Amniotic membrane transplantation for persistent epithelial defects with ulceration

Suppression of corneal neovascularization by culture supernatant of human amniotic cells

PURPOSE

To examine the applicability of culture supernatant of human amniotic cells on basic fibroblast growth factor (bFGF)-induced corneal neovascularization.

METHODS

Human amniotic epithelial and mesenchymal cells (AC) were obtained from human amniotic membranes by digesting with collagenase and maintained in serum-containing medium. The AC preparations predominantly contained cytokeratin-positive cells (91.2 +/- 3.1%, n = 4). The culture supernatant was prepared by cultivating AC in serum-free medium for 24 hours. Neovascularization was obtained by a micropocket assay with Hydron pellets containing bFGF. Migration assay was carried out by a double-chamber method using human umbilical vein endothelial cells (HUVEC). Cell growth assay was done by MTT assay using HUVEC.

RESULTS

Basic fibroblast growth factor-induced corneal neovascularization was significantly reduced by administration of AC culture supernatant. When either control or AC culture supernatant was administered three times per day for 10 days, the area with neovascularization was 13.2 +/- 3.2 mm2 and 4.0 +/- 1.4 mm2 for the control and AC culture supernatant-treated eyes, respectively (n = 7, p = 0.021). AC culture supernatant strongly inhibited bFGF-induced migration and cell growth of HUVEC.

CONCLUSIONS

Amniotic cell culture supernatant contains potent inhibitors of neovascularization. This effect is explained in part by inhibition of migration and cell growth of vascular endothelial cells. AC culture supernatant may be applicable for treatment of corneal diseases with neovascularization.

Single and multilayer amniotic membrane transplantation for persistent corneal epithelial defect with and without stromal thinning and perforation

AIMS

To evaluate the efficacy of amniotic membrane transplantation (AMT) in persistent corneal epithelial defect with or without stromal thinning and corneal perforation.

METHODS

28 patients (28 eyes) with persistent corneal epithelial defect unresponsive to medical treatment were given preserved human amniotic membrane transplants. The patients were divided into three groups: group A, persistent corneal epithelial defect 10 eyes; group B, epithelial defect with stromal thinning 13 eyes; and group C, corneal perforation five eyes. AMT was performed using one layer in group A and multilayers in group B and C. The causes of persistent epithelial defect were neurotrophic keratopathy (24 eyes), limbal deficiency (six eyes), exposure keratopathy (four eyes), and Mooren's ulcer (one eye).

RESULTS

Success was noted in 82.1% (23/28 eyes) in all groups, with 80% (8/10 eyes), 84.6% (11/13 eyes), and 80% (4/5 eyes) in groups A, B, and C respectively, with a mean follow up of 10.9 months (1-30 months). The mean epithelialisation time after AMT was 2.1 weeks. The healing times of groups B and C are also significantly shorter than group A (p=0.017 and 0.018, respectively). Corneal stromal thickness was significantly increased in all cases in groups B and C (p=0.006). Those with corneal perforation in group C were completely healed by multilayer AMT. There was no difference in the epithelialisation time between successful cases treated by a single operation (17 eyes) or repeated operation (six eyes). Vision improved in 18.9% (8/28 eyes) and worsened as a result of cataract formation in 2.3% (1/28 eyes). Failure was noted in 17.9% (5/28 eyes), because of corneal infection (two eyes), neurotrophic keratopathy with and without limbal deficiency (two eyes), and intractable corneal perforation (one eye). No patient developed major immediate postoperative complications or graft rejection.

CONCLUSION

Amniotic membrane can successfully treat refractory corneal epithelial defect by promoting epithelial healing and thus prevent corneal perforation. It can be used as a treatment for corneal perforation by restoring corneal stromal thickness so that emergency penetrating keratoplasty can be avoided.

Autologous fibrin-cultured limbal stem cells permanently restore the corneal surface of patients with total limbal stem cell deficiency

BACKGROUND

Ocular burns cause depletion of limbal stem cells, which leads to corneal opacification and visual loss. Autologous cultured epithelial cells can restore damaged corneas, but this technology is still developing. We sought to establish a culture system that allows preservation of limbal stem cells and preparation of manageable epithelial sheets and to investigate whether such cultures can permanently restore total limbal stem cell deficiency.

METHODS

We selected a homogeneous group of patients whose limbal cell deficiency was evaluated by scoring the gravity of the clinical picture and the keratin expression pattern. Stem cells, obtained from the limbus of the contralateral eye, were cultivated onto a fibrin substrate and their preservation was evaluated by clonal analysis. Fibrin cultures were grafted onto damaged corneas.

RESULTS

Fibrin-cultured limbal stem cells were successful in 14 of 18 patients. Re-epithelialization occurred within the first week. Inflammation and vascularization regressed within the first 3-4 weeks. By the first month, the corneal surface was covered by a transparent, normal-looking epithelium. At 12-27 months follow-up, corneal surfaces were clinically and cytologically stable. Three patients had a penetrating keratoplasty approximately 1 year after restoration of their corneal surface. Their visual acuity improved from light perception or counting fingers to 0.8-1.0.

CONCLUSIONS

Preservation of limbal stem cells in culture gives new perspectives on the treatment of ocular disorders characterized by complete limbal stem cell deficiency. The multicenter nature of this study and the handiness and ease of long-distance transportation of the fibrin-cultured epithelial sheets suggest that this technology can now be widely applied.

Ocular surface reconstruction in LOGIC syndrome by amniotic membrane transplantation

PURPOSE

To determine whether preserved amniotic membrane can be used to reconstruct the ocular surface after excision of the invading granulation material typical of LOGIC syndrome (laryngeal and ocular granulation tissue in children from the Indian subcontinent).

METHODS

Granulation tissue was dissected and excised from both eyes of a 10-year-old boy with LOGIC syndrome. This procedure was followed by coverage of the corneal, scleral, and subtarsal regions of each eye with amniotic membrane, which had been stored for 6 months at -70 degrees C.

RESULTS

Initial 2.5-month follow up demonstrated complete disappearance of granulation tissue. The fornices were patent, there was no recurrence of symblepharon, ocular inflammation was suppressed, and the patient reported markedly increased comfort. Both eyelids remained ptotic because of levator muscle atrophy secondary to many years of inability to open either eye. No residual scarring or evidence of granulation tissue was observed in that period. The 10-month follow up demonstrated limited recurrence, particularly where there was an intraoperative break in the amniotic membrane.

CONCLUSIONS

After 24 operations to treat the ocular complications induced by LOGIC syndrome, amniotic membrane transplantation was the first effective treatment. In the early follow up period (2-3 months), there was complete cessation of the proliferation of granulation tissue and reepithelialization of the corneal surface. Longer follow up (10 months) demonstrated limited recurrence, which will require retreatment.

Amniotic membrane surgery

Human amniotic membrane (AM) is composed of three layers: a single epithelial layer, a thick basement membrane, and an avascular stroma. Amniotic membrane has anti-adhesive properties and is felt to promote epithelialization and decrease inflammation, neovascularization, and fibrosis. Amniotic membrane transplantation (AMT) is currently being used for a continuously widening spectrum of ophthalmic indications. Amniotic membrane transplantation has been shown to be effective in the reconstruction of the corneal surface in the setting of persistent epithelial defects, sterile corneal ulcerations, and partial limbal stem cell (LSC) deficiency states, including those secondary to chemical or thermal burns. Amniotic membrane transplantation also has been used in conjunction with limbal stem cell transplantation (LSCT) both in a concurrent fashion as well as in preparation for LSCT. Amniotic membrane transplantation also has been used in place of conjunctival autografting after pterygium excision and to reconstruct the conjunctival surface after removal of conjunctival lesions. Most recently, ex vivo cultivation and expansion of limbal epithelial cells has been performed utilizing AM as a matrix. However, the superiority of AMT over other treatment modalities in many of these settings needs to be substantiated by controlled clinical trials.

Amniotic membrane, tear film, corneal, and aqueous levels of ofloxacin in rabbit eyes after amniotic membrane transplantation

PURPOSE

We evaluated ocular penetration and drug levels in tears after topical ofloxacin instillation in rabbit eyes with amniotic membrane transplantation (AMT).

