Lentiviral standards to determine the sensitivity of assays that quantify lentiviral vector copy numbers and genomic insertion sites in cells

With an increasing number of gene therapy clinical trials and drugs reaching the market, it becomes important to standardize the methods that evaluate the efficacy and safety of gene therapy. We herein report the generation of lentiviral standards which are stable, cloned human cells prepared from the diploid HCT116 cell line and which carry a known number of lentiviral vector copies in their genome. These clones can be used as reference cellular materials for the calibration or qualification of analytical methods that quantify vector copy numbers in cells (VCN) or lentiviral vector genomic integration sites (IS). Cellular standards were used to show the superior precision of digital droplet PCR (ddPCR) over quantitative PCR (qPCR) for VCN determination. This enabled us to develop a new sensitive and specific VCN ddPCR method specific for the integrated provirus and not recognizing the transfer plasmid. The cellular standards, were also useful to assess the sensitivity and limits of a ligation-mediated PCR (LM-PCR) method to measure IS showing that at least 1% abundance of a single IS can be detected in a polyclonal population but that not all IS can be amplified with similar efficiency. Thus, lentiviral standards should be systematically used in all assays that assess lentiviral gene therapy efficacy and safety.

Preclinical Development of an AAV8-hUGT1A1 Vector for the Treatment of Crigler-Najjar Syndrome

Adeno-associated viruses (AAVs) are among the most efficient vectors for liver gene therapy. Results obtained in the first hemophilia clinical trials demonstrated the long-term efficacy of this approach in humans, showing efficient targeting of hepatocytes with both self-complementary (sc) and single-stranded (ss) AAV vectors. However, to support clinical development of AAV-based gene therapies, efficient and scalable production processes are needed. In an effort to translate to the clinic an approach of AAV-mediated liver gene transfer to treat Crigler-Najjar (CN) syndrome, we developed an (ss)AAV8 vector carrying the human UDP-glucuronosyltransferase family 1-member A1 (hUGT1A1) transgene under the control of a liver-specific promoter. We compared our construct with similar (sc)AAV8 vectors expressing hUGT1A1, showing comparable potency in vitro and in vivo. Conversely, (ss)AAV8-hUGT1A1 vectors showed superior yields and product homogeneity compared with their (sc) counterpart. We then focused our efforts in the scale-up of a manufacturing process of the clinical product (ss)AAV8-hUGT1A1 based on the triple transfection of HEK293 cells grown in suspension. Large-scale production of this vector had characteristics identical to those of small-scale vectors produced in adherent cells. Preclinical studies in animal models of the disease and a good laboratory practice (GLP) toxicology-biodistribution study were also conducted using large-scale preparations of vectors. These studies demonstrated long-term safety and efficacy of gene transfer with (ss)AAV8-hUGT1A1 in relevant animal models of the disease, thus supporting the clinical translation of this gene therapy approach for the treatment of CN syndrome.

[Nebulisation in childhood asthma]

The inhaled route way, which directly brings an appropriate amount of drug in the right place, is at the present time the recommended route for asthma treatments. The development of spacer devices, easier to use, has reduced the indications of nebulised treatments, but these are still essential in some situations. Nebulisation of short acting beta-2-agonists, which usually requires oxygen administration, is still the first line treatment of a severe acute asthma attack. Ipratropium bromide can be added in the nebulisation, depending on the severity of the attack and the response to beta-2-agonists. Sodium cromoglycate is not used in the prophylactic treatment of childhood asthma any more, but nebulised budesonide is still very useful in moderate to severe persistent asthma in children under 5 years of age, after failure of a treatment with a spacer device. The quality of nebulisation is fully dependent on the equipment used, and on the practical conditions of its realization. It is of most extreme importance to use a compressor/nebulizer couple which is validated for the delivered drug, and that the child breathes, depending on age, via a mouth peace or a facial mask.

[The asthmatic child at school: difficulties encountered and proposed solutions]

Among a child out of ten is asthmatic. School absenteeism is frequent, due to an insufficient control of asthma. This insufficient control is especially evident at school where the usual risk factors of asthma are present. Allergenic risk with animals danders carried by other children, or regular practice of sports, are difficult situations for the asthmatic child. Controlling asthma, informing school and communicating with teachers, using the individualized care project, should avoid this absenteeism, which is responsible of school backwardness and difficulties in choosing careers.

Reexamination of hemocytes in brine shrimp (Crustacea, branchiopoda)

In 1941, a single type of hemocyte was described in the blood of the brine shrimp Artemia salina using light microscopy. This condition is unusual because most crustaceans examined using morphological, cytochemical, and functional methods have at least two types of hemoctyes. Upon examining A. franciscana, we found a single type of disk-shaped hemocyte, with a centrally located nucleus and about 15 large (6 microm diameter) granules. The granules stain for the presence of acid phosphatase and react with L-DOPA suggesting, respectively, that they are involved in degrading ingested material and possess the phenoloxidase system. Hemocytes require calcium for adhesion, bind together to mend small wounds in the body wall, and are able to phagocytose bacteria. Blood cells of A. franciscana are morphologically and functionally similar to those of the primitive chelicerate, Limulus polyphemus, and both forms have apparently given rise to more advanced taxa with multiple types of hemocytes. The major difference between the two species is the presence of the phenoloxidase system in the Crustacea and its apparent absence in the chelicerates.

Nonspecific suppressive and cytostatic activities mediated by human colonic carcinoma tissue or cultured cell extract

We have previously shown that soluble extracts from human colonic carcinoma (SCE) were potent inhibitors of the PHA-induced DNA synthesis of normal allogeneic peripheral lymphocytes. From the present study, SCE appeared to have a broad and nonspecific range of activity. The SCE-suppressive effect was observed whatever the lymphoid organ or the animal species used as a source of stimulated lymphocytes. Moreover, we always obtained a complete inhibition of the lymphoproliferative response to all tested mitogens including PHA, Con A, PWM, and, for animal lymphocytes, LPS. In addition to the suppressive activity on lymphocytes, SCE also inhibited proliferation of cultured human CCL6 embryonic intestine cells and HT29 colonic carcinoma cells, and of cultured rat fibrosarcoma cells. Soluble extracts from HT29 cells (SCCE) were able to mimic the nonspecific suppressive and cytostatic activities of SCE. The suppressive activity was also found in extracts from hepatic metastases (SHME) of a primary colonic tumor. In contrast, soluble extracts from normal liver or nonmalignant colonic mucosa did not interfere with cell proliferation. These data suggest that both SCE and SCCE contain molecular components(s) that can inhibit a wide variety of proliferating cells, including stimulated lymphocytes.