Parallel changes in fibronectin and alpha5beta1 integrin in articular cartilage in type II collagen-induced arthritis.

Interactions of cells with extracellular matrix (ECM) are mediated through specific cell surface receptors, belonging to the integrin family of transmembrane proteins. Integrins have been shown to be involved in chondrocyte-matrix interactions in the cartilage. In this study, the status of a matrix glycoprotein fibronectin (FN) and its receptor alpha5beta1 integrin in the articular cartilage in collagen type II-induced experimental arthritis in rats, as well as in synovial fluid from osteoarthritic patients was investigated. Experimental arthritis was induced by intradermal injection of type-II collagen (300 microg/100 g body wt) and Freund's complete adjuvant. Saline-treated animals served as control. Clinical severity was indicated by increase in paw volume. Significant increase in the activities of lysosomal enzymes beta-glucuronidase and beta-hexosaminidase was observed in synovial effusate, serum and cartilage of arthritic animals, when compared to untreated control, indicating dysfunction of cartilage. Changes in FN and alpha5beta1 integrin were studied by ELISA. A progressive increase was observed in the FN level in synovial effusate and cartilage of arthritic animals, when compared to untreated controls. FN levels were also significantly high in synovial fluid of osteoarthritic patients. A significant increase in the levels of alpha5beta1 integrin was found in cartilage of arthritic rats. Parallel changes in FN and alpha5beta1 integrin indicated that alterations in FN and alpha5beta1 integrin in chondrocytes constituted one of the molecular mechanisms during progression of arthritis.

Stem Cells Expressing Homing Receptors Could be Expanded From Cryopreserved and Unselected Cord Blood

We assessed the cytokine combinations that are best for ex vivo expansion of cord blood (CB) and the increment for cell numbers of nucleated cells, as well as stem cells expressing homing receptors, by an ex vivo expansion of cryopreserved and unselected CB. Frozen leukocyte concentrates (LC) from CB were thawed and cultured at a concentration of 1x10(5)/mL in media supplemented with a combination of SCF (20 ng/mL)+TPO (50 ng/mL)+FL (50 ng/mL)+/-IL-6 (20 ng/mL)+/-G-CSF (20 ng/mL). After culturing for 14 days, the expansion folds of cell numbers were as follows: TNC 22.3+/-7.8~26.3+/-4.9, CFU-GM 4.7+/-5.1~11.7+/-2.6, CD34+CD38- cell 214.0+/-251.9~464.1+/-566.1, CD34+CXCR4+ cell 4384.5+/-1664.7~7087.2+/-4669.3, CD34+VLA4+ cell 1444.3+/-1264.0~2074.9+/-1537.0, CD34+VLA5+ cell 86.2+/-50.9~ 113.2+/-57.1. These results revealed that the number of stem cells expressing homing receptors could be increased by an ex vivo expansion of cryopreserved and unselected CB using 3 cytokines (SCF, TPO, FL) only. Further in vivo studies regarding the engraftment after expansion of the nucleated cells, as well as the stem cells expressing homing receptors will be required.