Nerve growth factor released from collagen scaffolds protects axotomized cholinergic neurons of the basal nucleus of Meynert in organotypic brain slices

Background Alzheimeŕs disease is accompanied by cell death of cholinergic neurons, resulting in cognitive impairment and memory loss. Nerve growth factor (NGF) is the most potent protein to support survival of cholinergic neurons. New Method Organotypic brain slices of the basal nucleus of Meynert (nBM) are a valuable tool to study cell death of axotomized cholinergic neurons, as well as protective effects of NGF added into the medium. The aim of the present study is to use collagen scaffolds crosslinked with polyethyleneglycole and load with NGF to target delivery of NGF to organotypic nBM brain slices. Results Collagen scaffolds (visualized by incorporating AlexaFluor 488 antibodies) slowly degraded when applied onto organotypic brain slices within 2 weeks in culture. GFAP reactive astrocytes and Iba1+ microglia became visible around the collagen scaffolds 7 days after incubation, showing reactive gliosis. Cholinergic neurons of the nBM survived (201 ± 21, n = 8) when incubated with 100 ng/ml NGF in the medium compared to NGF-free medium (69 ± 12, n = 7). Collagen scaffolds loaded with NGF (1 ng/2 μl scaffold) significantly rescued cholinergic cell death in the nBM brain slices (175 ± 12, n = 10), which was counteracted by an anti-NGF antibody (77 ± 5, n = 5). Comparison with existing Methods The combination of coronal brain slices with biomaterial is a novel and potent tool to selectively study neuroprotective effects. Conclusions Collagen scaffolds loaded with low amounts of a protein/drug of interest can be easily applied directly onto organotypic brain slices, allowing slow targeted release of a protective molecule. Such an approach is highly useful to optimize CollScaff for further in vivo applications.