Chi-Hsien Peng

Neuroprotection by Imipramine against lipopolysaccharide-induced apoptosis in hippocampus-derived neural stem cells mediated by activation of BDNF and the MAPK pathway

Depression is accompanied by the activation of the inflammatory-response system, and increased production of proinflammatory cytokines may play a role in the pathophysiology of depressive disorders. Imipramine (IM), a tricyclic antidepressant drug, has recently been shown to promote neurogenesis and improve the survival rate of neurons in the hippocampus. However, whether IM elicits a neuroprotective or anti-inflammatory effect, or promotes the differentiation of neural stem cells (NSCs) remains to be elucidated. In this study, we cultured NSCs derived from the hippocampal tissues of adult rats as an in vitro model to evaluate the NSCs drug-modulation effects of IM. Our results showed that 3 microM IM treatment significantly increased the survival rate of NSCs, and up-regulated the mRNA and protein expression of brain-derived neurotrophic factor (BDNF) and Bcl-2 in Day-7 IM-treated NSCs. Similar to BDNF-treated effect, incubation of NSCs with 3 microM IM increased Bcl-2 protein levels and further prevented lipopolysaccharide (LPS)-induced apoptosis through the activation of the mitogen-activated protein kinase (MAPK)/extracellular-regulated kinase (ERK) pathway. Inhibition of BDNF expression with small interfering RNA (siRNA), or blocking the MAPK pathway with U0126 further significantly decreased Bcl-2 protein levels and abrogated the neuroprotective effects of IM against LPS-induced apoptosis in NSCs. In addition, the percentages of serotonin and MAP-2-positive neuronal cells in the Day 7 culture of IM-treated NSCs were significantly increased. By using microdialysis with high performance liquid chromatography-electrochemical detection, the functional release of serotonin in the process of serotoninergic differentiation of IM-treated NSCs was concomitantly increasing and mediated by the activation of the BDNF/MAPK/ERK pathway/Bcl-2 cascades. In sum, the study results indicate that IM can increase the neuroprotective effects, suppress the LPS-induced inflammatory process, and promote serotoninergic differentiation in NSCs via the modulation of the BDNF/MAPK/ERK pathway/Bcl-2 cascades.

Corneal repair by human corneal keratocyte-reprogrammed iPSCs and amphiphatic carboxymethyl-hexanoyl chitosan hydrogel

Induced pluripotent stem cells (iPSCs) have promising potential in regenerative medicine, but whether iPSCs can promote corneal reconstruction remains undetermined. In this study, we successfully reprogrammed human corneal keratocytes into iPSCs. To prevent feeder cell contamination, these iPSCs were cultured onto a serum- and feeder-free system in which they remained stable through 30 passages and showed ESC-like pluripotent property. To investigate the availability of iPSCs as bioengineered substitutes in corneal repair, we developed a thermo-gelling injectable amphiphatic carboxymethyl-hexanoyl chitosan (CHC) nanoscale hydrogel and found that such gel increased the viability and CD44+proportion of iPSCs, and maintained their stem-cell like gene expression, in the presence of culture media. Combined treatment of iPSC with CHC hydrogel (iPSC/CHC hydrogel) facilitated wound healing in surgical abrasion-injured corneas. In severe corneal damage induced by alkaline, iPSC/CHC hydrogel enhanced corneal reconstruction by downregulating oxidative stress and recruiting endogenous epithelial cells to restore corneal epithelial thickness. Therefore, we demonstrated that these human keratocyte-reprogrammed iPSCs, when combined with CHC hydrogel, can be used as a rapid delivery system to efficiently enhance corneal wound healing. In addition, iPSCs reprogrammed from corneal surgical residues may serve as an alternative cell source for personalized therapies for human corneal damage.

