than inhibits proliferation of conjunctival fibroblasts. 38 In addition, factors contained in AM may also change after preservation. It has been reported that after preservation at −80°C for one month, activities of transforming growth factor (TGF ) 1 and 2, basic fibroblast growth factor (bFGF), and hepatocyte growth factor (HGF) in AM decreases by 50%. ...
... It has been reported that after preservation at −80°C for one month, activities of transforming growth factor (TGF ) 1 and 2, basic fibroblast growth factor (bFGF), and hepatocyte growth factor (HGF) in AM decreases by 50%. 38 However, recent finding indicated that preserved AM suppresses the expression of TGF -I, TGF -II, TGF -III, TGF receptor type II, and myofibroblast differentiation in corneal and limbal fibroblasts. 14 Likewise, preserved AM also suppresses the signalling pathway of TGF , CD-44, -1 integrin, and FGFR1/flg of pterygium fibroblasts. ...
Article
Full-text available
To study the efficacy and safety of amniotic membrane graft as an adjunctive therapy after removal of primary pterygium, and to compare the clinical outcome with conjunctival autograft and topical mitomycin C. 80 eyes of 71 patients with primary pterygia were treated with excision followed by amniotic membrane graft. The result was compared retrospectively with 56 eyes of 50 patients receiving conjunctival autograft, and 54 eyes of 46 patients receiving topical mitomycin C. Patients were followed for at least 6 months, and the averaged follow up periods for the three groups were 13.8, 22.8, and 18.4 months, respectively. There were three recurrences (3.8%) in the amniotic membrane graft group, three recurrences (5.4%) in the conjunctival autograft group, and two recurrences (3.7%) in the topical mitomycin C group. There was no significant difference in recurrence rate among the three groups (p = 0.879). No major complications occurred in the amniotic membrane graft group or the conjunctival autograft group. One case of infectious scleritis due to scleral ischaemia occurred in the topical mitomycin C group. This study showed that amniotic membrane graft was as effective as conjunctival autograft and mitomycin C in preventing pterygium recurrence, and can be considered as a preferred grafting procedure for primary pterygium.
... Sato, et al. [41] Analysis of AM extracts (from both fresh and preserved AM), with and without homogenized AM epithelium. ...
... Amniotic membrane itself has been shown to express epidermal growth factor, hepatocyte growth factor, and keratinocyte growth factor [41,42]. However, it seems that the cryopreservation process, by damaging AM cells [14] results in a decrease in AM-associated levels of growth factors [41,42]. ...
... Amniotic membrane itself has been shown to express epidermal growth factor, hepatocyte growth factor, and keratinocyte growth factor [41,42]. However, it seems that the cryopreservation process, by damaging AM cells [14] results in a decrease in AM-associated levels of growth factors [41,42]. Amniotic membrane also serves to induce growth factor expression in tissue that it is in contact with: Choi et al. [43] showed that an AM cover increased the expression of keratinocyte growth factor in mouse corneas with large epithelial defects to a greater degree than a bandage contact lens cover. ...
Article
Human amniotic membrane (AM) is composed of three layers: a single epithelial layer, a thick basement membrane, and an avascular stroma. Amniotic membrane has anti-adhesive properties and is felt to promote epithelialization and decrease inflammation, neovascularization, and fibrosis. Amniotic membrane transplantation (AMT) is currently being used for a continuously widening spectrum of ophthalmic indications. Amniotic membrane transplantation has been shown to be effective in the reconstruction of the corneal surface in the setting of persistent epithelial defects, sterile corneal ulcerations, and partial limbal stem cell (LSC) deficiency states, including those secondary to chemical or thermal burns. Amniotic membrane transplantation also has been used in conjunction with limbal stem cell transplantation (LSCT) both in a concurrent fashion as well as in preparation for LSCT. Amniotic membrane transplantation also has been used in place of conjunctival autografting after pterygium excision and to reconstruct the conjunctival surface after removal of conjunctival lesions. Most recently, ex vivo cultivation and expansion of limbal epithelial cells has been performed utilizing AM as a matrix. However, the superiority of AMT over other treatment modalities in many of these settings needs to be substantiated by controlled clinical trials.
... Amniotic membrane and amniotic fluid accelerate epithelization, prevent protein and fluid loss at the wound surface, increase fibroblastic activity, and reduce adhesion formation; as well as having antibacterial, antioxidant, and non-immunological effects (10)(11)(12)(13). ...
... Amniotic membrane transplantation and amniotic fluid reduce the inflammation and the effects of the injury when applied early in the course of the tissue damage and these interventions accelerate epithelization (2,5,7,8,13). Amniotic membrane and fluid show these effects via several growth factors and they display antioxidant effects (10,13). ...
... [20] Przyspieszenie nab³onkowania jest mo¿liwe dziêki czynnikom wzrostowym produkowanym przez komórki owodni, takim jak: FGF (Fibroblast growth factor), HGF (Hepatocyte growth factor), TGF -beta (Transforming growth factor). [21,22] a gynaecologist during Caesarean section, after the patient's informed consent. Before she can be qualified as an amnion donor, she has to be tested for viral infections: HIV, virus hepatitis B and C, or a syphilis-specific test. ...
... The inhibition of neutrophils by amnion cells reduces the inflammatory condition and collagen breakdown, which results in faster wound healing [20]. Acceleration of epithelialization is possible thanks to growth factors produced by amnion cells, such as FGF (fibroblast growth factor), HGF (hepatocyte growth factor), TGF-beta (transforming growth factor) [21,22]. Najczêoeciej opatrunki z owodni stosuje siê w obrêbie twarzy, gdy dodatkowo dosz³o do oparzenia oczu. ...
Article
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The aim of the study is presentation biological dressings made of human amniotic membrane. Amniotic membrane is received from sero-negative donors by Caesarean section. Use of human amniotic membrane is wide, but especially attention should be paid at: burns, eye diseases and Lyell syndrome.
... It is an ideal substrate for progenitor epithelial cell culture by prolonging their lifespan and preventing apoptosis (1) . The amnion produces transforming growth factor (TGF) that is able to promote epithelialization as well as modulate fibroblast proliferation and differentiation (2) . It does not demonstrate histocompatibility epitelializację, modulować rozmnażanie i różnicowanie fibroblastów (2) . ...
... The amnion produces transforming growth factor (TGF) that is able to promote epithelialization as well as modulate fibroblast proliferation and differentiation (2) . It does not demonstrate histocompatibility epitelializację, modulować rozmnażanie i różnicowanie fibroblastów (2) . Nie wykazuje ekspresji antygenów zgodności tkankowej, co pozwala na jej przeszczepianie bez dodatkowego stosowania immunosupresji i ryzyka odrzucenia. ...
Article
In the contemporary medicine, undifferentiated progenitor cells of various origin and various degree of plasticity have become highly promising. Their most abundant, renewable and uncontroversial sources are placental tissues and umbilical blood. The only epithelial cells in this group come from the amnion which is used as a whole as an allogenic biological dressing. They have a range of unusual properties, such as the relative lack of histocompatibility antigens, plasticity (enabling their differentiation into a number of epithelial and mesenchymal cells) and the lack of neoplastic capacity. Amniotic epithelial cells are the only epithelial cells of the placenta. It is believed that they retain their progenitor (pluripotent) properties even in term pregnancies. This probably results from the fact that they omit the differentiation that accompanies gastrulation. Such features are typical of all placental cells which differ from amniotic epithelial cells only in their non-epithelial origin. In culture conditions, amniotic epithelial cells are characterized by a considerable plasticity: they can be stimulated to differentiate into adipocytes, chondrocytes, osteocytes, myocytes, cardiomyocytes, neurocytes, pancreatic cells and hepatocytes. To date, however, the attempts to direct their development towards the epidermis have not been successful. Obtaining multilayer epidermis in amniotic epithelial culture would be of considerable importance for tissue engineering of biological dressings. Amniotic membranes have been used for this purpose for many years, but because of their complex structure and metabolic requirements, they do not heal but dry up when applied to the wound. Some reports, however, indicate that the epithelium isolated from the amnion could be able to heal thus being suitable for allogenic grafts.
... It consists of 99% water, inorganic and organic substances, salts and epithelial cells shed from the fetus. Half of the organic compounds are proteins and the other half are carbohydrates, fats, enzymes, hormones and pigments [22,23]. Amniotic fluid accelerate cell epithelialization and prevent protein and fluid loss on the wound surface, thus reducing adhesion formation, while increasing fibroblastic activity with antibacterial and nonimmunological power. ...
