Three-dimensional engineered bone from bone marrow stromal cells and their autogenous extracellular matrix

Area of Science:

• Biomaterials Science
• Regenerative Medicine
• Tissue Engineering

Background:

• Traditional bone tissue engineering relies heavily on porous 3D scaffolds for cell seeding.
• Developing functional bone tissue requires cells, extracellular matrix (ECM), and appropriate structural support.

Purpose of the Study:

• To engineer 3D bone-like tissues without using any exogenous scaffolding.
• To investigate the potential of scaffold-less engineered bone constructs (EBCs) for bone regeneration.

Main Methods:

• Bone marrow stromal cells (BMSCs) were cultured in osteogenic medium on a 2D substrate.
• Confluent BMSCs produced autogenous ECM and contracted into scaffold-less cylindrical EBCs.
• EBCs were characterized via histology, biochemical assays, and mechanical testing, with some implanted in rats.

Main Results:

• Scaffold-less EBCs showed mineralization, alkaline phosphatase activity, and type I collagen, forming a periosteum-like layer.
• Mechanical testing revealed increasing tangent modulus from 7.5 MPa at 7 days to 29 MPa at 6 weeks.
• Implanted EBCs promoted bone development and vascularization, with explants containing osteoblasts, osteocytes, and osteoclasts after 4 weeks.

Conclusions:

• Successfully engineered the first 3D bone tissues without exogenous scaffolding.
• Scaffold-less EBCs possess intrinsic properties and in vivo potential for bone regeneration.
• This approach offers a novel strategy for creating bone-like tissues for regenerative medicine applications.