IV Delivery of Induced Pluripotent Stem Cells Attenuates Endotoxin-Induced Acute Lung Injury in Mice

BACKGROUND Induced pluripotent stem (iPS) cells are novel stem cell populations, but the role of iPS cells in acute lung injury (ALI) is not currently known. We investigated the effect of iPS cells in modifying the pathophysiology of endotoxin-induced ALI. METHODS Male C57BL/6 8- to 12-week-old mice were enrolled in this study. Mouse iPS cells were delivered through the tail veins of mice 4 h after intratracheal instillation of endotoxin. Lung histopathologic findings, the pulmonary levels of cytokines, and functional parameters were analyzed after either 24 h or 48 h. RESULTS More iPS cells integrated into the lungs of mice with ALI than those of the control mice, as demonstrated by in vivo radionuclide imaging and in vitro Hoechst-labeled fluorescent staining. iPS cells significantly diminished the histopathologic changes of ALI and the lung injury score. There was also a significant reduction in the activity of nuclear factor-κB (NF-κB) and neutrophil accumulation in the lung, confirmed by immunostaining, electrophoretic mobility shift assays, and the decrease of myeloperoxidase activity, in the iPS-cell-treated mice with ALI. These protective effects were not replicated by the control cell therapy with fibroblasts. iPS cells mediated a downregulation of the proinflammatory response to endotoxin (reducing tumor necrosis factor-α, IL-6, and macrophage inflammatory peptide-2). In addition, iPS cells rescued the hypoxemia and pulmonary function of ALI. Treatment with a conditioned medium of iPS cells showed effects similar to those of iPS cells, which may suggest the therapeutic benefits of iPS mediated by paracrine factors. CONCLUSIONS IV delivery of iPS cells provides a beneficial effect to attenuate the severity of endotoxin-induced ALI and improve physiologic impairment, which is partly mediated by a reduction in NF-κB activity and neutrophils accumulation. The conditioned medium of iPS cells demonstrated effects equal to those of iPS cells.

A novel in vitro retinal differentiation model by co-culturing adult human bone marrow stem cells with retinal pigmented epithelium cells

Human retinal pigment epithelium (HRPE) cells are important in maintaining the normal physiology within the neurosensory retina and photoreceptors. Recently, transplantation of HRPE has become a possible therapeutic approach for retinal degeneration. By negative immunoselection (CD45 and glycophorin A), in this study, we have isolated and cultivated adult human bone marrow stem cells (BMSCs) with multilineage differentiation potential. After a 2- to 4-week culture under chondrogenic, osteogenic, adipogenic, and hepatogenic induction medium, these BMSCs were found to differentiate into cartilage, bone, adipocyte, and hepatocyte-like cells, respectively. We also showed that these BMSCs could differentiate into neural precursor cells (nestin-positive) and mature neurons (MAP-2 and Tuj1-positive) following treatment of neural selection and induction medium for 1 month. Furthermore, the plasticity of BMSCs was confirmed by initiating their differentiation into retinal cells and photoreceptor lineages by co-culturing with HRPE cells. The latter system provides an ex vivo expansion model of culturing photoreceptors for the treatment of retinal degeneration diseases.

One-year outcomes of intravitreal bevacizumab (avastin) therapy for polypoidal choroidal vasculopathy.

Purpose: To report on 1-year visual, anatomical, and angiographic responses with intravitreal bevacizumab for the treatment of polypoidal choroidal vasculopathy. Methods: Patients with macula-involved, symptomatic polypoidal choroidal vasculopathy with initial best-corrected visual acuity of 20/400 or better and a minimal follow-up period of 12 months were retrospectively enrolled. Eyes were treated with intravitreal bevacizumab (2.5 mg) at baseline and monitored monthly for best-corrected visual acuity and central retinal thickness (by optical coherence tomography). Indocyanine green angiography was evaluated on a 6-month basis. Eyes were retreated on an “as-needed” basis according to visual and anatomical changes. Results: A total of 35 eyes of 33 patients were treated with a mean of 3.3 (range, 1-8) times of injection. Best-corrected visual acuity significantly improved from a mean logarithm of the minimum angle of resolution of 0.79 ± 0.42 at baseline (Snellen equivalent, 20/123) to 0.69 ± 0.47 (20/94), 0.66 ± 0.45 (20/87), 0.67 ± 0.44 (20/87), 0.67 ± 0.48 (20/87), and 0.67 ± 0.51 (20/87) at 1, 3, 6, 9, and 12 months, respectively (P = 0.002, 0.0003, 0.0008, 0.017, and 0.02, respectively; paired Students t-test). Central retinal thickness also significantly improved from a mean of 297 ± 94 μm at baseline to 215 ± 58 μm, 214 ± 59 μm, 218 ± 79 μm, 213 ± 75 μm, and 221 ± 61 μm at 1, 3, 6, 9, and 12 months, respectively (all P < 0.0001, paired Students t-test). Indocyanine green angiography showed 3 of 32 eyes (9.4%) and 5 of 31 eyes (16.1%) with completely resolved polyps and 11 of 32 eyes (34.4%) and 10 of 31 eyes (32.3%) with reduced polyps at 6 and 12 months, respectively. No systemic complication or severe local complication, such as endophthalmitis, was found. Conclusion: Intravitreal bevacizumab therapy has a favorable outcome in improving visual acuity and macular exudative changes in patients with polypoidal choroidal vasculopathy. It can also moderately reduce polypoidal lesions on indocyanine green angiography.