Article
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In this study, it was aim to examine the local application of bovine amniotic fluid on bone fracture healing in rats. Twenty female sprague dawley rats included in the study were divided into 2 groups of 10. The sham group (n=10): Bone fractures were created in the right tibia bones of the rats and fixed with kirschner wire. After a four–week recovery period, the subjects were sacrificed. Local bovine amniotic fluid group (n=10): Bone fractures were created in the right tibia bones of the rats and local bovine amniotic fuid was applied during fixation with kirschner wire. After a four–week recovery period, the subjects were sacrificed. Samples from all subjects were decalcified, stained with hematoxylin and eosin, and new bone formation and fibrosis were analyzed. When the groups were evaluated in terms of new bone regeneration, it was determined that the new bone regeneration in the subjects treated with local bovine amniotic fluid were statistically significantly higher than sham group (P<0.05). When the groups were evaluated in terms of fibrosis, the fibrosis value in the sham group was found to be statistically significantly higher when compared with the local bovine amniotic fluid group (P<0.05). It can be stated that local bovine amniotic fluid application may positively affect the healing of bone fractures.
... It has been reported that the risk of transmitted infections may decreases when preserving and sterilizing the AM by para acetic acid, gamma irradiation, and/or trehalose [39]. Different growth factors such as hepatocyte growth factor (HGF), epidermal growth factor (EGF), basic fibroblast growth factor (BFGF), transforming growth factor b (TGFb), and platelet-derived growth factor (PDGF) are secreted by the AM [41,42]. EGF is mainly found in the amniotic epithelium and is a powerful mitogen for the epithelial cells growth and its high level of expression may elucidate for the ocular surface improved wound healing [25,39]. ...
Article
Full-text available
Amniotic membrane (AM) is a biological tissue that surrounds the fetus in the mother’s womb. It has pluripotent cells, immune modulators, collagen, cytokines with anti-fibrotic and anti-inflammatory effect, matrix proteins, and growth factors. In spite of the biological characteristics, some results have been released in preventing the adhesion on traumatized surfaces. Application of the AM as a scaffold is limited due to its low biomechanical resistance and rapid biodegradation. Therefore, for using the AM during surgery, its modification by different methods such as cross-linking of the membrane collagen is necessary, because the cross-linking is an effective way to reduce the rate of biodegradation of the biological materials. In addition, their cross-linking is likely an efficient way to increase the tensile properties of the material, so that they can be easily handled or sutured. In this regard, various methods related to cross-linking of the AM subsuming the composite materials, physical cross-linking, and chemical cross-linking with the glutraldehyde, carbodiimide, genipin, aluminum sulfate, etc. are reviewed along with its advantages and disadvantages in the current work.
... These growth factors help to stimulate epithelialization and differentiation of stromal fibroblasts. [26] HAM also has reported anti-inflammatory action by suppressing the expression of inflammatory cytokines from the ocular surface. [27] Unlike HAM, the pPCL membrane lacks any intrinsic biological property but interestingly, we found that pPCL grafts were almost of similar efficacy in healing the epithelial defects in rabbit corneas despite the absence of supplemented cytokines and growth factors. ...
Article
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Purpose: To evaluate biocompatibility and safety of plasma-treated poly-ε-caprolactone (pPCL) membrane compared to the human amniotic membrane in the healing of corneal epithelial defects in an experimental model. Methods: This is a prospective, randomized animal study including 12 rabbits. Circular epithelial injury measuring 6 mm in diameter was induced over the central cornea of one eye in twelve rabbits. The rabbits were randomized into two groups; in group A, the defect was covered with human amniotic membrane, while in group B, an artificial membrane made of bio-polymer plasma-treated poly-ε-caprolactone was grafted. Six rabbits were euthanized after 1 month and the other six after 3 months and the corneal epithelium was evaluated histopathologically and with immunohistochemistry. Results: Light microscopy of the corneal tissue performed after 1 month and 3 months demonstrated similar findings with no significant complications in either group. Immunohistochemistry with anti-CK-3 antibody showed characteristic corneal phenotype in the healed epithelium. In eyes grafted with pPCL membrane, epithelial healing as estimated by a decrease in size of the defect was significantly better than the group treated with the human amniotic membrane at all time periods monitored (P < 0.05), except day 1 (P = 0.83). The percentage reduction in the size of the epithelial defect was also significantly more in the pPCL membrane group as compared to the human amniotic membrane at all time periods (P < 0.05 at all observations) post-implantation except day 1 (P = 0.73). Conclusion: Plasma-treated poly-ε-caprolactone membrane is safe, biocompatible, and effective in the healing of corneal epithelial defects in rabbits.
... As compared to the bare sclera technique, changes in astigmatism were significantly more with amniotic membrane graft and conjunctival autograft technique mainly due to better healing and less granulation tissue formation. [11,[13][14] Altan-yaycioglu et al. have used different surgical techniques: conjunctival autograft with sutures (CAG-s) or fibrin glue (CAG-g), conjunctival rational flap (CRF), or amniotic membrane transplantation with either suture (AMT-s) or with glue (AMT-g) on the postoperative astigmatism. [15] They found that changes in astigmatism were significantly related to the preoperative size of the pterygium and were not related to the type of grafting or the use of suture or glue. ...
Article
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Purpose: To study the changes in corneal astigmatism before and after pterygium excision as well as with differences between various surgical techniques (bare sclera, conjunctival autograft, amniotic membrane graft). Methods: The study population included 71 patients with primary pterygium who underwent surgery. The surgical techniques used differed among the study population. All the patients were preoperatively assessed for visual acuity, anterior and posterior segments, autorefraction, and autokeratometry. After surgery, the patients were assessed for visual acuity, autorefraction, and autokeratometry on day 5, 1 month, and 3 months and the results were analyzed. Paired and unpaired t-tests were used to compare the variables. The probability level of 0.05 was considered as statistically significant. Results: The reduction in the mean preoperative astigmatism of 3.47 ± 1.74 Diopters (D) to 1.10 ± 0.78 D 3 months after surgery was statistically significant (P < 0.0001). Bare sclera, conjunctival autograft, and amniotic membrane graft techniques exhibited changes in astigmatism amounting to 1.85 ± 0.88 D, 2.55 ± 1.26 D, and 2.67 ± 1.44 D, respectively. Pterygium excision surgeries using amniotic membrane graft and conjunctival autograft techniques were more effective than pterygium excision surgery using bare sclera technique in reducing astigmatism. Conclusion: Pterygium excision results in significant reduction in astigmatism which leads to improvement in visual acuity. Amniotic membrane graft and conjunctival autograft are better surgical techniques than bare sclera as far as reducing astigmatism is concerned.
... AM produces basic fibroblast, hepatocyte and transforming growth factor (TGF). These growth factors can stimulate epithelialization and modulate proliferation and differentiation of stromal fibroblasts (Sato, 1998). The current study was performed to describe and evaluate the effectiveness of freeze-human amniotic membrane transplantation in the treatment of experimental corneal wound in the dogs by the clinical evaluation of corneal epithelial wound healing and inspection of epithelial proliferation. ...
Article
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In our experimental study we evaluated the efficacy of human freeze-dried amniotic membrane on healing of corneal wound defect in dogs. A corneal wound was performed by using corneal trephine 8.5 mm in diameter. A total of 14 dogs were divided into two groups of 7 dogs in each: (A) Control group; (B) AM group treated by transplantation of freezedried human amniotic membrane in conjunction with a third eyelid flap. Clinical outcome was monitored by evaluation of epiphora, ocular discharge, corneal vascularization, corneal opacity and corneal epithelization at the 7th, 11th, 15th and 30th days post-surgery. Fluorescein staining was used to estimate the closure of the corneal wounds. Histopathological examination was performed in two dogs of each group; the thickness of the newly generated cornea was measured by using Image j analysis software. The control group was complicated with severe neovascularization, ocular discharge and corneal opacity. There were excessive thickness in the stroma of control group as reflect of inflammatory reaction. The AM group showed mild degree vascularization which was completely absent by the end of experiment. Corneal epithelialization was completed within 15 days after the transplantation in the AM group. In conclusion, transplantation of human amniotic membrane improves canine corneal epithelial wound healing effectively
... The unique property of amniotic membranes (AMs) in the reconstruction of ocular surfaces is that it contains amazing mixture of growth factors and cytokines, facilitating proliferation and differentiation of epithelial cells, reducing the inflammatory response by inhibiting protease activity, and reducing inflammatory cell activity. [2,3] Clinical results showed that the success rate of treatment for corneal ulcers with AMT is over 80%. [4,5] In our prospective study, we evaluated the benefit of use of commercially available dried and processed AM in the management of resistant corneal ulcers. ...