METHODS

Forty-eight New Zealand White rabbits were used. In the first set of experiments, 24 rabbits (24 eyes) were divided into four groups according to the epithelial removal or AMT. Topical ofloxacin was instilled four times every 15 minutes. One hour after the last eyedrop, the concentration of ofloxacin in the amniotic membrane, cornea, and aqueous humor was evaluated. In the second set of experiments, 24 rabbits were divided into six groups according to AMT (transplantation of lyophilized or fresh amniotic membrane) or duration of application. Ofloxacin ointment or two drops of ofloxacin were applied to the right eye, and then tear samples were collected after 0.5, 1, 2, 4, and 6 hours for the analysis of ofloxacin concentration.

RESULTS

Mean ofloxacin concentrations in the cornea and aqueous humor were statistically higher in deepithelialized cornea regardless of AMT (p < 0.05). The mean tear levels of ofloxacin in the AMT groups were statistically higher than those in non-AMT groups (p < 0.05). There was no statistical significance in the tear level of ofloxacin between lyophilized amniotic membrane groups and fresh amniotic membrane groups nor between 1-hour amniotic membrane-attached groups and 6-hour amniotic membrane-attached groups.

CONCLUSION

Amniotic membrane transplantation seems to interfere with the ocular penetration of topical ofloxacin in normal rabbit corneas but enhances ofloxacin penetration in corneas with epithelial defects. The ofloxacin level in tears was higher in eyes with AMT up to 1 hour after topical ofloxacin use. Therefore, it seems that amniotic membrane has some potential to act as an effective drug delivery system.

Amniotic membrane grafts, "fresh" or frozen? A clinical and in vitro comparison

BACKGROUND/AIMS

The use of "fresh" (hypothermically stored) and frozen amniotic membrane (AM) was compared in a patient with cicatricial pemphigoid with stem cell failure. The viability of both "fresh" and frozen AM epithelial cells was assessed after storage.

METHODS

AM was stored at either +4 degrees C ("fresh") or at -80 degrees C (frozen). A "fresh" graft was applied to the cornea following superficial keratectomy. Subsequently, a further frozen graft was applied to the same eye. Viability of the stored AM epithelium was assessed by investigating membrane integrity and mitochondrial activity.

RESULTS

In both cases the cornea re-epithelialised and visual acuity improved. Improvement, however, was not sustained.

CONCLUSION

Although both procedures led to an improvement in visual acuity, "fresh" tissue performed no better than frozen in promoting re-epithelialisation. The authors suggest that logistical, safety, and cost considerations outweigh any benefits of using "fresh" as opposed to frozen graft material.

Amniotic membrane transplantation in the management of conjunctival malignant melanoma and primary acquired melanosis with atypia

AIM

To evaluate the efficacy of amniotic membrane transplantation (AMT) for the management of conjunctival malignant melanoma and primary acquired melanosis (PAM) with atypia.

METHODS

Four consecutive patients with histologically proved invasive, primary conjunctival malignant melanoma were treated with wide surgical excision and AMT. Amniotic membrane grafts were harvested and processed under sterile conditions according to a standard protocol. The grafts were sutured to the margins of the surface defect. In one case, AMT was combined with a corneoscleral graft.

RESULTS

A satisfactory result and rapid postoperative recovery with few, transient side effects was noted in three patients with limbal/epibulbar melanomas. In another patient with an extensive lesion, involving the epibulbar, forniceal, and palpebral conjunctiva, AMT following wide excision was complicated by symblepharon formation and restricted ocular motility. Monitoring of local recurrence was facilitated by the transparency of the thin graft in all cases. The postoperative follow up time varied between several months and 3 years. In one case, local recurrence of PAM was observed and treated using topical mitomycin.

CONCLUSIONS

AMT is a useful technique for the reconstruction of both small and large surface defects that result from the surgical excision of conjunctival malignant melanoma and PAM. This method facilitates wide conjunctivectomy, although its role in repairing larger defects involving the fornix or palpebral conjunctiva still needs to be established. The transparency of amniotic membrane allows for monitoring of tumour recurrence, which is-together with superior cosmesis-an advantage over thicker (for example, buccal) mucous membrane grafts.

Amniotic membrane transplantation in the management of shield ulcers of vernal keratoconjunctivitis

PURPOSE

To report our experience with amniotic membrane transplantation in the management of severe shield ulcers.

DESIGN

Retrospective, interventional, noncomparative case series.

PARTICIPANTS

Four patients (seven eyes) with grade 2 (ulcer with opaque base) and grade 3 (plaquelike lesions) shield ulcers not responding to steroid therapy with or without surgical debridement.

INTERVENTION

Amniotic membrane transplantation with stromal side down was performed after meticulous debridement of the ulcer.

MAIN OUTCOME MEASURES

Healing of the ulcer with no epithelial defect.

RESULTS

The ulcers healed with disintegration or retraction of the membrane in all patients within 2 weeks.

CONCLUSIONS

Amniotic membrane transplantation in combination with debridement is an effective surgical modality in the management of severe shield ulcers. Further studies are warranted to confirm the efficacy of amniotic membrane transplantation in the management of shield ulcer and its correct position in the treatment algorithm.

Amniotic membrane transplantation in entropion surgery

PURPOSE

To evaluate the role of amniotic membrane transplantation in the management of cicatricial eyelid entropion.

DESIGN

Prospective, noncomparative interventional case series.

PARTICIPANTS

Eighteen consecutive patients with cicatricial entropion.

METHODS

A gray line lid split procedure with vertical anterior lamella repositioning was performed on 25 eyelids (upper or lower) of 18 patients with moderate to severe cicatricial entropion. Preserved human amniotic membrane (AM) was used to cover the bare tarsus up to the lid margin and secured with running 7-0 Vicryl. Impression cytology of the AM was performed at various stages postoperatively to study the epithelialization process.

MAIN OUTCOME MEASURES

(1) Reepithelialization of bare tarsus, (2) extent of tarsal shrinkage, (3) recurrence of entropion.

RESULTS

All the AM grafts took well. The most common complication was hemorrhage below the graft, which occurred in six cases. Complete success with no lashes touching the globe was achieved in 22 of 25 (88%) lids after a minimum follow-up of 12.0 months. The mean follow-up was 17.8 months. Two cases (qualified success) had recurrent trichiasis treated successfully with electrolysis. One case with severe trachomatous upper lid entropion recurred 14 months after surgery. The AM accelerated the epithelialization of bare tarsus; this was demonstrated by lack of fluorescein staining and reversion to skin color within 2 to 3 weeks. However, AM could not prevent tarsal shrinkage. Impression cytology demonstrated that features of conjunctival epithelium were present for the first postoperative month, but this was gradually replaced by squamous metaplasia, with keratinization appearing as early as 3 weeks postoperatively.

CONCLUSIONS

The use of AM in a lid split procedure for correction of cicatricial entropion helps the bare tarsus epithelialize rapidly and improves the initial cosmetic result of surgery.

Amniotic membrane transplantation after the primary surgical management of band keratopathy

PURPOSE

To determine the safety and efficacy of amniotic membrane transplantation to restore and maintain a stable corneal epithelium and reduce ocular surface pain after surgical removal of band keratopathy arising from ocular causes.

METHODS

Fifteen patients (16 eyes) from two centers with band keratopathy secondary to ocular causes underwent amniotic membrane transplantation as a graft after surgical removal of calcific deposits with or without the use of ethylenediaminetetraacetic acid. In a prospective, consecutive, uncontrolled case series, the rate of corneal epithelialization and resultant surface stability were recorded over a mean follow-up period of 14.6 months.

RESULTS

Pain from ocular surface instability was the presenting complaint in 14 of 15 (93.3%) patients and resolved in all cases after the procedure even for those who experienced a recurrence of the calcific deposit. Fifteen of 16 eyes (93.7%) achieved epithelialization with a mean time to epithelial healing of 15.2 days. The only eye that failed to heal was subsequently diagnosed with total limbal stem cell deficiency. Visual acuity improved in five of nine (44%) sighted eyes and remained unchanged in four of nine (56%). No patient experienced any major surgical or medical complication after the procedure.

CONCLUSION

Amniotic membrane transplantation represents a safe and effective method to restore a stable corneal epithelium in eyes after primary surgical removal of band keratopathy arising from ocular causes.