Possible Involvement of Nitric Oxide in the Progression of Diabetic Retinopathy

Abnormal nitric oxide (NO) synthesis has been implicated in the pathogenesis of diabetes mellitus. The aim of our study was to elucidate the relationship between the stages of diabetic retinopathy (DR) and the NO levels in aqueous humor and plasma. Using the chemiluminescence assay, we measured the concentrations of NO in aqueous humor and plasma samples obtained during intraocular surgery from 45 diabetic patients and 19 nondiabetic cataract patients. The patients with diabetes were classified into 4 groups: proliferative DR (PDR) with active neovascularization (active PDR; 9 cases), PDR with quiescent neovascularization (regressed PDR; 6 cases), background DR (BDR; 16 cases) and no DR (14 cases). We found that the aqueous NO levels (mean ± SE) of the active PDR group (83.2 ± 13.9 µM) were significantly higher than those of the BDR group (45.8 ± 6.0 µM, p = 0.049) and the diabetics without DR (33.3 ± 5.2 µM, p = 0.011), and, although not statistically significantly, they were also higher than those of the regressed PDR group (52.1 ± 10.3 µM, p = 0.224). However, no significant differences were observed between any of the diabetic subgroups in the plasma NO levels (p = 0.345). We therefore concluded that NO present in the ocular tissues may play important roles in the progression of DR.

Delivery of Oct4 and SirT1 with cationic polyurethanes-short branch PEI to aged retinal pigment epithelium

Cationic polyurethane, a biodegradable non-viral vector, protects DNA from nuclease degradation and helps to deliver genes efficiently. Oct4, a POU-domain transcription factor, is highly expressed in maintaining pluripotency and cellular reprogramming process in stem cells. SirT1, a NAD-dependent histone deacetylase, is an essential mediator of cellular longevity. Herein we demonstrated that both Oct4 and SirT1 (Oct4/SirT1) expression was decreased in an age-dependent manner in retina with aged-related macular degeneration and retinal pigment epithelium cells (RPEs). To investigate the possible rescuing role of Oct4/SirT1, polyurethane-short branch polyethylenimine (PU-PEI) was used to deliver Oct4/SirT1 into aged RPEs (aRPEs) or light-injured rat retinas. Oct4/SirT1 overexpression increased the expression of several progenitor-related genes and the self-renewal ability of aRPEs. Moreover, Oct4/SirT1 overexpression resulted in the demethylation of the Oct4 promoter and enhanced the expression of antioxidant enzymes, which was accompanied by a decrease in intracellular ROS production and hydrogen peroxide-induced oxidative stress. Importantly, PU-PEI-mediated Oct4/SirT1 gene transfer rescued retinal cell loss and improved electroretinographic responses in light-injured rat retinas. In summary, these data suggest that PU-PEI-mediated delivery of Oct4/SirT1 reprograms aRPEs into a more primitive state and results in cytoprotection by regulating the antioxidative capabilities of these cells.

