Human Amniotic Membrane Transplantation Research Articles

A Novel Technique Using Lyophilized Amniotic Membrane Patch (LAMPatch) as Primary Procedure in Patients with Myopic Traction Maculopathy with Macular Detachment.

Maculopathy secondary to pathologic myopia (PM) is increasingly causing visual impairment and blindness worldwide. PM is associated with tractional maculopathy that ranges from macular foveoschisis to macular hole. These disorders are treated with different options that offer variable results, reflecting the need for new techniques that address myopic maculopathy with consistent outcomes. Since human amniotic membrane (HAM) has been reported to be safe for intraocular use and to promote retinal healing, it was incorporated as an adjuvant in pars plana vitrectomy in patients with different tractional disorders related to myopia. This work presents a prospective, consecutive case series of seven patients with high myopia who underwent a 25-gauge vitrectomy with ILM peeling and HAM transplantation. Our six-month results show that this novel technique delivers functional success related to tissue permanence without recurrence of traction that translates into visual acuity gain and maintenance that are superior to other techniques.

Clinical Outcomes and Indications of In-Office Sutureless Dried Gamma Ray-Sterilized Human Amniotic Membrane Transplantation With Bandage Contact Lenses in Various Ocular Surface Disorders.

The purpose of this study was to investigate the efficacy and indications of using dried gamma ray-sterilized amniotic membrane (AM) transplantation with bandage contact lenses for the in-office sutureless treatment of various ocular surface diseases. This study retrospectively included 56 eyes of 52 patients with various ocular surface diseases treated with sutureless dehydrated AM-assisted therapeutic contact lenses. The patients were followed up and assessed 1, 2, and 4 weeks after the treatment, and the therapeutic contact lenses were removed after 1 or 2 weeks. The size of the corneal lesion and the degree of pain experienced by each patient before and after the procedure were measured. Corneal re-epithelization rate and clinical aspects related to re-epithelialization were evaluated. Complete corneal re-epithelialization of the epithelial defect was observed in 40 eyes. The complete re-epithelialization rates of persistent epithelial defect caused by infectious ulcers, neurotrophic ulcers, ulcers due to burn, toxic keratopathy, previous penetrating keratoplasty or other corneal surgeries, and severe dry eye disease were 69.2%, 80.0%, 77.8%, 100%, 75.0%, and 100%, respectively. Five patients with uncontrolled infectious ulcers, neurotrophic ulcer, bullous keratopathy, and ulcers associated with rheumatic disease did not show significant improvement. Patient pain scores significantly decreased after the procedure. Dehydrated AM transplantation with a bandage contact lens is minimally invasive and easily applicable through in-office procedures. This approach is expected to be more actively applied in various ocular surface disorders, not only in severe corneal diseases but also in relatively mild corneal surface diseases.

Amniotic Membrane Transplantation for Reconstruction of Ocular Surface Lesion Excisions in Pediatric Population.

To define the use of human amniotic membrane transplantation (hAMT) for reconstruction of the ocular surface after ocular surface lesion excisions in pediatric population during the last decade in a tertiary eye center. A total of 31 patients who underwent hAMT procedure because of the excision of ocular surface lesions between January 2009 and December 2021 were included in this study. The medical data were retrospectively evaluated. The female-to-male ratio was 14/17. The mean age of the patients was 10.1±4.1 (range, 1-18) years. Although a single hAMT was applied to most of the cases (94.4%; 34 eyes), more than one hAMT was applied to 5.6% of cases (2 eyes). The amniotic membrane degradation duration was found to be 21.5±10.8 (range, 13-50) days. Amniotic membrane is used as a biomaterial in various ocular surface diseases with its anti-inflammatory, antimicrobial, and wound healing properties. Although widely used, there are only a few studies reporting its clinical efficacy in the pediatric age group. It seems to be safe and effective in pediatric age group for ocular surface reconstruction after ocular surface lesion excisions.

Combined umbilical cord patching with amniotic membrane graft for corneal surface reconstruction.

