We have earlier shown that antisense morpholino oligomers are able to restore dystrophin expression by systemic delivery in body-wide skeletal muscles of dystrophic mdx mice. However, the levels of dystrophin expression vary considerably and, more importantly, no dystrophin expression has been achieved in cardiac muscle. In this study, we investigate the efficiency of morpholino-induced exon skipping in cardiomyoblasts and myocytes in vitro, and in cardiac muscle in vivo by dose escalation. We showed that morpholino induces targeted exon skipping equally effectively in both skeletal muscle myoblasts and cardiomyoblasts. Effective exon skipping was achieved in cardiomyocytes in culture. In the mdx mice, morpholino rescues dystrophin expression dose dependently in both skeletal and cardiac muscles. Therapeutic levels of dystrophin were achieved in cardiac muscle albeit at higher doses than in skeletal muscles. Up to 50 and 30% normal levels of dystrophin were induced by single systemic delivery of 3 g kg -1 of morpholino in skeletal and cardiac muscles, respectively. High doses of morpholino treatment reduced the serum levels of creatine kinase without clear toxicity. These findings suggest that effective rescue of dystrophin in cardiac muscles can be achieved by morpholino for the treatment of Duchenne muscular dystrophy.

Exon skipping has demonstrated great potential for treating Duchenne muscular dystrophy (DMD) and other diseases. We have developed a drug-screening system using C2C12 myoblasts expressing a reporter green fluorescent phosphate (GFP), with its reading frame disrupted by the insertion of a targeted dystrophin exon. A library of 2,000 compounds (Spectrum collection; Microsource Discovery System) was screened to identify drugs capable of skipping targeted dystrophin exons or enhancing the exon-skipping effect by specific antisense oligomers. The 6-thioguanine (6TG) was effective for inducing skipping of both human dystrophin exon 50 (hDysE50) and mouse dystrophin exon 23 (mDysE23) in the cell culture systems and increased exon skipping efficiency (more than threefolds) when used in combination with phosphorodiamidate morpholino oligomers (PMO) in both myoblasts and myotubes. Guanine and its analogues were unable to induce detectable skipping of exon 23 when used alone but enhanced PMO-induced exon skipping significantly (approximately two times) in the muscles of dystrophic mdx mouse in vivo. Our results demonstrate that small-molecule compounds could enhance specific exon skipping synergistically with antisense oligomers for experimental therapy to human diseases.

Long-term (12-year) aorta-specific survival after on-label endovascular repair of degenerative descending thoracic aneurysms in nonsyndromic patients is excellent (96%) with sustained protection from rupture, and a low rate of reintervention owing to endoleak (7%). Endovascular repair should be considered the treatment of choice for this pathology.

This study objectively determines the optimal timing of adjuvant chemotherapy for patients with resected colon cancer. Delay beyond 6 weeks is associated with compromised survival. These findings emphasize the importance of the timely initiation of therapy, and suggest that efforts to enhance recovery following surgery have the potential to improve survival by decreasing delay to adjuvant chemotherapy.