Improved functional assessment of osteoarthritic knee joint after chondrogenically induced cell treatment.

OBJECTIVES: Our previous studies on osteoarthritis (OA) revealed positive outcome after chondrogenically induced cells treatment. Presently, the functional improvements of these treated OA knee joints were quantified followed by evaluation of the mechanical properties of the engineered cartilages. METHODS: Baseline electromyogram (EMGs) were conducted at week 0 (pre-OA), on the locomotory muscles of nine un-castrated male sheep (Siamese long tail cross) divided into controls, adipose-derived stem cells (ADSCs) and bone marrow stem cells (BMSCs), before OA inductions. Subsequent recordings were performed at week 7 and week 31 which were post-OA and post-treatments. Afterwards, the compression tests of the regenerated cartilage were performed. RESULTS: Post-treatment EMG analysis revealed that the control sheep retained significant reductions in amplitudes at the right medial gluteus, vastus lateralis and bicep femoris, whereas BMSCs and ADSCs samples had no further significant reductions (P < 0.05). Grossly and histologically, the treated knee joints demonstrated the presence of regenerated neo cartilages evidenced by the fluorescence of PKH26 tracker. Based on the International Cartilage Repair Society scores (ICRS), they had significantly lower grades than the controls (P < 0.05). The compression moduli of the native cartilages and the engineered cartilages differed significantly at the tibia plateau, patella femoral groove and the patella; whereas at the medial femoral condyle, they had similar moduli of 0.69 MPa and 0.40-0.64 MPa respectively. Their compression strengths at all four regions were within ±10 MPa. CONCLUSION: The tissue engineered cartilages provided evidence of functional recoveries associated to the structural regenerations, and their mechanical properties were comparable with the native cartilage.

Engineering autogenous cartilage in the shape of a helix using an injectable hydrogel scaffold.

OBJECTIVE: Previous successful efforts to tissue engineer cartilage for an auricle have used an immunocompromised nude mouse xenograft model. Subsequent efforts in an immunocompetent autogenous animal model have been less successful because of an inflammatory response directed against the foreign scaffold polymer used to provide an auricular shape. We studied an alternative polymer material and surgical technique to engineer autogenous cartilage in the shape of a human ear helix using injectable hydrogel scaffolding, Pluronic F-127 (polyethylene oxide and polypropylene oxide). SUBJECT: Yorkshire swine. MATERIAL AND METHODS: Fresh autogenous chondrocytes were suspended in a biodegradable, biocompatible co-polymer hydrogel, Pluronic F-127, at a concentration of 3 x 10(7) cells/mL. To support the contour of the implant, a skin fold channel in the shape of the helix of a human ear was created in the skin in three sites on the ventral surface of the animal. The cell-hydrogel suspension was injected through the skin fold channel. For controls, injections were made into identical channels using either cells alone or the Pluronic F-127 without cells. After 10 weeks, the specimens were excised and examined both grossly and histologically. RESULTS: Grossly, all implants retained a helical-like shape. Excised specimens possessed flexible characteristics consistent with elastic cartilage. The specimens could be folded and twisted and on release of mechanical pressure would instantly return to the original shape. Histological evaluation of the implants using H&E, Safranin O, trichrome blue, and Verhoeff's stains demonstrated findings consistent with mature elastic cartilage. Control injection of hydrogel alone demonstrated no evidence of cartilage formation and control injection of chondrocytes alone showed evidence only of disassociated elastic cartilage. CONCLUSION: Injection of autologous porcine auricular chondrocytes suspended in a biodegradable, biocompatible hydrogel of Pluronic F-127 resulted in the formation of cartilage tissue in the approximate size and shape of a human ear helix. This preliminary method extends the concept of auricular tissue engineering from an immunocompromised xenograft animal model to an immunocompetent autologous animal model.