Amniotic membrane transplantation for partial limbal stem cell deficiency

AIM

To examine the efficacy, safety, and long term outcomes of amniotic membrane transplantation for corneal surface reconstruction in cases of partial limbal stem cell deficiency.

METHODS

17 eyes of 15 patients with partial limbal stem cell deficiency underwent superficial keratectomy of the conjunctivalised corneal surface followed by amniotic membrane transplantation. Cases were followed up for at least a year.

RESULTS

All eyes exhibited a stable, intact corneal epithelial surface after a mean follow up period of 25.8 months with no eyes developing recurrent erosion or persistent epithelial defect. The mean time to re-epithelialisation was 22.8 days. Overall improvement in visual acuity was observed in 92.9% of 14 eyes with visual potential. Of those, five eyes gained six or more lines, two eyes gained between four and five lines, six eyes gained between one and three lines, and one eye lost three lines of Snellen acuity. Pain and photophobia were abolished in 86% of cases and substantially reduced in 14%, with all eyes exhibiting decreased vascularisation and inflammation at final follow up.

CONCLUSIONS

Amniotic membrane transplantation appears to be a safe and effective method of restoring a stable corneal epithelium for cases of partial limbal stem cell deficiency and can be considered as an alternative to limbal autograft or allograft.

Antiinflammatory effects of amniotic membrane transplantation in ocular surface disorders

PURPOSE

To determine whether the sequestration of inflammatory cells plays a role in the antiinflammatory effects of amniotic membrane transplantation to the ocular surface.

METHODS

Amniotic membrane grafts were prepared from placental tissue procured from mothers undergoing planned Cesarean sections. A detailed explanation was given to all donors, and a written consent was obtained before processing. Amniotic membrane tissue was dissected into 3- x 3-cm segments, rinsed in phosphate buffered saline, and stored in dimethyl sulfoxide solutions at -80 degrees C until use. In a clinical series, amniotic membrane patches of the ocular surface were performed in 20 eyes of 20 patients with persistent corneal epithelial defects, or as a prophylactic measure after corneal limbal transplantation. Amniotic membrane patches were harvested after a 1-week observation period and were subjected to histopathologic examinations by hematoxylin and eosin staining. Inflammatory cells trapped within the amniotic membrane were labeled by immunocytochemistry using anti-CD14, CD4, CD8, and CD20 antibodies. TUNEL (TdT-mediated dUTP nick end labeling) staining was done to observe cells undergoing apoptosis. The T cell line Molt 4 was co-cultured with amniotic membrane in vitro to observe adhesion of T cells to amniotic membrane.

RESULTS

Various degrees of inflammatory cell infiltration were observed in all clinical samples of amniotic membrane patches. Most of the inflammatory cells stained positively with anti-CD14 antibodies, indicating that these cells were of monocyte/macrophage lineage. Subsets of T cells included both CD4(+) and CD8(+) cells, whereas CD20(+) cells were sparse. TUNEL assays revealed that trapped inflammatory cells exhibited characteristics of cells undergoing apoptosis. Molt 4 invaded within amniotic membrane in an in vitro assay, which was not inhibited by blocking antibodies to beta1 and beta2 integrins.

CONCLUSION

Amniotic membrane attracts and traps inflammatory cells infiltrating the ocular surface, which may explain some of the antiinflammatory properties of the fetal tissue.

Laminin-5 is a component of preserved amniotic membrane

PURPOSE

To determine if laminin-5 is retained in the matrix of cryopreserved human amniotic membrane tissue prepared for ocular surgeries.

METHODS

Amniotic membrane was solubilized in urea/SDS buffer. Constituent proteins were resolved by SDS-PAGE and laminin-5 content was determined by Western blot analysis using a panel of antibodies directed against the alpha3, beta3 or gamma2 chains of the molecule. Human corneal epithelial cells were seeded on amniotic membrane and cultured in the presence or absence of EGF. The cell-membrane construct was examined for laminin-5 content using Western blot analysis and immunofluorescence microscopy.

RESULTS

In preserved amniotic membrane the laminin-5 alpha3 chain is present in both the unprocessed (190-kDa) and processed (160-kDa) forms. The beta3 chain is found in the 145-kDa form. The gamma2 chain appears to be predominantly in the processed (105-kDa) form. Very little of the unprocessed form of the gamma2 chain (155-kDa) could be detected using immunoblot analysis. A similar distribution of laminin-5 was also present in extracts of corneal epithelial cells cultured on amniotic membrane. Immunofluorescence analysis of cells cultured on the membrane demonstrated polarization of laminin-5 at the cell-membrane interface.

CONCLUSIONS

The presence of both the unprocessed and processed forms of laminin-5 alpha3 and gamma2 chains in preserved human amniotic membrane suggests that when used as a substrate in ocular surgeries, this membrane may be capable of promoting corneal epithelial cell motility and adhesion. Regulation of the motile or adhesive function may lie with factors secreted by the corneal epithelium that populates the membrane following surgery.

Multilayer amniotic membrane transplantation in severe ocular graft versus host disease

PURPOSE

To clarify the usefulness of multilayer amniotic membrane transplantation in an unusual case of calcareous corneal degeneration in a patient with graft-versus-host disease.

METHODS

A 20-year-old Caucasian woman had bilateral calcareous corneal degeneration of one year of evolution, secondary to graft-versus-host disease. Treatment for both eyes with topical steroids and antibiotic ointment was not successful. Right eye had a spontaneous corneal perforation, and a three-layer circle amniotic membrane graft was applied to the whole cornea.

RESULTS

During a follow-up period of 20 months we observed stability of the corneal epithelium and stroma. The amniotic membrane-covered area showed rapid epithelization, reduced inflammation and suppressed fibrosis formation.

CONCLUSIONS

Multilayer amniotic membrane transplantation may be considered an alterantive for reconstructing the ocular surface in a patient with severe dry eyes and calcareous corneal degeneration, even with little perforation.

Suppression of interleukin 1alpha and interleukin 1beta in human limbal epithelial cells cultured on the amniotic membrane stromal matrix

AIMS

Amniotic membrane (AM) transplantation reduces inflammation in a variety of ocular surface disorders. The aim of this study was to determine if AM stroma suppresses the expression of the IL-1 gene family in cultured human corneal limbal epithelial cells.

METHODS

Human corneal limbal epithelial cells were cultured from limbocorneal explants of donor eyes on plastic or on the AM stroma. Transcript expression of IL-1alpha, IL-1beta, IL-1 receptor antagonist (RA), and GAPDH was compared with or without addition of lipopolysaccharide to their serum-free media for 24 hours using RNAse protection assay (RPA). Their protein production in the supernatant was analysed by ELISA.

RESULTS

Expression of IL-1alpha and IL-1beta transcripts and proteins was significantly reduced by cells cultured on the AM stromal matrix compared with plastic cultures whether lipopolysaccharide was added or not. Moreover, expression of IL-1 RA by cells cultured in the lipopolysaccharide-free medium was upregulated by AM stromal matrix. The ratio between IL-1 RA and IL-1alpha protein levels in AM cultures was higher than in plastic cultures.

CONCLUSIONS

AM stromal matrix markedly suppresses lipopolysaccharide induced upregulation of both IL-1alpha and IL-1beta. These data may explain in part the effect of AM transplantation in reducing ocular surface inflammation, underscoring the unique feature of the AM as a substrate for tissue engineering.

In vivo and in vitro demonstration of epithelial cell-induced myofibroblast differentiation of keratocytes and an inhibitory effect by amniotic membrane

PURPOSE

To examine the role of epithelial cells in inducing the differentiation of keratocytes into myofibroblasts and to determine whether this effect may be inhibited by amniotic membrane matrix.

METHODS

In vivo, a 9-mm diameter, partial-thickness corneal flap was created in 12 rabbit eyes (6 rabbits), which were equally subdivided into three groups. The first group was implanted with one layer of a 6-mm diameter human amniotic membrane, from which the epithelium had been removed by dispase. The second group received an implantation of dispase-treated amniotic membrane with cultured rabbit corneal epithelial cells. The third group received the same implantation as the second group except that the cultured corneal epithelial cells were sandwiched between two layers of membrane. All corneas were removed 2 weeks later and were subjected to Masson trichrome staining and immunofluorescence staining with monoclonal antibodies to alpha-smooth muscle (alpha-SM) actin for myofibroblasts and cytokeratins for epithelial cells. In vitro collagen gels impregnated with different types of human ocular surface fibroblasts were seeded with or without rabbit corneal epithelial cells before testing for gel contraction.

