Serum-free cultivation of bovine lens epithelial cells

Methodologies to unlock the molecular expression and cellular structure of ocular lens epithelial cells

The transparent ocular lens in the anterior chamber of the eye is responsible for fine focusing of light onto the retina. The lens is entirely cellular with bulk of the tissue composed of fiber cells, and the anterior hemisphere of the lens is covered by a monolayer of epithelial cells. Lens epithelial cells are important for maintaining fiber cell homeostasis and for continual growth of the lens tissue throughout life. Cataracts, defined as any opacity in the lens, remain the leading cause of blindness in the world. Following cataract surgery, lens epithelial cells can undergo a process of epithelial-to-mesenchymal transition (EMT), leading to secondary cataracts due to posterior capsular opacification (PCO). Since the epithelial cells make up only a small fraction of the lens, specialized techniques are required to study lens epithelial cell biology and pathology. Studies using native lens epithelial cells often require pooling of samples to obtain enough cells to make sufficient samples for traditional molecular biology techniques. Here, we provide detailed protocols that enable the study of native mouse lens epithelial cells, including immunostaining of the native lens epithelium in flat mounts, extraction of RNA and proteins from pairs of lens epithelial monolayers, and isolation of lens epithelial cells for primary culture. These protocols will enable researchers to gain better insight on representative molecular expression and cellular structure of lens epithelial cells. We also provide comparative data between native, primary culture, and immortalized lens epithelial cells and discuss the advantages and disadvantages of each technique presented.

Distinct Anti-Fibrotic Effects of Exosomes Derived from Endothelial Colony-Forming Cells Cultured Under Normoxia and Hypoxia

Background

The therapeutic potential of endothelial colony-forming cells (ECFCs) may be impaired in an ischemic environment. Direct injection of ECFCs is not an effective method of rescuing the ischemic heart, but exosomes derived from these cells may be a promising therapeutic tool. However, exosomes produced under normoxia and hypoxia may not be identical. Therefore, the purpose of this study was to investigate alterations in the anti-fibrotic effects of hypoxia-treated ECFC-derived exosomes and the underlying mechanism involved.

Material/Methods

ECFCs were isolated from peripheral blood and exosomes were collected from ECFCs treated with normoxia (nor-exo) or hypoxia (hyp-exo). Effects of exosomes on cardiac fibroblast activation were evaluated in vitro. MicroRNAs (miRNAs) inside the exosomes were extracted and compared using next-generation RNA sequencing. Predicted target mRNAs of miR-10b-5p were validated using a dual-luciferase reporter gene assay method.

Results

Nor-exo significantly ameliorated cardiac fibroblast activation in vitro. These effects were attenuated in the hyp-exo-treated group. miR-10b-5p was enriched in nor-exo but not in hyp-exo. Dual-luciferase reporter gene assay found that both SMAD-specific E3 ubiquitin protein ligase 1 (Smurf1) and histone deacetylase 4 (HDAC4) mRNAs were inhibited by miR-10b-5p. The expression of neutral sphingomyelinase 2 (N-SMase2) was decreased in hypoxia ECFCs, and this result was consistent with the changes in miR-10b-5p in hyp-exo.

Conclusions

Due to a reduction of miR-10b-5p, which targets the fibrotic genes Smurf1 and HDAC4, the anti-fibrotic effects of hyp-exo were abolished.

Human cytokines activate JAK-STAT signaling pathway in porcine ocular tissue

Background

The JAK/STAT (Janus Tyrosine Kinase, Signal Transducers and Activators of Transcription) pathway is associated with cytokine or growth factor receptors and it is critical for growth control, developmental regulation and homeostasis. The use of porcine ocular cells as putative xenotransplants appears theoretically possible. The aim of this study was to investigate the response of various porcine ocular cells in vitro to human cytokines in regard to the activation of JAK-STAT signaling pathways.

Methods

Porcine lens epithelial cells, pigmented iris epithelial cells and pigmented ciliary body cells were used in this study. These cells were isolated from freshly enucleated porcine eyes by enzymatic digestion. Cultured cells between passages 3–8 were used in all experiments. Electromobility shift assay (EMSA), proliferation assay, immunofluorescence staining and flow cytometry were used to evaluate the JAK-STAT signaling pathway in these cells.

Results

JAK/STAT signaling pathways could be activated in porcine pigmented epithelial ciliary body cells, in pigmented iris epithelial cells and in lens epithelial cells in response to porcine and human interferons and cytokines. All cells showed very strong STAT1 activation upon stimulation with porcine interferon-gamma. Porcine ocular cells also respond to human cytokines; IFN-alpha induced strong activation of STAT1 in EMSA, flow cytometry and immunofluorescence experiments whereas activation of STAT3 was less strong in EMSA, but strong in flow cytometry and immunofluorescence. Human recombinant IL-6 activated STAT3 and human IL-4 activated STAT6. With the help of immunofluorescence assay and flow cytometry we observed nuclear localization of STAT proteins after activation of porcine ocular cells with cytokines and interferons. Human IFN-α had an inhibitory effect on porcine ocular cells in proliferation assays.

