A Nanomedicine Transports a Peptide Caspase-3 Inhibitor across the Blood–Brain Barrier and Provides Neuroprotection

Abstract

Caspases play an important role as mediators of cell death in acute and chronic neurological disorders. Although peptide inhibitors of caspases provide neuroprotection, they have to be administered intracerebroventricularly because they cannot cross the blood-brain barrier (BBB). Herein, we present a nanocarrier system that can transfer chitosan nanospheres loaded with N-benzyloxycarbonylAsp(OMe)-Glu(OMe)-Val-Asp(OMe)-fluoromethyl ketone (Z-DEVD-FMK), a relatively specific caspase-3 inhibitor, across BBB. Caspase-3 was chosen as a pharmacological target because of its central role in cell death. Polyethylene glycol-coated nanospheres were conjugated to an anti-mouse transferrin receptor monoclonal antibody (TfRMAb) that selectively recognizes the TfR type 1 on the cerebral vasculature. We demonstrate with intravital microscopy that this nanomedicine is rapidly transported across the BBB without being measurably taken up by liver and spleen. Pre-or post-treatment (2 h) with intravenously injected Z-DEVD-FMK-loaded nanospheres dose dependently decreased the infarct volume, neurological deficit, and ischemia-induced caspase-3 activity in mice subjected to 2 h of MCA occlusion and 24 h of reperfusion, suggesting that they released an amount of peptide sufficient to inhibit caspase activity. Similarly, nanospheres inhibited physiological caspase-3 activity during development in the neonatal mouse cerebellum on postnatal day 17 after closure of the BBB. Neither nanospheres functionalized with TfRMAb but not loaded with Z-DEVD-FMK nor nanospheres lacking TfRMAb but loaded with Z-DEVD-FMK had any effect on either paradigm, suggesting that inhibition of caspase activity and subsequent neuroprotection were due to efficient penetration of the peptide into brain. Thus, chitosan nanospheres open new and exciting opportunities for brain delivery of biologically active peptides that are useful for the treatment of CNS disorders.

Functional motor recovery from brain ischemic insult by carbon nanotube-mediated siRNA silencing

“…Moreover, functional recovery and rehabilitation was not studied in order to assess the efficacy of either treatment strategies. In agreement with the results obtained in the present study, Karatas et al (6) showed that treatment before the onset of ischemia was more effective in reducing the infarct volume than treatment after the ischemic insult. Intriguingly, a very recent study showed that preinfarct intracerebroventricular treatment with amine-functionalized singlewalled carbon nanotubes could improve tolerance of neurons to ischemic injury in the middle cerebral artery occlusion stroke model (39).…”

“…5), however this trend was not statistically significant as seen in the case of the treatment protocol before ischemic damage was induced. Similar observations of moderate therapeutic effects obtained postischemic damage induction (compared to pretreatment) have previously been reported for other therapeutic modalities (6). We therefore concluded that a neuroprotective effect could be reproducibly obtained from a single f -CNT:siCas 3 stereotactic administration before and after ET-1 induced ischemic damage, however more significant effects were obtained when the treatment was carried out prior to the ischemic insult.…”

“…Indeed, Caspase-3 activation contributes to brain tissue loss and downstream biochemical events leading to programmed cell death after traumatic brain injury (3,4). Both genetic disruption and pharmacological inhibition of caspases after stroke can reduce ischemic neuronal injury inducing a neuroprotective effect (5)(6)(7)(8). It has been suggested that silencing of apoptotic genes using in vivo RNA interference (RNAi) could be potentially an effective treatment for stroke (5,9) .…”

Identification of Novel Specific Allosteric Modulators of the Glycine Receptor Using Phage Display

“…Cell-penetrating peptides have long been used to deliver drugs into cellular cytoplasm, but recently, this technology has also been used to target bioactive peptides to brain tissue (32). Nanoparticles, a more recently developed technology, have also been highly successful in delivering systemically administered peptides into brain tissue at pharmacologically relevant concentrations (33). Efforts are also being made to improve the oral delivery of peptides to increase their marketability as therapeutic agents (34).…”

The executioners sing a new song: killer caspases activate microglia

“…Different strategies might be useful for this purpose: (i) A first approach may be suppression of caspase by targeted delivery of small interfering RNA specifically to macrophage/ microglial cells; 101 and (ii) the development of specific nontoxic nanocarriers able to cross the blood-brain barrier and to safety release caspase inhibitors in those areas showing high microgliosis. 102 These are great technical challenges, but the new insights into the non-lethal roles of caspases in microglia certainly support that it could be worthwhile and indicate that the idea of inhibiting caspases as a therapy for neurodegenerative diseases is anything but dead.…”