Scientists from CNRS, in collaboration with hospital-university practitioners, veterinarians, and academics, have developed innovative biomaterials that not only replicate the chemical composition of bone but also its three-dimensional microarchitecture.
These materials could significantly improve the quality of bone repair compared to autografts, as opposed to ceramics, which are necessarily macroporous, difficult to resorb, and result in the formation of bone with a low remodeling rate.
a) SEM micrograph of decalcified human compact bone at low magnification. Scale: 50 µm.
b) Same sample at high magnification. Scale: 5 µm.
c) SEM micrograph of a synthetic collagen-based material with a dense and organized biomimetic structure (Col100). Scale: 5 µm.
d) SEM micrograph of a non-organized collagen fibrillar network with large interfibrillar spaces (Col40). Scale: 2 µm.
The diagram under (b) illustrates the plywood-like organization. Bone tissue is composed of a hybrid organic/inorganic matrix primarily made up of fibrils of a protein called collagen and nanoparticles of apatite (HA), the most stable crystalline phase of calcium phosphate. It is this unique composition that gives bones their mechanical properties.
Bone is a remarkable tissue with an impressive capacity for self-repair. However, in cases of significant defects, this innate regenerative capacity is often insufficient. Traditional approaches to bone repair rely on the use of autologous bone grafts, meaning the donor and recipient are the same person. These grafts are highly effective due to their biological properties, which ensure graft acceptance, good bone growth, and an established vascular network.
However, these autologous bone grafts have certain limitations, such as morbidity related to the donor site and the availability of a sufficient amount of bone for harvesting. This is why research has focused on developing alternative bone substitutes capable of effectively supporting tissue regeneration.
Ceramics, and particularly bioceramics, mineral-based materials, are widely used in clinical practice for bone tissue repair. While they offer optimal mechanical properties (rigidity), their resorption in the body remains improvable, especially because the properties conferred by the organic matrix are absent (video).
In this context, scientists from the Laboratoire de chimie de la matière condensée de Paris (CNRS/Sorbonne Université), in collaboration with hospital-university practitioners (Université Paris Cité, Université Paris Nord, Hôpital Bichat, INSERM), veterinarians (IMM), and academics (ENS Lyon), have developed materials designed by biomimetic self-assembly that governs the precise arrangement of collagen and apatite. They achieved a structure closer to that of natural bone than any existing biomaterials on the market.
A battery of analytical techniques, including histopathology, computer-assisted tomography, wide-angle X-ray scattering, microindentation, and electron microscopy, was used to evaluate the biological, mechanical, and structural performance of these new materials. The results demonstrate their ability to significantly improve the quality of bone repair compared to ceramics.
These biomimetic materials not only promote cellular colonization but also allow natural resorption and remodeling processes to develop, leading to faster and more complete healing. Moreover, these results demonstrate for the first time that the structural patterns of the bone matrix can be involved in its performance as a graft.
This work, published in
Nature, opens new avenues for the development of competitive biomaterials for bone repair and regeneration, as well as for the establishment of relevant models to improve our fundamental understanding of bone biomineralization.
Editor: CCdM
Reference
Marc Robin, Elodie Mouloungui, Gabriel Castillo Dali, Yan Wang, Jean-Louis Saffar, Graciela Pavon-Djavid, Thibaut Divoux, Sébastien Manneville, Luc Behr, Delphine Cardi, Laurence Choudat, Marie-Madeleine Giraud-Guille, Anne Meddahi-Pellé, Fannie Baudimont, Marie-Laure Colombier & Nadine Nassif.
Mineralized collagen plywood contributes to bone autograft performance
Nature 2024
https://doi.org/10.1038/s41586-024-08208-z