Expression of collagen type I, II and III in loose body of osteoarthritis

Stem cells immortalized by hTERT perform differently from those immortalized by SV40LT in proliferation, differentiation, and reconstruction of matrix microenvironment

Although matrix microenvironment has the potential to improve expanded stem cell proliferation and differentiation capacity, decellularized extracellular matrix (dECM) deposited by senescent cells does not contribute to the rejuvenation of adult stem cells, which has become a barrier to personalized stem cell therapy. Genetic modification is an effective strategy to protect cells from senescence but it carries the increased risk of malignant transformation and genetic instability. In this study, lentivirus carrying either human telomerase reverse transcriptase (hTERT) or simian virus 40 large T antigen (SV40LT) was used to transduce human infrapatellar fat pad-derived stem cells (IPFSCs). We found that virus transduction modified the proliferative, chondrogenic, and adipogenic abilities of IPFSCs. Interestingly, dECM deposited by immortalized cells significantly influenced replicative senescent IPFSCs in proliferation and differentiation preference, the effect of which is hinged on the approach of immortalization using either SV40LT or hTERT. Our findings indicate both dECM expansion and immortalization strategies can be used for replicative senescent adult stem cells' proliferation and lineage-specific differentiation, which benefits future stem cell-based tissue regeneration. This approach may also work for adult stem cells with premature senescence in elderly/aged patients, which needs further investigation. STATEMENT OF SIGNIFICANCE: Adult stem cells are a promising solution for autologous cell-based therapy. Unfortunately, cell senescence due to donor age and/or ex vivo expansion prevents clinical application. Recent progress with decellularized extracellular matrix provides a potential for the rejuvenation of senescent stem cells by improving their proliferation and differentiation capacities. Given the fact that the young matrix can provide a healthy and energetic microenvironment, in this study, two approaches using lentivirus transduction of hTERT and SV40LT were compared. The goal was to immortalize donor cells for deposition of decellularized extracellular matrix. The matrix was demonstrated to contribute diverging effects on the chondrogenic and adipogenic differentiation of expanded stem cells and exhibited proliferation benefits as well. These findings provide an invaluable asset for stem cell-based tissue regeneration.

Local Tensile Stress in the Development of Posttraumatic Osteoarthritis

The pathogenesis of posttraumatic osteoarthritis (PTOA) remains unrevealed. We speculate that cartilage crack caused by joint trauma will induce local abnormal tensile stress, leading to change in extracellular matrix (ECM) expression of chondrocytes, cartilage degeneration, and initiation of osteoarthritis. Finite element model was used to examine whether the local tensile stress could be produced around the crack. Cell experiments were conducted to test the effect of tensile strain on chondrocyte ECM expression. Animal tests in rabbits were carried out to examine the change around the cartilage crack. The results indicated that the local tensile stress was generated around the crack and varied with the crack angles. The maximum principal tensile stress was 0.59 MPa around the 45° crack, and no tensile stress was found at 90°. 10% tensile strain could significantly promote type I collagen mRNA expression and inhibit type II collagen and aggrecan (the proteoglycan core protein) mRNA expression. Type I collagen was detected around the 45° crack region in the cartilage with no change in type II collagen and proteoglycan. We conclude that the local tensile stress produced around the cartilage crack can cause the change in cartilage matrix expression which might lead to cartilage degeneration and initiation of osteoarthritis. This study provides biomechanical-based insight into the pathogenesis of PTOA and potentially new intervention in prevention and treatment of PTOA.

Arthroscopic treatment of bony loose bodies in the subacromial space

INTRODUCTION

Multiple bony loose bodies in the subacromial space caused form cartilage or bone cells and continue to grow.

PRESENTATION OF CASE

A 58-year-old man with two-year history of swelling and pain of the right shoulder. He had no history of tuberculosis and rheumatoid arthritis. Magnetic resonance (MR) images showed some bony loose bodies in the subacromial space. The removal of loose bodies and bursa debridement were performed arthroscopically. Histological diagnosis of them was synovitis with fibrous bodies.

DISCUSSION

Extra-articular loose bodies is extremely rare, especially in the subacromial space, which maybe originated in the proliferative synovial bursa. Most authors recommend open removal to relive the pain, but there were choice to apply arthroscopy to remove them.

CONCLUSION

The mechanism of formation of bony loose bodies is not clear, may be associated with synovial cartilage metaplasia. Arthroscopic removal of loose bodies and bursa debridement is a good option for treatment of the loose body in the subacromial space, which can receive good function.

