Hard Tissue Augmentation of Aged Bone by Means of a Tin-Free PLLA-PCL Co-Polymer Exhibiting in vivo Anergy and Long-Term Structural Stability

Gerontology. 2019;65(2):174-185. doi: 10.1159/000494798. Epub 2019 Jan 24.


Background: Due to aging, tissue regeneration gradually declines. Contemporary strategies to promote tissue-specific regeneration, in particular in elderly patients, often include synthetic material apt for implantation primarily aiming at upholding body functions and regaining appropriate anatomical and functional integrity.

Objective: Biomaterials suitable for complex reconstruction surgical procedures have to exert high physicochemical stability and biocompatibility.

Method: A polymer made of poly-L-lactic acid and poly-ε-caprolactone was synthesized by means of a novel tin-free catalytic process. The material was tested in a bioreactor-assisted perfusion culture and implanted in a sheep model for lateral augmentation of the mandible. Histological and volumetric evaluation was performed 3 and 6 months post-implantation.

Results: After synthesis the material could be further refined by cryogrinding and sintering, thus yielding differently porous scaffolds that exhibited a firm and stable appearance. In perfusion culture, no disintegration was observed for extended periods of up to 7 weeks, while mesenchymal stromal cells readily attached to the material, steadily proliferated, and deposited extracellular calcium. The material was tested in vivo together with autologous bone marrow-derived stromal cells. Up to 6 months post-implantation, the material hardly changed in shape with composition also refraining from foreign body reactions.

Conclusion: Given the long-term shape stability in vivo, featuring imperceptible degradation and little scarring as well as exerting good compatibility to cells and surrounding tissues, this novel biomaterial is suitable as a space filler in large anatomical defects.

Keywords: 3D culture; Hard tissue; Mesenchymal stem cells; Regeneration.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Biocompatible Materials / pharmacology
  • Bone Regeneration / physiology
  • Bone and Bones* / pathology
  • Bone and Bones* / surgery
  • Cellular Senescence
  • Humans
  • Materials Testing / methods*
  • Mesenchymal Stem Cells / physiology*
  • Osteogenesis*
  • Polyesters / pharmacology*
  • Porosity
  • Sheep
  • Tissue Engineering* / instrumentation
  • Tissue Engineering* / methods
  • Tissue Scaffolds*


  • Biocompatible Materials
  • Polyesters
  • polycaprolactone
  • poly(lactide)