Role of peroxiredoxin 6 in the chondroprotective effects of microvesicles from human adipose tissue-derived mesenchymal stem cells

Background

Osteoarthritis (OA) is a joint disease characterized by cartilage degradation, low-grade synovitis and subchondral bone alterations. In the damaged joint, there is a progressive increase of oxidative stress leading to disruption of chondrocyte homeostasis. The modulation of oxidative stress could control the expression of inflammatory and catabolic mediators involved in OA. We have previously demonstrated that extracellular vesicles (EVs) present in the secretome of human mesenchymal stem cells from adipose tissue (AD-MSCs) exert anti-inflammatory and anti-catabolic effects in OA chondrocytes. In the current work, we have investigated whether AD-MSC EVs could regulate oxidative stress in OA chondrocytes as well as the possible contribution of peroxiredoxin 6 (Prdx6).

Methods

Microvesicles (MV) and exosomes (EX) were isolated from AD-MSC conditioned medium by differential centrifugation with size filtration. The size and concentration of EVs were determined by resistive pulse sensing. OA chondrocytes were isolated from knee articular cartilage of advanced OA patients. 4-Hydroxynonenal adducts, IL-6 and MMP-13 were determined by enzyme-linked immunosorbent assay. Expression of Prdx6 and autophagic markers was assessed by immunofluorescence and Western blotting. Prdx6 was downregulated in AD-MSCs by transfection with a specific siRNA.

Results

MV and to a lesser extent EX significantly reduced the production of oxidative stress in OA chondrocytes stimulated with IL-1β. Treatment with MV resulted in a dramatic upregulation of Prdx6. MV also enhanced the expression of autophagy marker LC3B. We downregulated Prdx6 in AD-MSCs by using a specific siRNA and then MV were isolated. These Prdx6-silenced MV failed to modify oxidative stress and the expression of autophagy markers. We also assessed the possible contribution of Prdx6 to the effects of MV on IL-6 and MMP-13 production. The reduction in the levels of both mediators induced by MV was partly reverted after Prdx6 silencing.

Conclusion

Our results indicate that EVs from AD-MSCs regulate the production of oxidative stress in OA chondrocytes during inflammation. Prdx6 may mediate the antioxidant and protective effects of MV.

The translational potential of this article: This study gives insight into the protective properties of EVs from AD-MSCs in OA chondrocytes. Our findings support the development of novel therapies based on EVs to prevent or treat cartilage degradation.

Knee Extensor Muscle Strength Is More Important Than Postural Balance for Stair-Climbing Ability in Elderly Patients with Severe Knee Osteoarthritis

Knee osteoarthritis is a chronic joint disease which damages articular cartilage. In its severe stages, it results in impairments in balance and muscle strength loss, which affect daily life activities such as walking or climbing stairs. This study sought to investigate associated factors with stair-climbing ability in this population, with special interest in measuring the relevance of postural balance for this task. Forty-four patients scheduled to undergo unilateral total knee arthroplasty were assessed. Timed up and go test, stair ascent–descent test, three different isometric strength tests (knee flexion, knee extension and hip abduction), active knee extension and flexion range of movement and static postural balance assessment were evaluated. Spearman’s correlation coefficients and multiple linear regression analysis determined the strength of association between the different variables and stair-climbing time. No significant association between the stair-climbing time and static balance was found. Significant associations were found between stair-climbing time and timed up and go (r = 0.71; p < 0.0001) and maximal knee extensor strength (r = –0.52; p = 0.0003). One-year increase in age was associated with 0.15 s (95% CI 0.00 to 0.30) slower stair-climbing time. In conclusion, muscle strength is more important than postural balance for stair-climbing ability in this population.

A randomized controlled trial assessing the effects of preoperative strengthening plus balance training on balance and functional outcome up to 1 year following total knee replacement

PURPOSE

To investigate the effects of including balance training in a preoperative strengthening intervention on balance and functional outcomes in patients undergoing total knee replacement (TKR) and compare these effects to those induced by preoperative strengthening and no intervention.