Effects of Collagen Tripeptide Supplement on Photoaging and Epidermal Skin Barrier in UVB-exposed Hairless Mice

Collagen tripeptide (CTP) is a functional food material with several biological effects such as improving dry skin and wound and bone fracture healing. This study focused on the anti-photoaging effects of CTP on a hairless mouse model. To evaluate the effects of CTP on UVB-induced skin wrinkle formation in vivo, the hairless mice were exposed to UVB radiation with oral administration of CTP for 14 weeks. Compared with the untreated UVB control group, mice treated with CTP showed significantly reduced wrinkle formation, skin thickening, and transepidermal water loss (TEWL). Skin hydration and hydroxyproline were increased in the CTP-treated group. Moreover, oral administration of CTP prevented UVB-induced MMP-3 and -13 activities as well as MMP-2 and -9 expressions. Oral administration of CTP increased skin elasticity and decreased abnormal elastic fiber formation. Erythema was also decreased in the CTP-treated group. Taken together, these results strongly suggest that CTP has potential as an anti-photoaging agent.

Type II TGFβ receptor modulates chondrocyte phenotype

Aging is one of the major risk factors of osteoarthritis. This pathology during which chondrocytes undergo modifications of their phenotype may result from alteration of transforming growth factor β (TGFβ) signaling. This study investigates the role of TGFβ response in the process of chondrocyte dedifferentiation/redifferentiation. Dedifferentiation was induced by successive passages of human articular chondrocytes, whereas their redifferentiation was performed by three-dimensional culture in alginate. Human mesenchymal stem cells were obtained from bone marrow and differentiated into chondrocyte-like phenotype by three-dimensional culture, embedded in the same scaffold. Protein and mRNA levels were analyzed by Western blot and real-time reverse transcription PCR. Regulatory mechanism was investigated using specific inhibitors (mithramycin), mRNA silencing or decoy oligonucleotides, and expression vectors. Chondrocyte dedifferentiation interfered with TGFβ signaling by decreasing TβRII mRNA and protein levels and subsequent TGFβ response. TβRII ectopic expression in passaged chondrocytes permitted to increase the expression of several matrix genes, such as aggrecan or type II collagen. Redifferentiation of passaged chondrocytes permitted to restore, at least in part, TβRII expression and was related to differentiation of human bone marrow mesenchymal stem cells toward chondrocytes, where both specific protein 1 (Sp1) and TβRII mRNA levels were increased. Moreover, Sp1 manipulation by silencing or ectopic expression and pharmacologic inhibition revealed a link between expression levels of this transcriptional factor, which is crucial for constitutive expression of TβRII in cartilage, and TGFβ response. Therefore, these data permit us to suggest an important role of TβRII expression in the maintenance of chondrocyte phenotype, which is altered with age, and bring new insights in our understanding of chondrogenesis process.

Comparison between loose fragment chondrocytes and condyle fibrochondrocytes in cellular proliferation and redifferentiation

BACKGROUND

Loose fragments in spontaneous osteonecrosis of the knee (SONK) are usually removed by surgical treatment. However, the healing potential of osteonecrotic loose fragments and their clinical availability, for example as a cell source for cartilage repair and tissue engineering, have not been investigated. The objective of this study was to evaluate the cellular proliferation and redifferentiation ability of loose fragment chondrocytes for the treatment of SONK.

METHODS

Cells were obtained from the remaining cartilage of chondral loose fragments or fibrocartilaginous tissue under the affected femoral condyle in SONK. The proliferation activity of loose fragment-derived chondrocytes and condyle-derived fibrochondrocytes was evaluated. In-vitro differentiation ability was assessed by PCR and histological analysis.

RESULTS

The deposition of proteoglycans and type II collagen were maintained in loose fragments. However, loose fragment-derived chondrocytes had lower proliferating activity than condyle-derived fibrochondrocytes. Chondrogenic redifferentiation ability was lower in loose fragment chondrocytes than in condyle fibrochondrocytes. Differentiation towards adipogenic and osteogenic lineages was not observed in loose fragment chondrocytes. On the other hand, lipid vacuoles were detected in fibrochondrocytes after adipogenic treatment.

CONCLUSIONS

This study demonstrated that loose fragment-derived chondrocytes in SONK had lower potential than fibrochondrocytes in cellular proliferation and redifferentiation. Our experimental results suggest that osteonecrotic loose fragments might have restricted cellular properties in the healing of SONK-related osteochondral defects.

