The Effect of Growth Factors and Synovial Fluid on Chondrogenesis in Perichondrium

Abstract

Reconstruction of cartilage with perichondrium depends on the chondrogenic property of the perichondrial fibrocytes. The present investigation concerns the conditions for the differentiation of fibrocytes into chondrocytes both in vivo and in vitro. For the in vivo studies specimens of rib and auricular perichondrium from adult rabbits were wrapped round silicon rods which were enclosed in dialysis bags. One was placed in the suprapatellar pouch of the knee joint and one was placed intraperitoneally in each rabbit. After two months the bags were extracted, the perichondrium prepared for microscopic examination, and the chondrogenesis evaluated. In vitro the perichondrium was divided into small pieces and incubated with tissue culture medium. The medium was supplemented with fetal calf serum, together with epidermal growth factor, platelet derived growth factor, synovial fluid, or with human serum albumin (control group). After three weeks the explants were prepared for microscopy. Chondrogenesis was judged by the degree of cellular enlargement, capsule formation, deposition of matrix, and activation of the outer fibrocytic layer. In vivo, good cartilage development was found in all specimens placed in the knee joint but, in those placed intraperitoneally, little if any chondrogenesis was seen. In vitro profound differentiation occurred in all cultures supplemented with epidermal growth factor and platelet derived growth factor. An equivalent differentiation was found in perichondrium that had been incubated with synovial fluid. We conclude that the differentiation of perichondrial fibrocytes is initiated in vitro by growth factors. In addition, we have shown that synovial fluid contains factors that promote and enhance the development of cartilage from perichondrium.

Compound heterozygous loss of Ext1 and Ext2 is sufficient for formation of multiple exostoses in mouse ribs and long bones

“…However, because Col2Cre and Dermo1Cre target both chondrocytes and perichondrial cells, the data do not allow us to identify conclusively the exact nature of the outgrowth-forming cells. A perichondrial origin of exostosis-forming cells would be particularly attractive because the perichondrium contains cells of mesenchymal origin that can differentiate into chondrocytes and osteoblasts and participate in radial bone growth and fracture healing [51, 52]. Thus, we should certainly entertain the idea that exostoses may in fact arise from heparan sulfate deficiency in a stem cell population.…”

The secreted glycoprotein lubricin protects cartilage surfaces and inhibits synovial cell overgrowth

“…In the case of the superficial chondrocytes, 2 non-mutually exclusive mechanisms could be responsible: (a) direct damage to the cells because of increased friction and (b) restricted access of these cells to nutrients or vital growth factors because of the abnormal protein deposition ( Figure 5). Synovial fluid contains growth factors that affect chondrocyte growth (27). Deeper chondrocytes may initially be protected because of their surrounding matrix and lower metabolic rate.…”

Chondrogenic Potential ofin VitroMultiplied Rabbit Perichondrium Cells Cultured in Alginate Beads in Defined Medium

“…Moreover, chondrogenic differentiation seems to be influenced by growth factors. [14][15][16][17][18][19][20] Although stimulating effects of transforming growth factor-b (TGF-b ) have been found in cartilage formation from periosteum-derived cells, 15,[19][20][21][22] the effects of TGF-b are reported to depend on the presence of serum. 23,24 In addition, re-expression of the cartilaginous phenotype of multiplied (dedifferentiated) chondrocytes has been demonstrated to vary considerably between different serum batches.…”