Amniotic membrane transplantation for persistent epithelial defects with ulceration

Regeneration of corneal epithelium utilizing a collagen vitrigel membrane in rabbit models for corneal stromal wound and limbal stem cell deficiency

PURPOSE

This study was performed to evaluate the potential of a collagen-based membrane, collagen vitrigel (CV), for reconstructing corneal epithelium in the stromal wound and limbal stem cell deficiency (LSCD) models.

METHODS

Three groups of rabbits were used in the stromal wound model: CV affixed using fibrin glue (CV + FG group, n = 9), fibrin glue only (FG group, n = 3) and an untreated control group (n = 3). In the LSCD model, one group received CV containing human limbal epithelial cells (CV + hLEC group, n = 2) and the other was an untreated control (n = 1). Gross observation, including fluorescent staining, pathological examination, immunohistochemistry and electron microscopy, was used to evaluate the effect of CV on the corneal epithelium.

RESULTS

In the stromal wound model, fluorescent staining showed that epithelial reconstruction occurred as rapidly in the CV + FG group as it did in the control group. The pathological examination proved that the CV supported a healthy corneal epithelium in the CV + FG group, whereas FG led to hypertrophy and inappropriate differentiation of corneal epithelium in the FG group. In the LSCD model, the corneas in the CV + hLEC group showed sustained tissue transparency with good epithelialization, low inflammatory response and reduced neovascularization. However, the control cornea was translucent and showed high amounts of inflammation and neovascularization.

CONCLUSION

We have demonstrated that CV supports corneal epithelial differentiation and prevents epithelial hypertrophy, in addition to serving as a scaffold for hLEC transplantation, without complications.

Peptide therapies for ocular surface disturbances based on fibronectin-integrin interactions

The condition of the corneal epithelium is a critical determinant of corneal transparency and clear vision. The corneal epithelium serves as a barrier to protect the eye from external insults, with its smooth surface being essential for its optical properties. Disorders of the corneal epithelium include superficial punctate keratopathy, corneal erosion, and persistent epithelial defects (PEDs). The prompt resolution of these disorders is important for minimization of further damage to the cornea. Currently available treatment modalities for corneal epithelial disorders are based on protection of the ocular surface in order to allow natural healing to proceed. PEDs remain among the most difficult corneal conditions to treat, however. On the basis of characterization of the pathobiology of PEDs at the cell and molecular biological levels, we have strived to develop new modes of treatment for these defects. These treatments rely on two key concepts: provision of a substrate, such as the adhesive glycoprotein fibronectin, for the attachment and migration of corneal epithelial cells, and activation of these cells by biological agents such as the combination of substance P and insulin-like growth factor-1 (IGF-1). Central to both approaches is the role of the fibronectin-integrin system in corneal epithelial wound healing. Determination of the minimum amino acid sequences required for the promotion of corneal epithelial wound closure by fibronectin (PHSRN) and by substance P (FGLM-amide) plus IGF-1 (SSSR) has led to the development of peptide eyedrops for the treatment of PEDs that are free of adverse effects of the parent molecules.

Long-term symptomatic relief of bullous keratopathy with amniotic membrane transplant

The purpose of this study was to assess the long-term outcome of patients with symptomatic bullous keratopathy after amniotic membrane transplant. A retrospective cohort study includes that 20 patients with symptomatic bullous keratopathy, who have underwent amniotic membrane transplant at the Department of Ophthalmology & Visual Sciences, The Chinese University of Hong Kong, Prince of Wales Hospital & Alice Ho Miu Ling Hospital, Hong Kong between 04/1998 and 06/2011, were invited back. Clinical examination was performed, including, pain score assessment (pain score out of 10), epithelial healing, and vision. A total of 21 eyes of 20 patients returned for our study. The majority of eyes experienced pain reduction (94 %), with a significant mean pain score difference of 6.8 ± 2.6, 2-tail p < 0.001 (99 % CI 4.9-8.7). The mean pre-operative and post-operative pain scores were 7.3 ± 2.9 and 0.5 ± 1.0, respectively. 16 eyes (76 %) were completely pain free, and 10 eyes (47 %) remained symptom free after a mean follow-up of 39.0 ± 36.3 months (range 5-171 months). The median epithelial healing time was 2 weeks (range 1-20 weeks). Amniotic membrane transplant may be considered as a longer-term treatment for bullous keratopathy patients, especially in patients with poorer visual prognosis, but it may also be used as an interim measure for patients awaiting corneal transplant.

Postoperative changes in amniotic membrane as a carrier for allogeneic cultured limbal epithelial transplantation

PURPOSE

To investigate the morphologic changes and outcomes of the amniotic membrane as a carrier for allogeneic cultivated limbal epithelial transplantation.

DESIGN

Prospective, noncomparative, interventional study.

METHODS

A total of 16 eyes receiving allogeneic cultivated limbal epithelial transplantation with amniotic membrane as a carrier were enrolled. Morphologic changes in the amniotic membrane were observed by confocal microscopy and RTVue optical coherence tomography. The paired t test was employed to compare the mean best corrected visual acuity (BCVA) and corneal stromal thickness.

