|Endogenous polysialylated neural cell adhesion molecule enhances the survival of retinal ganglion cells. |
Murphy, JA; Hartwick, AT; Rutishauser, U; Clarke, DB
Investigative ophthalmology & visual science
During development, all retinal cells express polysialylated neural cell adhesion molecule (PSA-NCAM). PSA is localized only on glia in the adult retina, but as Müller glial processes ensheathe most retinal neurons, PSA remains in the extracellular environment of adult neurons. The authors sought to investigate the influence of endogenous PSA on the survival of neonatal as well as adult normal and injured retinal ganglion cells (RGCs).Endogenous retinal PSA was selectively degraded by application of endoneuraminidase. PSA presence and removal were confirmed by immunohistochemistry and levels were assessed by Western Blot analysis. Neonatal RGC survival after PSA removal was assessed in vitro in RGCs immunopanned from rat pups. Adult RGC survival was assessed in vivo in mice by investigating RGC densities after removal of PSA in normal retinas and after optic nerve transection.Virtually all neonatal RGCs express PSA-NCAM and survive well in vitro; however, removal of PSA resulted in a 42% loss of these cells 3 days after the treatment. Similarly, removal of PSA in the adult retina in vivo induced a loss of 25% of RGCs at 14 days, and significantly reduced RGC densities after optic nerve transection by an additional 27% (relative to injured retinas with a vehicle injection) at 7 days.Together, these findings demonstrate that endogenous PSA supports the survival of neonatal as well as injured and normal adult RGCs and provide the first functional evidence of a role for PSA in the adult retina.
|Progenitor cell therapy in a porcine acute myocardial infarction model induces cardiac hypertrophy, mediated by paracrine secretion of cardiotrophic factors including TGFbeta1. |
Doyle, B; Sorajja, P; Hynes, B; Kumar, AH; Araoz, PA; Stalboerger, PG; Miller, D; Reed, C; Schmeckpeper, J; Wang, S; Liu, C; Terzic, A; Kruger, D; Riederer, S; Caplice, NM
Stem cells and development
Administration of endothelial progenitor cells (EPC) is a promising therapy for post-infarction cardiac repair. However, the mechanisms that underlie apparent beneficial effects on myocardial remodeling are unclear. In a porcine model of acute myocardial infarction, we investigated the therapeutic effects of a mixed population of culture modified peripheral blood mononuclear cells (termed hereafter porcine EPC). Porcine EPC were isolated using methods identical to those previously adopted for harvest of EPC in human cell therapy studies. In addition the therapeutic effects of paracrine factors secreted by these cells was evaluated in vitro and in vivo. Intracoronary injection of autologous porcine EPC was associated with increased infarct territory mass and improved regional ventricular systolic function at 2 months compared to control. Treatment with conditioned media derived from autologous EPC was associated with similar improved effects on infarct territory mass and function. Histologic analysis of the infarct territory revealed significantly increased cardiomyocyte size in EPC and conditioned media treated groups, when compared to controls. A paracrine EPC effect was also verified in a pure myocardial preparation in which cardiomyocytes devoid of fibroblast, neuronal and vascular elements directly responded by increasing cell mass when exposed to the same conditioned media. Analysis of conditioned media revealed elevated levels of TGFbeta1 (human 267.3+/-11.8 pg/ml, porcine 57.1+/-6.1 pg/ml), a recognized mediator of hypertrophic signaling in the heart. Neutralizing antibodies to TGFbeta1 attenuated the pro-hypertrophic effect of conditioned media, and use of recombinant TGFbeta1 added to fresh media replicated the pro-hypertrophic effects of conditioned media in vitro. These data demonstrate the potential of paracrine factors secreted from endothelial progenitor cells to induce cardiomyocyte hypertrophy contributing to increased infarct territory LV mass, with favorable medium term effects on regional function following myocardial infarction.