Fibular head avulsion fractures accompanying operative treated medial tibial plateau fractures

OBJECTIVE

The aims of this work are to determine how frequently medial tibial plateau fractures are accompanied by fibular head avulsion fractures and evaluate the sensitivity of radiographs detecting them, and also to assess if the presence of fibular fracture is correlated with long-term functional outcome and peroneal nerve damage.

MATERIALS AND METHODS

A retrospective chart review of operated patients with medial tibial plateau fractures at level I trauma center during 2002-2008 was performed. From 63 patients imaged preoperatively, 59 had CT and radiographs, three had only CT, and one only radiograph. The presence and fragment size of fibular fracture were retrospectively evaluated. Body mass index (BMI) and functional outcome measurements (the Modified Lysholm knee score and WOMAC) were available for 46 patients.

RESULTS

Fourteen out of 63 patients (22.2%) had fibular fractures. Of the 59 patients with both CT and radiographs, 12 had fibular fractures, and of these, nine were seen with both modalities and three only in CT. Functional scores were available for ten patients with fibular fracture. Patients with fibular fracture seen on radiographs had a significantly higher score on WOMAC function (26 vs. 7; p = 0.027). The patients with fibular fractures had also higher BMI (p = 0.035). Of the six patients with peroneal nerve damage, 50% had fibular fracture.

CONCLUSIONS

In patients with operatively treated medial tibial plateau fracture, the fibular fractures are relatively common. Detecting it is important, as it may be associated with worse functional scores and peroneal nerve paresis. Some fibular fractures may remain undetected on radiographs, hence preoperative CT is recommended.

Radiographical measurements for distal intra-articular fractures of the radius using plain radiographs and cone beam computed tomography images

OBJECTIVE

Operative treatment of an intra-articular distal radius fracture is one of the most common procedures in orthopedic and hand surgery. The intra- and interobserver agreement of common radiographical measurements of these fractures using cone beam computed tomography (CBCT) and plain radiographs were evaluated.

MATERIALS AND METHODS

Thirty-seven patients undergoing open reduction and volar fixation for a distal radius fracture were studied. Two radiologists analyzed the preoperative radiographs and CBCT images. Agreement of the measurements was subjected to intra-class correlation coefficient and the Bland-Altman analyses.

RESULTS

Plain radiographs provided a slightly poorer level of agreement. For fracture diastasis, excellent intraobserver agreement was achieved for radiographs and good or excellent agreement for CBCT, compared to poor interobserver agreement (ICC 0.334) for radiographs and good interobserver agreement (ICC 0.621) for CBCT images. The Bland-Altman analyses indicated a small mean difference between the measurements but rather large variation using both imaging methods, especially in angular measurements.

CONCLUSIONS

For most of the measurements, radiographs do well, and may be used in clinical practice. Two different measurements by the same reader or by two different readers can lead to different decisions, and therefore a standardization of the measurements is imperative. More detailed analysis of articular surface needs cross-sectional imaging modalities.

Osteogenic differentiation of mesenchymal stromal cells in two-dimensional and three-dimensional cultures without animal serum

INTRODUCTION

Bone marrow-derived mesenchymal stromal cells (MSCs) have been intensely studied for the purpose of developing solutions for clinical tissue engineering. Autologous MSCs can potentially be used to replace tissue defects, but the procedure also carries risks such as immunization and xenogeneic infection. Replacement of the commonly used fetal calf serum (FCS) with human platelet lysate and plasma (PLP) to support cell growth may reduce some of these risks. Altered media could, however, influence stem cell differentiation and we address this experimentally.

METHODS

We examined human MSC differentiation into the osteoblast lineage using in vitro two- and three-dimensional cultures with PLP or FCS as cell culture medium supplements. Differentiation was followed by quantitative polymerase chain reaction, and alkaline phosphatase activity, matrix formation and matrix calcium content were quantified.

