Functional Recovery in Osteoarthritic Chondrocytes Through Hyaluronic Acid and Platelet-Rich Plasma-Inhibited Infrapatellar Fat Pad Adipocytes

Advances in the Treatment of Partial-Thickness Cartilage Defect

Partial-thickness cartilage defects (PTCDs) of the articular surface is the most common problem in cartilage degeneration, and also one of the main pathogenesis of osteoarthritis (OA). Due to the lack of a clear diagnosis, the symptoms are often more severe when full-thickness cartilage defect (FTCDs) is present. In contrast to FTCDs and osteochondral defects (OCDs), PTCDs does not injure the subchondral bone, there is no blood supply and bone marrow exudation, and the nearby microenvironment is unsuitable for stem cells adhesion, which completely loses the ability of self-repair. Some clinical studies have shown that partial-thickness cartilage defects is as harmful as full-thickness cartilage defects. Due to the poor effect of conservative treatment, the destructive surgical treatment is not suitable for the treatment of partial-thickness cartilage defects, and the current tissue engineering strategies are not effective, so it is urgent to develop novel strategies or treatment methods to repair PTCDs. In recent years, with the interdisciplinary development of bioscience, mechanics, material science and engineering, many discoveries have been made in the repair of PTCDs. This article reviews the current status and research progress in the treatment of PTCDs from the aspects of diagnosis and modeling of PTCDs, drug therapy, tissue transplantation repair technology and tissue engineering ("bottom-up").

Efficacy of a Novel Intra-Articular Administration of Platelet-Rich Plasma One-Week Prior to Hyaluronic Acid versus Platelet-Rich Plasma Alone in Knee Osteoarthritis: A Prospective, Randomized, Double-Blind, Controlled Trial

Recent studies have suggested that the combined injection of platelet-rich plasma (PRP) and hyaluronic acid (HA) may have additive benefits for knee osteoarthritis over PRP alone, but there is insufficient evidence to support this combined injection. Moreover, the simultaneous injection of PRP and HA may offset the combined effect. Hence, the aim of this prospective, randomized, double-blind study was to assess their combined efficacy with a novel injection protocol. Forty-six study subjects with unilateral knee osteoarthritis were randomized to receive either a single-dose injection of HA (intervention group) or normal saline (control group) 1 week after a single-dose injection of leukocyte-poor PRP. The Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) and static balance and the risk of falls measured by Biodex Balance System were, respectively, the primary and secondary outcome measures. Evaluations were performed at baseline, 1 month, 3 months, 6 months, and 12 months post-injection. The intervention group exhibited significant declines in WOMAC pain, stiffness, and total scores, as well as static balance, compared to the control group (p < 0.05). These randomized double-blind control trials, with novel protocol of intra-articular injection of PRP 1-week prior to HA, provide greater symptom relief and improve static balance compared to PRP alone in patients with knee osteoarthritis.

The long-term analgesic effectiveness of platelet-rich plasma injection for carpal tunnel syndrome: a cross-sectional cohort study

OBJECTIVE

Interest in perineural platelet-rich-plasma (PRP) injections for the treatment of carpal tunnel syndrome (CTS) has increased in recent years. However, evidence supporting the long-term effectiveness of PRP is lacking. Therefore, the aim of our cross-sectional cohort study was to investigate the long-term results of PRP injections for CTS.

METHODS

Eighty-one patients diagnosed with CTS of any grade who received a single PRP injection at least 2 years prior were enrolled. Through structured telephone interviews, all patients were asked of their post-injection outcomes compared to their pre-injection condition. Symptom relief ≥50%, compared to the pre-injection condition, was considered an effective outcome. Binary logistic regression was applied to analyze each baseline variable as a regressor for determining the prognostic outcome factors.

RESULTS

In total, 70% of patients reported positive outcomes ≥2 years post-injection. Shorter duration of symptoms before treatment (odds ratio: 0.991; 95% confidence interval [CI] 0.983-0.999; p = 0.023) and lower electrodiagnostic severity of CTS were the main prognostic factors for an effective outcome (mild grade vs. severe grade, odds ratio: 17.652; 95% CI 1.43-221.1; p = 0.025). Although there was a trend toward positive outcomes at longer follow-up durations (2-3 years vs. 3-4 years vs. 4-5 years), the difference was not statistically significant.