RESULTS

Of the 16 eyes, 12 had stable ocular surfaces (group A), while the other 4 eyes had failed surgeries due to immune rejection (group B). Confocal microscopy showed residual amniotic membrane tissues in 8 eyes in group A at 1 year. However, the amniotic membrane was not detected in group B at 8-10 months. RTVue optical coherence tomography showed discontinuous amniotic membrane tissues in all eyes in group A at 1 year, while highly reflective opacity was seen in the corneal stroma in group B. There were no statistically significant differences in mean BCVA and corneal stromal thickness in group A at 1 month and 1 year after transplantation (P > 0.05), but the mean BCVA showed a statistically significant difference at 1 month and after the disappearance of the amniotic membrane in group B (P < 0.05).

CONCLUSIONS

For eyes with stable ocular surfaces after cultivated limbal epithelial transplantation, the amniotic membrane can be present in the cornea for at least 1 year, with no impact on visual acuity or corneal stromal thickness. Chronic inflammation and neovascularization on the ocular surface may accelerate the disappearance of the amniotic membrane.

Xenogeneic acellular conjunctiva matrix as a scaffold of tissue-engineered corneal epithelium

Amniotic membrane-based tissue-engineered corneal epithelium has been widely used in the reconstruction of the ocular surface. However, it often degrades too early to ensure the success of the transplanted corneal epithelium when treating patients with severe ocular surface disorders. In the present study, we investigated the preparation of xenogeneic acellular conjunctiva matrix (aCM) and evaluated its efficacy and safety as a scaffold of tissue-engineered corneal epithelium. Native porcine conjunctiva was decellularized with 0.1% sodium dodecyl sulfate (SDS) for 12 h at 37°C and sterilized via γ-irradiation. Compared with native conjunctiva, more than 92% of the DNA was removed, and more than 90% of the extracellular matrix components (glycosaminoglycan and collagen) remained after the decellularization treatment. Compared with denuded amniotic membrane (dAM), the aCM possessed favorable optical transmittance, tensile strength, stability and biocompatibility as well as stronger resistance to degradation both in vitro and in vivo. The corneal epithelial cells seeded on aCM formed a multilayered epithelial structure and endured longer than did those on dAM. The aCM-based tissue-engineered corneal epithelium was more effective in the reconstruction of the ocular surface in rabbits with limbal stem cell deficiency. These findings support the application of xenogeneic acellular conjunctiva matrix as a scaffold for reconstructing the ocular surface.

Complications related to a cosmetic eye-whitening procedure

PURPOSE

To report sight-threatening complications following extensive bulbar conjunctival resection and postoperative mitomycin C therapy for cosmetic eye-whitening in the United States.

DESIGN

Retrospective noncomparative case series.

METHODS

Multicenter report of 9 patients referred for evaluation and management of complications following bilateral cosmetic eye whitening.

RESULTS

Seventeen eyes of 9 patients underwent cosmetic eye-whitening performed between 2 and 48 months prior to referral to one of the centers. Sixteen of the 17 eyes had persistent conjunctival epithelial defects, with 10 eyes requiring amniotic membrane grafting to facilitate re-epithelialization. Four eyes of 2 patients developed limbal stem cell compromise confirmed with in vivo confocal laser scanning microscopy. One patient developed infectious scleritis and diplopia resulting from Tenon capsule scarring. Another patient developed scleral necrosis, secondary infectious scleritis, and infectious endophthalmitis. This patient subsequently developed noninfectious scleritis that required 3-drug-regimen immunosuppression.

CONCLUSION

Severe adverse effects can occur after extensive cosmetic conjunctival resection followed by topical mitomycin C application. Patients and physicians should be aware of the potential sight-threatening complications associated with this eye-whitening procedure.

Combined anterior chamber washout, amniotic membrane transplantation, and topical use of corticosteroids for severe peripheral ulcerative keratitis

PURPOSE

The aim of this study was to evaluate the efficacy of anterior chamber washout, amniotic membrane transplantation, and topical use of corticosteroids in the treatment of severe peripheral ulcerative keratitis with membranous endothelial exudation.

METHODS

Twelve patients (12 eyes) with severe corneal ulceration were included. All ulcers were located at the corneal periphery, accompanied by central corneal epithelial defects and stromal edema. Membranous endothelial exudates were observed by anterior segment optical coherence tomography. The duration of the ulcers was 1 to 10 months (mean, 3.0 ± 2.9 months) before the patients visited our institution. Corneal inflammation and ulceration could not be controlled after 2 weeks of topical antiinflammation treatment. Bacterial, fungal, and Acanthamoeba infections were not detected. Surgical treatment was performed. After the necrotic corneal tissue was cut, exudation clinging to the endothelium was removed. Then, amniotic membrane was placed on the corneal lesion. Postoperatively, corticosteroid eye drops and topical and systemic antiinflammation medication were given. Healing of corneal ulcers and improvement of stromal edema were detected by slit-lamp microscopy. All patients were followed up for 3 to 15 months (mean, 6.5 ± 3.7 months).

RESULTS

All corneal ulcers healed by 1 to 2 weeks after surgery. The corneal stromal edema subsided within 1 month. All patients achieved a stable ocular surface. There was no recurrence during the follow-up.

CONCLUSIONS

Anterior chamber washout and amniotic membrane transplantation combined with topical corticosteroids seems to be effective for the treatment of severe peripheral ulcerative keratitis with endothelial exudates.

Amniotic membrane covering promotes healing of cornea epithelium and improves visual acuity after debridement for fungal keratitis

AIM

To investigate the effect of amniotic membrane covering (AMC) on the healing of cornea epithelium and visual acuity for fungal keratitis after debridement.

