Effects of hyaluronan on three-dimensional microarchitecture of subchondral bone tissues in guinea pig primary osteoarthrosis

A whole-joint histopathologic grading system for murine knee osteoarthritis

This study aims to develop a comprehensive and easily executable histopathologic grading scheme for murine knee osteoarthritis (OA) using specific scoring criteria for both cartilage and periarticular changes, which may overcome important limitations of the existing grading systems. The new grading scheme was developed based on mouse knee OA models with observation periods up to 24 months of age (spontaneous OA) or 24-week post-injury (posttraumatic OA). Semi-quantitative assessments of the histopathologic OA changes were applied to all four quadrants per femorotibial joint for 50 joints (200 quadrants) using specific scoring criteria rather than mild to severe grades. Scoring elements per quadrant were as follows: cartilage lesion (0-7), osteophyte (0-3), subchondral bone change (0-3), synovitis (0-3), and ectopic periarticular soft-tissue chondrogenesis and ossification (0-3). The new histopathologic grading scheme had high intra- and interobserver reproducibility (correlation coefficients r > 0.95) across experienced and novice observers. Sensitivity and reliability analyses confirmed the ability of the new scheme to detect minimal but significant OA progression (p < 0.01) within a 2-week interval and to accurately identify tissue- and quadrant-specific OA severity within the joints. In conclusion, this study presents the first whole-joint histopathologic grading scheme for murine knee OA that covers all-stage osteoarthritic changes in all major joint tissues, including periarticular soft-tissue ossification that is not included in any of the existing OA grading systems. This reproducible scheme is easy to execute and sensitive to minimal OA progression without using computer software, suitable for quick OA severity assessments of the entire femorotibial joint.

Adhesive hydrogels in osteoarthritis: from design to application

Osteoarthritis (OA) is the most common type of degenerative joint disease which affects 7% of the global population and more than 500 million people worldwide. One research frontier is the development of hydrogels for OA treatment, which operate either as functional scaffolds of tissue engineering or as delivery vehicles of functional additives. Both approaches address the big challenge: establishing stable integration of such delivery systems or implants. Adhesive hydrogels provide possible solutions to this challenge. However, few studies have described the current advances in using adhesive hydrogel for OA treatment. This review summarizes the commonly used hydrogels with their adhesion mechanisms and components. Additionally, recognizing that OA is a complex disease involving different biological mechanisms, the bioactive therapeutic strategies are also presented. By presenting the adhesive hydrogels in an interdisciplinary way, including both the fields of chemistry and biology, this review will attempt to provide a comprehensive insight for designing novel bioadhesive systems for OA therapy.

Quantifying the Human Subchondral Trabecular Bone Microstructure in Osteoarthritis with Clinical CT

Osteoarthritis (OA) is characterized by critical alterations of the subchondral bone microstructure, besides the well-known cartilaginous changes. Clinical computed tomography (CT) detection of quantitative 3D microstructural subchondral bone parameters is applied to monitor changes of subchondral bone structure in different stages of human OA and is compared with micro-CT, the gold standard. Determination by clinical CT (287 µm resolution) of key microstructural parameters in tibial plateaus with mild-to-moderate and severe OA reveals strong correlations to micro-CT (35 µm), high inter- and intraobserver reliability, and small relative differences. In vivo, normal, mild-to-moderate, and severe OA are compared with clinical CT (331 µm). All approaches detect characteristic expanded trabecular structure in severe OA and fundamental microstructural correlations with clinical OA stage. Multivariate analyses at various in vivo and ex vivo imaging resolutions always reliably separate mild-to-moderate from severe OA (except mild-to-moderate OA from normal), revealing a striking similarity between 287 µm clinical and 35 µm micro-CT. Thus, accurate structural measurements using clinical CT with a resolution near the trabecular dimensions are possible. Clinical CT offers an opportunity to quantitatively monitor subchondral bone microstructure in clinical and experimental settings as an advanced tool of investigating OA and other diseases affecting bone architecture.

Comparative anatomy and morphology of the knee in translational models for articular cartilage disorders. Part II: Small animals

BACKGROUND

Small animal models are critical to model the complex disease mechanisms affecting a functional joint leading to articular cartilage disorders. They are advantageous for several reasons and significantly contributed to the understanding of the mechanisms of cartilage diseases among which osteoarthritis.

METHODS

Literature search in Pubmed.

RESULTS AND DISCUSSION

This narrative review summarizes the most relevant anatomical structural and functional characteristics of the knee (stifle) joints of the major small animal species, including mice, rats, guinea pigs, and rabbits compared with humans. Specific characteristics of each species, including kinematical gait parameters are provided and compared with the human situation. When placed in a proper context respecting their challenges and limitations, small animal models are important and appropriate models for articular cartilage disorders.

Bone marrow lesions in knee osteoarthritis: regional differences in tibial subchondral bone microstructure and their association with cartilage degeneration

OBJECTIVE

The aim of this study was to investigate how bone microstructure within bone marrow lesions (BMLs) relates to the bone and cartilage across the whole human tibial plateau.

DESIGN

Thirty-two tibial plateaus from patients with osteoarthritis (OA) at total knee arthroplasty and eleven age-matched non-OA controls, were scanned ex vivo by MRI to identify BMLs and by micro CT to quantitate the subchondral (plate and trabecular) bone microstructure. For cartilage evaluation, specimens were processed histologically.

RESULTS

BMLs were detected in 75% of the OA samples (OA-BML), located predominantly in the anterior-medial (AM) region. In contrast to non-OA control and OA-no BML, in OA-BML differences in microstructure were significantly more evident between subregions. In OA-BML, the AM region contained the most prominent structural alterations. Between-group comparisons showed that the AM region of the OA-BML group had significantly higher histological degeneration (OARSI grade) (P < .0001, P < .05), thicker subchondral plate (P < .05, P < .05), trabeculae that are more anisotropic (P < .0001, P < .05), well connected (P < .05, P = n.s), and more plate-like (P < 0.05, P < 0.05), compared to controls and OA-no BML at this site. Compared to controls, OA-no BML had significantly higher OARSI grade (P < .0001), and lower trabecular number (P < .05).

