1
|
Gallego-Muñoz P, Ibares-Frías L, Valsero-Blanco MC, Cantalapiedra-Rodriguez R, Merayo-Lloves J, Martínez-García MC. Effects of TGFβ1, PDGF-BB, and bFGF, on human corneal fibroblasts proliferation and differentiation during stromal repair. Cytokine 2017; 96:94-101. [PMID: 28390267 DOI: 10.1016/j.cyto.2017.03.011] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2016] [Revised: 02/22/2017] [Accepted: 03/31/2017] [Indexed: 12/27/2022]
Abstract
In an effort to improve the regenerative nature of corneal repair, this study reports the use of an in vitro human corneal fibroblasts (HCFs) wound model after treatment with three of the main growth factors (GFs) involved in corneal healing: transforming growth factor beta 1 (TGFβ1), platelet-derived growth factor BB-isoform (PDGF-BB), and basic fibroblast growth factor (bFGF) in order to delve in cell proliferation and differentiation processes. HCFs were mechanically wounded. The individual effect of TGFβ1, PDGF-BB, and bFGF on cell proliferation and differentiation during the repair process was studied at different time points until wound closure. Wound dimensions and morphological changes were evaluated by microscopy. Cell proliferation and myofibroblast differentiation were analyzed by immunofluorescence cytochemistry. Changes in cell morphology were apparent at Day 4. PDGF-BB- and bFGF-treated cells had fibroblast-like morphology. TGFβ1 stimulated proliferation in the wound edge and surrounding area, induced myofibroblast differentiation and inhibited cellular migration. PDGF-BB induced rapid wound closure due to proliferation, high motility, and late myofibroblast differentiation. The time course of closure induced by bFGF was similar to that for PDGF-BB, but was mostly due to proliferation in the wound area, and inhibited myofibroblast differentiation. Each of the GFs induced increases in responses promoting stromal repair differently. This study provides insight regarding how to optimize the outcome of stromal repair following corneal injury.
Collapse
Affiliation(s)
- Patricia Gallego-Muñoz
- Departamento de Biología Celular, Histología y Farmacología, Facultad de Medicina, Grupo de Investigación Reconocido: Técnicas Ópticas para el Diagnóstico, Universidad de Valladolid, Valladolid, Spain.
| | - Lucía Ibares-Frías
- Departamento de Biología Celular, Histología y Farmacología, Facultad de Medicina, Grupo de Investigación Reconocido: Técnicas Ópticas para el Diagnóstico, Universidad de Valladolid, Valladolid, Spain; Servicio de Oftalmología, Hospital Clínico Universitario de Valladolid, Valladolid, Spain
| | | | - Roberto Cantalapiedra-Rodriguez
- Departamento de Biología Celular, Histología y Farmacología, Facultad de Medicina, Grupo de Investigación Reconocido: Técnicas Ópticas para el Diagnóstico, Universidad de Valladolid, Valladolid, Spain
| | - Jesús Merayo-Lloves
- Instituto Oftalmológico Fernández-Vega, Universidad de Oviedo, Oviedo, Spain
| | - M Carmen Martínez-García
- Departamento de Biología Celular, Histología y Farmacología, Facultad de Medicina, Grupo de Investigación Reconocido: Técnicas Ópticas para el Diagnóstico, Universidad de Valladolid, Valladolid, Spain
| |
Collapse
|
2
|
Słoniecka M, Le Roux S, Boman P, Byström B, Zhou Q, Danielson P. Expression Profiles of Neuropeptides, Neurotransmitters, and Their Receptors in Human Keratocytes In Vitro and In Situ. PLoS One 2015. [PMID: 26214847 PMCID: PMC4516240 DOI: 10.1371/journal.pone.0134157] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Keratocytes, the quiescent cells of the corneal stroma, play a crucial role in corneal wound healing. Neuropeptides and neurotransmitters are usually associated with neuronal signaling, but have recently been shown to be produced also by non-neuronal cells and to be involved in many cellular processes. The aim of this study was to assess the endogenous intracellular and secreted levels of the neuropeptides substance P (SP) and neurokinin A (NKA), and of the neurotransmitters acetylcholine (ACh), catecholamines (adrenaline, noradrenaline and dopamine), and glutamate, as well as the expression profiles of their receptors, in human primary keratocytes in vitro and in keratocytes of human corneal tissue sections in situ. Cultured keratocytes expressed genes encoding for SP and NKA, and for catecholamine and glutamate synthesizing enzymes, as well as genes for neuropeptide, adrenergic and ACh (muscarinic) receptors. Keratocytes in culture produced SP, NKA, catecholamines, ACh, and glutamate, and expressed neurokinin-1 and -2 receptors (NK-1R and NK-2R), dopamine receptor D2, muscarinic ACh receptors, and NDMAR1 glutamate receptor. Human corneal sections expressed SP, NKA, NK-1R, NK-2R, receptor D2, choline acetyl transferase (ChAT), M3, M4 and M5 muscarinic ACh receptors, glutamate, and NMDAR1, but not catecholamine synthesizing enzyme or the α1 and β2 adrenoreceptors, nor M1 receptor. In addition, expression profiles assumed significant differences between keratocytes from the peripheral cornea as compared to those from the central cornea, as well as differences between keratocytes cultured under various serum concentrations. In conclusion, human keratocytes express an array of neuropeptides and neurotransmitters. The cells furthermore express receptors for neuropeptides/neurotransmitters, which suggests that they are susceptible to stimulation by these substances in the cornea, whether of neuronal or non-neuronal origin. As it has been shown that neuropeptides/neurotransmitters are involved in cell proliferation, migration, and angiogenesis, it is possible that they play a role in corneal wound healing.
