Cryopreserved human umbilical cord patch for in-utero spina bifida repair.

OBJECTIVE: To identify a patch system to repair surgically created spina bifida in a sheep model for its efficacy in healing the skin defect, protecting the underlying spinal cord and reducing the Chiari II malformation. METHODS: Spina bifida was created surgically in 16 fetuses from eight timed-pregnant sheep at gestational age of 75 days. Two fetuses did not survive the procedure. Repeat hysterotomy was performed at 95 days' gestation to cover the defect with either biocellulose film with underwater adhesive (BCF-adhesive) (n = 7) or human umbilical cord with suture (HUC-suture) (n = 7). Three fetuses without formation of the defect served as reference controls. The skin healing was examined by direct visualization after a planned Cesarean section at term, followed by histological analysis using hematoxylin and eosin and Masson's trichrome stains. Mid-sagittal sections of the fetal cranium and upper cervical spine were analyzed by a pediatric neuroradiologist who was blinded to the type of patch received. RESULTS: Three fetuses that received the BCF-adhesive and six fetuses that received the HUC-suture survived to term for final analysis. As a result of dislodgment of the BCF-adhesive, all spina bifida defects repaired using BCF-adhesive were not healed and showed exposed spinal cord with leakage of cerebrospinal fluid. In contrast, all spinal defects repaired by HUC-suture were healed with complete regrowth of epidermal, dermal and subdermal tissue components, with no exposed spinal cord. The maximal skin wound width was 21 ± 3.6 mm in the BCF-adhesive group but 3 ± 0.8 mm in the HUC-suture group (P < 0.001). The spinal cord area (P = 0.001) and the number of anterior horn cells (P = 0.03) was preserved to a greater degree in the HUC-suture group than in the BCF-adhesive group, whilst psammoma bodies, signifying neuronal degeneration, were only observed in the BCF-adhesive group. Anatomic changes, indicative of Chiari II malformation, were seen in all three fetuses of the BCF-adhesive group but in none of the HUC-suture group (P < 0.01). CONCLUSION: Cryopreserved umbilical cord graft is a promising regenerative patch for intrauterine repair of spina bifida.

Cryopreserved human amniotic membrane and a bioinspired underwater adhesive to seal and promote healing of iatrogenic fetal membrane defect sites.

INTRODUCTION: We investigated the ability of cryopreserved human amniotic membrane (hAM) scaffold sealed with an underwater adhesive, bio-inspired by marine sandcastle worms to promote healing of iatrogenic fetal membrane defects in a pregnant swine model. METHODS: Twelve Yucatan miniature pigs underwent laparotomy under general anesthesia at 70 days gestation (term = 114 days). The gestational sacs were assigned to uninstrumented (n = 24) and instrumented with 12 Fr trocar, which was further randomized into four different arms-no hAM patch, (n = 22), hAM patch secured with suture (n = 16), hAM patch with no suture (n = 14), and hAM patch secured with adhesive (n = 9). The animals were euthanized 20 days after the procedure. Gross and histological examination of the entry site was performed for fetal membrane healing. RESULTS: There were no differences in fetal survival, amniotic fluid levels, or dye-leakage from the amniotic cavity between the groups. The fetal membranes spontaneously healed in instrumented sacs without hAM patches. In sacs with hAM patches secured with sutures, the patch was incorporated into the swine fetal membranes. In sacs with hAM patches without sutures, 100% of the patches were displaced from the defect site, whereas in sacs with hAM patches secured with adhesive 55% of the patches remained in place and showed complete healing (p = 0.04). DISCUSSION: In contrast to humans, swine fetal membranes heal spontaneously after an iatrogenic injury and thus not an adequate model. hAM patches became incorporated into the defect site by cellular ingrowth from the fetal membranes. The bioinspired adhesive adhered the hAM patches within the defect site.

Comparison of cryopreserved amniotic membrane and umbilical cord tissue with dehydrated amniotic membrane/chorion tissue.