CONCLUSION

A single perineural PRP injection has a long-term analgesic effect on CTS, especially in mild-to-moderate cases.

PRP Injections for the Treatment of Knee Osteoarthritis: A Meta-Analysis of Randomized Controlled Trials

OBJECTIVE

To evaluate effectiveness, in terms of patient-reported outcome measures, of platelet-rich plasma (PRP) injections for knee osteoarthritis compared to placebo and other intraarticular treatments.

DESIGN

PubMed, Cochrane Library, Scopus, Embase, Web of Science, as well as the gray literature were searched on January 17, 2020. Randomized controlled trials (RCTs) comparing PRP injections with placebo or other injectable treatments, in any language, on humans, were included. Risk of bias was assessed following the Cochrane guidelines; quality of evidence was graded using the GRADE guidelines.

RESULTS

Thirty-four RCTs, including 1403 knees in PRP groups and 1426 in control groups, were selected. WOMAC (Western Ontario and McMaster Universities Osteoarthritis Index) score favored PRP, with a statistically and clinically significant difference versus placebo at 12-month follow-up (P = 0.02) and versus HA (hyaluronic acid) at 6-month (P < 0.001) and 12-month (P < 0.001) follow-ups. A clinically significant difference favoring PRP versus steroids was documented for VAS (Visual Analogue Scale) pain (P < 0.001), KOOS (Knee Injury and Osteoarthritis Outcome Score) pain (P < 0.001), function in daily activities (P = 0.001), and quality of life (P < 0.001) at 6-month follow-up. However, superiority of PRP did not reach the minimal clinically important difference for all outcomes, and quality of evidence was low.

CONCLUSIONS

The effect of platelet concentrates goes beyond its mere placebo effect, and PRP injections provide better results than other injectable options. This benefit increases over time, being not significant at earlier follow-ups but becoming clinically significant after 6 to 12 months. However, although substantial, the improvement remains partial and supported by low level of evidence. This finding urges further research to confirm benefits and identify the best formulation and indications for PRP injections in knee OA.

Platelet-Derived Biomaterials Inhibit Nicotine-Induced Intervertebral Disc Degeneration Through Regulating IGF-1/AKT/IRS-1 Signaling Axis

Apart from aging process, adult intervertebral disc (IVD) undergoes various degenerative processes. However, the nicotine has not been well identified as a contributing etiology. According to a few studies, nicotine ingestion through smoking, air or clothing may significantly accumulate in active as well as passive smokers. Since nicotine has been demonstrated to adversely impact various physiological processes, such as sympathetic nervous system, leading to impaired vasculature and cellular apoptosis, we aimed to investigate whether nicotine could induce IVD degeneration. In particular, we evaluated dose-dependent impact of nicotine in vitro to simulate its chronic accumulation, which was later treated by platelet-derived biomaterials (PDB). Further, during in vivo studies, mice were subcutaneously administered with nicotine to examine IVD-associated pathologic changes. The results revealed that nicotine could significantly reduce chondrocytes and chondrogenic indicators (Sox, Col II and aggrecan). Mice with nicotine treatment also exhibited malformed IVD structure with decreased Col II as well as proteoglycans, which was significantly increased after PDB administration for 4 weeks. Mechanistically, PDB significantly restored the levels of IGF-1 signaling proteins, particularly pIGF-1 R, pAKT, and IRS-1, modulating ECM synthesis by chondrocytes. Conclusively, the PDB impart reparative and tissue regenerative processes by inhibiting nicotine-initiated IVD degeneration, through regulating IGF-1/AKT/IRS-1 signaling axis.

Osteoarthritic infrapatellar fat pad aggravates cartilage degradation via activation of p38MAPK and ERK1/2 pathways

OBJECTIVE

This study aimed to investigate the biochemical effects of osteoarthritic infrapatellar fat pad (IPFP) on cartilage and the underlying mechanisms.

