New scaffolds for better healing and regeneration of bone tissue

Bone is a highly vascularized tissue, and the relationship between angiogenesis (blood vessel formation) and bone healing has long been discussed by the scientific community, with several studies describing impaired bone healing due to lack of or decreased angiogenesis. Traditional approaches, such as the use of grafts, often result in complications due to inadequate vascular supply to the implants, leading to poor integration and the formation of necrotic tissue.

To address this problem, researchers from the Institute of Bioengineering of Catalonia (IBEC) led by Óscar Castaño, principal investigator of the Biomaterials for Regenerative Therapies group, have developed a novel approach. They applied the 3D bioprinting technique to develop scaffolds with a glassy structure based on polylactic acid and calcium phosphate that promote angiogenesis and the maturation of blood vessels.

Bone is composed of both a non-mineralized organic part (mainly collagen) and a mineralized inorganic part (mainly hydroxyapatite). In this structure, 3D porosity is necessary to ensure the transport of nutrients and oxygen, as well as to allow vascularization, cellular infiltration and waste removal. The researchers’ approach was based on the use of glassy scaffolds based on calcium phosphate (CaP) to improve the properties of polylactic acid (PLA) and obtain a material that meets the chemical, mechanical and biological needs of the tissue. osseous.

The new PLA-CaP scaffolds allow adequate vascularization, which not only heals the tissue, but also allows efficient regeneration, which results in the reduction or elimination of bone damage.

To create these scaffolds, the researchers used 3D printing to achieve precise control over scaffold geometry, porosity, and surface characteristics. “This innovative method allows us to create customizable scaffolds that imitate the structure of natural bone, essential to enhance cellular infiltration and nutrient exchange during the healing process,” underlines Celia Ximenes-Carballo, first author of the study.

The new scaffolds promote healing and regeneration of bone tissue. (Image: IBEC)

In vitro tests revealed that the 3D-printed scaffolds promoted the proliferation of human mesenchymal stem cells and stimulated the secretion of vascular endothelial growth factor, a critical factor that promotes the formation of blood vessels. Additionally, the scaffolds maintained the release of calcium ions at physiological levels, another vital element in stimulating vascularization.

On the other hand, subcutaneous in vivo tests in a mouse model also showed promising results. Just one week after implantation, the scaffolds showed good integration and notable blood vessel infiltration. PLA-CaP scaffolds were particularly effective, showing increased vessel maturation after four weeks with no signs of vascular regression. Analysis of the blood vessels revealed that the walls were initially thin, but became thicker and more stable over time. This progression indicates that the scaffolds not only provide initial support for blood vessel growth, but also foster an environment conducive to long-lasting vascularization, essential for bone regeneration.

The development of these advanced scaffolds highlights the synergistic effects of combining 3D printing technology with bioactive materials such as calcium-releasing particles. The architecture of PLA-CaP scaffolds not only facilitates better vascularization but also supports osteogenesis, paving the way for more effective bone healing strategies with the potential to reduce graft failure rates.

The study is titled “Combining three-dimensionality and CaP glass-PLA composites: Towards an efficient vascularization in bone tissue healing.” And it has been published in the academic journal Biomaterials Advances. (Source: IBEC)