Collapse
Affiliation(s)
- Marta Słoniecka
- Department of Integrative Medical Biology, Umeå University, Umeå, Sweden
- * E-mail:
| | - Sandrine Le Roux
- Department of Integrative Medical Biology, Umeå University, Umeå, Sweden
| | - Peter Boman
- Department of Integrative Medical Biology, Umeå University, Umeå, Sweden
| | - Berit Byström
- Department of Clinical Sciences, Ophthalmology, Umeå University, Umeå, Sweden
| | - Qingjun Zhou
- Department of Integrative Medical Biology, Umeå University, Umeå, Sweden
- Shandong Provincial Key Laboratory of Ophthalmology, Shandong Eye Institute, Qingdao, China
| | - Patrik Danielson
- Department of Integrative Medical Biology, Umeå University, Umeå, Sweden
- Department of Clinical Sciences, Ophthalmology, Umeå University, Umeå, Sweden
| |
Collapse
|
3
|
Petroll WM, Lakshman N, Ma L. Experimental models for investigating intra-stromal migration of corneal keratocytes, fibroblasts and myofibroblasts. J Funct Biomater 2012; 3:183-98. [PMID: 23482859 PMCID: PMC3589802 DOI: 10.3390/jfb3010183] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2012] [Revised: 03/10/2012] [Accepted: 03/13/2012] [Indexed: 11/16/2022] Open
Abstract
Following laser vision correction, corneal keratocytes must repopulate areas of cell loss by migrating through the intact corneal stroma, and this can impact corneal shape and transparency. In this study, we evaluate 3D culture models for simulating this process in vitro. Buttons (8 mm diameter) were first punched out of keratocyte populated compressed collagen matrices, exposed to a 3mm diameter freeze injury, and cultured in serum-free media (basal media) or media supplemented with 10% FBS, TGFβ1 or PDGF BB. Following freeze injury, a region of cell death was observed in the center of the constructs. Although cells readily migrated on top of the matrices to cover the wound area, a limited amount of cell migration was observed within the constructs. We next developed a novel "sandwich" model, which better mimics the native lamellar architecture of the cornea. Using this model, significant migration was observed under all conditions studied. In both models, cells in TGFβ and 10% FBS developed stress fibers; whereas cells in PDGF were more dendritic. PDGF stimulated the most inter-lamellar migration in the sandwich construct. Overall, these models provide insights into the complex interplay between growth factors, cell mechanical phenotypes and the structural properties of the ECM.
Collapse
Affiliation(s)
- W Matthew Petroll
- Department of Ophthalmology, University of Texas Southwestern Medical Center, Dallas, TX; (W.P.); (N.L.); (L.M.)
