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Biocompatability of carbon nanoparticles with tissues of the neuromuscular system

Final Report Summary - NMS-CNT (Biocompatability of carbon nanoparticles with tissues of the neuromuscular system)

The NMS-CNT consortium focuses on solving a universal health problem, namely, the repair of extensive peripheral nerve lesions. The overarching aim of the NMS-CNT project was to initially evaluate the biocompatibility of a variety of carbon nanotube (CNT) configurations with neural and skeletal muscle tissues. This will hopefully facilitate and inform the consortium’s medium to long-term goal of developing marketable novel CNT-based nerve repair implants. The NMS-CNT consortium consists of three partners, University of Brighton (BTON), Pharmidex and AGH – University of Science & Technology, Poland (henceforth, referred to as AGH). The project is multidisciplinary bringing together expertise in nanochemistry, muscle physiology and biomaterials (AGH); neuropharmacology & pharmaceutical product development (Pharmidex); and neurophysiology, nerve growth & survival and mechanisms of neurodegeneration (BTON).

The specific aims of the project were: to prepare high quality, purified, water soluble preparations of CNTs including SW-CNTs, MW-CNTs, ultra-long-single-wall CNTs (ULSW-CNTs) and chemically functionalized preparations of each; to determine the catalyst content of each preparation via atomic absorption spectrometry; to characterize each CNT preparation via FT-IR and FT Raman spectroscopy; to characterize the wettability and surface energy of each CNT configuration; to identify through in vitro biocompatibility studies the CNT configurations that were generally biocompatible with adult neural tissue; to identify through in vivo biocompatibility studies the CNT preparation(s) that were generally biocompatible with adult skeletal muscle tissue; to study the neuropharmacology profiles of the CNTs; to disseminate insights to relevant stakeholders in the scientific and pharmaceutical technology communities including relevant SMEs, chemists, biologists, neuroscientists, neurologists, surgeons, physicians, environmental health scientists, and occupational health scientists.

The synthesis of consortium pristine and chemically functionalized CNT samples was undertaken and completed at AGH. Subsequently, a comprehensive characterization of the CNTs including analysis of morphology, size, degree of purification, structure of CNTs and evaluation of degree of chemical functionalization, were completed successfully. The solubility of each CNT configuration in a multitude of relevant aqueous fluids was also tested. The MWCNT preparations were found to be most soluble in a variety of tissue culture medium, particularly when CNT solubility was tested for at least 24 hours. Consequently, the MWCNTs were used primarily to achieve the specific objectives of project NMS-CNT. A comprehensive catalogue of assays was used to assess the pharmacological cytotoxicity of the MWCNTs. Data from this analysis of the Adsorption, Distribution, Metabolism and Excretion (ADME) of the MWCNTs suggests that in vivo, MWCNTs are unlikely to trigger haemotoxic, hepatotoxic nor neurotoxic cellular responses.

The MWCNT configuration was also found to be the most biocompatible with adult neural and skeletal muscle tissue. Importantly, our data indicate that CNTs should not be administered in powder form as this resulted in significant disruption of the fascicular structure of skeletal muscle. Robust muscle regeneration occurred at implant sites following administration of the MWCNTs in solution. With regard to nerve regeneration, the MWCNT configuration was the most effective in supporting neurite outgrowths from neurons.

The fate of CNTs within cells is of importance has it can lead to profound changes in cell function. We have recently shown through a deliverable of this project (Fraczek-Szczypta et al., 2012. J Nanopart Res 14:1181) that macrophages from a macrophage cell line, readily take up MWCNT-Fs with a reduction in normal cell function. Projects such as NMS-CNT therefore highlight the importance to normal cell function of undertaking systematic and comprehensive cellular biocompatibility analysis of CNTs.

In conclusion, project NMS-CNT has delivered with added value. Key project insights into the biocompatibility of CNTs, particularly, the MWCNT configuration, will be of interest to a multitude of stakeholders. Our promising data suggests that with additional functionalization, MWCNTs could realistically help promote peripheral nerve repair. In the medium-term, further research is required to progress towards the consortium’s ultimate goal of producing marketable CNT-based nerve repair devices that will likely bring substantial socio-economic benefits to the European Community.