CONCLUSION

In established knee OA, both the extent of cartilage damage and microstructural degeneration of the subchondral bone were dependent on the presence of a BML. In OA-no BML, bone microstructural alterations are consistent with a bone attrition phase of the disease. Thus, the use of BMLs as MRI image-based biomarkers appear to inform on the degenerative state within the osteochondral unit.

CCL25-Supplemented Hyaluronic Acid Attenuates Cartilage Degeneration in a Guinea Pig Model of Knee Osteoarthritis

There is evidence that the application of mesenchymal stromal cells (MSCs) counteracts osteoarthritis (OA) progression. However, the prospect of extracting and expanding these cells might be limited. The aim of this study was to investigate whether hyaluronic acid (HA) supplemented with MSC-recruiting chemokine C-C motif ligand 25 (CCL25) can influence the natural course of spontaneous OA in the guinea pig. CCL25 concentration in synovial fluid (SF) was quantified with enzyme-linked immunosorbent assay. Boyden chamber cell migration assay was used to test CCL25-mediated migration of guinea pig MSC. Forty-nine 11-month-old male guinea pigs were divided into seven groups. The main treatments consisted of five intra-articular injections of HA in pure form and in combination with three doses of CCL25 (63, 693, and 6,993 pg) given at a weekly interval. The severity of cartilage damage was assessed by using a modified Mankin score. The measured average physiological concentration of CCL25 in SF of animals is 85 ± 39 pg/ml. MSC showed a 3.2-fold increase in cell migration at 1,000 nM CCL25 in vitro demonstrating the biological migratory activity of CCL25 on these cells. In vivo, treatment with HA alone did not reduce OA progression. Similarly, OA scores were not found significantly reduced after treatment with 63 pg CCL25 + HA. However, when compared to pure HA, treatment with 693 pg CCL25 + HA and 6,993 pg CCL25 + HA significantly reduced the OA score from 10.1 to 7.4 (-28%) and 8.4 (-20%), respectively. These data suggest that intra-articular injections of HA supplemented with CCL25 attenuates OA. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 37:1723-1729, 2019.

Chitosan in viscosupplementation: in vivo effect on rabbit subchondral bone

Background

To investigate the effect of intra-articular injection of Chitosan (Cs) added to hyaluronic acid (HA) on subchondral bone during osteoarthritis (OA), microarchitectural parameters and mineral density were measured in a rabbit model of early OA. A novel hybrid hydrogel adding reacetylated Cs of fungal origin to HA was compared to high molecular weight HA commercial formulation.

Method

Eighteen rabbits underwent unilateral anterior cruciate ligament transection (ACLT) and were divided into three groups (Saline-group, HA-group and Hybrid-group) depending on the intra-articular injection compound. Eight contralateral knees were used as non-operated controls (Contralateral-group). Micro-computed tomography was performed six weeks post-ACLT to study subchondral bone microarchitectural parameters and mineral density at an early stage of OA development.

Results

Cartilage thickness mean value was reduced only in Saline-group compared to Contralateral-group. When the Hybrid-group was compared to Saline-group, subchondral bone microarchitectural parameters (trabecular thickness and trabecular bone volume fraction) were significantly changed; subchondral bone plate and trabecular bone mineral densities (bone mineral density and tissue mineral density) were reduced. When the Hybrid-group was compared to HA-group, subchondral bone microarchitectural parameters (subchondral plate thickness and trabecular thickness) and trabecular bone mineral densities (bone mineral density and tissue mineral density) were significantly decreased.

Conclusion

Conclusion: Compared to HA alone, the novel hybrid hydrogel, constituted of Cs added to HA, enhanced microarchitectural parameters and mineral density changes, leading to subchondral bone loss in a rabbit model of early experimental OA.

The mechanism of action for hyaluronic acid treatment in the osteoarthritic knee: a systematic review

BACKGROUND

Knee osteoarthritis (OA) is one of the leading causes of disability within the adult population. Current treatment options for OA of the knee include intra-articular (IA) hyaluronic acid (HA), a molecule found intrinsically within the knee joint that provides viscoelastic properties to the synovial fluid. A variety of mechanisms in which HA is thought to combat knee OA are reported in the current basic literature.

METHODS

We conducted a comprehensive literature search to identify currently available primary non-clinical basic science articles focussing on the mechanism of action of IA-HA treatment. Included articles were assessed and categorized based on the mechanism of action described within them. The key findings and conclusions from each included article were obtained and analyzed in aggregate with studies of the same categorical assignment.

RESULTS

Chondroprotection was the most frequent mechanism reported within the included articles, followed by proteoglycan and glycosaminoglycan synthesis, anti-inflammatory, mechanical, subchondral, and analgesic actions. HA-cluster of differentiation 44 (CD44) receptor binding was the most frequently reported biological cause of the mechanisms presented. High molecular weight HA was seen to be superior to lower molecular weight HA products. HA derived through a biological fermentation process is also described as having favorable safety outcomes over avian-derived HA products.

CONCLUSIONS

The non-clinical basic science literature provides evidence for numerous mechanisms in which HA acts on joint structures and function. These actions provide support for the purported clinical benefit of IA-HA in OA of the knee. Future research should not only focus on the pain relief provided by IA-HA treatment, but the disease modification properties that this treatment modality possesses as well.

Effects of P-15 Peptide Coated Hydroxyapatite on Tibial Defect Repair In Vivo in Normal and Osteoporotic Rats

This study assessed the efficacy of anorganic bone mineral coated with P-15 peptide (ABM/P-15) on tibia defect repair longitudinally in both normal and osteoporotic rats in vivo. A paired design was used. 24 Norwegian brown rats were divided into normal and osteoporotic groups. 48 cylindrical defects were created in proximal tibias bilaterally. Defects were filled with ABM/P-15 or left empty. Osteoporotic status was assessed by microarchitectural analysis. Microarchitectural properties of proximal tibial defects were evaluated at 4 time points. 21 days after surgery, tibias were harvested for histology and histomorphometry. Significantly increased bone volume fraction, surface density, and connectivity were seen in all groups at days 14 and 21 compared with day 0. Moreover, the structure type of ABM/P-15 group was changed toward typical plate-like structure. Microarchitectural properties of ABM/P-15 treated newly formed bones at 21 days were similar in normal and osteoporotic rats. Histologically, significant bone formation was seen in all groups. Interestingly, significantly increased bone formation was seen in osteoporotic rats treated with ABM/P-15 indicating optimized healing potential. Empty defects showed lower healing potential in osteoporotic bone. In conclusion, ABM/P-15 accelerated bone regeneration in osteoporotic rats but did not enhance bone regeneration in normal rats.