In vitro and in vivo modulation of cartilage degradation by a standardized Centella asiatica fraction

Osteoarthritis (OA) is a degenerative joint disease in which focal cartilage destruction is one of the primary features. The present study aims to evaluate the effect of a Centella asiatica fraction on in vitro and in vivo cartilage degradation. Bovine cartilage explants and bovine chondrocytes cultured in alginate were stimulated with IL-1 beta in the presence or absence of different concentrations (2, 5 and 10 microg/ml) of a standardized Centella asiatica triterpenes (CAT) fraction. The CAT fraction inhibited the IL-1 beta-induced proteoglycan (PG) release and nitric oxide (NO) production by cartilage explants in a dose-dependent manner. The IL-1 beta-induced reduction in PG synthesis and proliferation of chondrocytes cultured in alginate were counteracted by the CAT fraction at a concentration of 10 microg/ml. In a zymosan-induced acute arthritis model, the CAT fraction inhibited PG depletion without modulating joint swelling and inflammatory cell infiltration. In conclusion, the present study demonstrated for the first time that the tested Centella asiatica fraction was able to inhibit the zymosan-induced cartilage degradation in vivo without affecting the zymosan-induced inflammatory cell infiltration and joint swelling. The in vitro data indicate that the cartilage protective activity might at least partially be induced by the inhibition of NO production. The overall results indicate a possible disease modifying osteoarthritic activity of the Centella asiatica fraction.

Histologic evaluation of osteochondral loose bodies and repaired tissues after fixation

PURPOSE

The purpose of this study was to evaluate histologic changes in osteochondral loose bodies in the rabbit knee joint and histologic changes in repaired tissue after fixation of osteochondral loose bodies following isolation periods of varying length.

METHODS

We harvested osteochondral fragments from the patellar groove in rabbit knee joints and left them in the lateral gutters of the joints for periods of varying duration to create osteochondral loose bodies. We then evaluated histologic and immunohistochemical changes within these loose bodies. Next, we fixed osteochondral loose bodies that had been isolated for various periods within the joints to the osteochondral defect in the patellar groove. Twelve weeks after fixation, repaired tissues were evaluated histologically and immunohistochemically, and results were analyzed according to the varying isolation periods of fragments.

RESULTS

Extracellular matrix and type II collagen expression of osteochondral loose bodies deteriorated with increased duration of fragment isolation periods. A significantly negative correlation was noted between length of isolation periods and histologic grading scores. After osteochondral loose bodies had been fixed, repaired tissues deteriorated significantly in accordance with duration of fragment isolation periods. However, in some cases, even when osteochondral fragments had been isolated for 12 weeks, repaired tissues showed dense extracellular matrix stained by safranin O and abundant type II collagen expression, which indicated regeneration of the cartilage layer.

CONCLUSIONS

Osteochondral loose bodies and repaired tissues deteriorated after they were fixed to osteochondral defects. Although a direct correlation was noted between isolation periods of fragments and time to their deterioration, some osteochondral loose bodies showed regeneration of cartilage after fixation.

CLINICAL RELEVANCE

Clinically, reduction of osteochondral loose bodies should be performed as early as possible, if these can be found. However, even if the fragment seems to be old, fragment fixation is worthy of consideration.

IL-17, IL-1beta and TNF-alpha stimulate VEGF production by dedifferentiated chondrocytes

OBJECTIVE

To verify the involvement of proinflammatory cytokines IL-17, IL-1beta and tumor necrosis factor alpha (TNF-alpha) in cartilage vascularization by stimulating the production of vascular endothelial growth factor (VEGF) by chondrocytes isolated from patients with osteoarthritis (OA), in comparison with patients with rheumatoid arthritis (RA) and patients with femoral or humeral neck fracture (FP).

DESIGN

Chondrocytes isolated from patients with OA were maintained in monolayer culture for several passages. Chondrocyte dedifferentiation was monitored by the synthesis of cathepsin B by these cells. Chondrocytes freshly isolated at each subculture (subcultures 1-3) were stimulated with IL-17, IL-1beta or TNF-alpha. Supernatants were collected, immunoassayed for the production of VEGF and cathepsin B and assayed as the source of VEGF on the VEGF sensible ECV304 cell line. The cells were used to quantify intracellular cathepsin B enzymatic activity.

RESULTS

In differentiated conditions IL-1beta and TNF-alpha, but not IL-17, can inhibit the spontaneous secretion of VEGF by human OA, RA and FP chondrocytes, and IL-17 can restore the decrease in VEGF secretion caused by TNF-alpha. IL-17, together with IL-1beta and TNF-alpha, can enhance VEGF secretion to various extents by dedifferentiated OA chondrocytes. This change in effect with respect to primary culture was observable for all cytokines at the beginning of dedifferentiation, when the production of VEGF by chondrocytes had dramatically fallen and the cathepsin B synthesis had increased. The amount of VEGF induced by cytokines on dedifferentiated chondrocytes never reached the amount of VEGF produced by differentiated chondrocytes. VEGF produced by chondrocytes stimulated the ECV304 cell line proliferation.

