Peptides and the Blood–Brain Barrier: Research Challenges

The blood–brain barrier helps regulate which substances enter the central nervous system. Many peptides cross it poorly because of their size, polarity and susceptibility to degradation. Scientists study transport pathways and delivery strategies, but findings in cell models or animals do not guarantee human brain exposure. Even evidence that a molecule reaches the brain does not establish a therapeutic benefit. Responsible reporting separates transport measurements, biological effects and clinical outcomes, while acknowledging possible safety concerns associated with altering delivery.