Enhanced survival in vitro of human corneal endothelial cells using mouse embryonic stem cell conditioned medium

Effect of Rho-Associated Kinase Inhibitor and Mesenchymal Stem Cell-Derived Conditioned Medium on Corneal Endothelial Cell Senescence and Proliferation

This study aims to obtain sufficient corneal endothelial cells for regenerative application. We examined the combinatory effects of Rho-associated kinase (ROCK) inhibitor Y-27632 and mesenchymal stem cell-derived conditioned medium (MSC-CM) on the proliferation and senescence of rabbit corneal endothelial cells (rCECs). rCECs were cultured in a control medium, a control medium mixed with either Y-27632 or MSC-CM, and a combinatory medium containing Y-27632 and MSC-CM. Cells were analyzed for morphology, cell size, nuclei/cytoplasmic ratio, proliferation capacity and gene expression. rCECs cultured in a combinatory culture medium showed a higher passage number, cell proliferation, and low senescence. rCECs on collagen type I film showed high expression of tight junction. The cell proliferation marker Ki-67 was positively stained either in Y-27632 or MSC-CM-containing media. Genes related to cell proliferation resulted in negligible changes in MKI67, CIP2A, and PCNA in the combinatory medium, suggesting proliferative capacity was maintained. In contrast, all of these genes were significantly downregulated in the other groups. Senescence marker β-galactosidase-positive cells significantly decreased in either MSC-CM and/or Y-27632 mixed media. Senescence-related genes downregulated LMNB1 and MAP2K6, and upregulated MMP2. Cell cycle checkpoint genes such as CDC25C, CDCA2, and CIP2A did not vary in the combinatory medium but were significantly downregulated in either ROCK inhibitor or MSC-CM alone. These results imply the synergistic effect of combinatory culture medium on corneal endothelial cell proliferation and high cell number. This study supports high potential for translation to the development of human corneal endothelial tissue regeneration.

Translational and Regulatory Challenges of Corneal Endothelial Cell Therapy: A Global Perspective

Cell therapies are emerging as a unique class of clinical therapeutics in medicine. In 2015, Holoclar (ex vivo expanded autologous human corneal epithelial cells containing stem cells) gained the regulatory approval for treating limbal stem cell deficiency after chemical eye burn. This has set a precedent in ophthalmology and in medicine, reinforcing the therapeutic promise of cell therapy. However, to generalize and commercialize cell therapies on a global scale, stringent translational and regulatory requirements need to be fulfilled at both local and international levels. Over the past decade, the Singapore group has taken significant steps in developing human corneal endothelial cell (HCEnC) therapy for treating corneal endothelial diseases, which are currently the leading indication for corneal transplantation in many countries. Successful development of HCEnC therapy may serve as a novel solution to the current global shortage of donor corneas. Based on the experience in Singapore, this review aims to provide a global perspective on the translational and regulatory challenges for bench-to-bedside translation of cell therapy. Specifically, we discussed about the characterization of the critical quality attributes (CQA), the challenges that can affect the CQA, and the variations in the regulatory framework embedded within different regions, including Singapore, Europe, and the United States. Impact statement Functional corneal endothelium is critical to normal vision. Corneal endothelial disease-secondary to trauma, surgery, or pathology-represents an important cause of visual impairment and blindness in both developed and developing countries. Currently, corneal transplantation serves as the current gold standard for treating visually significant corneal endothelial diseases, although limited by the shortage of donor corneas. Over the past decade, human corneal endothelial cell therapy has emerged as a promising treatment option for treating corneal endothelial diseases. To allow widespread application of this therapy, significant regulatory challenges will need to be systematically overcome.