RESULTS

Positive staining of alpha-SM actin was noted only in keratocytes adjacent to corneal epithelial cells at the incision site and those grown on the basement membrane side of the amniotic membrane. Negative staining was noted when epithelial cells were removed by dispase or when cultured corneal epithelial cells were sandwiched between two layers of membrane. Gel contraction by fibroblasts was significantly promoted when epithelial cells were seeded on the gel. In the latter situation, positive staining of alpha-SM actin was noted in fibroblasts subjacent to epithelial cells but not in those impregnated in the gel.

CONCLUSION

Epithelial cells are capable of inducing the differentiation of adjacent fibroblasts into myofibroblasts; such an induction requires a close epithelial-mesenchymal contact. Amniotic membrane alone does not induce this effect and can help block such induction by epithelial cells.

Multilayered amniotic membrane transplantation for severe ulceration of the cornea and sclera

PURPOSE

To examine the efficacy of amniotic membrane transplantation in the treatment of deep corneal and scleral ulcers.

PATIENTS

A total of 11 patients were recruited for this study: four patients (four eyes) with corneal perforation, five patients (five eyes) with a deep corneal ulcer and descemetocele, and two patients (two eyes) with a scleral ulcer.

METHODS

Ulcers were treated by amniotic membrane transplantation. Separate amniotic membranes were transplanted as material to fill the stromal layer (amniotic membrane filling), as a basement membrane (amniotic membrane graft), and as a wound cover (amniotic membrane patch). After surgery, all cases were treated with artificial tears, autologous serum drops, antibiotic eyedrops, topical corticosteroids, and sodium hyaluronate eyedrops.

RESULTS

Eight eyes (72.7%) healed with epithelialization in 16.5 +/- 8.0 days (range, 7 to 29 days), with five and three eyes showing corneal epithelialization and conjunctival epithelialization, respectively. A persistent epithelial defect was noted in one eye with corneal ulcer after limbal allograft transplantation for a chemical burn and in two eyes with corneal ulcers as a complication of rheumatoid arthritis.

CONCLUSION

Multilayered amniotic membrane transplantation may be effective for the treatment of deep ulceration of the cornea and sclera. In some eyes with total corneal limbal dysfunction or autoimmune disorders, amniotic membrane transplantation alone is not effective.

Amniotic membrane transplantation after extensive removal of primary and recurrent pterygia

OBJECTIVE

To evaluate the postoperative outcome and the recurrence rate after extensive removal of primary and recurrent pterygia combined with amniotic membrane transplantation.

DESIGN

A noncomparative interventional case series.

PARTICIPANTS

Fifty-four eyes in 54 subjects with either primary (n = 33) or recurrent (n = 21) pterygia operated on by one surgeon (SCGT).

INTERVENTION

All subjects were operated on for pterygia with an extensive excision of the lesion followed by amniotic membrane transplantation and intraoperative injection of a depot corticosteroid.

MAIN OUTCOME MEASURES

Cumulative rates of conjunctival (grade 3) and corneal (grade 4) recurrence and incidence of complications.

RESULTS

The mean follow-up was 12.8 +/- 4.3 months for primary and 14.3 +/- 4.9 months for recurrent pterygia. The true recurrence rate (grade 4) was 3.0%, 9.5%, and 5.6% for primary, recurrent, and all pterygia, respectively. The cumulative proportion of recurrence-free eyes at 12 months was 0.90 +/- 0.06 for primary and 0.69 +/- 0.11 for recurrent pterygia (P = 0.047, log-rank test). Removal of the semilunar fold was associated with longer survival times (P = 0.063) and decreased failure rate (P = 0.046). A similar success rate was achieved in double-head pterygia (1 recurrence in 11 eyes).

CONCLUSIONS

Amniotic membrane transplantation is an effective and safe procedure for pterygium surgery, with a relatively low recurrence rate for both primary and recurrent pterygia. It can be a useful alternative to conjunctival autograft when a large conjunctival defect has to be covered, such as in primary double-head pterygia and in large recurrent pterygia.

Reduction in corneal haze and apoptosis by amniotic membrane matrix in excimer laser photoablation in rabbits

PURPOSE

To determine whether preserved human amniotic membrane can reduce corneal haze and keratocyte apoptosis induced by excimer laser photoablation in rabbit corneas.

METHODS

Excimer photoablation was performed bilaterally in 30 rabbits with a 6.0 mm ablation zone and 120 microm depth using the VISX Star laser with the phototherapeutic keratectomy (PTK) mode. One eye was randomly covered by preserved human amniotic membrane secured with 4 interrupted 10-0 nylon sutures, and the other eye served as the control. The amniotic membranes were removed at 1 week, and corneal haze was graded with slitlamp biomicroscopy by 3 masked corneal specialists biweekly for the ensuing 12 weeks until the rabbits were killed. Another 18 rabbits were divided into 4 subgroups and received PTK alone, PTK with membrane, PTK with sham sutures, or PTK with tarsorrhaphy. All eyes were studied histologically, and 3 eyes in each group were studied by in situ terminal deoxynucleotidyl transferase deoxy-UTP-nick end labeling assay at 1, 3, and 7 days and 12 weeks, respectively.

RESULTS

A consistent grading of differences in corneal haze scoring between the control corneas and the amniotic-membrane-covered corneas was noted among the 3 masked observers. Organized reticular post-PTK corneal haze peaked at 7 weeks in both groups, and the corneal haze score in the amniotic-membrane-covered group was significantly less than in the control group from 7 to 12 weeks (all P < .001). Compared to the control corneas, the amniotic-membrane-covered corneas had less inflammatory response at 1 and 3 days, less keratocyte apoptosis in the ablated anterior corneal stroma at 1, 3, and 7 days (P < .001), and less stromal fibroblast cellularity and epithelial hyperplasia at 12 weeks.

CONCLUSIONS

Amniotic membrane matrix introduced at an early stage of the corneal wound healing process effectively reduced corneal haze induced by excimer laser photoablation in rabbits. Studies linking suppression of apoptosis in the acute wound-healing process with reduction of subsequent corneal scarring may have useful clinical applications.

Bacterial contamination of amniotic membrane

AIM

In the light of interest being shown in amniotic membrane grafts for use in ocular surgery, this study aims to identify the bacterial contaminants commonly found on placental membranes from both caesarean and vaginal deliveries.

METHODS

Samples of placental membrane were taken following both elective caesarean and normal vaginal deliveries. Bacterial contaminants were identified.

RESULTS

All samples were contaminated. A greater number of different species were recovered from the vaginal deliveries, including several which were actually or potentially pathogenic.

CONCLUSION

There is a greater risk of contamination from pathogenic bacteria on placentas from vaginal deliveries. It is recommended that amnion for use in ocular surface procedures should be retrieved only from placentas following elective caesarean deliveries.

Amniotic membrane transplantation for symptomatic conjunctivochalasis refractory to medical treatments

PURPOSE. To determine whether preserved human amniotic membrane can restore the large conjunctival defect created during surgical removal of conjunctivochalasis.

METHODS

Amniotic membrane transplantation was performed at two facilities in 40 consecutive patients (47 eyes) with symptomatic conjunctivochalasis refractory to conventional treatments.

RESULTS

The majority of patients were elderly (73.1 +/- 9.7 years) and women (75%). Over a follow-up period of 6.9 +/- 4.3 months, 46 (97.8%) eyes recovered smooth, quiet, and stable conjunctival surfaces. Epithelial defects healed in 16.5 +/- 7.3 days. Episodic epiphora was resolved in 24 of 30 (83.3%) eyes and improved in five other eyes. Notable relief was also noted for such symptoms as fullness or heaviness (19/19, 100%), sharp pain (6/6, 100%), redness (14/17, 88.2%), tiredness (17/20, 80.9%), itching (11/13, 78.6%), blurry or decreased vision (6/8, 75%), burning (8/13, 61.5%), foreign body sensation (8/13, 61.5%), and crust formation (1/2, 50%). Complications included focal inflammation of the host conjunctiva adjacent to the graft (six eyes), scar formation (five eyes), and suture-induced granuloma (one eye).