Umbilical cord patch (UCP) grafts have been successfully used for glaucoma shunt tube coverage and conjunctival surface reconstruction. In recent years, the technique has emerged as a novel alternative for the reconstruction of corneal perforation and descemetocele. This study aimed to evaluate the effectiveness of combined UCP grafting and human amniotic membrane (HAM) transplantation for the management of corneal perforation or descemetocele. This prospective, non-comparative, interventional case series included nine eyes of nine patients with corneal descemetoceles and 28 eyes of 28 patients with corneal perforations, all in a clinically quiescent state. UCP grafting and HAM transplantation were combined to treat all patients. We re-examined the patients daily throughout the first week, weekly for 1 month, and then monthly for the first 6 months using slit-lamp examination and anterior segment optical coherence tomography. We included 37 eyes with descemetocele or corneal perforation in a clinically quiescent state. The mean (standard deviation) ages of patients with corneal descemetocele and corneal perforation were 56.3 (18.8) years and 54.3 (18.1) years, respectively. The male-to-female ratios in patients with corneal descemetocele and corneal perforation were 56% to 44% and 61% to 39%, respectively. Postoperative corneal thickness increased significantly in eyes with descemetocele compared to preoperative values (P < 0.001). Postoperative best-corrected distance visual acuity improved significantly compared to preoperative values in eyes with descemetocele or corneal perforation (both P < 0.001), with relief of accompanying ocular symptoms. We did not observe any recurrence or complications such as rejection, infection, suture-related problems, or severe inflammation and all had a formed anterior chamber up to the final follow-up visit. Combined UCP grafting and HAM transplantation could be a promising alternative treatment for corneal perforation or descemetocele in clinically quiescent eyes, providing satisfactory reconstruction and functional outcomes. Further studies with robust designs, larger sample sizes, and longer follow-up are needed to verify the efficacy and safety of this modified surgical technique in enhancing vision and restoring anterior segment anatomical integrity in compromised corneas.

Impact of adjuvant amniotic membrane transplantation in infectious ulcerative keratitis.

To evaluate the effectiveness of cryopreserved human amniotic membrane transplantation (hAMT) in patients with infectious ulcerative keratitis. A retrospective cohort study based on medical records of patients who underwent hAMT procedure over a 2-year period (2020-2021) was conducted at Ege University Hospital, Turkey. Cryopreserved hAM was used. Best corrected visual acuity (BCVA) was measured with the Snellen chart. Detailed ophthalmological examination was performed at all visits. Treatment success was defined as complete healing including disappearance of corneal infiltrates, epithelial defect closure, reduction in anterior segment reaction. A total of 13 eyes of 12 patients were diagnosed with ulcerative keratitis between 2020 and 2021. hAMT was performed in severe keratitis patients in which corneal infiltrates extending to middle to deep stromal and patients with neurotrophic component, in other words, having trouble for wound healing. The mean age was 60.9 ± 18.7years, and 66.6% of the patients were male. Average ulcer horizontal diameter was 9.7 ± 2.8mm. A single-layer human amniotic membrane (hAM) was transplanted 92.3% of eyes. Overlay technique was used in all patients for hAMT. The mean residence time of the amniotic membrane on the ocular surface was 14.1 ± 10.2days. The mean time from the first presentation to the hAM transplantation was 9.7 ± 6.8days. The average hospitalization time of all patients was 15 ± 12.1days, pre-hAMT was 10.2 ± 7.3days and post-hAMT was 4.8 ± 9.1days. The mean follow-up time was 3months. Recovery response was positive in 76.9%. Average healing time was 32.1 ± 14.04days. hAMT was effective in the treatment of infectious ulcerative keratitis by accelerating and supporting wound healing. Performing hAM transplantation at the early stages of the disease and prolonged residence of membrane on the ocular surface increase the success of the treatment and moreover shortens hospitalization time.