Reversed Senescence of Retinal Pigment Epithelial Cell by Coculture With Embryonic Stem Cell via the TGFβ and PI3K Pathways

Retinal pigment epithelium (RPE) cellular senescence is an important etiology of age-related macular degeneration (AMD). Aging interventions based on the application of stem cells to delay cellular senescence have shown good prospects in the treatment of age-related diseases. This study aimed to investigate the potential of the embryonic stem cells (ESCs) to reverse the senescence of RPE cells and to elucidate its regulatory mechanism. The hydrogen peroxide (H₂O₂)-mediated premature and natural passage-mediated replicative senescent RPE cells were directly cocultured with ESCs. The results showed that the proliferative capacity of premature and replicative senescent RPE cells was increased, while the positive rate of senescence-associated galactosidase (SA-β-GAL) staining and levels of reactive oxygen species (ROS) and mitochondrial membrane potential (MMP) were decreased. The positive regulatory factors of cellular senescence (p53, p21^WAF1/CIP1, p16^INK4a) were downregulated, while the negative regulatory factors of cellular senescence (Cyclin A2, Cyclin B1, Cyclin D1) were upregulated. Furthermore, replicative senescent RPE cells entered the S and G₂/M phases from the G₀/G₁ phase. TGFβ (TGFB1, SMAD3, ID1, ID3) and PI3K (PIK3CG, PDK1, PLK1) pathway-related genes were upregulated in premature and replicative senescent RPE cells after ESCs application, respectively. We further treated ESCs-cocultured premature and replicative senescent RPE cells with SB531542 and LY294002 to inhibit the TGFβ and PI3K pathways, respectively, and found that p53, p21^WAF1/CIP1 and p16^INK4a were upregulated, while Cyclin A2, Cyclin B1, Cyclin D1, TGFβ, and PI3K pathway-related genes were downregulated, accompanied by decreased proliferation and cell cycle transition and increased positive rates of SA-β-GAL staining and levels of ROS and MMP. In conclusion, we demonstrated that ESCs can effectively reverse the senescence of premature and replicative senescent RPE cells by a direct coculture way, which may be achieved by upregulating the TGFβ and PI3K pathways, respectively, providing a basis for establishing a new therapeutic option for AMD.

Embryonic stem cell microenvironment enhances proliferation of human retinal pigment epithelium cells by activating the PI3K signaling pathway

BACKGROUND

Retinal pigment epithelium (RPE) replacement has been proposed as an efficacious treatment for age-related macular degeneration (AMD), which is the primary cause of vision loss in the elderly worldwide. The embryonic stem cell (ESC) microenvironment has been demonstrated to enable mature cells to gain a powerful proliferative ability and even enhance the stem/progenitor phenotype via activation of the phosphoinositide 3-kinase (PI3K) signaling pathway. As the PI3K signaling pathway plays a pivotal role in proliferation and homeostasis of RPE, we hypothesize that the stemness and proliferative capability of RPE can be enhanced by the ESC microenvironment via activation of the PI3K signaling pathway.

METHODS

To investigate whether the ESC microenvironment improves the stem cell phenotype and proliferation properties of human RPE (hRPE) cells by regulating the PI3K signaling pathway, primary hRPE cells were cocultured with either ESCs or human corneal epithelial cells (CECs) for 72 h, after which their proliferation, apoptosis, cell cycle progression, and colony formation were assayed to evaluate changes in their biological characteristics. Gene expression was detected by real-time PCR and protein levels were determined by western blotting or immunofluorescence. LY294002, an antagonist of the PI3K signaling pathway, was used to further confirm the mechanism involved.

RESULTS

In comparison to hRPE cells cultured alone, hRPE cells cocultured with ESCs had an increased proliferative capacity, reduced apoptotic rate, and higher colony-forming efficiency. The expression of the stem cell-associated marker KLF4 and the differentiation marker CRALBP increased and decreased, respectively, in hRPE cells isolated from the ESC coculture. Furthermore, PI3K pathway-related genes were significantly upregulated in hRPE cells after exposure to ESCs. LY294002 reversed the pro-proliferative effect of ESCs on hRPE cells. In contrast, CECs did not share the ability of ESCs to influence the biological behavior and gene expression of hRPE cells.