OBJECTIVE: To evaluate how the different processing methods cryopreservation and dehydration affect the structural integrity and biological composition of key signalling molecules within amniotic membrane and umbilical cord tissues. METHOD: We directly compared cryopreserved amniotic membrane (AM) and umbilical cord (UC) tissues with dehydrated amniotic membrane/chorion (dHACM) tissue using biochemical and functional assays including histological and histochemical staining, BCA, agarose gel electrophoresis, western blot, ELISA, and proliferation and cell death assays. RESULTS: Cryopreservation retains the native architecture of the AM/UC extracellular matrix and maintains the quantity and activity of key biological signals present in fresh AM/UC, including high molecular weight hyaluronic acid, heavy chain-HA complex, and pentraxin 3. In contrast, dehydrated tissues were structurally compromised and almost completely lacked these crucial components. CONCLUSION: The results presented here indicate that cryopreservation better preserves the structural and biological signaling molecules of foetal tissues.

Critical appraisal of ex vivo expansion of human limbal epithelial stem cells.

The stem cells (SCs) of the corneal epithelium located in the limbal basal layer are the ultimate source to maintain corneal epithelial homeostasis. Like other adult tissue-specific SCs, self renewal and fate decision of limbal SCs are regulated by a specialized in vivo microenvironment, termed "niche". Loss of limbal SCs or dysfunction of the limbal niche renders corneas with a unique clinical disease labeled limbal stem cell deficiency (LSCD). Besides transplantation of autologous or allogeneic limbal SCs or amniotic membrane, a new strategy of treating LSCD is to transplant a bio-engineered graft by expanding limbal SCs ex vivo. Herein, we conduct a critical appraisal of six protocols that have successfully been practiced in treating human patients with LSCD, and identify issues whether niche regulation has been disrupted or maintained during isolation and expansion. Consequently, we propose a future direction that may circumvent the potential pitfalls existing in these conventional protocols by preserving the interaction between limbal SCs and their native niche cells during isolation and expansion. Such an approach may one day help realize considerable promise held by adult SCs in treating a number of diseases.

Limbal stem cell transplantation: new progresses and challenges.

Patients with limbal stem cell deficiency (LSCD) suffer from photophobia and a severe loss of vision uncorrectable by conventional PKP. This literature review shows that new strategies can be formulated for treating LSCD. Early cryopreserved amniotic membrane transplantation (AMT) as a temporary biological bandage with sutures or with sutureless ProKera in the acute stage of chemical burn and Stevens-Johnson syndrome prevents the occurrence of LSCD by preserving and expanding the remaining limbal epithelial stem cells. Similarly, remaining limbal stem cells can also be expanded in corneal surfaces with partial or nearly total LSCD if corneal pannus is removed and AMT is performed as a graft with or without sutures by the use of fibrin glue. Moreover, AMT as a temporary bandage and a graft using fibrin glue can also facilitate corneal surface reconstruction by reducing the size of a conjunctival limbal autograft (CLAU) to one 60 degrees graft for unilateral total LSCD as well as promote the success of a keratolimbal allograft (KLAL) for bilateral total LSCD. The latter success is further dictated by effective systemic immunosuppression and by measures to restore the ocular surface defenses, suppress conjunctival inflammation, and correct cicatricial complications so that a stable tear film can be maintained before surgery. This review also summarizes recent findings and outlines future challenges that we need to overcome in squamous metaplasia, that is, another major type of ocular surface failure.

Down-regulation of Pax6 is associated with abnormal differentiation of corneal epithelial cells in severe ocular surface diseases.

Pax6 is the universal master control gene for eye morphogenesis. Other than retina and lens, Pax6 also expressed in the ocular surface epithelium from early gestation until the postnatal stage, in which little is known about the function of Pax6. In this study, corneal pannus tissues from patients with ocular surface diseases such as Stevens-Johnson syndrome (SJS), chemical burn, aniridia and recurrent pterygium were investigated. Our results showed that normal ocular surface epithelial cells expressed Pax6. However, corneal pannus epithelial cells from the above patients showed a decline or absence of Pax6 expression, accompanied by a decline or absence of K12 keratin but an increase of K10 keratin and filaggrin expression. Pannus basal epithelial cells maintained nuclear p63 expression and showed activated proliferation, evidenced by positive Ki67 and K16 keratin staining. On 3T3 fibroblast feeder layers, Pax6 immunostaining was negative in clones generated from epithelial cells harvested from corneal pannus from SJS or aniridia, but positive in those from the normal limbal epithelium; whereas western blots showed that some epithelial clones expanded from pannus retained Pax6 expression. Transient transfection of an adenoviral vector carrying EGFP-Pax6 transgenes into these Pax6(-) clones increased both Pax6 and K12 keratin expression. These results indicate that Pax6 helps to maintain the normal corneal epithelial phenotype postnatally, and that down-regulation of Pax6 is associated with abnormal epidermal differentiation in severe ocular surface diseases. Reintroduction of activation of the Pax6 gene might be useful in treating squamous metaplasia of the ocular surface epithelium.

