Membrane systems for bioartificial organs and regenerative medicine

Health care requests for patients with tissue loss or end-stage organ failure are increasing due to the worldwide population aging and the development of pathologies related to organ functions. Transplantation represents the gold standard of lifesaving but is limited by the scarce availability of donor organs, and as a consequence, there has been a growing demand for biological substitutes that are able to restore or to maintain temporarily or improve organ functions. In the last decades advances in biomaterials have generated a range of materials and devices for use either outside the body or through implantation to replace or assist functions which may have been lost through disease or injury, providing a bridge to recovery or transplantation. Membrane processes play a pivotal role in the replacement therapy for acute and chronic organ failure diseases. In fact, all current extracorporeal blood purification and oxygenation methods employ membranes. In these devices membranes act as selective barriers for the removal of endogenous and exogenous toxins from the patient's blood (hemodialysis, hemofiltration, etc.) or for gas exchange with blood (blood oxygenation). Membrane technology offers new, interesting opportunities for the design of bioartificial organs such as the bioartificial liver, pancreas, kidney, or lung. The use of polymeric semipermeable membranes with different physico-chemical and transport properties is appealing in the creation of a bioartificial organ since these and biomembranes share similarities such as the selective transport of molecules, resistances, and protection. Furthermore, synthetic membranes can easily be mass produced, modulating their morphological and physico-chemical properties for a specific organ or tissue. Membranes must be designed to replicate the properties of the extracellular matrix providing structural support to the cells, which are the functional elements of any tissue or organ. In this context the bioreactor technology plays a pivotal role in the regeneration and in the production of individualized biological implants. The bioreactor, through the fluid dynamics modulation, may simulate the in vivo complex physiological environment ensuring an adequate mass transfer of nutrients and metabolites and the molecular and mechanical regulatory signals. This technology leads to the fabrication of bioartificial organs that are functionallymatched to human organs and can be used for clinical organ transplantation. Membrane Systems: For Bioartificial Organs and Regenerative Medicine reviews the latest developments in membranes and investigates how they can be used to improve the quality and efficiency of bio/artificial organs. The book highlights the design and development of membranes to be used in bio/artificial organs starting from the polymers to the preparation, characterization, and sterilization procedures to be used. Basic issues in membrane separation for biomedical devices such as membrane transport, concentration polarization, and fouling phenomena are specifically discussed. The bioengineering principles, the different strategies pursued for the development of membrane bio/artificial organs including important issues related to blood- and cell-membrane interactions are described with the aim of opening new and exciting frontiers in the next decades. The use of membrane processes and devices can be exciting in helping to find nature's substitutes and to solve the pathogenesis of important human diseases while proposing new and fascinating medical therapies.