Potential of exogenous cartilage proteoglycan as a new material for cartilage regeneration

The efficacy and tolerability of proteoglycan F in the treatment of knee osteoarthritis: A prospective, randomized, double-blind controlled trial

Objective

To identify the efficacy and tolerability of Proteoglycan F in patients with primary knee OA.Design: A 24-week randomized, placebo-controlled, double-blind clinical trial with two arms: (1) Proteoglycan F (received 10 ​mg proteoglycan daily, for 24 weeks) and (2) control group (received placebo). Knee symptoms and joint cartilage status (evaluated by ultrasound and MRI of knee joints), quality of life, serum cytokine levels (IL-1β and TNF-α), and safety evaluation were measured before, during, and after the treatment.

Results

After 24-week treatment, pain reduction (in the KOOS pain score) of at least 20% and at least 50% (NRS scale) compared to baseline in the PGF group was significantly higher than those in the control group. The PGF group had greater reductions in the total scores of subchondral bone marrow edema, and bone cocoon under cartilage on knee MRI (classification according to WORMs), which were -2.27 (-4.0; -0.51) and -1.77 (-3.08; -0.46), respectively (p ​< ​0.05). The two groups had no statistically significant difference in knee ultrasound characteristics. After 4 weeks, 12, and 24 weeks compared to baseline, there was no statistically significant difference in levels of urea, creatinine, aspartate aminotransferase, and alanine aminotransferase within the group and between the two study groups.

Conclusions

Salmon cartilage PG with 10 ​mg per day has potential to improve pain symptoms and subchondral bone marrow edema and bone cocoon under cartilage lesions in primary knee OA. However, the efficacy of PGF should be viewed with caution, and future studies are needed for more specific evaluation.

Oral Administration of Salmon Cartilage Proteoglycan Attenuates Osteoarthritis in a Monosodium Iodoacetate-Induced Rat Model

Proteoglycan (PG) is a type of glycoprotein which forms an extracellular matrix with collagen and hyaluronic acid to maintain articular cartilage, synovial membrane, and synovial fluid. This study aimed to evaluate the antiosteoarthritis effects of salmon nasal cartilage-derived PG in alleviating knee osteoarthritis in an osteoarthritis rat model. Knee osteoarthritis was induced in rats by intra-articular injection of monosodium iodoacetate (MIA), 3 mg/knee, to the right knee. Animals were then administered either diclofenac (3 mg/kg body weight [b.w]/day) or proteoglycan F (PGF; 40 mg/kg and 120 mg/kg b.w/day) by oral gavage for 6 consecutive weeks. Knee diameters were measured throughout the experimental period; serum interleukin-1β and tumor necrosis factor-alpha (TNF-α) levels, and histological analysis of the ligament were carried out at the end of the experiment. Salmon cartilage PG considerably alleviated the osteoarthritis symptoms in the model and lowered the serum concentrations of interleukin-1β and TNF-α. Diclofenac 3 mg/kg/day and PGF at doses of 40 mg/kg/day and 120 mg/kg/day also improved articular cartilage structure on further histological studies. This study demonstrated the in vivo effect of salmon cartilage PG in attenuating symptoms in an MIA-induced rat model, including reduction of inflammatory markers and histological improvement of cartilage tissue.

Evaluation of the effect of salmon nasal proteoglycan on biomarkers for cartilage metabolism in individuals with knee joint discomfort: A randomized double-blind placebo-controlled clinical study

A randomized double-blind placebo-controlled clinical trial was conducted to evaluate the chondroprotective action of salmon nasal cartilage proteoglycan on joint health. The effect of oral administration of proteoglycan (10 mg/day) on cartilage metabolism was evaluated in individuals with knee joint discomfort but without diagnosis of knee osteoarthritis. The average age of patients was 52.6±1.1 years old. The effect of proteoglycan was evaluated by analyzing markers for type II collagen degradation (C1,2C) and synthesis (PIICP), and the ratio of type II collagen degradation to synthesis. The results indicated that the change in C1,2C levels significantly differed in the proteoglycan group compared with the placebo group following 16 weeks intervention among subjects with high levels of knee pain and physical dysfunction (total score of Japan Knee Osteoarthritis Measure ≥41) and subjects with constant knee pain (both P<0.05). There was a greater increase in PIICP levels in the proteoglycan group than the placebo group following intervention, although this difference was not significant in both sets of patients. Thus, the C1,2C/PIICP ratios decreased in the proteoglycan group, whereas they slightly increased in the placebo group following the intervention. Furthermore, no test supplement-related adverse events were observed during the intervention. Therefore, oral administration of salmon nasal cartilage proteoglycan at a dose of 10 mg/day may exert a chondroprotective action in subjects with knee joint discomfort. This effect was achieved by improving cartilage metabolism (reducing type II collagen degradation and enhancing type II collagen synthesis), without causing apparent adverse effects.