METHODS

Twenty fungal keratitis patients were divided into two groups randomly, the AMC group and the control group, ten patients each group. Both debridement of the infected cornea tissue and standard anti-fungus drugs treatments were given to every patients, monolayer amniotic membrane were sutured to the surface of the entire cornea and bulbar conjunctiva with 10-0 nylon suture for patients in the AMC group. The diameter of the ulcer was determined with slit lamp microscope and the depth of the infiltration was determined with anterior segment optical coherence tomography. Uncorrected visual acuity (UCVA) was tested before surgery and three month after healing of the epithelial layer. The healing time of the cornea epithelium, visual acuity (VA) was compared between the two groups using t-test.

RESULTS

There was no statistical difference of the diameter of the ulcer, depth of the infiltration, height of the hypopyon and VA between the two groups before surgery (P>0.05). The average healing time of the AMC group was 6.89±2.98d, which was statistically shorter than that of the control group (10.23±2.78d) (P<0.05). The average UCVA of the AMC group was 0.138±0.083, which was statistically better than that of the control group (0.053±0.068) (P<0.05).

CONCLUSION

AMC surgery could promote healing of cornea epithelium after debridement for fungal keratitis and lead to better VA outcome.

In vitro characterization of patches of human mesenchymal stromal cells

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

Amniotic membrane covering for facial nerve repair

Amniotic membranes have been widely used in ophthalmology and skin injury repair because of their anti-inflammatory properties. In this study, we measured therapeutic efficacy and determined if amniotic membranes could be used for facial nerve repair. The facial nerves of eight rats were dissected and end-to-end anastomosis was performed. Amniotic membranes were covered on the anastomosis sites in four rats. Electromyography results showed that, at the end of the 3(rd) and 8(th) weeks after amniotic membrane covering, the latency values of the facial nerves covered by amniotic membranes were significantly shortened and the amplitude values were significantly increased. Compared with simple facial nerve anastomosis, after histopathological examination, facial nerve anastomosed with amniotic membrane showed better continuity, milder inflammatory reactions, and more satisfactory nerve conduction. These findings suggest that amniotic membrane covering has great potential in facial nerve repair.

Amniotic membrane modulates innate immune response inhibiting PRRs expression and NF-κB nuclear translocation on limbal myofibroblasts

Corneal damage observed in a viral infection such as herpetic stromal keratitis is mainly caused by proinflammatory molecules released by resident cells in the response to viral antigens. There are pattern recognition receptors like MDA5, RIG-1, and TLR3, that recognize viral dsRNA and after activation, the innate immune response is exacerbated inducing the synthesis and secretion of inflammatory cytokines through NF-κB activation. Amniotic membrane (AM) has demonstrated to reduce inflammation by several mechanisms, however the effect of AM on innate immune receptors such as MDA5, RIG-1, and TLR3 has not been reported. In this study, we have determined that the presence of AM significantly inhibited the synthesis and secretion of proinflammatory cytokines on human limbal myofibroblasts (HLM) stimulated with poly I:C. Similarly, the presence of AM reduced the protein expression of MDA5, RIG-1, and TLR3 on poly I:C stimulated HLM. Additionally, the presence of the AM significantly inhibited the NF-κB nuclear translocation when the HLM were poly I:C stimulated, and concomitantly, the AM was able to relocate cadherins affecting the myofibroblastic cellular morphology. These results suggest that AM generates an anti-inflammatory microenvironment, and specific inhibition of NFκB nuclear translocation on infected corneal tissue would reduce the inflammation undesirable effects, explaining in part the beneficial usefulness of transplanting AM on herpetic stromal keratitis.

Amniotic membrane graft to conjunctival flap in treatment of non-viral resistant infectious keratitis: a randomised clinical study

PURPOSE

To evaluate and compare the results of bipedicle conjunctival flap (CF) and cryopreserved amniotic membrane graft (AMG) in the treatment of non-viral infectious keratitis resistant to medical treatment.

METHODS

This prospective randomised interventional study included 40 eyes of 40 patients with resistant non-viral infectious keratitis. Twenty eyes received CF and 20 eyes received AMG. In the CF group, there were 12 eyes with fungal keratitis, 7 eyes with bacterial keratitis and 1 eye with Acanthamoeba keratitis. In the AMG group there were 13 eyes with fungal keratitis, 5 eyes with bacterial keratitis and 2 eyes with Acanthamoeba keratitis. In the CF group, three ulcers had descemetocele and four ulcers were perforated. In the AMG group, four ulcers had descemetocele and two ulcers were perforated. In CF, 360° peritomy was done and a bipedicle CF from the upper conjunctiva was dissected from Tenon's capsule, mobilised to cover the cornea and sutured to episclera. In AMG, one or two layers of AM were trimmed to fit the ulcer and sutured to the cornea. The follow-up period was 6 months.

RESULTS

Successful results were observed in 18/20 eyes (90%) in each group. Postoperatively, no significant differences between the two groups were found regarding success rate (p=1.0), epithelialisation time (p=0.75) or visual acuity improvement (p=0.84).

CONCLUSIONS

CF and AMG are effective in treatment-resistant infectious keratitis. They could restore ocular surface integrity and provide metabolic and mechanical support for corneal healing. For large corneal perforation, it may be better to use another procedure such as penetrating keratoplasty to restore ocular integrity.

