Tae Matsumoto

Prolonged Survival and Phenotypic Correction of Akp2 / Hypophosphatasia Mice by Lentiviral Gene Therapy

Hypophosphatasia (HPP) is an inherited systemic skeletal disease caused by mutations in the gene encoding the tissue‐nonspecific alkaline phosphatase (TNALP) isozyme. The clinical severity of HPP varies widely, with symptoms including rickets and osteomalacia. TNALP knockout (Akp2−/−) mice phenotypically mimic the severe infantile form of HPP; that is, TNALP‐deficient mice are born with a normal appearance but die by 20 days of age owing to growth failure, hypomineralization, and epileptic seizures. In this study, a lentiviral vector expressing a bone‐targeted form of TNALP was injected into the jugular vein of newborn Akp2−/− mice. We found that alkaline phosphatase activity in the plasma of treated Akp2−/− mice increased and remained at high levels throughout the life of the animals. The treated Akp2−/− mice survived for more than 10 months and demonstrated normal physical activity and a healthy appearance. Epileptic seizures were completely inhibited in the treated Akp2−/− mice, and X‐ray examination of the skeleton showed that mineralization was significantly improved by the gene therapy. These results show that severe infantile HPP in TNALP knockout mice can be treated with a single injection of lentiviral vector during the neonatal period.

Rescue of severe infantile hypophosphatasia mice by AAV-mediated sustained expression of soluble alkaline phosphatase.

Hypophosphatasia (HPP) is an inherited disease caused by a deficiency of tissue-nonspecific alkaline phosphatase (TNALP). The major symptom of human HPP is hypomineralization, rickets, or osteomalacia, although the clinical severity is highly variable. The phenotypes of TNALP knockout (Akp2(-/-)) mice mimic those of the severe infantile form of HPP. Akp2(-/-) mice appear normal at birth, but they develop growth failure, epileptic seizures, and hypomineralization and die by 20 days of age. Previously, we have shown that the phenotype of Akp2(-/-) mice can be prevented by enzyme replacement of bone-targeted TNALP in which deca-aspartates are linked to the C-terminus of soluble TNALP (TNALP-D10). In the present study, we evaluated the therapeutic effects of adeno-associated virus serotype 8 (AAV8) vectors that express various forms of TNALP, including TNALP-D10, soluble TNALP tagged with the Flag epitopes (TNALP-F), and native glycosylphosphatidylinositol-anchored TNALP (TNALP-N). A single intravenous injection of 5×10(10) vector genomes of AAV8-TNALP-D10 into Akp2(-/-) mice at day 1 resulted in prolonged survival and phenotypic correction. When AAV8-TNALP-F was injected into neonatal Akp2(-/-) mice, they also survived without epileptic seizures. Interestingly, survival effects were observed in some animals treated with AAV8-TNALP-N. All surviving Akp2(-/-) mice showed a healthy appearance and a normal activity with mature bone mineralization on X-rays. These results suggest that sustained alkaline phosphatase activity in plasma is essential and sufficient for the rescue of Akp2(-/-) mice. AAV8-mediated systemic gene therapy appears to be an effective treatment for the infantile form of human HPP.

Successful Gene Therapy In Utero For Lethal Murine Hypophosphatasia

Hypophosphatasia (HPP), caused by mutations in the gene ALPL encoding tissue-nonspecific alkaline phosphatase (TNALP), is an inherited systemic skeletal disease characterized by mineralization defects of bones and teeth. The clinical severity of HPP varies widely, from a lethal perinatal form to mild odontohypophosphatasia showing only dental manifestations. HPP model mice (Akp2(-/-)) phenotypically mimic the severe infantile form of human HPP; they appear normal at birth but die by 2 weeks of age because of growth failure, hypomineralization, and epileptic seizures. In the present study, we investigated the feasibility of fetal gene therapy using the lethal HPP model mice. On day 15 of gestation, the fetuses of HPP model mice underwent transuterine intraperitoneal injection of adeno-associated virus serotype 9 (AAV9) expressing bone-targeted TNALP. Treated and delivered mice showed normal weight gain and seizure-free survival for at least 8 weeks. Vector sequence was detected in systemic organs including bone at 14 days of age. ALP activities in plasma and bone were consistently high. Enhanced mineralization was demonstrated on X-ray images of the chest and forepaw. Our data clearly demonstrate that systemic injection of AAV9 in utero is an effective strategy for the treatment of lethal HPP mice. Fetal gene therapy may be an important choice after prenatal diagnosis of life-threatening HPP.

Successful gene therapy in utero for lethal murine hypophosphatasia.

Hypophosphatasia (HPP), caused by mutations in the gene ALPL encoding tissue-nonspecific alkaline phosphatase (TNALP), is an inherited systemic skeletal disease characterized by mineralization defects of bones and teeth. The clinical severity of HPP varies widely, from a lethal perinatal form to mild odontohypophosphatasia showing only dental manifestations. HPP model mice (Akp2(-/-)) phenotypically mimic the severe infantile form of human HPP; they appear normal at birth but die by 2 weeks of age because of growth failure, hypomineralization, and epileptic seizures. In the present study, we investigated the feasibility of fetal gene therapy using the lethal HPP model mice. On day 15 of gestation, the fetuses of HPP model mice underwent transuterine intraperitoneal injection of adeno-associated virus serotype 9 (AAV9) expressing bone-targeted TNALP. Treated and delivered mice showed normal weight gain and seizure-free survival for at least 8 weeks. Vector sequence was detected in systemic organs including bone at 14 days of age. ALP activities in plasma and bone were consistently high. Enhanced mineralization was demonstrated on X-ray images of the chest and forepaw. Our data clearly demonstrate that systemic injection of AAV9 in utero is an effective strategy for the treatment of lethal HPP mice. Fetal gene therapy may be an important choice after prenatal diagnosis of life-threatening HPP.

Solid and cystic tumor of the pancreas in a 12‐year‐old boy

Solid and cystic tumor of the pancreas (SCT) was first described by Frantz as a papillary tumor in 1959. 1 Kloppel et al. subsequently proposed that this tumor originated from acinar cells and described it as a solid and cystic acinar cell tumor. 2 Clinically, this tumor is usually observed in adolescent girls or young women and the main symptoms are an abdominal mass either with or without abdominal pain. 3 In most cases, hematologic and biochemical examination show no abnormalities. Although prognosis following complete tumor resection is generally good, complications, such as distant metastasis and pancreatic invasion, occur in some cases. 4 In the present report we describe a case of a 12-yearold boy with solid and cystic tumor of the pancreas, which was difficult to diagnose definitively before surgery.

Somatic mosaicism in MYH9 disorders: the need to carefully evaluate apparently healthy parents

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