METHODS

Human IPFP and articular cartilage were collected from end-stage osteoarthritis (OA) patients during total knee arthroplasty. IPFP-derived fat-conditioned medium (FCM) was used to stimulate human primary chondrocytes and cartilage explants. Functional effect of osteoarthritic IPFP was explored in human primary chondrocytes and articular cartilage in vitro and ex vivo. Activation of relative pathways and its effects on chondrocytes were assessed through immunoblotting and inhibition experiments, respectively. Neutralization test was performed to identify the main factors and their associated pathways responsible for the effects of IPFP.

RESULTS

Osteoarthritic IPFP-derived FCM significantly induced extracellular matrix (ECM) degradation in both human primary chondrocytes and cartilage explants. Several pathways, such as NF-κB, mTORC1, p38MAPK, JNK, and ERK1/2 signaling, were significantly activated in human chondrocytes with osteoarthritic IPFP-derived FCM stimulation. Interestingly, inhibition of p38MAPK and ERK1/2 signaling pathway could alleviate the detrimental effects of FCM on chondrocytes, while inhibition of other signaling pathways had no similar results. In addition, IL-1β and TNF-α instead of IL-6 in osteoarthritic IPFP-derived FCM played key roles in cartilage degradation via activating p38MAPK rather than ERK1/2 signaling pathway.

CONCLUSION

Osteoarthritic IPFP induces the degradation and inflammation of cartilage via activation of p38MAPK and ERK1/2 pathways, in which IL-1β and TNF-α act as the key factors. Our study suggests that modulating the effects of IPFP on cartilage may be a promising strategy for knee OA intervention.

Amelioration of Nicotine-Induced Osteoarthritis by Platelet-Derived Biomaterials Through Modulating IGF-1/AKT/IRS-1 Signaling Axis

Besides inhalation, a few studies have indicated that the uptake of nicotine through air or clothing may be a significant pathway of its exposure among passive smokers. Nicotine is well known to exert various physiological impacts, including stimulating sympathetic nervous system, causing vascular disturbances, and inducing cell death. Therefore, we aimed to establish whether exposure of nicotine could induce articular cartilage degeneration in a mouse model of osteoarthritis (OA). We specifically assessed dose-dependent effect of nicotine in vitro to mimic its accumulation. Further, during the in vivo studies, mice subcutaneously administered with nicotine was examined for OA-associated pathologic changes. We found that nicotine significantly suppressed chondrocytes and chondrogenic markers (Sox, Col II, and aggrecan). Nicotine-treated mice also showed altered knee joint ultrastructure with reduced Col II and proteoglycans. After corroborating nicotine-induced OA characteristics, we treated this pathologic condition through employing platelet-derived biomaterial (PDB)-based regenerative therapy. The PDB significantly suppressed OA-like pathophysiological characteristics by 4 weeks. The mechanistic insight underlying this therapy demonstrated that PDB significantly restored levels of insulin-like growth factor 1 (IGF-1) signaling pathway proteins, especially pIGF-1 R, pAKT, and IRS-1, regulating extracellular matrix synthesis by chondrocytes. Taken together, the PDB exerts regenerative and reparative activities in nicotine-mediated initiation and progression of OA, through modulating IGF-1/AKT/IRS-1 signaling axis.

The Effect of Platelet-Rich Plasma on the Intra-Articular Microenvironment in Knee Osteoarthritis

Knee osteoarthritis (KOA) represents a clinical challenge due to poor potential for spontaneous healing of cartilage lesions. Several treatment options are available for KOA, including oral nonsteroidal anti-inflammatory drugs, physical therapy, braces, activity modification, and finally operative treatment. Intra-articular (IA) injections are usually used when the non-operative treatment is not effective, and when the surgery is not yet indicated. More and more studies suggesting that IA injections are as or even more efficient and safe than NSAIDs. Recently, research to improve intra-articular homeostasis has focused on biologic adjuncts, such as platelet-rich plasma (PRP). The catabolic and inflammatory intra-articular processes that exists in knee osteoarthritis (KOA) may be influenced by the administration of PRP and its derivatives. PRP can induce a regenerative response and lead to the improvement of metabolic functions of damaged structures. However, the positive effect on chondrogenesis and proliferation of mesenchymal stem cells (MSC) is still highly controversial. Recommendations from in vitro and animal research often lead to different clinical outcomes because it is difficult to translate non-clinical study outcomes and methodology recommendations to human clinical treatment protocols. In recent years, significant progress has been made in understanding the mechanism of PRP action. In this review, we will discuss mechanisms related to inflammation and chondrogenesis in cartilage repair and regenerative processes after PRP administration in in vitro and animal studies. Furthermore, we review clinical trials of PRP efficiency in changing the OA biomarkers in knee joint.