Comparison of amniotic membrane transplantation with and without cultured limbal epithelium for persistent corneal ulcers

This study compared the clinical outcomes of amniotic membrane transplantation with and without cultured limbal epithelium for persistent corneal ulcers. The study included 30 patients that were assigned to either human amniotic membrane transplantation (AMT) only or a two-step cultured limbal epithelial transplant (CLET) with amniotic membrane carrier. The patients underwent a comprehensive ocular examination, Cochet-Bonnet esthesiometry, impression cytology and anterior segment optical coherence tomography (AS-OCT). Slit-lamp images before and after treatment were analyzed using ImageJ to compare the fibrovascular tissue area. The state of epithelialization was assessed by fluorescein staining on day 30. Mean age of patients was 64 ± 20.39 in the AMT group and 55.17 ± 14.51 in the CLET group (p = 0.16). Visual acuity improved significantly in both groups after treatment, but the improvement was significantly greater in the CLET group (p = 0.022). Impression cytology demonstrated PAS + cells in the corneal epithelium in 9 patients from the CLET group and 10 patients in the AMT group (p = 0.704). Cochet-Bonnet esthesiometry increased significantly after treatment with a similar rate between groups (p = 0.435). Improvement with reduction of the fibrovascular tissue area was achieved in both groups (p < 0.01 and p = 0.001 in the CLET and AMT group, respectively). Independent samples T-test demonstrated a greater reduction in the CLET group (p = 0.028). Kaplan-Meier analysis of epithelialization demonstrated higher success rate in the CLET group (p = 0.006). Persistent corneal ulcers could be associated with partial limbal stem cell deficiency (LSCD). In refractory cases, CLET should be the preferred treatment option with more sustainable results regarding corneal epithelialization and stromal scarring.

Amniotic membrane for retinal detachment due to paravascular retinal breaks over patchy chorioretinal atrophy in pathologic myopia.

To describe a new surgical technique, using a human amniotic membrane patch, in two cases of retinal detachment with paravascular retinal breaks over patchy chorioretinal atrophy in pathologic myopia, already underwent pars plana vitrectomy with the internal limiting membrane peeling for myopic foveoschisis. Surgical technique description with surgical video. A 23-gauge pars plana vitrectomy was performed. A human amniotic membrane patch was implanted under the neuroretina to seal the posterior retinal break. Standard silicone oil tamponade was performed at the end of the surgery. The patients were positioned face down after the operation for the first week. Optical coherence tomography scans were used in the follow-ups. The 2 weeks postoperative optical coherence tomography showed a new tissue growth over the human amniotic membrane patch. The 3 months optical coherence tomography showed the new tissue entirely covering the human amniotic membrane plug. Visual acuity improved from 20/2000 (2 LogMAR) to 20/250 (1.1 LogMAR) 3 months after the operation in both patients. The silicone oil was extracted 2 months after surgery, and no recurrences were observed. The patient's visual acuity remained stable at 20/250 after the silicone oil extraction. In these complex cases, human amniotic membrane transplantation can be a valid option, when internal limiting membrane has already been peeled in previous surgeries, to seal the posterior retinal breaks over high myopic chorioretinal atrophy, with encouraging results.

Effect of Human Amniotic Membrane Transplantation in Reconstruction of Canine Corneal Wound

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 freeze-dried 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.

Antifibrotic Effects of Decellularized and Lyophilized Human Amniotic Membrane Transplant on the Formation of Intrauterine Adhesion.

Intrauterine adhesion is a disease involving endometrial fibrosis that arises from injury to the basal layer of the endometrium. Here, we aimed to explore the preventive effects of decellularized and lyophilized amniotic membrane on endometrial fibrosis in a rat model of intrauterine adhesion. Twenty-four Sprague-Dawley rats were randomly divided into 2 groups. For the intrauterine adhesion group, endometria of left uteri were scraped without treatment. For the intrauterine adhesion plus decellularized and lyophilized amniotic membrane transplant group, decellularized and lyophilized amniotic membrane was sutured onto the scraped wound of left uteri. Right uteri were kept as the control group. At 3, 7, 14, and 28 days after transplant, uteri were sampled for histologic and immunohistochemical evaluation. Histology examination revealed extensive fibrosis with significantly reduced numbers of endometrial glands in uteri in the intrauterine adhesion group. Immunohistochemical staining showed a remarked increase in expression of transforming growth factor β1 (P < .01) and decreased expression of matrix metalloproteinase-9 (P < .01) in the intrauterine adhesion group. In rats with transplant of decellularized and lyophilized amniotic membrane, endometrial fibrosis apparently improved (P < .05) with reduced expression of transforming growth factor β1 and increased matrix metalloproteinase-9 expression (P < .05). However, there were no significant differences in the number of endometrial glands or endometrial thickness between the 2 groups (P > .05). Development of intrauterine adhesion was prevented with transplant of decellularized and lyophilized amniotic membrane via suppression of transforming growth factor β1 and increased production of matrix metalloproteinase-9 in a rat model.