... The AM secretes several growth factors such as epidermal growth factor (EGF), hepatocyte growth factor (HGF), basic fibroblast growth factor, platelet-derived growth factor (PDGF), and transforming growth factor b (TGFb) [40,41]. EGF is a powerful mitogen for the growth of epithelial cells and its high level of expression following transplantation may explain improved wound healing of the ocular surface [23]. ...
Article
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Limbal stem cell deficiency (LSCD) can result from a variety of corneal disorders, including chemical and thermal burns, infections, and autoimmune diseases. The symptoms of LSCD may include irritation, epiphora, blepharospasms, photophobia, pain, and decreased vision. There are a number of treatment options, ranging from nonsurgical treatments for mild LSCD to various forms of surgery that involve different cell types cultured on various substrates. Ex vivo expansion of limbal epithelial cells (LEC) involves the culture of LEC harvested either from the patient, a living relative, or a cadaver on a substrate in the laboratory. Following the transfer of the cultured cell sheet onto the cornea of patients suffering from LSCD, a successful outcome can be expected in approximately three out of four patients. The phenotype of the cultured cells has proven to be a key predictor of success. The choice of culture substrate is known to affect the phenotype. Several studies have shown that amniotic membrane (AM) can be used as a substrate for expansion of LEC for subsequent transplantation in the treatment of LSCD. There is currently a debate over whether AM should be denuded (i.e., de-epithelialized) prior to LEC culture, or whether this substrate should remain intact. In addition, crosslinking of the AM has been used to increase the thermal and mechanical stability, optical transparency, and resistance to collagenase digestion of AM. In the present review, we discuss the rationale for using altered versus unaltered AM as a culture substrate for LEC. Stem Cells Translational Medicine 2018.
... In a recent study, it was proved that AM created the previous referred required healing factors. Firstly, AM maintained mucosal perfusion through the secreted transforming growth factor (TGF) which can stimulate epithelialization and modulate proliferation and differentiation of stromal fibroblasts [44]. Secondly, AM decreased gastric acidity as amniotic epithelial cells (AEC) were able to secrete albumin, which is consistent with α1antitrypsin and other hepatocyte gene expression profiles which act as a natural neutralizing agent to gastric acid [45]. ...
Article
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Background Gastric mucosal defect could result from several causative factors including the use of nonsteroidal anti-inflammatory drugs, Helicobacter pylori infection, gastrointestinal and spinal cord diseases, and neoplasia. This study was performed to achieve a novel simple, inexpensive, and effective surgical technique for the repair of gastric mucosal defect. Methods Six adult male mongrel dogs were divided into two groups (three dogs each). In the control positive group (C + ve), dogs were subjected to surgical induction of gastric mucosal defect and then treated using traditional medicinal treatment for such a condition. In the amniotic membrane (AM) group, dogs were subjected to the same operation and then fresh AM allograft was applied. Clinical, endoscopic, biochemical (serum protein and lipid and pepsin activity in gastric juice), histopathological, and immunohistochemistry evaluations were performed. Results Regarding endoscopic examination, there was no sign of inflammatory reaction around the grafted area in the AM group compared to the C + ve group. The leukocytic infiltration in the gastric ulcer was well detected in the control group and was less observed in the AM group. In the AM group, the concentrations of both protein and lipid profiles were nearly the same as those in serum samples taken preoperatively at zero time, which indicated that the AM grafting acted the same as gastric mucosa. The re-epithelization of the gastric ulcer in the C + ve group was not yet detected at 21 days, while in the AM group it was well observed covering most of the gastric ulcer. AM accelerated the re-epithelization of the gastric ulcer. The fibrous connective tissue and the precursor of collagen (COL IA1) were poorly detected in the gastric ulcer with AM application. Conclusion Using fresh AM allograft for repairing gastric mucosal defect in dogs showed great impact as a novel method to achieve optimum reconstruction of the gastric mucosal architecture and restoration of pre-epithelial, epithelial, and post-epithelial normal gastric mucosal barriers.
... Finally, amnion has been also used as an allograft in general surgery for reconstructions, as an autograft in neonatal reconstruction surgery, and as a scaffold in tissue engineering research. [17][18][19][20][21][22][23] amnIon vs chorIon • Amnion and chorion, both are part of the extraembryonic membranes, which function in an embryo's overall development. They also play important roles in the embryo's nourishment, breathing, and seepage • The amnion is a thin but tough sac of membrane that covers an embryo. ...
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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.
... It is well known that intact AM consists of an epithelial monolayer with a thick basement membrane and an adjacent stroma-the spongy layer side, both exhibiting different biological properties [10]. The amniotic epithelium produces different growth factors, which may promote proliferation and differentiation of limbal epithelial cells [11]. Thus, limbal epithelial cells are preferentially cultured on the epithelial side of the AM (or on the basement membrane side if denuded AM is used). ...
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Purpose To evaluate the effect of prolonged limbal explants cultured without any scaffolds or on amniotic membrane (AM) on the viability, proliferation and differentiation potential of putative phenotypically defined cultured limbal mesenchymal (LMSC) and epithelial stem cells (LESC). Methods Limbal explants were cultivated on cryopreserved intact AM or plastic plates using medium supplemented with only human serum. AM was positioned with either the epithelial or stromal side up. The outgrowing cells were immunophenotyped for the co-expression of mesenchymal stem cell markers (CD73/CD90/CD105 positive and CD45 negative), proliferation and putative progenitor markers (CXCR4, CD117), epithelial markers and antigen presenting cell markers (CD80, CD83, CD86) by flow cytometry. Immunohistochemistry on limbal cultures cultivated on AM was carried out with antibodies against pan-cytokeratin, p63, Ki67. Results Morphological and immunostaining analyses revealed two distinct stem cell population types, which could be identified over prolonged culturing time periods. Expression of LMSC markers and CXCR4 was significantly higher (p < 0.05) in cultures cultivated without AM. However, no statistically significant difference was observed in CD117 expression. The cells cultivated on AM retained an epithelial cell structure, which was further confirmed by histology examination. Histology revealed limbal epithelial growth and p63, Ki67 positive cells on both sides of AM. Conclusion Limbal cells cultivated on AM exhibited a lower expression profile of LMSC and CXCR4 markers as limbal cells cultivated on plastic culture plates. However, CD117 expression was similar. Histology confirmed limbal epithelial cell growth on both sides of AM, with no morphological differences, or positivity of cells for p63 and Ki67.
... Thereafter, it has been widely used for various ocular surface reconstructions. The unique property of amniotic membranes (AMs) in the reconstruction of ocular surfaces is that the AM contains a remarkable mixture of growth factors and cytokines facilitating proliferation and differentiation of epithelial cells, reducing the inflammatory response by inhibiting protease activity, and reducing inflammatory cell activity [4][5][6]. Therefore, AMT could promote ocular surface tissue healing of persistent epithelial defects (PEDs), corneal ulcers, and eye burns [7][8][9][10]. Clinical results showed that the success rate of treatment for corneal ulcers with single or multilayer AMs was over 80% [10,11], while for cornea perforation with multilayer AMT it was about 73% [12]. ...
Article
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In our retrospective study we evaluated the efficacy of an improved amniotic membrane (AM) roll-in filling technique (AMR) combined with multilayer amniotic membrane cover to treat corneal perforation and included 46 cornea perforations ≤ 3 mm in diameter treated with AMR and 20% C 3 F 8 mixed gas filling of the anterior chamber. Anterior chamber depth, aqueous leakage, bubble maintenance time, and cornea morphology were monitored after each operation. The mean diameter of corneal perforation was 1.60 ± 0.55 mm (range 0.5–3) and the success rate of the AMR method for corneal perforation reconstruction was 100% after a single operation. Anterior chamber depth was normally reconstructed without AMR break-off, aqueous leak, or other complications. The mean time of the C 3 F 8 gas bubble in the anterior chamber was 8.6 ± 2.0 days (range 4–12). At the last follow-up, all patients’ visual acuity was improved to varying degrees. The mean follow-up time was 11.0 ± 5.6 months (range 3–36). The AMR plugging combined with multilayer AM cover is a secure and easy intervention, which led to 100% success in our study. Various perforations ranging from trauma to infection can be treated with AMR, which is especially practical in those countries where donor cornea availability is limited.