CONCLUSIONS

Our findings indicate that the ESC microenvironment enhances stemness and proliferation of hRPE cells, partially via activation of the PI3K signaling pathway. This study may have a significant impact and clinical implication on cell therapy in regenerative medicine, specifically for age-related macular degeneration.

Exploring the Mesenchymal Stem Cell Secretome for Corneal Endothelial Proliferation

Ex vivo grown human corneal endothelial cells (HCEnC) are a new emerging treatment option to treat visually impaired patients aimed at alleviating the current global donor shortage. Expanding HCEnC is still challenging, and obtaining cells in sufficient quantities is a limiting factor. It is already known that conditioned medium obtained from bone marrow mesenchymal stem cells can stimulate the proliferation of endothelial cells. The aim of this study was to take this work a step further to identify some of the underlying factors responsible. We confirmed the stimulatory effect of the mesenchymal stem cell secretome seen previously and separated the exosomes from the soluble proteins using size exclusion chromatography. We demonstrated the presence of exosomes and soluble proteins in the early and late fractions, respectively, with transmission electron microscopy and protein assays. Proliferation studies demonstrated that growth stimulation could be reproduced with the later protein-rich fractions but not with the exosome-rich fraction. Antibody assays revealed the presence of the secreted proteins EGF, IGFBP2, and IGFBP6 in protein-high fractions, but the growth enhancement was not seen with purified protein formulations. In conclusion, we confirmed the stimulatory effect of stem cell-conditioned medium and have determined that the effect was attributable to the proteins rather than to the exosomes. We were not able to reproduce the growth stimulation, however, with the pure recombinant protein candidates tested. Specific identification of the underlying proteins using proteomics could render a bioactive protein that can be used for ex vivo expansion of cells or as an in vivo drug to treat early corneal endothelial damage.

Embryonic stem cell microenvironment suppresses the malignancy of cutaneous melanoma cells by down-regulating PI3K/AKT pathway

Malignant cancer cells engage in a dynamic reciprocity with the tumor microenvironment (TME) that promotes tumor growth, development, and resistance to therapy. Early embryonic blastocyst microenvironments can reverse the tumorigenic phenotype of malignant cancer cells via ameliorating of TME. It is potential to apply embryonic stem cell (ESC) microenvironment to suppress the malignant behaviors of cancer cells. This study aimed to investigate a better method and the mechanism of ESC microenvironment supplied by ESCs on suppressing the malignancy of cutaneous melanoma cells. Cutaneous melanoma cell line A2058 were cultured and divided into four groups: (a) A2058-only (Control); (b) A2058 and ESCs continuously co-cultured (Group One); (c) A2058 co-cultured with daily refreshed ESCs (Group two); (d) Group one with VO-Ohpic, inhibitor of PTEN (VO-Ohpic Group). The results showed that, compared to control group, A2058 cells in group one exhibited decreased cellular proliferation, migration, invasiveness and vasculogenic mimicry concomitant with an increase in cell apoptosis, accompanied by down-regulation of PI3K/AKT pathway. Besides, the above mentioned anti-tumor effects on A2058 cells were significantly enhanced in group two but statistically weakened after administration of VO-Ohpic compared to group one. We demonstrate that ESC microenvironment reduces the malignancy of A2058 by down-regulating PI3K/AKT pathway. Notably, such anti-tumor effects can be enhanced by appropriately increasing the quality and quantity of ESCs in co-culture system. Our results suggest that ESC microenvironment could be an effective and safe approach to treating cancer.

Characterization of the iPSC-derived conditioned medium that promotes the growth of bovine corneal endothelial cells

