We investigated the phenotypic and molecular characteristics of a rare human adult bone marrow (ABM) CD34+CD38-/loCD7+CD10- population that comprise 0.04% of the total bone marrow mononuclear cells in search of a human committed T cell progenitor (hCTP). Using multi-color flow cytometry, we investigated our putative hCTP for its cell surface phenotype and sorted cells for molecular analysis. We observed that our putative hCTP population expresses low levels of T cell lineage associated surface markers CD1a and CD5; the chemokine receptors implicated with progenitor migration to the thymus CCR7, CCR9, CXCR6; and lymphoid associated surface markers CD127, CD45RA, and CD24. Using the comparative CT quantitative PCR method, we established a gene expression profile of our putative hCTP. Molecular analysis reveals that the putative hCTP population lacks expression of T cell lineage genes (Gata-3, CD7, CD3) and the lymphoid lineage associated gene Rag-1. However, expression of PU.1 and Id2 is present in this population, similar to early thymocytes. Based on our results, we conclude that this population resembles the human early thymic progenitor, and is capable of seeding the thymus.

Tissue engineering (TE) is an emergent interdisciplinary field that promises to increase our understanding of challenging issues in biomedical research that may facilitate tissue regeneration, or the replacement of dysfunctional organs and tissues. An approach of TE integrates cell sources, and materials into in vitro engineered substrates that may facilitate generation of tissue- like constructs, which may be used to understand pathological conditions, test pharmacological agents or elucidate pharmacokinetics, or as cell constructs for tissue replacement. Cardiac tissue, with its native in vivo complexity, represents a major challenge when trying to explain its physio- anatomical characteristics in vitro. Advances in cardiovascular tissue engineering may be improved by incorporation of materials that mimic the complex heart tissue environment, preferably those derived from primary cell sources. My findings indicate that integrating a multi- scale surface topography. along with extracellular matrix elements (ECM). facilitates the generation of confluent anisotropic cell mono-layers of fetal cardiomyocytes (FCM), neonatal cardiomyocytes NNCM, or derived from murine and human embryonic stem cells (CMdESC). In the case of primary cardiac cells, cardiac fibroblasts CF promote cell survival and phenotype. Also, my findings provide insight into the Cardiac fibroblast subpopulation including the importance of signaling derived elements to promote generation of in vitro cardiac micro environments. Importantly I developed a novel simplistic, cost-efficient, tunable, multi- scale fabrication approach to produce cell culture substrates with multi-scale feature topography for the alignment of cells that improve cell connectivity while enhancing and maintaining phenotypic characteristics.

This study suggests that for promoting and enhancing functionality and phenotypic characteristics of CM cultured in in vitro conditions, it is favorable to integrate multiple biomimetic cardiac microenvironmental factors into tissue culture systems.

The contribution of CD8 T cells to autoimmune disease remains in debate. We show autoimmune CD8 T cells which induce antibody class switching and plasma cell differentiation act synergistically with CD4 T cells in promoting germinal center reactions. We have identified CXCR5+PD-1+ CD8 effector T (CD8 T follicular; Tfc) cells, within the germinal center, that expand during late autoimmune disease progression. We show that CD8 Tfc cells transcriptionally and phenotypically resemble CD4 T follicular helper (Tfh) cells in multiple models of spontaneous autoantibody-mediated disease including IL-2 deficient (IL-2-KO), scurfy and MRL/MpJ-FASlpr mice. CD8 Tfc cells maintain the capacity to produce significant amounts of cytotoxic proteins granzyme B, CD107a and TNFα, and helper-associated cytokines IL-21, IFNγ and IL-4. Functionally, CD8 Tfc cells promote cytokine-mediated antibody class switch using mechanisms largely independent of IFNγ or IL-21. When adoptively transferred CD8 Tfc cells in combination with CD4 Tfh cell promote autoantibody production. Our results indicate that CD8 Tfc cells contribute to autoimmune disease synergistically with CD4 Tfh cells to induce B cell class switching and autoantibodies during disease progression. Autoimmune disease is a novel immune setting during which CXCR5+ CD8 T cells develop beyond situations of chronic viral infection and cancer. Thus, pathogenic CD8 T cells influence germinal center reactions and promote autoimmune responses.