... In cases of partial LSCD, amniotic membrane can be applied to the affected eye and provide a suitable substrate for corneal epithelial repopulation [82,83]. The amniotic membrane secretes several growth factors such as hepatocyte growth factor, basic fibroblast growth factor, and transforming growth factor β [84,85]. Amniotic membrane is suggested to exert its effects by suppressing inflammation and scarring [86]. ...
Article
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The cornea is critical for normal vision as it allows allowing light transmission to the retina. The corneal epithelium is renewed by limbal epithelial cells (LEC), which are located in the periphery of the cornea, the limbus. Damage or disease involving LEC may lead to various clinical presentations of limbal stem cell deficiency (LSCD). Both severe pain and blindness may result. Transplantation of cultured autologous oral mucosal epithelial cell sheet (CAOMECS) represents the first use of a cultured non-limbal autologous cell type to treat this disease. Among non-limbal cell types, CAOMECS and conjunctival epithelial cells are the only laboratory cultured cell sources that have been explored in humans. Thus far, the expression of p63 is the only predictor of clinical outcome following transplantation to correct LSCD. The optimal culture method and substrate for CAOMECS is not established. The present review focuses on cell culture methods, with particular emphasis on substrates. Most culture protocols for CAOMECS used amniotic membrane as a substrate and included the xenogeneic components fetal bovine serum and murine 3T3 fibroblasts. However, it has been demonstrated that tissue-engineered epithelial cell sheet grafts can be successfully fabricated using temperature-responsive culture surfaces and autologous serum. In the studies using different substrates for culture of CAOMECS, the quantitative expression of p63 was generally poorly reported; thus, more research is warranted with quantification of phenotypic data. Further research is required to develop a culture system for CAOMECS that mimics the natural environment of oral/limbal/corneal epithelial cells without the need for undefined foreign materials such as serum and feeder cells.
... 34 35 Such epithelial promoting actions are further augmented by the fact that the amniotic membrane can release several supportive growth factors. 36 In this study, the amniotic membrane was sutured as a graft only to cover the ulcerated area. As described in our earlier report 13 and recently by Kruse et al, 15 under this membrane we usually laid more than one layer of membrane to build up the corneal thickness in eyes with deep ulcers or descemetocele. ...
Article
AIMS To evaluate whether amniotic membrane transplantation can be an effective alternative treatment for neurotrophic corneal ulcers. METHODS Amniotic membrane transplantation was performed in 16 eyes of 15 patients with neurotrophic corneal ulcers and vision equal to or worse than 20/200. The neurotrophic state was developed following keratoplasty (four eyes), herpes zoster ophthalmicus (four eyes), diabetes mellitus (four eyes), radiation (two eyes), removal of acoustic neuroma with neuroparalysis (one eye), and herpes simplex keratitis (one eye). RESULTS During a mean follow up period of 18.8 (SD 13.0) months, one to three layers of amniotic membrane with or without additional membrane as a patch were used for 17 procedures in 16 eyes for persistent neurotrophic corneal ulcers. All but four (76.4%) instances of amniotic membrane transplantation achieved rapid epithelialisation in 16.6 (9.0) days. Of the four eyes showing delayed healing, three eyes healed by tarsorrhaphy, and the remaining one eye with corneal perforation required penetrating keratoplasty and tarsorrhaphy. Two eyes gained vision better than 20/200. The healed corneal surface was accompanied by reduced inflammation. CONCLUSION Amniotic membrane transplantation can be considered an effective alternative for treating severe neurotrophic corneal ulcers.
... İçeriğinde kornea epitel hücreleri üzerine trofik etkileri olan büyüme faktörleri ile enfeksiyona karşı koruyucu etki gösteren IgG ve lizozimi bir arada barındıran otolog serum, epitelyal iyileşme sürecini hızlandırarak topikal anesteziklere bağlı keratopati tedavisinde faydalıdır. Diğer yandan salgıladığı büyüme faktörlerinin etkisi ile korneada reepitelizasyonu artıran, [6] enflamatuvar hücrelerin apoptotik ölümünü uyarırken, epitelyal hücrelerin apoptotik ölümünü önleyen, [7] sahip olduğu kimyasal mediatörlerin etkisi ile yara iyileşmesine katkı sağlayan [8] amniyon membranı, bu özellikleri ile topikal anesteziklerin yol açtığı Toksik keratopatiler epitel defektinin yanı sıra halka şeklinde stromal infiltrasyonlarla karakterizedir, ancak topikal anestezik keratopatisi, halkasal stromal infiltrasyon bulgusu ile Acanthamoeba ve Herpes simplex keratitlerini taklit edebilir. [9] Bu nedenle halkasal stromal infiltrasyonla birlikte görülen keratitlerde topikal anesteziklerin yol açtığı toksik keratopatiler düşünülmelidir. ...
... Não se sabe com clareza se a promoção da epitelização é mediada pela matriz estromal, por fatores de crescimento ou por ambos (11) . ...
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OBJETIVOS: Avaliar o efeito do transplante de membrana amniótica no alívio da dor e melhora dos defeitos epiteliais recorrentes em portadores de ceratopatia bolhosa assintomática e pobre potencial visual. MÉTODOS: Foi realizado estudo prospectivo com 9 pacientes, no período compreendido entre abril/2000 e dezembro/2001 no Serviço de Oftalmologia do Hospital Universitário Evangélico de Curitiba - HUEC. Pré-operatoriamente, a história médica de cada paciente foi avaliada e exame oftalmológico completo foi realizado. Os pacientes foram avaliados com freqüência maior ou igual a uma vez por semana, incluindo o 1º pós-operatório (PO), 7º PO, 14º PO e 30º PO dia. Avaliação mensal foi realizada até o 6º mês pós-operatório. RESULTADOS: A amostra foi composta por 3 (33,3%) pacientes do sexo masculino e 6 (66,6%) pacientes do sexo feminino, com idade entre 29 e 74 anos. Todos os pacientes apresentavam dor ocular, 7 (77,7%) apresentavam lacrimejamento, 8 (88,8%) pacientes queixavam-se de fotofobia e 4 (44,4%) apresentavam olho vermelho. A acuidade visual no pré-operatório era conta dedos em 6 (66,6%) pacientes, movimento de mãos em 2 (22,2%) pacientes e amaurose em 1 (11,1%) paciente. Após o procedimento, observou-se reepitelização de todos os pacientes entre o 12º e 21º dia pós-operatório. Os pacientes apresentaram melhora da dor e fotofobia após a 1ª semana do transplante de membrana amniótica e permaneceram assintomáticos até o final do seguimento. CONCLUSÃO: A membrana amniótica tem potencial para restaurar a superfície corneana em pacientes com ceratopatia bolhosa sintomática, reduzindo a dor desses pacientes em pouco tempo. Contudo, o número de pacientes avaliados é pequeno e o seguimento curto, mas essa terapêutica é uma alternativa que tem nos encorajado, assim como a outros pesquisadores, devido ao excelente resultado obtido.
... Ela apresenta várias propriedades, como efeito antiadesivo da conjuntiva, proteção da ferida, adesão e migração das células epiteliais basais, redução de fibrose, prevenção da apoptose e restauração do fenótipo epitelial corneano (Kim e Tseng, 1995). Possui ação antibacteriana (Kjaergaard et al., 2001), antiinflamatória (Shimmura et al., 2001), inibidora de proteinases , além de conter diversos fatores de crescimento, como EGF, TGFβ, HGF, que estimulam a reepitelização (Sato et al., 1998). Outra propriedade atribuída a ela é de não induzir a rejeição após o transplante, pelo fato de não expressar a maioria dos antígenos de histocompatibilidade HLA, causando mínima ou nenhuma resposta inflamatória (Houlihan et al., 1995). ...
Article
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Changes related to limbal stem cells deficiency in corneal epithelium in rabbits, as well as the results of amniotic membrane transplant on the cicatrisation were evaluated. The ulcer was induced with n-heptanol associated to 360° conjunctival peritomy; the corneal surface was covered with canine amniotic membrane, sutured to perilimbal episclera, cryopreserved in embryo solution or own medium, both with 50% glycerol and stored at -80°C. The control group was not treated with membrane. Histological evaluations were performed at seven, 15, and 30 days. All of them developed limbal stem cells deficiency, named conjunctivalization, with neovascularization, inflammation and recurrent epithelial defects, observed in histopathology by the occurrence of neovascularization, edema, leukocytes and goblet cells. Thus amniotic membrane transplantation was not efficient in the treatment of limbal stem cells deficiency, however it helped in the process of cicatrisation.
