In spite that the use of naturally occurring neurotrophic factors like NGF, BDNF, CNTF, GDNF and others for treatment of neurodegenerative disorders seems promising because of their pharmacological properties, until now no large scale clinical trials have been published. One of the reasons is that these molecules are unable to penetrate through the blood brain barrier, making invasive application strategies like intracerebroventricular infusion necessary. Another one is the fact that in first clinical studies, several undesirable side-effects like hyperalgesia or weight loss have been reported. Major efforts are now put into development of improved application procedures and in treatment protocols for avoiding the known side-effects. Already 7 years ago it has been demonstrated that Cerebrolysin®, a peptidergic drug, produced from purified brain proteins by standardized enzymatic breakdown, containing biologically active peptides, is exerting nerve growth factor like activity on neurons from dorsal root ganglia. Still ongoing investigations are showing growth promoting efficacy of this drug in different neuronal populations from peripheral and central nervous system. The current findings are in accordance with several older publications, enabling now a more clear interpretation of these findings. In addition to the direct neurotrophic effect, the drug also shows clear neuroprotective properties after different types of lesion in vitro and in vivo, resembling the pharmacological activities of naturally occurring nerve growth factors. Neurotrophic and neuroprotective efficacy has been shown with a broad variety of methods in different models and it is remarkable that all biochemical and morphological drug dependent alterations are resulting in improvements of learning and memory. Because of these experimental results, clinical trials using cerebrolysin in Alzheimer's patients have been performed, demonstrating a quick improvement in the overall state of the patients, particularly enhancing the cognitive performance. It is remarkable that these effects are long lasting after cessation of the active treatment procedure. Even 6 months after stop of drug application, improvements in AD-patients are detectable. Therefore it is concluded that cerebrolysin is able to induce repair phenomena, resulting in long term stabilization. In contrast to the naturally occurring growth factors, tolerability of this drug is extremely high, without any reports about serious side-effects in these clinical studies.
Windisch, M., Gschanes, A., & Hutter-Paier, B. (1998). Neurotrophic activities and therapeutic experience with a brain derived peptide preparation. Journal of Neural Transmission, Supplement, (53), 289–298. https://doi.org/10.1007/978-3-7091-6467-9_25