image: At the top of the graph, biomimetic scaffolds from macro, micro to nano mimic the structural, mechanical, electrical, and chemical properties of natural bone. Natural bone consists of an ordered structure of piezoelectric collagen fibers and HA arranged with collagen fibers, the corresponding biomimetic scaffolds consist of ordered piezoelectric PLLA fibers and HA particles on the surface. At the bottom of the graph, Piezoelectric bionic scaffolds act on bone defects in four ways: stem cell recruitment, stem cell differentiation, anti-inflammatory, and angiogenesis, and lead to bone regeneration. Scaffold releases calcium ions to alter chemical environment, allowing recruitment of stem cells, which are differentiated towards osteogenesis by ultrasound piezoelectricity. The bone-like microenvironment promotes M2-type polarization of macrophages and increased angiogenesis. Scaffolds promote osteogenic differentiation by affecting calcium channels in MSCs and the PI3K signaling pathway.
Credit: ©Science China Press
This study is led by Dr. Zhou Li (Beijing Institute of Nanoenergy and Nanosystems, Chinese Academy of Sciences) and Chunying Chen (National Center for Nanoscience and Technology). Orderly hierarchical structure with balanced mechanical, chemical, and electrical properties is the basis of the natural bone microenvironment. Inspired by nature, we developed a piezocatalytically-induced controlled mineralization strategy using piezoelectric polymer poly-L-lactic acid (PLLA) fibers with ordered micro-nano structures to prepare biomimetic tissue engineering scaffolds with a bone-like microenvironment (pcm-PLLA), in which PLLA-mediated piezoelectric catalysis promoted the in-situ polymerization of dopamine and subsequently regulated the controllable growth of hydroxyapatite crystals on the fiber surface. PLLA fibers, as analogs of mineralized collagen fibers, were arranged in an oriented manner, and ultimately formed a bone-like interconnected pore structure; in addition, they also provided bone-like piezoelectric properties. The uniformly sized HA nanocrystals formed by controlled mineralization provided a bone-like mechanical strength and chemical environment.
The pcm-PLLA scaffold could rapidly recruit endogenous stem cells, and promote their osteogenic differentiation by activating cell membrane calcium channels and PI3K signaling pathways through ultrasound-responsive piezoelectric signals. In addition, the scaffold also provided a suitable microenvironment to promote macrophage M2 polarization and angiogenesis, thereby enhancing bone regeneration in skull defects of rats.
The proposed multifaceted bionic natural bone strategy provides a new idea for the development of bone tissue engineering scaffolds.
See the article:
Piezocatalytically-induced controllable mineralization scaffold with bone-like microenvironment to achieve endogenous bone regeneration
https://doi.org/10.1016/j.scib.2024.04.002
Journal
Science Bulletin