Positive reaction to safer blood Quality-controlled production of human blood in bioreactors is a goal now in. The same project findings are also applicable to the production of human organs in vitro. Background Producing blood in bioreactors under carefully controlled conditions could be a solution to man... Quality-controlled production of human blood in bioreactors is a goal now in. The same project findings are also applicable to the production of human organs in vitro. Background Producing blood in bioreactors under carefully controlled conditions could be a solution to many healthcare problems in the EU, including the shortage of blood for medical purposes and the need to screen donor blood to minimise the risk of transmitting a pathogen to the recipient. The European Commission's Biotech 2 project `Hematopoietic bioreactor: a model for human somatic stem cell culture' has overcome several obstacles on the way to achieving this goal. Its findings, which apply to somatic stem cells in general, and have many potential applications. Description, impact and results Hematopoietic stem cells are precursors of mature blood cells, stored in the bone marrow in a `resting state'. Before culturing them, the project partners had to understand what causes the resting state. They identified several inhibitors of cell division and, by blocking these, allowed the stem cells to divide. This technique removes an obstacle to the use of somatic stem cells in gene therapy: the viral vectors used to carry a therapeutic gene into target cells can deliver their payload only to dividing cells. In the first cultures, the stem cells differentiated too quickly, and completely disappeared within 15 days. This problem has been solved and cells can now be grown for three months through the continuous maintenance of an undifferentiated stem-cell pool. Four patents have been filed in this area. Remarkably, the project findings also apply to other somatic stem cells (liver-, skin-cell precursors, etc.). It is even possible to grow several kinds of stem cells together to produce an organ such as skin, with its different layers and specialised cells. Furthermore, stem cells express a gene responsible for preventing cell ageing. They can be modified either to over-express or not to express this gene at all, and thus provide a tool for studying the ageing process. More generally, they can be genetically engineered for the study of genes of unknown function. In medicine, applications include abundant, safe blood or better skin for the severely burned. In vitro-grown organs are also potential tools for toxicology studies and for testing medicines, cosmetics, etc. For all these applications, it would be even better to use embryonic stem cells (derived from the supernumerary embryos obtained by in vitro fertilisation) as they do not differentiate spontaneously in culture, so much greater quantities can be obtained. But, their use is banned in some countries. In the current biomedical ethics debate, their great potential contribution to human health, in the production of in vitro tissues and organs, must be acknowledged and, contrary to popular belief, they cannot be implanted in a uterus to produce human clones! Working partnerships The project team includes cell biologists and industrial partners. Clinical and regulatory testing of the blood and tissues are beyond the scope of the project.