Long-term follow-up of cryopreserved amniotic membrane transplant during strabismus reoperations: Up 85 months' follow-up.

To evaluate the long-term effect of cryopreserved human amniotic membrane transplant during strabismus reoperations. A total of 15 patients with persistent strabismus were included in a prospective study to evaluate the effect of wrapping the extra-ocular muscles with cryopreserved amniotic membrane during strabismus reoperations. The study end-point was the last follow-up visit. A successful outcome was defined as 0-10∆ of horizontal tropia and 0-4∆ of vertical tropia, with no limitation of ductions exceeding -1. A cosmetically acceptable outcome was defined as a tropia of 0-15∆. Maximum follow-up was 85 months (mean: 25.4 ± 25.5 months). At the last follow-up visit, a successful outcome was achieved in 46.7%, a cosmetically acceptable outcome was achieved in 66.7%, and the mean ocular deviation angles improved from 38.60 ± 14.63∆, preoperatively, to 10.6 ± 11.08∆. Motility limitation on the final follow-up visit exceeded -1 in only 4/180 muscles (2.2%). The effect of cryopreserved amniotic membrane transplantation on the success of strabismus reoperations was moderate in terms of ocular alignment. Its effect was more pronounced in terms of ocular motility. The latter better reflects the level of adhesions. No long-term complications were documented, denoting safety of cryopreserved amniotic membrane usage during strabismus reoperations.

Transplantation of Human Amniotic Membrane over the Liver Surface Reduces Hepatic Fibrosis in a Cholestatic Model in Young Rats.

Purpose Biliary atresia precedes liver cirrhosis and liver transplantation. Amniotic membrane (AM) promotes tissue regeneration, inhibits fibrosis, and reduces inflammation. Here, we test amniotic membrane potential as a therapeutic tool against cholestatic liver fibrosis. Methods Three groups of rats were used: sham surgery (SS), bile duct ligature (BDL), and bile duct ligature plus human amniotic membrane (BDL + AM). After surgery, animals were sacrificed at different weeks. Biochemical and histopathological analyses of liver tissue were performed. Collagen was expressed as a percentage of total liver tissue area. qPCR was performed to analyse gene expression levels of transforming growth factor-β1 (Tgfb1) and apelin (Apln). Statistical analysis performed considered p < 0.05 was significant. Results Groups undergoing BDL developed cholestasis. Biochemical markers from BDL + AM group improved compared to BDL group. Ductular reaction, portal fibrosis, and bile plugs were markedly reduced in the BDL + AM group compared to BDL group. Collagen area in BDL + AM group was statistically decreased compared to BDL group. Finally, expression levels of both Apln and Tgfb1 mRNA were statistically downregulated in BDL + AM group versus BDL group. Conclusion AM significantly reduces liver fibrosis in a surgical animal model of cholestasis. Our results suggest that AM may be useful as a therapeutic tool in liver cirrhosis.

A comparative study of different amniotic membrane orientations during extraocular muscle surgery in rabbits

ABSTRACTPurpose: To histopathologically compare the effect of different orientations of cryopreserved human amniotic membrane (AM) transplant during extraocular muscle surgery in rabbits.Methods: Fifty-two albino rabbit eyes underwent 4-mm resection of the superior rectus. Eyes were randomly divided into four groups. In Group C (Control group, 16 eyes) the muscle was not wrapped with amniotic membrane. In the three AM groups, cryopreserved AM was wrapped around the muscle, oriented with either its stroma (Group S, 15 eyes) or epithelium (Group E, nine eyes) towards the muscle, or folded on itself with the epithelium externally (Group F, 12 eyes). The rabbits were sacrificed and the eyes were enucleated 6 weeks after surgery. Histopathological examination was conducted for periamniotic, foreign body, scleral, and conjunctival inflammation, conjunctival vascularity, adhesions and muscle fibrosis.Results: In all AM eyes, the AM was surrounded by periamniotic inflammation, with no adhesions detected between the muscle and surrounding tissues in the segment where the AM was present, but detected elsewhere. Adhesions were detected in all group C eyes. Foreign body inflammation was significantly less in Group C than in each of the AM groups (p < .05), but was insignificantly different among the three AM groups (p > .05). Scleral inflammation was absent in all specimens. No significant differences were noted among all groups in terms of conjunctival vascularity, conjunctival inflammation, or muscle fibrosis (p > .05).Conclusions: All AM orientations were equally effective in preventing the development of postoperative adhesions between the extraocular muscle and surrounding tissues.

