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Tampere, Finland

Frantzen J.,University of Turku | Palli A.,University of Tampere | Kotilainen E.,University of Turku | Heino H.,Bioretec Ltd | And 13 more authors.
International Journal of Biomaterials | Year: 2011

A poly-70L/30DL-lactide (PLA70)-β-tricalcium phosphate (β-TCP) composite implant reinforced by continuous PLA-96L/4D-lactide (PLA96) fibers was designed for in vivo spinal fusion. The pilot study was performed with four sheep, using titanium cage implants as controls. The composite implants failed to direct bone growth as desired, whereas the bone contact and the proper integration were evident with controls 6 months after implantation. Therefore, the PLA70/β-TCP composite matrix material was further analyzed in the in vitro experiment by human and ovine adipose stem cells (hASCs and oASCs). The composites proved to be biocompatible as confirmed by live/dead assay. The proliferation rate of oASCs was higher than that of hASCs at all times during the 28d culture period. Furthermore, the composites had only a minor osteogenic effect on oASCs, whereas the hASC osteogenesis on PLA70/β-TCP composites was evident. In conclusion, the composite implant material can be applied with hASCs for tissue engineering but not be evaluated in vivo with sheep. Copyright © 2011 Janek Frantzén et al.

Ahola N.,Tampere University of Technology | Veiranto M.,Tampere University of Technology | Veiranto M.,Bioretec Ltd | Rich J.,Aalto University | And 4 more authors.
Journal of Biomaterials Applications | Year: 2013

There is an increasing need for synthetic bone substitute materials that decrease the need for allografts and autografts. In this study, composites of β-tricalcium phosphate and a biodegradable poly(L-lactide-co- Éε-caprolactone) were manufactured using extrusion to form biodegradable composites with high β-tricalcium phosphate contents for osteoconductivity. The hydrolytic degradation of the composites containing 0, 10, 20, 35 and 50% of β-tricalcium phosphate was studied in vitro for 52 weeks. During the study, it was observed that β-tricalcium phosphate did not have an effect on the degradation rate of the polymer matrix. However, the crystallinity of the materials increased throughout the test series and changes in glass transition temperatures were also observed as the comonomer ratio of the polymer matrix changed as the degradation proceeded. The results show that the materials have desirable degradation properties and, thus, possess great potential as bioabsorbable and osteoconductive bone filling materials. © 2012 The Author(s).

Paakinaho K.,Tampere University of Technology | Heino H.,Tampere University of Technology | Heino H.,Bioretec Ltd | Vaisanen J.,Tampere University of Technology | And 2 more authors.
Journal of the Mechanical Behavior of Biomedical Materials | Year: 2011

The hydrolytic degradation of oriented poly(L-lactide-co-glycolide) 85L/15G (PLGA 85/15) sample materials with various amounts of lactide monomer was monitored in vitro at 37 °C. The materials were manufactured from medical grade PLGA 85/15 by a two-step melt extrusion-die drawing process. Results showed that the hydrolytic degradation rate depended highly on the lactide monomer content, which in turn influenced the retention of mechanical properties, mass loss, crystallinity, and dimensional stability. Even small quantities of lactide monomer (0.05-0.20 wt%) affected especially the retention of mechanical properties, which started to decline rapidly upon the inherent viscosity reaching 0.6-0.8 dl/g due to hydrolytic degradation. Based on our hydrolytic degradation data, we constructed a simplified mathematical model of degradation-related strength retention and recommend it as a functional quality control tool for melt-processed biodegradable medical devices manufactured from poly(L-lactide-co-glycolide) 85L/15G. © 2011 Elsevier Ltd.

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