Combined effects of insulin-like growth factor-1 and transforming growth factor-β1 on periosteal mesenchymal cells during chondrogenesis in vitro

AbstractObjective Periosteum contains undifferentiated mesenchymal stem cells that have both chondrogenic and osteogenic potential, and has been used to repair articular cartilage defects. During this process, the role of growth factors that stimulate the periosteal mesenchymal cells toward chondrogenesis to regenerate articular cartilage and maintain its phenotype is not yet fully understood. In this study, we examined the effects of insulin-like growth factor-1 (IGF-1) and transforming growth factor-β1 (TGF-β1), alone and in combination, on periosteal chondrogenesis using an in vitro organ culture model.Methods Periosteal explants from the medial proximal tibia of 2-month-old rabbits were cultured in agarose under serum free conditions for up to 6 weeks. After culture the explants were weighed, assayed for cartilage production via Safranin O staining and histomorphometry, assessed for proliferation via proliferative cell nuclear antigen (PCNA) immunostaining, and assessed for type II collagen mRNA expression via in situ hybridization.Results IGF-1 significantly increased chondrogenesis in a dose-dependent manner when administered continuously throughout the culture period. Continuous IGF-1, in combination with TGF-β1 for the first 2 days, further enhanced overall total cartilage growth. Immunohistochemistry for PCNA revealed that combining IGF-1 with TGF-β1 gave the strongest proliferative stimulus early during chondrogenesis. In situ hybridization for type II collagen showed that continuous IGF-1 maintained type II collagen mRNA expression throughout the cambium layer from 2 to 6 weeks.Conclusion The results of this study demonstrate that IGF-1 and TGF-β1 can act in combination to regulate proliferation and differentiation of periosteal mesenchymal cells during chondrogenesis. Copyright 2003 OsteoArthritis Research Society International. Published by Elsevier Science Ltd. All rights reserved

Pretreatment of periosteum with TGF-β1 in situ enhances the quality of osteochondral tissue regenerated from transplanted periosteal grafts in adult rabbits

SummaryObjectiveTo compare the efficacy of in situ transforming growth factor-beta1 (TGF-β1)-pretreated periosteum to untreated periosteum for regeneration of osteochondral tissue in rabbits.MethodsIn the pretreatment group, 12 month-old New Zealand white rabbits received subperiosteal injections of 200ng of TGF-β1 percutaneously in the medial side of the proximal tibia, 7 days prior to surgery. Control rabbits received no treatment prior surgery. Osteochondral transverse defects measuring 5mm proximal to distal and spanning the entire width of the patellar groove were created and repaired with untreated or TGF-β1-pretreated periosteal grafts. Post-operatively the rabbits resumed normal cage activity for 6 weeks.ResultsComplete filling of the defects with regenerated tissue was observed in both the TGF-β1-pretreated and control groups with reformation of the original contours of the patellar groove. The total histological score (modified O’Driscoll) in the TGF-β1-pretreated group, 20 (95% Confidence Interval (CI), 19–21), was significantly higher (P=0.0001) than the control group, 18 (16–19). The most notable improvements were in structural integrity and subchondral bone regeneration. No significant differences in glycosaminoglycan or type II collagen content, or equilibrium modulus were found between the surgical groups. The cambium of the periosteum regenerated at the graft harvest site was significantly thicker (P=0.0065) in the TGF-β1-pretreated rabbits, 121μm (94–149), compared to controls, 74μm (52–96), after 6 weeks.ConclusionsThis study demonstrates that in situ pretreatment of periosteum with TGF-β1 improves osteochondral tissue regeneration at 6-weeks post-op compared to untreated periosteum in 12 month-old rabbits

An in vitro assessment of fibroblast and osteoblast response to alendronate-modified titanium and the potential for decreasing fibrous encapsulation

10.1089/ten.tea.2012.0218Tissue Engineering - Part A1917-181919-193