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Todd C. Mcdevitt - One of the best experts on this subject based on the ideXlab platform.

  • Microfluidic perfusion modulates growth and motor neuron differentiation of stem Cell Aggregates.
    The Analyst, 2020
    Co-Authors: Emily Jackson-holmes, Amanda W. Schaefer, Todd C. Mcdevitt
    Abstract:

    Microfluidic technologies provide many advantages for studying differentiation of three-dimensional (3D) stem Cell Aggregates, including the ability to control the culture microenvironment, isolate individual Aggregates for longitudinal tracking, and perform imaging-based assays. However, applying microfluidics to studying mechanisms of stem Cell differentiation requires an understanding of how microfluidic culture conditions impact Cell phenotypes. Conventional Cell culture techniques cannot directly be applied to the microscale, as microscale culture varies from macroscale culture in multiple aspects. Therefore, the objective of this work was to explore key parameters in microfluidic culture of 3D stem Cell Aggregates and to understand how these parameters influence stem Cell behavior and differentiation. These studies were done in the context of differentiation of embryonic stem Cells (ESCs) to motor neurons (MNs). We assessed how media exchange frequency modulates the biochemical microenvironment, including availability of exogenous factors (e.g. nutrients, small molecule additives) and Cell-secreted molecules, and thereby impacts differentiation. The results of these studies provide guidance on how key characteristics of 3D Cell cultures can be considered when designing microfluidic culture parameters. We demonstrate that discontinuous perfusion is effective at supporting stem Cell aggregate growth. We find that there is a balance between the frequency of media exchange, which is needed to ensure that Cells are not nutrient-limited, and the need to allow accumulation of Cell-secreted factors to promote differentiation. Finally, we show how microfluidic device geometries can influence transport of biomolecules and potentially promote asymmetric spatial differentiation. These findings are instructive for future work in designing devices and experiments for culture of Cell Aggregates.

  • a microfluidic trap array for longitudinal monitoring and multi modal phenotypic analysis of individual stem Cell Aggregates
    Lab on a Chip, 2017
    Co-Authors: Emily Jacksonholmes, Todd C. Mcdevitt
    Abstract:

    Three-dimensional pluripotent stem Cell (PSC) cultures have the ability to undergo differentiation, self-organization, and morphogenesis to yield complex, in vitro tissue models that recapitulate key elements of native tissues. These tissue models offer a system for studying mechanisms of tissue development, investigating disease mechanisms, and performing drug screening. It remains challenging, however, to standardize PSC aggregate differentiation and morphogenesis methods due to heterogeneity stemming from biological and environmental sources. It is also difficult to monitor and assess large numbers of individual samples longitudinally throughout culture using typical batch-based culture methods. To address these challenges, we have developed a microfluidic platform for culture, longitudinal monitoring, and phenotypic analysis of individual stem Cell Aggregates. This platform uses a hydrodynamic loading principle to capture pre-formed stem Cell Aggregates in independent traps. We demonstrated that multi-day culture of Aggregates in this platform reduces heterogeneity in phenotypic parameters such as size and morphology. Additionally, we showed that culture and analysis steps can be performed sequentially in the same platform, enabling correlation of multiple modes of analysis for individual samples. We anticipate this platform being applied to improve abilities for phenotypic analysis of PSC aggregate tissues and to facilitate research in standardizing culture systems in order to dually increase the yield and reduce the heterogeneity of PSC-derived tissues.

  • mineral particles modulate osteo chondrogenic differentiation of embryonic stem Cell Aggregates
    Acta Biomaterialia, 2016
    Co-Authors: Yun Wang, William L. Murphy, Todd C. Mcdevitt, Christopher Baker
    Abstract:

    Abstract Pluripotent stem Cell Aggregates offer an attractive approach to emulate embryonic morphogenesis and skeletal development. Calcium phosphate (CaP) based biomaterials have been shown to promote bone healing due to their osteoconductive and potential osteoinductive properties. In this study, we hypothesized that incorporation of CaP-coated hydroxyapatite mineral particles (MPs) within murine embryonic stem Cell (ESC) Aggregates could promote osteo-chondrogenic differentiation. Our results demonstrated that MP alone dose-dependently promoted the gene expression of chondrogenic and early osteogenic markers. In combination with soluble osteoinductive cues, MPs enhanced the hypertrophic and osteogenic phenotype, and mineralization of ESC Aggregates. Additionally, MPs dose-dependently reduced ESC pluripotency and thereby decreased the size of teratomas derived from MP-incorporated ESC Aggregates in vivo . Our data suggested a novel yet simple means of using mineral particles to control stem Cell fate and create an osteochondral niche for skeletal tissue engineering applications. Statement of Significance Directing stem Cell differentiation and morphogenesis via biomaterials represents a novel strategy to promote Cell fates and tissue formation. Our study demonstrates the ability of calcium phosphate-based mineral particles to promote osteochondrogenic differentiation of embryonic stem Cell Aggregates as well as modulate teratoma formation in vivo . This hybrid biomaterial–ESC aggregate approach serves as an enabling platform to evaluate the ability of biomaterials to regulate stem Cell fate and regenerate functional skeletal tissues for clinical applications.