Corneal endothelial cells (CECs) maintain corneal transparency and visual acuity. However, the limited proliferative capability of these cells in vitro has prompted researchers to find efficient culturing techniques for them. The aim of our study was to evaluate the use of conditioned medium (CM) obtained from induced pluripotent stem cells (iPSCs) as a source for the effective proliferation of bovine CECs (B-CECs). In our study, the proliferative ability of B-CECs was moderately enhanced when the cells were grown in 25% iPSC conditioned medium (iPSC-CM). Additionally, hexagonal cell morphology was maintained until passage 4, as opposed to the irregular and enlarged shape observed in control corneal endothelial medium (CEM). B-CECs in both the 25% iPSC-CM and CEM groups expressed and Na+-K+-ATPase. The gene expression levels of NIFK, Na+-K+-ATPase, Col4A and Col8A and the percentage of cells entering S and G2 phases were higher in the iPSC-CM group. The number of apoptotic cells also decreased in the iPSC-CM group. In comparison to the control cultures, iPSC-CM facilitated cell migration, and these cells showed better barrier functions after several passages. The mechanism of cell proliferation mediated by iPSC-CM was also investigated, and phosphorylation of Akt was observed in B-CECs after exposure to iPSC-CM and showed sustained phosphorylation induced for up to 180 min in iPSC-CM. Our findings indicate that iPSC-CM may employ PI3-kinase signaling in regulating cell cycle progression, which can lead to enhanced cellular proliferation. Effective component analysis of the CM showed that in the iPSC-CM group, the expression of activin-A was significantly increased. If activin-A is added as a supplement, it could help to maintain the morphology of the cells, similar to that of CM. Hence, we conclude that activin-A is one of the effective components of CM in promoting cell proliferation and maintaining cell morphology.

Therapy of corneal endothelial dysfunction with corneal endothelial cell-like cells derived from skin-derived precursors

Corneal endothelial dysfunction occurs when corneal endothelial cells (CECs) are dramatically lost and eventually results in vision loss. Corneal transplantation is the only solution at present. However, corneal transplantation requires a fresh human cornea and there is a worldwide shortage of donors. Therefore, finding new functional CECs to replace human CECs is urgent. Skin-derived precursors (SKPs) can be easily acquired and have multiple differential potential. We co-cultured human SKPs with B4G12 cells in serum-free medium and obtained abundant CEC-like cells which had similar morphology and characteristic to human CECs. CEC-like cells exerted excellent therapeutic effect when they were transplanted into rabbit and monkey corneal endothelial dysfunction models by injection method. This protocol enables efficient production of CEC-like cells from SKPs. The renewable cell source, novel derivation method and simple treatment strategy may lead to potential applications in cell replacement therapy for corneal endothelial dysfunction.

Transcriptomic Analysis of Cultured Corneal Endothelial Cells as a Validation for Their Use in Cell Replacement Therapy

The corneal endothelium plays a primary role in maintaining corneal homeostasis and clarity and must be surgically replaced with allogenic donor corneal endothelium in the event of visually significant dysfunction. However, a worldwide shortage of donor corneal tissue has led to a search for alternative sources of transplantable tissue. Cultured human corneal endothelial cells (HCEnC) have been shown to restore corneal clarity in experimental models of corneal endothelial dysfunction in animal models, but characterization of cultured HCEnC remains incomplete. To this end, we utilized next-generation RNA sequencing technology to compare the transcriptomic profile of ex vivo human corneal endothelial cells (evHCEnC) with that of primary HCEnC (pHCEnC) and HCEnC lines and to determine the utility of cultured and immortalized corneal endothelial cells as models of in vivo corneal endothelium. Multidimensional analyses of the transcriptome data sets demonstrated that primary HCEnC have a closer relationship to evHCEnC than do immortalized HCEnC. Subsequent analyses showed that the majority of the genes specifically expressed in HCEnC (not expressed in ex vivo corneal epithelium or fibroblasts) demonstrated a marked variability of expression in cultured cells compared with evHCEnC. In addition, genes associated with either corneal endothelial cell function or corneal endothelial dystrophies were investigated. Significant differences in gene expression and protein levels were observed in the cultured cells compared with evHCEnC for each of the genes tested except for AGBL1 and LOXHD1, which were not detected by RNA-seq or qPCR. Our transcriptomic analysis suggests that at a molecular level pHCEnC most closely resemble evHCEnC and thus represent the most viable cell culture-based therapeutic option for managing corneal endothelial cell dysfunction. Our findings also suggest that investigators should perform an assessment of the entire transcriptome of cultured HCEnC prior to determination of their potential clinical utility for the management of corneal endothelial cell failure.

