D description in the CPP internalization mechanisms, and also other properties which include stability, toxicity and immunogenicity were reviewed elsewhere [199]. Here we concentrate on use of CPPs for delivery of proteins to CNS. Schwarze and colleagues published a seminal work demonstrating capacity of CPP to provide proteins across BBB [200]. In their study the NH2-terminal TAT (477)-galactosidase fusion protein (120 kDa) CD147 Proteins Recombinant Proteins 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 had been performed. Nevertheless galactosidase activity was visualized in sagittal and coronal brain sections too as in liver, kidney, lung and heart (myocardium) and spleen. TAT didn’t appear to disrupt BBB because 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. in 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 therapy did not stop the loss of dopaminergic neurons in PD mice, possibly because the quantity of the fusion protein delivered towards the target web page was not sufficient [201]. A TAT-based method was also employed to provide Bcl-xL protein, a well-characterized death-suppression molecule, to the CNS for remedy of stroke. Intraperitoneal injection of TAT and Bcl-xL fusion protein resulted inside a robust protein transduction in neurons, plus a dose-dependent decrease of cerebral infarction in a mouse middle cerebral artery occlusion (MCAO) model of ischemic stroke [202]. Similarly, a decreased infarct volume and neurological deficits have been observed soon after i.v. injection of TAT-Bcl-xL fusion protein 1 hr. before or immediately after the ischemia induced in a rat MCAO model [203]. A CD1d Proteins Species recent study reported that TAT-leptin fusion protein was i.v. injected to mice fed with high-fat eating plan. Immunohistochemical stainingNIH-PA Author Manuscript NIH-PA Author Manuscript NIH-PA Author ManuscriptJ Control Release. Author manuscript; available in PMC 2015 September 28.Yi et al.Pagesuggested boost in leptin accumulation in hypothalamus inside the TAT-leptin treated mice, when compared with the unmodified leptin or saline-treated animals. Importantly, TAT-leptin also prevented body-weight acquire more efficiently when compared with leptin [204]. Cai et al. lately described positive effects of TAT-mediated delivery of neuroglobin (Ngb) on focal cerebral ischemia outcome in mice [205]. Soon 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 improved neurologic outcomes compared to the control groups. Furthermore, the group treated with TAT-Ngb right after MCAO and reperfusion showed significantly increased neuronal survival inside the striatum, when compared with the controls [205]. In addition to TAT some other CPPs, for example Syn-B vectors and Rabies virus glycoproteinderived peptide (RDP), have been also shown to deliver smaller molecules and proteins across BBB [206, 207]. For instance, Xiang et al reported effective hippocampus targeting by a galactosidase-RDP fusion protein [206]. Interestingly, a easy mixing of a protein with CPP also improved delivery of numerous proteins such as -galactosidase, human IgG and IgM to mouse brain [208]. However, CPP have displayed different toxicities includin.