RESULTS

Three-dimensional culture, where human MSCs were grown on collagen sponges, markedly stimulated osteoblast differentiation; a fourfold increase in calcium deposition could be observed in both PLP and FCS groups. PLP-grown cells showed robust osteogenic differentiation both in two- and three-dimensional MSC cultures. The calcium content of the matrix in the two-dimensional PLP group at day 14 was 2.2-fold higher in comparison to the FCS group (p < 0.0001), and at day 21 it was still 1.3-fold higher (p < 0.001), suggesting earlier calcium accumulation to the matrix in the PLP group. This was supported by stronger Alizarin Red staining in the PLP group at day 14. In two-dimesional PLP cultures, cellular proliferation appeared to decrease during later stages of differentiation, while in the FCS group the number of cells increased throughout the experiment. In three-dimensional experiments, the PLP and FCS groups behaved more congruently, except for the alkaline phosphatase activity and mRNA levels which were markedly increased by PLP.

CONCLUSIONS

Human PLP was at least equal to FCS in supporting osteogenic differentiation of human MSCs in two- and three-dimensional conditions; however, proliferation was inferior. As PLP is free of animal components, and thus represents reduced risk for xenogeneic infection, its use for human MSC-induced bone repair in the clinic by the three-dimensional live implants presented here appears a promising therapy option.

A bioactive hybrid three-dimensional tissue-engineering construct for cartilage repair

The aim was to develop a hybrid three-dimensional-tissue engineering construct for chondrogenesis. The hypothesis was that they support chondrogenesis. A biodegradable, highly porous polycaprolactone-grate was produced by solid freeform fabrication. The polycaprolactone support was coated with a chitosan/polyethylene oxide nanofibre sheet produced by electrospinning. Transforming growth factor-β3-induced chondrogenesis was followed using the following markers: sex determining region Y/-box 9, runt-related transcription factor 2 and collagen II and X in quantitative real-time polymerase chain reaction, histology and immunostaining. A polycaprolactone-grate and an optimized chitosan/polyethylene oxide nanofibre sheet supported cellular aggregation, chondrogenesis and matrix formation. In tissue engineering constructs, the sheets were seeded first with mesenchymal stem cells and then piled up according to the lasagne principle. The advantages of such a construct are (1) the cells do not need to migrate to the tissue engineering construct and therefore pore size and interconnectivity problems are omitted and (2) the cell-tight nanofibre sheet and collagen-fibre network mimic a cell culture platform for mesenchymal stem cells/chondrocytes (preventing escape) and hinders in-growth of fibroblasts and fibrous scarring (preventing capture). This allows time for the slowly progressing, multiphase true cartilage regeneration.

Identification of histamine receptor subtypes in skeletal myogenesis

To date, conventional and/or novel histamine receptors (HRs) have not been investigated in mouse skeletal myogenesis. Therefore, the present study aimed to investigate the HR-subtypes in skeletal myogenesis. The myogenesis of C2C12 skeletal myoblasts was evaluated using desmin, myogenin and myosin heavy chain (Myh) as early, intermediate and late differentiation markers, respectively. Reverse transcription-quantitative polymerase chain reaction and immunostaining were performed and the messenger RNA (mRNA) expression levels of the HR-subtypes and markers were determined. H₁R mRNA was found to be highly expressed in myoblasts at day 0; however, the expression levels were reduced as differentiation progressed. By contrast, H₂R mRNA expression remained constant, while H₃R mRNA expression increased by 28-, 103- and 198-fold at days 2, 4 and 6 compared with the baseline level (day 0), respectively. In addition, Myh expression increased by 7,718-, 94,487- and 286,288-fold on days 2, 4 and 6 compared with the baseline expression level (day 0). Weak positive staining of the cells for H₃R protein was observed on day 2, whereas highly positive staining was observed on days 4 and 6. HR expression during myogenesis was, in part, regulated by the stage of differentiation. These results along with previous findings indicated possible involvement of H₁R in the regulation of progenitor cell mitogenesis and of H₂R in the relaxation of acetylcholine-stimulated contraction of muscle cells, following the activation of professional histamine-producing cells, including mast cells. By contrast, H₃R may participate in the regulation of specialized myocyte functions, potentially by maintaining the relaxed state under the influence of constitutive H₃R activity and low histamine concentrations, locally produced/released by non-professional histamine-producing cells.