Efficacy study of two novel hyaluronic acid-based formulations for viscosupplementation therapy in an early osteoarthrosic rabbit model

Viscosupplementation (VS) is a therapy for osteoarthrosis (OA) consisting of repetitive intra-articular injections of hyaluronic acid (HA). It is known to be clinically effective in relieving pain and increasing joint mobility by restoring joint homeostasis. In this study, the effects of two novel HA-based VS hydrogel formulations were assessed and challenged against a pure HA commercial formulation for the first time and this in a rabbit model of early OA induced by anterior cruciate ligament transection (ACLT). The first formulation tested was a hybrid hydrogel composed of HA and reacetylated chitosan, a biopolymer considered to be chondroprotective, assembled thanks to an ionic shielding. The second formulation consisted of a novel HA polymer grafted with antioxidant molecules (HA-4AR) aiming at decreasing OA oxidative stress and increasing HA retention time in the articulation. ACLT was performed on rabbits in order to cause structural changes comparable to traumatic osteoarthrosis. The protective effects of the different formulations were observed on the early phase of the pathology in a full randomized and blinded manner. The cartilage, synovial membrane, and subchondral bone were evaluated by complementary investigation techniques such as gross morphological scoring, scanning electron microscopy, histological scoring, and micro-computed tomography were used. In this study, ACLT was proven to successfully reproduce early OA articular characteristics found in humans. HA and HA-4AR hydrogels were found to be moderately protective for cartilage as highlighted by μCT. The HA-4AR was the only formulation able to decrease synovial membrane hypertrophy occurring in OA. Finally, the hybrid HA-reacetylated chitosan hydrogel surprisingly led to increased subchondral bone remodeling and cartilage defect formation. This study shows significant effects of two innovative HA modification strategies in an OA rabbit model, which warrant further studies toward more effective viscosupplementation formulations.

Oleuropein or rutin consumption decreases the spontaneous development of osteoarthritis in the Hartley guinea pig

OBJECTIVE

To assess the potential protective effects of three polyphenols oleuropein, rutin and curcumin, on joint ageing and osteoarthritis (OA) development.

DESIGN

Sixty 4-week-old Dunkin-Hartley guinea pigs were randomized into four groups and received daily during 31 weeks either standard guinea pig diet (control group) or a standard guinea pig diet enriched with oleuropein (0.025%), rutin (0.5%) or rutin/curcumin (0.5%/0.25%) association. Biomarkers of OA (Coll2-1, Coll2-1NO2, Fib3-1, Fib3-2, ARGS), as well as inflammation prostaglandin E2 (PGE2) were quantified in the serum. Histological assessments of knee cartilage and synovial membrane were performed at week 4 (five young reference guinea pigs) and week 35.

RESULTS

At week 35, guinea pigs in the control group spontaneously developed significant cartilage lesions with mild synovial inflammation. The histological scores of cartilage lesions and synovitis were well correlated with the increased level of serum biomarkers. Histologically, all treatments significantly reduced the cartilage degradation score (P < 0.01), but only oleuropein significantly decreased the synovial histological score (P < 0.05) and serum PGE2 levels (P < 0.01) compared to the control group. Coll2-1 was decreased by rutin and the combination of rutin/curcumin, Fib3-1 and Fib3-2 were only decreased by the rutin/curcumin mixture, while Coll2-1NO2 was significantly decreased by all treatments (P < 0.05).

CONCLUSION

Oleuropein and rutin ± curcumin significantly slowed down the progression of spontaneous OA lesions in guinea pigs. While no additive effect was seen in the curcumin + rutin group, the differential effects of oleuropein and rutin on inflammatory and cartilage catabolic markers suggest an interesting combination for future studies in OA protection.

Effects of pamidronate disodium on the loss of osteoarthritic subchondral bone and the expression of cartilaginous and subchondral osteoprotegerin and RANKL in rabbits

Background

Osteoarthritis (OA) is a major health problem in the increasingly elderly population. Therefore, it is crucial to prevent and treat OA at an early stage. The present study investigated whether pamidronate disodium (PAM), a bone-loss inhibitor, can significantly prevent or reverse the progression of early anterior cruciate ligament transection (ACLT)-induced OA. Whether therapeutic intervention is associated with regulation of the expression of osteoprotegerin (OPG), receptor activator of nuclear factor-κB ligand (RANKL), metalloproteinase-9 (MMP-9) or Toll-like receptor-4 (TLR-4) in cartilage and/or subchondral bone was also investigated.

Methods

60 New Zealand rabbits were randomized into four groups: Sham-operated (n = 20); ACLT (n = 20); short-term treatment with PAM (PAM-S, n = 10) and long-term treatment with PAM (PAM-L, n = 10). For cartilage and subchondral bone testing, rabbits from Sham and ACLT groups were harvested at 2, 4, 6, and 14 weeks. Rabbits were given PAM from the 4th week after ACLT operation in PAM-S and PAM-L group, and were harvested at 6 and 14 weeks, respectively. Trabecular characteristics and cartilage changes were detected using Micro-CT, safranin O and rapid green staining, respectively. Immunohistochemical staining for OPG and RANKL were also performed. OPG, RANKL, MMP-9 and TLR-4 expression was evaluated by western blot analysis.

Results

Micro-CT and histology analyses indicated that PAM treatment for 2 or 10 weeks could completely prevent or reverse osteoarthritic subchondral bone loss and cartilage surface erosion. Immunohistochemistry and western blot analysis indicated that expression of OPG and RANKL increased, although RANKL expression increased more significantly than that of OPG. Therefore the ratio of OPG to RANKL was lower in the ACLT group. However, the ratio of OPG to RANKL in the PAM group was significantly higher than that in the ACLT group. Additionally, expression of MMP-9 and TLR-4 were upregulated in the ACLT group and downregulated in the PAM treated groups.

