In vitro and in vivo evaluations of a novel post-electrospinning treatment to improve the fibrous structure of chitosan membranes for guided bone regeneration

Abstract

Electrospun chitosan membranes have been investigated for guided bone regeneration but are susceptible to swelling, dissolution, and loss of biomimetic nanofiber structure due to residual acid salts. A novel process was investigated for acidic salt removal from chitosan electrospun in 70% trifluoroacetic acid (TFA) by treating with triethylamine (TEA)/acetone and di-tert-butyl dicarbonate (tBOC) instead of the common NaCO treatment. TFA salt removal and nanofiber structure stabilization were confirmed by EDS, FTIR, F NMR and electron microscopy before and after soaking in water. Membrane degradation after 4 weeks in PBS with 100 µg ml lysozyme and osteoblastic proliferation were similar between TEA/tBOC-treated and NaCO-treated membranes. A simulated surgical tear test using surgical tacks showed that the peak tensile tear strength of the TEA/tBOC-treated chitosan membranes (62.1 ± 1.9 N mm) was significantly greater than a commercial polylactic acid (PLA) membrane (13.4 ± 0.4 N mm), similar to one commercial collagen membrane (55.3 ± 7.5 N mm) but lower than another commercial collagen membrane (133.9 ± 21.5 N mm). Rat 8 mm critical-sized calvarial defects covered with TEA/tBOC-treated chitosan membranes prevented soft tissue infiltration and supported new bone growth (15.76 ± 10.28%) similar to a commercial collagen membrane (16.08 ± 10.69%) at 12 weeks based on microCT analyses. Hence our novel TEA/tBOC process significantly improved nanofiber structure and mechanical strengths of electrospun chitosan membranes as compared to NaCO treated membranes, without affecting in vitro degradation or cytocompatibility, improved membrane mechanical properties to be greater than a commercial PLA membrane and to be in range of commercial collagen membranes and supported calvarial bone defect healing similar to collagen. Thus TEA/tBOC-treated chitosan membranes exhibit many characteristics and properties that strongly support their potential for use in guided bone regeneration.

Evaluation of Bone Regeneration of Simvastatin Loaded Chitosan Nanofiber Membranes in Rodent Calvarial Defects

“…In addition, similar results of membrane stability and degradation pattern during bone formation over a period of 8 -12 weeks were observed by Shin et al and Su et al where chitosan nanofiber membranes retained its shape and continuity as well as the required space for regeneration[12] [15].In the current study, histologic and micro-CT evaluations confirmed bone formation in calvarial defects as early as 4 weeks. Initially, bony islands were seen below the membranes and thicker osseous tissue was detected at the edges of the defect.…”

Simvastatin loaded chitosan guided bone regeneration membranes stimulate bone healing

“…ESCMs were electrospun using an in‐house box at room temperature and 40–60% humidity 2,19,20 . Chitosan (5.5% w/v) was dissolved in TFA‐DCM (70–30), loaded into 10 ml syringe with 20‐gauge blunt needle, and electrospun at 27 kV onto aluminum foil covered collector plate, rotating at ~8.4 rpm.…”

Tissue Engineering: Challenges and Selected Application

“…Combination of natural and synthetic polymers shows some advantages in bone tissue engineering. Some studies indicate positive effect of PCL/chitosan, 44 PCL/collagen, 45 PLA/hydroxyapatite, 46 TEA/tBOC-treated chitosan 47 for bone regeneration. Natural and synthetic polymers has been used to improve some existing solution for bone engineering e.g.…”