Manufacturing of human corneal endothelial grafts

PURPOSE

Human corneal endothelial cells (HCECs) play a significant role in maintaining visual function. However, these cells are notorious for their limited proliferative capacity in vivo. Current treatment of corneal endothelial dysfunction resorts to corneal transplantation. Herein we describe an ex vivo engineering method to manufacture HCEC grafts suitable for transplantation through reprogramming into neural crest progenitors.

METHODS

HCECs were isolated by collagenase A from stripped Descemet membrane of cadaveric corneoscleral rims, and induced reprogramming via knockdown with p120 and Kaiso siRNAs on collagen IV-coated atelocollagen. Engineered HCEC grafts were released after assessing their identity, potency, viability, purity and sterility. Phase contrast was used for monitoring cell shape, graft size, and cell density. Immunostaining was used to determine the normal HCEC phenotype with expression of N-cadherin, ZO-1, ATPase, acetyl-α-tubulin, γ-tubulin, p75NTR, α-catenin, β-catenin, and F-actin. Stability of manufactured HCEC graft was evaluated after transit and storage for up to 3 weeks. The pump function of HCEC grafts was measured by lactate efflux.

RESULTS

One HCEC graft suitable for corneal transplantation was generated from 1/8th of the donor corneoscleral rim with normal hexagonal cell shape, density, and phenotype. The manufactured grafts were stable for up to 3 weeks at 37 °C or up to 1 week at 22 °C in MESCM medium and after transcontinental shipping at room temperature by retaining normal morphology (hexagonal, >2000 cells/mm2, >8 mm diameter), phenotype, and pump function.

CONCLUSIONS

This regenerative strategy through knockdown with p120 and Kaiso siRNAs can be used to manufacture HCEC grafts with normal phenotype, morphology and pump function following prolonged storage and shipping.

HC-HA/PTX3 from amniotic membrane reverts senescent limbal niche cells to Pax6+ neural crest progenitors to support limbal epithelial progenitors

Quiescence and self‐renewal of human corneal epithelial progenitor/stem cells (LEPC) are regulated by the limbal niche, presumably through close interaction with limbal (stromal) niche cells (LNC). Paired box homeotic gene 6 (Pax6), a conserved transcription factor essential for eye development, is essential for proper differentiation of limbal and corneal epithelial stem cells. Pax6 haploinsufficiency causes limbal stem cell deficiency, which leads to subsequent corneal blindness. We previously reported that serial passage of nuclear Pax6+ LNC resulted in the gradual loss of nuclear Pax6+ and neural crest progenitor status, the latter of which was reverted upon recovery of Pax6. These findings suggest Pax6 plays a pivotal role in supporting the self‐renewal of LEPC in limbal niche. Herein, we show that HC‐HA/PTX3, a unique matrix purified from amniotic membrane (AM) and consists of heavy chain 1of inter‐α‐trypsin inhibitor covalently linked to hyaluronic acid and complexed with pentraxin 3, is capable of reverting senescent LNC to nuclear Pax6+ neural crest progenitors that support self‐renewal of LEPC. Such reversion is causally linked to early cell aggregation mediated by activation of C‐X‐C chemokine receptor type 4 (CXCR4)‐mediated signaling followed by activation of bone morphogenetic protein (BMP) signaling. Furthermore, CXCR4‐mediated signaling, but not BMP signaling, controls recovery of the nuclear Pax6+ neural crest progenitors. These findings not only explain why AM helps in vivo and ex vivo expansion of human LEPC, but they also illuminate the potential role of HC‐HA/PTX3 as a surrogate matrix niche that complements stem cell‐based therapies in regenerative medicine.

HC-HA/PTX3 Purified From Human Amniotic Membrane Reverts Human Corneal Fibroblasts and Myofibroblasts to Keratocytes by Activating BMP Signaling

Purpose

Fibrosis or scarring is a pathological outcome of wound healing and is characterized by terminally differentiated myofibroblasts. Heavy chain-hyaluronic acid/pentraxin 3 (HC-HA/PTX3) is a unique matrix component purified from amniotic membrane that exerts an anti-inflammatory effect. Herein, we investigate whether HC-HA/PTX3 can also exert an antiscarring effect.

Methods

Human corneal fibroblasts and myofibroblasts were seeded on plastic, immobilized HA or HC-HA/PTX3 or on plastic with or without soluble HA and HC-HA/PTX3 in DMEM+10% FBS, with or without AMD3100 or SB431542 in DMEM+ITS with or without transforming growth factor–β1 (TGF-β1). Transcript expression of keratocyte and signaling markers was determined by RT-qPCR. Immunostaining was performed to monitor cytolocalization of signaling markers and α-SMA. Western blotting was used to measure relative protein level.

Results

Human corneal fibroblasts and myofibroblasts cultured in or on HC-HA/PTX3, but not HA, were refrained from cytoplasmic expression of αSMA and nuclear translocation of pSMAD2/3 when challenged with exogenous TGF-β1. Such an antiscarring action by suppressing canonical TGF-β1 signaling was surprisingly accompanied by phenotypic reversal to keratocan-expressing keratocytes through activation of BMP signaling. Further investigation disclosed that such phenotypic reversal was initiated by cell aggregation mediated by SDF1-CXCR4 signaling highlighted by nuclear translocation of CXCR4 and upregulation of CXCR4 transcript and protein followed by activation of canonical BMP signaling.

Conclusions

These findings collectively provide mechanistic understanding explaining how amniotic membrane transplantation exerts an antiscarring action. In addition, HC-HA/PTX3 and derivatives may be developed into a new biologic to treat corneal blindness caused by stromal scar or opacity in the future.

Niche regulation of limbal epithelial stem cells: HC-HA/PTX3 as surrogate matrix niche

Homeostasis of the corneal epithelium is ultimately maintained by stem cells that reside in a specialized microenvironment within the corneal limbus termed palisades of Vogt. This limbal niche nourishes, protects, and regulates quiescence, self-renewal, and fate decision of limbal epithelial stem/progenitor cells (LEPCs) toward corneal epithelial differentiation. This review focuses on our current understanding of the mechanism by which limbal (stromal) niche cells (LNCs) regulate the aforementioned functions of LEPCs. Based on our discovery and characterization of a unique extracellular matrix termed HC-HA/PTX3 (Heavy chain (HC1)-hyaluronan (HA)/pentraxin 3 (PTX3) complex, "-" denotes covalent linkage; "/" denotes non-covalent binding) in the birth tissue, i.e., amniotic membrane and umbilical cord, we put forth a new paradigm that HC-HA/PTX3 serves as a surrogate matrix niche by maintaining the in vivo nuclear Pax6+ neural crest progenitor phenotype to support quiescence and self-renewal but prevent corneal fate decision of LEPCs. This new paradigm helps explain how limbal stem cell deficiency (LSCD) develops in aniridia due to Pax6-haplotype deficiency and further explains why transplantation of HC-HA/PTX3-containing amniotic membrane prevents LSCD in acute chemical burns and Stevens Johnson syndrome, augments the success of autologous LEPCs transplantation in patients suffering from partial or total LSCD, and assists ex vivo expansion (engineering) of a graft containing LEPCs. We thus envisage that this new paradigm based on regenerative matrix HC-HA/PTX3 as a surrogate niche can set a new standard for regenerative medicine in and beyond ophthalmology.

Cryopreserved human umbilical cord versus acellular dermal matrix patches for in utero fetal spina bifida repair in a pregnant rat model

OBJECTIVE

Despite significant improvement in spinal cord function after in utero spina bifida (SB) repair compared with traditional postnatal repair, over half of the children who undergo this procedure do not benefit completely. This lack of benefit has been attributed to closure methods of the defect, with subsequent spinal cord tethering at the repair site. Hence, a regenerative patch or material with antiinflammatory and anti-scarring properties may alleviate comorbidities with improved outcomes. The authors' primary objective was therefore to compare cryopreserved human umbilical cord (HUC) versus acellular dermal matrix (ADM) patches for regenerative repair of in utero SB lesions in an animal model.

METHODS

In vivo studies were conducted in retinoic acid-induced SB defects in fetuses of Sprague-Dawley rats. HUC or ADM patches were sutured over the SB defects at a gestational age of 20 days. Repaired SB defect tissues were harvested after 48-52 hours. Tissue sections were immunofluorescently stained for the presence of neutrophils, macrophages, keratinocytes, meningeal cells, and astrocytes and for any associated apoptosis. In vitro meningeal or keratinocyte cell coculture experiments with the ADM and HUC patches were performed. All experiments were scored quantitatively in a blinded manner.