CONCLUSION

Amniotic membrane transplantation can be considered as an effective means for conjunctival surface reconstruction during removal of conjunctivochalasis.

Amniotic membrane transplantation for repair of leaking glaucoma filtering blebs

PURPOSE

To compare the safety and efficacy of human preserved amniotic membrane transplant with conjunctival advancement for repair of late-onset glaucoma filtering bleb leaks.

METHOD

A prospective, randomized clinical trial compared amniotic membrane transplant with conjunctival advancement in patients with leaking glaucoma filtering blebs. Intraocular pressure, number of glaucoma medications, and reoperation for glaucoma or persistent or recurrent bleb-leak were compared in the two groups. Patients were followed for a minimum of 1 year.

RESULTS

Mean intraocular pressure was the same at 6 (amniotic membrane transplant, 15.4 +/- 4.4, conjunctival advancement 14.1 +/- 6.4, P = 0.6), 12 (amniotic membrane transplant, 15.0 +/- 6.3, conjunctival advancement, 13.2 +/- 6.6, P = 0.5), and 24 (amniotic membrane transplant, 17.2 +/- 7.1, conjunctival advancement, 15.0 +/- 6.3, P = 0.6) months. The mean number of glaucoma medications in use was the same in the two groups at all time intervals. After an average follow-up of 19 months, there were seven failures in the amniotic membrane transplant group (two with persistent leaks that were unresponsive to further suturing, two with late-onset leaks, and three who required repeat glaucoma surgery) and none in the conjunctival advancement group. The cumulative survival rate for amniotic membrane transplant was 81% at 6 months, 74% at 1 year, and 46% at 2 years. The cumulative survival rate was 100% for conjunctival advancement throughout follow-up.

CONCLUSIONS

Amniotic membrane transplantation does not offer an effective alternative to conjunctival advancement for repair of leaking glaucoma filtering blebs.

Human amniotic membrane in the reconstruction of the ocular surface

We sought to determine the efficacy of amniotic membrane transplantation (AMT) in the reconstruction of ocular surface. AMT was performed on 40 eyes with following indications: I, persistent corneal ulceration (n = 12); II, impending perforation (n = 6); III, persistent epithelial defect on the corneal graft (n = 6); IV, recurrent pterygia (n = 10), and V, risk of conjunctival scarring (n = 6). Amniotic membrane was prepared from a fresh placenta under sterile conditions, washed with BSS containing penicillin, streptomycin, neomycin and amphotericin B and stored at -80 degrees C in 1:1 InoSol:Glycerol solution. Donor serological test for HIV, HBV and HCV were all negative. Associated surgical procedures according to indication were performed. Healing of the corneal ulcer in Group I was obtained in 67% of eyes at 1-3 weeks after surgery, Group II: AMT was followed by 'a chaud' keratoplasty in 33% and by planned keratoplasty in 67% patients, Group III: healing of the defect in 33% of eyes in 2-5 postoperative weeks, Group IV: no recurrence of pterygium ingrowth in 70% in the follow up period of 6-14 months, and V: 84% of patients had good eye motility without any synechia formation. We concluded that AMT have shown to be effective in enhancing healing of the corneal defects, in prevention of symblepharon formation and recurrent pterygium ingrowth. In case of impending perforation, AMT alone was not a method of treatment but is useful as a first step procedure in preparing the eye for the corneal transplantation.

Amniotic membrane graft for primary pterygium: comparison with conjunctival autograft and topical mitomycin C treatment

AIM

To study the efficacy and safety of amniotic membrane graft as an adjunctive therapy after removal of primary pterygium, and to compare the clinical outcome with conjunctival autograft and topical mitomycin C.

METHODS

80 eyes of 71 patients with primary pterygia were treated with excision followed by amniotic membrane graft. The result was compared retrospectively with 56 eyes of 50 patients receiving conjunctival autograft, and 54 eyes of 46 patients receiving topical mitomycin C. Patients were followed for at least 6 months, and the averaged follow up periods for the three groups were 13.8, 22.8, and 18.4 months, respectively.

RESULTS

There were three recurrences (3.8%) in the amniotic membrane graft group, three recurrences (5.4%) in the conjunctival autograft group, and two recurrences (3.7%) in the topical mitomycin C group. There was no significant difference in recurrence rate among the three groups (p = 0.879). No major complications occurred in the amniotic membrane graft group or the conjunctival autograft group. One case of infectious scleritis due to scleral ischaemia occurred in the topical mitomycin C group.

CONCLUSION

This study showed that amniotic membrane graft was as effective as conjunctival autograft and mitomycin C in preventing pterygium recurrence, and can be considered as a preferred grafting procedure for primary pterygium.

Current status of limbal conjunctival autograft

The past decade has witnessed several major advances in the field of ocular surface reconstruction. It is now established that the limbal and corneal epithelia belong to the same clonogenic lineage and that conjunctival transdifferentiation does not occur. These facts have engendered the increasing use of limbal transplantation in several ocular conditions involving limbal compromise. Many reports on this procedure have been published in the past year. They add to the growing body of evidence that limbal transplantation is efficacious in replenishing the stem cell pool, promoting improved vision and enhancing ocular comfort. Recent clinical studies on limbal autograft transplantation also underscore the importance of preoperative impression cytology in donor eyes, highlight the fact that transplantation in inflamed eyes is to be avoided, and indicate that the procedure is likely to provide better outcomes if performed several months after ocular surface burns. The appreciation of the utility of amniotic membrane transplantation in ocular surface reconstruction has provided a surgical tool to use in tandem with limbal transplantation. Questions such as why limbal autografts fail, the long-term results of LAT, and whether limbal inclusion is mandatory during conjunctival transplantation after pterygium excision have not been answered fully. Studies on long-term outcomes with limbal allograft transplantation and those reporting on experience with newer techniques such as epithelial transplantation using tissue culture-cultivated epithelium are likely to provide better perspectives on the best way to reconstruct the ocular surface in stem cell-deficient eyes.

Amniotic membrane transplantation for severe neurotrophic corneal ulcers

AIMS

To evaluate whether amniotic membrane transplantation can be an effective alternative treatment for neurotrophic corneal ulcers.

METHODS

Amniotic membrane transplantation was performed in 16 eyes of 15 patients with neurotrophic corneal ulcers and vision equal to or worse than 20/200. The neurotrophic state was developed following keratoplasty (four eyes), herpes zoster ophthalmicus (four eyes), diabetes mellitus (four eyes), radiation (two eyes), removal of acoustic neuroma with neuroparalysis (one eye), and herpes simplex keratitis (one eye).

RESULTS

During a mean follow up period of 18.8 (SD 13.0) months, one to three layers of amniotic membrane with or without additional membrane as a patch were used for 17 procedures in 16 eyes for persistent neurotrophic corneal ulcers. All but four (76.4%) instances of amniotic membrane transplantation achieved rapid epithelialisation in 16.6 (9.0) days. Of the four eyes showing delayed healing, three eyes healed by tarsorrhaphy, and the remaining one eye with corneal perforation required penetrating keratoplasty and tarsorrhaphy. Two eyes gained vision better than 20/200. The healed corneal surface was accompanied by reduced inflammation.

CONCLUSION

Amniotic membrane transplantation can be considered an effective alternative for treating severe neurotrophic corneal ulcers.

Reconstruction of damaged corneas by transplantation of autologous limbal epithelial cells

BACKGROUND

Stevens-Johnson syndrome, ocular pemphigoid, and thermal or chemical burns can cause scarring and opacification of the cornea and loss of vision. Transplantation of epithelial cells from the limbus of the contralateral cornea can restore useful vision. However, this procedure requires a large limbal graft from the healthy eye and is not possible in patients who have bilateral lesions.

METHODS

We took specimens of limbal epithelial cells from the healthy contralateral eyes of six patients with severe unilateral corneal disease. The epithelial cells were cultured and expanded on amniotic membrane. The amniotic membrane, together with the sheet of limbal epithelial cells, was transplanted to the denuded corneal surface of the damaged eye after superficial keratectomy to remove fibrovascular ingrowth. The mean (+/-SD) follow-up period was 15+/-2 months.