... In addition, the AM produces basic fibroblast, hepatocyte and transforming growth factor (TGF). These growth factors together can stimulate epithelialisation, modulate proliferation, and induce differentiation of stromal fibroblasts [30]. ...
Article
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Mooren's ulcer is a severe ulcerative inflammation of the cornea. The exact pathogenesis remains unclear. Therefore many therapies of Mooren's ulcer are recommended in literature. To shed more light on the ongoing question of optimal treatment of severe progressive Mooren's ulcer, we here report on a retrospective case series of patients treated with systemic immunosuppressive therapy and additional amniotic membrane transplantation. Medical records from seven patients (eleven eyes), 4 male and 3 female, with severe progressive Mooren's ulcer were analysed retrospectively. The mean follow up was 88.4 +/- 80.8 months (range 12-232 month). A HLA-typing was performed in all patients. A systemic immunosuppressive therapy was administered in all patients. The amniotic membrane was transplanted after the base of the ulcer was resected. Multiple amniotic membrane transplantations were necessary in six patients. The visual outcome of all patients was poor. No patient achieved a visual acuity better than 20/630 Snellen chart. Five patients were positive for HLA-DQ2 and four patients were positive for HLA-DR17(3). The aggressive and highly inflammatory form of Mooren's ulcer is difficult to treat and the progression of the disease is hard to influence positively even under systemic immunosuppressive therapy. Therefore, the main intention of therapy is to achieve a stable epithelialized corneal surface without the risk of perforation. Amniotic membrane transplantation is not able to cure severe forms of Mooren's ulcer. However it supports the immunosuppressive therapy in acute situations as in critical corneal thinning.
... Não se sabe com clareza se a promoção da epitelização é mediada pela matriz estromal, por fatores de crescimento ou por ambos (11) . ...
Article
Full-text available
OBJETIVOS: Avaliar o efeito do transplante de membrana amniótica no alívio da dor e melhora dos defeitos epiteliais recorrentes em portadores de ceratopatia bolhosa assintomática e pobre potencial visual. MÉTODOS: Foi realizado estudo prospectivo com 9 pacientes, no período compreendido entre abril/2000 e dezembro/2001 no Serviço de Oftalmologia do Hospital Universitário Evangélico de Curitiba - HUEC. Pré-operatoriamente, a história médica de cada paciente foi avaliada e exame oftalmológico completo foi realizado. Os pacientes foram avaliados com freqüência maior ou igual a uma vez por semana, incluindo o 1º pós-operatório (PO), 7º PO, 14º PO e 30º PO dia. Avaliação mensal foi realizada até o 6º mês pós-operatório. RESULTADOS: A amostra foi composta por 3 (33,3%) pacientes do sexo masculino e 6 (66,6%) pacientes do sexo feminino, com idade entre 29 e 74 anos. Todos os pacientes apresentavam dor ocular, 7 (77,7%) apresentavam lacrimejamento, 8 (88,8%) pacientes queixavam-se de fotofobia e 4 (44,4%) apresentavam olho vermelho. A acuidade visual no pré-operatório era conta dedos em 6 (66,6%) pacientes, movimento de mãos em 2 (22,2%) pacientes e amaurose em 1 (11,1%) paciente. Após o procedimento, observou-se reepitelização de todos os pacientes entre o 12º e 21º dia pós-operatório. Os pacientes apresentaram melhora da dor e fotofobia após a 1ª semana do transplante de membrana amniótica e permaneceram assintomáticos até o final do seguimento. CONCLUSÃO: A membrana amniótica tem potencial para restaurar a superfície corneana em pacientes com ceratopatia bolhosa sintomática, reduzindo a dor desses pacientes em pouco tempo. Contudo, o número de pacientes avaliados é pequeno e o seguimento curto, mas essa terapêutica é uma alternativa que tem nos encorajado, assim como a outros pesquisadores, devido ao excelente resultado obtido.
... Amniyotik membran bazal membran epitel hücrelerinin migrasyonunu kolaylastirmakta (32,39), bazal epitelyal hücrelerin adezyonunu kuvvetlendirmekte (26) ve epitel farklilasmasini kolaylastirmakta (29)(30)(31)dir. Aynca amniyotik membran basic fibroblast growth faktör (bFGF), hepatosit growth faktör (HGF) ve transforming growth faktör-p (TGF-P) gibi epitelizasyonu uyarabilen büyüme faktörleri üretmektedir (25,40). Ancak bu faktörlerde kriyoprezervasyonla azalma ortaya çikmaktadir (32). ...
... (12) Although multilayer AMT has recently been used for reconstruction of deep ulcers in herpetic keratitis, neurotrophic keratitis, (10) and sterile corneal and scleral ulcers, to the best of our knowledge, there is no report on using AMT as an alternative treatment for bacterial keratitis in the acute stage. Given its properties as a promoter of reepithelialization, (31,32) the AM might be considered an alternative reconstructive material for promoting wound healing and preventing perforation in pseudomonal keratitis. However, several issues remain to be clarified in the event of treating infectious diseases with AMT, mainly because it is often feared that applying AMT to a cornea with acute infection will interfere with antibiotic treatment. ...
Article
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Ocular surface disorders (OSD) are challenging to treat. They can introduce serious morbidity and might even lead to visual loss. In such situations, keratoplasty remains the last option. Amniotic membrane transplantation (AMT) has been shown to be effective in the management of ocular surface pathologies. The aim of the study was to assess the efficacy of AMT for various indications of OSD. Experience of AMT in 65 patients with different OSD was evaluated. The aim of AMT was to achieve symptomatic relief, reduced inflammation, recurrence, and corneal haze; improve epithelization, stromal healing and visual acuity; and delay keratoplasty. Fresh amniotic membrane was used in all cases by a single surgeon. Follow-up and observations were done to evaluate success of achieving the goal. Indications for AMT included primary and recurrent pterygium, various types of corneal ulcers (non-healing ulcer, descemetocele, corneal thinning and perforation), spheroidal degenerations, chemical burn and bullous keratopathy. The aim of AMT was different in different etiological indications. Postoperative follow-up was between 6 and 18 months. Success and complication rate were observed. Symptomatic relief (reduced pain and redness) was seen in patients with various corneal ulcers, chemical burn and bullous keratopathy. Improved epithelialization and stromal healing was noted in corneal ulcer cases. In spheroidal degenerations, keratectomy with AMT improved vision. Recurrence of pterygium was low (4.61%); graft failure in the form of graft rejection was seen in only 3.07% cases of acute keratitis. Corneal vascularization (4.61%) was present but not severe enough to hamper vision. Success in gaining intended effect was the most significant result with AMT. AMT in various ocular surface pathologies shows success in achieving the goal of symptomatic relief, improved epithelialization, stromal healing and vision. Reduction in inflammation, corneal haze and recurrence of original disease is achieved with minimum complications.
... The AM stroma also contains a number of growth factors, various antiangiogenic and anti-infl ammatory proteins, and natural inhibitors to various proteases (Sato et al 1998). In view of all of the above-mentioned properties of the AM, there is little doubt that it provides an ideal stromal niche desirable for stem cell expansion. ...
Article
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Severe damage to cell repair mechanisms of the limbal region can lead to many disorders such as vascularized conjunctivalization, keratinization, corneal scarring, and corneal opacification, collectively described as limbal stem cell deficiency (LSCD). Limbal stem cell deficiency may occur as a result of depletion of stem cells or destruction of their stromal niche. In such cases, apart from conventional corneal transplantation, limbal stem cell transplantation would be needed to restore vision. Limbal stem cells may be replenished by autologous limbal transplants from the healthy fellow eye in unilateral cases, and allografts from living related donors or cadaveric donors in bilateral cases. The induction of iatrogenic LSCD and its sequelae in donor eyes have motivated researchers to cultivate sheets of limbal epithelium ex vivo, from small fragments of donor tissue for the purpose of ocular surface reconstruction.
... 11 Another mechanism by which AM transplantation might affect ocular surface reepithelialization is via the action of growth factors. Some researchers have started to investigate this possibility, [12][13] but as yet the identities and relative levels of growth factors in AM have not been ascertained. To help remedy this, we used RT-PCR to determine the expression in preserved AM of mRNA for several different growth factors. ...
