Using Cell-Penetrating Peptides to Deliver Drugs Inside Cells for Inflammation and Oxidative Stress Diseases

This is a narrative review article that surveyed the published scientific literature on cell-penetrating peptide-mediated delivery of therapeutic peptides and proteins. The authors examined studies covering in vitro (cell culture) and in vivo (animal) applications, focusing specifically on diseases involving oxidative stress, inflammatory pathways, and apoptosis.

A huge number of therapeutic peptides and proteins have been identified that could treat conditions from neurodegenerative diseases to chronic inflammation — but many of them can't get inside cells where they need to work. Cell-penetrating peptides offer a potential universal delivery solution. If the challenges of specificity and safety can be solved, CPP technology could unlock an entire class of intracellular peptide therapies that are currently stuck in the lab.

This review sits at the intersection of peptide therapeutics and drug delivery — two of the fastest-growing areas in pharmaceutical research. As more peptide drugs are discovered, the delivery problem becomes the bottleneck. CPPs represent one of several competing approaches (alongside nanoparticles, liposomes, and conjugation strategies) to solving intracellular delivery. Progress in making CPPs more specific and stable could transform how peptide medicines are administered.

As a narrative review, this paper synthesizes existing literature but does not generate new data or perform systematic quality assessment of the studies it covers. The conclusions are only as strong as the individual studies reviewed. Publication bias may favor positive CPP results. The review does not quantify efficacy across studies or provide meta-analytic evidence.