Evaluation of human amniotic membrane as a wound dressing for split-thickness skin-graft donor sites

Human amniotic membrane (HAM) has been used as a biomaterial in various surgical procedures and exceeds some qualities of common materials. We evaluated HAM as wound dressing for split-thickness skin-graft (STSG) donor sites in a swine model (Part A) and a clinical trial (Part B). Part A: STSG donor sites in 4 piglets were treated with HAM or a clinically used conventional polyurethane (PU) foil (n = 8 each). Biopsies were taken on days 5, 7, 10, 20, 40, and 60 and investigated immunohistochemically for alpha-smooth muscle actin (αSMA: wound contraction marker), von Willebrand factor (vWF: angiogenesis), Ki-67 (cell proliferation), and laminin (basement membrane integrity). Part B: STSG donor sites in 45 adult patients (16 female/29 male) were treated with HAM covered by PU foam, solely by PU foam, or PU foil/paraffin gauze (n = 15 each). Part A revealed no difference in the rate of wound closure between groups. HAM showed improved esthetic results and inhibitory effects on cicatrization. Angioneogenesis was reduced, and basement membrane formation was accelerated in HAM group. Part B: no difference in re-epithelialization/infection rate was found. HAM caused less ichor exudation and less pruritus. HAM has no relevant advantage over conventional dressings but might be a cost-effective alternative.

Cultivation and phenotypic characterization of rabbit epithelial cells expanded ex vivo from fresh and cryopreserved limbal and oral mucosal explants

PURPOSE

To compare the morphology of cultured rabbit epithelial sheets and the expression of stem cells with differentiated cell markers of cultivated epithelial cells from fresh and cryopreserved limbal and oral mucosal biopsies.

MATERIALS AND METHODS

Six New Zealand white rabbits were divided into two groups of three, from which limbal and oral mucosal biopsies were taken. Harvested tissues from each rabbit were brought to immediate cultivation, while another set of tissues was cryopreserved. Cultivation was performed by the explant culture technique using human amniotic membrane as a culture substrate, co-culturing with 3T3 fibroblasts and using the air-lifting method. Cells were cultured for three weeks; then cultured epithelial sheets were stained with hematoxylin-eosin and examined for expression patterns of p63, keratin 3 (K3) and connexin 43 (Cx43). Cryopreservation was carried out using the vitrification method. Tissues were preserved in liquid nitrogen using 25% dimethyl sulfoxide combined with 25% propylene glycol in Dulbecco's Modified Eagle's Medium containing 20% fetal bovine serum. After two months, the tissues were warmed, cultured and stained using the same processes as for fresh tissue cultures.

RESULTS

Cultivation of fresh limbal and fresh oral mucosal tissues showed epithelial stratification, with two to five cell layers. Immunohistochemical staining showed p63-positive cells in basal and intermediate cell layers. K3 staining was observed in cells in the suprabasal layer, while expression of Cx43 was scattered throughout all layers of the epithelia. All culture sheets expressed p63, K3 and Cx43 with the exception of one sheet from the oral mucosal culture that was p63-negative. Cultured epithelial sheets from cryopreserved tissues showed results similar to those from fresh tissue culture.

CONCLUSIONS

This study found that cells in cultivated fresh limbal and oral mucosal tissues had similar morphology to cells in cultivated cryopreserved limbal and oral mucosal tissues, both containing a heterogeneous population of cells including stem cells and differentiated cells.

Validation of an alternative microbiological method for tissue products

According to the European Pharmacopoeia sterility testing of products includes an incubation time of 14 days in thioglycollate medium and soya-bean casein medium. In this case a large period of time is needed for product testing. So we designed a study to evaluate an alternative method for sterility testing. The aim of this study was to reduce the incubation time for the routinely produced products in our tissue bank (cornea and amnion grafts) by obtaining the same detection limit, accurateness and recovery rates as the reference method described in the European Pharmacopoeia. The study included two steps of validation. Primary validation compared the reference method with the alternative method. Therefore eight bacterial and two fungi test strains were tested at their preferred milieu. A geometric dilution series from 10 to 0.625 colony forming unit per 10 ml culture media was used. Subsequent to the evaluation the second part of the study started including the validation of the fertility of the culture media and the parallel testing of the two methods by investigating products. For this purpose two product batches were tested in three independent runs. Concerning the validation we could not find any aberration between the alternative and the reference method. In addition, the recovery rate of each microorganism was between 83.33 and 100 %. The alternative method showed non-inferiority regarding accuracy to the reference method. Due to this study we reduced the sterility testing for cornea and amniotic grafts to 9 days.

Subconjunctival amniotic membrane free graft in rabbit eyes: effects on fibrovascular reaction

PURPOSE

The purpose of our study is to investigate the effect of subconjunctival amniotic membrane free graft on subconjunctival fibrovascular reaction.

METHODS

Twelve healthy male white New Zealand rabbits were used for the study. The rabbits were divided randomly into two groups: Study Group (n=6) and Control Group (n=6). In the Study Group, a 4mm limbal incision was made and a 4×4mm subconjunctival pocket was created with blunt dissection. A 4×4mm single layer of free amniotic membrane was placed in the pocket in an epithelium-up fashion without suturing. The limbal opening was secured with 10-0 nylon sutures on both sides. In the Control Group, a 4mm limbal incision was made, a 4×4mm subconjunctival pocket was created with blunt dissection, and the limbal opening was closed with 10-0 nylon sutures on both sides. After the first month, sclero-conjunctival blocks were obtained from the operated area and sections were stained with hematoxylin and eosin, Masson trichrome, and Ki67, SMA and CD34 antibodies.

