From implantation to degradation - are poly (l-lactide)/multiwall carbon nanotube composite materials really cytocompatible?

Poly (l-lactide)'s (PLLA) biodegradable properties are of special value in orthopaedic applications, but its mechanical strength limits its usage. To overcome this PLLA can be reinforced by multiwall carbon nanotubes (MWCNT). In this study the PLLA and MWCNT were combined to prepare nanostructured composites (nanocomposite) at 0, 0.1, 0.5 and 1wt.% reinforcement. The in vitro biocompatibility of these PLLA/MWCNT nanocomposites was evaluated taking into account the various stages of implantation including nanocomposite degradation. PLLA/MWCNT nanocomposites were highly biocompatible with human bone marrow stromal cells (HBMC). The potential surface degradation product, MWCNT, did not induce toxic responses on HBMC. However, the combination of MWCNT with lactic acid, resembling release after bulk degradation, significantly inhibited HBMC proliferation and activity. This study demonstrates the importance of comprehensive evaluations of novel materials for medical applications in predicting possible adverse effects during nanocomposite degradation. FROM THE CLINICAL EDITOR: This study scrutinizes the cytocompatibility of poly-L-lactide reinforced by multiwall carbon nanotubes, and concludes that the combination of MWCNT with lactic acid significantly inhibited human bone marrow stromal cell proliferation and activity, highlighting the importance of comprehensive evaluations of novel materials.