RESULTS

Complete reepithelialization of the corneal surface occurred within two to four days of transplantation in all six eyes receiving transplants. By one month, the ocular surface was covered with corneal epithelium, and the clarity of the cornea was improved. In five of the six eyes receiving transplants (83 percent), the mean visual acuity improved from 20/112 to 20/45. In one patient with a chemical burn who had total opacification of the cornea, the acuity improved from the ability to count fingers at 40 cm to 20/200. No patient had recurrent neovascularization or inflammation in the transplanted area during the follow-up period.

CONCLUSIONS

Transplantation of autologous limbal epithelial cells cultured on amniotic membrane is a simple and effective method of reconstructing the corneal surface and restoring useful vision in patients with unilateral deficiency of limbal epithelial cells.

Amniotic membrane transplantation in acute chemical and thermal injury

PURPOSE

To present a case of chemical injury and a case of thermal injury treated by amniotic membrane transplantation in acute phase.

METHODS

Case reports. An eye with sodium hydroxide injury, opaque cornea, and limbal ischemia of more than 180 degrees and an eye with hot tea injury, opaque cornea, stromal edema, and scarring were treated by amniotic membrane transplantation within the first few weeks of injury.

RESULTS

In the eye with sodium hydroxide injury, 4 months after amniotic membrane transplantation, the ocular surface is stable, superficial corneal scarring with vascularization is present, and visual acuity is 20/25. In the eye with thermal injury, 6 months after amniotic membrane transplantation, the ocular surface is stable, but there is superficial scarring and vascularization, and visual acuity is 20/20.

CONCLUSIONS

Amniotic membrane transplantation can be considered in chemical injury with severe limbal ischemia and in severe thermal injury in acute phase. Long-term studies are warranted to evaluate further the efficacy of amniotic membrane transplantation in these clinical situations.

Treatment of persistent corneal epithelial defect with extended wear of a fluid-ventilated gas-permeable scleral contact lens

PURPOSE

To report treatment of persistent corneal epithelial defects unresponsive to other therapies by extended wear of a fluid-ventilated gas-permeable scleral contact lens.

METHODS

In this retrospective study, 14 eyes of 13 consecutive patients referred for the treatment of persistent corneal epithelial defects that failed to heal with conventional therapies or developed epithelial defects after penetrating keratoplasty for persistent corneal epithelial defects were fitted with an extended-wear gas-permeable scleral lens. These included seven eyes of six patients with Stevens-Johnson syndrome and seven eyes of seven patients who did not have Stevens-Johnson syndrome. Twelve eyes had undergone recent penetrating keratoplasty. All 14 eyes were fitted with a gas-permeable scleral contact lens designed to avoid the intrusion of air bubbles under its optic. An antibiotic and corticosteroid were added to the lens fluid reservoir or instilled before each lens insertion in 12 of 14 eyes. The lenses were worn continuously except for brief periods of removal for purposes of cleaning, replacement of the lens fluid reservoir, and examination and photography of the cornea.

RESULTS

Five of the seven persistent corneal epithelial defects associated with Stevens-Johnson syndrome healed. The persistent corneal epithelial defects of four of these eyes re-epithelialized within 7 days, and a fifth healed in 27 days of gas-permeable scleral lens extended wear. A sixth persistent corneal epithelial defect that failed to heal initially re-epithelialized after a subsequent penetrating keratoplasty and gas-permeable scleral lens extended wear. The seventh eye healed after 3 days of gas-permeable scleral lens extended wear, but the persistent corneal epithelial defect subsequently recurred. Three of seven non-Stevens-Johnson syndrome persistent corneal epithelial defects re-epithelialized within 36 hours, 6 days, and 36 days, respectively. Of the six (six of 14) persistent corneal epithelial defects that failed to heal with a gas-permeable scleral lens extended wear, one subsequently healed after multiple amniotic membrane grafts. Microbial keratitis occurred in four eyes (four of 14) and graft failure in one eye, all of which required repeat penetrating keratoplasty.

CONCLUSION

Extended wear of an appropriately designed gas-permeable scleral contact lens was effective in promoting the healing of persistent corneal epithelial defects in some eyes that failed to heal after other therapeutic measures. Re-epithelialization appears to be aided by a combination of oxygenation, moisture, and protection of the fragile epithelium afforded by the scleral lens. However, microbial keratitis represents a significant risk.

Use of nonpreserved human amniotic membrane for the reconstruction of the ocular surface

PURPOSE

To describe the use of nonpreserved human amniotic membrane (NP-AMT) as an alternative to preserved human amniotic membrane (AMT) for the reconstruction of the ocular surface in several diseases.

METHODS

NP-AMT was used in the treatment of five patients with the following diseases: noninvasive conjunctival squamous cell carcinoma, corneal persistent epithelial defect, severe alkali burn, near total limbal deficiency secondary to multiple surgeries, and ocular cicatricial pemphigoid. In some cases, a limbal autograft or allograft was employed simultaneously, sutured on top of the NP-AMT. All sutures were made with 10-0 Nylon and were removed at two weeks.

RESULTS

Ocular surface was satisfactorily reconstructed, eyes were quiet, and patients were comfortable despite prolonged deepithelialization in some cases. There was a case of a limbal autograft ischemia--in the burned patient--that caused partial corneal conjunctivalization. Initially, the NP-AMT looks thickened but thins around the fifth day and looks similar to AMT.

CONCLUSION

Results using NP-AMT are similar to those of AMT. It is a good alternative and it is easily obtained in places were AMT is not available or is too expensive to procure.

Amniotic membrane transplantation for ocular surface reconstruction in Stevens-Johnson syndrome

PURPOSE

To evaluate amniotic membrane transplantation (AMT) for ocular surface reconstruction in Stevens-Johnson syndrome (SJS).

DESIGN

Prospective interventional case series.

PARTICIPANTS

Ten consecutive patients (10 eyes) with SJS that underwent AMT as the first step in staged ocular surface reconstruction were included.

METHODS

Amniotic membrane was processed under sterile conditions from a fresh placenta obtained from cesarean section in a seronegative pregnant woman and stored at -700 degrees C. Symblepharon release, excision of epibulbar fibrous tissue, and clearing of the fibrovascular membrane over the cornea was performed in all cases. Amniotic membrane covered the entire bulbar surface up to the fornices in five eyes; cornea and the perilimbal area in two eyes; cornea, the inferior bulbar surface, and the lower fornix in two eyes; and cornea and the superior bulbar surface in one eye. Obliterated fornices were deepened by use of fornix-formation sutures in all eyes. Symblepharon ring was placed postoperatively for 3 weeks to 2 months. Mean postoperative follow-up was 13.5 months (SD, +3.8 months; range, 9-30 months).

MAIN OUTCOME MEASURES

Restoration of adequate bulbar surface free of symblepharon and good fornix depth were the main outcome measures.

RESULTS

Complete corneal reepithelization occurred in all eyes between 1 and 6 weeks. Adequate bulbar surface and fornix depth were achieved in nine eyes, all of which were free of symblepharon at the final follow-up visit. Cicatricial entropion resolved in four of five lower eyelids and one of two upper eyelids after AMT. One patient had a central corneal melt that required or necessitated a penetrating keratoplasty.

CONCLUSIONS

AMT restores adequate bulbar surface and fornix depth and prevents recurrence of symblepharon in severe cases of SJS.

Amniotic membrane transplantation for acute chemical or thermal burns

PURPOSE

To determine whether preserved human amniotic membrane (AM) can be used to treat ocular burns in the acute stage.

DESIGN

Prospective, noncomparative, interventional case series.

PARTICIPANTS

Thirteen eyes from 11 patients with acute burns, 10 eyes with chemical burns and 3 with thermal burns of grades II-III (7 eyes) and grade IV (6 eyes), treated at 7 different facilities.

METHODS

Patients received amniotic membrane transplantation (AMT) within 2 weeks after the injury.

MAIN OUTCOME MEASURES

Integrity of ocular surface epithelium and visual acuity during 9 months of follow-up.

