Freeze-dried Amniotic Membrane Research Articles

A Biosynthetic Alternative to Human Amniotic Membrane for Use in Ocular Surface Surgery.

The biosynthetic Symatix membrane (SM) was developed to replace fresh human amniotic membrane (hAM) in ocular surgical applications. The purpose of this study was to test the biocompatibility of the SM with human limbus-derived epithelial cells with regard to their physical and biological properties. Different physical properties of SM were tested ex vivo by simulation on human corneas. In vitro, primary limbal epithelial cells from limbal explants were used to test biological properties such as cell migration, proliferation, metabolic activity, and limbal epithelial cell markers on the SM, hAM, and freeze-dried amniotic membrane (FDAM). The surgical handleability of the SM was equivalent to that of the hAM. Ultrastructural and histological studies demonstrated that epithelial cells on the SM had the typical tightly apposed, polygonal, corneal epithelial cell morphology. The epithelial cells were well stratified on the SM, unlike on the hAM and FDAM. Rapid wound healing occurred on the SM within 3days. Immunofluorescence studies showed positive expression of CK-19, Col-1, laminin, ZO-1, FN, and p-63 on the SM, plastic, and FDAM compared to positive expression of ZO-1, Col-1, laminin, FN, and p63 and negative expression of CK-19 in the hAM. These results indicate that the SM is a better substrate for limbal epithelial cell migration, proliferation, and tight junction formation. Altogether, the SM can provide a suitable alternative to the hAM for surgical application in sight-restoring operations. The hAM, currently widely used in ocular surface surgery, has numerous variations and limitations. The biocompatibility of corneal epithelial cells with the SM demonstrated in this study suggests that it can be a viable substitute for the hAM.

EFFECTIVENESS AND SAFETY OF AMNIOTIC MEMBRANE GRAFTING FOR CORNEAL SURFACE DISORDER: A RANDOMIZED CLINICAL STUDY

Objective: The aim of the study was to evaluate the effectiveness and safety of freeze-dried amniotic membrane grafting (AMG) and compare it against traditional medical therapy for the management of corneal surface disorders. Methods: A randomized clinical trial was conducted on 60 patients with corneal surface disorders who were randomized equally either into the AMG group (n=30) or medical management group (n=30). Patients in both groups were followed up for 8 weeks after receiving group-specified intervention or till complete resolution (whichever was earlier). Treatment outcome, healing time, improved vision, decreased pain, recurrence rate, and corneal clarity were the main outcome metrics. Results: The most common corneal disorder was persistent epithelial defect (38.33%), closely followed by impending perforated corneal ulcer (31.66%). Majority of the patients (36.66%) had corneal involvement of >75%, while 31.66% had involvement ranging from 50 to 75%. The success rate of AMG (96.7%) was significantly higher than that of medical management (76.7%) in the treatment of corneal surface disorders (p=0.022). During the follow-up period, the incidence of allergic reactions was slightly lower in the AMG group (6.7%) compared to the medical management group (10.0%). Overall, the incidence of side effects and other complications was low in both the AMG group and the medical management group. The severity of side effects was comparable in both the study groups (p=0.886). The recurrence rate of corneal surface disorders in the in the AMG group (6.7%) was statistically lower than that in the medical management group (26.7%) (p=0.037). Conclusion: The findings of the present study supported the use of AMG as an effective and safe alternative to medical management for the treatment of conditions affecting the corneal surface.