Conclusions

PAM can significantly inhibit and even reverse early osteoarthritic subchondral bone loss, thus alleviating the process of cartilaginous degeneration. The mechanisms involved may be associated with the upregulation of OPG expression, and downregulation of RANKL, MMP-9 and TLR-4 expression.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2474-15-370) contains supplementary material, which is available to authorized users.

Parathyroid hormone (1-34) prevents cartilage degradation and preserves subchondral bone micro-architecture in guinea pigs with spontaneous osteoarthritis

OBJECTIVE

To assess whether parathyroid hormone (PTH) (1-34) could improve the micro-structure of subchondral bone, and retard cartilage degradation in a naturally occurring Osteoarthritis (OA) model.

DESIGN

Forty-eight 1-month-old guinea pigs were divided into two groups: 32 were treated by normal saline (NS) and sacrificed at 1, 3, 6 and 9 months of age; the other 16 received PTH (1-34) from 3 months, and were sacrificed at 6 and 9 months. Masson staining and the Osteoarthritis Research Society International (OARSI) grade scores were used to assess cartilage degradation. Immunohistochemistry analyses of type-II collagen, matrix metalloproteinases-13 (MMP-13) and sclerostin (SOST) in the cartilage, osteoprotegerin (OPG) and receptor activator of nuclear factor-kB ligand (RANKL) and PTH receptor (PTH1R) in the cartilage and subchondral bone were performed. Subchondral bone micro-architecture was assessed by micro-computed tomography (micro-CT).

RESULTS

Histological analyses revealed OA occurred at 3 months of age and was more severe with increasing age, and PTH (1-34) reduced the OARSI scores at 6 and 9 months of age. Micro-CT analysis indicated that PTH (1-34) treatment increased the bone volume ratio and bone mineral density (BMD), while retarding the subchondral trabecular bone micro-architectural changes from rod-like to plate-like. Immunohistochemical staining demonstrated that PTH (1-34) treatment increased type-II collagen expression and decreased SOST and MMP-13 expression in the cartilage, while elevating the PTH1R, OPG/RANKL expression ratio in the cartilage and subchondral trabecular bone when compared with the control groups.

CONCLUSIONS

PTH (1-34) can prevent cartilage damage progression and retard the deterioration of subchondral trabecular bone in guinea pigs.

Early intra-articular injection of alendronate reduces cartilage changes and subchondral bone loss in rat temporomandibular joints after ovariectomy

This study investigated the effects of intra-articular injection of alendronate on the mandibular condyle in ovariectomized rats. Sixty rats were divided into five groups: ovariectomy with vehicle treatment alone, early alendronate treatment at ovariectomy, late alendronate treatment at 4 weeks after ovariectomy, sham-operation with vehicle treatment, and normal controls. The changes in cartilage and subchondral bone were evaluated by micro-computed tomography, histology, tartrate-resistant acid phosphatase (TRAP) staining, immunohistochemistry, and real-time quantitative polymerase chain reaction. Compared with late alendronate treatment, early alendronate treatment completely inhibited cartilage thickening (727.6±39.3 vs. 1013.3±51.6; P=0.017) and improved microstructural properties of the subchondral bone, with a higher bone volume ratio (46.4±2.5 vs. 37.5±2.1; P=0.038), trabecular thickness (47.3±1.7 vs. 34.6±1.4; P=0.029), and trabecular number (8.5±0.6 vs. 6.2±0.3; P=0.041) and lower trabecular separation (30.2±1.6 vs. 37.7±2.6; P=0.034). Fewer TRAP-positive cells (4.2±0.2 vs. 6.8±0.4; P=0.019) and a higher OPG/RANKL ratio (0.38±0.01 vs. 0.25±0.03; P=0.043) in the subchondral bone were observed in the animals with early treatment compared to late treatment or ovariectomy/vehicle treatment. In addition, early alendronate treatment blocked the up-regulation of matrix metalloproteinase (MMP)-13 expression in the chondrocytes, whereas late alendronate treatment attenuated the up-regulation of MMP-13 expression. Our results suggest the therapeutic potential of intra-articular alendronate injection in the treatment of osteoporosis-associated temporomandibular disorders.

In vivo effect of two different pulsed electromagnetic field frequencies on osteoarthritis

Osteoarthritis (OA) is a joint pathology characterized by fibrillation, reduced cartilage thickness and subchondral bone sclerosis. There is evidence that pulsed electromagnetic fields (PEMFs) counteract OA progression, but the effect of two different PEMF frequencies has not yet been shown. The aim of this study was to test the effectiveness of PEMFs at two different frequencies (37 and 75 Hz) in a late OA stage in 21-month-old Guinea pigs. After 3 months of 6 h/day PEMF stimulation, histological and histomorphometric analyses of the knees were performed. At both frequencies, PEMFs significantly reduced histological cartilage score, fibrillation index (FI), subchondral bone thickness (SBT) and trabecular number (Tb.N) and increased trabecular thickness (Tb.Th) and separation (Tb.Sp) in comparison to the not treated SHAM group. However, PEMFs at 75 Hz produced significantly more beneficial effects on the histological score and FI than 37 Hz PEMFs. At 75 Hz, PEMFs counteracted cartilage thinning as demonstrated by a significantly higher cartilage thickness values than either those of the SHAM or 37 Hz PEMF-treated groups. Although in severe OA both PEMF frequencies were able to limit its progression, 75 Hz PEMF stimulation achieved the better results.

Meniscectomy leads to early changes in the mineralization distribution of subchondral bone plate

PURPOSE

It is generally recognized that the subchondral bone plate (SBP) is involved in development of osteoarthritis (OA). However, the pathophysiological significance is not yet clear. The goal of this study is to investigate the extent of the changes that occur in SBP of the tibial plateau in the early stages of experimental OA.

METHODS

Forty-three female rabbits were assigned to 5 experimental (n = 8 each group) and one sham group (n = 3). OA was induced by medial meniscectomy in the right knee, the left knee served as control. 2, 4, 8, 12, and 24 weeks after meniscectomy, cartilage damage was evaluated, and bone mineral density (BMD) and mineralization distribution of the SBP was measured by computed tomography osteoabsorptiometry (CT-OAM).