Identification and potential application of human corneal endothelial progenitor cells

The corneal endothelium is believed to be developmentally originated from the periocular mesenchyme via the neural crest. Human corneal endothelial progenitor cells (HCEPs) have been investigated because of their potential availability for the tissue regenerative medicine. However, the existence and the properties of HCEPs have not been elucidated yet. We first established a novel serum-free culture system for HCEPs. The HCEPs highly expressed p75 neurotrophin receptor, SOX9, and FOXC2, and partially retained the properties of neural crest and periocular mesenchyme. Further, we demonstrated that HCEPs had a high proliferative potency, and the differentiated HCEP sheets had corneal endothelial function by using the Ussing chamber system and transplantation to the rabbit cornea. These findings suggest that the HCEPs can be selectively expanded from the corneal endothelium using a specific culture system and will provide cell sheets for corneal regenerative medicine.

Corneal endothelial expansion promoted by human bone marrow mesenchymal stem cell-derived conditioned medium

Healthy corneal endothelium is essential for maintaining corneal clarity, as the damage of corneal endothelial cells and loss of cell count causes severe visual impairment. Corneal transplantation is currently the only therapy for severe corneal disorders. The greatly limited proliferative ability of human corneal endothelial cells (HCECs), even in vitro, has challenged researchers to establish efficient techniques for the cultivating HCECs, a pivotal issue for clinical applications. The aim of this study was to evaluate conditioned medium (CM) obtained from human bone marrow-derived mesenchymal stem cells (MSCs) (MSC-CM) for use as a consistent expansion protocol of HCECs. When HCECs were maintained in the presence of MSC-CM, cell morphology assumed a hexagonal shape similar to corneal endothelial cells in vivo, as opposed to the irregular cell shape observed in control cultures in the absence of MSC-CM. They also maintained the functional protein phenotypes; ZO-1 and Na(+)/K(+)-ATPase were localized at the intercellular adherent junctions and pump proteins of corneal endothelium were accordingly expressed. In comparison to the proliferative potential observed in the control cultures, HCECs maintained in MSC-CM were found to have more than twice as many Ki67-positive cells and a greatly increased incorporation of BrdU into DNA. MSC-CM further facilitated the cell migration of HCECs. Lastly, the mechanism of cell proliferation mediated by MSC-CM was investigated, and phosphorylation of Akt and ERK1/2 was observed in HCECs after exposure to MSC-CM. The inhibitor to PI 3-kinase maintained the level of p27(Kip1) for up to 24 hours and greatly blocked the expression of cyclin D1 and D3 during the early G1 phase, leading to the reduction of cell density. These findings indicate that MSC-CM not only stimulates the proliferation of HCECs by regulating the G1 proteins of the cell cycle but also maintains the characteristic differentiated phenotypes necessary for the endothelial functions.

ES micro-environment enhances stemness and inhibits apoptosis in human limbal stem cells via the maintenance of telomerase activity

Our previous work had found that telomerase rejuvenated in the cytoplasm of corneal epithelial cells cultured in embryonic stem cell-conditioned medium, the functional properties of stem-like corneal epithelial cells can be enhanced by co-culturing with embryonic stem cells (ESCs) via activation of the integrinβ1-FAK-PI3K/Akt signaling pathway. The goal of this study was to explore the potential molecular mechanisms of the ES micro-environment that enhance the stem cell-like phenotype and inhibit apoptosis in human limbal stem cells (LSC). The LSC were cultured in different media, either CnT-20 medium or CnT-20 +20% ES culture supernatant (ESC-CM). We observed that LSC cultured in ESC-CM had an increased proliferative capacity, greater serial passage capacity, higher colony-forming efficiency (CFE) and higher levels of stem cell-associated marker than those cultured in CnT-20. Compared with CnT-20, ESC-CM enhanced the undifferentiated status and inhibited apoptosis in the LSC by promoting the maintenance of telomerase activity, which could reduce the generation of reactive oxygen species (ROS), maintain the membrane potential (Δψm) at higher levels and reduce the expression of the p21 protein. Our findings indicated that ESC-CM system induced LSC to maintain a stem cell phenotype and inhibit the process of apoptosis. These effects might partially be achieved via the telomerase-p21-mitochondrial axis and the activation of the FAK/Wnt signaling pathways. This study may have high impact and clinic implication on the expansion of LSC in regenerative medicine, especially for ocular surface reconstruction.