RESULTS

Ten patients were male and one patient was female; most were young (38.2 +/- 10.6 years). For a follow-up of 8.8 + 4.7 months, 11 of 13 eyes (84.63%) showed epithelialization within 2 to 5 weeks (23.7 +/- 9.8 days), and final visual acuity improved > or = 6 lines (6 eyes), 4 to 5 lines (2 eyes), and 1 to 3 lines (2 eyes); only one eye experienced a symblepharon. Eyes with burns of grade II to III showed more visual improvement (7.3 +/- 3 lines) than those with burns of grade IV (2.3 +/- 3.0 lines; P < 0.05, unpaired t test). In the group with grade II or III burns, none had limbal stem cell deficiency. All eyes in the group with grade IV burns did experience limbal stem cell deficiency.

CONCLUSIONS

Amniotic membrane transplantation is effective in promoting re-epithelialization and reducing inflammation, thus preventing scarring sequelae in the late stage. In mild to moderate burns, AMT alone rapidly restores both corneal and conjunctival surfaces. In severe burns, however, it restores the conjunctival ocular surface without debilitating symblepharon and reduces limbal stromal inflammation, but does not prevent limbal stem cell deficiency, which requires further limbal stem cell transplantation. These results underscore the importance of immediate intervention in the acute stage of eyes with severely damaged ocular surface. Further prospective randomized studies including a control group are required to determine the effectiveness of AMT in acute chemical and thermal burns of the eye.

Identification of antiangiogenic and antiinflammatory proteins in human amniotic membrane

PURPOSE

To identify the potential antiangiogenic and antiinflammatory proteins expressed in human amniotic membrane tissue.

METHODS

Human amniotic epithelial and mesenchymal cells were isolated from human amniotic membranes by sequential trypsin and collagenase digestion. Total RNAs were harvested from freshly obtained human amniotic epithelial and mesenchymal cells. Antiangiogenic and antiinflammatory proteins were detected by the reverse transcriptase-polymerase chain reaction (RT-PCR) technique and further confirmed by DNA sequencing of PCR-amplified transcripts. The distribution of tissue inhibitors of metalloproteinase (TIMPs) were studied further by immunohistochemistry performed on paraffin-embedded amniotic membrane tissue.

RESULTS

RT-PCR results showed that both human amniotic epithelial and mesenchymal cells express interleukin-1 receptor antagonist, all four TIMPs, collagen XVIII, and interleukin-10. Thrombospondin-1 was expressed in all of the epithelial cell specimens and in one out of five mesenchymal cell specimens. Furthermore, immunohistochemistry studies performed on freshly prepared amniotic membrane confirmed that all members of the TIMP family were present in epithelial and mesenchymal cells as well as in the compact layer of the amniotic stroma. In cryopreserved amniotic membranes, positive staining was seen in residual amniotic cells and stroma.

CONCLUSIONS

Human amniotic membrane epithelial and mesenchymal cells express various antiangiogenic and antiinflammatory proteins. Some of those proteins also were found in amniotic membrane stroma. These findings may explain in part the antiangiogenic and antiinflammatory effects of amniotic membrane transplantation.

Amniotic membrane transplantation or conjunctival limbal autograft for limbal stem cell deficiency induced by 5-fluorouracil in glaucoma surgeries

PURPOSE

To determine if human amniotic membrane transplantation or limbal stem cell transplantation is effective to restore the corneal surface with partial or total limbal stem cell deficiency, respectively, caused by 5-fluorouracil (5-FU) toxicity after glaucoma surgeries.

METHODS

Partial and total limbal stem cell deficiency was confirmed by impression cytology as the cause of reduced vision and corneal surface breakdown in a 69-year-old man and a 67-year-old man, respectively, who both had received a total of 105 mg 5-FU injections. Amniotic membrane transplantation or conjunctival limbal autograft was performed for corneal surface reconstruction, respectively.

RESULTS

For a period of 15 months of follow-up, the visual acuity improved, and their corneal surfaces remained avascular, smooth, and without recurrence of limbal stem cell deficiency.

CONCLUSION

Limbal stem cell deficiency can occur as a late complication for patients receiving 5-FU after glaucoma filtering surgeries. Partial limbal stem cell deficiency can be treated with amniotic membrane transplantation alone, whereas limbal transplantation must be considered as an alternative for total limbal stem cell deficiency to restore the corneal surface integrity and vision.

Amniotic membrane patching promotes healing and inhibits proteinase activity on wound healing following acute corneal alkali burn

Amniotic membrane (AM) contains basement membrane components and various proteinase inhibitors. Furthermore, when used as a graft, the basement membrane of AM could block inflammatory insults to a damaged corneal surface. Thus, we evaluated whether amniotic membrane patching could promote the healing process by inhibiting proteolytic damage. Alkali wounds were inflicted on the central corneas of rabbits by applying a round filter paper, 6.0 mm in diameter, soaked in 1 N NaOH for 30 sec. Amniotic membrane patching was performed over the perilimbal sclera immediately after wounding. A total of 115 rabbits were divided into four groups: (1) immediately covered by AM with the amnion cell side down up to the perilimbal sclera (n =26); (2) covered by AM with the stromal side down up to the perilimbal sclera (n =19); (3) anchored to the fornix (n =29); and (4) uncovered as a control (n =41). AM was removed 3 days postoperatively. During follow-ups, epithelial defects, corneal thickness and its opacity of each eye were measured. Some corneas were removed for histopathologic studies and for proteinase activity assay and zymography. The epithelial healing was faster and the corneal thickness was thicker in all three AM-covered groups than in the control (P<0.05). No significant difference was found between covered and anchored groups (P>0.05). Corneal opacity was least in the amnion cell side down group. Infiltration of polymorphonuclear leukocytes (PMNs) was much less in AM-covered groups than in the control. Pathological results were associated with zymographic findings, which revealed much higher proteinase activity in uncovered group than AM-covered groups. Immediate intervention for acute alkali burns with AM as a temporary patch promotes wound healing by inhibiting proteinase activity and PMNs infiltration.

Amniotic membrane as a substrate for cultivating limbal corneal epithelial cells for autologous transplantation in rabbits

PURPOSE

To examine the viability of using human amniotic membrane as substrate for culturing corneal epithelial cells and transplanting them onto severely injured rabbit eyes.

METHODS

An ocular-surface injury was created in the right eye of eight rabbits by a lamellar keratectomy extending 5 mm outside the limbus. Next, from the limbal region of the uninjured left eyes of five of these animals, a small biopsy of corneal epithelial cells was taken and cultured on acellular human amniotic membrane. One month later, the invading conjunctiva that covered the corneal surface of all eight injured eyes was surgically removed. Five of the eyes then received grafts of amniotic membrane containing autologous cultured epithelial cells, whereas the other three received grafts of acellular amniotic membrane alone.

RESULTS

A confluent primary culture of limbal corneal epithelial cells was established on acellular human amniotic membrane after 14 days. Cells were partially stratified and fairly well attached to the underlying amniotic membrane, although a fully formed basement membrane was not evident. The three rabbits that received amniotic membrane transplantation alone all had total epithelial defects on the graft in the early postoperative period. Eyes that were grafted with amniotic membrane that contained cultivated epithelial cells, however, were all successfully epithelialized up to 5 days after surgery.

CONCLUSION

Autologous transplantation of cultivated corneal epithelium is feasible by using acellular amniotic membrane as a carrier.

Differential rapid adhesion of bovine ocular surface epithelial cells to laminin isoforms

PURPOSE

To examine the ability of bovine corneal and conjunctival epithelial cells to adhere to different types of exogenous laminin preparations.

METHODS

The ability of bovine corneal and conjunctival epithelial cells in primary culture to attach to laminin isolated from human placenta or from mouse EHS tumor was measured using a short-term colorimetric adhesion assay. Focal adhesion formation in response to interaction with laminins was determined by immunofluorescence microscopy using antibodies to vinculin and morphometric analysis. The influence of laminin on the secretion of adhesion complex proteins by bovine corneal epithelial cells in culture was analyzed using immunofluorescence microscopy.

RESULTS

In short-term assays, primary bovine corneal epithelial cells demonstrate rapid and efficient adhesion to placental laminin, and significantly more cells contain focal adhesions, compared to those incubated on EHS laminin. In contrast, primary bovine conjunctival epithelial cells adhere equally well to placental and EHS laminin over a range of substrate concentrations. Additionally, the percentage of cells containing focal adhesions is not significantly different. In primary bovine corneal epithelium, the deposition of collagen type IV and collagen type VII into extracellular network-like structures is inhibited in cells cultured on placental laminin compared to cells cultured on EHS laminin.

