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Stem Cell-based Cartilage Repair
Chondrocyte-based therapies have been extensively studied since the successful report of autologous chondrocyte implantation by Brittberg and Peterson. However, this procedure may have limitations, including the sacrifice of undamaged cartilage within the same joint and dedifferentiation associated with the ex vivo expansion of the cells. Furthermore, due to the degenerative changes in cartilage accompanying aging, the viability biologic potential of the cells may be limited in elderly individuals. To overcome such potential problems, stem cell therapies have become a focus to facilitate regenerative tissue repair. Mesenchymal stem cells (MSCs) have the capability to differentiate into a variety of connective tissue cells including bone, cartilage, tendon, muscle, and adipose tissue and can be isolated from various tissues. There have been several reports of clinical trials of stem cell-based cartilage repair. As a potential method, a scaffold-free three-dimensional tissue engineered construct (TEC) derived from synovial MSCs has been generated. Followed by the preclinical study, “First-in-men” clinical trial was started at the Osaka University Hospital which has a GMP-grade cell processing center in 2013. Preliminary results suggest the TEC could efficiently promote cartilage repair assessed by arthroscopy and magnetic resonance imaging (MRI) (conventional and quantitative such as T2 mapping) at 12 months (Fig. 8). This clinical study will be completed by March 2015.
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In summary, treatment of patellofemoral articular cartilage lesions remains a challenging clinical entity. Regardless of the procedure chosen to treat these lesions, identifying and correcting all contributing factors such as patellar trochlear mal-alignment and reducing contact stresses are essential for a successful outcome. Future research into biologically optimizing the environment for hyaline cartilage growth may serve to improve the results of our currently used methods.
CURRENT CONCEPTS
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01 Fig 1a
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Preoperative x-ray demonstrating trochlear dysplasia. Intraoperative x-ray demonstrating correction of dysplastic trochlear spur (TTO and MPFL guide also visualized). Intraoperative photograph demonstrating 2 cm lateral retinacular lengthening.
Intraoperative arthroscopy demonstrating microfracture of a patellar cartilage lesion with flow of marrow elements from subchondral bone.
Intraoperative photograph of microfracture with micronized cartilage allograft and fibrin glue.
Intraoperative photograph of autologous chondrocytes being injected under collagen I/III membrane.
Intraoperative photograph showing juvenile particulated chondral allograft implanted under a collagen membrane in a patella cartilage defect
Intraoperative photograph of a lateral trochlear OCD lesion treated with 2 fresh stored osteochondral transplanted dowels (snowman technique).
Arthroscopic views of the pre-operation defect (Left) and
1 year after implantation of a TEC (Right) with corresponding T2 mapping of the lesion
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ISAKOS NEWSLETTER 2015: Volume I 33