Differential effects of TGF-β and FGF-2 on in vitro proliferation and migration of primate retinal endothelial and Müller cells

Multiple Endocrine Neoplasia Type 1 Regulates TGFβ-Mediated Suppression of Tumor Formation and Metastasis in Melanoma

Over the past few decades, the worldwide incidence of cutaneous melanoma, a malignant neoplasm arising from melanocytes, has been increasing markedly, leading to the highest rate of skin cancer-related deaths. While localized tumors are easily removed by excision surgery, late-stage metastatic melanomas are refractory to treatment and exhibit a poor prognosis. Consequently, unraveling the molecular mechanisms underlying melanoma tumorigenesis and metastasis is crucial for developing novel targeted therapies. We found that the multiple endocrine neoplasia type 1 (MEN1) gene product Menin is required for the transforming growth factor beta (TGFβ) signaling pathway to induce cell growth arrest and apoptosis in vitro and prevent tumorigenesis in vivo in preclinical xenograft models of melanoma. We further identified point mutations in two MEN1 family members affected by melanoma that led to proteasomal degradation of the MEN1 gene product and to a loss of TGFβ signaling. Interestingly, blocking the proteasome degradation pathway using an FDA-approved drug and RNAi targeting could efficiently restore MEN1 expression and TGFβ transcriptional responses. Together, these results provide new potential therapeutic strategies and patient stratification for the treatment of cutaneous melanoma.

Comparison of the effects of EGF, FGF-b, and NGF on the proliferation, migration, and reprogramming of primary rat Müller cells

Purpose

During the healing process of full-thickness macular holes (FTMHs), the closure and recovery of the hole depend on the migration, proliferation, and activation of Müller cells to promote the closure of holes and restoration of the photosensitive layer. In this study, we investigated the ability of the epidermal growth factor (EGF), fibroblast growth factor-basic (FGF-b), and nerve growth factor (NGF) to influence this process by regulating proliferation, migration, and reprogramming of primary rat Müller cells.

Methods

Cell proliferation was measured using CCK8 [2- (2-Methoxy-4-nitrophenyl)-3- (4-nitrophenyl)-5- (2,4-disulfophenyl)-2H-tetrazolium Sodium Salt] colorimetric assays and EdU [5-Ethynyl-2'-deoxyuridine] assays over 48 h. Cell migration was measured using scratch-wound assays and transwell migration assays over 48 h. In addition, we conducted Western blot assays and immunofluorescence assays on cells that were specially treated for 1, 3, and 5 days for cell reprogramming. The percentage of EdU-positive cells in Nestin-positive have also been tested by co-immunofluorescence (Co-IF) staining.

Results

EGF and FGF-b significantly promoted the proliferation of Müller cells (p < 0.05) at a concentration of 0-50 ng/mL, but NGF did not (p > 0.05), compared to untreated controls. Exogenous FGF-b and EGF promote the reprogramming of primary rat Müller cells, significantly enhancing the neural stem cell marker Nestin after stimulation on the 1st, 3rd, and 5th days, respectively. The expression of Müller cell marker Vimentin was significantly (p < 0.05) reduced during this period compared to the control group. However, there was no significant difference between the NGF and control groups. Furthermore, the EGF group expressed stronger Nestin expression than the SCM group. The Co-IF staining showed that early 50% of activated cells came from newly proliferating cells on the 5th day.

Conclusion

These observations suggest that FGF-b can promote the activation of Müller cells in a short time and enhance the possessive features of neural stem cells, while EGF may act for a longer period of time. This may further the understanding of growth factor therapy in treating FTMHs, and Müller glia may be promising candidates for cell replacement therapy.

Application of IPSC and Müller glia derivatives in retinal degenerative diseases

Retinal degenerative diseases cause blindness characterized by a progressive decline in the number and function of retinal pigment epithelium (RPE), photoreceptor cells, and ganglion cells. Such diseases include retinitis pigmentosa (RP), glaucomatous optic neuropathy, age-related macular degeneration and diabetic optic neuropathy. Recent studies have demonstrated that Müller glial cells (MGCs), an endogenous alternative source of retinal neurons, are important glial cells involved in retinal development, damage, and regeneration, making it an excellent target for retinal nerve regeneration. Although hardly differentiate into neuron cells, transplanted MGCs have been shown to induce partial recovery of visual function in experimental retinal degenerative models. This improvement is possibly attributed to the release of neuroprotective factors that derived from the MGCs. With the development of the therapeutic usage of pluripotent stem cell, application of induced pluripotent stem cells (iPSCs) or embryonic stem cells (ESCs) originated derivation of MGCs have been widely used in retinal degenerative disease model such as glaucoma and retinitis pigmentosa model. This chapter summarized the relevant research and mechanisms and provided a broader application and research prospects for effective treatments in retinal degenerative diseases.