RESULTS

The number of fibroblasts, lymphocytes and macrophages was significantly higher in the Study Group than in the Control Group. The number of Ki67- and SMA-positive cells, and CD34-positive vessels was also significantly higher in the Study Group. Amniotic membrane appeared to form folds in all the specimens.

CONCLUSION

The higher fibrovascular reaction shown by our histopathological examination indicates that free human amniotic membrane grafting without suturing is not useful in decreasing the subconjunctival fibrovascular reaction at the first postoperative month in rabbit eyes.

Preparation, indications and results of human amniotic membrane transplantation for ocular surface disorders

In comparison with other biologic tissues used as reconstructive grafts, the amniotic membrane has the advantage that it is thinner and better tolerated by the patient. Amniotic membrane, when appropriately preserved, can be used as a substrate replacement, such that host cells can migrate into the membrane to form new and healthy tissue. The amniotic membrane is the deeper layer of the fetal membrane; it is avascular, multilayered tissue with antiangiogenic, antiscarring and anti-inflammatory properties. Since it does not express antigens of histocompatibility, the membrane is never rejected by the receiving tissues. In addition, the beneficial effects of reducing inflammation and neovascularization persist for a long time, if properly cryopreserved.

Amniotic membrane properties and current practice of amniotic membrane use in ophthalmology in Slovenia

Amniotic membrane (AM) is the innermost, multilayered part of the placenta. When harvested, processed and stored properly, its properties, stemming from AM biological composition, make it a useful tissue for ophthalmic surgery. AM was shown to have several beneficial effects: it promotes epithelization, has antimicrobial effects, decreases inflammation, fibrosis and neovascularization. Many case reports and case series as well as practical experience (e.g. reconstruction of conjunctival and corneal defects, treatment of corneal ulcers) demonstrated the beneficial effect of AM for different ophthalmological indications. The combination of the above mentioned beneficial effects and reasonable mechanical properties are also the reason why AM is used as a substrate for ex vivo expansion of epithelial progenitor cells. Recently, amnion-derived cells, which also have stem cell characteristics, have been proposed as potential contributors to cell-based treatment of ocular surface disease. However, the use of AM remains one of the least standardized methods in ophthalmic surgery. In this review, the various properties of AM and its current clinical use in ophthalmology in Slovenia are discussed.

Clinical transplantation of ex vivo expanded autologous limbal epithelial cells using a culture medium with human serum as single supplement: a retrospective case series

PURPOSE

Presently, our clinic is the only centre in Scandinavia that offers patients with corneal surface pathology including limbal stem cell deficiency (LSCD) transplantation of ex vivo expanded limbal epithelial cells (LECs). We here present clinical data of the first nine patients with LSCD who were transplanted with autologous LECs expanded in medium completely free of any animal-derived products and non-human/recombinant growth factors (including Cholera Toxin), and with autologous human serum as the only growth supplement.

METHODS

We conducted a noncomparative retrospective study of patients with LSCD at our centre between 2009 and 2011. The diagnosis was based on history and clinical signs. A biopsy was taken from healthy limbus, and the epithelium was expanded on amniotic membrane (AM) in medium containing autologous serum and subsequently transplanted to the affected eye.

RESULTS

Successful outcome was defined as relief of pain and photophobia and/or improved best corrected visual acuity (BCVA) and/or reestablishment of a stable corneal epithelium and regression of corneal vascularization. Five of the nine transplanted patients (55.6%) had an improvement in either subjective symptoms or objective findings (11- to 28-month follow-up).

CONCLUSIONS

Our clinical study shows that patients with LSCD can be treated successfully with transplantation of LECs expanded ex vivo in a medium with autologous serum as the only growth supplement. The use of this novel culture system, which is devoid of animal-derived products and non-human/recombinant growth factors (including Cholera Toxin), reduces the risks of inter-species disease transmission and host immune responses to xenogenic proteins, both obvious advantages for the patient.

Repair of oronasal fistulae by interposition of multilayered amniotic membrane allograft

BACKGROUND

Oronasal fistulas are a frequent complication after cleft palate surgery. Numerous repair methods have been described, but wound-healing problems occur often. The authors investigated, for the first time, the suitability of multilayered amniotic membrane allograft for fistula repair in a laboratory experiment (part A), a swine model (part B), and an initial patient series (part C).

METHODS

In part A, one-, two-, and four-layer porcine and human amniotic membranes (n = 20 each) were fixed in a digital towing device and the force needed for rupture was determined. In part B, iatrogenic oronasal fistulas in 18 piglets were repaired with amniotic membrane allograft, autofetal amniotic membrane, or small intestinal submucosa (n = 6 each). Healing was evaluated by probing and visual inflammation control (no/moderate/strong) on postoperative days 3, 7, 10, and 76. Histological analysis was performed to visualize tissue architecture. In part C, four patients (two women and two men, ages 21 to 51 years) were treated with multilayered amniotic membrane allograft.

RESULTS

In part A, forces needed for amniotic membrane rupture increased with additional layers (p < 0.001). Human amniotic membrane was stronger than porcine membrane (p < 0.001). In part B, fistula closure succeeded in all animals treated with amniotic membrane with less inflammation than in the small intestinal submucosa group. One fistula remained persistent in the small intestinal submucosa group. In part C, all fistulas healed completely without inflammation.