| | | | | |
Collapse
|
4
|
Lakshman N, Petroll WM. Growth factor regulation of corneal keratocyte mechanical phenotypes in 3-D collagen matrices. Invest Ophthalmol Vis Sci 2012; 53:1077-86. [PMID: 22247479 PMCID: PMC3339898 DOI: 10.1167/iovs.11-8609] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2011] [Revised: 12/07/2011] [Accepted: 01/03/2012] [Indexed: 11/24/2022] Open
Abstract
PURPOSE To assess how wound healing cytokines and the extracellular matrix (ECM) environment regulate the keratocyte mechanical phenotype. METHODS Rabbit corneal keratocytes were plated within standard bovine or rat tail type I collagen matrices (2.5 mg/mL), compressed collagen matrices (approximately 100 mg/mL), or on collagen-coated dishes and cultured for up to 7 days in serum-free media, platelet derived growth factor BB (PDGF BB), insulin-like growth factor (IGF), TGFβ1, TGFβ2, or FGF2. F-actin, α-smooth muscle actin (α-SMA) and collagen fibrils were imaged using confocal microscopy. Cell morphology, local matrix reorganization, and global matrix contraction were quantified digitally. RESULTS IGF and PDGF BB stimulated elongation of keratocytes and extension of dendritic processes within 3-D matrices, without inducing stress fiber formation or collagen reorganization. In contrast, treatment with TGFβ1 and TGFβ2 increased keratocyte contractility, as indicated by stress fiber formation and matrix compaction and alignment. This transformation was enhanced at higher cell densities within standard 3-D matrices, in which α-SMA was incorporated into stress fibers. In contrast, α-SMA was expressed within compressed 3-D matrices even at low cell density. FGF2 did not produce significant cytoskeletal or matrix reorganization in standard 3-D matrices; however, stress fibers were consistently expressed within compressed collagen matrices and on rigid two-dimensional substrates. Inhibiting Rho kinase blocked both TGFβ- and FGF2-induced stress fiber formation. CONCLUSIONS Keratocytes cultured in IGF or PDGF BB maintain a quiescent mechanical phenotype over a range of matrix environments. In contrast, the mechanical phenotypes induced by FGF and TGFβ vary in response to the structural and/or mechanical properties of the ECM.
Collapse
Affiliation(s)
- Neema Lakshman
- From the Department of Ophthalmology, University of Texas Southwestern Medical Center, Dallas, Texas
| | - W. Matthew Petroll
- From the Department of Ophthalmology, University of Texas Southwestern Medical Center, Dallas, Texas
| |
Collapse
|
5
|
Kim A, Lakshman N, Karamichos D, Petroll WM. Growth factor regulation of corneal keratocyte differentiation and migration in compressed collagen matrices. Invest Ophthalmol Vis Sci 2010; 51:864-75. [PMID: 19815729 PMCID: PMC2819331 DOI: 10.1167/iovs.09-4200] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2009] [Revised: 09/03/2009] [Accepted: 09/16/2009] [Indexed: 12/24/2022] Open
Abstract
PURPOSE To evaluate a novel 3D culture model of the corneal stroma and apply it to investigate how key wound-healing growth factors regulate the mechanics of corneal keratocyte migration. METHODS Rabbit corneal keratocytes were seeded within collagen matrices that were compacted using external compression. Six-millimeter-diameter buttons were then incubated in media supplemented with 10% FBS, TGFbeta1, TGFbeta2, platelet-derived growth factor (PDGF), or no growth factor (control). After 1, 3, or 7 days, matrices were labeled with phalloidin and a nucleic acid dye, and were imaged using laser confocal microscopy. To study cell migration, buttons were nested within acellular uncompressed outer collagen matrices before growth factor stimulation. RESULTS Corneal keratocytes in basal media within compressed matrices had a broad, convoluted cell body and thin dendritic processes. In contrast, cells in 10% FBS developed a bipolar fibroblastic morphology. Treatment with TGFbeta induced the formation of stress fibers expressing alpha-smooth muscle actin, suggesting myofibroblast transformation. PDGF induced keratocyte elongation without inducing stress fiber formation. Both 10% FBS and PDGF stimulated significant keratocyte migration through the uncompressed outer matrix, but 10% FBS produced more cell-induced collagen matrix reorganization. TGFbeta induced the smallest increase in migration and the greatest matrix reorganization. CONCLUSIONS Corneal keratocytes are able to differentiate normally and respond to growth factors within compressed collagen matrices, which provide a high-stiffness, 3D environment, similar to native stromal tissue. In addition, nesting these matrices provides a unique platform for investigating the mechanics of keratocyte migration after exposure to specific wound-healing cytokines.
