PTHrP Overexpression in Periosteum Promotes Alveolar Bone Formation.

Area of Science:

• Regenerative Medicine
• Oral Biology
• Gene Therapy

Background:

• Alveolar bone dehiscence, common in thin bone regions, can lead to gingival recession.
• In situ alveolar bone thickening using local bioagents is a promising therapeutic strategy.
• Parathyroid hormone-related protein (PTHrP) is crucial for skeletal development and bone remodeling.

Purpose of the Study:

• To investigate the efficacy of a recombinant adeno-associated virus (rAAV) vector overexpressing Pthlh (rAAV9-Pthlh) for in situ alveolar bone thickening.
• To evaluate the effects of local PTHrP overexpression on alveolar bone formation and related cellular mechanisms.
• To assess the protective potential of rAAV9-Pthlh against alveolar crest loss in a rat model.

Main Methods:

• Development of rAAV9-Pthlh vector for local administration.
• Split-mouth study design in rats with single submucosal injection of rAAV9-Pthlh.
• In vivo and ex vivo micro-computed tomography (micro-CT) for bone thickness assessment, RNA sequencing, immunofluorescence, and cell culture studies.

Main Results:

• Significant increase in alveolar bone thickness and periosteal thickening observed 6 weeks post-injection.
• Elevated expression of osteogenesis markers (OCN, COL1A1) and increased mitophagy activity in periosteal tissue.
• Overexpression of Pthlh promoted proliferation and migration of periosteal stem cells, with mitophagy involvement.

Conclusions:

• Local rAAV9-Pthlh injection effectively enhances in situ alveolar bone formation.
• This gene therapy approach holds potential for preventing dehiscence in aging individuals or post-orthodontic interventions.
• PTHrP plays a vital role in alveolar bone regeneration and chondroskeletal progenitor expansion.