Cell-Penetrating Peptides Selectively Cross the Blood-Brain Barrier In Vivo.

Sofie Stalmans,Ingeborgh Polis,Nathalie Bracke,Kathelijne Peremans,Christian Burvenich,Bert Gevaert,Evelien Wynendaele,Bart De Spiegeleer,Je-Min Choi

doi:10.1371/journal.pone.0139652

Abstract

Cell-penetrating peptides (CPPs) are a group of peptides, which have the ability to cross cell membrane bilayers. CPPs themselves can exert biological activity and can be formed endogenously. Fragmentary studies demonstrate their ability to enhance transport of different cargoes across the blood-brain barrier (BBB). However, comparative, quantitative data on the BBB permeability of different CPPs are currently lacking. Therefore, the in vivo BBB transport characteristics of five chemically diverse CPPs, i.e. pVEC, SynB3, Tat 47–57, transportan 10 (TP10) and TP10-2, were determined. The results of the multiple time regression (MTR) analysis revealed that CPPs show divergent BBB influx properties: Tat 47–57, SynB3, and especially pVEC showed very high unidirectional influx rates of 4.73 μl/(g × min), 5.63 μl/(g × min) and 6.02 μl/(g × min), respectively, while the transportan analogs showed a negligible to low brain influx. Using capillary depletion, it was found that 80% of the influxed peptides effectively reached the brain parenchyma. Except for pVEC, all peptides showed a significant efflux out of the brain. Co-injection of pVEC with radioiodinated bovine serum albumin (BSA) did not enhance the brain influx of radiodionated BSA, indicating that pVEC does not itself significantly alter the BBB properties. A saturable mechanism could not be demonstrated by co-injecting an excess dose of non-radiolabeled CPP. No significant regional differences in brain influx were observed, with the exception for pVEC, for which the regional variations were only marginal. The observed BBB influx transport properties cannot be correlated with their cell-penetrating ability, and therefore, good CPP properties do not imply efficient brain influx.

Highlights

Cell-penetrating peptides are a particular group of peptides that have the ability to cross cell membranes without causing a significant lethal membrane damage [1,2]
To evaluate whether different Cell-penetrating peptides (CPPs) cross the blood-brain barrier (BBB) to the same extent, we quantitatively investigated the BBB transport of five chemically diverse CPPs with different cell-penetrating ability (Table 1): pVEC, SynB3, Tat 47–57, transportan 10 (TP10) and TP10-2
The results of the multiple time regression (MTR) analysis indicated that the five investigated CPPs crossed the BBB to a different extent

Summary

Methods

Peptide qualityTP10 and TP10-2 were purchased at Caslo ApS (Lyngby, Danmark); pVEC, SynB3 and Tat 47–57 at LifeTein LLC (Somerset, USA) and the positive control dermorphin at Bachem (Bubendorf, Switzerland) and Hanhong group (Shanghai, China). SynB3, Tat 47–57, dermorphin and albumin (BSA) (Merck KGaA, Darmstadt, Germany) were radiolabeled using the Iodo-Gen method. A previously established procedure was used [45], but in case of Tat 47–57 and dermorphin, a 1 μmol/ml sodium iodide carrier solution was used. A volume containing 1 mCi of Na125I (Perkin Elmer, Zaventem, Belgium) was transferred to this solution, followed by 30 μl of a 0.5 mg/ml chloramine-T solution in 25 mM phosphate buffer (pH 7.4 (TP10 and TP10-2) or pH 8.5 (pVEC)). For evaluation of the used influx mechanism, pVEC, SynB3 and TP10 were radiolabeled using a no-carrier added protocol, in which the sodium iodide solution was replaced by its solvent

Results

Discussion

Conclusion