Collapse
Affiliation(s)
- Areum Kim
- From the Department of Ophthalmology, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Neema Lakshman
- From the Department of Ophthalmology, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Dimitris Karamichos
- From the Department of Ophthalmology, University of Texas Southwestern Medical Center, Dallas, Texas
| | - W. Matthew Petroll
- From the Department of Ophthalmology, University of Texas Southwestern Medical Center, Dallas, Texas
| |
Collapse
|
6
|
Lakshman N, Kim A, Petroll WM. Characterization of corneal keratocyte morphology and mechanical activity within 3-D collagen matrices. Exp Eye Res 2009; 90:350-9. [PMID: 20025872 DOI: 10.1016/j.exer.2009.11.016] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2009] [Revised: 11/24/2009] [Accepted: 11/25/2009] [Indexed: 12/18/2022]
Abstract
The purpose of this study was to assess quantitatively the differences in morphology, cytoskeletal organization and mechanical behavior between quiescent corneal keratocytes and activated fibroblasts in a 3-D culture model. Primary cultures of rabbit corneal keratocytes and fibroblasts were plated inside type I collagen matrices in serum-free media or 10% FBS, and allowed to spread for 1-5 days. Following F-actin labeling using phalloidin, and immunolabeling of tubulin, alpha-smooth muscle actin or connexin 43, fluorescent and reflected light (for collagen fibrils) 3-D optical section images were acquired using laser confocal microscopy. In other experiments, dynamic imaging was performed using differential interference contrast microscopy, and finite element modeling was used to map ECM deformations. Corneal keratocytes developed a stellate morphology with numerous cell processes that ran a tortuous path between and along collagen fibrils without any apparent impact on their alignment. Fibroblasts on the other hand, had a more bipolar morphology with pseudopodial processes (P </= 0.001). Time-lapse imaging of keratocytes revealed occasional extension and retraction of dendritic processes with only transient displacements of collagen fibrils, whereas fibroblasts exerted stronger myosin II-dependent contractile forces (P < 0.01), causing increased compaction and alignment of collagen at the ends of the pseudopodia (P < 0.001). At high cell density, both keratocytes and fibroblasts appeared to form a 3-D network connected via gap junctions. Overall, this experimental model provides a unique platform for quantitative investigation of the morphological, cytoskeletal and contractile behavior of corneal keratocytes (i.e. their mechanical phenotype) in a 3-D microenvironment.
Collapse
Affiliation(s)
- Neema Lakshman
- Department of Ophthalmology, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, TX 75390-9057, USA
| | | | | |
Collapse
|
7
|
Crabb RAB, Chau EP, Evans MC, Barocas VH, Hubel A. Biomechanical and microstructural characteristics of a collagen film-based corneal stroma equivalent. ACTA ACUST UNITED AC 2006; 12:1565-75. [PMID: 16846352 DOI: 10.1089/ten.2006.12.1565] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The growth in refractive surgeries and corneal replacements has fueled interest in the development of a tissue-engineered cornea. This study characterizes the microstructure and biomechanical properties of film-based corneal stroma equivalents over time in culture. The increased collagen density in the films was hypothesized to result in improved mechanical properties both initially and over time. The microstructure of the film-based stromal equivalent was examined using atomic force microscopy and scanning electron microscopy; the mechanical properties, relaxed modulus, and ultimate tensile strength were quantified using uniaxial tensile testing. The dense, film-based stromal equivalent had a lamellae-like microstructure, which was notably different than the porous structure of sponges used previously. Seeded human corneal stromal fibroblasts remained on the surface of the film rather than migrating into the film and produced fibers of extracellular matrix with diameters of 35-75 nm. After an initial decrease during hydration, the relaxed modulus and ultimate tensile strength for fully hydrated collagen films were 0.4 +/- 0.2 MPa and 0.3 +/- 0.1 MPa, respectively. The mechanical properties of cell-seeded films mimicked those of control films. While further studies are needed to quantify the optical properties, the dense, lamellae-like structure of collagen films is a feasible scaffold for the development of tissue-engineered stroma.
Collapse
Affiliation(s)
- Rachael A B Crabb
- Department of Biomedical Engineering, University of Minnesota, Minneapolis, Minnesota 55455, USA
| | | | | | | | | |
Collapse
|
8
|
Kawakita T, Espana EM, He H, Smiddy R, Parel JM, Liu CY, Tseng SCG. Preservation and expansion of the primate keratocyte phenotype by downregulating TGF-beta signaling in a low-calcium, serum-free medium. Invest Ophthalmol Vis Sci 2006; 47:1918-27. [PMID: 16638999 PMCID: PMC1569676 DOI: 10.1167/iovs.05-1040] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
PURPOSE To demonstrate whether the original keratocyte phenotype is maintained with proliferative activity by suppressing TGF-beta signaling in rhesus monkey keratocytes expanded in a serum-free and low-[Ca2+] medium. METHODS Rhesus monkey keratocytes were isolated from central corneal buttons by collagenase digestion for 16 hours, seeded on plastic in Dulbecco's modified Eagle's medium (DMEM) containing insulin-transferrin-sodium selenite (ITS) supplement (DMEM/ITS) or 10% fetal bovine serum (DMEM/10% FBS), or in a defined keratinocyte serum-free medium (KSFM). After confluence, cells in KSFM were continuously subcultured at a 1-to-3 split. Cellular proliferation was analyzed by immunostaining for Ki67 and the MTT assay. The cellular phenotype was determined by immunostaining for aldehyde dehydrogenase (ALDH), keratocan, and CD34 and by the expression of keratocan promoter-driven enhanced cyan fluorescent protein (ECFP). The stability of the keratocyte phenotype was examined by switching KSFM to DMEM/ITS and DMEM/10% FBS. TGF-beta signaling was monitored by measuring the promoter activity of TGF-beta1, -beta2, and -beta RII after transient adenoviral transfection, and cytolocalization of Smad2 and Smad4. RESULTS In KSFM, monkey keratocytes proliferated while maintaining the expression of keratocan, CD34, and ALDH proteins and keratocan promoter-driven ECFP for at least 15 passages. The nuclear accumulation of Smad2 and Smad4 and the promoter activities of TGF-beta1 and -beta RII were significantly downregulated in KSFM compared with DMEM/10% FBS. In KSFM, an increase of [Ca2+] to 1.8 mM and addition of 10% FBS synergistically downregulated the keratocan promoter activity, facilitated Smad2 and Smad4 nuclear translocation, and upregulated TGF-beta1 and -beta RII promoter activities. CONCLUSIONS The normal monkey keratocyte phenotype can be maintained in a low-calcium, serum-free medium by downregulating Smad-mediated TGF-beta signaling.
