IIBBA   05544
INSTITUTO DE INVESTIGACIONES BIOQUIMICAS DE BUENOS AIRES
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Effect of the immunological niche on adult neural stem cell biology
Autor/es:
PATRICIA MATHIEU, ANA PAULA PIANTANIDA, DANIELA BATTISTA, MARIANA GRACIARENA, FERNANDO PITOSSI
Reunión:
Congreso; ISSCR 8th Annual Meeting; 2010
Resumen:
The neurogenic niche is composed by a variety of signals that include
molecules from the immune system. Immune cytokines are known to be involved in
the proliferation, differentiation and survival of endogenous and transplanted
adult neural stem cells (NSC).
The
general objective of our work was to assess the
effects of immune signals on the biology of endogenous NSC and after NSC
transplantation.
In a previous work, we studied NSC proliferation and differentiation in
an altered neurogenic niche by adrenal gland removal (ADX). ADX increased adult
neurogenesis and activated microglial cells till stage 3. In addition, transforming
growth factor beta (TGF-b) expression was increased 10-fold in ADX animals and co-localized with
activated microglia. Furthermore, blockade of TGF-b biological activity
diminished neurogenesis in vivo.
Moreover, TGF-b was able to increase neuronal differentiation (bIII
tubulin expression) in NSC primary hippocampal and
subventricular zone (SVZ) cultures. TGF-b effects were
mediated by Smad 2/3 activation. Surprisingly, in SVZ cultures, the percentage of bIII tubulin-positive cells increased from 31.55% to 70.38% after 2 and 6 weeks in the
untreated culture, respectively. In addition, 40.73% and 57.90% of cells were
Nestin-positive at 2 weeks and 6 weeks in culture, respectively. On the
contrary, the fraction of GFAP+ cells decreased over the 6 week-period,
suggesting that the GFAP+ progenitors are lost by time in culture. At 6 weeks
the majority of cells also expressed Olig2 and Sox2 stem cells markers. The
addition of TGF-b to the NSC
culture produced an additional increased in III-expression.
Finally,
undifferentiated NSC were transplanted into the rat striatum and survival,
differentiation and the host inflammatory response were determined 1, 3 and 6
weeks after grafting. 6 weeks after
transplantation of untreated NSC, 31% of the transplanted cells survived
and inflammation was only evident in the grafted area. The percentage of
GFAP-positive grafted cells increased at 6 weeks post-transplantation, while
Nestin-positive cells declined over time. Only 15.78% of transplanted cells
were NeuN-positive at 6 weeks post-grafting.
These data show that TGF-b, an anti-inflammatory cytokine, possess pro-neurogenic effects in vivo
and in vitro. In addition, bIII expression increases with time in cultured NSC from the SVZ. Our
results also indicate that without any further stimulus, grafted NSC in the
striatum diverted to glial differentiation.