This special issue of Gene Therapy contains review articles contributed by speakers of the Second European Conference & Practical Course: Towards clinical Gene Therapy: preclinical gene transfer assessment, held at the Facultat de Veterinària, Universitat Autònoma de Barcelona (UAB) in Bellaterra (Spain) on February 1–14, 2004. This event was the second of a series of training initiatives on gene and cell therapy that Généthon is developing with other European centres involved in this domain.

Started in 2002 with the first Eurolabcourse on vectorology (Evry, 14–26 April), this project continued in 2004 with the Conference & Course in Bellaterra and the 3rd Conference & Course on industrial development of vectors, held in Evry during 14–26 June 2004 (see the list of past and future events at www.vecteurotrain.org). Such educational activity addresses a need of the scientific community, since about 150 researchers coming from different institutions of many EU and non-EU countries participated in each event.

The success of the Conference & Course in Bellaterra was also due to the new training format, which combined the typical research conference (including invited lectures, short communications and poster sessions) with a round table discussion and a practical course. After the basic techniques of vector production, purification and characterisation delivered with the first Eurolabcourse in 2002 in Evry, we thought it necessary to train on the basic techniques of gene transfer in vivo into animals, which is the second essential step in gene therapy development. Therefore, lectures, short communications and posters on principles of gene delivery into different organs (including gene expression assessment in live animals and the immune response) were followed by a practical training on gene delivering in vivo, that is, administration into liver, lung, brain and muscle.

In this first course on pre-clinical gene transfer, theoretical and practical issues of gene vectors as potential new bio-pharmaceuticals have been presented. For the first time, 32 researchers from 18 countries were trained on the techniques of in vivo gene transfer according to the criteria of good laboratory practices and ethical principles of animal experimentation.

The articles reflect the most relevant topics developed during the Conference (1–5 February), namely, (a) the best vectors in terms of balance between therapeutic benefit and adverse effects, and how to deliver them into liver, lung, inner hear, skin, retina and muscle; (b) assessment of gene expression directly in the organs of live animals by using imaging-based analysis; (c) factors and mechanisms underlying the immune response against gene vectors, and how to modulate it in cancer therapy; (d) the use of foetal gene therapy approach to circumvent the natural barriers towards gene transfer in adult animals; (e) the ethical issues of animal experimentation.

The articles are followed by the abstracts of communications as they were in the conference book. Among these, one more abstract has been added resuming some scientific, technological and regulatory aspects of clinical trials and the gene therapy development process that were discussed in the round table on 3rd February.

Therefore, this supplement of Gene Therapy will disseminate the scientific results of the Conference & Course in Bellaterra to the whole scientific community in order to stimulate discussion and exchanges, and implement thus the gene therapy development process in Europe.

We wish to thank all persons and institutions below, who actively participated in achieving the Second European Conference and Course in Bellaterra:

1. The organisers:
   • UAB: Miguel Chillon, Assumptió Bosch, Fàtima Bosch and Merce Monfar
   • GENETHON: Patrick Gonin, Corinne Laplace, Otto Merten and Daniel Stockholm
2. The Scientists who supervised the scientific programme and reviewed the applications of candidates to participate in practical course
   • Directory Board: François-Loïc Cosset (Lyon, France), Olivier Danos (Evry, France), Fulvio Mavilio (Modena, Italy), Edward Smith (Huddinge, Sweden), Didier Trono (Geneva, Switzerland)
   • Selection Committee: Alessandro Aiuti (Milan, Italy), Annick Branderburger (Gosselies, Belgium), Dider Caizergues (Evry, France), Miguel Chillon (Bellaterra, Spain), Christophe Delenda (Evry, France), Anne-Marie Douar (Evry, France), Hüseyin Firat (Basel, Switzerland), Patrick Gonin (Evry, France), Antoine Kichler (Evry, France), Eric Kremer (Montpellier, France), Pierre Lehn (Paris, France), Otto Merten (Evry, France), Jean-Christophe Pages (Tours, France), Amos Panet (Jerusalem, Israel), Hélène Pollard (Evry, France), Jean Rommelaere (Heidelberg, Denmark), Liliane Tenenbaum (Brussels, Belgium)
3. The sponsors for their contribution to the achievement of the event with financial support or materials:
   • Public Institutions: European Commission (EC, Brussels, Belgium, contract no. LSSB-CT-2003-503219), Federation of European Biochemical Societies (FEBS, London, UK, grant no. 04-12C), Institut National de la Santé et Recherche Médicale (INSERM, Paris, France), Centre National de la Recherche Scientifique (CNRS, Paris, France), Institució Catalana de Recerca i Estudis Avançats (ICREA, Barcelona, Spain), GENOPOLE (Evry, France)
   • Industries: Baxter R&D Europe SCRL (Nivelles, Belgium), Charles River Laboratories (Les Oncins, France), Harlan France SARL (Gannat, France), IGEA, SRL (Carpi, Italy), IZASA, SA (Madrid, Spain), Servei Microscòpia (Barcelona, Spain), Plasmid Factory Gmbh (Bielefeld, Germany), NUCLIBER (Madrid, Spain).