RESULTS

Neutrophil counts and apoptotic cells were lower in the HUC-based repair group (n = 8) than in the ADM patch repair group (n = 7). In the HUC patch repair group, keratinocytes were present on the outer surface of the patch, meningeal cells were present on the inner surface of the patch adjacent to the neural placode, and astrocytes were noted to be absent. In the ADM patch repair group, all 3 cell types were present on both surfaces of the patch. In vitro studies showed that human meningeal cells grew preferentially on the mesenchymal side of the HUC patch, whereas keratinocytes showed tropism for the epithelial side, suggesting an inherent HUC-based cell polarity. In contrast, the ADM patch studies showed no polarity and decreased cellular infiltration.

CONCLUSIONS

The HUC patch demonstrated reduced acute inflammation and apoptosis together with superior organization in regenerative cellular growth when compared with the ADM patch, and is therefore likely the better patch material for in utero SB defect repair. These properties may make the HUC biomaterial useful as a "meningeal patch" during spinal cord surgeries, thereby potentially reducing tethering and improving on spinal cord function.

Self-Retained Cryopreserved Amniotic Membrane for the Management of Corneal Ulcers

Purpose

To evaluate the clinical outcomes of self-retained cryopreserved amniotic membrane (cAM) for the treatment of corneal ulcers.

Methods

This was a single-center, retrospective review of consecutive patients with non-healing corneal ulcers that underwent treatment with self-retained cAM (PROKERA^® Slim). The primary outcome measure was time to complete corneal epithelialization. Ocular discomfort, corneal staining, corneal signs, and visual acuity were assessed at 1 week, 1 month, 3 months, and 6 months. Complications, adverse events, and ulcer recurrence were also recorded.

Results

A total of 13 eyes (13 patients) with recalcitrant corneal ulcers were included for analysis, 9 (69%) of which progressed from neurotrophic keratitis (NK). Prior to cAM application, patients used conventional treatments such as artificial tears (n = 11), antibiotics (n = 11), ointment (n = 11), steroids (n = 6), and antivirals (n = 3). Self-retained cAMs (n = 1.5 ± 0.8) were placed for 6.8 ± 3.4 days, during which time antibiotics were continued. Four cases (31%) were subsequently treated with bandage contact lens (n = 3) and tarsorrhaphy (n = 1). All corneal ulcers healed in a median of 14 days (range: 4-43). This was accompanied by a significant improvement in ocular discomfort, corneal staining, and corneal signs at 1 week, 1 month, 3 months, and 6 months (P<.05). Recurrence was noted in one case. No adverse events were observed.

Conclusion

Self-retained cAM may be a valuable, in-office treatment option for healing recalcitrant corneal ulcers of various etiologies, especially those with underlying NK. Further prospective, controlled studies are warranted.

Amniotic membrane transplantation for managing dry eye and neurotrophic keratitis

Neurotrophic keratitis (NK), a degenerative disease caused by damage to the trigeminal nerve, abolishes both tearing and blinking reflexes, thus causing the most severe forms of dry eye disease (DED). Conversely, the increasing severity of DED also leads to progressive loss of corneal nerve density, potentially resulting in NK. Both diseases manifest the same spectrum of corneal pathologies including inflammation and corneal epithelial keratitis, which can progress into vision-threatening epithelial defect and stromal ulceration. This review summarizes the current literature regarding outcomes following sutured and sutureless cryopreserved amniotic membrane (AM) in treating DED as well as epithelial defects and corneal ulcers due to underlying NK. These studies collectively support the safety and effectiveness of cryopreserved AM in restoring corneal epithelial health, improving visual acuity in eyes with NK and DED, and alleviating symptomatic DED. Future randomized controlled trials are warranted to validate the above findings and determine whether such clinical efficacy lies in promoting corneal nerve regeneration.

Basic science review of birth tissue uses in ophthalmology

The birth tissue is predominantly comprised of amniotic membrane (AM) and umbilical cord (UC), which share the same cell origin as the fetus. These versatile biological tissues have been used to treat a wide range of conjunctival and corneal conditions since 1940. The therapeutic benefits of the birth tissue stem from its anti-inflammatory and anti-scarring properties that orchestrate regenerative healing. Although the birth tissue also contains many cytokines, growth factors, and proteins, the heavy chain 1-hyaluronic acid/pentraxin 3 (HC-HA/PTX3) matrix has been identified to be a major active tissue component responsible for AM/UC's multifactorial therapeutic actions. HC-HA/PTX3 complex is abundantly present in fresh and cryopreserved AM/UC, but not in dehydrated tissue. In this review, we discuss the tissue anatomy, the molecular mechanism of action based on HC-HA/ PTX3 to explain their therapeutic potentials, and the various forms available in ophthalmology.

Pax 6 Controls Neural Crest Potential of Limbal Niche Cells to Support Self-Renewal of Limbal Epithelial Stem Cells

On ocular surface, corneal epithelial stem cells (SC) reside in limbus between cornea and conjunctiva. Pax6, an evolutionally conserved transcription factor essential for eye development, is expressed in post-natal corneal and limbal epithelia progenitors (LEPC) but not in underlying stroma. Because Pax6 is transiently expressed in developing corneal stroma and a subset of limbal and corneal stromal progenitors, we examined the role of Pax6 in limbal niche cells (LNC) in maintaining the phenotype of neural crest (NC) progenitors to support LEPC. Our results showed that nuclear Pax6 staining was found in freshly isolated LNC but not corneal stromal cells. Serial passaged LNC resulted in gradual loss of nuclear Pax6 (46 kDa) staining and neural crest progenitor status defined by the expression of embryonic SCs and NC markers, neurosphere formation, and differentiation into neurons, oligodendrocytes and astrocytes. Gain of function of 46 kDa Pax6 in late-passaged LNC resulted in nuclear Pax6 staining and promotion of the aforementioned NC progenitor status. In an in vitro reunion assay, early passaged LNC and late passaged LNC with overexpression of Pax6 inhibited the expression of corneal epithelial differentiation marker and promoted holoclone by LEPC. Therefore, expression of nuclear 46 kDa Pax6 in LNC plays an important developmental role in maintaining NC progenitor status to support self-renewal of corneal epithelial SCs in the limbal niche.

Safety and efficacy of 4-terpineol against microorganisms associated with blepharitis and common ocular diseases

OBJECTIVE

Microbial infection has been reported to cause blepharitis, conjunctivitis and keratitis. We evaluated the safety and efficacy of a foam formulation of 2% 4-terpineol (T4O) against common ocular microorganisms.

MATERIAL AND METHODS

The antimicrobial effect of a 2% T4O formulation was evaluated by the United States Pharmacopeia 51 (USP <51>) antimicrobial effectiveness test for 14 and 28 days, as well as by a Time Kill Study (ASTM E2315) with a 60 s exposure time. Its potential of causing skin and ocular irritation was evaluated by the Repeated Insult Patch Test and the Hen's Egg Chorioallantoic Membrane Test, respectively.

RESULTS AND DISCUSSION

It was seen that 2% T4O formulation did not cause ocular irritation, skin irritation, sensitisation or allergic contact dermatitis in human subjects. Most importantly, it killed microorganisms listed in USP <51> at both 14 and 28 days and exerted a rapid killing effect within 60 s against 13 bacteria, 1 fungus and Acanthamoeba castellanii.

CONCLUSION

The above finding suggests that 2% T4O formulation is safe and effective in killing microorganisms related to common ocular and skin infective diseases.

TRANSLATIONAL RELEVANCE

Although the clinical efficacy in treating ocular disease was not directly studied; this foam formulation containing 2% T4O, based on the in vitro results of this work, demonstrated that it can potentially be used as a preservative-free cleansing agent for ocular hygiene maintenance due to its ability to exert a broad-spectrum antimicrobial effect without causing ocular or skin irritation.

Self-Retained Amniotic Membrane Combined With Antiviral Therapy for Herpetic Epithelial Keratitis

PURPOSE

To evaluate the therapeutic benefit of self-retained cryopreserved amniotic membrane in conjunction with oral antiviral therapy in herpetic epithelial keratitis.

METHODS

Retrospective review of 4 patients with primary (1 eye) and recurrent (3 eyes) unilateral herpetic epithelial keratitis treated with cryopreserved amniotic membrane through the placement of the PROKERA Slim (PKS) (Bio-Tissue, Inc) in conjunction with oral acyclovir. Their symptoms, conjunctival inflammation, corneal staining, and visual acuity were compared before and after treatment.

RESULTS

Herpetic epithelial keratitis presented as dendritic (3 eyes) and geographic (1 eye) epithelial lesions. After epithelial debridement and placement of the PKS for 5 ± 3.7 days, all patients reported significant relief of symptoms, rapid corneal epithelialization, and reduction of ocular surface inflammation. The visual acuity was also improved in all eyes from 0.7 ± 0.7 to 0.4 ± 0.7 logarithm of the minimum angle of resolution (P = 0.2). They remained symptom-free during a follow-up period of 2.7 to 50.8 (20.3 ± 21.7) months.

