Role of oxygen tension during cartilage formation by periosteum

Abstract

Tissue engineering makes regeneration of cartilage possible but requires optimization of culture conditions. The effects of oxygen tension on cartilage metabolism are controversial in the literature, and we could find no information detailing the optimal oxygen concentration for growing new cartilage (neochondrogenesis). Periosteal cells and tissues can be used to grow cartilage in vivo and in vitro. In this study, using a standard periosteal organ culture model, we found that cartilage formation by periosteal explants is affected by the ambient oxygen concentrations. A total of 480 periosteal explants from 30 2-month-old New Zealand White rabbits were cultured in agarose suspension at different oxygen concentrations (1-90%) for 6 weeks. Chondrogenesis, which was analyzed by histomorphometry and quantitative collagen typing, was maximal at 12-15% oxygen. There were no significant differences in chondrogenesis in the range of 12-45%. There was inhibition of cartilage and type-II collagen formation at very high (90%) and very low (1-5%) oxygen concentrations. However, contrary to what some have thought, chondrogenesis is maximal under aerobic conditions. If this is true for systems other than periosteal implants, it would have important implications for growing cartilage in vitro.

Gas exchange is essential for bioreactor cultivation of tissue engineered cartilage

“…Oxygen tensions of 78-180 mmHg increased GAG synthesis by 2-fold in explants of steer articular cartilage as compared to physiological p O 2 (45 mmHg) (Ysart and Mason, 1994). Similarly, oxygen tensions of 91-114 mmHg enhanced cartilage tissue formation and increased the amount of collagen type II in rabbit periosteal explants cultured in agarose suspension, as compared to p O 2 of 8-38 mmHg which inhibited ECM formation (O'Driscoll et al, 1997). For monolayers of bovine growth plate chondrocytes, highest rates of cell growth and GAG synthesis were observed at p O 2 of 160 mmHg; GAG production rate decreased while the rate of proteoglycan aggregation increased at p O 2 of 22.8 mmHg (Clark et al, 1991).…”

Serum‐free media for periosteal chondrogenesis in vitro

“…The potentiating effect of TGF-P1 on periosteal chondrogenesis, when administered in the presence of fetal bovine serum, is well established [15,30,35,36,42,56,57]. Yaeger et al in developing serum-free media for culturing articular chondrocytes in suspension, found that neither TGF-Pl nor IGF-1 on their own could support the expression of the chondrocyte phenotype, however, the combination of these two growth factors did support the chondrocyte phenotype [69].…”

“…Periosteum transplanted into a joint has the potential to repair articular defects with hyaline-like cartilage [32,37,38,42,. This same chondrogenic potential can be demonstrated in vitro [15,30,35,36,42,56,57]. However, the standard organ culture model to date involving whole explants of periosteum has required the addition of fetal bovine serum to the media.…”

“…Experimental models involving cell or tissue culture of chondrocytes or chondrogenic cells have demonstrated the feasibility of growing cartilage in vitro. These include, but are not limited to, the use of chondrocytes [3,16,17], mesenchymal stem cells [ 18, 19,67] and whole tissues such as periosteum [ 15,30,35,36,42,56,57] or perichondrium [1, 2,5,7,[9][10][11][12]21,46,47,50,58,59,65] genesis. Many of these systems have relied on the use of fetal bovine serum in the medium.…”

Expression of human bone morphogenic protein 7 in primary rabbit periosteal cells: potential utility in gene therapy for osteochondral repair

“…Other groups studying cartilage repair have recently demonstrated the ability to transfer and express genes in chondrocytes in vivo in cartilage defect models 25,26 while another study has used nongene-modified periosteal cells in cartilage repair models. 27 In an attempt to develop a gene therapy approach for bone and cartilage repair by delivering a clinically relevant gene, we have demonstrated that retroviral vectormediated delivery of the hBMP-7 gene can be used to transduce primary periosteal cells in vitro. However, our results demonstrate the importance of preventing overexpression of hBMP-7 in target cells due to its apparent toxicity.…”