In vitro and in vivo killing of ocular Demodex by tea tree oil.

AIMS: To compare the in vitro killing effect of different agents on Demodex and to report the in vivo killing effect of tea tree oil (TTO) on ocular Demodex. METHODS: Survival time of Demodex was measured under the microscope. Sampling and counting of Demodex was performed by a modified method. RESULTS: Demodex folliculorum survived for more than 150 minutes in 10% povidone-iodine, 75% alcohol, 50% baby shampoo, and 4% pilocarpine. However, the survival time was significantly shortened to within 15 minutes in 100% alcohol, 100% TTO, 100% caraway oil, or 100% dill weed oil. TTO's in vitro killing effect was dose dependent. Lid scrub with 50% TTO, but not with 50% baby shampoo, can further stimulate Demodex to move out to the skin. The Demodex count did not reach zero in any of the seven patients receiving daily lid scrub with baby shampoo for 40-350 days. In contrast, the Demodex count dropped to zero in seven of nine patients receiving TTO scrub in 4 weeks without recurrence. CONCLUSIONS: Demodex is resistant to a wide range of antiseptic solutions. Weekly lid scrub with 50% TTO and daily lid scrub with tea tree shampoo is effective in eradicating ocular Demodex.

Characterisation of myofibroblasts in fibrovascular tissues of primary and recurrent pterygia.

AIMS: To determine the presence and origin of myofibroblasts in pterygia. METHODS: 86 specimens including head, body, and fibrovascular tissue from 52 primary and 34 recurrent pterygia and five exenterated eyes without pterygia were searched for the origin of myofibroblasts. All tissues were subjected to haematoxylin and eosin staining, immunohistochemistry using antibodies against alpha smooth muscle actin (alpha-SMA), desmin, vimentin, and caldesmon, and transmission electron microscopy (TEM). The phenotype of fibroblasts subcultured in a serum free medium from pterygium fibrovascular tissues was characterised by the above antibodies. Bundles of dense fibrous tissues were noted in 86% of the fibrovascular tissue specimens evaluated. Cells within these bundles were characterised as myofibroblasts based on positive staining to alpha-SMA, but negative to desmin and caldesmon, markers for smooth muscle cells. Interestingly, positive alpha-SMA staining was also found in the periorbital fibroadipose tissue posterior to Tenon's capsule near the nasal conjunctiva in all exenterated specimens. All first passage fibroblasts expressed vimentin, some were positive to alpha-SMA, but all were negative to desmin or caldesmon. Cells in pterygium fibrovascular tissues showed ultrastructural features of intracytoplasmic bundles of microfilaments, consistent with myofibroblastic differentiation. CONCLUSION: These studies collectively demonstrate the presence of contractile myofibroblasts bundle in pterygia and in the periorbital fibroadipose tissue posterior to Tenon's capsule of exenterated eyes without pterygium.

Keratolimbal allograft in corneal reconstruction.

The replenishment of corneal epithelial SC is a crucial step for reconstructing the ocular surface in patients suffering from devastating ocular surface diseases manifesting with total LSCD. KLAL is one of such procedures and has a long track record and a long follow-up for patients with bilateral total LSCD. This review summarizes the literature experiences and outline new strategies that are important to enhance the success of this procedure. Further research is needed to fully understand the biological processes involved in allogeneic tissue transplantation for preserving epithelial SC adhesion, migration, and survival.

Rat enterocyte cultures on human amniotic membranes.