CONCLUSIONS

The PKS in conjunction with oral acyclovir facilitates the ease of early intervention to accelerate restoration of a normal corneal epithelium in herpetic epithelial keratitis.

Significant correlation between meibomian gland dysfunction and keratitis in young patients with Demodex brevis infestation

Aims

To report the clinical characteristics and correlation between meibomian gland dysfunction (MGD) and keratitis in young patients with ocular demodicosis.

Methods

Observational case series of 60 patients younger than 35 years with ocular demodicosis, of which the diagnosis was based on microscopic counting of Demodex folliculorum and D. brevis of epilated lashes. Severity of keratitis and MGD was graded by photography and meibography, respectively, in a masked fashion.

Results

MGD was detected in 54/60 (90%) patients with the loss of meibomian gland in the upper lid more than the lower lid (p<0.001). Blepharoconjunctivitis and a variety of corneal pathologies were noted in 47/60 (78.3%) and 39/60 (65%) patients, respectively. For a total of 120 eyes, normal cornea was noted in 53 (44.2%) eyes, superficial punctate keratitis or limbitis was noted in 17 (14.2%), while corneal stromal infiltration was found in 50 (41.7%) eyes. Both univariate and multivariate analyses showed that the severity of meibomian gland loss was significantly correlated with higher D. brevis count and more severe keratitis (all p<0.05). Rapid resolution of keratitis and blepharoconjunctivitis was accompanied by significant reduction of the Demodex count in 48 patients receiving lid scrub directed to kill mites.

Conclusions

There is a significant correlation between MGD and keratitis in young patients with ocular demodicosis especially inflicted by D. brevis.

Descemet's Membrane Supports Corneal Endothelial Cell Regeneration in Rabbits

Descemet’s membrane (DM) helps maintain phenotype and function of corneal endothelial cells under physiological conditions, while little is known about the function of DM in corneal endothelial wound healing process. In the current study, we performed in vivo rabbit corneal endothelial cell (CEC) injury via CEC scraping, in which DM remained intact after CECs removal, or via DM stripping, in which DM was removed together with CECs. We found rabbit corneas in the CEC scraping group healed with transparency restoration, while there was posterior fibrosis tissue formation in the corneas after DM stripping on day 14. Following CEC scraping on day 3, cells that had migrated toward the central cornea underwent a transient fibrotic endothelial-mesenchymal transition (EMT) which was reversed back to an endothelial phenotype on day 14. However, in the corneas injured via DM stripping, most of the cells in the posterior fibrosis tissue did not originate from the corneal endothelium, and they maintained fibroblastic phenotype on day 14. We concluded that corneal endothelial wound healing in rabbits has different outcomes depending upon the presence or absence of Descemet’s membrane. Descemet’s membrane supports corneal endothelial cell regeneration in rabbits after endothelial injury.

Topical Cryopreserved Amniotic Membrane and Umbilical Cord Eye Drops Promote Re-Epithelialization in a Murine Corneal Abrasion Model

Purpose

To evaluate morselized amniotic membrane and umbilical cord (AMUC) eye drops in promoting corneal re-epithelialization.

Methods

Following a 2-mm diameter central epithelial wound in one eye of 48 normal C57BL/6 mouse corneas, 10 μL of saline with (n = 24) or without (n = 24) AMUC was applied three times a day for 6 days. The corneal epithelial defect was measured using 0.1% fluorescein, while corneal epithelial regularity was measured by assessment of a reflected light off the corneal surface. Hematoxylin and eosin and immunohistochemistry was performed for Ki-67, CD45, βIII-tubulin, and keratin12. Safety and toxicity were also assessed by monitoring physical activity and body weight.

Results

Compared with the vehicle saline control, AMUC resulted in a significantly smaller corneal epithelial defect at 12 hours (P = 0.002), 1 day (P = 0.016), and 2 days (P = 0.04) post abrasion. Amniotic membrane and umbilical cord also achieved a more rapid complete epithelialization (3.15 ± 1.44 vs. 4.00 ± 1.63 days, P = 0.06) and induced a higher incidence of corneal regularity without affecting physical activity and body weight. Spearman correlation showed that epithelialization was significantly correlated with treatment groups (P < 0.001), time (P < 0.001), and corneal regularity (P = 0.04). Amniotic membrane and umbilical cord significantly decreased CD45+ cell infiltration in the peripheral cornea (P < 0.05) and promoted Ki-67+ cells in the central corneal epithelium (P < 0.05).

Conclusion

Topical AMUC significantly promotes corneal epithelialization and restores corneal regularity by reducing inflammation and promoting proliferation in a murine model of corneal abrasion without causing safety or toxicity concerns. This encouraging preclinical finding warrants a controlled human trial in the future.

Cryopreserved Human Umbilical Cord for In Utero Myeloschisis Repair

BACKGROUND

There is an urgent need is for a regenerative patch for in utero repair of spina bifida in situations in which primary closure is difficult.

CASES

We present two cases of large myeloschisis defects that underwent in utero spina bifida repair at midgestation with closure of the skin defect by using a cryopreserved human umbilical cord patch. The pregnancies were uncomplicated, and the births occurred at 37 weeks by planned cesarean delivery. The repair sites were intact with no evidence of cerebrospinal fluid leakage, with skin regenerated after delivery over a period of 3-4 weeks. The short-term outcomes after delivery showed reversal of hindbrain herniation, minimal spinal cord tethering, and normal function of the lower extremities.

CONCLUSION

Cryopreserved human umbilical cord may be a suitable patch system for the spina bifida closure.

Cryopreserved human umbilical cord versus biocellulose film for prenatal spina bifida repair in a physiologic rat model

BACKGROUND

Prenatal spina bifida (SB) repair with a regenerative patch may improve neurological outcomes by decreasing inflammatory scarring.

OBJECTIVE

This study aims to compare cryopreserved human umbilical cord (HUC) and biocellulose film (BCF) patches sutured over SB lesions for regeneration of native cells and inflammatory response.

STUDY DESIGN

Sprague-Dawley rats were gavaged with retinoic acid (RA) on embryonic day 10 to induce SB. Hysterotomy was performed on embryonic day 20 and on HUC or BCF patches sutured over the defect. Pups were harvested 30 to 34 h later, and hematoxylin and eosin staining and Trichrome staining assessed basic cellular migration. Immunohistochemistry demonstrated the exact nature of the cellular migration. Patches and surrounding exudates were evaluated with microscopy and cells quantified.

RESULTS

Histology showed cellular migration with all HUC patches compared with none with BCF patches. Epithelial cells were noted migrating over the dorsal HUC surface, astrocytes were noted along the HUC surface adjacent to the lesion, and endothelial cells were noted within the HUC. HUC patches showed minimal inflammatory cells. Exudates surrounding the HUC patches had fewer inflammatory cells than exudates around BCF patches.

CONCLUSION

HUC promotes cellular migration of native cells with minimal inflammatory response compared with BCF. HUC may be the superior patch material for prenatal SB repair. © 2017 John Wiley & Sons, Ltd.

Inhibition of Proliferation and Epithelial Mesenchymal Transition in Retinal Pigment Epithelial Cells by Heavy Chain-Hyaluronan/Pentraxin 3

Proliferative vitreoretinopathy (PVR) is mediated by proliferation and epithelial mesenchymal transition (EMT) of retinal pigment epithelium (RPE). Because heavy chain-hyaluronic acid/pentraxin 3 (HC-HA/PTX3) purified from human amniotic membrane exerts anti-inflammatory and anti-scarring actions, we hypothesized that HC-HA/PTX3 could inhibit these PVR-related processes in vitro. In this study, we first optimized an ARPE-19 cell culture model to mimic PVR by defining cell density, growth factors, and cultivation time. Using this low cell density culture model and HA as a control, we tested effects of HC-HA/PTX3 on the cell viability (cytotoxicity), proliferation (EGF + FGF-2) and EMT (TGF-β1). Furthermore, we determined effects of HC-HA/PTX3 on cell migration (EGF + FGF-2 + TGF-β1) and collagen gel contraction (TGF-β1). We found both HA and HC-HA/PTX3 were not toxic to unstimulated RPE cells. Only HC-HA/PTX3 dose-dependently inhibited proliferation and EMT of stimulated RPE cells by down-regulating Wnt (β-catenin, LEF1) and TGF-β (Smad2/3, collagen type I, α-SMA) signaling, respectively. Additionally, HA and HC-HA/PTX3 inhibited migration but only HC-HA/PTX3 inhibited collagen gel contraction. These results suggest HC-HA/PTX3 is a non-toxic, potent inhibitor of proliferation and EMT of RPE in vitro, and HC-HA/PTX3’s ability to inhibit PVR formation warrants evaluation in an animal model.