A biosynthetic alternative to human amniotic membrane for cornea repair—A comparative in‐vitro study

Aims/Purpose: We hypothesize that the biosynthetic Symatix membrane (SM) can replace human amniotic membrane (HAM) in ocular surgical applications. Our aim was to test this hypothesis by comparing the performance of limbal epithelial cells (LECs) cultures on the membranes.Methods: SM was manufactured by the Electrospinning Company Ltd using its proprietary Symatix® Technology platform. SM consists of degradable medical grade poly (lactic‐co‐glycolic acid) polymer fibres and sodium hyaluronan. The suturing and fibrin gluing of SM were tested ex‐vivo by simulation on human corneas. LECs from human limbal tissue were used for testing cellular properties namely cell proliferation (scratch wound and Ki‐67 assay), metabolic activity, limbal epithelial cell marker (cytokeratin‐19 (CK‐19)) tight junction formation (zonula occludens‐1 (ZO‐1)), cell‐ECM interaction (fibronectin (FN)), and basement membrane protein expression (laminin) on SM, plastic, HAM, and freeze‐dried amniotic membrane (FDAM).Results: The surgical handleability of SM was equivalent to HAM. Histological studies demonstrated that epithelial cells on SM had the typical tightly apposed, polygonal, corneal epithelial cell morphology. Rapid wound healing occurred on SM within 3 days; Ki‐67 revealed increased progressive proliferation; and improved metabolic activity was found on SM compared to HAM and FDAM. Immunofluorescence studies showed positive expression of CK‐19, collagen‐1 (Col‐1), laminin, ZO‐1, and FN in SM, plastic, and FDAM compared to negative expression of CK‐19 and ZO‐1 and positive expression of collagen‐1 (Col‐1), laminin and FN in HAM. This could indicate that SM is a better substrate for epithelial cell migration, proliferation, and tight junction formation.Conclusions: This data demonstrates that SM can provide a suitable alternative to HAM for surgical application in sight‐restoring operations.

Freeze-dried amniotic membrane graft with a spongy layer in bilateral peripheral ulcerative keratitis: a case report

BackgroundPeripheral ulcerative keratitis (PUK) is a group of inflammatory corneal ulcers with stromal thinning and peripheral localization. Amniotic membranes (AM) are used for their anti-inflammatory and healing properties. A freeze-drying process now allows maintaining the AM viable for a long time at room temperature without altering its physical, biological, and morphologic characteristics. The effectiveness of spongy freeze-dried amniotic membrane (FD-AM) graft with multimodal imaging in the management of severe corneal thinning PUK has not been reported.Case presentationA 67-year-old Caribbean man histologically diagnosed with ulcerative colitis, was referred to our tertiary eye care center for a deep nasal juxtalimbal ulcer of the left eye. He was treated with topical steroids and antibiotics, methylprednisolone pulses, and oral prednisone. Due to continuous stromal thinning with 100 μm of residual corneal thickness, the decision was made to perform surgery. Conjunctival resection, inlay and overlay spongy FD-AM (Visio Amtrix® S, Tissue Bank of France, FR) were performed to preserve globe integrity. Despite tapering off oral steroids, PUK developed in the fellow eye on the 2 months follow-up. Treatment with human monoclonal antibody against tumor necrosis factor-alpha was initiated to control the active underlying inflammation. Six months following surgery, the ulcer was healed and corneal thickness in front of the former ulceration was measured at 525 μm on anterior segment-optical coherence tomography. Confocal microscopy confirmed the integration of the amniotic membrane between the corneal epithelium and the anterior stroma.ConclusionTransplantation of FD-AM with a spongy layer was associated with restoration of normal corneal thickness in the PUK area. It seems to be a safe, effective, and easily accessible solution for the surgical management of PUK with impending perforation.

Quantification of Analgesic and Anti-Inflammatory Lipid Mediators in Long-Term Cryopreserved and Freeze-Dried Preserved Human Amniotic Membrane.