Article
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To investigate the expression of growth factor mRNA and the level of growth factor protein in preserved human amniotic membrane (AM). RT-PCR was used to examine the expression of mRNA for eight growth factors (EGF, TGF-alpha, KGF, HGF, bFGF, TGF-beta1, -beta2, -beta3) and two growth factor receptors (KGFR and HGFR) in human AM preserved at -80 degrees C for one month. In addition, ELISAs were used to measure the protein concentrations of seven growth factors (EGF, TGF-alpha, KGF, HGF, bFGF, TGF-beta1, -beta2) in preserved human corneas and in AM both with and without amniotic epithelium. RT-PCR revealed that human AM expresses mRNA for EGF, TGF-alpha, KGF, HGF, bFGF, TGF-beta1, -beta2, -beta3, KGFR and HGFR, while ELISAs showed that it contains EGF, TGF-alpha, KGF, HGF, bFGF, TGF-beta1, -beta2. AM without amniotic epithelium also contains all seven growth factors examined, however, in this tissue the protein levels of EGF, KGF, HGF and bFGF were found to be significantly lower than in native AM. Preserved human AM expresses mRNAs for a number of growth factors and contains several growth factor proteins that might benefit epithelialization after AM transplantation. High levels of EGF, KGF, HGF and bFGF in AM with amniotic epithelium as compared to AM without amniotic epithelium suggest an epithelial origin for these growth factors. We feel that EGF, KGF and HGF in particular might play important roles in ocular surface wound healing after AM transplantation.
... 34 35 Such epithelial promoting actions are further augmented by the fact that the amniotic membrane can release several supportive growth factors. 36 In this study, the amniotic membrane was sutured as a graft only to cover the ulcerated area. As described in our earlier report 13 and recently by Kruse et al, 15 under this membrane we usually laid more than one layer of membrane to build up the corneal thickness in eyes with deep ulcers or descemetocele. ...
Article
Full-text available
To evaluate whether amniotic membrane transplantation can be an effective alternative treatment for neurotrophic corneal ulcers. Amniotic membrane transplantation was performed in 16 eyes of 15 patients with neurotrophic corneal ulcers and vision equal to or worse than 20/200. The neurotrophic state was developed following keratoplasty (four eyes), herpes zoster ophthalmicus (four eyes), diabetes mellitus (four eyes), radiation (two eyes), removal of acoustic neuroma with neuroparalysis (one eye), and herpes simplex keratitis (one eye). During a mean follow up period of 18.8 (SD 13.0) months, one to three layers of amniotic membrane with or without additional membrane as a patch were used for 17 procedures in 16 eyes for persistent neurotrophic corneal ulcers. All but four (76.4%) instances of amniotic membrane transplantation achieved rapid epithelialisation in 16.6 (9.0) days. Of the four eyes showing delayed healing, three eyes healed by tarsorrhaphy, and the remaining one eye with corneal perforation required penetrating keratoplasty and tarsorrhaphy. Two eyes gained vision better than 20/200. The healed corneal surface was accompanied by reduced inflammation. Amniotic membrane transplantation can be considered an effective alternative for treating severe neurotrophic corneal ulcers.
Article
Purpose To study the presence of certain proteins - EGF (epidermal growth factor), KGF (keratinocyte growth factor), IL-10 (interleukin 10), HGF (hepatocyte growth factor), Alpha2-macroglobulin and IL-1RA (interleukin 1 receptor antagonist) in cryopreserved amniotic membranes at 1 and 18 months and, as a secondary objective, to detect mRNA corresponding to KGF, IL-1Ra, Alpha2-macroglobulin, Fas Ligand, TGF beta (transforming growth factor beta) and Lumican by RT-PCR in membranes preserved at 1 and 18 months. Material and methods Four samples of amniotic membrane were divided into 2 groups: the first group (N = 2) cryopreserved for 1 month and the second group (N = 2) cryopreserved for 18 months, in order to be studied by RT-PCR and ELISA. Results RT-PCR detected KGF, IL-1Ra, Alpha2-macroglobulin, Fas Ligand, and Lumican. Of these, FAS Ligand mRNA was found in samples preserved for 1and 18 months. KGF, Lumican, and alpha2-microglobulin mRNA were found only at 1 month, and IL-1Ra mRNA was absent in both sample groups. RT-PCR for TGF-beta was inconclusive. ELISA was performed for detection and quantification of 6 proteins (EGF, KGF, IL-10, HGF, Alpha2-macroglobulin and IL-1Ra) in both amniotic membrane groups. All 6 proteins were found in all samples, with a lower concentration at 18 months compared to 1 month of preservation. Conclusion This study shows that membranes cryopreserved in 50% glycerol for 18 months do retain the proteins necessary for regeneration of the corneal surface, giving these membranes their biochemical properties.
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Purpose: To evaluate the long-term results of the efficacy of amniotic membrane transplantation in acid burn, alkali burn, thermal burn and Stevens-Johnson syndrome (SJS). Design: Prospective interventional case series. Participants: 15 patients with acid burn, 5 patients with alkali burn, 1 patient with thermal burn and 9 patients with SJS were included. Methods: Amniotic membrane was processed under sterile conditions from a fresh placenta obtained from cesarean section in a seronegative pregnant woman and stored at-70°C. Release of symblepharon, epibulbar fibrous tissue excision and corneal fibro vascular membrane clearing was done. Obliterated fornices found in all 9 patients with SJS and 7 patients with ocular chemical burn were reconstructed were deepened by the use of fornix-formation sutures. Symblepharon ring was placed post-operatively in all eyes for 2weeks to 3 months. Mean follow-up period was 24 months. Main outcome measures: Integrity of ocular surface epithelium, restoration of adequate bulbar surface free of symblepharon and visual acuity during the 24 months of follow-up. Results: Complete corneal epithelialization occurred between 1 to 5 weeks in all eyes except for 1 patient with acid burn. All eyes were free of symblepharon at the final follow-up. 9 patients with acid burn and 1 patient with thermal burn had some residual stromal clouding at final follow-up. Cicatricial entropion of lower eyelid of 1 patient with SJS resolved with AMT. Limbal ischemia resolved in all patients except for the solitary patient with thermal burn. Visual acuity improved in 8 patients with acid burn, all 5 patients of alkali burn, and 2 patients with SJS. Conclusion: Amniotic membrane transplantation promotes re-epithelialization, restores adequate ocular surface and prevents recurrence of symblepharon in severe ocular surface disorders.
Article
To investigate if a suspension made with amniotic membrane could have a beneficial effect on ocular surface diseases. In the Imola branch of the Eye Bank of Emilia Romagna, the authors prepared a suspension containing homogenized amniotic membrane previously conserved at -80 degrees Celsius. Subsequently, the authors gave this preparation to 21 patients: 8 had undergone lamellar keratoplasty, 4 had undergone penetrating keratoplasty, 2 had undergone photorefractive keratectomy with a delay of epithelialization, 3 had neurotrophic corneal ulcers, 2 had corneal burning, 1 had torpid corneal ulcer, and 1 had Sjogren syndrome. Each patient had been treated with conventional therapy for at least, 4 months without any clinical improvement. In this sample of eyes the authors evaluated the transparency and integrity of epithelium before and after the therapy by means of a fluorescein staining test, examining the area of epithelial defect as well as the phlogistic situation and the symptoms referred by patients. Nine eyes from this group of patients were studied by impression cytology before and after 3 months of use of suspension. The follow-up was 5 months of once-weekly visits. In all patients, after 15 to 30 days the corneas became negative to fluorescein staining test and the epithelium seemed more complete and regular, there was an evident decrease of phlogistic situation in the conjunctiva, and an improvement of symptoms was referred by patients. The situation was stable during the whole follow-up. No side effects were noted. The impression cytology repeated 3 months after the treatment showed a significant corneal recovery of the cytologic situation with an important decrease of CK19+ cells on the corneal surface. This new therapy, which is less traumatic than an implant of amniotic membrane, is safe, and can be repeated for a long period, could help patients with corneal superficial defects.