Indirect co-culture with tendons or tenocytes can program amniotic epithelial cells towards stepwise tenogenic differentiation

BACKGROUND

Amniotic epithelial cells (AEC) have potential applications in cell-based therapy. Thus far their ability to differentiate into tenocytes has not been investigated although a cell source providing a large supply of tenocytes remains a priority target of regenerative medicine in order to respond to the poor self-repair capability of adult tendons. Starting from this premise, the present research has been designed firstly to verify whether the co-culture with adult primary tenocytes could be exploited in order to induce tenogenic differentiation in AEC, as previously demonstrated in mesenchymal stem cells. Since the co-culture systems inducing cell differentiation takes advantage of specific soluble paracrine factors released by tenocytes, the research has been then addressed to study whether the co-culture could be improved by making use of the different cell populations present within tendon explants or of the high regenerative properties of fetal derived cell/tissue.

METHODOLOGY/PRINCIPAL FINDINGS

Freshly isolated AEC, obtained from ovine fetuses at mid-gestation, were co-incubated with explanted tendons or primary tenocytes obtained from fetal or adult calcaneal tendons. The morphological and functional analysis indicated that AEC possessed tenogenic differentiation potential. However, only AEC exposed to fetal-derived cell/tissues developed in vitro tendon-like three dimensional structures with an expression profile of matrix (COL1 and THSB4) and mesenchymal/tendon related genes (TNM, OCN and SCXB) similar to that recorded in native ovine tendons. The tendon-like structures displayed high levels of organization as documented by the cell morphology, the newly deposited matrix enriched in COL1 and widespread expression of gap junction proteins (Connexin 32 and 43).

CONCLUSIONS/SIGNIFICANCE

The co-culture system improves its efficiency in promoting AEC differentiation by exploiting the inductive tenogenic soluble factors released by fetal tendon cells or explants. The co-cultural system can be proposed as a low cost and easy technique to engineer tendon for biological study and cell therapy approach.

Cornea lenticule viability and structural integrity after refractive lenticule extraction (ReLEx) and cryopreservation

PURPOSE

To assess and compare keratocyte viability and collagen structure in cornea stroma lenticules collected immediately after refractive lenticule extraction (ReLEx) and one month after cryopreservation.

METHODS

The fresh and cryopreserved human stroma lenticules procured after ReLEx were processed for ultrastructural analysis of keratocytes and collagen fibrils with transmission electron microscopy (TEM), apoptotic cell detection with deoxynucleotidyl transferase-mediated nick end labeling assay (TUNEL) assay, and cultured for keratocyte-specific gene expression analysis using reverse transcriptase polymerase chain reaction (RT-PCR).

RESULTS

The periphery of the lenticule had greater TUNEL-positive cells compared to the center of the lenticule in both fresh and cryopreserved groups. There was an increase in TUNEL-positive cells after cryopreservation, which was significantly higher in the center of the lenticule, but not in the periphery. TEM showed apoptotic, necrotic and viable quiescent keratocytes in fresh and cryopreserved lenticules. Collagen analysis with TEM showed a well preserved and well aligned structure in fresh and cryopreserved lenticules; without significant change in the total number of collagen fibrils but with an increased collagen fibril density (CFD) after cryopreservation. In vitro, isolated keratocytes derived from fresh and cryopreserved lenticules exhibited a typical fibroblastic phenotype. RT-PCR showed a positive gene expression for keratocan (KERA) and aldehyde dehydrogenase 3A1 (ALDH3A1) in cells isolated from fresh and cryopreserved lenticules.