BACKGROUND: Rat enterocytes were cultured on human amniotic membranes. METHODS: Intestine of neonatal DA rats was digested using collagenase and dispase according to the technique developed by Evans. The harvested enterocytes were cultured on human amniotic membranes using standard cell culture techniques. RESULTS: After the second day of culture, some intestinal epithelial units started to gradually detach from the membrane, dispersing as single cells and disappearing within a few days. On the contrary, other units showed signs of cell proliferation. The cultured cells underwent morphologic changes, survived, and remained attached to the amniotic membrane for 3 weeks. Paraffin sections of the membrane showed cultured cytokeratin-positive cells attached to the membrane as a monolayer. CONCLUSIONS: Human amniotic cell membranes help to maintain rat enterocytes in culture for a long time period (3 weeks), possibly via secretion of trophic factors. This technique may provide a valuable tool to study the development and the properties of these epithelial cells in a culture environment.

Clinical characteristics of conjunctivochalasis with or without aqueous tear deficiency.

AIM: To show characteristic ocular surface findings caused by conjunctivochalasis (CCh) in dry eye patients with or without aqueous tear deficiency (ATD). DESIGN: Comparative non-interventional cases. PATIENTS AND METHODS: Clinical data of five ATD patients without CCh (group A), eight CCh patients with ATD (group B), and eight CCh patients without ATD (group C) were retrospectively reviewed. Presence or absence of CCh was determined by fluorescein staining to outline tear meniscus and conjunctival folds with an enhancing filter. Dry eye symptoms, history of subconjunctival haemorrhage, meibum expression, tear break up time, fluorescein and rose bengal staining, and fluorescein clearance test, and other abnormal ocular surface findings were measured. RESULTS: CCh patients were significantly older (p = 0.001). In pure ATD, the principal symptom of dryness became worse as the day progressed. In contrast, blurry vision, burning sensation, and dryness became worse during reading in all CCh patients (p = 0.0008) or worse in the morning upon awakening in the majority patients with CCh only (p = 0.02). Besides the interpalpebral exposure, which was noted in ATD, positive fluorescein or rose bengal staining was noted in the redundant conjunctival folds and the non-exposure zone in CCh (p = 0.0008). Redundant conjunctival folds were present in both lower and upper bulbar conjunctiva, obliterating both lower and upper tear meniscuses, and spatially correlated with anterior migration of the mucocutaneous junction in CCh. Delayed tear clearance was significantly more prevalent in CCh than ATD (p = 0.0008). Vigorous blinking worsened in CCh but not in ATD (p = 0.0008). Lacrimal puncta were swollen in groups B and C, but not in group A (p = 0.04). CONCLUSIONS: CCh is not restricted to the lower bulbar conjunctiva, and contributes to pathogenesis of dry eye by obliterating both lower and upper tear meniscus, causing unstable tear film and by creating delayed tear clearance. Dry eye symptoms were worsened by downgaze during reading and by vigorous blinking. Other characteristic signs including subconjunctival haemorrhage, swollen puncta, anterior migration of the mucocutaneous junction, and patterns of dye staining also help distinguish dry eye associated with CCh from that caused by ATD alone.

Correlation of long term phenotypic and clinical outcomes following limbal epithelial transplantation cultivated on amniotic membrane in rabbits.

AIM: To determine the epithelial phenotype in rabbits with total limbal stem cell deficiency (LSCD) after reconstruction with autologous limbal epithelial stem cells ex vivo expanded on rabbit amniotic membrane (AM). METHODS: Left eyes of 52 rabbits were rendered total LSCD, verified by impression cytology. The fibrovascular pannus of each cornea was removed. Group I (n = 10) received rabbit AM transplantation alone, while groups II-IV (n = 42) underwent transplantation of LSC cultured on rabbit AM (LSC-AM) from a small limbal biopsy taken from the right eye. Clinical outcome was graded as "success," "partial success," or "failure" depending on the corneal smoothness and avascularity. Epithelial phenotype was determined by immunostaining and graded as "corneal (K)," "conjunctival (J)," or "mixed (M)" depending on expression of K3 and Muc5AC. RESULTS: After 1 year follow up, group I showed 100% failure and groups II-IV showed 26% success (p<0.001). Clinical failure correlated with J phenotype p = 0.001), while clinical success correlated with K phenotype p = 0.01). When the phenotypic outcome was used for comparison, J phenotype was significantly high in group I (p = 0.003), while K phenotype was significantly high in groups II-IV (p<0.05). CONCLUSION: There is a strong correlation between clinical success and resultant corneal epithelial phenotype. Ex vivo expanded LSC can successfully reconstruct corneal surfaces with unilateral total LSCD.

