A therapeutic compound consisting of human telomerase, its catalytic subunit hTert, or a known variant of either, and a biodegradable nanoparticle carrier, which can be administered to cells in a cell culture or in a living animal, is provided herein. The therapeutic compound is envisioned as a method for treating a wide variety of age-related diseases such as idiopathic pulmonary fibrosis, aplastic anemia, dyskeratosis congenita, arteriosclerosis, macular degeneration, osteoporosis, Alzheimer's, diabetes type 2, and any disease that correlates with telomere shortening and may be corrected or ameliorated by lengthening telomeres. The therapeutic compound is also envisioned as method for potentially treating more generic problems of human aging. The nanoparticle carrier is comprised of certain biodegradable biocompatible polymers such as poly(lactide-co-glycolide), poly(lactic acid), poly(alkylene glycol), polybutylcyanoacrylate, poly(methylmethacrylate-co-methacrylic acid), poly-allylamine, polyanhydride, polyhydroxybutyric acid, polycaprolactone, lactide-caprolactone copolymers, polyhydroxybutyrate, polyalkylcyanoacrylates, polyanhydrides, polyorthoester or a combination thereof. The nanoparticle may incorporate a targeting moiety to direct the nanoparticle to a particular tissue type or a location within a cell. The nanoparticle may incorporate a plasticizer to facilitate sustained release of telomerase such as L-tartaric acid dimethyl ester, triethyl citrate, or glyceryl triacetate. A nanoparticle of the present invention can further contain a polymer that affects the charge or lipophilicity or hydrophilicity of the particle. Any biocompatible hydrophilic polymer can be used for this purpose, including but not limited to, poly(vinyl alcohol).