Isolation and characterization of human anterior cruciate ligament-derived vascular stem cells

The anterior cruciate ligament (ACL) usually fails to heal after rupture mainly due to the inability of the cells within the ACL tissue to establish an adequate healing process, making graft reconstruction surgery a necessity. However, some reports have shown that there is a healing potential of ACL with primary suture repair. Although some reports showed the existence of mesenchymal stem cell-like cells in human ACL tissues, their origin still remains unclear. Recently, blood vessels have been reported to represent a rich supply of stem/progenitor cells with a characteristic expression of CD34 and CD146. In this study, we attempted to validate the hypothesis that CD34- and CD146-expressing vascular cells exist in hACL tissues, have a potential for multi-lineage differentiation, and are recruited to the rupture site to participate in the intrinsic healing of injured ACL. Immunohistochemistry and flow cytometry analysis of hACL tissues demonstrated that it contains significantly more CD34 and CD146-positive cells in the ACL ruptured site compared with the noninjured midsubstance. CD34+CD45- cells isolated from ACL ruptured site showed higher expansionary potentials than CD146+CD45- and CD34-CD146-CD45- cells, and displayed higher differentiation potentials into osteogenic, adipogenic, and angiogenic lineages than the other cell populations. Immunohistochemistry of fetal and adult hACL tissues demonstrated a higher number of CD34 and CD146-positive cells in the ACL septum region compared with the midsubstance. In conclusion, our findings suggest that the ACL septum region contains a population of vascular-derived stem cells that may contribute to ligament regeneration and repair at the site of rupture. © 2012 Mary Ann Liebert, Inc

Effects of TH17 cell transfer on the airways (99.1)

Abstract A distinct subset of CD4+ T helper cells characterized by the production of IL-17A, IL-17F, and IL-6 has recently been discovered. The differentiation of TH17 cells is dependent on transforming growth factor-β and IL-6 while IL-23 is involved in function of TH17 cells in host defense. TH17 cells have been shown to contribute to the pathogenesis of some autoimmune disorders and models of allergic asthma show TH17 cells are involved in the development of allergic responses. In order to investigate the function of TH17 cells we polarized naïve CD4+ T cells from DO11.10 TCR transgenic mice by culturing in conditioned media containing OVA peptide, TGF-β, IL-6, IL-23, anti-IFN-γ and anti-IL-4. For comparisons we also generated TH0 cells (grown in IL-2 only) and polarized TH1 and TH2 cells.TH17 cells secreted &amp;gt; 5 ng/ml IL-17 in an antigen-recall response when stimulated with OVA peptide. Only transfer of TH17 cells into mice challenged with OVA protein resulted in increased chemokine secretion in the BAL fluid, including substantial levels of the IL-8 homolog KC whereas only transfer of Th2 cells resulted in eosinophil emigration into the lung. Both TH17 and TH2 cells resulted in increased mucous secreting cells in the airway. These data demonstrate that the polarized antigen specific T-cells result in specific lung pathologies.</jats:p

Novel IL-17–producing memory cells are key to vaccine-based protective immunity against M.tuberculosis challenge (45.12)

Abstract Interferon-gamma (IFNγ) is essential for limiting Mycobacterium tuberculosis infection. Using the mouse model, we have recently shown that vaccination triggered accelerated Interleukin-17 (IL-17) and IFNγ responses by CD4+ T cells in the lung during M. tuberculosis aerosol challenge. We propose that vaccination induces IL-17- producing CD4+ T cells that populate the lung and, after challenge, trigger the production of chemokines. The induction of chemokines results in recruitment of IFNγ-producing CD4+ T cells from the lymphoid compartment and ultimately restricts bacterial growth. The differential ability of IL-17-producing memory cells to populate the lung compared to the IFN-γ-producing cells suggests that these two cell types differ in their ability to migrate in response to chemokines. In support of this, our data using adoptive transfer models and chemotaxis assays suggests that differential responsiveness to chemokines and retention in different organs may provide the basis for the differential tissue distribution of these two cell types. During progression from effector to memory T cells, we also show differential expression of activation markers on IL17-producing and IFNγ-producing T cells. This information will lead us to determine whether altering the nature of the lung-resident IL-17 producing population impacts protective efficacy of the recall response to M.tuberculosis challenge. This work was supported by AI075106-01 and Children's Hospital of Pittsburgh.</jats:p