title: Reinforcement of poly-l-lactic acid electrospun membranes with strontium borosilicate bioactive glasses for bone tissue engineering.
abstract: Herein, for the first time, we combined poly-l-lactic acid (PLLA) with a strontium borosilicate bioactive glass (BBG-Sr) using electrospinning to fabricate a composite bioactive PLLA membrane loaded with 10% (w/w) of BBG-Sr glass particles (PLLA-BBG-Sr). The composites were characterised by scanning electron microscopy (SEM) and microcomputer tomography (μ-CT), and the results showed that we successfully fabricated smooth and uniform fibres (1-3μm in width) with a homogeneous distribution of BBG-Sr microparticles (<45μm). Degradation studies (in phosphate buffered saline) demonstrated that the incorporation of BBG-Sr glass particles into the PLLA membranes increased their degradability and water uptake with a continuous release of cations. The addition of BBG-Sr glass particles enhanced the membrane's mechanical properties (69% higher Young modulus and 36% higher tensile strength). Furthermore, cellular in vitro evaluation using bone marrow-derived mesenchymal stem cells (BM-MSCs) demonstrated that PLLA-BBG-Sr membranes promoted the osteogenic differentiation of the cells as demonstrated by increased alkaline phosphatase activity and up-regulated osteogenic gene expression (Alpl, Sp7 and Bglap) in relation to PLLA alone. These results strongly suggest that the composite PLLA membranes reinforced with the BBG-Sr glass particles have potential as an effective biomaterial capable of promoting bone regeneration.
  
  
  
  PLLA membranes were reinforced with 10% (w/w) of strontium-bioactive borosilicate glass microparticles, and their capacity to induce the osteogenic differentiation of bone marrow mesenchymal stem cells (BM-MSCs) was evaluated. These membranes presented an increased: degradability, water uptake, Young modulus and tensile strength. We also demonstrated that these membranes are non-cytotoxic and promote the attachment of BM-MSCs. The addition of the glass microparticles into the PLLA membranes promoted the increase of ALP activity (under osteogenic conditions), as well as the BM-MSCs osteogenic differentiation as shown by the upregulation of Alpl, Sp7 and Bglap gene expression. Overall, we demonstrated that the reinforcement of PLLA with glass microparticles results in a biomaterial with the appropriate properties for the regeneration of bone tissue.
authors.affiliation: 3B's Research Group - Biomaterials, Biodegradables and Biomimetics, University of Minho, Headquarters of the European Institute of Excellence on Tissue Engineering and Regenerative Medicine, AvePark, 4806-909 Taipas, Guimarães, Portugal; ICVS/3B's - PT Government Associate Laboratory, Braga/Guimarães, Portugal.
authors.forename: João S
authors.initials: JS
authors.lastname: Fernandes
authors.affiliation: Centre for Biomaterials and Tissue Engineering, School of Clinical Dentistry, University of Sheffield, Claremont Crescent, Sheffield S10 2TA, United Kingdom.
authors.forename: Piergiorgio
authors.initials: P
authors.lastname: Gentile
authors.affiliation: 3B's Research Group - Biomaterials, Biodegradables and Biomimetics, University of Minho, Headquarters of the European Institute of Excellence on Tissue Engineering and Regenerative Medicine, AvePark, 4806-909 Taipas, Guimarães, Portugal; ICVS/3B's - PT Government Associate Laboratory, Braga/Guimarães, Portugal.
authors.forename: Margarida
authors.initials: M
authors.lastname: Martins
authors.affiliation: 3B's Research Group - Biomaterials, Biodegradables and Biomimetics, University of Minho, Headquarters of the European Institute of Excellence on Tissue Engineering and Regenerative Medicine, AvePark, 4806-909 Taipas, Guimarães, Portugal; ICVS/3B's - PT Government Associate Laboratory, Braga/Guimarães, Portugal.
authors.forename: Nuno M
authors.initials: NM
authors.lastname: Neves
authors.affiliation: Centre for Biomaterials and Tissue Engineering, School of Clinical Dentistry, University of Sheffield, Claremont Crescent, Sheffield S10 2TA, United Kingdom.
authors.forename: Cheryl
authors.initials: C
authors.lastname: Miller
authors.affiliation: Centre for Biomaterials and Tissue Engineering, School of Clinical Dentistry, University of Sheffield, Claremont Crescent, Sheffield S10 2TA, United Kingdom.
authors.forename: Aileen
authors.initials: A
authors.lastname: Crawford
authors.affiliation: 3B's Research Group - Biomaterials, Biodegradables and Biomimetics, University of Minho, Headquarters of the European Institute of Excellence on Tissue Engineering and Regenerative Medicine, AvePark, 4806-909 Taipas, Guimarães, Portugal; ICVS/3B's - PT Government Associate Laboratory, Braga/Guimarães, Portugal. Electronic address: rpires@dep.uminho.pt.
authors.forename: Ricardo A
authors.initials: RA
authors.lastname: Pires
authors.affiliation: Centre for Biomaterials and Tissue Engineering, School of Clinical Dentistry, University of Sheffield, Claremont Crescent, Sheffield S10 2TA, United Kingdom. Electronic address: paul.hatton@sheffield.ac.uk.
authors.forename: Paul
authors.initials: P
authors.lastname: Hatton
authors.affiliation: 3B's Research Group - Biomaterials, Biodegradables and Biomimetics, University of Minho, Headquarters of the European Institute of Excellence on Tissue Engineering and Regenerative Medicine, AvePark, 4806-909 Taipas, Guimarães, Portugal; ICVS/3B's - PT Government Associate Laboratory, Braga/Guimarães, Portugal.
authors.forename: Rui L
authors.initials: RL
authors.lastname: Reis
mesh_terms: D000818:Animals; D001672:Biocompatible Materials / Q000494:pharmacology*; D015415:Biomarkers / Q000378:metabolism; D001842:Bone and Bones / Q000000981:diagnostic imaging / Q000187:drug effects / Q000502:physiology*; D002454:Cell Differentiation / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D048430:Cell Shape / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D020869:Gene Expression Profiling; D005898:Glass / Q000737:chemistry*; D008297:Male; D008567:Membranes, Artificial; D059630:Mesenchymal Stem Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D010012:Osteogenesis / Q000187:drug effects; D011091:Polyesters / Q000494:pharmacology*; D017208:Rats, Wistar; D013314:Stress, Mechanical; D013324:Strontium / Q000494:pharmacology*; D023822:Tissue Engineering / Q000379:methods*; D055114:X-Ray Microtomography
chemical_list: D001672:Biocompatible Materials; D015415:Biomarkers; D008567:Membranes, Artificial; D011091:Polyesters; C033616:poly(lactide); D013324:Strontium
keywords: BM-MSCs; Mineralisation; Osteogenic differentiation; PLLA membranes; Strontium borosilicate glasses