The aim of this study was to compare concentrations of endogenous N-acylethanolamine (NAE) lipid mediators-palmitoylethanolamide (PEA), oleoylethanolamide (OEA), and anandamide (AEA)-in fresh, decontaminated, cryopreserved, and freeze-dried amniotic membrane (AM) allografts, thereby determining whether AM's analgesic and anti-inflammatory efficiency related to NAEs persists during storage. The concentrations of NAEs were measured using ultra-high-performance liquid chromatography-tandem mass spectrometry. Indirect fluorescent immunohistochemistry was used to detect the PEA PPAR-α receptor. The concentrations of PEA, OEA, and AEA were significantly higher after decontamination. A significant decrease was found in cryopreserved AM compared to decontaminated tissue for PEA but not for OEA and AEA. However, significantly higher values for all NAEs were detected in cryopreserved samples compared to fresh tissue before decontamination. The freeze-dried AM had similar values to decontaminated AM with no statistically significant difference. The nuclear staining of the PPAR-α receptor was clearly visible in all specimens. The stability of NAEs in AM after cryopreservation was demonstrated under tissue bank storage conditions. However, a significant decrease, but still higher concentration of PEA compared to fresh not decontaminated tissue, was found in cryopreserved, but not freeze-dried, AM. Results indicate that NAEs persist during storage in levels sufficient for the analgesic and anti-inflammatory effects. This means that cryopreserved AM allografts released for transplant purposes before the expected expiration (usually 3-5 years) will still show a strong analgesic effect. The same situation was confirmed for AM lyophilized after one year of storage. This work thus contributed to the clarification of the analgesic effect of NAEs in AM allografts.

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

BackgroundLocoregional stem cell delivery is very important for increasing the efficiency of cell therapy. Amnisite BA (Amnisite) is a freeze-dried amniotic membrane harvested from bovine placenta. The objective of this study was to investigate the retention of cells of the stromal vascular fraction (SVF) on Amnisite and to determine the effects of cell-loaded Amnisite in a porcine radiation-induced chronic wound model.MethodsInitially, experiments were conducted to find the most suitable hydration and incubation conditions for the attachment of SVF cells extracted from pig fat to Amnisite. Before seeding, SVFs were labeled with PKH67. The SVF cell-loaded Amnisite (group S), Amnisite only (group A), and polyurethane foam (group C) were applied to treat radiation-induced chronic wounds in a porcine model. Biopsy was performed at 10, 14, and 21 days post-operation for histological analysis.ResultsRetaining the SVF on Amnisite required 30 minutes for hydration and 1 hour for incubation. A PKH67 fluorescence study showed that Amnisite successfully delivered the SVF to the wounds. In histological analysis, group S showed increased re-epithelialization and revascularization with decreased inflammation at 10 days post-operation.ConclusionsSVFs had acceptable adherence on hydrated Amnisite, with successful cell delivery to a radiation-induced chronic wound model.

Freeze-dried Amniotic Membrane (FD-AM) Application to Fibroblast Growth Factor Expression on Urethral Defect Reconstruction in New Zealand White Rabbit (Oryctolagus cuniculus)

Freeze-dried Amniotic Membrane (FD-AM) Application to Fibroblast Growth Factor Expression on Urethral Defect Reconstruction in New Zealand White Rabbit (Oryctolagus cuniculus)

Corrigendum: A randomized clinical trial of freeze-dried amniotic membrane transplantation and conjunctival-limbal graft for pterygium excision and evaluation of conjunctival inflammation marker in tears

[This corrects the article DOI: 10.13181/mji.oa.203818]

Dose-dependent pro- or anti-scar-preventing responses of freeze-dried amniotic membrane extract in relation to suppression of connective tissue growth factor and α-smooth muscle actin

