Bone-targeted bortezomib increases bone formation within Calvarial trans-sutural distraction osteogenesis

Area of Science:

• Orthopedic Surgery
• Regenerative Medicine
• Biomaterials

Background:

• Trans-sutural distraction osteogenesis (TSDO) for craniofacial disharmony often fails due to poor bone bridge formation.
• Bisphosphonates (BP) target bone and can deliver therapeutics to the bone microenvironment.
• Bone-targeted Bortezomib (BP-Btz) conjugate aims to improve TSDO by promoting osteogenesis and inhibiting osteoclastogenesis.

Purpose of the Study:

• To evaluate the efficacy of bone-targeted Bortezomib (BP-Btz) in promoting trans-sutural distraction osteogenesis (TSDO).
• To assess the pharmacological properties and biological effects of BP-Btz in a TSDO model.

Main Methods:

• In vitro studies using suture-derived mesenchymal stem cells (SuSCs) and osteoclasts treated with Bortezomib (Btz) and BP-Btz.
• Local injection of BP-Btz into sagittal sutures in a TSDO model.
• Assessment of bone formation and resorption markers, including osteoid area and osteoclast surface.
• Pharmacological evaluation using fluorescent BP analogs and ubiquitinated protein levels.

Main Results:

• BP-Btz stimulated osteogenic differentiation of SuSCs and inhibited osteoclastogenesis in vitro.
• In vivo, BP-Btz treatment led to increased osteoid area and enhanced osteogenesis.
• BP-Btz demonstrated reduced osteoclast surface and improved bone metabolism in the suture expansion model.
• Pharmacological studies confirmed BP-Btz's bone targeting, sustained release, and higher local concentration compared to free Btz.

Conclusions:

• Bone-targeted Bortezomib (BP-Btz) conjugate is a promising therapeutic strategy for enhancing TSDO.
• BP-Btz effectively promotes bone formation and inhibits bone resorption at the surgical site.
• The targeted delivery and sustained release of BP-Btz improve its efficacy in TSDO treatment.