Collapse
Affiliation(s)
- Tetsuya Kawakita
- From TissueTech, Inc., Ocular Surface Center, Miami, Florida; and the
| | - Edgar M. Espana
- From TissueTech, Inc., Ocular Surface Center, Miami, Florida; and the
| | - Hua He
- From TissueTech, Inc., Ocular Surface Center, Miami, Florida; and the
| | - Robert Smiddy
- From TissueTech, Inc., Ocular Surface Center, Miami, Florida; and the
| | - Jean-Marie Parel
- Ophthalmic Biophysics Center, Bascom Palmer Eye Institute, University of Miami School of Medicine, Miami, Florida
| | - Chia-Yang Liu
- Ophthalmic Biophysics Center, Bascom Palmer Eye Institute, University of Miami School of Medicine, Miami, Florida
| | - Scheffer C. G. Tseng
- From TissueTech, Inc., Ocular Surface Center, Miami, Florida; and the
- Corresponding author: Scheffer C. G. Tseng, Ocular Surface Center, 7000 SW 97 Avenue, Suite 213, Miami, FL 33176;
| |
Collapse
|
9
|
Abstract
According to the "classical" doctrine, resident cells of the cornea include the stratified epithelial cells, quiescent keratocytes, and a single layer of nondividing endothelial cells. However, it has become increasingly evident that other cell types are involved in the homeostasis of the cornea. The presence of various cell types from different lineages has raised concern among researchers as to what we are actually "seeing" in the cornea. Although definitive conclusions cannot yet be drawn, this review attempts to clarify the various accessory cell types reported in the human and murine cornea. The epithelial layer of the limbal area includes melanocytes, as well as antigen-presenting cells that are also present in the peripheral clear cornea. The most debated tissue currently is perhaps the corneal stroma, where resident keratocytes are not as large a population as was previously believed. Bone marrow-derived cells are found in the cornea, and these may not express the typical HLA molecules usually found on the surface of antigen-presenting cells. Nerve fibers extend though the superficial stroma to form a plexus beneath the epithelium. Although the cell body of the neuron itself is not in the cornea, neural glial cells, such as Schwann cells, are present in the stroma. The use of specific molecular markers and high-quality imaging techniques will be required to fully elucidate the various accessory cells of the cornea and their function.
Collapse
Affiliation(s)
- Shigeto Shimmura
- Department of Ophthalmology, Keio University School of Medicine, Tokyo, Japan.
| | | |
Collapse
|
10
|
Kawakita T, Espana EM, He H, Hornia A, Yeh LK, Ouang J, Liu CY, Tseng SCG. Keratocan expression of murine keratocytes is maintained on amniotic membrane by down-regulating transforming growth factor-beta signaling. J Biol Chem 2005; 280:27085-92. [PMID: 15908433 PMCID: PMC1282515 DOI: 10.1074/jbc.m409567200] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Keratocytes in the corneal stroma express keratan sulfate-containing proteoglycans including cornea-specific keratocan. On plastic dishes, human, bovine, and rabbit keratocytes lose their characteristic dendritic morphology and keratocan expression when cultured in serum-containing media. Herein, we demonstrated that murine keratocytes also acquired a fibroblastic shape and lost keratocan expression after first passage when cultured on plastic in the presence of serum. In contrast, cells expanded on human amniotic membrane (AM) stromal matrix maintained a three-dimensional dendritic morphology and expressed keratocan mRNA and protein for at least 8 passages before senescence. When keratocytes were cultured on AM, the promoter activity of transforming growth factor (TGF)-beta2 and TGF-beta receptor II was down-regulated as compared with that on plastic. Furthermore, cells on AM continuously retained Smad 2 and Smad 4 in the cytoplasm and did not express alpha-smooth muscle actin, even when 10 ng/ml TGF-beta1 was added in a serum-free medium for up to 5 days. In parallel to such down-regulation of TGF-beta signaling, keratocan promoter-driven ECFP expression was observed in cells cultured either on AM in the presence of serum or on plastic containing serum treated with a neutralizing antibody to TGF-beta. Collectively, these results indicate that down-regulation of Smad-mediated TGF-beta signaling is an important mechanism for cultured keratocytes to maintain a normal phenotype while continuously expanded in a serum-containing medium. This strategy of suppressing TGF-beta signaling, achieved by AM stromal matrix in part via suppression of TGF-beta gene transcription, can be used to expand keratocytes in culture without the use of AM in the future.
