Through the paracrine effects of stem cells, including the secretion of neurotrophic, immunomodulatory, and
anti-apoptotic factors, cell-based therapies offer a new all-encompassing approach to treatment of neurodegenerative diseases. In this study, we used physically separated co-cultures of porcine neuroretina (NR) and human mesenchymal stem cells (MSC) to evaluate the MSC paracrine neuroprotective effects on NR degen-
eration. NR explants were obtained from porcine eyes and cultured alone or co-cultured with commercially
available MSCs from Valladolid (MSCV; Citospin S.L.; Valladolid, Spain), currently used for several approved
treatments. Cultures were maintained for 72h. MSC surface markers were evaluated before and after co-culture
with NRs. Culture supernatants were collected and the concentration of brain-derived neurotrophic factor
(BDNF), ciliary neurotrophic factor (CNTF), and glial-derived neurotrophic factor (GDNF) were determined by
enzyme-linked immunosorbent assays. NR sections were stained by haematoxylin/eosin or immunostained for
terminal deoxynucleotidyl transferase dUTP nick end labelling (TUNEL), glial fibrillary acidic protein, β-tubulin
III, and neuronal nuclei marker. NR morphology, morphometry, nuclei count, apoptosis rate, retinal ganglion
cells, and glial cell activation were evaluated. Treatment effects were statistically analysed by parametric or non-
parametric tests. The MSCs retained stem cell surface markers after co-culture with NR. BDNF and CNTF con-
centrations in NR-MSCV co-cultures were higher than other experimental conditions at 72h (p< 0.05), but no
GDNF was detected. NR general morphology, total thickness, and cell counts were broadly preserved in co-
cultures, and the apoptosis rate determined by TUNEL assay was lower than for NR monocultures (all p< 0.05).
Co-cultures with MSCV also protected retinal ganglion cells from degenerative changes and reduced reactive
gliosis (both p< 0.05). In this invitromodel of spontaneous NR degeneration, the presence of co-cultured MSCs
retarded neuroglial degeneration. This effect was associated with elevated concentrations of the neurotrophic
factors BDNF and CNTF. Our data suggest that the paracrine secretion of these, and possibly other molecules, are
a potential resource for the treatment of several neuroretinal diseases.