Article
Aim: Eye surface burn is easy to cause blindness. Ammiotic membrane transplantation has become a hot spot of research for its special effects in recent years. This study observed the therapeutic outcome of fresh amniotic membrane transplantation for acute chemical or thermal burns at eye surface. Methods: 1 Eight eyes with acid burn in eight cases, ten eyes with alkali burn in ten cases, and seven eyes with thermal burn in six cases were selected from Yan'an University Affiliated Hospital between January 2002 and June 2007 including 23 males and 1 female aged 16-50 years. There were 18 eyes with preoperative vision < 0.05, 6 eyes with 0.06-0.1, and 1 eye with 0.25. 2 Amniotic membrane from the caesarean delivered fresh placenta (informed consent from the parturient) was separated by blunt dissection from the hidden lacune between amniotic membrane and chorionic vesicle, stored at 4 °C for 24 hours. All 25 eyes with acute eye surface burns of 24 cases were treated by monolayer or multilayer fresh amniotic membrane transplantation in combination with regular medicine treatment. 3 Amniotic membrane adherence, corneal transparency, epithelium recovery and fiber proliferation were observed after surgery. All the patients were followed up for 3-6 months with an average of 4.5 months. Results: In 24 eyes, epithelium was recovered and ocular surface stabilized rapidly with no rejection; cornea regained transparent to certain extent. The vision of 24 eyes was significantly improved compared with preoperative one (P < 0.01). Epithelium of 1 eye failed to recover because of the necrosis of 3/4 corneal limbus, and treated by second limbal stem cell transplantation. Conclusion: Fresh amniotic membrane can effectively reduce inflammation, block corneal melting, accelerate ocular surface reconstruction, reduce the growth of blood vessel, and relieve cicatricle. Moreover, the amniotic membrane resource is sufficient, and the cost is low. Fresh amniotic membrane transplantation is an effective way to treat eye burns at acute stage.
Article
Objective: To study the expressions of hepatocyte growth factor (HGF), basic fibroblast growth factor (bFGF), collagen type IV (Col IV) and laminin (LN) in preserved amniotic membranes (AMs), and explore the biological vitalities of preserved AMs. Methods: The amniotic membranes from the healthy puerpera underwent Cesarean section were preserved under the condition of DMEM/glycerol at -80°C or glycerol at 4°C respectively. Immunohistochemistry with image analysis system was used to investigate the changes of expressions of HGF,bFGF,ColIV and LN and compared with fresh AMs at 1 and 3 months after preservation. Results: HGF and bFGF expressed mostly in AM epithelium. HGF was detected in the epithelial cells of AMs at 1 and 3 months in both groups, but the expression of bFGF at 3 months in both groups was significantly decreased in comparison with fresh AMs (P < 0.01). The major expressions of Col IV and LN were found in AMs basement membrane in both groups with no significant differences (P > 0.05). Conclusion: Expressions of HGF and bFGF are decreased in AMs preserved under the condition of DMEM/glycerol at -80°C and in glycerol at 4°C, and this result indicates that the potencies of HGF and bFGF are gradually reduced with prolongation of preservation time, but the components of basement membrane from preserved AMs remain similar to fresh AMs.
Article
• Aim: To observe the therapeutic effect of fresh multilayer amniotic membrane transplantation combined with conjunctival reconstruction for treatment of conjunctival sac stenosis. • Methods: Fifty-two patients (52 eyes) suffered from conjuctival sac stenosis were treated with fresh multilayer amniotic membrane transplantation. The superior and lower eyelid was closed with mattress suture. The eyelids were opened and stained with fluorescein test paper every week in order to observe the growth of conjunctival epithelium. Stitches were removed three months after surgery and the suitable prosthesis was made. • Results: Conjunctival epithelium migrated to the surface of the amniotic membrane and covered it completely in 51 cases four weeks after surgery. Amniotic membrane was dissolved and conjunctival epithelium could not cover the defect area in one case. Three months after surgery, 15 eyes of degree ¢ æ cojunctival sac constriction (group A) were all cured. In degree ¢ cojunctival sac constriction (group B), 15 eyes were cured and two eyes were improved. In degree ¢ cojunctival sac constriction (group C), 16 eyes were cured, 3 eyes were improved and 1 eye failed. There was no statistical difference of success rate between three groups. • Conclusion: Fresh multilayer amniotic membrane transplantation combined with conjunctival reconstruction is effective for treatment of conjunctival sac stenosis of degree ¢æ, ¢ and ¢.
Article
Aim: To prepare and preserve human amniotic extracellular matrix (AECM) and investigate the structural characteristics of AECM prepared immediately and preserved for middle to long term. Methods: The experiment had been accomplished at Center of Medical Science Research of Gannan Medical College from January to December in 2004. 1 Pieces of AECM were prepared and preserved by international recognized methods as amniotic membrane. 2 Immediate-term prepared AECM prepared freshly were gained, middle-term preserved AECM (preserved for a week at 4 °C), and long-term preserved AECM (preserved for three months at -80 °C). The configuration and structure characteristics of AECM were observed with sight, light microscope (LM), transmission electron microscope (TEM) and scanning electron microscope (SEM). Results: 1 AECM observed under sight: AECM prepared immediately and preserved for middle to long term respectively was a kind of lucent, colorless and definitely tough biomembrane whose thickness was about 0.02-0.4 mm. 2 AECM observed under LM: There were two layer structures at AECM prepared immediatelv and preserved for middle to long term. One was the basal lamina that was uneven in thickness and had no cytoarchitecture; the other was the densa lamina that was composed of the connective tissue. AECM prepared and preserved for middle term were slightly thicker than that for long term. A few fibroblasts were observed with AECM prepared immediately, whereas few fibroblasts were observed with AECM prepared and preserved for middle to long term. 3 AECM observed under TEM and SEM: The thickness of the basal lamina of AECM prepared immediately and preserved for middle term was 0.1-0.2 μm; the thickness of the densa lamina was about 30-400 μm, and the majority of the densa lamina were collagen fibers, reticular fibers and ground substance and the fibroblasts were observed once in a while; The thickness of the basal lamina of AECM prepared immediately and preserved for long term was about 0.2-0.3 μm; the thickness of the densa lamina was about 20-400 μm, and the majority of the densa lamina were collagen fibers and reticular fibers, but the cytoarchitecture was not observed; The structures of the collagenous fibril were completely consistent among three different terms. Conclusion: The amnion is eliminated or killed its epithelia by the tissue engineering technique, and then forms AECM containing the basal lamina and the densa lamina. Because the main compositions of AECM are collagen fibers and reticular fibers and the immunogenicity of AECM is lower than that of the amnion, and AECM is a kind of special extracellular matrix. As a kind of membrane or biologic skeleton attached with cells, it has expansive research and application in the future. Therefore, AECM can be applied on the basic investigation as a biologic carrier of cell culture in vitro.
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With the report on successful application of amniotic membrane transplantation in clinical ophthalmology, especially in the treatment of ocular surface diseases, the basic research on the application of amniotic membrane in ophthalmology field also gained more attention. In this paper, the histological, immunological, and biological characteristics of amniotic membrane in the field of ophthalmology clinical application were reviewed.
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BACKGROUND: In recent years, fibrin glue as a drug delivery carrier, has been attracting a growing attention. Ganciclovir is an effective broad-spectrum antiviral drug of viral keratitis. Therefore, we choose this drug in the initial exploration and research of drug delivery-fibrin glue-amniotic membrane. OBJECTIVE: To study the release characteristics of ganciclovir-fibrin glue-amniotic membrane and to explore a new method for clinical treatment of viral keratitis. METHODS: In vitro study: fibrin glue compounded with ganciclovir and amniotic membrane to prepare the ganciclovir-fibrin glue-amniotic membrane complex and the in vitro release characteristics of ganciclovir was studied. In vivo study: ganciclovir-fibrin glue-amniotic membrane complex was transplanted on right eyes of New Zealand rabbits as experimental group, and 1 g/L ganciclovir dropped into left eye, 100 μL was given in 5 eyes every 2 hours as the control. The ganciclovir concentration in the aqueous humors was assayed by high performance liquid chromatography. RESULTS AND CONCLUSION: In vitro release study revealed that the accumulative release rate of ganciclovir was (45.67±5.32)% 24 hours after incubation and rose to (63.42±4.68)% 48 hours later. The release process went to a balance condition 96 hours later. Animal indicated that the ganciclovir level in aqueous gradually reduced along with time. The drug level was significantly higher for experimental group than control at 1 day (P < 0.05); during 2-3 days, the drug level in aqueous of experimental group was higher than control group without significant differences; the ganciclovir level in aqueous of experimental group was lower than that of control group at 4-5 days (P < 0.05). The ganciclovir-fibrin glue-amniotic membrane complex has a good sustained release property both in vitro and in vivo, it may be a new treatment of viral keratitis.