Label-free imaging of adipogenesis by coherent anti-stokes Raman scattering microscopy

Label-free imaging technologies to monitor the events associated with early, intermediate and late adipogenic differentiation in multipotent mesenchymal stromal cells (MSCs) offer an attractive and convenient alternative to conventional fixative based lipid dyes such as Oil Red O and Sudan Red, fluorescent labels such as LipidTOX, and more indirect methods such as qRT-PCR analyses of specific adipocyte differentiation markers such as peroxisome PPARγ and LPL. Coherent anti-Stokes Raman scattering (CARS) microscopy of live cells is a sensitive and fast imaging method enabling evaluation of the adipogenic differentiation with chemical specificity. CARS microscopy is based on imaging structures of interest by displaying the characteristic intrinsic vibrational contrast of chemical bonds. The method is nontoxic, non-destructive, and minimally invasive, thus presenting a promising method for longitudinal analyses of live cells and tissues. CARS provides a coherently emitted signal that is much stronger than the spontaneous Raman scattering. The anti-Stokes signal is blue shifted from the incident wavelength, thus reducing the non-vibrational background present in most biological materials. In this chapter, we aim to provide a detailed approach on how to induce adipogenic differentiation in MSC cultures, and present our methods related to label-free CARS imaging of the events associated with the adipogenesis.

Osteogenic differentiation on DLC-PDMS-h surface

The hypothesis was that anti-fouling diamond-like carbon polydimethylsiloxane hybrid (DLC-PDMS-h) surface impairs early and late cellular adhesion and matrix-cell interactions. The effect of hybrid surface on cellular adhesion and cytoskeletal organization, important for osteogenesis of human mesenchymal stromal cells (hMSC), where therefore compared with plain DLC and titanium (Ti). hMSCs were induced to osteogenesis and followed over time using scanning electron microscopy (SEM), time-of-flight secondary ion mass spectrometry (ToF-SIMS), immunofluorescence staining, quantitative real-time polymerase chain reaction (qRT-PCR), and hydroxyapatite (HA) staining. SEM at 7.5 hours showed that initial adherence and spreading of hMSC was poor on DLC-PDMS-h. At 5 days some hMSC were undergoing condensation and apoptotic fragmentation, whereas cells on DLC and Ti grew well. DAPI-actin-vinculin triple staining disclosed dwarfed cells with poorly organized actin cytoskeleton-focal complex/adhesion-growth substrate attachments on hybrid coating, whereas spread cells, organized microfilament bundles, and focal adhesions were seen on DLC and in particular on Ti. Accordingly, at day one ToF-SIMS mass peaks showed poor protein adhesion to DLC-PDMS-h compared with DLC and Ti. COL1A1, ALP, OP mRNA levels at days 0, 7, 14, 21, and/or 28 and lack of HA deposition at day 28 demonstrated delayed or failed osteogenesis on DLC-PDMS-h. Anti-fouling DLC-PDMS-h is a poor cell adhesion substrate during the early protein adsorption-dependent phase and extracellular matrix-dependent late phase. Accordingly, some hMSCs underwent anoikis-type apoptosis and failed to complete osteogenesis, due to few focal adhesions and poor cell-to-ECM contacts. DLC-PDMS-h seems to be a suitable coating for non-integrating implants/devices designed for temporary use.

