Author ORCID Identifier

0000-0001-6912-1458

Date of Graduation

5-2020

Document Type

Thesis (MS)

Program Affiliation

Biomedical Sciences

Degree Name

Masters of Science (MS)

Advisor/Committee Chair

Dr. Sean I. Savitz

Committee Member

Dr. Jaroslaw Aronowski

Committee Member

Dr. Matthew T. Harting

Committee Member

Dr. Harry Karmouty-Quintana

Committee Member

Dr. David W. Marshak

Committee Member

Dr. Scott D. Olson

Abstract

Background: Ischemic stroke is a leading cause of death and long-term disability

around the world. Current treatment options are limited to the administration of

tissue plasminogen activator (tPA) and/or endovascular therapy, administered within

a limited time window. However, cell-based therapies such as mesenchymal stromal

cells (MSCs) have increasingly shown great promise for ischemic stroke recovery

with some therapies already in various stages of clinical trials. Intravenous (IV)

administration of the MSCs leads to the entrapment of these MSCs in the lungs.

These entrapped MSCs interact with the pulmonary endothelial cells (PECs) and

could modulate the immune response through the release of cytokines and

chemokines. Monocyte Chemoattractant Protein - 1 (MCP-1), is an important

chemokine involved in the recruitment of monocytes and macrophages. In our study,

we wanted to explore the interactions between MSCs with PECs and how this

interaction changes the expression levels of MCP-1 and other cytokines after an

inflammatory event such as stroke. We also wanted to see if MCP-1 released

through the interaction between MSCs and PECs under inflammatory conditions,

modulates the immune response through the modification of monocytes.

Methods: Cultured murine PECs were grown either alone or in a combination of

murine MSCs, and were exposed to 1) a combination of IFN-γ and TNF-α

inflammatory stimuli or 2) Anti MCP-1 antibody to neutralize any secreted MCP-1.

The secretome release of IL-1β, IL-1ra, IL-6, MCP-1, and VEGF were analyzed

using ELISA (BD Biosciences and R&D Systems). To further understand the

immunomodulatory response, the collected media from the previous step was added

to splenic immune cells (CD11b+) and splenic monocytes (CD115+). The secretome

release was analyzed from these cells using ELISA.

Results: MCP-1 secretion levels were increased from PECs as well as co-cultures

of PECs and MSCs when they were exposed to inflammatory stimuli. When

cocultures of PECs and MSCs were exposed to recombinant MCP-1 or MCP-1

neutralizing antibody, VEGF secretion levels decreased. In the presence of

inflammatory stimuli, co-cultures of PECs and MSCs secreted elevated levels of

VEGF. While under inflammation, we also observed that IL-6 levels were elevated

and they remain elevated even when MCP-1 was neutralized. We did not observe

any difference in secretome release from neither the splenic immune cells (CD11b+)

nor the splenic monocytes (CD115+).

Conclusion: Our data show that MCP-1 release under stroke-like conditions is

modulated through the interaction of PECs and MSCs. However, our study was

unable to elucidate MCP-1’s role in the modification of monocytes.

Keywords

Stroke, Cell Therapy, Mesenchymal Stromal Cells, Pulmonary Endothelial Cells, Immunomodulation, Monocytes, MCP-1, IL-6, VEGF

Available for download on Tuesday, April 27, 2021

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