Plumbagin Inhibits Proliferation, Migration, and Invasion of Retinal Pigment Epithelial Cells Induced by FGF-2

Proliferative vitreoretinopathy (PVR) is a serious ophthalmic disease and characterized by the formation of proliferative membranes by retinal pigment epithelial (RPE) cells. In PVR, the contraction and traction of the fibrocellular membranes cause retinal detachment, which can cause reduction surgery for retinal detachment to fail. Fibroblast growth factor-2 (FGF-2) causes RPE cells to form extracellular matrix (ECM), promotes chemotaxis, mitosis, and positively promotes the disease process of PVR. Plumbagin (PLB) is a plant small molecule naphthoquinone compound. It has the functions in anti-tumor, anti-inflammatory, inhibit proliferation. We tried to investigate the possible effects of PLB on the biological behavior of ARPE-19 cells induced by FGF-2 and its underlying mechanisms. Our study confirmed that proliferation, migration, and invasion of ARPE-19 cells induced by FGF-2 (10 ng/ml) were significantly inhibited by PLB. PLB also significantly inhibits the expression of MMP-2/-9, collagen I Alpha 1 (Col1A1), collagen IV Alpha 1 (Col4A1), collagen VI Alpha 1 (Col6A1), and the phosphorylation of FGF receptor (FGFR)-1, FGFR-2, ERK, p38, JNK of FGF-2-induced ARPE-19 cells. In summary, PLB inhibits FGF-2-stimulated proliferation, migration, and invasion of ARPE-19 cells, which may take place through inhibiting the expression of MMP-2/-9, Col1A1, Col4A1, Col6A1, and the mitogen-activated protein kinase (MAPK) pathway. PLB may have a preventive effect on proliferation, migration, and invasion of FGF-2-induced ARPE-19 cells.

Exogenous FGF-2 prolongs endothelial connection in multilayered human skeletal muscle cell sheet

Angiogenesis is a pressing issue in tissue engineering associated with restoration of blood supply to ischemic tissues and promotion of rapid vascularization of tissue-engineered grafts. Fibroblast growth factor-2 (FGF-2) plays a vital role in processes such as angiogenesis and is an attractive candidate for tissue engineering. While skeletal muscle tissue engineering is established, the role of FGF-2 in endothelial function to promote angiogenesis after transplantation is unclear. Here, a culture system comprising a five-layered sheet of human skeletal muscle cells co-incubated on green fluorescent protein-expressing human umbilical vein endothelial cells (GFP-HUVECs) mimicking in vivo angiogenesis was used to investigate the role of FGF-2 in vascularization of engineered tissues. The basal level of FGF-2 in cultured media of skeletal muscle cell sheets was undetectable. Therefore, cell sheets co-incubated with GFP-HUVECs were exogenously treated with 10 ng/mL FGF-2, and endothelial network formation was evaluated. After prolonged culture, the endothelial network length and connectivity increased following treatment with FGF-2 as compared with control treatment. The numbers of medium and long endothelial networks significantly increased inside the sheet longer than 0.2 and 0.4 cm, respectively, after FGF-2 treatment. Time-lapse microscopy monitoring dynamic endothelial behavior revealed that FGF-2-mediated maintenance of endothelial connection and retardation of endothelial network disconnection after 72 h. The present study suggests the precise role of FGF-2 in maintaining endothelial connection and the extent of the endothelial network in skeletal muscle cell sheets. This understanding can be applied to design in vitro pre-vascularized tissue and graft integration prospects.

Microfluidic and Microscale Assays to Examine Regenerative Strategies in the Neuro Retina

Bioengineering systems have transformed scientific knowledge of cellular behaviors in the nervous system (NS) and pioneered innovative, regenerative therapies to treat adult neural disorders. Microscale systems with characteristic lengths of single to hundreds of microns have examined the development and specialized behaviors of numerous neuromuscular and neurosensory components of the NS. The visual system is comprised of the eye sensory organ and its connecting pathways to the visual cortex. Significant vision loss arises from dysfunction in the retina, the photosensitive tissue at the eye posterior that achieves phototransduction of light to form images in the brain. Retinal regenerative medicine has embraced microfluidic technologies to manipulate stem-like cells for transplantation therapies, where de/differentiated cells are introduced within adult tissue to replace dysfunctional or damaged neurons. Microfluidic systems coupled with stem cell biology and biomaterials have produced exciting advances to restore vision. The current article reviews contemporary microfluidic technologies and microfluidics-enhanced bioassays, developed to interrogate cellular responses to adult retinal cues. The focus is on applications of microfluidics and microscale assays within mammalian sensory retina, or neuro retina, comprised of five types of retinal neurons (photoreceptors, horizontal, bipolar, amacrine, retinal ganglion) and one neuroglia (Müller), but excludes the non-sensory, retinal pigmented epithelium.