Chondroitin sulfate proteoglycans from salmon nasal cartilage inhibit angiogenesis

Because cartilage lacks nerves, blood vessels, and lymphatic vessels, it is thought to contain factors that inhibit the growth and development of those tissues. Chondroitin sulfate proteoglycans (CSPGs) are a major extracellular component in cartilage. CSPGs contribute to joint flexibility and regulate extracellular signaling via their attached glycosaminoglycan, chondroitin sulfate (CS). CS and CSPG inhibit axonal regeneration; however, their role in blood vessel formation is largely unknown. To clarify the function of CSPG in blood vessel formation, we tested salmon nasal cartilage proteoglycan (PG), a member of the aggrecan family of CSPG, for endothelial capillary-like tube formation. Treatment with salmon PG inhibited endothelial cell adhesion and in vitro tube formation. The anti-angiogenic activity was derived from CS in the salmon PG but not the core protein. Salmon PG also reduced matrix metalloproteinase expression and inhibited angiogenesis in the chick chorioallantoic membrane. All of these data support an anti-angiogenic role for CSPG in cartilage.

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The role of CSPGs in blood vessel formation in cartilage is largely unknown.

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Treatment of salmon PG inhibited in vitro and in vivo angiogenesis.

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The CS portion of salmon PG was responsible for the anti-angiogenic activity.

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Salmon PG also reduced MMP expression and inhibited cell adhesion.

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Our results support an anti-angiogenic role for CSPG in cartilage.

Bushen Zhuangjin Decoction promotes chondrocyte proliferation by stimulating cell cycle progression

Bushen Zhuangjin Decoction (BZD), a well-known formulation in Traditional Chinese Medicine, has been widely used for the treatment of osteoarthritis (OA). Due to the poor intrinsic repair capacity of chondrocytes, promoting the proliferation of chondrocytes is an efficient treatment to delay the progression of cartilage degradation. The present study, therefore, focused on the effect of BZD on chondrocyte proliferation, exploring the mechanism of BZD on the inhibition of cartilage degradation. Chondrocytes isolated from the knee articular cartilage of Sprague Dawley rats were cultured and identified by type II collagen immunohistochemistry. It was found that BZD promoted chondrocyte viability in a dose- and time-dependent manner. To investigate if BZD promoted the chondrocyte viability by stimulating the cell cycle progression a flow cytometer was used, and the results showed that the percentage proportion of G0/G1 cells was significantly lower, and the percentage proportion of S cells was significantly higher, in treated cells compared with that in untreated cells. To gain insight into the mechanism underlying the effect of BZD on the cell cycle progression, the mRNA and protein expression of cyclin D1, cyclin-dependent kinase 4 (CDK4), CDK6 and p21 was measured by reverse transcription-polymerase chain reaction and western blotting, respectively. The mRNA and protein expression of cyclin D1, CDK4 and CDK6 in the BZD-treated chondrocytes was significantly upregulated, while the mRNA and protein expression of p21 was significantly downregulated, compared with that in the untreated chondrocytes. These results suggested that BZD promoted chondrocyte proliferation by accelerating G1/S transition, indicating that BZD is a potential therapeutic agent for the treatment of OA.

Functionalization of dynamic culture surfaces with a cartilage extracellular matrix extract enhances chondrocyte phenotype against dedifferentiation

Culture on silicone rubber surfaces has been shown to partially overcome the chondrocyte dedifferentiation characteristic of standard culture on rigid polystyrene. These methods typically involve functionalization of culture surfaces with proteins. Collagen type I is often used, but more cartilage-specific proteins may be more appropriate for chondrocytes. To explore this hypothesis, a twofold experimental design was applied. First, chondrocytes were cultured in rigid Petri dishes coated with silicone rubber ("static silicone" or SS culture) functionalized with either cartilage extracellular matrix (ECM) extract or collagen type I. Second, chondrocytes were cultured on monotonically expanded high extension silicone rubber dishes ("continuous expansion" or CE culture) functionalized with ECM extract and compared to cells grown in SS culture. There were no differential effects of surface functionalization with the ECM extract vs. collagen type I on chondrocyte morphology, viability, proliferation or apoptosis in SS culture. However, chondrocyte growth on the ECM extract was associated with significantly reduced collagen types I and X gene expression and significantly increased glycosaminoglycan (GAG) secretion. After 3 passages (P3) on ECM-coated SS culture, chondrocyte phenotype and GAG secretion was enhanced compared to cells passaged on collagen type I. Pellet cultures from P3 SS culture displayed enhanced collagen type II content when ECM extract was used for functionalization rather than collagen type I. In CE culture with ECM functionalization, chondrocyte dedifferentiation was significantly inhibited vs. SS cultures, as evidenced by both gene expression and pellet cultures. Functionalization of extendable culture surfaces with cartilage ECM extract therefore supports enhanced preservation of chondrocyte phenotype.