One-Year Efficacy of Platelet-Rich Plasma for Moderate-to-Severe Carpal Tunnel Syndrome: A Prospective, Randomized, Double-Blind, Controlled Trial

OBJECTIVE

To assess the therapeutic effect of platelet-rich plasma (PRP) for moderate-to-severe carpal tunnel syndrome (CTS).

DESIGN

A prospective, randomized, double-blinded, controlled trial (1-year follow-up).

SETTING

Outpatient of local medical center settings.

PARTICIPANTS

Patients (N=26) who were diagnosed with bilateral moderate-to-severe CTS (total 52 wrists) were included. For each patient, one wrist was randomized into either the PRP or control group and the contralateral wrist of the same patient was allocated to another group. Twenty-four patients were included in the final data analysis.

INTERVENTIONS

The wrists in the PRP group received a single ultrasound-guided dose of PRP injection (3.5mL), and the control group received a single ultrasound-guided injection with normal saline (3.5mL).

MAIN OUTCOME MEASURES

The Boston Carpal Tunnel Syndrome Questionnaire (BCTQ) scores were used as the primary outcome. Secondary outcomes encompassed the cross-sectional area of the median nerve and electrophysiological study. Assessments were conducted prior to injection and 1, 3, 6, and 12 months postinjection.

RESULTS

Compared to the control group, the PRP group exhibited significant improvements in BCTQ severity scores at all time points, BCTQ functional scores at the sixth month, and cross-sectional area at the 12th month postinjection (P<.0125).

CONCLUSIONS

A single dose of ultrasound-guided perineural PRP injection can provide therapeutic effect for 1 year postinjection.

The clinical efficacy of arthroscopic therapy with knee infrapatellar fat pad cell concentrates in treating knee cartilage lesion: a prospective, randomized, and controlled study

Introduction

To evaluate the clinical efficacy of arthroscopic therapy with infrapatellar fat pad cell concentrates in treating knee cartilage lesions, we conducted a prospective randomized single-blind clinical study of controlled method.

Methods

Sixty cases from Shanghai Changzheng Hospital from April 2018 to December 2019 were chosen and randomly divided into 2 groups equally. Patients in the experiment group were treated through knee arthroscopy with knee infrapatellar fat pad cell concentrates containing mesenchymal stromal cells, while patients in the control group were treated through regular knee arthroscopic therapy. VAS and WOMAC scores were assessed at pre-operation, and 6 weeks, 12 weeks, 6 months, and 12 months after intervention. MORCART scores were assessed at pre-operation and 12 months after intervention.

Results

Twenty-nine cases in the experiment group and 28 cases in the control group were followed up. No significant difference in VAS, WOMAC, and MOCART scores were found between the two groups before surgery (P > 0.05). The WOMAC total and WOMAC function scores of the experiment group were significantly lower than those of the control group 6 months and 12 months after surgery (P < 0.05). The VAS rest and VAS motion scores of the experiment group were found significantly lower than those of the control group 12 months after surgery (P < 0.05). The MOCART scores of the experiment group were found significantly higher compared with the control group 12 months after surgery (P < 0.05). No significant difference in WOMAC stiffness scores were found between the two groups.

Conclusions

The short-term results of our study are encouraging and demonstrate that knee arthroscopy with infrapatellar fat pad cell concentrates containing mesenchymal stromal cells is safe and provides assistance in reducing pain and improving function in patients with knee cartilage lesions.

Trial registration

ChiCTR1800015379. Registered on 27 March 2018, http://www.chictr.org.cn/showproj.aspx?proj=25901.