Dose-dependent pro- or anti-scar-preventing effects of amniotic membrane extract (AME) are unclear. This study investigated the dose-dependent effects of freeze-dried AME on connective tissue growth factor (CTGF) and α-smooth muscle action (α-SMA) (key determinants of excessive scarring) expression in an attempt to develop medication for scarless wound healing. The inhibitory effect of freeze-dried AME on α-SMA was visualized through immunofluorescence confocal microscopy. The suppressive effect of 10 different concentrations of AME (0.0025–0.25 µg/mL) on CTGF and α-SMA was determined, and rates of collagen lattice contraction were measured. AME inhibited the trans-differentiation of fibroblasts to myofibroblasts, a hallmark of scar formation. AME downregulated CTGF and α-SMA in a dose-dependent manner; supplementation of 0.0175 µg/mL of AME in cell culture media downregulated CTGF (by 49%; p < 0.05) and α-SMA (by 33%; p < 0.05) relative to control values, the effect saturating with a subsequent increase in AME levels to 0.025 µg/mL. Collagen lattice contraction was maximally inhibited (75 ± 8%) upon treatment with 0.0175 µg/mL AME relative to the control (44 ± 6%). AME downregulates α-SMA and inhibits the trans-differentiation of fibroblasts to myofibroblasts in a dose-dependent manner. Treatment of cells with high AME concentrations retained high α-SMA concentration levels. A delicate balance between the wound healing properties and pro-fibrotic abilities of AME should be considered for selecting an appropriate therapeutic dose.

A randomized clinical trial of freeze-dried amniotic membrane transplantation and conjunctival-limbal graft for pterygium excision and evaluation of conjunctival inflammation marker in tears

BACKGROUND Minimizing inflammation on the ocular surface after pterygium surgery is essential to prevent recurrence. Currently, limited data are available for the comparison between freeze-dried amniotic membrane (FD-AM) and conjunctival–limbal graft (CLG). Therefore, this study aimed to assess conjunctival inflammation and the interleukin (IL)-6 levels in tears after pterygium excision between both techniques.&#x0D; METHODS This prospective, single-blinded, randomized clinical trial included 26 eyes of 26 patients with primary or recurrent pterygium and who were indicated for pterygium surgery at Cipto Mangunkusumo Hospital, Indonesia from October 2017 until February 2018. The patients were scheduled for pterygium excision with FD-AM or CLG based on block randomization. Conjunctival inflammation and the level of IL-6 in tears were measured on day-7 and -28 after surgery.&#x0D; RESULTS The 26 eyes (13 in each group) were subjected to a complete 1-month follow-up period. Day-7 after the surgery, severe inflammation occurred in 4/13 (31%) eyes having FD-AM and 8/13 eyes (62%) having CLG (p = 0.59). The IL-6 tear level increased similarly in FD-AM (22.85 pg/ml) and CLG (23.51 pg/ml) in (p = 0.78). No severe adverse events occurred.&#x0D; CONCLUSIONS Pterygium excision using FD-AM yield a milder inflammation than CLG on day-7 and -28 after surgery. The tear IL-6 levels similarly increased on day-7.

Cytotoxicity test for the use of freeze-dried amniotic membranes against viability, proliferation, and apoptosis on brain cell culture: An in vitro study

ObjectiveThis study aimed to conduct a cytotoxicity test in determining biocompatibility of freeze-dried amniotic membranes on brain cell culture. MethodsAn in vitro study was carried out on rat’s brain cell culture. Samples were divided into three groups: control, conditioned medium, and direct amniotic membrane exposure. Each group was stained with MTT, DAPI and Annexin-V for its viability, proliferation, and apoptosis, respectively. Statistical analysis was conducted using ANOVA, post-hoc, or the Kruskal-Wallis test with CI 95%. ResultsViability test using MTT staining showed viable cell in conditioned medium group of 76.99±10.19, and direct amniotic membrane exposure group of 90.36±23.31 (p=0.001). DAPI staining showed a median value of 5.32 (1.97-16.53) for control group, 6.00 (2.42-16.62) for conditioned medium group, and 3.53 (1.32-8.69) for direct amniotic membrane exposure. Annexin-V single staining showed mean value of 10.28±2.43 (control group), 10.07±0.97 (conditioned medium), and 10.42±4.07 (direct amniotic membrane; p=0.969). Double staining by Annexin V + DAPI showed mean value of 10.43±1.82 (control), 10.01±1.07 (conditioned medium), and 12.40±3.67 (direct amniotic membrane exposure; p=0.148). ConclusionAmniotic membrane exposure affected rat’s brain cell culture viability in tolerable limit, while proliferation and apoptosis do not get affected.

