Bioengineering nanotechnology: towards the clinic.

The application of nanotechnology in the field of life sciences offers the potential to study biological systems with unprecedented resolution at the nanoscale, and to solve medical problems that affect millions of patients across the globe. Significant progress has been achieved over the past 2?3 decades leading to, for example, the approval of nanoformulations for delivering drugs to tumors and other diseased sites [1]. To date, nearly 30 nanotechnology-based products have been approved for clinical use, focused mainly on liposomal formulations and stealth polymer?drug conjugates. In addition to therapeutic nanoparticles for drug delivery, important topics include: (i) biomimetic nano- or micro-structured materials for tissue engineering and regenerative medical applications, (ii) nanobiosensors, particularly those lab-on-chip-based systems for disease diagnosis at the point of care, (iii) nano-probes for in vivo sensing/imaging, cell tracking and monitoring disease pathogenesis or therapy and (iv) nanotechnology-based tools that accelerate scientific discovery and elucidation of basic biology [2, 3]. Some of the exciting emerging topics involve the development of multifunctional nanoparticles that can fulfil two or more of the above-mentioned functions (e.g. theranostics that include diagnostics and therapy) [4] and the use of nano-sized materials to monitor and manipulate the fate of transplanted (stem) cells and the microenvironments where they reside in vivo [5, 6]. For example, we recently reported that nano-sized aptamer sensors that are engineered on the surface of stem cells could be delivered by cells to target niches in the body where they can potentially report the cellular functions and cell?cell communication in real-time [7]. Moreover, drug-carrying nano- or micro-particles can be conjugated with therapeutic cells prior to transplantation to enable the control of the fate and therapeutic function of cells in a sustained manner in vivo [8,?9]. This special issue highlights some of the most recent advances in the exciting field of bioengineering nanotechnology. The themes covered in this issue include nanoparticle systems for tracking transplanted stem cells using a variety of imaging modalities, synthesis of smart nanomaterials for drug delivery and targeting specific intracellular organalles, elucidating how physical cues provided by nano- or micro-fabricated scaffolds impact cell phenotype, novel nanocomposite materials for biosensing, biomimetic assembly of nanostructures for studying molecular interactions, and high content analysis for assessing nanotoxicity. We believe next-generation nanomaterials that are currently under development will transform our understanding of biological mechanisms, and revolutionize clinical practice through ushering in new diagnostics and therapeutic paradigms. As nanotechnology becomes increasingly accessible to research laboratories, significant advances leading to paradigm shifts in basic biology and medicine will require connecting the right technology to the right problem and ensuring that the most pertinent criteria are correctly identified and addressed. References [1] Peer D et al Nat. Nanotechnol. 2 751?60 [2] Wang A Z, Langer R S and Farokhzad O C 2011 Annu. Rev. Med. doi: 10.1146/annurev-med-040210-162544 [3] Farokhzad O C and Langer R 2006 Adv. Drug Deliv. Rev. 58 1456?9 [4] Zhao W and Karp J M 2009 Nat. Mater. 8 453?4 [5] Ferreira L, Karp J M, Nobre L and Langer R 2008 Cell Stem Cell 3 136?46 [6] Zhao W and Karp J M 2009 ChemBioChem 10 2308?10 [7] Zhao W et al 2011 Nat. Nanotechnol. 6 524?31 [8] Stephan M T, Moon J J, Um S H, Bershteyn A and Irvine D J 2010 Nat. Med. 16 1035?41 [9] Sarkar D, Ankrum J A, Teo G S, Carman C V and Karp J M 2011 Biomaterials 32 3053?61