Gene therapy of Hunter syndrome: Evaluation of the efficiency of muscle electro gene transfer for the production and release of recombinant iduronate-2-sulfatase (IDS)

Abstract

Mucopolysaccharidosis type II (MPSII) is an inherited disorder due to a deficiency of the lysosomal enzyme iduronate-2-sulfatase (IDS). The disease is characterized by a considerable deposition of heparan- and dermatan-sulfate, causing a general impairment of physiological functions. Most of the therapeutic protocols proposed so far are mainly based upon enzyme replacement therapy which is very expensive. There is a requirement for an alternative approach, and to this aim, we evaluated the feasibility of muscle electro gene transfer (EGT) performed in the IDS-knockout (IDS-ko) mouse model. EGT is a highly efficient method of delivering exogenous molecules into different tissues. More recently, pre-treatment with bovine hyaluronidase has shown to further improve transfection efficiency of muscle EGT. We here show that, by applying such procedure, IDS was very efficiently produced inside the muscle. However, no induced IDS activity was measured in the IDS-ko mice plasma, in contrast to matched healthy controls. In the same samples, an anticipated and rapidly increasing immune response against the recombinant protein was observed in the IDS-ko vs control mice, although reaching the same levels at 5 weeks post-injection. Additional experiments performed on healthy mice showed a significant contribution of hyaluronidase pre-treatment in increasing the immune response.

Genistein reduces glycosaminoglycan levels in a mouse model of mucopolysaccharidosis type II

“…Tissue GAG content was measured by using Bjornsson's protocol (Bjornsson, 1993), with modifications previously described (Friso et al, 2008). Briefly, tissues were lyophilized and then homogenized in 0.9% NaCl + 0.2% Triton X-100.…”

Gene therapy approaches for lysosomal storage disorders, a good model for the treatment of mendelian diseases

“…Electro gene transfer (EGT) has been used to introduce DNA into various mouse and rat tissues and successfully proposed to improve transfection of skeletal muscle with plasmid DNA (29). Our group evaluated the feasibility of muscle EGT performed in the MPS II mouse model to deliver a plasmid carrying the IDS gene (30). Despite the elevated production of the protein inside the muscle, a limited release into the bloodstream along with a strong anti-IDS immune response were detected, and no therapeutic effect was observed.…”

Skeletal Muscle Metabolism in the Pathology and Treatment of Type 1 Diabetes

“…Hyaluronidase pretreatment of the muscle before plasmid injection was early on established as a way to significantly enhance the gene transfer efficiency of EGT while simultaneously reducing muscle damage [191]. However, the contribution of hyaluronidase pre-treatment in increasing the immune response to the transgene has been suggested [192]. Protocols that avoid the use of hyaluronidase while retaining optimal gene transfer efficiency have also been developed [190].…”