Conclusion

Our study demonstrated that some types of human cytokines and interferon activate intracellular JAK-STAT signaling pathways in porcine ocular cells. We hypothesize that direct stimulation of the JAK-STAT pathway in porcine cells in response to human cytokines will lead to complications or failure, if pig-to-human ocular tissue xenotransplantation were to be carried out. For successful xenotransplantation among other obstacles there must be new approaches developed to regulate signaling pathways.

The effects of extracellular matrix on cell attachment, proliferation and migration in a human lens epithelial cell line

Lens capsule consists of several kinds of extracellular matrix (ECM) which may play an important role in cell attachment, migration and proliferation of lens epithelial cells as a basement membrane. We have investigated the effects of ECM on cell attachment, proliferation and migration in a human lens epithelial (HLE) cell line. The HLE cell line, SRA 01/04, which was transfected with large T-antigen of SV40 was cultured in the absence of serum. Culture plates were coated with human type IV collagen, laminin or fibronectin. The number of cells were counted at 30-180 min and 3, 5 and 7 days of culture. The rate of BrdU incorporation was measured to study the cell proliferation. The cell migration was measured 1, 3, 5 and 7 days after seeding cells. Integrins, the receptors of ECM, were also detected using antibodies for the cell membrane antigens (CD49b, CD49c, CD49e) by an immunohistochemical method. Although less than 10% of cells attached to the non-coated plate and 50-60% of cells attached to the ECM-coated plates, there was no difference of cell attachment among each ECM used. The cell attachment was almost complete during the first 30 min of culture. Cell proliferation was not enhanced, but cell survival was aided by culture on the ECM components for up to 7 days. The area of cell attachment enlarged on the ECM-coated plates, whereas no migration was observed on the non-coated plate. These data indicate that ECM is the essential factor for cell attachment and increases migration of HLE cells.

Serum-free cultivation of human Tenon's capsule fibroblasts

PURPOSE

In the present study, the effect of three different serum-free and one serum-containing control medium on adhesion, proliferation, cryopreservation and PDGF-induced effects on cell proliferation of human Tenon's capsule fibroblasts (HTF) was compared.

MATERIALS AND METHODS

Third passage HTF were suspended in four different culture media (WM/F12, WM/F12/FCS 1%, LR-1, DMEM) and plating efficiency was determined after 24h using a cell counter system. Subsequently, cells were seeded at a density of 50/mm2 and cultured for ten days using the different culture media. Cell number was determined at day 2, 4, 7 and 10 after seeding. Furthermore, HTF cultured under the different conditions were stimulated by PDGF-BB [50 ng/ml]. Additionally, cell vitality after two weeks cryopreservation in five different culture media (WM/F12, WM/F12/FCS 1%, WM/F12/FCS 20%, LR-1, DMEM) was determined.

RESULTS

The plating efficiency of HTF when seeded in serum-free medium ranged from 55.3% to 59.6%. Using serum containing WM/F12/FCS 1% a slightly higher plating efficiency of 74.8% was obtained. Proliferation assays revealed population doublings of 0.77 with WM/F12/FCS 1% after an incubation period of 10 days. Cultivation of HTF using serum-free conditions did not cause significant cell proliferation but a slight cell loss which ranged from 23.1% to 34%. Addition of PDGF-BB resulted in a significant increase in cell proliferation with WM/F12/FCS 1%, WM/F12 and DMEM. After two weeks of cryopreservation in WM/F12, LR-1, DMEM, WM/F12/FCS 1% and WM/F12/FCS 20%, only the application of high serum concentrations led to sufficient preservation of cell vitality with a plating efficiency of 82.9%.

DISCUSSION

The results of the present study demonstrate that the use of serum-containing media is mandatory for cryopreservation of HTF. Seeding of cells can be performed either with serum or without serum. HTF cultured under serum-free conditions can be maintained quiescent with a sufficient number of cells remaining vital. The serum-free media used in this study can be applied for the investigation of cytokine effects on HTF.

Calcium mobilisation modulates growth of lens cells

The modulating effect of calcium cell signalling agonists on tissue growth was studied in a rabbit lens cell line (NN1003A). Calcium mobilisation was measured after Fura-2 incorporation and growth assayed either by direct Coulter counting or [3H]-thymidine incorporation. Transient increases in cytoplasmic calcium were elicited by rabbit serum, histamine, ATP and PDGF. Thapsigargin induced a prolonged increase and all of the above agonists failed to elicit a response after thapsigargin. Rabbit serum and PDGF both increased cell growth in a concentration-dependent manner. While histamine and ATP had little effect in serum-free medium, they reduced serum-stimulated growth. Acetylcholine and FGF did not produce a marked rise in cytoplasmic calcium and neither did they modulate growth. Both thapsigargin and caffeine greatly inhibited growth. These findings indicate that, in lens cells, agonists that mobilise calcium, whether by acting through G-protein or tyrosine kinase receptors, also modulate lens cell growth. Agents such as thapsigargin and caffeine that inactivate the same calcium store also inhibit growth.