High Throughput Characterization of Adult Stem Cells Engineered for Delivery of Therapeutic Factors for Neuroprotective Strategies

Mesenchymal stem cells (MSCs) derived from bone marrow are a powerful cellular resource and have been used in numerous studies as potential candidates to ...

Iowa State University

The neuronal localization of alpha-amino-3-hydroxyl-5-methyl-4-isoxazole propionic acid (AMPA) glutamate receptor (GluR) subunits is vital as they play key roles in the regulation of calcium permeability. We have examined the distribution of the calcium permeable AMPA glutamate receptor subunit GluR1 in the mouse visual cortex immunocytochemically. We compared this distribution to that of the calcium-binding proteins calbindin D28K, calretinin, and parvalbumin, and of GABA. The highest density of GluR1-immunoreactive (IR) neurons was found in layers II/III. Enucleation appeared to have no effect on the distribution of GluR1-IR neurons. The labeled neurons varied in morphology; the majority were round or oval and no pyramidal cells were labeled by the antibody. Two-color immunofluorescence revealed that 26.27%, 10.65%, and 40.31% of the GluR1-IR cells also contained, respectively, calbindin D28K, calretinin, and parvalbumin. 20.74% of the GluR1-IR neurons also expressed GABA. These results indicate that many neurons that express calcium-permeable GluR1 also express calcium binding proteins. They also demonstrate that one fifth of the GluR1-IR neurons in the mouse visual cortex are GABAergic interneurons.

Distribution of AMPA glutamate receptor GluR1 subunit-immunoreactive neurons and their co-localization with calcium-binding proteins and GABA in the mouse visual cortex.

The subunit composition of the AMPA receptor is critical to its function. AMPA receptors that display very low calcium permeability include the GluR2 subunit, while AMPA receptors that contain other subunits, such as GluR1, display high calcium permeability. We have studied the distribution and morphology of neurons containing GluR1 in the hamster visual cortex with antibody immunocytochemistry. We compared this labeling to that for calbindin D28K, parvalbumin, and GABA. Anti-GluR1-immunoreactive (IR) neurons were located in all layers. The highest density of GluR1-IR neurons was found in layers II/III. The labeled neurons were non-pyramidal neurons, but were varied in morphology. The majority of the labeled neurons were round or oval cells. However, stellate, vertical fusiform, pyriform, and horizontal neurons were also labeled with the anti-GluR1 antibody. Two-color immunofluorescence revealed that many of the GluR1-IR neurons in the hamster visual cortex were double-labeled with either calbindin D28K (31.50%), or parvalbumin (22.91%), or GABA (63.89%). These results indicate that neurons in the hamster visual cortex express GluR1 differently according to different layers and selective cell types, and that many of the GluR1-IR neurons are limited to neurons that express calbindin D28K, parvalbumin, or GABA. The present study elucidates the neurochemical structure of GluR1, a useful clue in understanding the differential vulnerability of GluR1-containing neurons with regard to calcium-dependent excitotoxic mechanisms.

Ionotropic glutamate receptor GluR1 in the visual cortex of hamster: distribution and co-localization with calcium-binding proteins and GABA.

We localized calbindin D28K-immunoreactive (IR) neurons in the superior colliculus (SC) of the dog and studied the distribution and effect of enucleation on the distribution of this protein. We also compared this labeling to that of GABA. Calbindin D28K was localized with antibody immunocytochemistry. Calbindin D28K-IR neurons formed three laminar tiers in the SC, one within the lower superficial gray layer (SGL), the second within the upper intermediate gray layers (IGL), and the third within the deep gray layer (DGL). The third tier was not very distinctive when compared with the other two tiers. Calbindin D28K-IR neurons in the SC varied dramatically in morphology and size, and included round/oval, vertical fusiform, stellate, pyriform, and horizontal neurons. Neurons with varicose dendrite were also labeled in the IGL. Enucleation appeared to have no effect on the distribution of calbindin D28K-IR neurons in the contralateral SC. Two-color immunofluorescence revealed that a small percentage (11.20%) of calbindin D28K-IR neurons co-localized with GABA. The current results demonstrate that the patterned distribution of calbindin D28K-IR neurons in the intermediate and deep SC is comparable with other animals, but that the distribution of this protein in the superficial SC is strikingly different from that in previously studied animals. The results also suggest that retinal projection may not control the activity of the expression of calbindin D28K in the dog SC. These results will not only provide valuable knowledge of the basic neurochemical architecture of the dog visual system, but also provide clues for the understanding of the similarities and differences among species.