CONCLUSIONS

Amniotic membrane is an easily available biomaterial and can be used successfully for oronasal fistula repair. The multilayer technique and protective plates should be utilized to prevent membrane ruptures.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, V.

Role of multilayered amniotic membrane transplantation for the treatment of resistant corneal ulcers in North India

To study the role of multilayer amniotic membrane transplantation (AMT) in the treatment of non-healing corneal ulcers. This study included 28 patients with non-healing bacterial corneal ulcers. AMT was performed using the 'overlay on-inlay' technique'. The outcome was assessed in terms of best corrected visual acuity (BCVA), corneal re-epithelization, graft/tissue edema and vascularity, graft melting, graft retraction, infection of graft and surface necrosis. The success rate of ulcer healing was 82.1 % (23 patients) 1 month after surgery, 78.5 % (22 patients) after 3 months and 75 % (21 patients) after 6 months. In the early post-operative period, BCVA deteriorated in all patients (perception of light to hand movement) but improved later. In 26 of the 28 patients (92.8 %) graft retraction occurred after 1 month and neovascularization was seen in 17 of the 28 patients (60.7 %). Multilayer AMT using an overlay on-inlay graft in non-healing bacterial corneal ulcers is a good option in terms of ulcer healing and symptomatic improvement.

Corneal Debridement Update: Adjuvant Therapies and Wound Healing

Corneal debridement techniques have seen evolution in instrumentation and indication. Although the techniques themselves are simple and usually effective, there is often the need for adjuvant topical therapies to augment healing and/or prevent recurrence of disease. To better understand the requirement for adjuvant therapies, the current theories of corneal wound healing are reviewed.

Management, clinical outcomes, and complications of shield ulcers in vernal keratoconjunctivitis

PURPOSE

To assess the clinical outcomes and complications of shield ulcers by various treatment methods.

DESIGN

Retrospective, interventional case series.

METHODS

setting: Cornea and anterior segment service of L.V. Prasad Eye Institute, India. study population: One hundred ninety-three eyes of 163 patients clinically diagnosed with vernal keratoconjunctivitis and shield ulcers. intervention: The treatment algorithm was based on the Cameron clinical grading of shield ulcers. Grade 1 ulcers received medical therapy alone. Grade 2 and grade 3 ulcers received either medical therapy alone or medical therapy combined with debridement, amniotic membrane transplantation (AMT), or both. main outcome measures: Re-epithelialization time and best-corrected visual acuity.

RESULTS

Grade 1 ulcers were seen in 71 (37%) eyes, grade 2 ulcers were seen in 79 (41%) eyes, and grade 3 ulcers were seen in 43 (22%) eyes. In the grade 1 group, re-epithelialization was seen in 67 (94%) eyes. In the grade 2 group, re-epithelialization was seen in 36 (88%) eyes that received medical treatment, in 20 (95%) eyes that underwent debridement, and in 17 (100%) eyes that underwent AMT. In the grade 3 group, re-epithelialization was seen in only 1 (1.7%) eye that received medical treatment, whereas it was seen in all eyes that underwent debridement and AMT. The mean best-corrected visual acuity after re-epithelialization of the shield ulcer was 20/30, 20/30, and 20/40 in the grade 1, grade 2, and grade 3 groups, respectively. Recurrence and secondary bacterial keratitis were seen in 28 (14.5%) and 20 (10%) eyes, respectively.

CONCLUSIONS

Grade 1 shield ulcers respond well to medical therapy alone, whereas grade 2 ulcers occasionally may require additional debridement or AMT. Grade 3 ulcers, however, largely are refractory to medical therapy and require debridement and AMT for rapid re-epithelialization.

Clinical Transplantation of Individualized Recipient Serum-Adapted Cornea Reduces the Risk of Graft Rejection after Keratoplasty

Corneal diseases cause severe visual impairment that necessitates corneal transplantation and frequently repetitive procedures due to graft rejection. We tested the hypothesis that exposure of donor corneas to recipient serum-derived factors during eye banking triggers a preoperative adaptation that is beneficial for postoperative tolerance. Donor corneas were incubated in a medium containing human serum (HS) obtained in each case from the prospective graft recipient in order to individually expose the donor cornea to the recipient's serum. All recipient serum-adapted corneas (RSACs) fulfilled the clinical criteria required by the national law and were transplanted successfully. The postoperative ophthalmological examination extended up to 8 years. All RSACs were tolerated by their recipients and did not cause postoperative complications and no rejection. Proteomic analysis of corneas cultivated in culture medium containing either fetal calf serum (FCS) that is routinely used for cornea banking or HS revealed different patterns of proteins. HS-cultured corneas showed a greater proteomic similarity with native human corneas than did the FCS-cultured corneas, indicating a differential nutrification of the cultured corneal tissue by HS-derived factors. The clinical results show for the first time that postoperative complications such as tissue intolerance and graft rejection might be managed if the corneal tissue is individually adapted to the recipient's serum trophic factors. This new donor tissue treatment procedure offers incontrovertible advantages and could be adapted for low-risk eyes as well as other transplantable tissues.