Collapse
Affiliation(s)
- Tetsuya Kawakita
- From TissueTech, Inc. and Ocular Surface Center, Miami, Florida, 33173 and
| | - Edgar M. Espana
- From TissueTech, Inc. and Ocular Surface Center, Miami, Florida, 33173 and
| | - Hua He
- From TissueTech, Inc. and Ocular Surface Center, Miami, Florida, 33173 and
| | - Armand Hornia
- From TissueTech, Inc. and Ocular Surface Center, Miami, Florida, 33173 and
| | - Lung-Kun Yeh
- Bascom Palmer Eye Institute, University of Miami School of Medicine, Miami, Florida, 33136
| | - Jie Ouang
- Bascom Palmer Eye Institute, University of Miami School of Medicine, Miami, Florida, 33136
| | - Chia-Yang Liu
- Bascom Palmer Eye Institute, University of Miami School of Medicine, Miami, Florida, 33136
| | - Scheffer C. G. Tseng
- From TissueTech, Inc. and Ocular Surface Center, Miami, Florida, 33173 and
- Address correspondence to: Scheffer C. G. Tseng, MD, PhD, Ocular Surface Center, 7000 SW 97 Avenue, Suite 213, Miami, FL 33173, Tel. (305) 274-1299; Fax. (305) 274-1297; E-mail:
| |
Collapse
|
11
|
Jester JV, Ho-Chang J. Modulation of cultured corneal keratocyte phenotype by growth factors/cytokines control in vitro contractility and extracellular matrix contraction. Exp Eye Res 2003; 77:581-92. [PMID: 14550400 DOI: 10.1016/s0014-4835(03)00188-x] [Citation(s) in RCA: 180] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The purpose of this study was to evaluate specific keratocyte phenotypes (keratocyte, fibroblast, myofibroblast) for cell contractility and ability to contract extracellular matrix. Rabbit keratocyte phenotype was modulated by exposure to optimal proliferative doses of IGF-I, IL-1alpha, FGF2, PDGF-AB, and TGFbeta(1). Cells were then evaluated by immunocytochemistry, western blot, collagen gel contraction and LPA stimulation to measure: (1) focal adhesion (FA), fibronectin (FN) and f-actin assembly; (2) expression of alpha-smooth muscle actin (alpha-SMA); (3) ability to contract extracellular matrix and (4) determine contractile ability, respectively. Untreated keratocytes showed no ability to contract collagen matrix. IGF-I and IL-1alpha increased cell proliferation (70.2 and 74.3%, respectively) but did not alter keratocyte phenotype or ability to contract matrix. FGF2 and PDGF induced fibroblast differentiation with FA and FN assembly and significant (p<0.05) extracellular matrix contraction. TGFbeta(1) induced myofibroblast differentiation with prominent FA and FN assembly, expression of alpha-SMA and significantly greater (p<0.05) matrix contraction. Addition of LPA induced actin filament assembly in growth factor starved fibroblasts and myofibroblasts but had no effect on the cultured keratocyte phenotype. We report for the first time that the keratocyte phenotype is non-contractile and that cell quiescence is not a defining characteristic. We further establish that changes in environmental conditions modulate the keratocyte phenotype resulting in physiologically functional differences regarding cell contractility and capacity to contract extracellular matrix.
