ORIGINAL ARTICLE Efficient transduction of healthy and malignant plasma cells by lentiviral vectors pseudotyped with measles virus glycoproteins M Schoenhals 1 , C Frecha 2,3,4 , A Bruyer 1 , A Caraux 1 , JL Veyrune 5 , M Jourdan 1 , J Moreaux 1,5 , F-L Cosset 2,3,4 , E Verhoeyen 2,3,4 and B Klein 1,5,6 A lot of genes deregulated in malignant plasma cells (PCs) involved in multiple myeloma have been reported these last years. The expression of some of these genes is associated with poor survival. A critical step is to elucidate the biological mechanisms triggered by these gene products. Such studies are hampered by the difficulty to obtain malignant PCs and to genetically modify them. Usual lentiviral vectors (LVs) pseudotyped with vesicular stomatitis virus envelope glycoprotein poorly transduced healthy and malignant PCs. Here, we report that LVs pseudotyped with the hemagglutinin and fusion glycoproteins from the measles Edmonston strain (H/F-LVs) can efficiently and stably transduce healthy and primary malignant PCs, without modifying their main phenotypic characteristics. Both LV pseudotypes efficiently transduced human myeloma cell lines. Importantly, both healthy and malignant PCs expressed CD46 and SLAMF1/CD150 membrane proteins, which are critical receptors for binding and productive genetic modification by H/F-LVs. The ability to efficiently introduce and express a given gene into PCs opens the possibility to study in detail PC biology. Leukemia (2012) 26, 1663--1670; doi:10.1038/leu.2012.36 Keywords: plasma cell; transduction; multiple myeloma; measles glycoproteins INTRODUCTION Multiple myeloma (MM) is characterized by the accumulation of malignant plasma cells (PCs), primarily in the bone marrow. 1 Normal PCs are rare cells in the body, located mainly in the bone marrow (0.5% of bone marrow cells) and mucosa. These normal PCs are quiescent cells in vivo and may survive for years, insuring long-term humoral memory. 2 MM disease is preceded by a several year-lasting premalignant monoclonal gammopathy with unde- termined significance (MGUS). 3 MGUS may transform to MM with a 1% rate per year, independent on MGUS duration. 4 MM disease is heterogeneous in terms of molecular abnormalities in malignant PCs, 5 and the use of high throughput methodologies has revealed many genes whose copy number or expression is associated with a difference in patients’ treatment response or survival. But the study in depth of the biological role played by deregulated gene products is hampered by the availability of primary healthy or malignant PCs, the difficulty to culture and/or to genetically modify them. This is particularly the case when no tools (recombinant protein or inhibitor) exist to study the function of a gene product. This explains why most biological studies use human myeloma cell lines (HMCLs), which are obtained form a minority of patients with a special MM disease entity, that is, patients with extramedullary proliferation. 6 The biological con- cepts obtained with these HMCLs could be limited to this minority of patients, in whom malignant PCs are no more or less dependant on the bone marrow environment, likely due to additional deregulations of survival and cell cycle. 7 To further progress in the understanding of MM disease, it is critical to be able to stably introduce a genetic modification into malignant PCs to get a forced expression or knockdown of a gene. It is also important to manipulate PCs, to investigate whether myeloma genes can modify the biology of healthy PCs and transform them into premalignant or malignant PCs. Whereas vesicular stomatitis virus G (VSV-G) pseudotyped lentiviral vectors (LVs) can transduce HMCLs, 8 they poorly transduce primary malignant PCs, which are weakly cell cycling. We have shown recently that LVs incorporating the Edmonston strain measles virus (MV) with hemagglutinin and fusion glycoproteins (H/F-LVs) can efficiently and stably transduce quiescent human B lymphocytes 9 or T lymphocytes. 10 The MV H glycoprotein binds to signaling lymphocyte activation molecule (SLAMF1/CD150) and to CD46, which are expressed on a subpopulation of quiescent B or T lymphocytes. Transduction of malignant PCs by H/F-LVs should be possible as several reports have documented the ability of oncolytic MV to efficiently infect and kill primary malignant PCs or HMCLs, in particular because malignant PCs express CD46, and this strategy was proposed as a therapeutic option to kill malignant PCs. 11 - 13 In this study, we report that H/F-LVs can efficiently transduce primary malignant PCs as well as healthy PCs, where VSV-G-LVs failed. VSV-G-LVs can transduce HMCLs but with a lower efficacy than MV-LVs. MATERIALS AND METHODS Cell samples Bone marrow cells were obtained from 10 patients with MM for routine clinical evaluation of the disease. Excess cells were used after obtaining patients’ written informed consent in accordance with the Declaration of Helsinki and agreement of the Center for Biological Resources of Received 19 September 2011; revised 28 December 2011; accepted 25 January 2012; accepted article preview online 9 February 2012; advance online publication, 2 March 2012 1 INSERM U1040, Institute for Research in Biotherapy, CHU Montpellier, Hospital St Eloi, Montpellier, France; 2 INSERM, U758, Human Virology Department, EVIR, Lyon, France; 3 Ecole Normale Supe ´rieure de Lyon, Lyon, France; 4 Universite ´ de Lyon, UCB-Lyon1, Lyon, France; 5 CHU Montpellier, Institute of Research in Biotherapy, Montpellier, France and 6 Universite ´ MONTPELLIER1, UFR Me ´ decine, Montpellier, France. Correspondence: Professor B Klein, INSERM U1040, Institute for Research in Biotherapy, CHU Montpellier, Hospital St Eloi , Av Augustin Fliche, Montpellier 34295, France. E-mail: bernard.klein@inserm.fr Leukemia (2012) 26, 1663 - 1670 & 2012 Macmillan Publishers Limited All rights reserved 0887-6924/12 www.nature.com/leu