Corneal stromal changes following reconstruction by ex vivo expanded limbal epithelial cells in rabbits with total limbal stem cell deficiency.

AIM: To study corneal stromal changes and the presence of myofibroblasts after transplantation of ex vivo expanded limbal epithelium. METHODS: A state of limbal deficiency was induced in 16 rabbits. After transplantation with autologous ex vivo expanded limbal epithelium on amniotic membrane (AM), their clinical outcomes were classified as success, partial success or failure according to surface smoothness, stromal clarity, and vascularisation. Clinical outcomes were correlated with phenotypic outcomes of corneal, conjunctival, or mixed epithelium, defined by expression of K3 keratin or MUC5AC. Immunostaining was performed with antibodies against collagen IV, fibronectin, and alpha-smooth muscle actin (alpha-SMA) to assess stromal wound remodelling. RESULTS: Rabbits were sacrificed after a mean follow up of 10 (SD 3.3) months. Collagen IV, expressed in the basement membrane of all three groups, was found in the stroma of the partial success, but not in that of the success or the failure. Fibronectin was absent in the success and the failure, but expressed in the stroma of the partial success. Alpha-SMA was expressed in superficial stroma of the partial success, but suppressed in areas with AM remnants. CONCLUSION: Restoration of a clear and transparent cornea is associated with a normal corneal epithelium and complete wound remodelling. In contrast, wound healing remains active and incomplete in conjunctivalised corneas, which remain opaque with myofibroblasts.

Therapeutic penetrating keratoplasty in severe fungal keratitis using cryopreserved donor corneas.

AIMS: To investigate whether cryopreserved donor cornea could be used for therapeutic penetrating keratoplasty (PKP) to eradicate the infection, obviate complications, and preserve anatomical integrity in severe fungal keratitis. METHODS: In this retrospective, consecutive case series, 45 eyes of 45 patients with severe fungal keratitis, which exhibited anterior chamber collapse, corneal perforation, and/or large suppurative corneal infiltrate, received therapeutic PKP after removal of the infected corneal tissue, irrigation of the anterior chamber by 0.2% fluconazole solution, iris dissection of fibrinoid membrane, and iridectomy and therapeutic PKP using corneas cryopreserved at -20 degrees C. RESULTS: Among 45 eyes, 39 eyes (86.7%) were successfully eradicated the fungal infection without recurrence and maintained their anatomical integrity without any complication. Four of 45 eyes (8.9%) showed postoperative rise of intraocular pressure, of which three were controlled with subsequent antiglaucoma surgeries, whereas one eye needed additional antiglaucoma medications. Two of 45 eyes (4.4%) were enucleated because of uncontrollable fungal infection and secondary retinal detachment, respectively. 23 eyes received subsequent optical PKP and, among them, 21 maintained clear corneal grafts and two suffered from graft failure due to allograft rejections. CONCLUSION: Cryopreserved donor corneas are effective substitutes in therapeutic PKP to control severe fungal corneal infection and preserve the global integrity, and may offer additional advantages over conventional PKP in reducing allograft rejection, eradicating fungal infection during the postoperative period, and improving the success of optical PKP for visual rehabilitation.

Temporary amniotic membrane patching for acute chemical burns.

PURPOSE: To describe the surgical technique, and its usefulness, of temporary amniotic membrane patching (AMP) in the acute phase of ocular chemical injury. METHODS: Temporary AMP with modification in suture placement was performed on five eyes of five consecutive patients inflicted with acute chemical injury having a greater than grade II injury by the Roper-Hall classification. RESULTS: All patients reported herein presented with a large epithelial defect on the cornea and conjunctiva. Case 3 was classified as grade III while the other four cases were classified as grade II. The causative chemical agents were anhydrous acetic acid in Case 1, calcium oxide in Case 2, sodium hydroxide in Case 3, sodium silicate in Case 4, and sulphuric acid in Case 5. All cases experienced rapid relief of pain after AMP. Epithelialization of the cornea with improvement of visual acuity was observed in all cases when the amniotic membrane was removed within 2 weeks after surgery. During the mean follow-up of 19.6 months, the ocular surface remained stable and no cicatricial complications were noted. CONCLUSIONS: These results suggest that immediate AMP is quite useful for managing moderately severe acute ocular chemical injury by facilitating rapid epithelialization and pain relief, and securing ocular surface integrity.