CONCLUSIONS

These results indicate that dedifferentiated OA chondrocytes secrete VEGF after stimulation with proinflammatory cytokines. This event may be responsible for neovascularization found in OA cartilage.

Observations on the growth of loose bodies in joints

The categorization, origin, natural history, and histopathology of loose bodies in joints are well described in the literature. Clinical and basic science data have indirectly concluded that loose bodies grow over time; however, to date, there is no clearly documented published clinical example. This case report demonstrates the dramatic enlargement of 2 osteochondral loose bodies in a patient's knee over the course of a decade. The loose bodies possess a large number of viable cells; and growth appears to have occurred through encapsulation of the niduses by multiple layers of fibrocartilagenous tissue, thus confirming the findings of earlier studies.

In vitro characterization of chondrocytes isolated from naturally occurring osteochondrosis lesions of the humeral head of dogs

OBJECTIVE

To characterize chondrocytes from naturally occurring osteochondrosis (OC) lesions of the humeral head of dogs.

SAMPLE POPULATION

15 cartilage specimens from 13 client-owned dogs with humeral head OC and 10 specimens from the humeral head of healthy dogs (controls).

PROCEDURE

Chondrocytes were isolated and cultured in a 3-dimensional system. On days 7, 10, 15, 20, and 25, glycosaminoglycan and hydroxyproline content and cytologic characteristics were evaluated. Expression of collagen types I, II, and X was assessed by use of immunohistochemistry.

RESULTS

Chondrocytes from OC lesions were less viable, compared with control chondrocytes. Glycosaminoglycan content in the OC group was significantly less than in the control group on all days except day 20. Hydroxyproline content was also significantly less in the OC group on days 10, 20, and 25. Expression of collagen type II was significantly less in the OC group, compared with the control group on all days, whereas expression of collagen type I was significantly greater in the OC group on days 20 and 25. Expression of collagen type X was significantly less in the OC group on all days except day 25.

CONCLUSIONS AND CLINICAL RELEVANCE

Chondrocytes from naturally occurring OC lesions of the humeral head of dogs cultured in a 3-dimensional system were less viable and less capable of producing appropriate extracellular matrix molecules than chondrocytes from unaffected dogs. Alterations in the synthetic capabilities of chondrocytes from OC-affected cartilage may be a cause or an effect of the disease process.

Bone morphogenetic proteins promote cartilage differentiation and protect engineered artificial cartilage from fibroblast invasion and destruction

OBJECTIVE

An important role in joint and cartilage homeostasis in adults has been demonstrated recently for morphogenetic factors of the transforming growth factor beta family. Therefore, this study was undertaken to investigate the potential of bone morphogenetic proteins (BMPs) in chondrocyte differentiation using current technologies of tissue engineering.

METHODS

Complementary DNAs of recombinant human BMPs 2, 4, 5, 6, and 7 were transfected into primary bovine articular chondrocytes. Transgenic chondrocytes were assembled 3-dimensionally in alginate or in bioresorbable co-polymer fleeces of vicryl and polydioxanon embedded in low-melting-point agarose. Redifferentiation and formation of cartilage tissue in vitro or after subcutaneous transplantation into nude mice were assayed by semiquantitative reverse transcriptase-polymerase chain reaction, histology, and in situ hybridization, and findings were compared with those in unmodified or control-transfected primary chondrocytes.

RESULTS

Compared with other BMPs and control vector, BMP-7 induced a decrease in type I collagen expression in artificial cartilage, while transcription of the cartilage-specific type II collagen remained stable. In transplantation experiments, BMP-7 transgenic cartilage revealed the greatest amount of matrix synthesis, and BMP-7 was the only morphogen to suppress the infiltrative response of mouse fibroblastic cells into engineered cartilage, thereby preventing transplant destruction.

CONCLUSION

Cartilage differentiation and matrix maturation are promoted by BMPs in cartilage engineering. The inhibitory effect of BMP-7 on a nonspecific infiltrative response in immunocompromised nude mice further suggests that individual morphogens not only may contribute to cartilage maturation, but also may protect it from nonspecific inflammation and invasive destruction. These properties advance BMPs as promising tools for engineering of cartilaginous joint bioprostheses and as candidate biologic agents or genes for cartilage stabilization in arthritis.