The culture of limbal epithelial cells

The transplantation of cultured limbal epithelial cells (LEC) has since its first application in 1997 emerged as a promising technique for treating limbal stem cell deficiency. The culture methods hitherto used vary with respect to preparation of the harvested tissue, choice of culture medium, culture time, culture substrates, and supplementary techniques. In this chapter, we describe a procedure for establishing human LEC cultures using a feeder-free explant culture technique with human amniotic membrane (AM) as the culture substrate.

In vitro characterization and ex vivo surgical evaluation of human hair keratin films in ocular surface reconstruction after sterilization processing

The disadvantages of human amniotic membrane (hAM), used for ocular surface reconstruction, necessitate the development of standardized alternatives. Keratin-derived-films (KF) have been indicated as transferable substrate for cell cultivation and tissue engineering. The impact of different sterilization procedures on KF and surgical feasibility were investigated. Human hair KF were prepared and sterilized; optical, biomechanical properties, in vitro cell seeding efficiency and proliferation of human corneal epithelial cells were studied and compared with hAM. Surgical feasibility was tested on enucleated porcine eye. Sterilized KF showed higher light transmission and significantly higher E-modulus than hAM; cell-seeding-efficiency and proliferation rate were not affected. Although KF could be surgically handled, suture placement was more difficult compared to hAM. Plasma treatment seems the best sterilization method for KF; it does not affect cell biology or optical and biomechanical properties. However material modifications are requested before KF may represent a feasible alternative for ocular surface reconstruction.

Amniotic membrane in oral and maxillofacial surgery

PURPOSE

Following its renaissance in ophthalmology during the 1990s, preserved human amniotic membrane (HAM) has become an attractive biomaterial for all surgical disciplines. This article reviews the current and potential use of HAM in oral and maxillofacial surgery, its postulated properties and common preservation techniques.

METHODS

Literature was identified by an electronic search of PubMed in July 2012; this was supplemented from the reference lists of the consulted papers.

RESULTS

HAM has been used in the field of oral and maxillofacial surgery from 1969 onwards because of its immunological preference and its pain-reducing, antimicrobial, mechanical and side-dependent adhesive or anti-adhesive properties. The effects of HAM on dermal and mucosal re-epithelialisation have been highlighted. Typically, HAM is applied after being banked in a glycerol-preserved, DMSO-preserved or freeze-dried and irradiated state. Whereas the use of HAM in flap surgery and in intra-oral and extra-oral lining is reported frequently, novel HAM applications in post-traumatic orbital surgery and temporomandibular joint surgery have been added since 2010. Tissue engineering with HAM is a fast-expanding field with a high variety of future options.

CONCLUSIONS

Preserved HAM is considered to be a safe and sufficient biomaterial in all fields of oral and maxillofacial wound healing. Recently published novel indications for HAM application lack a high level of evidence and need to be studied further.

Amniotic membrane in the management of strabismus reoperations

PURPOSE

To reduce postoperative scar formation and to improve duction using amniotic membrane (AM) in strabismus reoperations.

METHODS

A prospective study of interventional case series comprised of 14 patients with restrictive strabismus. Objective clinical findings (visual acuity, angle of deviations and degree of duction deficits) were recorded in both the pre- and post-operative periods. Strabismus surgery included the excision of adhesions and scar tissue, repositioning of extraocular muscles (according to the degree of deviations) and placement of two sheets, one between muscle and tenon and the other between muscle and sclera. Conjunctival recession with covering of the bare sclera using AM was also performed.

RESULTS

The mean preoperative deviation of the patients was 34.3 prism diopters (PD) and mean post-operative deviation was 4.6 PD. The mean pre-operative duction deficit of the patients was 1.7; mean post-operative duction deficit was 0.2. Postoperatively all patients improved in relation to deviation and duction. Less than 8 PD deviations with no duction deficits were achieved in 12 (86 %) of the patients.

CONCLUSIONS

Amniotic membrane placement around the extraocular muscle improves the duction and decreases the residual angle of deviations by inhibiting postoperative scar formation.

Amniotic membrane transplantation for acute ocular burns

BACKGROUND

Ocular surface burns can be caused by chemicals (alkalis and acids) or by direct heat. Amniotic membrane transplantation (AMT) performed in the acute phase (day 0 to day 7) of an ocular surface burn is reported to relieve pain, accelerate healing and reduce scarring and blood vessel formation. The surgery involves applying a patch of amniotic membrane (AM) over the entire ocular surface up to the eyelid margins.

OBJECTIVES

To assess the effects of AMT on the eyes of people having suffered acute ocular surface burns.

SEARCH METHODS

We searched CENTRAL (which contains the Cochrane Eyes and Vision Group Trials Register) (The Cochrane Library 2012, Issue 6), MEDLINE (January 1946 to June 2012), EMBASE (January 1980 to June 2012), Latin American and Caribbean Literature on Health Sciences (LILACS) (January 1982 to June 2012), the metaRegister of Controlled Trials (mRCT) (www.controlled-trials.com), ClinicalTrials.gov (www.clinicaltrials.gov) and the WHO International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en). We did not use any date or language restrictions in the electronic searches for trials. We last searched the electronic databases on 11 June 2012.

SELECTION CRITERIA

We included randomised trials of medical therapy and AMT applied in the first seven days after an ocular surface burn compared to medical therapy alone.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed the risk of bias of included studies and extracted relevant data. We contacted trial investigators for missing information. We summarised data using risk ratios (RRs) and mean differences (MDs) as appropriate.