Effect of Amniotic Membrane-Derived Mesenchymal Stem Cells on TNF-? Expression and Inflammatory Cells Infiltration during Vesicovaginal Fistule Repair Healing Process

Background: Vesicovaginal fistula (VVF) causes high morbidity in women, affecting both physical and psychological condition. Until now, surgery is the mainstay treatment for this condition. However, prolonged exposure during inflammatory phase after surgery is still a problem in the healing process. TNF-α as potent pro-inflammatory cytokine plays an important role by attracting inflammatory cells to wound tissue. Amniotic membrane is the source for mesenchymal stem cells that had anti-inflammatory and imunomodulatory effect. This study aims to evaluate the effect of Amniotic Membrane-Derived Mesenchymal Stem Cells (AMMSC) on TNF-α expression and inflammatory cell infiltration during VVF repair healing process in New Zealand White (NZW) rabbit model. Method: This study was an experimental study with randomized posttest only control group design. Twentyseven NZW rabbit as VVF model was used in this study, randomly divided into 3 different treatment groups after underwent surgical treatment (no treatment , treated with freeze-dried amniotic membrane , and treated with freeze-dried amniotic membrane that seeded with AMMSC ). Evaluation was done 7 days after treatment. TNF-α expression was evaluated semiquantitatively using modified Remmele-Stegner scale. Inflammatory cell infiltration was evaluated using modified Klopfleisch method. Results: Mean TNF-α expression between C, T1, and T2 group were significantly different (8.5 ± 1.6; 7.1 ± 1.2; 1.6 ± 1.2 respectively, p < 0.001). Median inflammatory cell infiltration between C, T1, and T2 group were significantly different (3.0; 2.0; 1.0 respectively, p < 0.001). Conclusion: AMMSC significantly reduced TNF-α expression and inflammatory cells infiltration during VVF repair healing process.

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.

Different Light Transmittance of Placental and Reflected Regions of Human Amniotic Membrane That Could Be Crucial for Corneal Tissue Engineering.

Because of long-term incorporation of amniotic membrane (AM) into corneal stroma after transplantation as a scaffold for stem cell delivery, the variation in haziness is a major factor that influences visual quality. The aim of this study was to evaluate probable sources of transparency variation in fresh and freeze-dried AM and compare the obtained results with transparency of rabbit corneas. Amnions were extracted from placental and reflected regions of placentas from elective Cesarean sections. The effects of removing epithelial cells and spongy layer on transparency and thickness of fresh and freeze-dried AMs and rabbit cornea were evaluated. The epithelial surface of AMs was evaluated with histological analysis and scanning electron microscopy. The reflected region of intact AM was thinner and more transparent than the placental region. From histological analysis, the main source of difference between placental and reflected regions of amnion is related to epithelial cells. The process of acellularization improved light transmission of the AM in both placental and reflected regions and also omitted variation between transparency of reflected and placental regions of AM. Freeze-drying of intact AM did not improve transparency because of scattering of light by cellular debris; however, removing the epithelial layer before freeze-drying resulted in optimized light transmission similar to transparency of rabbit cornea. The amniotic epithelial cells play a major role as a source of variation in light transmission properties of amnion. From the results, epithelial-denuded freeze-dried AM was found to be a suitable scaffold to be applied in corneal tissue engineering.

