Interfacial Compatibilization into PLA/Mg Composites for Improved In Vitro Bioactivity and Stem Cell Adhesion.

Meriam Ben Abdeljawad,Chiara Argentati,Francesco Morena,Rosica Mincheva,Sabata Martino,Jérémy Odent,Xavier Carette,Jean-Marie Raquez,Maurice-François Gonon

doi:10.3390/molecules26195944

Meriam Ben Abdeljawad, Chiara Argentati + Show 7 more

Open Access

https://doi.org/10.3390/molecules26195944

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Abstract

The present work highlights the crucial role of the interfacial compatibilization on the design of polylactic acid (PLA)/Magnesium (Mg) composites for bone regeneration applications. In this regard, an amphiphilic poly(ethylene oxide-b-L,L-lactide) diblock copolymer with predefined composition was synthesised and used as a new interface to provide physical interactions between the metallic filler and the biopolymer matrix. This strategy allowed (i) overcoming the PLA/Mg interfacial adhesion weakness and (ii) modulating the composite hydrophilicity, bioactivity and biological behaviour. First, a full study of the influence of the copolymer incorporation on the morphological, wettability, thermal, thermo-mechanical and mechanical properties of PLA/Mg was investigated. Subsequently, the bioactivity was assessed during an in vitro degradation in simulated body fluid (SBF). Finally, biological studies with stem cells were carried out. The results showed an increase of the interfacial adhesion by the formation of a new interphase between the hydrophobic PLA matrix and the hydrophilic Mg filler. This interface stabilization was confirmed by a decrease in the damping factor (tanδ) following the copolymer addition. The latter also proves the beneficial effect of the composite hydrophilicity by selective surface localization of the hydrophilic PEO leading to a significant increase in the protein adsorption. Furthermore, hydroxyapatite was formed in bulk after 8 weeks of immersion in the SBF, suggesting that the bioactivity will be noticeably improved by the addition of the diblock copolymer. This ceramic could react as a natural bonding junction between the designed implant and the fractured bone during osteoregeneration. On the other hand, a slight decrease of the composite mechanical performances was noted.

Highlights

The choice of the bioresorbable material is one of the crucial factors for the design of novel bone implants
These findings demonstrated that polylactic acid (PLA), PLA/10 Mg, and PLA/10 Copo/10 Mg were suitable for mesenchymal stem cell cultures, while PLA/10 Copo film has a potential adverse effect on the viability of both stem cells
We observed an adverse effect of PLA/10 Copo on both stem cells that lost the canonical morphology, shrank, and became irregular or formed large aggregates attached to the film surface beginning at D3

Summary

Introduction

The choice of the bioresorbable material is one of the crucial factors for the design of novel bone implants The latter must fulfil additional requirements compared to permanent implants available on the market, e.g., to be metabolized by the human body without leaving any trace and gradually lose their mechanical strength during the healing process until bone regeneration [1]. More they must be designed to degrade at a rate that will slowly transfer load from the implant to the healing bone [2]. To counterbalance the aforementioned issues, many efforts have been addressed by loading the polymer matrix with hydroxyapatite filler [11,12], hydroxyapatite combined with graphene [13], calcium phosphate [14], bioactive glass ceramics [15] and bioactive fillers such as calcium silicates (CaSi) and dicalcium phosphate dihydrate (DCPD) [16] for bone tissue engineering, bone graft substitute and dentistry applications

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