  • a microparticle approach to morphogen delivery within pluripotent stem Cell Aggregates
    Biomaterials, 2013
    Co-Authors: Andres M Brattleal, Todd C. Mcdevitt, Anh Nguyen, Katy A Hammersmith, Ankur Singh
    Abstract:

    Stem Cell fate and specification is largely controlled by extrinsic cues that comprise the 3D microenvironment. Biomaterials can serve to control the spatial and temporal presentation of morphogenic molecules in order to direct stem Cell fate decisions. Here we describe a microparticle (MP)-based approach to deliver growth factors within multiCellular Aggregates to direct pluripotent stem Cell differentiation. Compared to conventional soluble delivery methods, gelatin MPs laden with BMP4 or noggin induced efficient gene expression of mesoderm and ectoderm lineages, respectively, despite using nearly 12-fold less total growth factor. BMP4-laden MPs increased the percentage of Cells expressing GFP under the control of the Brachyury-T promoter as visualized by whole-mount confocal imaging and quantified by flow cytometry. Furthermore, the ability to localize MPs laden with different morphogens within a particular hemisphere of stem Cell Aggregates allowed for spatial control of differentiation within 3D cultures. Overall, localized delivery of growth factors within multiCellular Aggregates from microparticle delivery vehicles is an important step towards scalable differentiation technologies and the study of morphogen gradients in pluripotent stem Cell differentiation.

William L. Murphy - One of the best experts on this subject based on the ideXlab platform.

  • Controlled Self-assembly of Stem Cell Aggregates Instructs Pluripotency and Lineage Bias.
    Scientific reports, 2017
    Co-Authors: Angela W. Xie, Bernard Y.k. Binder, Andrew S. Khalil, Samantha K. Schmitt, Hunter J. Johnson, Nicholas A. Zacharias, William L. Murphy
    Abstract:

    Stem Cell-derived organoids and other 3D microtissues offer enormous potential as models for drug screening, disease modeling, and regenerative medicine. Formation of stem/progenitor Cell Aggregates is common in biomanufacturing processes and critical to many organoid approaches. However, reproducibility of current protocols is limited by reliance on poorly controlled processes (e.g., spontaneous aggregation). Little is known about the effects of aggregation parameters on Cell behavior, which may have implications for the production of Cell Aggregates and organoids. Here we introduce a bioengineered platform of labile substrate arrays that enable simple, scalable generation of Cell Aggregates via a controllable 2D-to-3D “self-assembly”. As a proof-of-concept, we show that labile substrates generate size- and shape-controlled embryoid bodies (EBs) and can be easily modified to control EB self-assembly kinetics. We show that aggregation method instructs EB lineage bias, with faster aggregation promoting pluripotency loss and ectoderm, and slower aggregation favoring mesoderm and endoderm. We also find that aggregation kinetics of EBs markedly influence EB structure, with slower kinetics resulting in increased EB porosity and growth factor signaling. Our findings suggest that controlling internal structure of Cell Aggregates by modifying aggregation kinetics is a potential strategy for improving 3D microtissue models for research and translational applications.

