Synaptosomes: new vesicles for neuronal mitochondrial transplantation

Abstract

Background Mitochondrial dysfunction is a critical factor in the onset and progression of neurodegenerative diseases. Recently, mitochondrial transplantation has been advised as an innovative and attractive strategy to transfer and replace damaged mitochondria. Here we propose, for the first time, to use rat brain extracted synaptosomes, a subcellular fraction of isolated synaptic terminal that contains mitochondria, as mitochondrial delivery systems. Results Synaptosome preparation was validated by the presence of Synaptophysin and PSD95. Synaptosomes were characterized in terms of dimension, zeta potential, polydispersity index and number of particles/ml. Nile Red or CTX-FITCH labeled synaptosomes were internalized in LAN5 recipient cells by a mechanism involving specific protein–protein interaction, as demonstrated by loss of fusion ability after trypsin treatment and using different cell lines. The loading and release ability of the synaptosomes was proved by the presence of curcumin both into synaptosomes and LAN5 cells. The vitality of mitochondria transferred by Synaptosomes was demonstrated by the presence of Opa1, Fis1 and TOM40 mitochondrial proteins and JC-1 measurements. Further, synaptosomes deliver vital mitochondria into the cytoplasm of neuronal cells as demonstrated by microscopic images, increase of TOM 40, cytochrome c, Hexokinase II mitochondrial proteins, and presence of rat mitochondrial DNA. Finally, by using synaptosomes as a vehicle, healthy mitochondria restored mitochondrial function in cells containing rotenone or CCCp damaged mitochondria. Conclusions Taken together these results suggest that synaptosomes can be a natural vehicle for the delivery of molecules and organelles to neuronal cells. Further, the replacement of affected mitochondria with healthy ones could be a potential therapy for treating neuronal mitochondrial dysfunction-related diseases.

Nano-structured myelin: new nanovesicles for targeted delivery to white matter and microglia, from brain-to-brain

“…6 c). In order to determine if the localization of MyVes to myelin sheath is specific, we used a vesicle of different nature, obtained from the synaptic terminals, called synaptosomal vesicle [ 22 ]. Results indicated that these vesicles showed a different localization with respect to MyVes, demonstrating the specificity of MyVes for white matter ( Fig.…”

“…Synaptosomal vesicles were isolated using the method descripted in Picone et al. [ 22 ]. Briefly, the cortex (60 ​mg) was quickly removed and homogenized in 180 ​μl of 0.32 ​M sucrose with 10% protease (Amersham Biosciences) and phosphatase cocktail inhibitors (cocktail II and III; Sigma-Aldrich) with a Dounce on ice.…”

“…In addition, the cell plasma membrane can be engineered to improve the performance and efficacy of the carrier. Recently, synaptosomes have been used as vesicles for delivery of the mitochondria (mitochondrial transplantation) in neuronal cells, against neurodegenerative diseases [ 22 ].…”

Promising Treatment for Multiple Sclerosis: Mitochondrial Transplantation

“…In particular, the polysaccharide dextran has been proposed to enhance stabilization without affecting mitochondria activity [31]. In this context, recently, structures obtained from synaptic terminations by physical processes (synaptosomes) have been proposed as vesicles for mitochondrial transfer into neuronal cells [32]. Synaptosomes transport viable mitochondria mainly in the cytoplasm of neuronal cells and restore mitochondrial function in cells containing rotenone-damaged mitochondria [32].…”

Mitochondrial Transplantation as a Novel Therapeutic Strategy for Mitochondrial Diseases

“…Another group showed that synaptosomes can be a natural vehicle for the delivery of mitochondria into the cytoplasm of neuronal cells. The transferred healthy mitochondria by synaptosomes restored mitochondrial function in human neuroblastoma cells (LAN5 cells) containing rotenone or carbonyl cyanide m-chlorophenyl hydrazone (CCCP)-damaged mitochondria [ 58 ].…”