Inflammatory and Fibrogenic Factors in Proliferative Vitreoretinopathy Development

Purpose

Proliferative vitreoretinopathy (PVR) occurs in 5%-10% of rhegmatogenous retinal detachment cases and is the principle cause for failure of retinal reattachment surgery. Although there are a number of surgical adjunctive agents available for preventing the development of PVR, all have limited efficacy. Discovering predictive molecular biomarkers to determine the probability of PVR development after retinal reattachment surgery will allow better patient stratification for more targeted drug evaluations.

Methods

Narrative literature review.

Results

We provide a summary of the inflammatory and fibrogenic factors found in ocular fluid samples during the development of retinal detachment and PVR and discuss their possible use as molecular PVR predictive biomarkers.

Conclusions

Studies monitoring the levels of the above factors have found that few if any have predictive biomarker value, suggesting that widening the phenotype of potential factors and a combinatorial approach are required to determine predictive biomarkers for PVR.

Translational Relevance

The identification of relevant biomarkers relies on an understanding of disease signaling pathways derived from basic science research. We discuss the extent to which those molecules identified as biomarkers and predictors of PVR relate to disease pathogenesis and could function as useful disease predictors. (http://www.umin.ac.jp/ctr/ number, UMIN000005604).

Controlled microenvironments to evaluate chemotactic properties of cultured Müller glia

Emerging therapies have begun to evaluate the abilities of Müller glial cells (MGCs) to protect and/or regenerate neurons following retina injury. The migration of donor cells is central to many reparative strategies, where cells must achieve appropriate positioning to facilitate localized repair. Although chemical cues have been implicated in the MGC migratory responses of numerous retinopathies, MGC-based therapies have yet to explore the extent to which external biochemical stimuli can direct MGC behavior. The current study uses a microfluidics-based assay to evaluate the migration of cultured rMC-1 cells (as model MGC) in response to quantitatively-controlled microenvironments of signaling factors implicated in retinal regeneration: basic Fibroblast Growth factor (bFGF or FGF2); Fibroblast Growth factor 8 (FGF8); Vascular Endothelial Growth Factor (VEGF); and Epidermal Growth Factor (EGF). Findings indicate that rMC-1 cells exhibited minimal motility in response to FGF2, FGF8 and VEGF, but highly-directional migration in response to EGF. Further, the responses were blocked by inhibitors of EGF-R and of the MAPK signaling pathway. Significantly, microfluidics data demonstrate that changes in the EGF gradient (i.e. change in EGF concentration over distance) resulted in the directional chemotactic migration of the cells. By contrast, small increases in EGF concentration, alone, resulted in non-directional cell motility, or chemokinesis. This microfluidics-enhanced approach, incorporating the ability both to modulate and asses the responses of motile donor cells to a range of potential chemotactic stimuli, can be applied to potential donor cell populations obtained directly from human specimens, and readily expanded to incorporate drug-eluting biomaterials and combinations of desired ligands.

670nm light treatment following retinal injury modulates Müller cell gliosis: Evidence from in vivo and in vitro stress models

Photobiomodulation (PBM) with 670 nm light has been shown to accelerate wound healing in soft tissue injuries, and also to protect neuronal tissues. However, little data exist on its effects on the non-neuronal components of the retina, such as Müller cells (MCs), which are the principal macroglia of the retina that play a role in maintaining retinal homeostasis. The aim of this study was to explore the effects of 670 nm light on activated MCs using in vivo and in vitro stress models. Adult Sprague-Dawley rats were exposed to photo-oxidative damage (PD) for 24 h and treated with 670 nm light at 0, 3 and 14 days after PD. Tissue was collected at 30 days post-PD for analysis. Using the in vitro scratch model with a human MC line (MIO-M1), area coverage and cellular stress were analysed following treatment with 670 nm light. We showed that early treatment with 670 nm light after PD reduced MC activation, lowering the retinal expression of GFAP and FGF-2. 670 nm light treatment mitigated the production of MC-related pro-inflammatory cytokines (including IL-1β), and reduced microglia/macrophage (MG/MΦ) recruitment into the outer retina following PD. This subsequently decreased photoreceptor loss, slowing the progression of retinal degeneration. In vitro, we showed that 670 nm light directly modulated MC activation, reducing rates of area coverage by suppressing cellular proliferation and spreading. This study indicates that 670 nm light treatment post-injury may have therapeutic benefit when administered shortly after retinal damage, and could be useful for retinal degenerations where MC gliosis is a feature of disease progression.