Collapse
Affiliation(s)
- James V Jester
- Department of Ophthalmology, University of Texas Southwestern Medical Center at Dallas, 5323 Harry Hines Boulevard, Dallas, TX 75390-9057, USA.
| | | |
Collapse
|
12
|
Ogata N, Takahashi I, Nakazawa K. Purification and characterization of chick corneal beta-D-glucuronyltransferase involved in chondroitin sulfate biosynthesis. Biol Pharm Bull 2002; 25:1282-8. [PMID: 12392079 DOI: 10.1248/bpb.25.1282] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Beta-D-Glucuronyltransferase, which transfers D-glucuronic acid (GlcA) from UDP-GlcA to N-acetyl-D-galactosamine (GalNAc) at the nonreducing end of chondro-pentasaccharide-PA (pyridylamino-), GalNAcbeta1-(4GlcAbeta1-3GalNAcbeta1)2-PA, was purified 339-fold with an 11.0% yield from 2-d-old chick corneas by chromatography on DEAE-Sepharose, WGA-agarose, heparin-Sepharose, and 1st and 2nd UDP-GlcA-agarose (in the presence of Gal) columns. The activity was detected by fluorescence of PA residues of the product. The purified enzyme has an optimum pH of 7.0 (Mes buffer), and much higher activity toward chondro-heptasaccharide-PA than toward the chondro-pentasaccharide-PA, but no activity toward p-nitrophenyl-beta-GalNAc. The enzyme activity was almost completely inhibited by GalNAc (20 mm). Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) of the purified enzyme fraction showed one band of 38 kDa with many other bands. The amino acid sequence was determined for the tryptic digests of the 38 kDa band protein. The sequences determined showed no homology to those of several beta-glucuronyltransferases reported previously. It seems that the enzyme is involved in the elongation of chondroitin sulfate chains in vivo.
Collapse
Affiliation(s)
- Nana Ogata
- Section of Radiochemistry, Meijo University, Nagoya, Japan
| | | | | |
Collapse
|
13
|
Yamamoto Y, Takahashi I, Ogata N, Nakazawa K. Purification and characterization of N-acetylglucosaminyl sulfotransferase from chick corneas. Arch Biochem Biophys 2001; 392:87-92. [PMID: 11469798 DOI: 10.1006/abbi.2001.2422] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
N-Acetylglucosaminyl(GlcNAc) sulfotransferase, which transfers sulfate from adenosine 3'-phosphate 5'-phosphosulfate to GlcNAc at the nonreducing end of oligosaccharides, was purified 887-fold with a 8.4% yield from 2-day-old chick corneas by chromatography on CM-Sepharose, WGA-agarose, GlcNAc-agarose, and 3',5'-ADP-agarose columns. The purified enzyme has an optimum pH of 6.0 (Mes buffer) and specifically transfers a sulfate to GlcNAc at the nonreducing end but not to internal GlcNAc. The enzyme was stimulated by protamine and Mn(2+). SDS-polyacrylamide gel electrophoresis of the purified enzyme still showed two main bands (66 and 55 kDa) with some minor bands. It appears that this enzyme competes with beta-galactosyltransferase in binding to the nonreducing GlcNAc residue on KS synthesis; this suggests that the sulfation of the GlcNAc residue is coupled with the elongation of the KS chain.
Collapse
Affiliation(s)
- Y Yamamoto
- Section of Radiochemistry, Faculty of Pharmacy, Meijo University, 150 Yagotoyama, Tempaku-ku, Nagoya 468-8503, Japan
| | | | | | | |
Collapse
|
14
|
Takahashi I, Sashima S, Nakazawa K. Comparative analysis of proteoglycans synthesized by chick corneal stromal cells in cell culture and organ culture. Biol Pharm Bull 2001; 24:27-33. [PMID: 11201241 DOI: 10.1248/bpb.24.27] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Proteoglycans (PGs) synthesized by chick corneal stromal cells in cell culture and organ culture were metabolically radiolabelled with [35S]sulfate (for glycosaminoglycans) and [3H]leucine (for core proteins). Media, cell extracts and organ extracts from cultures were chromatographed on DEAE-Sephacel columns and separated into three fractions: the pass-through fraction (Fraction 1: nonsulfated PGs, hardly sulfated PGs, or glycoproteins with some oligosaccharides), the fraction eluted with a low salt concentration (Fraction 2: undersulfated PGs), and the fraction eluted with a high salt concentration (Fraction 3: highly sulfated PGs). The PG compositions of each fraction of cell culture and organ culture were then compared. While the proportions of highly sulfated KSPG in Fractions 3 of medium and cell extract of cell culture were both very low compared with those of medium and organ extract of organ culture, respectively, the proportions of highly sulfated CS/DS PG in Fractions 3 of those of cell culture were higher than those of organ culture. On the other hand, the proportions in the 35S activities of nonsulfated or undersulfated KSPG in Fractions 1 and 2 of medium and cell extract of cell culture were comparable to those of organ culture. Furthermore, the proportions of core proteins of undersulfated KSPG in Fractions 2 were higher in cell culture than in organ culture. These results show that, when the cells are cell-cultured, the degree of sulfation of KS chains decreases markedly, but the syntheses of the glycosaminoglycan backbone and core protein are maintained.