Efficacy and safety of the use of freeze-dried (lyophilized) amniotic membrane transplantation with combined trabeculotomy-trabeculectomy for congenital glaucoma

Purpose The aim of the study was to evaluate the outcome of the surgical technique that utilizes freeze-dried (lyophilized) amniotic membrane transplantation (AMT) with combined trabeculotomy-trabeculectomy in cases of primary congenital glaucoma with respect to its efficacy and complications. Patients and methods This was a prospective controlled study that included 25 eyes of 19 patients with primary congenital glaucoma. The patients were categorized into two groups: group I included 14 eyes that were treated with combined trabeculotomy-trabeculectomy with AMT and group II included 11 eyes that were treated with combined trabeculotomy-trabeculectomy without adjunctive (control group). Results Nineteen patients were included in the study: 13 were male and six were female. The mean age was 6.2 ± 3.5 months and 5.7 ± 2.9 months in groups I and II, respectively; there were no statistically significant differences between groups I and II regarding the patient demographics and preoperative characteristics. The surgical outcome of the two groups showed that absolute success was achieved in 71.4% and qualified success in 14.3% in group I, and in group II absolute success was achieved in 45.5% and qualified success in 27.2%. This difference was highly significant in terms of absolute success and significant in terms of total success between the two groups. The mean intraocular pressure (IOP) in this study was markedly decreased from preoperative values in both groups during postoperative follow-up visits, with statistically significantly lower IOP in group I than in group II at all postoperative visits. The complications encountered were hyphema in 28.6% of patients in group I and in 27.3% of patients in group II. Shallow anterior chamber associated with hypotony occurred in 21.4 and 18.2% of patients in groups I and II, respectively. One case in each group developed serous choroidal detachment. Flat nonfunctioning bleb with high IOP occurred in 14.3% of patients in group I and in 27.3% in group II. The complication rates were statistically insignificant between the two groups. Conclusion AMT-enhanced combined trabeculotomy-trabeculectomy appears to be an effective procedure for the treatment of primary congenital glaucoma with better long-term control of IOP and without added complications.

Freeze-dried amniotic membrane transplantation for ocular surface diseases

Objective To evaluate the efficacy of freeze-dried amniotic membrane transplantation for ocular surface diseases.Methods Retrospectively summarized freeze-dried amniotic membrane transplantation in 79 eyes of 72 patients with ocular surface diseases,and the clinical effect was evaluated.Results The amniotic membranes were alive and attached well in 75 eyes (94.9％).The therapeutic effect was satisfactory.Conclusion Freeze-dried amniotic membrane transplantation can be used for the treatment of ocular surface diseases. Key words: Membrane, amniotic, freeze-dried; Transplantation; Diseases,ocular surface

The effects of preservation procedures on antibacterial property of amniotic membrane

Amniotic membrane (AM), the innermost layer of the fetal membranes, has been widely employed in the surgical reconstruction and tissue engineering. Expression of the antimicrobial peptides such as defensins, elafin and SLPI which are essential elements of the innate immune system results in antibacterial properties of the AM. Preservation is necessary to reach a ready-to-use source of the AM. However, these methods might change the properties of the AM. The aim of this study was to evaluate antibacterial properties of the AM after preservation. Antibacterial property of the fresh AM was compared with cryopreserved and freeze-dried AM by modified disk diffusion method. Staphylococcus aureus ATCC 25923, Pseudomonas aeruginosa ATCC 27853, Escherichia coli ATCC 25922 and two clinical isolated strains of E. coli were cultured in Mueller Hinton agar and a piece of the AM was placed on agar surface. After 24h incubation, the inhibition zone was measured. In addition, one of the most important antibacterial peptides, elafin, was measured by ELISA assay before and after preservations procedures. Antibacterial properties of the AM were maintained after cryopreservation and freeze-drying. However, the inhibition zone was depending on the bacterial strains. The cryopreservation and freeze-drying procedures significantly decreased elafin which shows that antibacterial property is not limited to the effects of amniotic cells and the other components such as extracellular matrix may contribute in antibacterial effects. The promising results of this study show that the preserved AM is a proper substitute of the fresh AM to be employed in clinical situations.