CONCLUSIONS

The stromal lenticules extracted from ReLEx surgery remain viable after cryopreservation. Although they showed a decrease in CFD, the collagen architecture was preserved and there was good cellular viability.

Aspirin-triggered lipoxin A4 (15-epi-LXA4) increases the endothelial viability of human corneas storage in Optisol-GS

PURPOSE

The human corneal endothelium has a very low mitotic rate, and with aging there is a decrease in the number of cells. 15-epi-LXA4 is an anti-inflammatory, bioactive lipid formed when aspirin acetylates cyclooxygenease-2 and redirects cyclooxygenease-2 catalytic activity away from prostaglandins. The purpose of the current study was to evaluate the action of 15-epi-LXA4 in the endothelium viability of human corneas stored in Optisol-GS.

METHODS

Human corneal endothelial (HCE) cells along with the Descemet's membrane were isolated from fresh human eyes obtained from National Disease Research Interchange. Cell phenotype was identified by using the tight junctions cell marker ZO-1. LXA4 receptor (FPR2/ALX) was detected by immunostaining of HCE cells and human corneal tissue using a polyclonal antibody. Cell proliferation was evaluated with Ki-67 antibody. To measure cell migration, confluent HCE cells were wounded by a linear scraping with a sterile pipette tip in the center of the well and incubated for 24 h with or without 15-epi-LXA4. To evaluate the reparative capacity of 15-epi-LXA4, 7 pairs of human corneas were incubated in Dulbecco's modified Eagle's medium/F12 media at 37°C with or without 100 nM 15-epi-LXA4 for 24 h and then stored at 4°C in Optisol-GS for 12 days. Endothelial viability was assessed by 2 staining techniques: a viability/cytotoxicity kit and trypan blue combined with alizarin red S.

RESULTS

HCE cells and the endothelium of human corneal sections strongly expressed the LXA4 receptor. There was a 3-fold increase in cell proliferation when HCE cells were incubated with 100 nM 15-epi-LXA4 for 24 h. No significant migration was observed after 24 h incubation with 15-epi-LXA4. Corneas incubated for 24 h in Dulbecco's modified Eagle's medium/F12 media in the presence of 15-epi-LXA4 and then stored for 12 days in Optisol-GS had a 36% to 56% increase in viability compared with controls without 15-epi-LXA4.

CONCLUSIONS

15-epi-LXA4 is an important mediator that protects the integrity of the human endothelium during corneal preservation in Optisol-GS.

Rapidly constructed scaffold-free cornea epithelial sheets for ocular surface reconstruction

PURPOSE

To develop a centrifugal cell seeding method for rapid and efficient reconstruction of ocular surface with limbal stem cell deficiency (LSCD) in rabbits.

METHODS

The orthogonal design method was used to optimize centrifugation parameters for cell seeding. Methylthiazol tetrazolium proliferation assay, colony-forming efficiency, and flow cytometry were used to study cell viability. Histology, electron microscopy, and immunocytochemistry were evaluated for centrifugation-constructed cornea epithelial sheets (CCCESs). The rabbit eyes with LSCD were treated with or without CCCES for in vivo evaluation.

RESULTS

The 80.04% attached cells with 98.04% viability were achieved using optimal cell seeding density at 9 × 10(5) cm(-2) with centrifugation at 1800 rpm for 4 min. The 0.4% glycerin was added in the medium to increase the surface tension and osmotic pressure to optimal condition for obtaining higher cell density. The three-layer epithelial sheets were rapid constructed, which displayed the characteristics of normal corneal epithelium. In vivo transplantation, labeled cells of CCCES were detected at 30 days. CCCES reconstructed the LSCD corneal epithelia without conjunctivalization and neovascularation, evidenced by positive K3 and negative K4, Muc5AC.

CONCLUSION

The scaffold-free corneal epithelial sheets were rapidly constructed using optimal centrifugation procedure, which was demonstrated to reconstruct ocular surface with LSCD.