Heavy Chain-Hyaluronan/Pentraxin 3 from Amniotic Membrane Suppresses Inflammation and Scarring in Murine Lacrimal Gland and Conjunctiva of Chronic Graft-versus-Host Disease

Chronic graft-versus-host disease (cGVHD) is a major complication of hematopoietic stem cell transplantation. Dry eye disease is the prominent ocular sequel of cGVHD and is caused by excessive inflammation and fibrosis in the lacrimal glands. Heavy chain-Hyaluronan/Pentraxin 3 (HC-HA/PTX3) is a complex purified from human amniotic membrane (AM) and known to exert anti-inflammatory and anti-scarring actions. In this study, we utilized a mouse model of cGVHD to examine whether HC-HA/PTX3 could attenuate dry eye disease elicited by cGVHD. Our results indicated that subconjunctival and subcutaneous injection of HC-HA/PTX3 preserved tear secretion and conjunctival goblet cell density and mitigated inflammation and scarring of the conjunctiva. Such therapeutic benefits were associated with suppression of scarring and infiltration of inflammatory/immune cells in the lacrimal glands. Furthermore, HC-HA/PTX3 significantly reduced the extent of infiltration of CD45⁺ CD4⁺ IL-17⁺ cells, CD45⁺ CD34⁺ collagen I⁺ CXCR4⁺ fibrocytes, and HSP47⁺ activated fibroblasts that were accompanied by upregulation of collagen type Iα1, collagen type IIIα1 and NF-kB in lacrimal glands. Collectively, these pre-clinical data help prove the concept that subcutaneous and subconjunctival injection of HC-HA/PTX3 is a novel approach to prevent dry eye disease caused by cGVHD and allow us to test its safety and efficacy in future human clinical trials.

Efficacy of Particulate Amniotic Membrane and Umbilical Cord Tissues in Attenuating Cartilage Destruction in an Osteoarthritis Model

Osteoarthritis (OA) is a progressive degenerative joint disease, and to date, no disease-modifying OA drug exists. Amniotic membrane and umbilical cord products have been used clinically in several diseases due to their anti-inflammatory and antiscarring properties. In the present study, we sought to evaluate whether a particulate amniotic membrane and umbilical cord (AM/UC) matrix could aid in attenuating disease progression. Lewis rats underwent medial meniscus transection (MMT) to induce OA. Two weeks after surgery, animals received intra-articular injections (50 μL) of either 50 or 100 μg/μL particulate AM/UC or saline control and were subsequently euthanized 1 or 4 weeks later. Cartilage degeneration was assessed using both histological scoring methods and equilibrium partitioning of an ionic contrast agent-microcomputed tomography (EPIC-μCT). EPIC-μCT analysis demonstrated that overall cartilage destruction was attenuated, with a significant increase in both cartilage thickness and volume as well as a significant decrease in total lesion area in animals injected with either dose of particulate AM/UC at 1 week, but only a high dose at 4 weeks postinjection. Osteoarthritis Research Society International (OARSI) histology scores of tibial sections corroborated EPIC-μCT results. Overall joint destruction was attenuated in animals injected with either dose of AM/UC tissue compared with saline-injected control animals at 1 week postinjection. Only high-dose AM/UC-injected animals continued to show less overall joint destruction by 4 weeks postinjection. Intra-articular injection of particulate AM/UC tissue attenuates cartilage degradation in a rat MMT model of OA, suggesting that it may be able to slow joint destruction in patients with OA.

Neurological Outcomes after Human Umbilical Cord Patch for In Utero Spina Bifida Repair in a Sheep Model

OBJECTIVES

The objective of our study was to test the hypothesis that in utero repair of surgically created spina bifida in a sheep model using cryopreserved human umbilical cord (HUC) patch improves neurological outcome.

METHODS

Spina bifida with myelotomy was surgically created in timed pregnant ewes at gestational day (GD) 75. The fetuses were randomly assigned to unrepaired versus HUC and treated at GD 95 and then delivered at GD 140. Neurological evaluation was performed using the Texas Spinal Cord Injury Scale (TSCIS), bladder control using ultrasound, and the hindbrain herniation.

RESULTS

Three lambs without the spina bifida creation served as controls. There were four lambs with spina bifida: two were unrepaired and two underwent HUC repair. The control lambs had normal function. Both unrepaired lambs had nonhealed skin lesions with leakage of cerebrospinal fluid, a 0/20 TSCIS score, no bladder control, and the hindbrain herniation. In contrast, both HUC lambs had a completely healed skin defect and survived to day 2 of life, a 3/20 and 4/20 TSCIS score (nociception), partial bladder control, and normal hindbrain anatomy.

CONCLUSIONS

Cryopreserved HUC patch appears to improve survival and neurological outcome in this severe form of the ovine model of spina bifida.

Morselized Amniotic Membrane Tissue for Refractory Corneal Epithelial Defects in Cicatricial Ocular Surface Diseases

Purpose

To evaluate the clinical efficacy of morselized amniotic membrane and umbilical cord tissue (MAU) in treating refractory corneal epithelial defect in ocular cicatricial diseases.

Methods

Retrospective review of four patients with ocular cicatricial diseases treated with topical MAU for corneal epithelial defects refractory to conventional treatments including topical lubricants, autologous serum, bandage contact lens, and tarsorraphy. Their symptoms, corneal staining, conjunctival inflammation, and visual acuity were compared before and after treatment.

Results

After topical application of MAU twice daily, two patients demonstrated rapid corneal epithelialization with prompt visual acuity improvement at the first day. All patients showed corneal epithelialization in 7.3 ± 2.6 days accompanied by a significant relief of symptoms, reduction of ocular surface inflammation, and improvement of visual acuity.

Conclusion

This pilot study suggests topical MAU can be developed into a novel treatment for treating refractory corneal epithelial defects.

Translational Relevance

Topical MAU can be an effective novel treatment for refractory corneal epithelial defects.

HC-HA/PTX3 Purified From Amniotic Membrane as Novel Regenerative Matrix: Insight Into Relationship Between Inflammation and Regeneration

PURPOSE

Human limbal palisade of Vogt is an ideal model for studying and practicing regenerative medicine due to their accessibility. Nonresolving inflammation is a common manifestation of limbal stem cell deficiency, which is the major cause of corneal blindness, and presents as a threat to the success of transplanted limbal epithelial stem cells. Clinical studies have shown that the efficacy of transplantation of limbal epithelial stem cells can be augmented by transplantation of cryopreserved human amniotic membrane (AM), which exerts anti-inflammatory, antiscarring, and antiangiogenic action to promote wound healing.

METHODS

Review of published data to determine the molecular action mechanism explaining how AM exerts the aforementioned therapeutic actions.

RESULTS

From the water-soluble extract of cryopreserved AM, we have biochemically purified one novel matrix component termed heavy chain (HC)-hyaluronan (HA)/pentraxin 3 (PTX3) as the key relevant tissue characteristic responsible for the aforementioned AM's efficacy. Heavy chain-HA is a complex formed by a covalent linkage between HA and HC1 of inter-α-trypsin inhibitor (IαI) by tumor necrosis factor-stimulated gene-6 (TSG-6). This complex may then be tightly associated with PTX3 to form HC-HA/PTX3 complex. Besides exerting an anti-inflammatory, antiscarring, and antiangiogenic effects, HC-HA/PTX3 complex also uniquely maintains limbal niche cells to support the quiescence of limbal epithelial stem cells.

CONCLUSIONS

We envision that HC-HA/PTX3 purified from AM can be used as a unique substrate to refine ex vivo expansion of limbal epithelial stem cells by maintaining stem cell quiescence, self-renewal and fate decision. Furthermore, it can also be deployed as a platform to launch new therapeutics in regenerative medicine by mitigating nonresolving inflammation and reinforcing the well-being of stem cell niche.

Acute and Chronic Ophthalmic Involvement in Stevens-Johnson Syndrome/Toxic Epidermal Necrolysis - A Comprehensive Review and Guide to Therapy. II. Ophthalmic Disease

Our purpose is to comprehensively review the state of the art with regard to Stevens- Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN), with particular attention to improving the management of associated ocular surface complications. SJS and TEN are two ends of a spectrum of immune-mediated disease, characterized in the acute phase by a febrile illness followed by skin and mucous membrane necrosis and detachment. Part I of this review focused on the systemic aspects of SJS/TEN and was published in the January 2016 issue of this journal. The purpose of Part II is to summarize the ocular manifestations and their management through all phases of SJS/TEN, from acute to chronic. We hope this effort will assist ophthalmologists in their management of SJS/TEN, so that patients with this complex and debilitating disease receive the best possible care and experience the most optimal outcomes in their vision and quality of life.

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.