Hyperdry human amniotic membrane is useful material for tissue engineering: Physical, morphological properties, and safety as the new biological material

Human amniotic membrane (AM) has been used widely as graft biomaterial for a variety of clinical applications. But, there are some persistent problems related to the preparation, storage, and sterilization. To resolve these problems, we developed hyperdry AM (HD-AM) using far-infrared rays, depression of air, and microwaves and then sterilized by γ-ray irradiation. To elucidate the benefit of HD-AM as biological materials, compare with the physical and histological properties of HD-AM with a freeze-dried AM (FD-AM) as typical freeze-dried methods, evaluate the safety of HD-AM in vivo experiment used nude mice, and demonstrate the feasibility of HD-AM transplant in pterygium. The water permeability and the sieving coefficient of HD-AM were significantly lower than that of FD-AM. HD-AM has kept the morphological structure of epithelium and connective tissues. At 18 months after transplanted, single and multilayers of HD-AM in the intraperitoneal cavity was degraded without any infiltrated cells. For clinical treatment, recurrence of pterygium and regrowth of the subconjunctival fibrosis were not observed during the 6-month follow-up periods after the surgery. It was proposed that HD-AM was a safe and effective new biological material for clinical use including treatment for recurrent pterygium.

A freeze-dried (lyophilized) amniotic membrane transplantation with mitomycin C and trabeculectomy for pediatric glaucoma

Purpose: To evaluate the potential usefulness of a freeze-dried (lyophilized) amniotic membrane transplantation with mitomycin C (MMC) in the maintenance of functioning glaucoma surgery in cases of pediatric glaucoma.Methods: Thirty eyes of pediatric patients with glaucoma were included in this study. Trabeculectomy with amniotic membrane implantation and MMC was done in group 1 (15 eyes), and trabeculectomy with MMC only was done in group 2 (15 eyes). The preserved amniotic membrane was placed over the scleral flap and under the conjunctiva. The mean intraocular pressure (IOP) was measured pre- and postoperatively and bleb appearance was noted. The follow-up time was 18 months after surgery.Results: The mean postoperative IOP was significantly decreased to 15 ± 1 mm Hg and 17.2 ± 2.9 mm Hg in the 2 groups, respectively. The bleb was functioning well in the follow-up period in most of the cases, except 5 cases that needed another surgery. Complications such as inflammation, choroidal detachment, or toxic keratopathy were not noted in group 1 but were noted in group 2.Conclusion: Trabeculectomy with amniotic membrane transplantation and MMC can effectively control the elevated IOP in pediatric patients with glaucoma without significant postoperative complications.

Implantation of amniotic membrane to reduce postlaminectomy epidural adhesions

Postlaminectomy epidural adhesion is implicated as a main cause of "failed back surgery syndrome" and associated with increased risk of complications during revision surgery. Various materials acting as mechanical barriers to reduce fibroblasts infiltration into epidural space have met with limited success. In present research, amniotic membrane (AM) was studied to investigate its effects on reducing epidural scar adhesion after laminectomy in a canine model. Laminectomy sites were created at L-1, L-3, L-5, and L-7 levels in 24 adult mongrel dogs. Freeze dried AM (FAM), cross-linked AM (CAM), and autologous free fat (AFF) were implanted, respectively, at a randomly assigned site in each dog with the remaining untreated site serving as internal control. The animals were sacrificed at 1, 6, and 12 weeks postoperatively. Then, gross pathologic observation including scar amount and adhesion tenacity, qualitative histology evaluation, and quantitative histology analysis were compared. Gross observation demonstrated that scar amount and adhesion tenacity of CAM group were significantly lower in comparison with those of FAM and non-treatment groups. A white, slightly vascularized CAM layer covered the dura mater without tenacious scar adhesion. The histology analysis also indicated reduced fibroblasts infiltration and consequent epidural fibrosis, which were similar to the results of AFF group. In conclusion, the CAM is effective in reducing epidural fibrosis and scar adhesion after laminectomy in canine model. It is a promising biomaterial for future clinical applications.