Pathological calcification in osteoarthritis: an outcome or a disease initiator?

In the progression of osteoarthritis, pathological calcification in the affected joint is an important feature. The role of these crystallites in the pathogenesis and progression of osteoarthritis is controversial; it remains unclear whether they act as a disease initiator or are present as a result of joint damage. Recent studies reported that the molecular mechanisms regulating physiological calcification of skeletal tissues are similar to those regulating pathological or ectopic calcification of soft tissues. Pathological calcification takes place when the equilibrium is disrupted. Calcium phosphate crystallites are identified in most affected joints and the presence of these crystallites is closely correlated with the extent of joint destruction. These observations suggest that pathological calcification is most likely to be a disease initiator instead of an outcome of osteoarthritis progression. Inhibiting pathological crystallite deposition within joint tissues therefore represents a potential therapeutic target in the management of osteoarthritis.

Sodium Hyaluronate and Platelet-Rich Plasma for Partial-Thickness Rotator Cuff Tears

Purpose

The treatment of partial-thickness rotator cuff tears (PTRCT) remains controversial. Few studies have focused on the conservative and new measurements of small to medium PTRCT. The use of sodium hyaluronate (SH) or platelet-rich plasma (PRP) as a method for rotator cuff repair requires further investigation. The aim of this study was to evaluate the combined use of SH and PRP in the treatment of small to medium PTRCT.

Study Design

A double-blinded randomized trial was used in this study.

Methods

Individuals with PTRCT detected by clinical examination and magnetic resonance imaging (MRI) were included in this study. The patients were randomly assigned to receive subacromial injections of normal saline, SH, PRP, or SH + PRP once a week for 4 wk. The primary outcome measure was the Constant score, and the secondary outcomes included the American Shoulder and Elbow Surgeons (ASES) and the visual analog scale scores. All of the clinical outcomes were assessed at pretreatment and 1, 3, 6, and 12 months posttreatment. MRI was used to evaluate the evolution of the cuff defect after 1 yr.

Results

The PRP group and the SH + PRP group showed a significantly higher Constant score and ASES score after the treatments. There were significant differences between the SH + PRP group and the SH or PRP group at 12 months in the Constant, visual analog scale, and ASES scores. MRI results showed that the tear size significantly decreased in both the PRP and the SH + PRP groups, especially in the SH + PRP group.

Conclusion

Our study provided evidence of the efficacy of PRP injection in the healing of small to medium PTRCT. Moreover, the combined injection of SH and PRP yielded a better clinical outcome than SH or PRP alone.

Biologic Therapies for the Treatment of Knee Osteoarthritis

BACKGROUND

The use of biologic therapies for the management of knee osteoarthritis has increased, despite insufficient evidence of efficacy. Our aim was to complete a systematic review and analysis of reports utilizing the highest level-of-evidence evaluating: (1) platelet-rich plasma injections (PRPs); (2) bone marrow-derived mesenchymal stem cells (BMSCs); (3) adipose-derived mesenchymal stem cells (ADSCs); and (4) amnion-derived mesenchymal stem cells (AMSCs).

METHODS

PubMed, Embase, and Cochrane Library databases were queried for studies evaluating PRP injections, BMSCs, ADSCs, and AMSCs in patients with knee osteoarthritis. Of 1009 studies identified within the last 5 years, 123 met inclusion criteria. A comprehensive analysis of all levels-of-evidence was performed, as well as separate analysis on level-of-evidence I studies. Level-of-evidence was determined by the American Academy of Orthopedic Surgeons classification system.

RESULTS

Although the majority of PRP reports demonstrated improvements in pain and/or function, others revealed no substantial improvements. Similar findings were noted for BMSCs, ADSCs, and AMSCs. Assessments of BMSC studies yielded majority with positive clinical results, although short-lived. Studies on ADSCs revealed improved clinical outcomes, but equivocal radiographic outcomes. Studies evaluating AMSCs demonstrated improvements in pain and function, and decreased radiographic evidence of osteoarthritis.