RESULTS

Cartilage damage started 2 weeks after meniscectomy with surface roughening. Cartilage defects increased over time. 24 weeks postoperatively, subchondral bone was exposed. As early as 2 weeks after meniscectomy, BMD in the medial tibial plateau decreased significantly. BMD increased again and reached the values of the non-operated knee 12 weeks postoperatively. In addition, already 4 weeks after meniscectomy a significant shift of the density maximum on the medial tibial plateau, which is normally centrally located toward the margin was observed.

CONCLUSIONS

In conclusion, the results of this study contribute to the concept of early involvement of the SBP in the development of OA. The hypothesis that changes in the SBP occur simultaneously to cartilage damage was confirmed.

Alendronate protects against articular cartilage erosion by inhibiting subchondral bone loss in ovariectomized rats

Osteoporosis (OP) and osteoarthritis (OA) are major health problems in the increasing elderly population, particularly in postmenopausal women, but their relationship remains unclear. The present study investigated whether alendronate (ALN), a potent inhibitor of bone resorption, could protect articular cartilage from degeneration in a combined animal model of OP and OA induced by ovariectomy (OVX). Seventy-eight seven-month-old female Sprague-Dawley rats were assigned into five experimental groups: (1) sham-operated with vehicle treatment, (2) sham-operated with ALN treatment, (3) OVX with vehicle treatment, (4) ALN treatment starting at OVX, and (5) ALN treatment starting at eight weeks after OVX. Histological and micro-CT analyses, together with urine collagen degradation markers, indicated that early ALN treatment completely prevented both subchondral bone loss and cartilage surface erosion induced by OVX. Although late ALN treatment also inhibited subchondral bone loss and significantly reduced cartilage erosion in the OVX rats, these tissues did not completely recover even after 10-weeks of ALN treatment. Quantitative RT-PCR analyses showed that the protective effect of ALN correlated with increased ratio of OPG/RANKL in both subchondral bone and cartilage. Moreover, whereas OVX caused upregulation of expression of matrix metalloproteinases MMP-13 and MMP-9 in the articular cartilage and chondrocytes in the interface between the articular cartilage and subchondral bone, respectively, early ALN treatment blocked whereas late ALN treatment attenuated the upregulation of these catabolic enzymes in the corresponding tissues. Together, these data indicate that the subchondral bone loss plays an important role in OA pathogenesis in the combined OP and OA model and suggest that treatment timing is an important factor for the effectiveness of anti-resorptive drug therapy of combined OP and OA.

Effect of in vitro chondrogenic differentiation of autologous mesenchymal stem cells on cartilage and subchondral cancellous bone repair in osteoarthritis of temporomandibular joint

This study investigated the effects of in vitro chondrogenic differentiated mesenchymal stem cells (MSCs) on cartilage and subchondral cancellous bone in temporomandibular joint osteoarthritis (TMJOA). Four weeks after induction of osteoarthritis (OA), the joints received hylartin solution, non-chondrogenic MSCs or in vitro chondrogenic differentiated MSCs. The changes in cartilage and subchondral cancellous bone were evaluated by histology, reverse transcription polymerase chain reaction and micro-computed tomography (CT). Implanted cells were tracked using Adeno-LacZ labelling. The differentiated MSC-treated group had better histology than the MSC-treated group at 4 and 12 weeks, but no difference at 24 weeks. Increased mRNA expression of collegan II, aggeran, Sox9 and decreased matrix metalloproteinase 13 (MMP13) were observed in differentiated MSC-treated groups compared to the undifferentiated MSC-treated group at 4 weeks. The differentiated MSC-treated group had decreased bone volume fraction, trabecular thickness and bone surface density, and increased trabecular spacing in the subchondral cancellous bone than the undifferentiated MSC-treated group. Transplanted cells were observed at cartilage, subchondral bone, and the synovial membrane lining at 4 weeks. Intra-articular injection of MSCs could delay the progression of TMJOA, and in vitro chondrogenic induction of MSCs could enhance the therapeutic effects. This provides new insights into the role of MSCs in cell-based therapies for TMJOA.

Intra-articular injection of hyaluronan restores the aberrant expression of matrix metalloproteinase-13 in osteoarthritic subchondral bone

Subchondral bone is a candidate for treatment of osteoarthritis (OA). We investigated the effects of intra-articular injection of hyaluronan (IAI-HA) on subchondral bone in rabbit OA model. OA was induced by anterior cruciate ligament transection, with some rabbits receiving IAI-HA. OA was graded morphologically, and expression of mRNA was assessed by real-time RT-PCR. Tissue sections were stained with hyaluronan-binding protein, and penetration of fluorescent hyaluronan was assessed. The in vitro inhibitory effect of hyaluronan on MMP-13 was analyzed in human osteoarthritic subchondral bone osteoblasts (OA Ob) by real-time RT-PCR and ELISA. Binding of hyaluronan to OA Ob via CD44 was assessed by immunofluorescence cytochemistry. Expression of MMP-13 and IL-6 mRNA in cartilage and subchondral bone, and morphological OA grade, increased over time. IAI-HA ameliorated the OA grade and selectively suppressed MMP-13 mRNA in subchondral bone. IAI-HA enhanced the hyaluronan staining of subchondral bone marrow cells and osteocyte lacunae. Fluorescence was observed in the subchondral bone marrow space. In OA Ob, hyaluronan reduced the expression and production of MMP-13, and anti-CD44 antibody blocked hyaluronan binding to OA Ob. These findings indicate that regulation of MMP-13 in subchondral bone may be a critical mechanism during IAI-HA.

