Nanotechnology for regenerative medicine Dongwoo Khang & Joseph Carpenter & Young Wook Chun & Rajesh Pareta & Thomas J. Webster # Springer Science + Business Media, LLC 2008 Abstract Future biomaterials must simultaneously enhance tissue regeneration while minimizing immune responses and inhibiting infection. While the field of tissue engineering has promised to develop materials that can promote tissue regeneration for the entire body, such promises have not become reality. However, tissue engineering has experienced great progress due to the recent emergence of nanotechnol- ogy. Specifically, it has now been well established that increased tissue regeneration can be achieved on almost any surface by employing novel nano-textured surface features. Numerous studies have reported that nanotechnology accelerates various regenerative therapies, such as those for the bone, vascular, heart, cartilage, bladder and brain tissue. Various nano-structured polymers and metals (alloys) have been investigated for their bio (and cyto) compatibility properties. This review paper discusses several of the latest nanotechnology findings in regenerative medicine (also now called nanomedicine) as well as their relative levels of success. Keywords Nanotechnology . Tissue engineering . Orthopedic . Vascular . Neural . Skin . Cellular and protein interactions 1 Introduction Tissue cells elicit specific, distinct reactions depending on implant surface structures (Stevens and George 2005). The majority of conventional biomaterials possess micron scale or larger surface features (Webster 2003). Since most of the surface features found in and on natural tissues are on the nanometer scale (Fig. 1), it has been widely speculated that adding nano-topographies to the surfaces of conventional biomaterials may promote the functions of various cell types. In this light, many nanostructured materials have been called bio-inspired nanomaterials (World Scientific 2007; Sato and Webster 2004). For example, nano- structured titanium implant surfaces promote bone cell responses leading to accelerated calcium deposition improving integration with surrounding bone compared to conventional titanium surfaces (Ergun et al. 2008; Webster et al. 2000, 1999; Yao et al. 2008). But bone is not the only application of nanomaterials in regenerative medicine. For cartilage applications, nano-structured poly- lactic-co-glycolic acid (PLGA) surfaces have been shown to accelerate chondrocyte adhesion and proliferation, as well as extracellular matrix production (Kay et al. 2002; Park et al. 2005; Savaiano and Webster 2004). Furthermore, vascular graft (PLGA) and stent (titanium) surfaces with nanometer surface roughness values improve endothelial (inner vessel cells) cell functions as compared to nano- smooth polymer and titanium surfaces (Lu et al. 2008; Choudhary et al. 2007; Miller et al. 2007; McCann-Brown et al. 2007; Miller et al. 2005). In addition to the incorporation of nanometer surface features on conventional biomaterials, intrinsic nano-sized materials such as carbon nanotubes (hydrophobic) (Khang et al. 2006, 2007; Webster et al. 2004; Elias et al. 2002) and helical rosette nanotubes (hydrophilic) (Chun et al. 2005, Biomed Microdevices DOI 10.1007/s10544-008-9264-6 DO09264; No of Pages D. Khang : J. Carpenter : Y. W. Chun : R. Pareta Division of Engineering, Brown University, Providence, RI 02912, USA T. J. Webster (*) Division of Engineering and Department of Orthopaedics, Brown University, 184 Hope Street, Providence, RI 02912, USA e-mail: Thomas_Webster@Brown.edu