METHODS

Eighty-two subjects scheduled for TKR were randomly allocated into the strengthening (ST, n = 28) group: a preoperative lower limb strengthening intervention; the strengthening + balance (ST + B, n = 28) group: same intervention augmented with balance training; and the control group (n = 26). The Berg Balance Scale (BBS) and the function in daily living subscale of the Knee Injury and Osteoarthritis Outcome Score (KOOS-ADL) were the primary outcomes. The secondary measures included balance and mobility, self-reported status, and knee function. The outcomes were assessed at baseline, 1 week before surgery, and 2, (primary endpoint), 6 and 52 weeks after surgery.

RESULTS

Compared with the controls, the participants in the ST and ST + B groups presented significant improvements from baseline to the end of the preoperative intervention in BBS (p = 0.005) and KOOS-ADL (p < 0.001). At 6 weeks post-surgery, the knee extensor strength values were similar in the two treatment groups and significantly higher than that in the controls. Overall, the participant outcomes in all groups stabilized at 1 year after surgery.

CONCLUSION

A preoperative strengthening intervention, regardless of whether it is complemented with balance training, enhances strength but not balance or functional outcomes at 6 weeks after surgery. Patients are expected to present similar performance at 1 year postoperatively, but adequately statistically powered trials are needed to confirm the findings.

LEVEL OF EVIDENCE

II.

TRIAL REGISTRATION

NCT02995668.

Effects of balance and proprioceptive training on total hip and knee replacement rehabilitation: A systematic review and meta-analysis

BACKGOUND

Balance and proprioceptive deficits are frequently persistent after total joint replacement, limiting functionality and involving altered movement patterns and difficulties in walking and maintaining postural control among patients.

RESEARCH QUESTION

The goal of this systematic review was to evaluate the short- and mid-term effects of proprioceptive and balance training for patients undergoing total knee and hip replacement.

METHODS

This is a systematic review of literature. MEDLINE, Embase, Cochrane Library, PEDro, and Scopus were the databases searched. The review included randomized clinical trials in which the experimental groups underwent a training aimed at improving balance and proprioception, in addition to conventional care. The studies had to assess at least one of the following outcomes: self-reported functionality or balance (primary outcomes), knee function, pain, falls, or quality of life.

RESULTS

Eight trials were included, involving 567 participants. The quantitative synthesis found a moderate to high significant effect of balance and proprioceptive trainings on self-reported functionality and balance after total knee replacement. The effects were maintained at mid-term in terms of balance alone. Conversely, preoperative training did not enhance outcomes after total hip arthroplasty.

SIGNIFICANCE

The synthesis showed that, in clinical terms, balance trainings are a convenient complement to conventional physiotherapy care to produce an impact on balance and functionality after knee replacement. If outcomes such as improvement in pain, knee range of movement, or patient quality of life are to be promoted, it would be advisable to explore alternative proposals specifically targeting these goals. Further research is needed to confirm or discard the current evidence ultimately, predominantly in terms of the effects on the hips and those yielded by preoperative interventions.

Revision of infected total knee arthroplasty: two-stage reimplantation using an antibiotic-impregnated static spacer

BACKGROUND

A two-stage revision remains as the "gold standard" treatment for chronically infected total knee arthroplasties.

METHODS

Forty-five septic knee prostheses were revised with a minimum follow-up of 5 years. Static antibiotic-impregnated cement spacers were used in all cases. Intravenous antibiotics according to sensitivity test of the culture were applied during patients' hospital stay. Oral antibiotics were given for another 5 weeks. Second-stage surgery was undertaken after control of infection with normal erythrocyte sedimentation rate and C-reactive protein values. Extensile techniques were used if needed and metallic augments were employed for bone loss in 32 femoral and 29 tibial revisions.

RESULTS

The average interval between the first-stage resection and reimplantation was 4.4 months. Significant improvement was obtained with respect to visual analog scale pain and clinical and functional scores, and infection was eradicated in 95.6% of cases following a two-stage revision total knee arthroplasty. Radiographic evaluation showed suitable alignment without signs of mechanical loosening.

CONCLUSIONS

This technique is a reasonable procedure to eradicate chronic infection in knee arthroplasty and provides proper functional and clinical results. However, it sometimes requires extensile surgical approaches that could imply arduous surgeries. Metallic augments with cementless stems available in most of the knee revision systems are a suitable alternative to handle bone deficiencies, avoiding the use of bone allografts with its complications.