Insulin-like growth factor-1 suspended in hyaluronan improves cartilage and subchondral cancellous bone repair in osteoarthritis of temporomandibular joint

This study sought to evaluate the effects of intra-articular injection of insulin-like growth factor-1 (IGF-1) suspended in hyaluronan (HA) on the cartilage and subchondral cancellous bone repair in osteoarthritis (OA) of the temporomandibular joint (TMJ). Disc perforation was performed bilaterally in rabbit TMJs to induce OA. Four groups of animals (n=12) received OA induction only, and either intra-articular HA injection alone, intra-articular IGF-1 injection alone, or a combination of HA and IGF-1 injection. All therapy was begun 4 weeks after OA induction. The animals were killed 12 or 24 weeks after the first injection, for histology and micro-CT examinations. Two additional animals were used as normal controls. Typical cartilage and subchondral cancellous bone lesions were observed in the OA group. No protective effect on cartilage and subchondral cancellous bone was found in the HA or IGF-1 alone groups. Better histological repair and nearly normal micro-architectural properties of the subchondral cancellous bone were observed in the HA+IGF-1 group compared with the HA or IGF-1 alone groups. HA may be used as an effective carrier for intra-articular injection of IGF-1 and the combination of HA/IGF-1 shows promise as a new rational approach to therapy of TMJ OA.

The OARSI histopathology initiative - recommendations for histological assessments of osteoarthritis in the guinea pig

OBJECTIVE

This review focuses on the criteria for assessing osteoarthritis (OA) in the guinea pig at the macroscopic and microscopic levels, and recommends particular assessment criteria to assist standardization in the conduct and reporting of preclinical trails in guinea pig models of OA.

METHODS

A review was conducted of all OA studies from 1958 until the present that utilized the guinea pig. The PubMed database was originally searched August 1, 2006 using the following search terms: guinea pig and OA. We continued to check the database periodically throughout the process of preparing this chapter and the final search was conducted January 7, 2009. Additional studies were found in a review of abstracts from the OsteoArthritis Research Society International (OARSI) conferences, Orthopaedic Research Society (ORS) conferences, and literature related to histology in other preclinical models of OA reviewed for relevant references. Studies that described or used systems for guinea pig joint scoring on a macroscopic, microscopic, or ultrastructural basis were included in the final comprehensive summary and review. General recommendations regarding methods of OA assessment in the guinea pig were derived on the basis of a comparison across studies and an inter-rater reliability assessment of the recommended scoring system.

RESULTS

A histochemical-histological scoring system (based on one first introduced by H. Mankin) is recommended for semi-quantitative histological assessment of OA in the guinea pig, due to its already widespread adoption, ease of use, similarity to scoring systems used for OA in humans, its achievable high inter-rater reliability, and its demonstrated correlation with synovial fluid biomarker concentrations. Specific recommendations are also provided for histological scoring of synovitis and scoring of macroscopic lesions of OA.

CONCLUSIONS

As summarized herein, a wealth of tools exist to aid both in the semi-quantitative and quantitative assessment of OA in the guinea pig and provide a means of comprehensively characterizing the whole joint organ. In an ongoing effort at standardization, we recommend specific criteria for assessing the guinea pig model of OA as part of an OARSI initiative, termed herein the OARSI-HISTOgp recommendations.

Microarchitectural adaptations in aging and osteoarthrotic subchondral bone issues

The human skeleton optimizes its microarchitecture by elaborate adaptations to mechanical loading during development and growth. The mechanisms for adaptation involve a multistep process of cellular mechanotransduction stimulating bone modelling, and remodeling resulting in either bone formation or resorption. This process causes appropriate microarchitectural changes tending to adjust and improve the bone structure to its prevailing mechanical environment. Normal individual reaches peak bone mass at age between 25 and 30 years, and thereafter bone mass declines with age in both genders. The bone loss is accompanied by microarchitectural deterioration resulting in reduced mechanical strength likely leading to fragility fractures. With aging, inevitable bone loss occurs, which is frequently the cause of osteoporosis; and inevitable bone and joint degeneration happens, which often results in osteoarthrosis. These diseases are among the major health care problems in terms of socio-economic costs. The overall goals of the current series of studies were to investigate the age-related and osteoarthrosis (OA) related changes in the 3-D microarchitectural properties, mechanical properties, collagen and mineral quality of subchondral cancellous and cortical bone tissues. The studies included mainly two parts. For human subjects: aging- (I–IV) and early OArelated (V–VI) changes in cancellous bone properties were assessed. For OA guinea pig models (VII–IX), three topics were studied: firstly, the spontaneous, age-related development of guinea pig OA; secondly, the potential effects of hyaluronan on OA subchondral bone tissues; and thirdly, the effects on OA progression of an increase in subchondral bone density by inhibition of bone remodeling with a bisphosphonate. These investigations aimed to obtain more insight into the age-related and OA-related subchondral bone adaptations.

Cancer-induced bone loss and associated pain-related behavior is reduced by risedronate but not its phosphonocarboxylate analog NE-10790

Prostate, breast and lung cancers readily develop bone metastases which lead to fractures, hypercalcemia and pain. Malignant growth in the bones depends on osteoclast-mediated bone resorption and in this regard bisphosphonate compounds, which have high-bone affinity and inhibit osteoclast activity, have been found to alleviate bone cancer symptoms. In this study, the bisphosphonate risedronate and its phosphonocarboxylate derivative NE-10790 was tested in a murine bone cancer pain model. Risedronate decreased bone cancer-related bone destruction and pain-related behavior and decreased the spinal expression of glial fibrillary acidic protein, whereas NE-10790 had no effect on these parameters. Furthermore, risedronate but not NE-10790 induced dose-dependent toxicity in NCTC-2472 cells in vitro. Furthermore, the direct toxic effect of risedronate on tumor cells observed in vitro opens the possibility that a direct toxic effect on tumor cells may also be present in vivo and be related to the efficacy of bisphosphonate compounds. In conclusion, these results suggest that risedronate treatment may lead to an increased life quality, in patient suffering from bone cancer, in terms of decreased osteolysis and pain, and merits further study.

Use of routine clinical multimodality imaging in a rabbit model of osteoarthritis--part II: bone mineral density assessment

OBJECTIVE

To assess bone mineral density (BMD) at different depths from the articular surface in vivo and temporally in a rabbit model of osteoarthritis (OA) using clinical computed tomography (CT) equipment.