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: Pterygium is a common worldwide external eye disease especially affecting population in tropical and subtropical areas. It is a wing shaped fold of conjunctiva encroaching upon the cornea from either side within the interpalpebral fissure. The present study was conducted in the Department of Ophthalmology, G.R. Medical College and JAH Gwalior (M.P.) from January2009 to June 2010. The study was conducted in 50 eyes of 50 patients of pterygium. They were randomly divided into two groups, Group A and Group B. In each Group 25 cases were included. Group A patients were surgically treated by Conjunctival limbal autograft and Group B patients by Amniotic membrane Graft. Maximum number of patients belongs to < 40 years of age (56.6%). Male were 34% and females were 16% in CLAG Group. In AMT Group 38% were male and 18% were female. Recurrences were 4(16%) cases in CLAG Group and 6(24%) cases in AMT Group. Study concluded AMT preserved the superotemporal conjunctiva and easy procedure, it has high recurrence rate. Conjunctival limbal autografts are technically demanding and time consuming, but they are more effective in preventing recurrences when compared with Amniotic membrane graft
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Avaliaram-se as alterações relacionadas à deficiência das células límbicas precursoras do epitélio corneano de coelhos e o efeito da membrana amniótica sobre sua cicatrização. A lesão, induzida com n-heptanol associado à peritomia conjuntival em 360°, foi recoberta com membrana amniótica canina, suturada à episclera perilímbica, criopreservada em meio para congelação de embrião ou em meio próprio, ambos com glicerol a 50% e mantida a –80°C. O grupo-controle não foi tratado com a membrana. As avaliações histológicas foram realizadas ao sétimo, 15º e 30º dias. Todos desenvolveram deficiência de células germinativas do limbo, denominada conjuntivalização, com presença de neovascularização, inflamação e defeitos epiteliais recorrentes, caracterizada na histopatologia pela presença de neovasos, edema, leucócitos e células caliciformes. O transplante de membrana amniótica não foi eficiente para o tratamento desta deficiência, entretanto auxiliou o processo de cicatrização da córnea.
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ABSTRACT Postoperative adhesion formation following complex strabismus surgery limits surgical outcomes. The benefits of amniotic membrane transplant (AMT) are widely recognized in ophthalmology. There are only published isolated case reports regarding its use in strabismus surgery. The limitation of these reports is that they describe use of AMT in cases of restrictive strabismus resulting from periocular surgery and indirect involvement of the extraocular muscles. In our series, the amniotic membrane was used to manage complex strabismus surgery. In this retrospective case series we describe surgical management with AMT in 8 strabismus cases between 2007 and 2010 in a tertiary referral center. Of these, 6 cases resulted from complex and repeat strabismus procedures to the extraocular muscles and 2 cases were a result of periocular surgery. Descriptive methodology was used. Outcomes examined were postoperative objective improvement in angle of deviation, subjective improvement in patient symptoms, and need for further interventions. Mean follow-up period was 15 months. All patients had multiple strabismus surgery in the past with a mean number of 3.2 ± 1.5 procedures (range 1-5). The indication for surgery using amniotic membrane graft was in 7 cases a large hypotropia with inferior conjunctival fibrosis and in one case a large consecutive horizontal deviation. The mean angle of vertical deviation was reduced from 32.1 ± 13 prism diopters (PD) preoperatively to 19.75 ± 11.4 PD postoperatively, with better outcomes in cases where AMT was used early in the surgical plan. Six out of the eight cases had objective improvement also consistent with improvement in the binocular field of vision. This is the largest reported case series on amniotic membrane grafts for strabismus surgery complicated by fibrosis and especially cases of consecutive hypotropia. Our outcomes indicate that AMT is beneficial, but we suggest it be used in the early stages of the surgical management of these cases.
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The purpose of this study is to report our clinical experience and the effect of human amniotic membrane transplantation on severe ocular surface diseases. From 1998 to 2000 at Sestre milosrdnice University Hospital amniotic membrane transplantation was performed consecutively in 27 eyes: 16 eyes had persistent corneal ulceration and 11 bullous keratopathy. In the group with persistent corneal ulceration the average time of epithelisation was 23.1 days and epithelial defect recurred after the AMT in 75%, while in the eyes suffering from bullous keratopathy epithelisation took place in 19.6 days in 72.7%. AMT can be considered an effective alternative for treating severe ocular surface disease.
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In 1910 Davis was the first to report the use of fetal membranes as surgical material in skin transplantation.1Since then the use of amniotic membrane in surgery has been expanded.1-9 It is now utilised as a biological dressing for burned skin, skin wounds, and chronic ulcers of the leg,9-16 as an adjunctive tissue in surgical reconstruction of artificial vagina,9 17-19 and for repairing omphaloceles.9 20 It has also been used to prevent tissue adhesion in surgical procedures of the abdomen, head, and pelvis.9 21 22 In the 1940s several authors reported the beneficial role of amniotic membrane in treating a variety of ocular surface disorders.5-7 23 However, its use was abandoned for decades until recently, when it was reintroduced to ophthalmologists. Several studies have addressed this subject and the scope of the application of amniotic membrane transplantation (AMT) in the management of ocular surface disorders is ever increasing. Certain characteristics make the amniotic membrane ideally suited to its application in ocular surface reconstruction. It can be easily obtained and its availability is nearly unlimited. The tissue can be preserved at −80°C for several months, allowing sufficient time to plan surgery or consider a trial of other options. Amniotic membrane does not express HLA-A, B, or DR antigens and hence immunological rejection after its transplantation does not occur.24-26It is also believed to have antimicrobial properties, reducing the risks of postoperative infection.27 Antifibroblastic activity28-30 and cell migration/growth promoting activity31-33 have also been demonstrated with regard to the amniotic membrane. The purpose of this paper is to review the characteristics of amniotic membrane that make it potentially useful to treat ocular surface abnormalities and to discuss the current indications, the surgical technique, and the outcome of AMT. Mammalian embryos lie …
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To determine whether amniotic membrane transplantation can be used to treat symptomatic bullous keratopathy displaying poor visual potential. Amniotic membrane transplantation was performed at 5 centers on 50 consecutive eyes (50 patients) with symptomatic bullous keratopathy and poor visual potential. The underlying causes of bullous keratopathy included aphakia (9 eyes), pseudophakia (19 eyes), failed grafts (9 eyes), and others (13 eyes). During the follow-up period of 33.8 weeks (3-96 weeks) after amniotic membrane transplantation, 43 (90%) of 48 eyes with intolerable pain preoperatively became pain free postoperatively. Among the 5 eyes with residual pain, 3 received repeated amniotic membrane transplantation, 1 required a conjunctival flap for pain relief, and 1 had reduced pain. Epithelial defects in 45 (90%) of 50 eyes created and covered by amniotic membrane healed rapidly within 3 weeks. Only 4 eyes (8%) showed recurrent surface breakdown. Epithelial edema or bullae recurred in a smaller area in 5 eyes (10%) and pseudopterygium developed in 1 eye. Amniotic membrane transplantation can be considered as an alternative to conjunctival flaps in alleviating pain, promoting epithelial healing, and preserving cosmetic appearance in patients with symptomatic bullous keratopathy and poor visual potential.
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To report the failure of amniotic membrane transplantation (AMT) for ocular surface reconstruction in patients with severe acute chemical and thermal burns. Four eyes of three patients who suffered severe chemical (n=3) and thermal (n=1) burns were studied. The aim of AMT was to prevent symblepharon formation, promote conjunctival regeneration, inhibit corneal melting by promoting epithelialisation, and to protect the ocular surface while associated lid burns were treated. AMT was used to cover the entire ocular surface of all the severely burnt and ischaemic eyes, 2-3 weeks after the injury. Where indicated, AMT was repeated by itself or in combination with other procedures in all patients. Three of the four eyes developed symblepharon and progressive corneal melt requiring urgent tectonic keratoplasty. All four eyes had persistent epithelial defects. Less than 25% of conjunctival regeneration occurred in three eyes. Two eyes autoeviscerated, one patient underwent lid sparing exenteration for a painful blind eye and one eye became phthysical. AMT did not help to restore the ocular surface or preserve the integrity of the eye in all our patients with severe acute burns, when used by itself or in combination with other surgical procedures. This reflects the extreme severity of the ocular burns in these patients and, in turn, draws attention to the fact that the current classification system does not adequately reflect such severity. In the current system such burns would be grouped under grade IV injuries to the eye (more than 50% limbal ischaemia). The prognosis of patients with 100% limbal ischaemia is much worse than patients with just over 50% limbal ischaemia. This inadequacy of the classification system probably also explains the difference between outcomes of management of grade IV burns (with AMT) in this series, compared with others.
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