Nanotechnology versus stem cell engineering: in vitro comparison of neurite inductive potentials

International Journal of Nanomedicine Dovepress open access to scientific and medical research O r i g in a l R e s e a r c h International Journal of Nanomedicine downloaded from https://www.dovepress.com/ by 54.37.163.172 on 12-Jul-2018 For personal use only. Open Access Full Text Article Nanotechnology versus stem cell engineering: in vitro comparison of neurite inductive potentials This article was published in the following Dove Press journal: International Journal of Nanomedicine 14 November 2014 Number of times this article has been viewed Michela Morano 1,* Sandra Wrobel 2,3,* Federica Fregnan 1 Ofra Ziv-Polat 4 Abraham Shahar 4 Andreas Ratzka 2 Claudia Grothe 2,3 Stefano Geuna 1 Kirsten Haastert-Talini 2,3 Department of Clinical and Biological Sciences, Università Degli Studi di Torino, Orbassano, Piemonte, Italy; 2 Institute of Neuroanatomy, Hannover Medical School, Hannover, LowerSaxony, Germany; 3Center for Systems Neuroscience (ZSN), Hannover, Lower-Saxony, Germany; 4NVR Research Ltd, Ness-Ziona, Israel 1 *These authors contributed equally to this work and share first authorship Purpose: Innovative nerve conduits for peripheral nerve reconstruction are needed in order to specifically support peripheral nerve regeneration (PNR) whenever nerve autotransplantation is not an option. Specific support of PNR could be achieved by neurotrophic factor delivery within the nerve conduits via nanotechnology or stem cell engineering and transplantation. Methods: Here, we comparatively investigated the bioactivity of selected neurotrophic factors conjugated to iron oxide nanoparticles (np-NTFs) and of bone marrow-derived stem cells genetically engineered to overexpress those neurotrophic factors (NTF-BMSCs). The neurite outgrowth inductive activity was monitored in culture systems of adult and neonatal rat sensory dorsal root ganglion neurons as well as in the cell line from rat pheochromocytoma (PC-12) cell sympathetic culture model system. Results: We demonstrate that np-NTFs reliably support numeric neurite outgrowth in all utilized culture models. In some aspects, especially with regard to their long-term bioactivity, np-NTFs are even superior to free NTFs. Engineered NTF-BMSCs proved to be less effective in induction of sensory neurite outgrowth but demonstrated an increased bioactivity in the PC-12 cell culture system. In contrast, primary nontransfected BMSCs were as effective as np-NTFs in sensory neurite induction and demonstrated an impairment of neuronal differentiation in the PC-12 cell system. Conclusion: Our results evidence that nanotechnology as used in our setup is superior over stem cell engineering when it comes to in vitro models for PNR. Furthermore, np-NTFs can easily be suspended in regenerative hydrogel matrix and could be delivered that way to nerve conduits for future in vivo studies and medical application. Keywords: iron oxide nanoparticles, conjugated neurotrophic factors, bone marrow-derived mesenchymal stem cells, genetic cell engineering, neurite outgrowth Introduction Correspondence: Kirsten Haastert-Talini Institute of Neuroanatomy, Hannover Medical School, Carl-Neuberg-Str 1, D-30625 Hannover, Germany Tel +49 511 532 2891 Fax +49 511 532 2880 Email haastert-talini.kirsten@ mh-hannover.de 5289 submit your manuscript | www.dovepress.com International Journal of Nanomedicine 2014:9 5289–5306 Dovepress © 2014 Morano et al. This work is published by Dove Medical Press Limited, and licensed under Creative Commons Attribution – Non Commercial (unported, v3.0) License. The full terms of the License are available at http://creativecommons.org/licenses/by-nc/3.0/. Non-commercial uses of the work are permitted without any further permission from Dove Medical Press Limited, provided the work is properly attributed. Permissions beyond the scope of the License are administered by Dove Medical Press Limited. Information on how to request permission may be found at: http://www.dovepress.com/permissions.php http://dx.doi.org/10.2147/IJN.S71951 Powered by TCPDF (www.tcpdf.org) Tissue engineering of peripheral nerves is an active field in research and development. Tissue-engineered nerves could become a valuable alternative to autologous nerve grafts, which are used as the gold standard for peripheral nerve reconstruction surgeries.1 This type of surgery is indicated whenever complete transection injuries of a peripheral nerve cannot be repaired by tension-free end-to-end coaptation of the severed nerve ends.2 Tissue engineering of peripheral nerves in order to bridge nerve defects and provide an optimized regenerative milieu is a complex effort that can only be achieved in a multidisciplinary setting.3 One important task is the delivery of regeneration-promoting molecules such as neurotrophic factors (NTFs) into the nerve defect or, more specifically, their application together with the artificial nerve graft. The main drawback in NTF application is the short half-life time, causing minimal efficacy of single NTF application at the time of reconstructive surgery or systemic application. Different ways to ensure extended availability of added NTFs at the site Dovepress International Journal of Nanomedicine downloaded from https://www.dovepress.com/ by 54.37.163.172 on 12-Jul-2018 For personal use only. Morano et al of nerve reconstruction have been attempted in recent years, including gene therapy via transplanted Schwann cells4 or nanotechnology approaches.5 Ex vivo gene therapy can be used to genetically induce the overexpression of selected NTFs in cells that are later transplanted as part of tissue-engineered nerve grafts.6 The usefulness of this approach has been proven already for transplanted Schwann cells overexpressing different isoforms of fibroblast growth factor-2 (FGF-2) in the rat sciatic nerve model.7,8 Schwann cells are crucially involved in successful peripheral nerve regeneration (PNR), but they are not easy to harvest and propagate for cell transplantation strategies. Therefore, mesenchymal stem cells (MSCs) have been addressed as an easy to access and potentially unlimited cell source for tissue-engineered nerve grafts.9 In this study, we performed stem cell engineering by nonviral genetic modification of bone marrow-derived mesenchymal stem cells (BMSCs), resulting in overexpression of selected NTFs. Another option to ensure availability of NTFs within an artifical nerve graft is the conjugation of the proteins to nanoparticles and their delivery within a hydrogel matrix for axonal regeneration. This strategy was also evaluated in the current work as an alternative strategy to cell-based delivery of NTFs. Three well-defined NTFs have been analyzed in the presented study. Nerve growth factor (NGF) is known as the neurotrophin with the strongest effect on sensory neurite outgrowth with regard to both axonal elongation and sprouting.10 The second neurotrophin analyzed was gliaderived neurotrophic factor (GDNF), wh (...truncated)