Effects of microcurrent stimulation on hyaline cartilage repair in immature male rats (Rattus norvegicus).

BACKGROUND: In this study, we investigate the effects of microcurrent stimulation on the repair process of xiphoid cartilage in 45-days-old rats. METHODS: Twenty male rats were divided into a control group and a treated group. A 3-mm defect was then created with a punch in anesthetized animals. In the treated group, animals were submitted to daily applications of a biphasic square pulse microgalvanic continuous electrical current during 5 min. In each application, it was used a frequency of 0.3 Hz and intensity of 20 µA. The animals were sacrificed at 7, 21 and 35 days after injury for structural analysis. RESULTS: Basophilia increased gradually in control animals during the experimental period. In treated animals, newly formed cartilage was observed on days 21 and 35. No statistically significant differences in birefringent collagen fibers were seen between groups at any of the time points. Treated animals presented a statistically larger number of chondroblasts. Calcification points were observed in treated animals on day 35. Ultrastructural analysis revealed differences in cell and matrix characteristics between the two groups. Chondrocyte-like cells were seen in control animals only after 35 days, whereas they were present in treated animals as early as by day 21. The number of cuprolinic blue-stained proteoglycans was statistically higher in treated animals on days 21 and 35. CONCLUSION: We conclude that microcurrent stimulation accelerates the cartilage repair in non-articular site from prepuberal animals.

Can one generate stable hyaline cartilage from adult mesenchymal stem cells? A developmental approach.

Chondrogenically differentiating bone marrow-derived mesenchymal stem cells (BMSCs) display signs of chondrocyte hypertrophy, such as production of collagen type X, MMP13 and alkaline phosphatase (ALPL). For cartilage reconstructions this is undesirable, as terminally differentiated cartilage produced by BMSCs mineralizes when implanted in vivo. Terminal differentiation is not restricted to BMSCs but is also encountered in chondrogenic differentiation of adipose-derived mesenchymal stem cells (MSCs) as well as embryonic stem cells, which by definition should be able to generate all types of tissues, including stable cartilage. Therefore, we propose that the currently used culture conditions may drive the cells towards terminal differentiation. In this manuscript we aim to review the literature, supplemented by our own data to answer the question, is it possible to generate stable hyaline cartilage from adult MSCs? We demonstrate that recently published methods for inhibiting terminal differentiation (through PTHrP, MMP13 or blocking phosphorylation of Smad1/5/8) result in cartilage formation with reduction of hypertrophic markers, although this does not reach the low level of stable chondrocytes. A set of hypertrophy markers should be included in future studies to characterize the phenotype more precisely. Finally, we used what is currently known in developmental biology about the differential development of hyaline and terminally differentiated cartilage to provide thought and insights to change current culture models for creating hyaline cartilage. Inhibiting terminal differentiation may not result in stable hyaline cartilage if the right balance of signals has not been created from the start of culture onwards.

Pulsed electromagnetic field therapy results in healing of full thickness articular cartilage defect.

This study aimed to determine the efficacy of PEMF (pulsed electromagnetic field) treatment in experimental osteochondral defect healing in a rabbit model. The study was conducted on 12 New Zealand white rabbits. Six rabbits formed the study group and six rabbits the control group. The right knee joints of all 12 animals were exposed and a 3.5-mm diameter osteochondral defect was created in the trochlear groove. The defect was filled with calcium phosphate scaffold. Six animals from the study group were given PEMF of one hour duration once a day for six weeks with set parameters for frequency of 1 Hz, voltage 20 V, sine wave and current ±30 mA. At six weeks the animals were sacrificed and histological evaluation was done using H&E, Safranin O, Maissons trichrome staining and immunohistochemistry for type 2 collagen. The quality of the repair tissue was graded and compared between groups with the Wakitani histological grading scale and a statistical analysis was done. The total histological score was significantly better in the study group (p = 0.002) with regeneration similar to adjacent normal hyaline cartilage. Immunohistochemistry for collagen type II was positive in the study group. PEMF stimulation of osteochondral defects with calcium phosphate scaffold is effective in hyaline cartilage formation. PEMF is a non-invasive and cost effective adjuvant treatment with salvage procedures such as abrasion chondroplasty and subchondral drilling.

Sulfasalazine blocks the release of proteoglycan and collagen from cytokine stimulated cartilage and down-regulates metalloproteinases.

OBJECTIVE: To investigate the effect of SSZ on the release of GAG and collagen fragments from bovine nasal cartilage and MMP and ADAMTS (a disintegrin and metalloproteinase domain with thrombospondin motifs) proteinases from human articular chondrocytes (HACs) stimulated with IL-1alpha and oncostatin M (OSM). METHODS: SSZ was added to bovine nasal explant cultures stimulated to resorb with IL-1alpha and OSM, and the release of GAG and collagen has been determined. Collagenolytic activity was measured using the radio-labelled collagen bioassay. HACs were treated with IL-1alpha and OSM with and without SSZ, and MMP-1 and -13 and ADAMTS-4 and -5 were measured for protein and gene expression by ELISA and RT-PCR, respectively. RESULTS: SSZ blocked GAG and collagen fragment release from bovine cartilage, and reduced active and total collagenase activity in a dose-dependent manner. SSZ transcriptionally blocked MMP-1, -13 and ADAMTS-4, and reduced the protein levels of MMP-1 and -13 in a dose-dependent manner following stimulation of HACs with IL-1alpha and OSM. CONCLUSION: This study shows for the first time that SSZ blocks release of proteoglycan and collagen fragments from resorbing cartilage and lowers the levels of proteoglycan and collagen-degrading enzymes. These results indicate that in addition to acting as an anti-inflammatory agent, SSZ may have a therapeutic role in protecting cartilage from damage in OA.

Insulin-transferrin-selenium prevent human chondrocyte dedifferentiation and promote the formation of high quality tissue engineered human hyaline cartilage.

This study was to investigate the effects of insulin-transferrin-selenium (ITS) on the proliferation and quantitative gene expression of adult human nasal septum chondrocytes in monolayer culture expansion and the formation of tissue engineered hyaline cartilage. Effects of ITS on human nasal septum chondrocytes monolayer culture expansion and gene expression were evaluated in various culture media either added with 2% fetal bovine serum (FBS) or 1 ng/mL basic fibroblast growth factor plus 1 ng/mL transforming growth factor or both serum and growth factors supplementation in comparison with medium added with 10%FBS. Chondrocytes cultured in medium added with 2% fetal bovine serum and growth factors either supplemented with or without ITS were then mixed with pluronic F-127 hydrogel for in vivo tissue engineered cartilage formation in nude mice model. Engineered tissues were removed after 8 weeks of implantation and evaluated with histological staining, immunohistochemistry, transmission electron microscopy and quantitative gene expression analysis. ITS promoted human chondrocytes proliferation and reduced chondrocytes dedifferentiation in media supplemented with serum and growth factors. ITS with 2% FBS and growth factors provided 15-fold increased in chondrocytes number by the end of the culture period compared to the standard culture medium used in chondrocytes culture (medium added with 10% FBS). Engineered tissue resulted from ITS supplementation demonstrated higher quality of cartilage formation. In conclusion, our study has demonstrated the benefits of ITS supplementation in human chondrocytes monolayer culture and tissue engineering cartilage formation.