A controlled study of the role of cryopreserved amniotic membrane transplant during strabismus reoperations

To evaluate the effects of using cryopreserved human amniotic membrane (AM) transplant during strabismus reoperations. A total of 30 patients with persistent strabismus were included in this prospective study. Patients were divided into two groups of 15 patients each. The AM group underwent strabismus reoperation with wrapping of the muscles with cryopreserved amniotic membrane. Controls underwent strabismus reoperation without an AM wrap. Final follow-up visit was scheduled between 3 and 12months postoperatively. Surgical success was defined as 0Δ-10Δ of horizontal tropia and 0Δ-4Δ of vertical tropia, with no limitation of ductions exceeding -1. A cosmetically acceptable outcome was defined as a tropia of 0Δ-15Δ. Three patients were excluded in the AM group due to incomplete follow-up. A successful outcome was achieved in 7 patients in each group (58% and 47% in groups AM and C, resp.; P=0.63). Acosmetically acceptable outcome was achieved in 10 patients in the AM group (83.3%) and 12 (80%) in the control group (P=0.48). The mean ocular deviation angles improved to 8.7Δ ± 12Δ in the AM group and 12.3Δ ± 17.4Δ in the control group (P=0.63). Ductions improved in 66.7% and 36.4% of the muscles with limited motility in groups AM and C, respectively (P=0.019). Wrapping the extraocular muscles with cryopreserved AM during strabismus reoperations was of limited clinical benefit. We attributed this to the small segment of AM used and to the presence of other causes of failure rather than adhesions.

Antifibrotic Effects of Human Amniotic Membrane Transplantation in Established Biliary Fibrosis Induced in Rats

Liver fibrosis is characterized by excessive accumulation of extracellular matrix components in the liver parenchyma that distorts the normal architecture and hepatic function. Progressive fibrosis could end in the advanced stage known as cirrhosis, resulting in the need to resort to liver transplantation. Amniotic membrane (AM) has emerged as an innovative therapeutic approach for chronic liver diseases due to its anti-inflammatory, antiscarring, and wound-healing effects. We have recently shown that AM can be used as a patch on the liver surface at the same time of fibrosis induction, resulting in significantly reduced progression and severity of biliary fibrosis. Here we investigated the effects of human AM on the established rat model of liver fibrosis, induced by the bile duct ligation (BDL). We also explored the effect of AM on the expression of transforming growth factor-1 (TGF-1), the main profibrogenic factor in hepatic fibrosis, and the proinflammatory cytokines, tumor necrosis factor- (TNF-), interleukin-6 (IL-6), and anti-inflammatory cytokine IL-10. Two weeks after BDL, the liver was covered with a fragment of AM or left untreated. Six weeks later, the fibrosis was first assessed by the semiquantitative Knodell and the METAVIR scoring systems and, thereafter, by CellProfiler digital image analysis to quantify the area occupied by collagen deposition, ductular reactions (DRs), activated myofibroblasts, and TGF-1. The hepatic cytokines were determined by ELISA. AM-treated rats showed a significantly lower score compared to the control BDL rats (2.50.9 vs. 3.50.3, respectively; p0.05). The collagen deposition, DRs, number of activated myofibroblasts, and TGF-1 were all reduced to about 50% of levels observed in untreated BDL rats. These findings suggest that AM, when applied as a patch onto the liver surface, is useful for treating well-established cholestatic fibrosis, and the mechanism was partly by means of downregulating the profibrotic factor TGF-1 and IL-6.

