Regenerative medicine in neurological field
The lesions of the central nervous system and neurodegenerative diseases constitute one of the major challenges for moderrn medicine, for the modest capacity autoriparativa of nerve tissue and for the absence of causal therapies for neurodegenerative diseases. In recent years, has been published a large number of studies on the possibility to use different cell types in different experimental models, but the picture that emerges with respect to the possible use of cellular therapies for diseases of the CNS is largely inconsistent (Aboody et al ., 2011; Walker et al., 2010). It ‘clear that the’ homing and the lodging are key points are for administration of cells in the CNS.
In fact, only a very small percentage of cells that were administered by intrathecal or intravenous intraparenchymal are found at the sites of injury (Chen et al., 2011). In addition, the numerous studies on cellular transplants in several animal models and human studies have indicated that a very low number of transplanted cells remain permanently in the tissue and differ in the desired phenotype (Shichinohe et al., 2004; Sykova et al. 2006; Prabhakar et al., 2010; Zhang et al., 2010; Cicchetti et al., 2011). In these cases the effectiveness is attributed to the paracrine properties of transplanted cells (Ratajczak et al., 2011; Schira et al., 2011). In fact, recent studies suggest that the paracrine effect of factors secreted rather than direct cell replacement are responsible for most of the benefits observed after cell transplantation (Shimada and Spees, 2011).
There is therefore a growing interest in technologies that are able to orient and keep the cells on the target, which may control the communication host-cells and that they can control and stabilize the cellular properties. At the same time, the technologies of tissue engineering are offering a wide field of possibilities to design devices tailored depending on the type of trauma, of its extension, the area concerned etc (Walker et al., 2009; Han et al. 2010; Zurita et al., 2010; Jurga et al., 2011). The use of polymers and nanotechnology for the repair and reconstruction of SN regards nanostructured scaffolds for example, used to restore an appropriate neural architecture, in order to restore the cell-cell communication, cell-ECM.
The conjugation of the scaffolds with components of the ECM (es ac. Hyaluronic acid, a natural glycosaminoglycan) has been proposed for example to adjust locally immune reactions and inflammatory processes (Mizrahy et al., 2011) and to promote nerve regeneration (Park et al. , 2009). These devices produced by electrospinning of biocompatible and biodegradable chemicals are showing promise for directing axonal growth, create niches of stem cells and precursors; promote neural lineage or oligodendroglial; carry and to recruit cells in a desired area (Jiang et al., 2012; Borgens and Cho, 2012). Soft scaffolds generated both by electrospinning of materials of different nature and synthesis or shaped by soft lithography to mime the topography of the surface and mechanical consistency of ECM, may also be conjugated to molecules of ECM or to drugs that act on multiple lineages, adapted to maintain cells on a surface, or to include cells in a pocket, etc., thus allowing a wide variety of “smart devices” designed for specific pathological conditions.