LIF-JAK1-STAT3 signaling delays contact inhibition of human corneal endothelial cells

Human corneal endothelial cells (HCECs) responsible for corneal transparency have limited proliferative capacity in vivo because of "contact-inhibition." This feature has hampered the ability to engineer HCECs for transplantation. Previously we have reported an in vitro model of HCECs in which contact inhibition was re-established at Day 21, even though cell junction and cell matrix interaction were not perturbed during isolation. Herein, we observe that such HCEC monolayers continue to expand and retain a normal phenotype for 2 more weeks if cultured in a leukemia inhibitory factor (LIF)-containing serum-free medium. Such expansion is accompanied initially by upregulation of Cyclin E2 colocalized with nuclear translocation of phosphorylated retinoblastoma tumor suppressor (p-Rb) at Day 21 followed by a delay in contact inhibition through activation of LIF-Janus kinase1 (JAK1)-signal transducer and activator of transcription 3 (STAT3) signaling at Day 35. The LIF-JAK1-STAT3 signaling is coupled with upregulation of E2F2 colocalized with nuclear p-Rb and with concomitant downregulation of p16(INK4a), of which upregulation is linked to senescence. Hence, activation of LIF-JAK1-STAT3 signaling to delay contact inhibition can be used as another strategy to facilitate engineering of HCEC grafts to solve the unmet global shortage of corneal grafts.

Niche Regulation of Limbal Epithelial Stem Cells: Relationship between Inflammation and Regeneration

Human limbal palisades of Vogt are the ideal site for studying and practicing regenerative medicine due to their accessibility. Nonresolving inflammation in limbal stroma is common manifestation of limbal stem cell (SC) deficiency and presents as a threat to the success of transplanted limbal epithelial SCs. This pathologic process can be overcome by transplantation of cryopreserved human amniotic membrane (AM), which exerts anti-inflammatory, antiscarring and anti-angiogenic action to promote wound healing. To determine how AM might exert anti-inflammation and promote regeneration, we have purified a novel matrix, HC-HA/PTX3, responsible for the efficacy of AM efficacy. HC-HA complex is covalently formed by hyaluronan (HA) and heavy chain 1 (HC1) of inter-α-trypsin inhibitor by the catalytic action of tumor necrosis factor-stimulated gene-6 (TSG-6) and are tightly associated with pentraxin 3 (PTX3) to form HC-HA/PTX3. In vitro reconstitution of the limbal niche can be established by reunion between limbal epithelial progenitors and limbal niche cells on different substrates. In 3-dimensional Matrigel, clonal expansion indicative of SC renewal is correlated with activation of canonical Wnt signaling and suppression of canonical bone morphogenetic protein (BMP) signaling. In contrast, SC quiescence can be achieved in HC-HA/PTX3 by activation of canonical BMP signaling and non-canonical planar cell polarity (PCP) Wnt signaling, but suppression of canonical Wnt signaling. HC-HA/PTX3 is a novel matrix mitigating nonresolving inflammation and restoring SC quiescence in the niche for various applications in regenerative medicine.

Stevens-Johnson Syndrome/Toxic Epidermal Necrolysis--A Comprehensive Review and Guide to Therapy. I. Systemic Disease

The intent of this review is to comprehensively appraise the state of the art with regard to Stevens Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN), with particular attention to the ocular surface complications and their management. SJS and TEN represent two ends of a spectrum of immune-mediated, dermatobullous disease, characterized in the acute phase by a febrile illness followed by skin and mucous membrane necrosis and detachment. The widespread keratinocyte death seen in SJS/TEN is rapid and irreversible, and even with early and aggressive intervention, morbidity is severe and mortality not uncommon. We have divided this review into two parts. Part I summarizes the epidemiology and immunopathogenesis of SJS/TEN and discusses systemic therapy and its possible benefits. We hope this review will help the ophthalmologist better understand the mechanisms of disease in SJS/TEN and enhance their care of patients with this complex and often debilitating disease. Part II (April 2016 issue) will focus on ophthalmic manifestations.

Accelerated Restoration of Ocular Surface Health in Dry Eye Disease by Self-Retained Cryopreserved Amniotic Membrane

PURPOSE

To evaluate the clinical efficacy of self-retained cryopreserved amniotic membrane in treating dry eye disease.

METHODS

Retrospective review of 10 patients treated with self-retained cryopreserved amniotic membrane (PROKERA® Slim [PKS], Bio-Tissue, Miami, FL) for moderate-to-severe dry eye refractory to conventional maximal medical treatments. Patients' symptoms, use of medications, conjunctival inflammation, corneal staining, and visual acuity were compared before and after treatment.

RESULTS

PKS was placed in 15 eyes of the 10 patients for 4.9 ± 1.5 days. All patients experienced symptomatic relief for a period of 4.2 ± 4.7 months (P<.001). Such improvement was accompanied by reduction of OSDI scores (P<.001), use of topical medications (P<.001), conjunctival hyperemia (P<.001), corneal staining (P<.001), and improvement of the visual acuity (P=.06). Linear regression analysis estimated that the optimal duration of PKS placement was 5 days to achieve an average symptom-free duration of 4 months in patients with dry eye. Surprisingly, PKS placement also generated improvement in the contralateral eyes.

CONCLUSION

This pilot study suggests that self-retained cryopreserved amniotic membrane via PKS can be used to treat moderate dry eye diseases and warrants further prospective controlled studies.

HC-HA/PTX3 Purified From Amniotic Membrane Promotes BMP Signaling in Limbal Niche Cells to Maintain Quiescence of Limbal Epithelial Progenitor/Stem Cells

To explore how limbal niche cells (LNCs) may control quiescence, self-renewal, and corneal epithelial lineage commitment/differentiation of limbal epithelial progenitor/stem cells (LEPCs), we have established an in vitro sphere assay by reunion between the two cell types in three-dimensional Matrigel. The resultant sphere exhibits inhibition of corneal epithelial lineage commitment/differentiation and marked clonal growth of LEPCs, of which the latter is correlated with activation of canonical Wnt signaling. Herein, we have created a similar reunion assay in immobilized heavy chain-hyaluronic acid/pentraxin 3 (HC-HA/PTX3), which is purified from amniotic membrane (AM) and consists of a complex formed by hyaluronic covalently linked to heavy chain 1 of inter-α-inhibitor and noncovalently linked to pentraxin 3. The resultant spheres exhibited similar suppression of corneal epithelial lineage commitment/differentiation but upregulation of quiescence markers including nuclear translocation of Bmi-1, and negligible clonal growth of LEPCs. This outcome was correlated with the suppression of canonical Wnt but activation of noncanonical (Planar cell polarity) Wnt signaling as well as BMP signaling in both LEPCs and LNCs. The activation of BMP signaling in LNCs was pivotal because nuclear translocation of pSmad1/5/8 was prohibited in hLEPCs when reunioned with mLNCs of conditionally deleted Bmpr1a;Acvr1(DCKO) mice. Furthermore, ablation of BMP signaling in LEPCs led to upregulation of cell cycle genes, downregulation of Bmi-1, nuclear exclusion of phosphorylated Bmi-1, and marked promotion of the clonal growth of LEPCs. Hence, HC-HA/PTX3 uniquely upregulates BMP signaling in LNCs which leads to BMP signaling in LEPCs to achieve quiescence, helping explain how AM transplantation is clinically useful to be used as a matrix for ex vivo expansion of LEPCs and to treat corneal blindness caused by limbal stem cells deficiency.

Engineering of Human Corneal Endothelial Grafts

Human corneal endothelial cells (HCEC) play a pivotal role in maintaining corneal transparency. Unlike in other species, HCEC are notorious for their limited proliferative capacity in vivo after diseases, injury, aging, and surgery. Persistent HCEC dysfunction leads to sight-threatening bullous keratopathy with either an insufficient cell density or retrocorneal membrane due to endothelial-mesenchymal transition (EMT). Presently, the only solution to restore vision in eyes inflicted with bullous keratopathy or retrocorneal membrane relies upon transplantation of a cadaver human donor cornea containing a healthy corneal endothelium. Due to a severe global shortage of donor corneas, in conjunction with an increasing trend toward endothelial keratoplasty, it is opportune to develop a tissue engineering strategy to produce HCEC grafts. Prior attempts of producing these grafts by unlocking the contact inhibition-mediated mitotic block using trypsin-EDTA and culturing of single HCEC in a bFGF-containing medium run the risk of losing the normal phenotype to EMT by activating canonical Wnt signaling and TGF-β signaling. Herein, we summarize our novel approach in engineering HCEC grafts based on selective activation of p120-Kaiso signaling that is coordinated with activation of Rho-ROCK-canonical BMP signaling to reprogram HCEC into neural crest progenitors. Successful commercialization of this engineering technology will not only fulfill the global unmet need but also encourage the scientific community to re-think how cell-cell junctions can be safely perturbed to uncover novel therapeutic potentials in other model systems.