Organization of calbindin D28K-immunoreactive neurons in the dog superior colliculus.

Adult rat hippocampal progenitor cells (AHPCs) are self-renewing, multipotent neural progenitor cells (NPCs) that can differentiate into neurons, oligodendrocytes, and astrocytes. AHPCs contact a variety of molecular cues within their surrounding microenvironment via integrins. We hypothesize that integrin receptors are important for NPCs. In this study, we have examined the distribution of integrins in neuronal-like, oligodendrocyte-like, and astrocyte-like AHPCs when grown on substrates that support integrin-mediated adhesion (laminin, fibronectin), and those that do not (poly-L: -ornithine, PLO) using immunocytochemistry as well as characterized the phenotypic differentiation of AHPCs plated on laminin and fibronectin. Focal adhesions were prominent in AHPCs plated on purified substrates, but were also found in AHPCs plated on PLO. The focal adhesions observed in AHPCs plated on PLO substrates may be formed by self-adhesion to the endogenously produced laminin or fibronectin. We have demonstrated that integrins contribute to the initial morphological differentiation of AHPCs, as inhibition of fibronectin binding with the competitive inhibitor echistatin significantly decreased the number of processes and microspikes present in treated cells, and also decreased overall cell area. Finally, we have characterized the genetic profile of a subset of integrins and integrin-related genes in the AHPCs using reverse transcriptase polymerase chain reaction. These results demonstrate an important role of integrins, in vitro, for the initial morphological differentiation of AHPCs.

Integrins contribute to initial morphological development and process outgrowth in rat adult hippocampal progenitor cells.

In this study we investigated the differentiation of human neural progenitor cells (hNPCs) in vitro to evaluate their differentiation potential and in vivo to explore their viability and behavior following transplantation. Progenitors were maintained as neurospheres in media containing basic fibroblast growth factor and epidermal growth factor. Micropatterned polystyrene substrates were fabricated and coated with ECL (entactin, collagen, and laminin) to provide physical and chemical guidance during the differentiation of the hNPCs. The hNPCs growing on the micropatterned substrates showed no differences in proliferation or differentiation potential compared with those hNPCs growing on the nonpatterned substrates. However, hNPCs cultured on the micropatterned substrates were aligned in the direction of the micropattern compared with those cells growing on the nonpatterned substrates. Furthermore, hNPC migration was directed in alignment with the micropatterned substrates. Transplantation of the hNPCs into the developing retina was used to evaluate their behavior in vivo. Cells displayed extensive survival, differentiation, and morphological integration following xenotransplant into the retina, even in the absence of immunosuppression. Taken together, our results show that these multipotent hNPCs are a neurogenic progenitor population that can be maintained in culture for extended periods. Although the micropatterned substrates have no major effect on the proliferation or differentiation of the hNPCs, they clearly promoted alignment and directed neurite outgrowth along the pattern as well as directing migration of the cells. These approaches may provide important strategies to guide the growth and differentiation of NPCs in vitro and in vivo.

Differentiation and behavior of human neural progenitors on micropatterned substrates and in the developing retina.

To perform in vivo analysis of retinal functional and structural parameters in healthy mouse eyes.

Characterization of structure and function of the mouse retina using pattern electroretinography, pupil light reflex, and optical coherence tomography.