Loss of Complement Factor H in Plasma Increases Endothelial Cell Migration

Tumor growth depends on angiogenesis, the growth of new blood vessels. Complement factor H (CFH) is a plasma glycoprotein that functions as a regulator of the complement system. The aim of this study is to delineate the role of CFH in angiogenesis. A conditional null allele of the Cfh gene was generated in C57BL/6J mice by flanking the exon 3 with loxP sites. The Cfh^flox/flox mice were crossed with Rosa26-Cre mice to obtain the mice homozygotes of Cfh deletion (Cfh^-/-). The Cfh^-/- mice were examined by in vivo angiogenesis assays. Mouse endothelial cells were treated with media containing 5% of mouse plasma from the wildtype or Cfh^-/- mice and assayed for proliferation, viability and migration. The Cfh^-/- mice did not display any obvious abnormalities. They demonstrated a pro-angiogenic phenotype in matrigel plug assay, but not in aorta ring assay. In vitro, loss of Cfh in plasma does not affect proliferation or viability, but significantly increases migration of mouse endothelial cells. Our findings suggest that plasma CFH inhibits angiogenesis by reduction of endothelial cell migration. Thus the mutation of CFH might lead to excessive tumor angiogenesis.

Cell number and chondrogenesis in human mesenchymal stem cell aggregates is affected by the sulfation level of heparin used as a cell coating

For particular cell-based therapies, it may be required to culture mesenchymal stem cell (MSC) aggregates with growth factors to promote cell proliferation and/or differentiation. Heparin, a negatively charged glycosaminoglycan (GAG) is known to play an important role in sequestration of positively charged growth factors and, when incorporated within cellular aggregates, could be used to promote local availability of growth factors. We have developed a heparin-based cell coating and we believe that the electrostatic interaction between native heparin and the positively charged growth factors will result in (1) higher cell number in response to fibroblast growth factor-2 (FGF-2) and 2) greater chondrogenic differentiation in response to transforming growth factor-β1 (TGF-β1), compared to a desulfated heparin coating. Results revealed that in the presence of FGF-2, by day 14, heparin-coated MSC aggregates increased in DNA content 8.5 ± 1.6 fold compared to day 1, which was greater than noncoated and desulfated heparin-coated aggregates. In contrast, when cultured in the presence of TGF-β1, by day 21, desulfated heparin-coated aggregates upregulated gene expression of collagen II by 86.5 ± 7.5 fold and collagen X by 37.1 ± 4.7 fold, which was higher than that recorded in the noncoated and heparin-coated aggregates. These observations indicate that this coating technology represents a versatile platform to design MSC culture systems with pairings of GAGs and growth factors that can be tailored to overcome specific challenges in scale-up and culture for MSC-based therapeutics. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 1817-1829, 2016.

Age-Related Macular Degeneration and Intracrine Biology: An Hypothesis

This laboratory has studied the intracellular actions of angiotensin II and other signaling proteins that can act in the intracellular space-peptides/proteins we have called intracrines. Moreover, we have suggested that general principles of intracrine action exist and can help explain the progression of some chronic degenerative diseases such as diabetic nephropathy and congestive heart failure. Here, a similar analysis is carried out in the case of age-related macular degeneration. We propose that intracrine mechanisms are operative in this disorder. In particular, we hypothesize that intracrine loops involving renin, angiotensin II, transforming growth factor-beta, vascular endothelial growth factor, bone morphogenetic protein-4, and p53, among other factors, are involved. If this analysis is correct, it suggests a commonality of mechanism linking chronic progressive renal diseases, congestive heart failure, and macular degeneration.

