Affiliations: Department of Neuropathology,
Ruprecht-Karls-University, Heidelberg, Germany
Note: [] Present address: Department of Neurosurgery,
Heinrich-Heine-Univer-sity, Düsseldorf, Germany
Note: [] Corresponding author: Clemens Sommer, MD, Department of
Neuro-pathology, Ruprecht-Karls-University of Heidelberg, Im Neuenheimer Feld
220, D-69120 Heidelberg, Germany. Tel.: +49 6221 562681; Fax: +49 6221 564566;
E-mail: Clemens_Sommer@med.uni-heidelberg.de
Abstract: Purpose: Transforming growth factor beta 2 (TGFâ2) is a
multifunctional cytokine thought to play a crucial role in neuronal growth,
differ-entiation and survival. In the cortex of adult rats, TGFâ2 is
constitutively expressed in a subset of neurons and astrocytes. In the present
study we analyzed whether TGFâ2 is also present in intrastriatal
transplants of cortical anlage. In addition we investigated the temporo-spatial
expression pattern of TGF2 in âthe surrounding host striatum. Methods:
Cortical primordia of rat fetuses (E14) were stereotactically grafted into the
rostral striatum of adult recipient rats. Grafts were allowed to differentiate
for 1, 2, 3, 4, 8 weeks or one year, respectively, followed by morphological
and immunohistochemical analysis. Results: From week 2 on, TGFâ
2-immunoreactivity (IR) was detectable in transplanted neurons. Within the
graft, GFAP-IR was already present one week after transplantation, whereas
TGFâ2-immunostained astrocytes were first seen after 2 weeks. One year
after transplanta-tion, TGFâ2 positive neurons and astrocytes were still
present. In the host striatum and at the graft-host interface an increase of
TGFâ2-immu-noreactive astrocytes first occured after one week both in
grafted animals and in sham-operated (lesioning without grafting) rats.
Conclusions: Our data suggest that at least a subpopulation of transplanted
neurons develops a phenotype as cortical neurons in situ with respect to
TGFâ2 expression. Upregulation of astrocytic TGFâ2 expression within
the graft, however, is due to the trauma imposed by the transplantation
procedure rather than an intrinsic differentiation program of co-grafted
astrocytes.