CONCLUSION

Despite some promising early results for PRP, BMSC, ADSC, and AMSC therapies, the majority of level-of-evidence I studies have multiple problems: small sample sizes, potentially inappropriate control cohorts, short-term follow-up, and so on. Despite the limitations, there still appears to be evidence justifying their use for knee osteoarthritis management. More high-level, larger human studies utilizing standardized protocols are needed.

Improvising PRP for use in osteoarthritis knee- upcoming trends and futuristic view

Platelet rich plasma (PRP) has clearly emerged offering a possible solution that could modify the disease process and offer symptomatic relief in early osteoarthritis of knee. Great efforts are underway to improve PRP products for use in knee osteoarthritis (OA). Upcoming research is focused on the ideal PRP type, dose, frequency of injection and mode of injection. The combination of PRP with biocompatible carriers/scaffolds like gelatin hydrogel and chitosan appear to be promising based on early in vitro and animal studies. PRP in combination with hyaluronate has also emerged to have synergistic and additive effects. This article intends to review the recent trends and advancing ideas for improvising PRP for use in early knee OA treatment.

Mechanistic insight into hyaluronic acid and platelet-rich plasma-mediated anti-inflammatory and anti-apoptotic activities in osteoarthritic mice

Osteoarthritis (OA) poses a major clinical challenges owing to limited regenerative ability of diseased or traumatized chondrocytes in articular cartilage. Previous studies have determined the individual therapeutic efficacies of hyaluronic acid (HA) and platelet-rich plasma (PRP) on OA; however, the underlying mechanism is still lacking. Therefore, we investigated mechanistic approach of HA+PRP therapy on chondrocyte apoptosis in IL-1β+TNF-α (I+T) treated in vitro OA model, in addition to in vivo anterior cruciate ligament transection-OA mice model. MTT assay showed an enhanced chondrocyte proliferation and viability in HA+PRP-treated group, compared to I+T, I+T/HA, I+T/PRP, I+T/HA+PRP groups. Further, HA+PRP also significantly suppressed ROS, apoptotic cleaved caspase-3 and PARP, p53 and p21 and MMP-1; whereas, cell cycle modulatory proteins including p-ERK, cyclin B1, D1, and E2 were upregulated. The sub-G1 population and TUNEL assay confirmed the higher abundance of healthy chondrocytes in HA+PRP group. A significantly decreased ARS staining in HA+PRP group was also noted, indicating reduced cartilaginous matrix mineralization compared to other groups. Conclusively, compared to HA or PRP, the combined HA+PRP might be a promising therapy for articular cartilage regeneration in osteoarthritic pathology, possibly via augmented anti-inflammatory, anti-oxidative chondrocyte proliferation and inhibited MMP-1 activity and matrix calcification.

Intra-articular injections of fat-derived mesenchymal stem cells in knee osteoarthritis: are they recommended?

INTRODUCTION

Knee osteoarthritis (OA) is one of the preeminent musculoskeletal illnesses in the adult population.

AIM

To investigate the role of intra-articular injections of joint fat-derived mesenchymal stem cells (MSCs) in knee OA.

METHODS

A Cochrane Library and PubMed (MEDLINE) search related to the role of intra-articular injections of joint fat-derived MSCs in knee OA was analyzed.

RESULTS

Experimental and clinical studies on intra-articular injections of joint fat-derived MSCs have provided satisfactory results (pain relief) in the short term. However, the results of a systematic review are controversial (more consistent trials are required for conclusive analysis).

CONCLUSIONS

The insufficient information found on the role of intra-articular injections of fat-derived MSCs in knee OA leads me to conclude that the technique is not appropriate for the management of OA. Raising false expectations and hopes to patients with knee OA should be eluded.