Human Amniotic Membrane Transplantation - Different Modalities of its Use in Ophthalmology

The amniotic membrane (AM) is the inner layer of the fetal membranes and consist of 3 different layers: the epithelium, basement membrane and stroma which further consists of three contiguous but distinct layers: the inner compact layer, middle fibroblast layer and the outermost spongy layer. The AM has been shown to have anti-inflammatory, anti-fibrotic, anti-angiogenic as well as anti-microbial properties. Also because of its transparent structure, lack of immunogenicity and the ability to provide an excellent substrate for growth, migration and adhesion of epithelial corneal and conjunctival cells, it is being used increasingly for ocular surface reconstruction in a variety of ocular pathologies including corneal disorders associated with limbal stem cell deficiency, surgeries for conjunctival reconstruction, as a carrier for ex vivo expansion of limbal epithelial cells, glaucoma surgeries and sceral melts and perforations. However indiscriminate use of human AM needs to be discouraged as complications though infrequent can occur. These include risk of transmission of bacterial, viral or fungal infections to the recipient if the donors are not adequately screened for communicable diseases, if the membrane is not processed under sterile conditions or if storage is improper. Optimal outcomes can be achieved only with meticulous case selection. This review explores the ever expanding ophthalmological indications for the use of human AM.

Histopathological evaluation of the healing effects of human amniotic membrane transplantation in third-degree burn wound injuries

Skin burn injuries result in loss of its protective function as a barrier and leading to a high risk of infection. Therefore, effective treatments and healing of burn injuries are very important to prevent complications. Amniotic membrane (AM) as a biological dressing inhibits the loss of vital fluids, water, and protein. The aim of this study was to compare the healing effects of AM and silver sulfadiazine (SSD) ointment in third-degree burn injuries in experimental rat model. Fifty-four male Sprague–Dawley rats were divided randomly into three equal groups. After induction of third-degree burn, transplantation of human AM (HAM) and SSD ointment used on wound area for treatment groups. The third group was considered as control. At days 7, 14, and 21, histopathological evaluation of burn wound area was performed using light microscopy. After 21 days, burn injury in HAM group showing lack of enough wound contraction and decrease in wound area in comparison to SSD group. Also, the healing effects were demonstrated using decline of inflammatory cell infiltration and enhanced epithelium after 21 days. The total wound score was significantly higher in the HAM group than the control and SSD ointment groups, during and at the end of the experiment (P < 0.05). On day 21, significantly lesser inflammatory cell infiltration was noticed in the control group (P < 0.05). Our findings showed that HAM can be used successfully as a biological treatment for experimental third-degree burn injury in animal model.

Long-term efficacy of glycerine-processed amniotic membrane transplantation in patients with corneal ulcer.

The aim of this study was to determine the long-term treatment efficacy of glycerine-preserved human amniotic membrane transplantation in patients suffering from corneal ulcers. This was a retrospective, non-controlled, monocentric analysis. Included were patients with corneal ulcers that were non-responsive to ointment or contact lenses and had been treated by amniotic membrane transplantation with either the overlay or sandwich procedure. Analysis parameters were visual acuity before and following treatment, recurrence rate and subjective comfort at the last follow-up. Of the 371 amniotic membrane transplantations that were conducted, 135 surgical treatments in 108 patients (51.9% male, 48.1% female; mean age 63.7 years) met the inclusion criteria. In total, 99 overlay and 36 multilayer amniotic membrane transplantations were performed. The follow-up period was 47.5 ± 66.7 weeks (mean ± SD). The recurrence rate at the last follow-up was 47.8% with overlay membranes and 51.8% with the sandwich technique. There was no significant change in best-corrected visual acuity following treatment with overlays (p = 0.219) or sandwich procedure (p = 0.703). At the last follow-up, 72.1% (overlay) and 78.3% (sandwich) of the patients reported either no pain or increased comfort. The recurrence rates and changes in visual acuity following overlay or sandwich amniotic membrane transplantation in patients suffering from corneal ulcer were lower than reported elsewhere in the literature. More than half of the patients profited from each of the amniotic membrane transplantation techniques with respect to recurrence and postoperative comfort.

