Cartilage tissue engineering

Cartilage has a poor regenerative potential with very low cell-density that contributes to its poor capability for self-repair .For this reason, autologous cartilage grafts have been used in reconstructive surgery .Today; the rapidly emerging field of tissue engineering holds great promises for the generation of functional cartilage tissue substitutes. The technique was initiated by harvesting cartilage cells [chondrocytes] from a donor site such as the nasal septum or the auricle. However, in clinical use of human chondrocytes for tissue engineering, extensive expansion of cell numbers from a small donor site biopsy was required and this could limit the chondrogenic potential of cells after proliferation. Therefore, the ability of chondrocytes to replicate in- vitro allowed the expansion of cell numbers to produce theoretically limitless supplies of cartilage autografts .Stem cell technology presents an alternative, immunoprivileged resource of cells with unlimited replicative capacity. These cells exist in a wide selection of tissues and provide the option of multi-lineage differentiation. This paper reviews the current evidence that stem cells may provide a superior cell resource for tissue engineered cartilage and outlines the methodology for their isolation and chondrogenic induction

Evaluation of vascular access using cryopreserved jugular vein [experimental study]

Background: While considering the rise in the mean age of the chronic renal failure [CRF] patients and increasing frequency of those who need constant hemodialysis, the creation of a native arteriovenous fistula [AVF] is not possible, which could be due to the inaccessibility of the superficial veins. This study was conducted to evaluate the efficacy of the vascular access, using cryopreserved jugular vein

Materials and Methods: In this experimental study, 15 sheep [Wt.= 30-40 kg] were selected between the year 2001 and 2002. The external jugular vein of each sheep was excised and after cryopreservation was put in liquid nitrogen [-196°C]. Twenty-eight days later, the sample veins were used as allograft [in another sheep], and autograft [in the same sheep] and were placed between carotid artery and external jugular vein as bridge AVF. The efficacy, function, and patency were evaluated using doppler sonography and pathologic report

Results: Patency rate of sample was 100% after 3 months in both allografts and autografts. Thrombosis, hematoma, and infection were not seen. No inflammation was detected in pathologic report

Conclusion: This study showed that using allograft vein for vascular access is feasible and suitable, and it is recommended specially for those with previously infected fistula