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Purpose: This study was to investigate the cytotoxic potency of local anesthetics on human mesenchymal stem cells during chondrogenesis., Methods: Aggregates were created from density-gradient centrifugation-separated bone marrow-derived mesenchymal stem cells. After 7, 14, and 21 days, aggregates were analyzed histologically and immunohistochemically and exposed to equipotent concentrations of bupivacaine, ropivacaine, and mepivacaine for 1 h. Cell viability, apoptosis, and necrosis were determined using live-dead and caspase staining. Additionally, following a 1-h exposure on day 7, aggregates were cultured under chondrogenic conditions until day 21 to assess the effects of local anesthetics on differentiation potency of mesenchymal stem cells., Results: In the course of chondrogenesis, mesenchymal stem cells were embedded in varying amount and structure of cartilage-specific extracellular matrix. Contents of sulfated glycosaminoglycan, type I and II collagen increased from day 7 to day 21. Compared to control, death rates of mesenchymal stem cells were significantly elevated 1 day after treatment at 7 and 14 days. Four days after exposure, death rates were 13-15 % at 7 and 11-17 % at 14 days. Mesenchymal stem cell viability in aggregates at 21 days was unchanged to controls. The width of the superficial aggregate zone containing stem cell necrosis decreased with elongated differentiation time. Apoptosis rates were elevated in the edge regions of aggregates, reaching maximum values 4 days after treatment. Local anesthetic exposure on day 7 reduced Collagen II, but not DNA contents in aggregates at 21 days. Bupivacaine, ropivacaine, and mepivacaine did not differ in mesenchymal stem cell cytotoxicity in aggregates., Conclusion: Local anesthetic exposure results in cytotoxicity of mesenchymal stem cells undergoing chondrogenesis, especially in superficial layers. Therefore, induced cell damage should be avoided during chondrogenesis of mesenchymal stem cells, particularly early after cartilage repair.

Background: The application of radiofrequency energy (RFE) has become widespread for surgical performed chondroplasty especially due to the anticipated sealing effect, however the safety of this procedure in the wrist remains unclear. The purpose of this study was to investigate the subchondral temperature during radiofrequency energy (RFE) application simulating chondroplasty in an arthroscopic setting of the wrist., Methods: A chondroplasty of the lunate fossa was performed during an arthroscopy setting on 14 cadaver arms using monopolar or bipolar RFE. The temperature was recorded simultaneously from 7 predefined anatomical landmarks., Results: The mean temperature for both application modes did not exceed more than 30°C at all measured points, except for the lunate fossa. The highest subchondral measured peak temperature was 49.35°C (monopolar) and 69.21°C (bipolar) in the lunate fossa. In addition, the temperature decreased for both radiofrequency (RF) devices depending on the distance of the sensors to the RF-probe., Conclusion: It remains to be questionable how safe RFE can be used for chondroplasty in wrist arthroscopy under continuous irrigation and constant movement to obtain the desired sealing effect. However, the bipolar device should be applied with more caution since peak temperature in the lunate fossa almost reached 70°C even under continuous irrigation.

Background: Matrix-guided autologous chondrocyte transplantation (MACT) has been proposed as an option for treating large full-thickness cartilage defects. However, little is known about the chondrogenic potential of transplants for MACT at the time of implantation, although cell quality and chondrogenic differentiation of the implants are crucial for restoration of function after MACT., Questions/purposes: We therefore asked: (1) Do MACT implants allow deposition of extracellular cartilage matrix in an in vitro culture model? (2) Are these implants associated with improved knee function 1 year after MACT in large cartilage defects?, Methods: We retrospectively reviewed all 125 patients with large localized cartilage defects (mean defect size 5 cm(2)) of the knee who were treated with MACT from 2005 to 2010. The mean age was 31 years (range, 16-53 years). Portions of the cell-matrix constructs (n = 50) that were not implanted in the cartilage defects were further cultured and tested for their potential to form articular cartilage. Knee function of all patients was analyzed preoperatively, 3 months, and 1 year postoperatively with the International Knee Documentation Committee (IKDC) score., Results: In vitro assessment of the cell-matrix implants showed chondrogenic differentiation with positive staining for glycosaminoglycans and collagen II in all cultures. Enzyme-linked immunosorbent assay showed an increase of collagen II production. We observed an improvement in median IKDC score from 41 to 67 points at last followup., Conclusions: Cartilage extracellular matrix deposition shows adequate implant quality for MACT at the time of implantation and justifies the use for treatment of large cartilage defects.

Decreasing replicative potential and dedifferentiation of articular chondrocytes during expansion in cell culture are essential limitations for tissue engineering and cell therapy approaches. Telomeres and telomerase play a key role in cell development, aging, and tumorigenesis. There is evidence that growth factors are involved in regulating telomerase activity. Therefore, the objective was to evaluate the effect of selected growth factors on telomere biology of serially passaged chondrocytes. Human articular chondrocytes were isolated from cartilage of three patients undergoing total knee arthroplasty. The chondrocytes were cultured in monolayer with the growth factors PDGF-BB, TGF-beta1, and bFGF. Telomere length was measured by telomere restriction fragment length assay, and telomerase activity was determined by quantifying the gene expression of its catalytic subunit hTERT by rtPCR. Chondrocytes cultured with PDGF-BB and TGF-beta1 showed a significantly higher proliferation rate than control cells. None of the growth factor cultures revealed an accelerated rate of telomere shortening. Telomerase was not expressed in significant amounts in any of the chondrocyte cultures. Growth factor treatment of chondrocyte cell cultures for cell therapy purposes can be regarded as safe in terms of telomere biology.

Microangiographic investigation of the glenoid labrum of the dog shows a rich vascular supply to the labrum except for its free edge. The vessels originate predominantly from the shoulder joint capsule and periosteum of the scapula neck. Several anastomoses to the glenoid vessels were demonstrated. This rich vascularization provides a good environment for surgical repair of traumatically detached parts of the labrum.