Manual on the proper use of the 211At-labeled PSMA ligand ([211At]PSMA-5) for clinical trials of targeted alpha therapy (1st edition)

The version of record of this article, first published in Annals of Nuclear Medicine, is available online at Publisher’s website: https://doi.org/10.1007/s12149-024-01916-6.Recently, an astatine-labeled prostate-specific membrane antigen (PSMA) ligand ([211At]PSMA-5) has been developed for the targeted alpha therapy of patients with prostate cancer. This manual delineates its physicochemical characteristics to assist healthcare professionals in understanding the α-ray-emitting drug of [211At]PSMA-5 when administered to patients. The safety considerations regarding the handling and use of this drug in clinical trials are outlined, based on the proper usage manual of previous studies. The dose limits, as defined by the guidelines of the International Commission on Radiological Protection (ICRP) and the International Atomic Energy Agency (IAEA), are assessed for patients’ caregivers and the general public. According to the calculations provided in this manual, clinical trials involving [211At]PSMA-5 can be safely conducted for these populations even if patients are released after its administration. Moreover, this manual provides comprehensive guidance on the handling of [211At]PSMA-5 for healthcare facilities, and compiles a list of precautionary measures to be distributed among patients and their caregivers. While this manual was created by a research team supported by Ministry of Health, Labour, and Welfare in Japan and approved by Japanese Society of Nuclear Medicine, its applicability extends to healthcare providers in other countries. This manual aims to facilitate conducting clinical trials using [211At]PSMA-5 in patients with prostate cancer

Immortalization of Human Fetal Cells: The Life Span of Umbilical Cord Blood-derived Cells Can Be Prolonged without Manipulating p16(INK4a)/RB Braking Pathway

Human umbilical cord blood-derived mesenchymal stem cells (UCBMSCs) are expected to serve as an excellent alternative to bone marrow-derived human mesenchymal stem cells. However, it is difficult to study them because of their limited life span. To overcome this problem, we attempted to produce a strain of UCBMSCs with a long life span and to investigate whether the strain could maintain phenotypes in vitro. UCBMSCs were infected with retrovirus carrying the human telomerase reverse transcriptase (hTERT) to prolong their life span. The UCBMSCs underwent 30 population doublings (PDs) and stopped dividing at PD 37. The UCBMSCs newly established with hTERT (UCBTERTs) proliferated for >120 PDs. The p16(INK4a)/RB braking pathway leading to senescence can be inhibited by introduction of Bmi-1, a polycomb-group gene, and human papillomavirus type 16 E7, but the extension of the life span of the UCBMSCs with hTERT did not require inhibition of the p16(INK4a)/RB pathway. The characteristics of the UCBTERTs remained unchanged during the prolongation of life span. UCBTERTs provide a powerful model for further study of cellular senescence and for future application to cell-based therapy by using umbilical cord blood cells

Prevention of Ornithine Cytotoxicity by Nonpolar Side Chain Amino Acids in Retinal Pigment Epithelial Cells

PURPOSE. To investigate the effect of amino acids on ornithine cytotoxicity in ornithine-␦-aminotransferase (OAT)-deficient human retinal pigment epithelial (RPE) cells as an in vitro model of gyrate atrophy (GA) of the choroid and retina. METHODS. RPE cells were treated with 0.5 mM 5-fluoromethylornithine (5-FMOrn), a specific and irreversible OAT inhibitor. OAT-deficient RPE cells were incubated with 10 mM ornithine in the presence of 20 mM of 1 of 18 amino acids or 10 mM 2-amino-2-norbornane-carboxylic acid (BCH), a conventional inhibitor of the amino acid transporter system L. Ornithine cytotoxicity and cytoprotective effects of each amino acid was evaluated with a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) colorimetric assay 72 hours after treatment with ornithine in OAT-deficient RPE cells. Ornithine incorporation into RPE cells was evaluated using DL discovered that the biochemical abnormalities of this disorder are hyperornithinemia and overflow ornithinuria. Further, the finding of an association between hyperornithinemia and GA led to the discovery of an enzyme defect, a deficiency of the mitochondrial matrix enzyme ornithine-␦-aminotransferase (OAT). 3-5 We have reported that inactivation of OAT in human retinal pigment epithelial (RPE) cells by 5-fluoromethylornithine (5-FMOrn), a specific irreversible inhibitor of OAT, 6 makes them susceptible to ornithine, leading to cell death. 7 A human hepatoma cell line, HepG2, and a fibroblast cell line, WI-38, which possess OAT activity comparable to that of RPE cells, are not affected by ornithine when OAT is inactivated by 5-FMOrn, suggesting that ornithine cytotoxicity toward 5-FMOrn-treated RPE can be used as an in vitro model of GA. We have also demonstrated that proline prevents ornithine-induced cell death. Mammalian cells have two biosynthetic pathways for proline and share a common intermediate, L-⌬ 1 -pyrroline-5-carboxylic acid (P5C), which is formed from ornithine by OAT and from glutamic acid by P5C synthase. In a previous study, ornithine almost completely blocked P5C synthase and decreased the incorporation of proline derived from glutamic acid into protein in fibroblasts cultured from patients with GA 8 ; however, the mechanisms of ornithine cytotoxicity in OAT-deficient RPE cells and cytoprotection by proline remain to be elucidated. In the course of our earlier experiments, we noticed that 5-FMOrn-treated RPE cells are damaged by ornithine when cultured in Ham F12 medium, whereas they are not affected by ornithine in Dulbecco's modified Eagle's (DME) medium devoid of proline. Those unexpected results prompted us to investigate the effect of other amino acids on ornithine cytotoxicity and incorporation of ornithine in human RPE cells to clarify the mechanisms of ornithine cytotoxicity. From the present results, we report that most of the nonpolar and uncharged polar side chain amino acids tested prevented ornithine cytotoxicity through L-type amino acid transporters. MATERIAL AND METHODS Cell Culture A human RPE cell line, hTERT-RPE, previously established by gene transfer of human telomerase reverse transcriptase cDNA, 9 was kindly provided by Donald J. Zack (Wilmer Ophthalmological Institute, Johns Hopkins University, Baltimore, MD). This RPE cell line has been reported to have several characteristics of other normal RPE cells, such as an expression of Rpe65 and in vitro differentiation capacity. From the Departments of 1 Ophthalmology an