Mobilizing endogenous stem cells for retinal repair

Irreversible vision loss is most often caused by the loss of function and subsequent death of retinal neurons, such as photoreceptor cells-the cells that initiate vision by capturing and transducing signals of light. One reason why retinal degenerative diseases are devastating is that, once retinal neurons are lost, they don't grow back. Stem cell-based cell replacement strategy for retinal degenerative diseases are leading the way in clinical trials of transplantation therapy, and the exciting findings in both human and animal models point to the possibility of restoring vision through a cell replacement regenerative approach. A less invasive method of retinal regeneration by mobilizing endogenous stem cells is, thus, highly desirable and promising for restoring vision. Although many obstacles remain to be overcome, the field of endogenous retinal repair is progressing at a rapid pace, with encouraging results in recent years.

Transforming growth factor beta 1 induces CXCL16 and leukemia inhibitory factor expression in osteoclasts to modulate migration of osteoblast progenitors

The processes of bone resorption and bone formation are tightly coupled in young adults, which is crucial to maintenance of bone integrity. We have documented that osteoclasts secrete chemotactic agents to recruit osteoblast lineage cells, contributing to coupling. Bone formation subsequent to bone resorption becomes uncoupled with aging, resulting in significant bone loss. During bone resorption, osteoclasts release and activate transforming growth factor beta 1 (TGF-β1) from the bone matrix; thus, elevated bone resorption increases the level of active TGF-β in the local environment during aging. In this study, we examined the influences of TGF-β1 on the ability of osteoclasts to recruit osteoblasts. TGF-β1 increased osteoclast expression of the chemokine CXCL16 to promote osteoblast migration. TGF-β1 also directly stimulated osteoblast migration; however, this direct response was blocked by conditioned medium from TGF-β1-treated osteoclasts due to the presence of leukemia inhibitory factor (LIF) in the medium. CXCL16 and LIF expression was dependent on TGF-β1 activation of Smad2 and Smad3. These results establish that TGF-β1 induces CXCL16 and LIF production in osteoclasts, which modulate recruitment of osteoblasts to restore the bone lost during the resorptive phase of bone turnover.

Activated α2-macroglobulin induces Müller glial cell migration by regulating MT1-MMP activity through LRP1

In retinal proliferative diseases, Müller glial cells (MGCs) acquire migratory abilities. However, the mechanisms that regulate this migration remain poorly understood. In addition, proliferative disorders associated with enhanced activities of matrix metalloprotease 2 (MMP-2) and MMP-9 also present increased levels of the protease inhibitor α2-macroglobulin (α2M) and its receptor, the low-density lipoprotein receptor-related protein 1 (LRP1). In the present work, we investigated whether the protease activated form of α2M, α2M*, and LRP1 are involved with the MGC migratory process. By performing wound-scratch migration and zymography assays, we demonstrated that α2M* induced cell migration and proMMP-2 activation in the human Müller glial cell line, MIO-M1. This induction was blocked when LRP1 and MT1-MMP were knocked down with siRNA techniques. Using fluorescence microscopy and biochemical procedures, we found that α2M* induced an increase in LRP1 and MT1-MMP accumulation in early endosomes, followed by endocytic recycling and intracellular distribution of MT1-MMP toward cellular protrusions. Moreover, Rab11-dominant negative mutant abrogated MT1-MMP recycling pathway, cell migration, and proMMP-2 activation induced by α2M*. In conclusion, α2M*, through its receptor LRP1, induces cellular migration of Müller glial cells by a mechanism that involves MT1-MMP intracellular traffic to the plasma membrane by a Rab11-dependent recycling pathway.

TGF-beta inhibits human cutaneous melanoma cell migration and invasion through regulation of the plasminogen activator system

Over the past decades, the incidence of cutaneous melanoma in developed countries has increased faster than any other cancer. Although most patients have localized disease at the time of diagnosis and are cured by surgical excision of the primary tumor, melanoma can be highly malignant and the survival dramatically decreases for advanced stage melanomas. It is thus necessary to understand the progression of this disease. Cell migration and invasion promote tumor metastasis, the major cause of melanoma cancer morbidity and death. In this study, we investigated the role of the TGFβ/Smad signaling pathway in melanoma tumor progression and found TGFβ to potently inhibit both cell migration and invasion in human melanoma cell lines, established from different patients. Furthermore, we elucidated the molecular mechanisms by which TGFβ exerts its effects and found the plasminogen activation system (PAS) to play a central role in the regulation of these effects. We found TGFβ to strongly up-regulate the Plasminogen Activator Inhibitor-1 (PAI-1) in melanoma cells, leading to reduced plasmin generation and activity and, in turn to inhibition of cell migration and invasion. Together, our results define TGFβ as a potent suppressor of tumor progression in cutaneous melanoma, inhibiting both cell migration and invasion.