METHODS

The knee joints of rabbits (N=10 with Anterior cruciate ligament transection (ACLT) and contralateral sham joints, and N=6 unoperated controls) were scanned in a transverse image plane with a single-slice helical CT scanner. BMD was calculated at defined depths from the articular surface to the growth plate in the lateral femoral condyle (LFC), medial femoral condyle (MFC), lateral tibial plateau (LTP) and medial tibial plateau (MTP). Baseline BMD was measured at 2 weeks before surgery, and then repeated at weeks 2, 4 and 8 post-surgery in all 10 operated rabbits, and again at week 12 in five of the operated rabbits and at weeks -2 and 8 in the six control rabbits.

RESULTS

In the control joints, BMD decreased with increasing distance into the epiphysis and remained stable over time within each depth. A significant reduction in BMD was observed at week 2 post-operatively in three compartments (LFC, MFC and MTP) in the ACLT joints and persisted to week 12. A modest reduction in BMD occurred in the LTP and MTP of the sham joints at week 12 alone.

CONCLUSION

Clinical CT equipment permitted rapid, repeated, in vivo, non-invasive BMD assessment in a rabbit model of OA. A marked BMD reduction was measured with progression of OA until the end point at 12 weeks.

Micro-CT analysis of experimental Candida osteoarthritis in rats

Experimental osteoarthritis induced by Candida albicans in rats was studied using micro-computed tomography (micro-CT). When C. albicans cells at a nonlethal dose were intravenously injected into 40 rats, joint swelling was induced in 24 rats. Two or more joints were affected in 10 of the 24 rats. Tarsal regions of the hind paw were affected most frequently, followed by elbows of the fore paw. Micro-CT analysis in vivo showed that erosions of the affected tarsal joint bones were apparent several days after the onset of swelling. Thereafter, severe surface roughness and disintegration in the joint bones progressed during the development of arthritis. Three-dimensional (3D) trabecular microstructures and changes in 3D bone parameters were characterized ex vivo with calcanei from affected hind paws. Three-dimensional morphology showed coarsening of the trabecular distribution and weakening of the trabecular connectivity in arthritic bones. These morphological changes were quantitatively confirmed by changes in 3D bone parameters measured from consecutively scanned bone slices. Micro-CT has been shown to be useful for quantifying morphological changes occurring in Candida arthritic bones.

Measurement of knee cartilage thickness using MRI: a reproducibility study in a meniscectomized guinea pig model of osteoarthritis

The in vivo precision (reproducibility) of quantitative MRI is of particular importance in osteoarthritis (OA) progression of small magnitude and response to therapy. In this study, three-dimensional high-resolution MRI performed at 7 T was used to assess the short-term reproducibility of measurements of mean tibial cartilage thickness in a meniscectomized guinea pig model of OA. MR image acquisition was repeated five times in nine controls (SHAM) and 10 osteoarthritic animals 3 months after meniscectomy (MNX), in vivo. The animals were then killed for histomorphometric assessment and correlation with the MRI-based measurements. Medial tibial cartilage thickness was measured on MR images using semi-automatic dedicated 3D software developed in-house. The reproducibility of measurements of cartilage thickness was assessed by five repeated MRI examinations with a short recovery delay between examinations (48 h). The computed coefficients of variation were 8.9% for the SHAM group and 8.2% for the MNX group. The coefficients of variation were compatible with expected thickness variations between normal and pathological animals. A positive agreement and significant partial correlation (Spearman r' = 0.74; P < 0.01) between the MRI and histomorphometric data was established. Three-dimensional high-resolution MRI is a promising non-invasive research tool for in vivo follow-up. This modality could be used for staging and monitoring therapy response in small-animal models of OA.

Study of subchondral bone adaptations in a rodent surgical model of OA using in vivo micro-computed tomography

OBJECTIVE

To non-invasively investigate the changes to epiphyseal bone occurring in a longitudinal pre-clinical model of osteoarthritis (OA) using in vivo micro-computed tomography (micro-CT).

DESIGN

In vivo micro-CT images were acquired using a bench-top micro-CT scanner, which produces three-dimensional data with isotropic voxel spacing of 0.046 mm. Male rodents were scanned prior to surgical destabilization, consisting of anterior cruciate ligament transection and partial medial menisectomy (ACLX). Subsequent scans were performed every 4 weeks post-ACLX, for up to 5 months. Volumetric bone mineral density (vBMD) was measured in specific, anatomically segmented regions within each image. The ACLX rodent data were compared with the contralateral non-operated hind limb of the same animal, as well as a sham-operated group (SHAM) of animals, for each time point. End-point histology compared changes to cartilage and bone between the ACLX and control animals.

RESULTS

The micro-CT protocol produced sufficient spatial resolution and signal-to-noise ratio (SNR=19) to quantify subchondral bone pathology, with an acceptable entrance exposure to radiation (0.36 Gy). Significantly lower vBMD was measured in the ACLX group, vs SHAM rodents, at 1, 4, and 5 months post-surgery (P<0.05). Qualitative observations of ACLX joints revealed significant loss of cartilage, subchondral bone cysts, and calcification of tendon similar to changes found in humans.

CONCLUSIONS

This study demonstrates in vivo micro-CT as an effective method for investigating the development of rodent knee OA longitudinally. This method can be applied, in future pre-clinical trials, to non-destructively monitor the efficacy of pharmacological interventions.

The effects of bone remodeling inhibition by alendronate on three-dimensional microarchitecture of subchondral bone tissues in guinea pig primary osteoarthrosis

We assessed whether increase of subchondral bone density enhances cartilage stress during impact loading, leading to progressive cartilage degeneration and accelerated osteoarthrosis (OA) progression. Sixty-six male guinea pigs were randomly divided into six groups. During a 9-week treatment period, four groups received twice-weekly subcutaneous injections of alendronate (ALN) in two doses: two groups received 10 microg/kg and two groups received 50 microg/kg. The two control groups received vehicle. After 9 weeks, one 10 microg/kg ALN group, one 50 microg/kg ALN group, and one control group were killed. The remaining three groups (17-week groups) were left for an additional 8 weeks, receiving the same treatment regimen before death. The left proximal tibiae were scanned by micro-computed tomography to quantify the microarchitecture of subchondral bone, followed by mechanical testing and determination of collagen and mineral. The control groups had typical OA-related cartilage degeneration at 9 and 17 weeks, whereas the 50 microg/kg ALN group had even worse degeneration in the medial condyle. It is unclear whether there is a direct or a secondary effect of ALN on the cartilage. The 9-week ALN group had significantly greater subchondral plate thickness. The 9- and 17-week groups had similar changes of cancellous bone microarchitecture, with greater volume fraction and connectivity and an extremely plate-like structure. The 9-week ALN group had greater bone mineral concentration, and the 17-week ALN group had reduced collagen concentration and greater mineral concentration. Treatment with ALN did not significantly change the mechanical properties of the cancellous bone.