CONCLUSIONS

In vitro, bovine corneal epithelial cells attach more rapidly and efficiently to exogenous placental laminin compared to EHS laminin. However, this isoform inhibits the ready formation of adhesion complex-like structures in culture. The laminin isoform found in human placental preparations may therefore modulate corneal epithelial cell motility as opposed to permanent adhesion.

Treatment of persistent corneal epithelial defect by autologous serum application

OBJECTIVE

To evaluate the efficacy of autologous serum application for the treatment of persistent epithelial defect.

DESIGN

Prospective, clinical, noncomparative case series.

PARTICIPANTS

A total of 16 eyes were studied.

INTERVENTION

Autologous serum was prepared from the patients and diluted to 20% by saline. The patients were instructed to use the autologous serum six to ten times a day. The concentration of vitamin A, epidermal growth factor (EGF), and transforming growth factor-beta (TGF-beta) was measured at 1 week and 1 month stored in the refrigerator and 1 month and 3 months in the freezer.

MAIN OUTCOME MEASURES

Time to closure of epithelial defect.

RESULTS

Vitamin A, EGF, and TGF-beta were stable during the 1 month in the refrigerator and 3 months in the freezer. Among 16 persistent epithelial defects, 7 (43.8%) healed within 2 weeks, 3 (18.8%) healed within 1 month, and the remaining 6 (37.5%) did not respond within 1 month. No apparent side effect of autologous serum application was observed.

CONCLUSIONS

Autologous serum application healed 43.8% of persistent defect within 2 weeks and 62.5% within 1 month.

Management of neurotrophic keratopathy

Neurotrophic keratopathy is a degenerative corneal disease caused by an impairment of corneal sensitivity. Lack of the sensory nerve's trophic effect is responsible for the impairment in corneal healing and for the changes on the ocular surface that lead to corneal epithelial deficit, ulcer, and perforation. The etiology and recent advances in understanding of the pathogenetic mechanisms of neurotrophic keratopathy are reviewed here. An accurate history and a clinical examination that covers the function of cranial nerves often identify the cause of the disease. Clinical features and guidelines for the differential diagnosis and treatment are presented. Specific medical and surgical treatments, selected on the basis of clinical staging of the disease, can often halt disease progression. Future developments in medical treatment, including the use of neuropeptide and growth factors, are discussed. The identification of corneal anesthesia associated with an epithelial defect allows appropriate treatment and prevention of progression to stromal lysis and perforation.

Conjunctival grafting for ocular surface disease

The procedure of transplanting healthy conjunctiva onto eyes with damaged ocular surface epithelium was first described by Thoft in 1977. Today, conjunctival autografting is widely used in pterygium surgery and has been shown to be both safe and effective in reducing pterygium recurrence. Several randomized, controlled, clinical trials have been reported in the literature, and conjunctival autografting is now recognized to have an efficacy equal to that of such adjunct therapies as beta-irradiation and mitomycin C, and yet it is safer than these treatments. Recent modifications of the conjunctival autograft include the conjunctival rotation autograft and the inferior conjunctival transposition flap, both of which have been reported to be associated with low rates of recurrence. With the discovery of the role of limbal stem cells in the maintenance and stability of the corneal surface, recent forms of ocular surface transplantation that have supplanted Thoft's conjunctival transplantation procedure include limbal autograft transplantation and limbal allograft transplantation. In addition, the adjunct use of human amniotic membrane in these ocular surface transplantation procedures has improved success and survival rates in the management of ocular surface disease, which still presents significant challenges to clinicians today.

Human corneal epithelial cell adhesion to laminins

PURPOSE

To analyze alpha-integrin mediated adhesion of human corneal epithelial cells to placental and EHS laminin isoforms.

METHODS

Western blot analysis was used to partially characterize commercially available preparations of laminin isolated from the mouse EHS sarcoma and from human placenta. Using the human corneal epithelial cell line HCE-T, adhesion to laminin isoforms and fibronectin was determined using a colorimetric adhesion assay. alpha-integrin sub-unit modulation of corneal epithelial cell interaction with laminin isoforms was analyzed using immunofluorescence microscopy and adhesion assays incorporating functional blocking antibodies.

RESULTS

In short-term adhesion assays, the preferred substrate for HCE-T attachment is placental laminin. Immunofluorescence microscopy reveals that alpha-integrin protein localization patterns are not significantly different in HCE-T interacting with EHS or placental laminin. However, in short-term assays alpha3 integrin plays a major role, and alpha2 integrin a minor role, in mediating HCE-T adhesion to laminin. alpha6 integrin does not appear to mediate adhesion to either substrate.

CONCLUSIONS

These studies demonstrate that human corneal epithelial cells are capable of rapid adhesion to, and enhanced spreading on, laminin isoforms not characteristically resident in the adult corneal basement membrane. This characteristic of human corneal epithelium may explain, at least in part, why amniotic membrane transplantation is proving to be clinically useful for human ocular surface reconstruction.

Suppression of transforming growth factor-beta isoforms, TGF-beta receptor type II, and myofibroblast differentiation in cultured human corneal and limbal fibroblasts by amniotic membrane matrix

Down-regulation of the transforming growth factor-beta (TGF-beta) signaling system is a strategy for preventing scarring during wound healing. Human corneal and limbal fibroblasts were cultured on the stromal matrix side of preserved human amniotic membrane. The levels of TGF-beta1, beta2, and beta3 and TGF-beta type II receptor transcripts and TGF-beta1 and beta2 proteins were suppressed as early as 8 hr and more dramatically at 24 hr after contact with an amniotic membrane. This suppressive effect was accompanied by down-regulation of alpha-smooth muscle actin, EDA spliced form of fibronectin, and integrin alpha5. It persisted even when challenged by 10 ng/ml TGF-beta1. In contrast with their counterparts grown on plastic or in collagen gel, such suppression in amniotic membrane cultures remained complete after 1 week of culturing. Cells cultured on amniotic membrane showed significantly reduced [3H]-thymidine incorporation compared to cells cultured on plastic and displayed no DNA fragmentation. These results reveal a novel mechanism by which the TGF-beta signaling system, DNA synthesis, and subsequent myofibroblast differentiation can be suppressed by an amnionic membrane matrix. This action explains in part the antiscarring results of amniotic membrane transplantation used for ocular surface reconstruction, a surgical technique applicable to other subspecialties. It may also explain in part why fetal wound healing is scarless.

Amniotic membrane transplantation for ocular surface reconstruction

AIMS

To evaluate the efficacy of amniotic membrane transplantation (AMT) for ocular surface reconstruction.

METHODS

10 consecutive patients who underwent AMT were included. The indications were: group A, cases with persistent epithelial defect after corneal abscess (n = 1), radiation (n = 1), or chemical burn (n = 3); group B, cases with epithelial defect and severe stromal thinning and impending or recent perforation, due to chemical burn (two patients, three eyes) or corneal abscess (n = 2); group C, to promote corneal epithelium healing and prevent scarring after symblepharon surgery with extensive corneo-conjunctival adhesion (n = 1). Under sterile conditions amniotic membrane was prepared from a fresh placenta of a seronegative pregnant woman and stored at -70 degrees C. This technique involved the use of amniotic membrane to cover the entire cornea and perilimbal area in groups A and B, and the epithelial defect only in group C.

RESULTS

The cornea healed satisfactorily in four of five patients in group A, but the epithelial defect recurred in one of these patients. After AMT three patients underwent limbal transplantation and one penetrating keratoplasty and cataract extraction. In group B amniotic membrane transplantation was not helpful, and all cases underwent an urgent tectonic corneal graft. Surgery successfully released the symblepharon, promoted epithelialisation and prevented adhesions in the case of group C.

CONCLUSION

AMT was effective to promote corneal healing in patients with persistent epithelial defect, and appeared to be helpful after surgery to release corneo-conjunctival adhesion. Most cases required further surgery for visual and ocular surface rehabilitation. Amniotic membrane used as a patch was not effective to prevent tectonic corneal graft in cases with severe stromal thinning and impending or recent perforation.