MAIN RESULTS

We included one RCT of 100 participants with ocular burns that were randomised to treatment with AMT and medical therapy or medical therapy alone. A subset of patients (n = 68) who were treated within the first seven days of the injury met the inclusion criteria and were included in the analysis. The remaining 32 eyes were excluded. The included subset consisted of 36 moderate (Dua classification II-III) and 32 severe (Dua classification IV-VI) ocular burns from alkali, acid and thermal injuries. In the moderate category, 13/20 control eyes and 14/16 treatment eyes had complete epithelialisation by 21 days. The RR of failure of epithelialisation by day 21 was 0.18 in the treatment group (95% confidence interval (CI) 0.02 to 1.31; P = 0.09). Mean LogMAR final visual acuities were 0.06 (standard deviation (SD) 0.10) in the treatment group and 0.38 (SD 0.52) in the control group, representing a MD of -0.32 (95% CI -0.05 to -0.59). In the severe category, 1/17 treatment and 1/15 control eyes were epithelialised by day 21. The RR of failure of epithelialisation in the treatment group was 1.01 (95% CI 0.84 to 1.21; P = 0.93). Final visual acuity was 1.77 (SD 1.31) in the treated eyes and 1.64 (SD 1.48) in the control group (MD 0.13; 95% CI -0.88 to 1.14). The risks of performance and detection biases were high, because treating personnel and outcome assessors could not be masked to treatment. There was also a high risk of bias in the visual outcomes of the moderate category, since mean visual acuity was significantly worse at presentation in the control eyes. This reduced confidence in the study findings.

AUTHORS' CONCLUSIONS

Conclusive evidence supporting the treatment of acute ocular surface burns with AMT is lacking. Heterogeneity of disease presentation, variations in treatment, undefined criteria for treatment success and failure, and non-uniform outcome measures are some of the factors complicating the search for clear evidence regarding this treatment.

Amniotic membrane: from structure and functions to clinical applications

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

PI3-K/Akt/JNK/NF-κB is essential for MMP-9 expression and outgrowth in human limbal epithelial cells on intact amniotic membrane

Matrix metalloproteinase-9 (MMP-9) plays an important role in the outgrowth of expanded human limbal epithelial cells on intact amniotic membranes (AM). The mechanisms of MMP-9 expression and cell outgrowth remain unknown. Here, we demonstrated that MMP-9 is preferentially expressed at the leading edge of limbal epithelial outgrowth. Treatment with the inhibitors of PI3-K (LY294002), Akt (SH-5), MEK1/2 (U0126), and JNK1/2 (SP600125) attenuated the outgrowth area, indicating that PI3-K/Akt, p42/p44 MAPK, and JNK1/2 are involved in the outgrowth of intact AM-expanded limbal epithelial cells. However, MMP-9 expression at both transcriptional and translational levels was attenuated by treatment with SP600125, LY294002, or SH-5, not by U0126 and SB202190, suggesting that JNK1/2 and PI3-K/Akt participate in MMP-9 expression. Moreover, NF-κB phosphorylation and nuclear translocation was especially noted at the leading edge, which was attenuated by treatment with SP600125 or LY294002. Helenalin, a selective NF-κB inhibitor, reduced both the limbal epithelial outgrowth and MMP-9 expression. Finally, the data reveal that PI3-K/Akt is an upstream component of the JNK1/2 pathway in MMP-9 expression. Thus, both MAPKs and PI3-K/Akt are required for limbal epithelial outgrowth on intact AM, only the PI3-K/Akt/JNK is essential for MMP-9 expression mediated through activation of transcriptional factor NF-κB in this model.

Ex vivo expanded autologous limbal epithelial cells on amniotic membrane using a culture medium with human serum as single supplement

In patients with limbal stem cell deficiency (LSCD), transplantation of ex vivo expanded human limbal epithelial cells (HLECs) can restore the structural and functional integrity of the corneal surface. However, the protocol for cultivation and transplantation of HLECs differ significantly, and in most protocols growth additives such as cholera toxins, exogenous growth factors, hormones and fetal calf serum are used. In the present article, we compare for the first time human limbal epithelial cells (HLECs) cultivated on human amniotic membrane (HAM) in a complex medium (COM) including fetal bovine serum to a medium with human serum as single growth supplement (HSM), and report on our first examinations of HLECs expanded in autologous HSM and used for transplant procedures in patients with LSCD. Expanded HLECs were examined by genome-wide microarray, RT-PCR, Western blotting, and for cell viability, morphology, expression of immunohistochemical markers and colony forming efficiency. Cultivation of HLECs in HSM produced a multilayered epithelium where cells with markers associated with LESCs were detected in the basal layers. There were few transcriptional differences and comparable cell viability between cells cultivated in HSM and COM. The p63 gene associated with LESCs were expressed 3.5 fold more in HSM compared to COM, and Western blotting confirmed a stronger p63α band in HSM cultures. The cornea-specific keratin CK12 was equally found in both culture conditions, while there were significantly more CK3 positive cells in HSM. Cells in epithelial sheets on HAM remaining after transplant surgery of patients with LSCD expressed central epithelial characteristics, and dissociated cells cultured at low density on growth-arrested fibroblasts produced clones containing 21 ± 12% cells positive for p63α (n = 3). In conclusion, a culture medium without growth additives derived from animals or from animal cell cultures and with human serum as single growth supplement may serve as an equivalent replacement for the commonly used complex medium for ex vivo expansion of HLECs on HAM.