Skeletal disease is a major problem for children with mucopolysaccharidoses (MPS). Patients suffer from early onset osteoporosis and osteoarthritis, severely affecting their quality of life. We will evaluate a lentiviral gene therapy vector developed in-house for its capacity to transduce bone, cartilage, synovial and ligament cells in a mouse model of MPS VI. Our goal is to generate high level, sustained expression of the deficient MPS enzyme and alter the course of skeletal disease in MPS.