Bone formation by BMP-7-transduced human gingival keratinocytes

Area of Science:

• Regenerative Medicine
• Cell Biology
• Biomaterials Science

Background:

• Bone morphogenetic proteins (BMPs) are crucial signaling molecules in bone and tooth development.
• Recombinant BMPs can stimulate bone and dentin regeneration in adult tissues.
• Fibroblasts genetically modified with BMP cDNA can form bone and differentiate into osteoblasts in vivo.

Purpose of the Study:

• To investigate whether human oral keratinocyte cells (HOKC) possess osteogenic capacity.
• To compare the bone-forming potential of BMP-transduced HOKC with BMP-transduced human gingival fibroblasts (HGF).
• To determine if HOKC undergo transdifferentiation into osteoblasts.

Main Methods:

• Transduction of HOKC and HGF with BMP-7 cDNA using recombinant adenoviruses.
• In vivo implantation of transduced cells to assess ectopic bone formation.
• Immunocytochemical analysis to detect keratin expression and cell localization.
• In vivo implantation within diffusion chambers to evaluate cell-autonomous bone formation.

Main Results:

• BMP-7-transduced HOKC formed ectopic ossicles, which were smaller and denser than those formed by HGF.
• Implanted HOKC were found adjacent to developing bone, confirmed by keratin expression.
• No bone-like tissue formed when HOKC were cultured in diffusion chambers, indicating a requirement for host cell interaction.

Conclusions:

• BMP-transduced HOKC can secrete BMP and induce ectopic bone formation in vivo.
• Unlike BMP-transduced HGF, HOKC do not appear to transdifferentiate into osteoblasts.
• These findings suggest that while HOKC can contribute to bone formation, their differentiation pathway differs from fibroblasts.