engleski

Regeneration of larynx cartilage by osteogenic protein -1

Introduction: Bone morphogenetic proteins (BMPs) form a novel family of growth factors under transforming growth factor -b (TGF-b) superfamily. They were isolated from bone matrix by their ability to induce new bone in adult organisms recapitulating cellular events involved in the formation of skeleton during embrionic development. There is a high believe but little evidence that the same morphogens (BMPs) are capable for de novo formation of bone, cartilage, ligament, tendon and periodontal tissues. We examined their efficacy in regeneration of dog laringeal skeleton by treating thyroid cartilage defects with human recombinant BMP-7 (OP-1) delivered via two different delivery sistems (thyroid allograft or collagen sponge). Methods: Experiment was performed on 15 young beagle dogs. Defects were created by cutting out quadrangle area of thyroid cartilage lamina (1.5 cm2). Thyroid allografts used for closing the defect were previously prepared by freezing and thawing procedure and demineralized with acid. Prior to implantation allografts were soaked with 500 or 100mg rhOP-1 or left untreated (control). In one group, allografts were additionally extracted with guanidine HCl and salt. Allografts were fixed with sutures and closed with perichondrium. Collagen sponges (Helistat) used in experiment were soaked with OP-1 and covered with perichondrium. Dogs were sacrefied four months after surgery. Each larynx was dissected and a three dimensional reconstruction was performed on serial sections. Results: Control dog implants were unchanged in shape and size and without new tissue formation. OP-1 enriched allografts dose dependently induced new bone, cartilage and ligament like tissue, regardless of allograft preparation method. Defects treated with collagen sponge soaked with OP-1, also induced formation of solid tissue. New formed tissue comprised up to 80% of the total regenerated area. Disscusion: New solid tissues induced by OP-1 in our study were well integrated into neighbouring old cartilage and met mechanical needs for swallowing, breathing and barking. This indicates that OP-1 in apropriate delivery sistem could provide an additional option for laryngotracheal reconstruction. Conclusion: The three newly formed tissue were tightly connected into a "bone-cartilage-ligament continuum" suggesting that OP-1 served as multiple tissue morphogen in this specific microenvironment.

osteogenic protein -1; cartilage regeneration

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