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.

Activation of RhoA-ROCK-BMP signaling reprograms adult human corneal endothelial cells

Activation of RhoA-ROCK-BMP signaling reprograms adult human corneal endothelial cells into neural crest–like progenitors, which effectively form corneal endothelial monolayers that may eliminate the need for corneal transplantation.

Currently there are limited treatment options for corneal blindness caused by dysfunctional corneal endothelial cells. The primary treatment involves transplantation of healthy donor human corneal endothelial cells, but a global shortage of donor corneas necessitates other options. Conventional tissue approaches for corneal endothelial cells are based on EDTA-trypsin treatment and run the risk of irreversible endothelial mesenchymal transition by activating canonical Wingless-related integration site (Wnt) and TGF-β signaling. Herein, we demonstrate an alternative strategy that avoids disruption of cell–cell junctions and instead activates Ras homologue gene family A (RhoA)–Rho-associated protein kinase (ROCK)–canonical bone morphogenic protein signaling to reprogram adult human corneal endothelial cells to neural crest–like progenitors via activation of the miR302b-Oct4-Sox2-Nanog network. This approach allowed us to engineer eight human corneal endothelial monolayers of transplantable size, with a normal density and phenotype from one corneoscleral rim. Given that a similar signal network also exists in the retinal pigment epithelium, this partial reprogramming approach may have widespread relevance and potential for treating degenerative diseases.

Isolation and characterization of mesenchymal progenitor cells from human orbital adipose tissue

PURPOSE

Adipose-derived stem cells (ASCs) have gained importance due to their myriad potential clinical applications. We hypothesize that progenitor cells also exist besides those conventionally isolated from the stromal vascular fraction (SVF).

METHOD

Central and medial orbital adipose tissues obtained from patients during eyelid surgery were digested with collagenase for 3 or 16 hours at 37°C with or without shaking. After centrifugation, the remaining cell pellet was resuspended and filtered to yield flow through in SVF and retained cells (RC) on the filter. Single cells from RC and SVF were cultured on 5% coated Matrigel in serum-free modified embryonic stem cells medium (MESCM) for 10 passages. The progenitor status was evaluated by the expression of a number of markers by qPCR and immunofluorescence staining as well as their plasticity for endothelial and tri-lineage differentiation.

RESULTS

Type I collagenase digestion for 3 hours under shaking was significantly less effective in releasing progenitor cells than collagenase A digestion for 16 hours without shaking. Following filtration, cells in SVF and RC, of which the latter were tangled in collagen IV-containing matrix, expressed different markers of progenitor cells. Cells from SVF and RC could be expanded for 10 passages on coated Matrigel in MESCM and exhibited similar or better potential to differentiate into vascular endothelial cells, chondrocytes, osteocytes, and adipocytes than SVF cells expanded on plastic in Dulbecco's modified Eagle's medium (DMEM) with 10% fetal bovine serum (FBS).

CONCLUSIONS

Different progenitor cells can be isolated and expanded from orbital adipose tissues. Further characterization of their mesodermal or neuroectodermal origin might enhance clinical outcome when used as a source of autologous stem cells for ocular surface regeneration.

Constitutive expression of pentraxin 3 (PTX3) protein by human amniotic membrane cells leads to formation of the heavy chain (HC)-hyaluronan (HA)-PTX3 complex

Heavy chain (HC)-hyaluronan (HA), a complex formed by the covalent linkage between HC1 from the inter-α-trypsin inhibitor (IαI) and HA, purified from the human amniotic membrane (AM), is responsible for the anti-inflammatory, antiscarring, and antiangiogenic actions of the AM. This HC-HA complex is produced by constitutive expression of TNF-stimulated gene 6 and endogenous production of IαI by AM cells. Pentraxin 3 (PTX3), a prototypic long pentraxin that plays a non-redundant role in innate immunity against selected pathogens, also helps stabilize HC-HA to ensure female fertility. Here we noted strong positive PTX3 staining in the AM epithelium and compact stroma. PTX3 was constitutively expressed and secreted by cultured AM epithelial and stromal cells and, further, greatly up-regulated by TNF and IL-1β. Using an agarose overlay to trap the HA-containing matrix, the HC-HA-PTX3 complex was formed, as analyzed by Western blot analysis, by AM cells but not human skin fibroblasts, despite being cultured in the presence of serum and TNF. However, exogenous PTX3 helps human skin fibroblasts form the HC-HA-PTX3 complex with an agarose overlay. Furthermore, PTX3 can be coimmunoprecipitated with the HC-HA complex from agarose-overlaid AM cell extracts by an anti-human IαI antibody. Such a HC-HA-PTX3 complex can be reconstituted in vitro and exhibit similar effects as those reported for AM HC-HA-PTX3 on polarization of M2 macrophages. The tight binding between PTX3 and AM HC-HA withstands four runs of CsCl ultracentrifugation in the presence of 4 m GnHCl. These results indicate that PTX3 is constitutively expressed and secreted by AM cells as an integral component of the AM HC-HA-PTX3 complex and contributes to the biological function of AM HC-HA-PTX3.

In vivo downregulation of innate and adaptive immune responses in corneal allograft rejection by HC-HA/PTX3 complex purified from amniotic membrane

PURPOSE

Heavy chain-hyaluronic acid (HC-HA)/PTX3 purified from human amniotic membrane (AM) was previously observed to suppress inflammatory responses in vitro. We now examine whether HC-HA/PTX3 is able to exert a similar effect in vivo, using murine models for keratitis and corneal allograft rejection.

METHODS

The in vitro effect of HC-HA/PTX3 was tested using OTII ovalbumin (OVA) transgenic, purified CD4(+) T cells, or IFN-γ/lipopolysaccharide (LPS)-stimulated RAW264.7 cells. Cytokine production was measured by ELISA, while cell surface markers and cell proliferation were determined by flow cytometry. In vivo effects of HC-HA/PTX3 were analyzed by quantifying the recruitment of enhanced green fluorescence-labeled macrophages and by measuring the expression of arginase 1 (Arg-1), IL-10, and IL-12 in LPS-induced keratitis in the macrophage Fas-induced apoptosis (Mafia) mouse. The effect of corneal allograft survival in a complete major histocompatibility complex (MHC) mismatched mouse model was assessed by grading corneal opacification.

RESULTS

In vitro studies demonstrated that HC-HA/PTX3 significantly enhanced the expansion of FOXP3 T cells and suppressed cell proliferation and protein expression of IFN-γ, IL-2, CD25, and CD69 in activated CD4(+) T cells. Furthermore, immobilized HC-HA/PTX3 significantly upregulated IL-10 gene expression but downregulated that of IL-12 and IL-23 in activated RAW264.7 cells. Finally, in vivo subconjunctival injection of HC-HA/PTX3 significantly prolonged corneal allograft survival, suppressed macrophage infiltration, and promoted M2 polarization by upregulating Arg-1 and IL-10 but downregulating IL-12.

CONCLUSIONS

HC-HA/PTX3 can suppress inflammatory responses in vivo by modulating both innate and adaptive immunity of macrophages and CD4(+) T cells.

Knockdown of both p120 catenin and Kaiso promotes expansion of human corneal endothelial monolayers via RhoA-ROCK-noncanonical BMP-NFκB pathway

PURPOSE

To determine the signaling pathway involved in expanding contact-inhibited human corneal endothelial cells (HCECs) using p120 and Kaiso small interfering RNAs (siRNAs).

METHODS

Expansion of HCEC monolayers on collagen IV in SHEM using p120 siRNA was optimized regarding various dosage, frequency, and starting date before being added Kaiso siRNA or various inhibitors of Rho, ROCK, NFκB, and TAK1. Phase contrast micrographs were used for monitoring cell shape, monolayer size, and cell density. Immunostaining was used to determine cytolocalization of BrdU, p120, pNFkB, F-actin, α-catenin, β-catenin, LEF1, Na+/K+-ATPase, N-cadherin, ZO-1, and S100A4. Western blotting was used to determine the protein level of RhoA and RhoA-guanosine-5'-triphosphate (GTP).

RESULTS

The HCEC monolayer size in diameter was expanded from 2.1 ± 0.4 mm to 4.3 ± 0.3 mm (P < 0.05) by increasing p120 siRNA from 40 nM to 100 nM starting at day 7, to 5.0 ± 0.4 mm (P < 0.05) by adding 100 nM Kaiso siRNA, to 6.8 ± 0.3 mm by using one-fourth corneoscleral rim (P < 0.05), and to 8.1 ± 0.5 mm by using one-half corneoscleral rim (P < 0.05). Such proliferative effect required activation of RhoA-ROCK-noncanonical bone morphogenic protein (BMP) signaling and nuclear translocation of phosphorylated nuclear factor kappa-light-chain-enhancer of activated B cells (pNFκB). After withdrawal of siRNAs for 1 week, the resultant HCEC monolayer maintained a hexagonal shape, the average cell density of 2254 ± 87 mm(2) (n = 3), and normal expression patterns of F-actin, α-catenin, β-catenin, N-cadherin, ZO-1, and Na+/K+-ATPase without S100A4 and alpha-smooth muscle actin (α-SMA).

