Recombinant Human Parathyroid Hormone Biocomposite Promotes Bone-to-Tendon Interface Healing by Enhancing...

Area of Science:

• Biomaterials science
• Orthopedic surgery
• Regenerative medicine

Background:

• Chronic rotator cuff tears (RCTs) present a significant challenge in orthopedic surgery.
• Effective healing of the bone-to-tendon interface (BTI) is crucial for successful RCT repair.
• Current treatments often yield suboptimal functional recovery, necessitating innovative therapeutic strategies.

Purpose of the Study:

• To evaluate the efficacy of a novel recombinant human parathyroid hormone (rhPTH) biocomposite in promoting BTI healing.
• To assess the impact of the rhPTH biocomposite on genetic, histologic, biomechanical, and micro-CT parameters in a rabbit chronic RCT model.

Main Methods:

• Sixty-four rabbits with chronic RCTs were divided into four groups: saline, nanofiber sheet alone, rhPTH-soaked nanofiber sheet, and rhPTH biocomposite.
• rhPTH release kinetics were analyzed in vitro.
• Nanofiber scaffolds were implanted post-surgery, with evaluations at 4 and 12 weeks.
• Analyses included gene expression (COL1A1, COL3A1, BMP-2), histology, biomechanics, micro-CT, and serology.

Main Results:

• The rhPTH biocomposite group demonstrated significantly higher mRNA expression of COL1A1, COL3A1, and BMP-2 at 4 weeks post-surgery.
• At 12 weeks, the rhPTH biocomposite group exhibited superior collagen fiber continuity, orientation, density, mature fibrocartilage, and bone-to-tendon junction formation.
• Biomechanical testing revealed the highest load-to-failure rate in the rhPTH biocomposite group (48.2 ± 4.5 N/kg).
• Micro-CT analysis confirmed enhanced bone and tissue mineral density and bone volume in the rhPTH biocomposite group.

Conclusions:

• rhPTH biocomposite effectively accelerates BTI healing in a chronic RCT rabbit model.
• The biocomposite enhances early gene expression and promotes tenogenesis, chondrogenesis, and osteogenesis by 12 weeks.
• This study suggests rhPTH biocomposites are a promising adaptable biomaterial for human RCT repair.