Significant Variation of the Elevated Nitric Oxide Levels in Aqueous Humor from Patients with Different Types of Glaucoma

Though several studies have shown that the biochemical function of nitric oxide (NO) in the eye might play an important role in the regulation of intraocular pressure (IOP), local control of ocular blood flow and loss of retinal ganglion cells by apoptosis, it is unclear whether the role of NO is similar in the pathogenesis of different kinds of glaucoma: primary open-angle glaucoma (POAG), chronic closed-angle glaucoma (CCAG) and neovascular glaucoma (NVG). To further explore this issue, we measured the concentrations of NO in aqueous humor and plasma samples from patients with POAG (n = 31), CCAG (n = 76), NVG (n = 8) and cataract (n = 30). All of the NVG patients suffered from severe proliferative diabetic retinopathy, while other patients were free of any other systemic disease. The NO levels in both aqueous humor and plasma samples were assessed by chemiluminescence assay. We found that the NO levels in aqueous humor samples were greatly varied in patients with POAG (36.2 ± 3.3 µM), CCAG (47.7 ± 3.4 µM) and NVG (65.8 ± 5.4 µM), and all of them were significantly higher than in cataract patients (27.0 ± 2.9 µM; p < 0.05). Except NVG patients whose NO levels in plasma samples were highest (24.1 ± 3.5 µM) among all groups, the plasma NO levels were not significantly different between the other glaucoma patients and the cataract patients. We therefore concluded that significant variation of the elevated NO levels in aqueous humor samples from the patients with different types of glaucoma may reflect their differences in the pathogenesis.

MicroRNAs and cataracts: correlation among let-7 expression, age and the severity of lens opacity

Background Let-7 microRNA is an important regulator of cellular ageing and tissue senescence. The objective of this study is to evaluate the expression of let-7a/let-7b/let-7c microRNAs in human age-related cataracts. Aim To evaluate the correlation among the severity of lens opacity, the level of let-7a/let-7b/let-7c microRNA expression and patient age in the context of age-related cataracts. Methods The authors evaluated the mRNA level of let-7a/let-7b/let-7c microRNA in lens epithelia obtained from 174 eyes with age-related cataracts. The authors also recorded the patient age and the severity of lens opacity as classified according to the modified version of the Lens Opacities Classification System version III. Results Let-7b microRNA expression was demonstrated to be positively associated with patient age (R=0.472; p<0.001). A positive correlation was also observed between higher N, C and P cataract scores and higher expression of let-7b microRNA in patients with age-related cataracts (p<0.001). However, no significant correlation was observed between the let-7a and let-7c microRNA expression levels and either the severity of lens opacity or the patient age. Conclusion These findings suggest that microRNAs play a role in age-related cataracts. A local let-7b microRNA increase may represent a risk factor in the formation of age-related cataracts.

Enhanced Antioxidant Capacity of Dental Pulp-Derived iPSC-Differentiated Hepatocytes and Liver Regeneration by Injectable HGF-Releasing Hydrogel in Fulminant Hepatic Failure

Acute hepatic failure (AHF) is a severe liver injury leading to sustained damage and complications. Induced pluripotent stem cells (iPSCs) may be an alternative option for the treatment of AHF. In this study, we reprogrammed human dental pulp-derived fibroblasts into iPSCs, which exhibited pluripotency and the capacity to differentiate into tridermal lineages, including hepatocyte-like cells (iPSC-Heps). These iPSC-Heps resembled human embryonic stem cell-derived hepatocyte-like cells in gene signature and hepatic markers/functions. To improve iPSC-Heps engraftment, we next developed an injectable carboxymethyl-hexanoyl chitosan hydrogel (CHC) with sustained hepatocyte growth factor (HGF) release (HGF-CHC) and investigated the hepatoprotective activity of HGF-CHC-delivered iPSC-Heps in vitro and in an immunocompromised AHF mouse model induced by thioacetamide (TAA). Intrahepatic delivery of HGF-CHC-iPSC-Heps reduced the TAA-induced hepatic necrotic area and rescued liver function and recipient viability. Compared with PBS-delivered iPSC-Heps, the HGF-CHC-delivered iPSC-Heps exhibited higher antioxidant and antiapoptotic activities that reduced hepatic necrotic area. Importantly, these HGF-CHC-mediated responses could be abolished by administering anti-HGF neutralizing antibodies. In conclusion, our findings demonstrated that HGF mediated the enhancement of iPSC-Hep antioxidant/antiapoptotic capacities and hepatoprotection and that HGF-CHC is as an excellent vehicle for iPSC-Hep engraftment in iPSC-based therapy against AHF.