Anti-neovascular effect of chondrocyte-derived extracellular matrix on corneal alkaline burns in rabbits.

We investigated the effect of a chondrocyte-derived extracellular matrix (CDECM) on experimental corneal alkaline burns in rabbits. Corneal neovascularization (NV) was induced by applying an 8-mm filter paper soaked in 1N NaOH to the right central corneas of rabbits for 1minute. Ten days later, the rabbits were randomly divided into three groups: the alkaline burn group, the CDECM transplantation group, and the human amniotic membrane (HAM) transplantation group. The left eyes were used as controls. CDECM and HAM were transplanted onto the corneal surface to completely cover the resected area and were subsequently sutured. On the 10th day after transplantation, the structural changes of the cornea were analyzed histologically. We examined the effects of CDECM on clinical NV features and on the expression of corneal NV markers. The alkaline burn produced significant NV and increased the corneal thickness. On day 10 after transplantation, the thickness, NV and opacity of the cornea were markedly decreased in the CDECM group (p < 0.001). However, the HAM transplantation group did not exhibit improvements in these clinical parameters, and there were no significant differences relative to the burn group. In addition, the use of CDECM improved the healing of the cornea following the alkaline burn by disrupting the corneal epithelial proliferation and reducing the fibrotic changes of the stroma. The hallmarks of NV were significantly induced in the subepithelium by the alkaline burn, and these levels were also suppressed by CDECM. The CDECM suppressed corneal NV by inhibiting nuclear factor-kappa B (NF-κB) activation by blocking the PKC and Akt signaling pathways. CDECM transplantation was markedly effective in healing alkali-burned corneas by modulating the translocation of NF-κB to the nucleus, thereby representing a promising material for the noninvasive treatment of ocular surface disease.

A skin substitute based on human amniotic membrane

Human amniotic membrane (HAM) has biological properties which are useful for wound healing. HAM is notably one of the therapeutic alternatives for venous leg ulcer care. Indeed, a prospective clinical study has demonstrated that cryopreserved HAM transplantation for leg ulcer is feasible, safe and has beneficial effects: 80 % of the patients had a significant clinical response. Nevertheless, at the end of the 3-month follow-up period, only 20 % of the ulcers were totally closed. The aim of this work was to create and characterize a model of epidermized HAM. The method of HAM desepithelialization was validated by histology, immunohistochemistry and scanning electron microscopy. Then, de-epithelialized HAM was seeded with primary keratinocytes. After 21 days of culture, 15 at the air-liquid interface, the model obtained was analyzed histologically and by immunohistochemistry. The amniotic basement membrane was preserved during enzymatic desepithelialization of HAM. Primary keratinocytes proliferated on HAM: the model obtained showed involucrin expression and had a good basement membrane. As re-epithelialization is an important step for ulcer closure, a model of epidermized HAM could be used to speed up the healing of such wounds.

Human amniotic membrane transplantation: Different modalities of its use in ophthalmology.

The amniotic membrane (AM) is the inner layer of the fetal membranes and consist of 3 different layers: the epithelium, basement membrane and stroma which further consists of three contiguous but distinct layers: the inner compact layer, middle fibroblast layer and the outermost spongy layer. The AM has been shown to have anti-inflammatory, anti-fibrotic, anti-angiogenic as well as anti-microbial properties. Also because of its transparent structure, lack of immunogenicity and the ability to provide an excellent substrate for growth, migration and adhesion of epithelial corneal and conjunctival cells, it is being used increasingly for ocular surface reconstruction in a variety of ocular pathologies including corneal disorders associated with limbal stem cell deficiency, surgeries for conjunctival reconstruction, as a carrier for ex vivo expansion of limbal epithelial cells, glaucoma surgeries and sceral melts and perforations. However indiscriminate use of human AM needs to be discouraged as complications though infrequent can occur. These include risk of transmission of bacterial, viral or fungal infections to the recipient if the donors are not adequately screened for communicable diseases, if the membrane is not processed under sterile conditions or if storage is improper. Optimal outcomes can be achieved only with meticulous case selection. This review explores the ever expanding ophthalmological indications for the use of human AM.