CONCLUSIONS

The optimized knockdown with p120 and Kaiso siRNAs further expands the size of HCEC monolayers without endothelial mesenchymal transition (EMT) via selective activation of p120/Kaiso signaling that requires the RhoA-ROCK-noncanonical BMP-NFkB signaling.

Integration of BMP/Wnt signaling to control clonal growth of limbal epithelial progenitor cells by niche cells

Both BMP and Wnt signaling control stem cells in bulge/dermal papilla, intestinal crypt, and bone marrow. To explore their roles in the limbal niche, which govern corneal epithelial homeostasis, we established an in vitro model of sphere growth by reunion between single limbal epithelial progenitor cells (LEPCs) and aggregates of limbal niche cells (LNCs) in 3D Matrigel. Compared to LEPCs alone, spheres formed by LEPC+LNC exhibited higher clonal growth and less corneal epithelial differentiation. Furthermore, pSmad1/5/8 was in the nucleus of LEPCs, but not LNCs, and correlated with upregulation of BMP1, BMP3, BMP4, all three BMP receptors, and BMP target genes. Inactivation of BMP signaling in LNCs was correlated with upregulation of noggin preferentially expressed by LNCs. Additionally, β-catenin was stabilized in the perinuclear cytoplasm in LEPCs and correlated with upregulation of Wnt7A and FZD5 preferentially expressed by LEPCs. Inactivation of Wnt signaling in LNCs was correlated with upregulation of DKK1/2 by LNCs. Addition of XAV939 that expectedly downregulated perinuclear β-catenin in LEPCs led to significant reduction of epithelial clonal growth, but upregulated all three BMP receptors and downregulated LNC-derived noggin, resulting in activation of BMP signaling in LNCs. Addition of noggin that expectedly downregulated nuclear localization of pSmad1/5/8 in LEPCs led to nuclear localization of β-catenin in larger LEPCs but membrane relocation of β-catenin in smaller LEPCs and significant upregulation of DKK1/2. Hence, balancing acts between Wnt signaling and BMP signaling exist not only within LEPCs but also between LEPCs and LNCs to regulate clonal growth of LEPCs.

Terpinen-4-ol is the Most Active Ingredient of Tea Tree Oil to Kill Demodex Mites

PURPOSE

To determine the active ingredient in tea tree oil (TTO) responsible for its reported killing effect on Demodex mites, the most common ectoparasite found in the human skin extending to the eye.

METHODS

Using a reported in vitro killing assay to measure the survival time of adult Demodex folliculorum up to 150 minutes, we have screened serial concentrations of 13 of the 15 known ingredients of TTO (ISO4730:2004) that were soluble in mineral oil and examined their synergistic relationships in killing mites. The most potent ingredient was then tested for its efficacy in killing Demodex in vivo.

RESULTS

All ingredients exhibited a dose-dependent killing effect. Besides Terpinen-4-ol, the order of relative potency did not correlate with the order of relative abundance in TTO for the remaining 12 ingredients. Terpinen-4-ol was the most potent ingredient followed by α-Terpineol, 1,8-Cineole and Sabinene. Terpinen-4-ol, the most abundant ingredient in TTO, was more potent than TTO at equivalent concentrations and its killing effect was even observable at a mere concentration of 1%. Terpinen-4-ol exhibited a significant synergistic effect with Terpinolene, but an antagonistic effect with α-Terpineol in killing mites (both P < 0.05). In vivo, Terpinen-4-ol was shown to eradicate mites.

CONCLUSIONS

The above finding suggests that deployment of Terpinen-4-ol alone should enhance its potency in killing Demodex mites by reducing the adverse and antagonistic effects from other ingredients in TTO.

TRANSLATIONAL RELEVANCE

Terpinen-4-ol can be adopted in future formulations of acaricides to treat a number of ocular and cutaneous diseases caused by demodicosis.

Optimization of Ex Vivo Expansion of Limbal Epithelial Progenitors by Maintaining Native Niche Cells on Denuded Amniotic Membrane

PURPOSE

Transplantation of ex vivo expanded limbal epithelial progenitor cells (LEPCs) on epithelially denuded amniotic membrane (dAM) in supplemented hormonal epithelial medium (SHEM) is an alternative solution for treating corneal blindness due to limbal stem cell (SC) deficiency. Because the phenotype of limbal niche cells (NCs) is preserved better in serum-free modified embryonic stem cell (ESC) medium (MESCM) than SHEM, we question whether the aforementioned expansion protocol can be further optimized by maintaining limbal NCs using MESCM.

METHODS

Collagenase-isolated limbal clusters were cultured on dAM in SHEM or MESCM for 8 to 10 days. Epithelial outgrowth sheets removed by dispase were subjected to real-time quantitative polymerase chain reaction (qPCR) and immunostaining for expression of corneal epithelial markers (p63α, pax6, and K12) and NC markers (FLK-1, CD34, CD31, PDGFR-B, and α-SMA). A total of 1000 single cells were seeded on 6-well dish containing 3T3 feeder layers for 12 to 14 days before rhodamine B staining.

RESULTS

Epithelial outgrowth in SHEM showed a significant loss of corneal SC and ESC markers when compared with freshly collagenase-isolated limbal clusters. Although the epithelial outgrowth was slower in MESCM, epithelial cell size was consistently smaller than that found in SHEM. Furthermore, MESCM maintained a significantly higher percentage of PCK-/ Vim+ cells and exhibited a significant upregulation of NC markers and corneal epithelial SC markers (K15, Bmi-1, and Msi-1) than SHEM. Furthermore, the number of purported holoclones was significantly promoted in MESCM than SHEM.

CONCLUSION

These data collectively suggest that MESCM can be used to replace SHEM to further promote expansion of LEPC by maintaining limbal native NCs.

TRANSLATIONAL RELEVANCE

Effective ex vivo expansion of limbal epithelial SC is a first and important step toward the success of treating corneal blindness caused by limbal stem cell deficiency and paves the way for future applications in regenerative medicine.

Immobilized heavy chain-hyaluronic acid polarizes lipopolysaccharide-activated macrophages toward M2 phenotype

Despite the known anti-inflammatory effect of amniotic membrane, its action mechanism remains largely unknown. HC-HA complex (HC-HA) purified from human amniotic membrane consists of high molecular weight hyaluronic acid (HA) covalently linked to the heavy chain (HC) 1 of inter-α-trypsin inhibitor. In this study, we show that soluble HC-HA also contained pentraxin 3 and induced the apoptosis of both formyl-Met-Leu-Phe or LPS-activated neutrophils and LPS-activated macrophages while not affecting the resting cells. This enhanced apoptosis was caused by the inhibition of cell adhesion, spreading, and proliferation caused by HC-HA binding of LPS-activated macrophages and preventing adhesion to the plastic surface. Preferentially, soluble HC-HA promoted phagocytosis of apoptotic neutrophils in resting macrophages, whereas immobilized HC-HA promoted phagocytosis in LPS-activated macrophages. Upon concomitant LPS stimulation, immobilized HC-HA but not HA polarized macrophages toward the M2 phenotype by down-regulating IRF5 protein and preventing its nuclear localization and by down-regulating IL-12, TNF-α, and NO synthase 2. Additionally, IL-10, TGF-β1, peroxisome proliferator-activated receptor γ, LIGHT (TNF superfamily 14), and sphingosine kinase-1 were up-regulated, and such M2 polarization was dependent on TLR ligation. Collectively, these data suggest that HC-HA is a unique matrix component different from HA and uses multiple mechanisms to suppress M1 while promoting M2 phenotype. This anti-inflammatory action of HC-HA is highly desirable to promote wound healing in diseases heightened by unsuccessful transition from M1 to M2 phenotypes.

Conjunctivochalasis interferes with tear flow from fornix to tear meniscus

PURPOSE

To determine whether conjunctivochalasis (CCh) interferes with tear flow from the fornix to the tear meniscus and depletes the fornix tear reservoir.

DESIGN

Comparative case series.

PARTICIPANTS

The study group of 24 CCh patients (8 asymptomatic and 16 symptomatic), 9 of whom underwent operative correction, was compared with a control group of 13 normal subjects.

METHODS

After instilling a 5-μl fluorescein drop into the inferior fornix, the inferior tear meniscus was depleted using a capillary tube. The tear meniscus height, with and without blinking, was recorded and calculated by video meniscometer from sequential captured images.

