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Title:Exploring nanoparticles' interactions with blood proteins and visualizing the heterogeneity within hematopoietic cell populations
Author(s):Mirshafiee, Vahid
Director of Research:Kraft, Mary L.
Doctoral Committee Chair(s):Kraft, Mary L.
Doctoral Committee Member(s):Murphy, Catherine J.; Kong, Hyunjoon; Yang, Hong
Department / Program:Chemical & Biomolecular Engr
Discipline:Chemical Engineering
Degree Granting Institution:University of Illinois at Urbana-Champaign
Protein Corona
Hematopoietic Cells
Abstract:Nanoparticles (NPs) functionalized with targeting ligands are expected to improve the yield of targeted drug delivery by recognizing target cells and selectively delivering the therapeutic drugs to these cells. However, functionalized-NPs often have low targeting efficiency when they are administered in vivo. One of the major causes of this unfavorable outcome is that proteins and other biomolecules adsorb onto the particles upon NPs' injection into the blood stream, and form a biological coating named "protein corona." Protein corona formation could remarkably affect NPs' blood circulation, their cellular uptake, and targeting efficiency. Because current methods, such as PEGylation, could not fully resolve this issue, we aimed to address this challenge by exploiting the protein corona itself instead for targeted NP delivery. Here, we used the well-established opsonin-mediated phagocytosis of NPs to investigate if it is feasible to form an opsonin-enriched corona that actively targets NPs to immune cells by pre-coating NPs with gamma-globulins to promote the adsorption of opsonins (i.e. immunoglobulins) onto the NPs. Our results showed that while the corona of the gamma-globulin pre-coated NPs became enriched with opsonins upon incubation with human plasma, this enrichment did not enhance NP uptake by the target immune cells. Evaluation of the accessibility of immunoglobulins in the opsonin-enriched protein corona indicated that these proteins were not able to interact with their target biomolecules due to the screening effect of the other plasma proteins in the corona. Therefore, it is essential to control the spatial location of targeting proteins in the corona in order to form a functional corona for targeted NP delivery. In this work to exploit the protein corona for targeted NP delivery, the NPs were incubated with human plasma in vitro to mimic protein corona formation in the blood stream. However, other biological mediums, such as human serum, could be used in vitro for protein corona formation. The effect of these solutions, human serum or human plasma, on the corona's composition and NP's interactions with biological systems had not been thoroughly investigated. To address this issue, we exposed NPs to human serum and human plasma solutions and assessed the differences in these two protein coronas, and whether they affected NP uptake by cells. Our study demonstrates that NPs exposed to human plasma have larger diameters, more bound proteins, and more opsonins (e.g. fibrinogen) in their coronas than serum-exposed NPs. The presence of more opsonins in the coronas of the plasma-exposed NPs resulted in higher macrophage uptake of these particles than NPs exposed to human serum. Because, these two biological solutions yield protein coronas with different compositions, and human plasma better mimics the protein composition in the blood stream, human plasma should be utilized for in vitro protein corona studies. A challenge in the area of regenerative medicine was also addressed. Artificial cell cultures have been developed to identify the factors that direct hematopoietic stem cells (HSCs) to differentiate into specific lineages. Due to the rarity of stem cells, the number of HSCs utilized in these cultures must be minimized. However, HSC populations exhibit high cell-to-cell heterogeneity, so the culture must contain enough cells to elicit the full range of fate decisions found in the body. This creates a need for new tools for characterizing the heterogeneity of HSC populations. Here, we show the heterogeneity between and within hematopoietic cell populations can be visualized by developing self organizing map (SOM) models of time-of-flight secondary ion mass spectrometry data that contains information about biomolecules on the surfaces of these cells. The SOM models developed for B cells, common lymphoid progenitors (CLPs), and hematopoietic stem and progenitor cells (HSPCs) suggested that B cells are the least heterogeneous and the CLPs are the most heterogeneous of these three hematopoietic cell populations.
Issue Date:2016-06-03
Rights Information:Copyright 2016 Vahid Mirshafiee
Date Available in IDEALS:2016-11-10
Date Deposited:2016-08

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