Gene-programmed micro-nano metabolic engine drives coupled osteogenic-angiogenic regeneration.

Area of Science:

• Biomaterials Science
• Regenerative Medicine
• Cell Biology

Background:

• Effective bone healing relies on coupled osteogenic-angiogenic regeneration, dependent on metabolic communication between mesenchymal stem cells and endothelial cells.
• Nitric oxide (NO) produced by endothelial nitric oxide synthase (eNOS) is crucial for this process, but its synthesis is impaired in hypoxic bone defects.
• Hypoxia restricts eNOS expression and depletes its substrate, l-arginine, hindering NO biosynthesis and subsequent tissue regeneration.

Purpose of the Study:

• To develop a gene-programmed micro-nano metabolic engine (GP-MNME) for reconstructing NO metabolic homeostasis in bone defects.
• To enhance the synergistic coupling of osteogenic and angiogenic signaling pathways for improved bone regeneration.
• To address the limitations of hypoxic microenvironments in large bone defects by proactively modulating cellular metabolism.

Main Methods:

• Fabrication of a dual-module GP-MNME: a nano-module with l-arginine-modified nanoparticles for BMP-2 mRNA delivery and a micro-module of GelMA microgels for BMSC targeting and nano-module encapsulation.
• In situ delivery of GP-MNME to bone defects to enrich BMSCs and release nano-modules.
• Evaluation of GP-MNME's effect on eNOS expression, l-arginine supply, NO production, osteogenic mineralization, and angiogenic sprouting.

Main Results:

• GP-MNME successfully upregulated eNOS expression and supplied l-arginine, leading to a synergistic increase in NO production (>3.1-fold).
• Re-established NO homeostasis promoted osteogenic mineralization and angiogenic sprouting (both >3-fold).
• Significant promotion of coupled osteogenic-angiogenic regeneration in rat bone defects, evidenced by increased new bone formation (>2.4-fold).

Conclusions:

• The developed GP-MNME effectively reconstructs intracellular NO biosynthesis in situ, presenting a proactive metabolic modulation strategy for bone regeneration.
• This approach overcomes the challenges posed by hypoxic microenvironments in large bone defects.
• The study demonstrates the potential of engineered metabolic engines for enhancing coupled osteogenic-angiogenic regeneration.