MAIN OUTCOME MEASURES

The recovery rate of the original meniscus height was compared among groups at each time point after maximal depletion.

RESULTS

The recovery rate of the tear meniscus was significantly slower in symptomatic than asymptomatic CCh patients when compared with normal subjects. Blinking 5 times facilitated such recovery in normal subjects and in asymptomatic CCh patients to the same extent as the normal, but not in symptomatic CCh patients. Deepening of the inferior fornix by removing degenerated Tenon's and reconstruction by cryopreserved amniotic membrane improved the recovery rate in symptomatic CCh patients to the same extent as normal subjects.

CONCLUSIONS

The tear reservoir in the fornix rapidly replenishes the meniscus under normal circumstances. Conjunctivochalasis obliterates tears not only in the meniscus, but also in the reservoir, explaining how symptoms develop in CCh patients. Blinking is an effective compensatory mechanism to distinguish the severity of CCh. Surgical correction should not only restore the tear meniscus, but also deepen the fornix in CCh patients.

FINANCIAL DISCLOSURE(S)

Proprietary or commercial disclosure may be found after the references.

Activation of Smad-mediated TGF-β signaling triggers epithelial-mesenchymal transitions in murine cloned corneal progenitor cells

Epithelial-mesenchymal transition (EMT), via activation of Wnt signaling, is prevailing in embryogenesis, but postnatally it only occurs in pathological processes, such as in tissue fibrosis and tumor metastasis. Our prior studies led us to speculate that EMT might be involved in the loss of limbal epithelial stem cells in explant cultures. To examine this hypothesis, we successfully grew murine corneal/limbal epithelial progenitors by prolonging the culture time and by seeding at a low density in a serum-free medium. Single cell-derived clonal growth was accompanied by a gradient of Wnt signaling activity, from the center to the periphery, marked by a centrifugal loss of E-cadherin and β-catenin from intercellular junctions, coupled with nuclear translocation of β-catenin and LEF-1. Large-colony-forming efficiency at central location of colony was higher than peripheral location. Importantly, there was also progressive centrifugal differentiation, with positive K14 keratin expression and the loss of p63 and PCNA nuclear staining, and irreversible EMT, evidenced by cytoplasmic expression of α-SMA and nuclear localization of S100A4; and by nuclear translocation of Smad4. Furthermore, cytoplasmic expression of α-SMA was promoted by high-density cultures and their conditioned media, which contained cell density-dependent levels of TGF-β1, TGF-β2, GM-CSF, and IL-1α. Exogenous TGF-β1 induced α-SMA positive cells in a low-density culture, while TGF-β1 neutralizing antibody partially inhibited α-SMA expression in a high-density culture. Collectively, these results indicate that irreversible EMT emerges in the periphery of clonal expansion where differentiation and senescence of murine corneal/limbal epithelial progenitors occurs as a result of Smad-mediated TGF-β-signaling.

Mesenchymal stem cells derived from human limbal niche cells

PURPOSE

We investigated whether human limbal niche cells generate mesenchymal stem cells.

METHODS

Limbal niche cells were isolated from the limbal stroma by collagenase alone or following dispase removal of the limbal epithelium (D/C), and cultured on plastic in Dulbecco's modified Eagle's medium (DMEM) with 10% fetal bovine serum (FBS), or coated or three-dimensional Matrigel in embryonic stem cell medium with leukemia inhibitory factor and basic fibroblast growth factor. Expression of cell markers, colony-forming units-fibroblast, tri-lineage differentiation, and ability of supporting limbal epithelial stem/progenitor cells were compared to limbal residual stromal cells.

RESULTS

Stromal cells expressing angiogenesis markers were found perivascularly, subjacent to limbal basal epithelial cells, and in D/C and limbal residual stromal cells. When seeded in three-dimensional Matrigel, D/C but not limbal residual stromal cells yielded spheres of angiogenesis progenitors that stabilized vascular networks. Similar to collagenase-isolated cells, D/C cells could be expanded on coated Matrigel for more than 12 passages, yielding spindle cells expressing angiogenesis and mesenchymal stem cells markers, and possessing significantly higher colony-forming units-fibroblast and more efficient tri-lineage differentiation than D/C and limbal residual stromal cells expanded on plastic in DMEM with 10% FBS, of which both lost the pericyte phenotype while limbal residual stromal cells turned into myofibroblasts. Upon reunion with limbal epithelial stem/progenitor cells to form spheres, D/C cells expanded on coated Matrigel maintained higher expression of p63α and lower expression of cytokeratin 12 than those expanded on plastic in DMEM with 10% FBS, while spheres formed with human corneal fibroblasts expressed cytokeratin 12 without p63α.

CONCLUSIONS

In the limbal stroma, cells subjacent to limbal basal epithelial cells serve as niche cells, and generate progenitors with angiogenesis and mesenchymal stem cells potentials. They might partake in angiogenesis and regeneration during corneal wound healing.

PTX3 controls activation of matrix metalloproteinase 1 and apoptosis in conjunctivochalasis fibroblasts

PURPOSE

Conjunctivochalasis (CCh) is an age-related inflammatory ocular surface disease manifesting redundant, loose conjunctiva folds. The pathogenic role of Pentraxin 3 (PTX3) in controlling upregulation of matrix metalloproteinase 1 (MMP-1) and MMP-3 in CCh remains undefined.

METHODS

Cytolocation of PTX3 and apoptosis were compared by immunostaining and terminal deoxyribonucleotidyl transferase-mediated FITC-linked dUTP nick-end DNA labeling (TUNEL) assay between normal and CCh specimens containing the conjunctiva and the Tenon. Second to third cultures of normal and CCh fibroblasts were treated with or without Aprotinin, Batimastat, or N-isobutyl-N-(4-methoxyphenylsulfonyl)-glycylhydroxamic acid (NNGH), followed by transfection with or without PTX3 siRNA, and TNF-α or IL-1β. Cell lysates and culture media were collected to assess apoptosis measured by the Cell Death Detection ELISA and expression of PTX3, MMP-1, and MMP-3 transcripts and proteins by quantitative RT-PCR and Western blot, respectively.

RESULTS

PTX3 immunostaining was negative in normal specimens, but strongly positive in the subconjunctival stroma of CCh specimens. More apoptotic cells were found in CCh samples than in normal specimens. Expression of PTX3 transcripts and protein was not constitutive in resting normal fibroblasts but was in resting CCh fibroblasts and was upregulated by IL-1β in both cell lysates and culture media of both fibroblasts. PTX3 siRNA further upregulated MMP-1 and MMP-3 transcripts in resting normal fibroblasts, but synergistically with IL-1β upregulated the expression of MMP-1 and MMP-3 transcripts only in CCh fibroblasts, with activation of MMP-1 more so than MMP-3. PTX3 siRNA knockdown also promoted cell death characterized by apoptosis and necrosis, and such cell death could be rescued by inhibitors against serine proteinase, MMP1, or MMP3.

CONCLUSIONS

Perturbation of PTX3 expression might partake in apoptosis and pathogenesis of CCh by upregulating expression of MMP-1 and MMP-3, and activation of MMP-1 and MMP-3.

Angiogenesis potential of human limbal stromal niche cells

PURPOSE

The perivascular localization of stem cell (SC) niches suggests the presence of a vascular niche. We aimed to determine the angiogenesis potential of limbal niche cells (NCs).

METHODS

Human limbal NCs were isolated and serially passaged on plastic or coated Matrigel in embryonic SC medium containing BFGF and leukemia inhibitory factor before being reseeded in 3D Matrigel. Expression of angiogenesis markers was assessed by RT-qPCR and immunofluorescence staining. Their angiogenesis potential was measured by differentiation into vascular endothelial cells and by supporting vascular tube network formed by human umbilical vein endothelial cells (HUVEC) on Matrigel. Their support of limbal epithelial progenitor cells (LEPC) was examined in sphere growth formed by reunion in 3D Matrigel.

RESULTS

On plastic, limbal NC could be cultured only up to four passages before turning into myofibroblasts. In contrast, on coated Matrigel, they could be expanded for up to 12 passages with upregulation of markers suggestive of angiogenesis progenitors when reseeded in 3D Matrigel because they could differentiate into vascular endothelial cells and pericytes stabilizing the tube network formed by HUVEC. Although both expanded limbal NCs and HUVEC rejoined with LEPC to form spheres to upregulate expression of ΔNp63α, CK15, and CEBPδ, the former but not the latter abolished expression of CK12 keratin.

CONCLUSIONS

Human limbal NCs continuously expanded on the basement membrane differentiate into angiogenesis progenitors that prevent differentiation of LEPC/SCs. They may partake in formation of the vascular niche and contribute to angiogenesis during wound healing.