D description from the CPP internalization TLR1 site mechanisms, along with other properties such as stability, toxicity and immunogenicity were reviewed elsewhere [199]. Here we focus on use of CPPs for delivery of proteins to CNS. Schwarze and colleagues published a seminal function demonstrating potential of CPP to deliver proteins across BBB [200]. In their study the NH2-terminal TAT (477)-galactosidase fusion protein (120 kDa) injected i.p. in mice was detected by immunochemical staining initially at 2 hr in brain microvessels and after that at four hr in brain parenchyma. No PK studies were performed. Nevertheless galactosidase activity was visualized in sagittal and coronal brain αvβ6 drug sections too as in liver, kidney, lung and heart (myocardium) and spleen. TAT did not appear to disrupt BBB as the Evan’s blue albumin complexes co-injected with TAT were excluded in the brain tissues. Subsequently, TAT peptide was fused with GDNF and injected i.p. within a mouse model of PD. The fusion protein crossed the BBB and reached substantia nigra as was shown by immunohistochemical staining. Having said that, the remedy did not avert the loss of dopaminergic neurons in PD mice, possibly since the level of the fusion protein delivered to the target internet site was not adequate [201]. A TAT-based technique was also made use of to provide Bcl-xL protein, a well-characterized death-suppression molecule, for the CNS for treatment of stroke. Intraperitoneal injection of TAT and Bcl-xL fusion protein resulted inside a robust protein transduction in neurons, as well as a dose-dependent decrease of cerebral infarction within a mouse middle cerebral artery occlusion (MCAO) model of ischemic stroke [202]. Similarly, a lowered infarct volume and neurological deficits were observed immediately after i.v. injection of TAT-Bcl-xL fusion protein 1 hr. ahead of or immediately right after the ischemia induced within a rat MCAO model [203]. A recent study reported that TAT-leptin fusion protein was i.v. injected to mice fed with high-fat diet regime. Immunohistochemical stainingNIH-PA Author Manuscript NIH-PA Author Manuscript NIH-PA Author ManuscriptJ Manage Release. Author manuscript; available in PMC 2015 September 28.Yi et al.Pagesuggested boost in leptin accumulation in hypothalamus within the TAT-leptin treated mice, when compared with the unmodified leptin or saline-treated animals. Importantly, TAT-leptin also prevented body-weight achieve extra effectively when compared with leptin [204]. Cai et al. recently described constructive effects of TAT-mediated delivery of neuroglobin (Ngb) on focal cerebral ischemia outcome in mice [205]. Just after i.v. injection the TAT-Ngb fusion protein was detected in mice brain tissues by immunohistochemistry and western blotting. The group treated with TAT-Ngb two hr. before MCAO showed smaller brain infarct volume and enhanced neurologic outcomes compared to the manage groups. Furthermore, the group treated with TAT-Ngb following MCAO and reperfusion showed considerably enhanced neuronal survival in the striatum, in comparison with the controls [205]. Besides TAT some other CPPs, including Syn-B vectors and Rabies virus glycoproteinderived peptide (RDP), have been also shown to provide tiny molecules and proteins across BBB [206, 207]. As an example, Xiang et al reported efficient hippocampus targeting by a galactosidase-RDP fusion protein [206]. Interestingly, a straightforward mixing of a protein with CPP also enhanced delivery of many proteins including -galactosidase, human IgG and IgM to mouse brain [208]. However, CPP have displayed numerous toxicities includin.