Collapse
Affiliation(s)
- I Takahashi
- RI Center, Faculty of Pharmacy, Meijo University, Nagoya, Japan
| | | | | |
Collapse
|
15
|
Nakazawa K, Takahashi I, Yamamoto Y. Glycosyltransferase and sulfotransferase activities in chick corneal stromal cells before and after in vitro culture. Arch Biochem Biophys 1998; 359:269-82. [PMID: 9808769 DOI: 10.1006/abbi.1998.0897] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The expression type of proteoglycan in corneal stromal cells is known to change markedly when the cells are cultured in vitro. To determine which enzyme is primarily responsible for this change in chick corneal stromal cells, the activities of various glycosyltransferases and sulfotransferases were determined before and after in vitro culture of the cells. The activities of N-acetylglucosaminyltransferase, galactosyltransferase, and sulfotransferase, which are involved in keratan sulfate synthesis, were assayed using pyridylaminated N-acetyllactosamine-containing oligosaccharides as acceptor substrate; the activities of N-acetylgalactosaminyltransferase, glucuronyltransferase, and sulfotransferase, which are involved in chondroitin sulfate synthesis, were assayed using pyridylaminated chondrooligosaccharides as acceptor substrate. Of these enzymes, the sulfotransferase activity toward degalactosylated, pyridylaminated lacto-N-neotetraose and N-acetyllactosamine dimer (probably GlcNAc-6-sulfotransferase) decreased markedly after in vitro culture, whereas the galactosyltransferase activity increased. The chondroitin sulfate-sulfotransferase activities toward pyridylaminated chondrooligosaccharides hardly changed after in vitro culture. The marked decrease in the activity of the keratan sulfate-sulfotransferase corresponds to the marked decrease in keratan sulfate biosynthesis when the cells are cultured in vitro. These findings suggest that keratan sulfate-sulfotransferase (GlcNAc-6-sulfotransferase) is a key enzyme in keratan sulfate biosynthesis and that its decrease is primarily responsible for the marked decrease in keratan sulfate synthesis after in vitro culture.
Collapse
Affiliation(s)
- K Nakazawa
- Faculty of Pharmacy, Meijo University, 150 Yagotoyama, Nagoya, Tempaku-ku, 468-8503, Japan.
| | | | | |
Collapse
|
16
|
Schrecengost PK, Blochberger TC, Hassell JR. Identification of chick corneal keratan sulfate proteoglycan precursor protein in whole corneas and in cultured corneal fibroblasts. Arch Biochem Biophys 1992; 292:54-61. [PMID: 1727651 DOI: 10.1016/0003-9861(92)90050-7] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The precursor protein to the chick corneal keratan sulfate proteoglycan was identified by immunoprecipitation with antiserum to its core protein from lysates of [35S]methionine-pulsed corneas and corneal fibroblasts in cell culture. Antiserum to the keratan sulfate proteoglycan immunoprecipitated a doublet of Mr 52,000 and 50,000 and minor amounts of a Mr 40,000 protein from pulsed corneas. Pulse-chase experiments, which permitted the conversion of the precursor proteins to proteoglycans and digestion of the glycosaminoglycans on immunoprecipitated proteoglycans with keratanase or chondroitinase ABC, showed that the Mr 52,000-50,000 doublet was converted to a keratan sulfate proteoglycan and the Mr 40,000 protein was converted to a chondroitin sulfate proteoglycan. Chick corneal fibroblasts in cell culture primarily produced the smaller (Mr50,000) precursor protein, and in the presence of tunicamycin the precursor protein size was reduced to Mr35,000, which indicates that the core protein contains approximately five N-linked oligosaccharides. Pulse-chase experiments with corneal fibroblasts in culture showed that the precursor protein was processed and secreted into the medium. However, its sensitivity to endo-beta-galactosidase and resistance to keratanase indicate that the precursor protein was converted to a glycoprotein with large oligosaccharides and not to a proteoglycan. This suggests that, although the precursor protein for the proteoglycan is produced in cultured corneal fibroblasts, the sulfation enzymes for keratan sulfate may be absent.
Collapse
Affiliation(s)
- P K Schrecengost
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Pennsylvania
| | | | | |
Collapse
|
17
|
|
18
|
S. Dahl IM. Bosynthesis of proteoglycans and hyaluronate in human fibroblast cultures established from normal and pathological corneas. Exp Eye Res 1981. [DOI: 10.1016/s0014-4835(81)80022-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
|