  • mineral particles modulate osteo chondrogenic differentiation of embryonic stem Cell Aggregates
    Acta Biomaterialia, 2016
    Co-Authors: Yun Wang, William L. Murphy, Todd C. Mcdevitt, Christopher Baker
    Abstract:

    Abstract Pluripotent stem Cell Aggregates offer an attractive approach to emulate embryonic morphogenesis and skeletal development. Calcium phosphate (CaP) based biomaterials have been shown to promote bone healing due to their osteoconductive and potential osteoinductive properties. In this study, we hypothesized that incorporation of CaP-coated hydroxyapatite mineral particles (MPs) within murine embryonic stem Cell (ESC) Aggregates could promote osteo-chondrogenic differentiation. Our results demonstrated that MP alone dose-dependently promoted the gene expression of chondrogenic and early osteogenic markers. In combination with soluble osteoinductive cues, MPs enhanced the hypertrophic and osteogenic phenotype, and mineralization of ESC Aggregates. Additionally, MPs dose-dependently reduced ESC pluripotency and thereby decreased the size of teratomas derived from MP-incorporated ESC Aggregates in vivo . Our data suggested a novel yet simple means of using mineral particles to control stem Cell fate and create an osteochondral niche for skeletal tissue engineering applications. Statement of Significance Directing stem Cell differentiation and morphogenesis via biomaterials represents a novel strategy to promote Cell fates and tissue formation. Our study demonstrates the ability of calcium phosphate-based mineral particles to promote osteochondrogenic differentiation of embryonic stem Cell Aggregates as well as modulate teratoma formation in vivo . This hybrid biomaterial–ESC aggregate approach serves as an enabling platform to evaluate the ability of biomaterials to regulate stem Cell fate and regenerate functional skeletal tissues for clinical applications.

Stavroula Balabani - One of the best experts on this subject based on the ideXlab platform.

  • Partitioning of red blood Cell Aggregates in bifurcating microscale flows.
    Scientific reports, 2017
    Co-Authors: Efstathios Kaliviotis, Joseph M. Sherwood, Stavroula Balabani
    Abstract:

    Microvascular flows are often considered to be free of red blood Cell Aggregates, however, recent studies have demonstrated that Aggregates are present throughout the microvasculature, affecting Cell distribution and blood perfusion. This work reports on the spatial distribution of red blood Cell Aggregates in a T-shaped bifurcation on the scale of a large microvessel. Non-aggregating and aggregating human red blood Cell suspensions were studied for a range of flow splits in the daughter branches of the bifurcation. Aggregate sizes were determined using image processing. The mean aggregate size was marginally increased in the daughter branches for a range of flow rates, mainly due to the lower shear conditions and the close Cell and aggregate proximity therein. A counterintuitive decrease in the mean aggregate size was apparent in the lower flow rate branches. This was attributed to the existence of regions depleted by Aggregates of certain sizes in the parent branch, and to the change in the exact flow split location in the T-junction with flow ratio. The findings of the present investigation may have significant implications for microvascular flows and may help explain why the effects of physiological RBC aggregation are not deleterious in terms of in vivo vascular resistance.

Kai P Leung - One of the best experts on this subject based on the ideXlab platform.

  • In vitro characterization of scaffold-free three-dimensional mesenchymal stem Cell Aggregates
    Cell and Tissue Research, 2014
    Co-Authors: Christina L. Rettinger, Andrea B. Fourcaudot, Robert G. Hale, Seok J. Hong, Thomas A. Mustoe, Kai P Leung
    Abstract:

    Mesenchymal stem Cells (MSCs) are capable of self-renewal and differentiation along multiple Cell lineages and have potential applications in a wide range of therapies. These Cells are commonly cultured as monolayers on tissue culture plastic but possibly lose their Cell-specific properties with time in vitro. There is growing interest in culturing adherent Cells via three-dimensional (3D) techniques in order to recapitulate 3D in vivo conditions. We describe a novel method for generating and culturing rabbit MSCs as scaffold-free 3D Cell Aggregates by using micropatterned wells via a forced aggregation technique. The viability and proliferative capability of MSC Aggregates were assessed via Live/Dead staining and 5-ethynyl-2'-deoxyuridine (EdU) incorporation. Enzyme-linked immunosorbent assay and antibody-based multiplex protein assays were used to quantify released growth factors and chemokines. The gene expression profile of MSCs as 3D Aggregates relative to MSCs grown as monolayers was evaluated via quantitative real-time polymerase chain reaction. The rabbit MSCs were able to form compact Cell Aggregates and remained viable in 3D culture for up to 7 days. We also demonstrated enhanced gene and protein expression related to angiogenesis and wound healing in MSCs cultured under 3D conditions. In vitro tube formation and scratch assay revealed superior neovessel formation and greater Cell recovery and migration in response to 3D conditioned media after wounding. Our data further suggest that adipose-derived stem Cell Aggregates have greater potential than dermal fibroblasts or bone-marrow-derived MSCs in accelerating wound healing and reducing scarring.

Carl Denef - One of the best experts on this subject based on the ideXlab platform.