Therapeutic potential of human mesenchymal stem cells and insulin-like growth factor-I gene therapy in animal models of neurodegeneration

ZAPPA VILLAR MF; MOREL GR; GARCÍA MG; PARDO J; LÓPEZ-LEÓN M; TRÍPODI LS; MAZZOLINI G; GOYA RG; REGGIANI PC.

CABA

Congreso; 2nd FALAN congress; 2016

IBRO-FALAN

Cognitive aging and its most devastating expression, Alzheimer's Disease (AD), represent a growing medical and socioeconomic challenge that calls for vigorous research efforts across the globe to design effective therapeutic interventions. AD is associated with a progressive decline in cognitive function, as well as by the degeneration of neurons and reduced brain glucose metabolism.The signalling pathways that become defective with age in AD, altering the normal protein homoeostasis of amyloid β-peptide (Aβ) and tau protein, and thus initiating a series of pathophysiological responses ultimately causing synaptic loss and cognitive decline, are unclear and much sought after. Interestingly, a critical pathway appears to be the IIS [insulin/insulin-like growth factor 1(IGF-1)-like signalling] pathway, which is considered a major regulator of longevity and protein homoeostasis.In line with this, IGF-1 has been consistently shown to be a potent neuroprotective factor (Piriz et al., 2011). Intracerebroventricular (ICV) infusion of IGF-I in the lateral ventricle improves reference and working memory in aging rats (Markowska et al.,1998). It has been also documented that IGF-I protects hippocampal neurons from the toxic effects of amyloid peptides (Doré et al.,1997). Furthermore, IGF-1 treatment markedly reduces the brain burden of Aβ amyloid in transgenic mice carrying a mutant Aβ amyloid peptide (Carro et al., 2006).We are interested in developing therapeutic strategies for neurodegenerative disorders and brain aging. In this context, new biotechnological strategies like gene therapy combined with the use potent neuroprotective molecules, like IGF-1, emerge as promising therapeutic tool for the treatment of age-related neurodegeneration.We constructed a recombinant adenoviral vector harboring the gene for rat IGF-1 (RAd-IGF1) and it was successfully employed to implement restorative gene therapy in the brain of aging female rats. Briefly, we implemented 18-day long intracerebroventricular (ICV) IGF-I gene therapy in 28 months old Sprague-Dawley (SD) female rats, and assessed spatial memory performance in the Barnes maze. We also studied hippocampal morphology using an unbiased stereological approach. After treatment, the IGF-1 group showed a significant improvement in spatial memory accuracy as compared with control counterparts. In the dentate gyrus of the hippocampus, the IGF-1 group showed a higher number of immature neurons than the control counterparts. The treatment increased hippocampal astrocyte branching and reduced their number in the hippocampal stratum radiatum.More recently we set up a rat model of sporadic AD (by ICV injection of streptozotocin (STZ-icv)) and plan to implement human mesenchymal stem cell (MSC) therapy in our AD-model as well as in aging rats.In a first study we explored the therapeutic effect of human adult bone marrow-derived MSC in our AD rat model. Young SD male rats were divided into three experimental groups (N=6/group): intact, STZ and STZ+MSC. STZ and STZ+MSC groups received 3 mg/kg STZ-icv and, 24 hours later, the STZ+MSC group received 2x105 MSC. We assessed hippocampus-dependent learning and spatial memory by the Barnes maze and recognition memory by Novel Object Recognition test (NOR). After 24 days we sacrificed the animals. Rats that received cell therapy showed an improvement in their spatial memory performance (P<0.01 vs. STZ) and recognition memory (P<0.05, new vs. familiar objects). In this study we found that cell therapy improves cognitive deficits in our AD rat model.Comparable results were observed when we used a similar experimental design in 27-month-old female rats. Animals were separated in three experimental groups (N=8/group): Young-intact, Senile-intact and Senile-MSC. After 24 days of 5x105 MSC ICV injection we euthanaized animals. The most remarkable effect of the MSC treatment was on hole exploration in the Barnes maze where the treatment markedly increased exploratory frequency at the escape hole as compared to Senile-intact group (P<0.01).Finally, we assessed the effect of intravenous administration of other mesenchymal cells, the Human umbilical cord perivascular cells (HUCPVC) on cognitive performance in the AD rat model. Three experimental groups (N=6/group) were used: intact, STZ and STZ+MSC. After 24 days of STZ injection, animals received four times (every 18 days) a suspension of HUCPVC (1x106 cells in 1 ml) in one of the tail veins. During the last two weeks until the end of the study we performed Open Field, NOR, Barnes maze, Forced swimming and marble burying tests to estimate memory, depression-like and anxiety-like behaviors. Our preliminarily results show cognitive improvement in the HUCPVC-treated rats.We conclude that our results are in line with the emerging evidence that supports the use of MSCs for regenerative applications in neurodegenerative disorders and brain aging.