Role of subchondral bone in osteoarthritis development: a comparative study of two strains of guinea pigs with and without spontaneously occurring osteoarthritis

OBJECTIVE

To evaluate the relationships among cartilage and subchondral bone before and after the onset of cartilage degeneration in the Hartley guinea pig model of spontaneous osteoarthritis (OA) as compared with those in Weiser-Maple guinea pigs, which do not develop OA.

METHODS

Mice from each strain were used at ages 2, 3, 5, and 8 months (n = 7 at each time point). The region observed was the medial tibial plateau. Cartilage degeneration was evaluated histologically. Subchondral bone structure was evaluated based on subchondral bone plate thickness and subchondral cancellous bone trabecular parameters calculated from the microfocal computed tomography 3-dimensional reconstruction image. The bone mineral density (BMD) of the subchondral cancellous bone as well as levels of urinary N-telopeptide of type I collagen (NTX) and serum osteocalcin (OC) were measured.

RESULTS

In Hartley guinea pigs, the number of chondrocytes in the surface layer started to decrease at 3 months. At 8 months, fibrillation expanded to the radial zone. In Weiser-Maple guinea pigs, no cartilage degeneration was noted even at 8 months. Subchondral bone plate thickness was significantly lower in Hartley guinea pigs than in Weiser-Maple guinea pigs at 2 months. The subchondral bone had a rod-like and convex structure at 2 months in Hartley guinea pigs. BMD was significantly lower in Hartley guinea pigs than in Weiser-Maple guinea pigs at 2 months. The serum OC level was significantly higher in Hartley guinea pigs than in Weiser-Maple guinea pigs at 2 months and 3 months, whereas the urinary NTX level was significantly lower in Hartley guinea pigs at 3 months.

CONCLUSION

Subchondral bone is fragile, and bone formation may be promoted in subchondral bone before the onset of cartilage degeneration in Hartley guinea pigs. Subchondral bone may be involved in the development of OA.

Age-related three-dimensional microarchitectural adaptations of subchondral bone tissues in guinea pig primary osteoarthrosis

We explored potential mechanisms of the microarchitectural adaptations of subchondral bone tissues in a guinea pig primary osteoarthrosis (OA) model. We harvested proximal tibiae of male Dunkin-Hartley (Charles River strain) guinea pigs at 3, 6, 9, 12, and 24 months of age (10 in each group). These proximal tibiae were scanned by micro-computed tomography to quantify the three-dimensional microarchitecture of the subchondral plate, cancellous bone, and cortical bone. Subsequently, the bones were compression-tested to determine their mechanical properties. Furthermore, bone collagen, bone mineral, and bone density were determined. Mankin's score corresponded to OA grading from absent or minimal cartilage degeneration in 3-month-old to severe degeneration in 24-month-old guinea pigs. In young guinea pigs, the volume fraction and thickness of the subchondral plate markedly increased from 3 to 6 months, whereas the volume fraction of the subchondral cancellous bone displayed an initial decline followed by an increase. With age, the trabeculae increased in thickness, changed from rod-like to plate-like, and became more axially oriented. An increasing ratio of bone collagen to mineral in subchondral bone indicated undermineralized bone tissues. In subchondral cancellous bone, Young's modulus was maximal at 6 months of age, whereas ultimate stress and failure energy showed a gradual increase with age. The findings show pronounced alterations of the microarchitecture and bone matrix composition of the subchondral bone. These alterations did not appear to follow the same pattern as in normal aging and may have different influences on the resulting mechanical properties.

Effects of hyaluronan on three-dimensional microarchitecture of subchondral bone tissues in guinea pig primary osteoarthrosis

Hyaluronan (HA) has received increasing interest as a potential agent in therapeutic intervention in osteoarthrosis (OA). HA has been shown to reduce arthritic lesions in experimental animal models of articular cartilage injury. This study was to investigate the effects of high molecular weight HA intra-articular injection on subchondral bone tissues. Fifty-six male guinea pigs were randomly divided into 5 groups. During the initial 2.5-month period, three groups received intra-articular injection of HA 0.4 mg/kg/week for 5 weeks in both knee joints. Two control groups received vehicle. After 2.5 months, one HA group and one control group were sacrificed. The remaining 3 groups (5.5-month groups) were left for an additional 3 months before sacrifice during which time one HA group received additional 5 weeks injections, one HA group received no more injections, and the control group received vehicle. The left tibiae were harvested and micro-CT scanned to quantify three-dimensional microarchitecture of subchondral bone plate, cancellous bone and cortical bone, followed by mechanical testing and collagen and mineral determinations. All HA-treated groups had almost normal cartilage, whereas the control groups had typical OA-related cartilage degradation. In the 2.5-month group, HA resulted in significantly decreased subchondral plate volume fraction and thickness and HA-treated cancellous bone had significantly lower bone volume fraction, and typical rod-like structure. After 5.5 months, these changes were more pronounced, with an additional marked decrease in connectivity and bone surface density. HA-treated cortical bone had significantly greater volume fraction at both observation times. HA groups had greater bone mineral concentration and reduced collagen to mineral ratio with similar mechanical properties of cancellous bone but less stiff cortical bone. The effects of HA on cartilage and subchondral bone were maintained when treatment was discontinued. In summary, HA effectively protects against cartilage degeneration, decreases subchondral bone density and thickness, changes trabecular structure toward rod-like, so that subchondral bone becomes more compliant and thereby reduces cartilage stress during impact loading. HA preserved cancellous bone mechanical properties by increasing bone mineralization. Early HA administration is effective for intervention of OA initiation and progression, and short-term early HA treatment is sufficient to maintain treatment effects.