Ectopic vascularized bone formation by human mesenchymal stem cell microtissues in a biocomposite scaffold

Area of Science:

• Biomaterials Science
• Regenerative Medicine
• Stem Cell Biology

Background:

• Human bone marrow mesenchymal stem cells (hBM-MSCs) exhibit osteogenic potential, immunomodulatory properties, and can mimic in vivo microenvironments.
• Three-dimensional multicellular hBM-MSC microtissues (MTs) are promising for bone tissue engineering.

Purpose of the Study:

• To evaluate the potential of hBM-MSC MTs combined with a biocomposite scaffold for forming vascularized bone-like tissue in an ectopic site.
• To compare the characteristics of a novel biocomposite scaffold (GCnHP) with a control scaffold (GCnH).

Main Methods:

• Fabrication of a biocomposite scaffold (gelatin, carboxymethyl cellulose, polyvinyl alcohol, nano-hydroxyapatite) using freeze-drying.
• Characterization of scaffold properties (porosity, mechanical strength, degradation).
• In vitro culture of hBM-MSC MTs on scaffolds, followed by in vivo implantation in immunocompromised mice for 4 weeks.

Main Results:

• The GCnHP scaffold exhibited enhanced mechanical strength, water adsorption, and degradation resistance compared to GCnH.
• hBM-MSC MTs on scaffolds supported cell proliferation, osteogenic differentiation, matrix mineralization, and gene expression (runX2, ALP, COL1, OC).
• In vivo studies revealed newly synthesized collagen, host vasculature infiltration, and expression of bone-related markers (OC, OSX), along with VEGF indicating angiogenesis.

Conclusions:

• The combination of hBM-MSC MTs and the GCnHP biocomposite material is effective for in vivo bone-like tissue formation.
• This approach demonstrates potential for non-load-bearing bone tissue repair and regenerative medicine applications.