Amniotic membrane transplantation for reconstruction after excision of large ocular surface neoplasias.

AIM: To evaluate the clinical outcome of patients in whom ocular surface reconstruction was performed using amniotic membrane transplantation (AMT) after the excision of large (>20 mm square) ocular surface neoplasias (OSN). METHODS: A non-comparative interventional case series. In 16 eyes of 16 patients, excision of large OSN including conjunctival intraepithelial neoplasia (CIN), primary acquired melanosis, and malignant melanoma was followed by adjunctive cryotherapy and suturing of a single layer of amniotic membrane (AM) with the basement membrane side facing up to the healthy bordering tissue. Epithelial healing, complications, and tumour recurrences were analysed. RESULTS: During a mean follow up of 23.7 (SD 11, range 11-43) months, ocular surface healing was rapid and complete in all cases. One complication of pyogenic granuloma was noted. Tumour recurrence occurred in one out of 10 CIN cases (10%), no recurrences were observed in the patients with melanotic lesions. CONCLUSIONS: AMT in lieu of conjunctival or mucosal autograft is an effective substrate for reconstructing the ocular surface following excision of large OSN. AMT is effective in managing large OSN by avoiding the complications that may be associated with conventional removal, specifically in cases where the limbal architecture is destroyed by surgical resection or adjuvant therapies.

Ex vivo preservation and expansion of human limbal epithelial stem cells on amniotic membrane cultures.

BACKGROUND/AIM: Amniotic membrane (AM) transplantation effectively expands the remaining limbal epithelial stem cells in patients with partial limbal stem cell deficiency. The authors investigated whether this action could be produced ex vivo. METHODS: The outgrowth rate on AM was compared among explants derived from human limbus, peripheral cornea, and central cornea. For outgrowth of human limbal epithelial cells (HLEC), cell cycle kinetics were measured by BrdU labelling for 1 or 7 days, of which the latter was also chased in primary cultures, secondary 3T3 fibroblast cultures, and in athymic Balb/c mice following a brief treatment with a phorbol ester. Epithelial morphology was studied by histology and transmission electron microscopy, and phenotype was defined by immunostaining with monoclonal antibodies to keratins and mucins. RESULTS: Outgrowth rate was 0/22 (0%) and 2/24 (8.3%) for central and peripheral corneal explants, respectively, but was 77/80 (96.2%) for limbal explants (p <0.0001). 24 hour BrdU labelling showed a uniformly low (that is, less than 5%) labelling index in 65% of the limbal explants, but a mixed pattern with areas showing a high (that is, more than 40%) labelling index in 35% of limbal explants, and in all (100%) peripheral corneal explants. Continuous BrdU labelling for 7 days detected a high labelling index in 61.5% of the limbal explants with the remainder still retaining a low labelling index. A number of label retaining cells were noted after 7 day labelling followed by 14 days of chase in primary culture or by 21 days of chase after transplantation to 3T3 fibroblast feeder layers. After exposure to phorbol 12-myristate 13-acetate for 24 hours and 7 day labelling, HLEC transplanted in athymic mice still showed a number of label retaining basal cells after 9 days of chase. HLEC cultured on AM were strongly positive for K14 keratin and MUC4 and slightly positive in suprabasal cells for K3 keratin but negative for K12 keratin, AMEM2, and MUC5AC. After subcutaneous implantation in athymic mice, the resultant epithelium was markedly stratified and the basal epithelial cells were strongly positive for K14 keratin, while the suprabasal epithelial cells were strongly positive for K3 keratin and MUC4, and the entire epithelium was negative for K12 keratin and MUC5A/C. CONCLUSIONS: These data support the notion that AM cultures preferentially preserve and expand limbal epithelial stem cells that retain their in vivo properties of slow cycling, label retaining, and undifferentiation. This finding supports the feasibility of ex vivo expansion of limbal epithelial stem cells for treating patients with total limbal stem cell deficiency using a small amount of donor limbal tissue.