Sustained Release of Transforming Growth Factor-β1 from Platelet-Rich Chondroitin Sulfate Glycosaminoglycan Gels

Activated platelet-rich plasma (PRP), also referred to as platelet-rich fibrin (PRF), has been used to augment numerous techniques of cartilage repair in the knee but does not always result in superior quality of repair tissue. One possible reason that PRF does not consistently result in excellent cartilage regeneration is the transiency of growth factor provision with PRF. The objective of this study was to compare the release of transforming growth factor (TGF)-β1 from PRF and from PRP combined with a novel chondroitin sulfate glycosaminoglycan (CS-GAG) gel. PRP was prepared from nine healthy dogs and split into two aliquots: one activated with bovine thrombin and calcium chloride (CaCl₂) to form PRF and the other aliquot was used to rehydrate a lyophilized CS-GAG gel. Both PRF and the CS-GAG gels were incubated in media for 13 days and media were collected, stored, and replaced every 48 hours and the concentration of TGF-β1 quantified in the media using an enzyme-linked immunosorbent assay. Concentrations of TGF-β1 in the media were up to three times greater with the CS-GAG gels and were significantly (p < 0.05) greater than with PRF on days 3, 5, 7, 9, and 13. Furthermore, TGF-β1 elution was still substantial at day 13 with the use of the CS-GAG gels. Additional in vitro work is warranted to characterize TGF-β1 elution from this CS-GAG gel with human PRP and to determine whether the use of these CS-GAG gels can augment cartilage repair in vivo.

Combating Osteoarthritis through Stem Cell Therapies by Rejuvenating Cartilage: A Review

Knee osteoarthritis (OA) is a chronic degenerative disorder which could be distinguished by erosion of articular cartilage, pain, stiffness, and crepitus. Not only aging-associated alterations but also the metabolic factors such as hyperglycemia, dyslipidemia, and obesity affect articular tissues and may initiate or exacerbate the OA. The poor self-healing ability of articular cartilage due to limited regeneration in chondrocytes further adversely affects the osteoarthritic microenvironment. Traditional and current surgical treatment procedures for OA are limited and incapable to reverse the damage of articular cartilage. To overcome these limitations, cell-based therapies are currently being employed to repair and regenerate the structure and function of articular tissues. These therapies not only depend upon source and type of stem cells but also on environmental conditions, growth factors, and chemical and mechanical stimuli. Recently, the pluripotent and various multipotent mesenchymal stem cells have been employed for OA therapy, due to their differentiation potential towards chondrogenic lineage. Additionally, the stem cells have also been supplemented with growth factors to achieve higher healing response in osteoarthritic cartilage. In this review, we summarized the current status of stem cell therapies in OA pathophysiology and also highlighted the potential areas of further research needed in regenerative medicine.

Hyaluronan in the experimental injury of the cartilage: biochemical action and protective effects

INTRODUCTION

Our knowledge of extracellular matrix (ECM) structure and function has increased enormously over the last decade or so. There is evidence demonstrating that ECM provides signals affecting cell adhesion, shape, migration, proliferation, survival, and differentiation. ECM presents many domains that become active after proteolytic cleavage. These active ECM fragments are called matrikines which play different roles; in particular, they may act as potent inflammatory mediators during cartilage injury.

FINDINGS

A major component of the ECM that undergoes dynamic regulation during cartilage damage and inflammation is the non-sulphated glycosaminoglycan (GAG) hyaluronan (HA). In this contest, HA is the most studied because of its different activity due to the different polymerization state. In vivo evidences have shown that low molecular weight HA exerts pro-inflammatory action, while high molecular weight HA possesses anti-inflammatory properties. Therefore, the beneficial HA effects on arthritis are not only limited to its viscosity and lubricant action on the joints, but it is especially due to a specific and effective anti-inflammatory activity. Several in vitro experimental investigations demonstrated that HA treatment may regulate different biochemical pathways involved during the cartilage damage. Emerging reports are suggesting that the ability to recognize receptors both for the HA degraded fragments, whether for the high-polymerized native HA involve interaction with integrins, toll-like receptors (TLRs), and the cluster determinant (CD44). The activation of these receptors induced by small HA fragments, via the nuclear factor kappa-light-chain enhancer of activated B cell (NF-kB) mediation, directly or other different pathways, produces the transcription of a large number of damaging intermediates that lead to cartilage erosion.

CONCLUSIONS

This review briefly summarizes a number of findings of the recent studies focused on the protective effects of HA, at the different polymerization states, on experimental arthritis in vitro both in animal and human cultured chondrocytes.