Adult hippocampal progenitor cells (AHPCs) are generally maintained as a dispersed monolayer population of multipotent neural progenitors. To better understand cell-cell interactions among neural progenitors and their influences on cellular characteristics, we generated free-floating cellular aggregates, or neurospheres, from the adherent monolayer population of AHPCs. Results from in vitro analyses demonstrated that both populations of AHPCs were highly proliferative under maintenance conditions, but AHPCs formed in neurospheres favored differentiation along a glial lineage and displayed greater migrational activity than the traditionally cultured AHPCs. To study the plasticity of AHPCs from both populations in vivo, we transplanted green fluorescent protein (GFP)-expressing AHPCs via intraocular injection into the developing rat eyes. Both AHPC populations were capable of surviving and integrating into developing host central nervous system, but considerably more GFP-positive cells were observed in the retinas transplanted with neurosphere AHPCs, compared to adherent AHPCs. These results suggest that the culture configuration during maintenance for neural progenitor cells (NPCs) influences cell fate and motility in vitro as well as in vivo. Our findings have implication for understanding different cellular characteristics of NPCs according to distinct intercellular architectures and for developing cell-based therapeutic strategies using lineage-committed NPCs.

Multipotent adult hippocampal progenitor cells maintained as neurospheres favor differentiation toward glial lineages.

Determine whether Compound 49b treatment ameliorates retinal changes due to the lack of β2-adrenergic receptor signaling.

β1-adrenergic receptor stimulation by agonist Compound 49b restores insulin receptor signal transduction in vivo.

Dysfunctional insulin signaling is a key component of type 2 diabetes. Little is understood of the effects of systemic diabetes on retinal insulin signaling. A number of agents are used to treat patients with type 2 diabetes to normalize glucose levels and improve insulin signaling; however, little has been done to investigate the effects of these agents on retinal insulin signal transduction. We hypothesized that pioglitazone, a peroxisome proliferator-activated receptor γ (PPARγ) agonist, would normalize retinal insulin signal transduction through reduced tumor necrosis factor α (TNFα) and suppressor of cytokine signaling 3 (SOCS3) activities in whole retina and retinal endothelial cells (REC) and Müller cells. To test this hypothesis, we used the BBZDR/Wor type 2 diabetic rat model, as well as REC and Müller cells cultured in normoglycemia and hyperglycemic conditions, to investigate the effects of pioglitazone on TNFα, SOCS3, and downstream insulin signal transduction proteins. We also evaluated pioglitazone's effects on retinal function using electroretinogram and markers of apoptosis. Data demonstrate that 2 months of pioglitazone significantly increased electroretinogram amplitudes in type 2 diabetic obese rats, which was associated with improved insulin receptor activation. These changes occurred in both REC and Müller cells treated with pioglitazone, suggesting that these two cell types are key to insulin resistance in the retina. Taken together, these data provide evidence of impaired insulin signaling in type 2 diabetes rats, which was improved by increasing PPARγ activity. Further investigations of PPARγ actions in the retina may provide improved treatment options.

Pioglitazone normalizes insulin signaling in the diabetic rat retina through reduction in tumor necrosis factor α and suppressor of cytokine signaling 3.

Inhibition of TNFα protects the retina against diabetic-like changes in rodent models. The mechanism by which TNFα induces deleterious retinal changes is not known. Previously, we have shown that TNFα can inhibit normal insulin signal transduction, leading to increased apoptosis in both retinal endothelial cells (REC) and Müller cells. Additionally, β2-adrenergic receptor knockout mice (β2KO) have increased TNFα levels and decreased insulin receptor activity. In this study, we hypothesized that inhibition of TNFα in β2KO mice would increase normal insulin signaling, leading to improved retinal function.

Eun-Ah Ye

Department of Genetics,
Development and Cell Biology,
Department of Genetics, Development and Cell Biology

Iowa State University

High Throughput Characterization of Adult Stem Cells Engineered for Delivery of Therapeutic Factors for Neuroprotective Strategies

Eun-Ah Ye

.css-o250i3{font-size:18px;font-family:Open Sans,sans-serif;line-height:21.6px;}Department of Genetics,Development and Cell Biology,Department of Genetics, Development and Cell Biology

Iowa State University

High Throughput Characterization of Adult Stem Cells Engineered for Delivery of Therapeutic Factors for Neuroprotective Strategies

Department of Genetics,
Development and Cell Biology,
Department of Genetics, Development and Cell Biology