Sample processing, protocol, and statistical analysis of the time-of-flight secondary ion mass spectrometry (ToF-SIMS) of protein, cell, and tissue samples

Time-of-flight secondary ion mass spectrometry (ToF-SIMS) is increasingly being used in analysis of biological samples. For example, it has been applied to distinguish healthy and osteoarthritic human cartilage. This chapter discusses ToF-SIMS principle and instrumentation including the three modes of analysis in ToF-SIMS. ToF-SIMS sets certain requirements for the samples to be analyzed; for example, the samples have to be vacuum compatible. Accordingly, sample processing steps for different biological samples, i.e., proteins, cells, frozen and paraffin-embedded tissues and extracellular matrix for the ToF-SIMS are presented. Multivariate analysis of the ToF-SIMS data and the necessary data preprocessing steps (peak selection, data normalization, mean-centering, and scaling and transformation) are discussed in this chapter.

Toll-like receptors in human chondrocytes and osteoarthritic cartilage

BACKGROUND AND PURPOSE

Degenerating cartilage releases potential danger signals that react with Toll-like receptor (TLR) type danger receptors. We investigated the presence and regulation of TLR1, TLR2, and TLR9 in human chondrocytes.

METHODS

We studied TLR1, TLR2, TLR4, and TLR9 mRNA (qRT-PCR) and receptor proteins (by immunostaining) in primary mature healthy chondrocytes, developing chondrocytes, and degenerated chondrocytes in osteoarthritis (OA) tissue sections of different OARSI grades. Effects of a danger signal and of a pro-inflammatory cytokine on TLRs were also studied.

RESULTS

In primary 2D-chondrocytes, TLR1 and TLR2 were strongly expressed. Stimulation of 2D and 3D chondrocytes with a TLR1/2-specific danger signal increased expression of TLR1 mRNA 1.3- to 1.8-fold, TLR2 mRNA 2.6- to 2.8-fold, and TNF-α mRNA 4.5- to 9-fold. On the other hand, TNF-α increased TLR1 mRNA] expression 16-fold, TLR2 mRNA expression 143- to 201-fold, and TNF-α mRNA expression 131- to 265-fold. TLR4 and TLR9 mRNA expression was not upregulated. There was a correlation between worsening of OA and increased TLR immunostaining in the superficial and middle cartilage zones, while chondrocytes assumed a CD166(×) progenitor phenotype. Correspondingly, TLR expression was high soon after differentiation of mesenchymal stem cells to chondrocytes. With maturation, it declined (TLR2, TLR9).

INTERPRETATION

Mature chondrocytes express TLR1 and TLR2 and may react to cartilage matrix/chondrocyte-derived danger signals or degradation products. This leads to synthesis of pro-inflammatory cytokines, which stimulate further TLR and cytokine expression, establishing a vicious circle. This suggests that OA can act as an autoinflammatory disease and links the old mechanical wear-and-tear concept with modern biochemical views of OA. These findings suggest that the chondrocyte itself is the earliest and most important inflammatory cell in OA.

Macrophages-Key cells in the response to wear debris from joint replacements

The generation of wear debris is an inevitable result of normal usage of joint replacements. Wear debris particles stimulate local and systemic biological reactions resulting in chronic inflammation, periprosthetic bone destruction, and eventually, implant loosening, and revision surgery. The latter may be indicated in up to 15% patients in the decade following the arthroplasty using conventional polyethylene. Macrophages play multiple roles in both inflammation and in maintaining tissue homeostasis. As sentinels of the innate immune system, they are central to the initiation of this inflammatory cascade, characterized by the release of proinflammatory and pro-osteoclastic factors. Similar to the response to pathogens, wear particles elicit a macrophage response, based on the unique properties of the cells belonging to this lineage, including sensing, chemotaxis, phagocytosis, and adaptive stimulation. The biological processes involved are complex, redundant, both local and systemic, and highly adaptive. Cells of the monocyte/macrophage lineage are implicated in this phenomenon, ultimately resulting in differentiation and activation of bone resorbing osteoclasts. Simultaneously, other distinct macrophage populations inhibit inflammation and protect the bone-implant interface from osteolysis. Here, the current knowledge about the physiology of monocyte/macrophage lineage cells is reviewed. In addition, the pattern and consequences of their interaction with wear debris and the recent developments in this field are presented.

Laminin production and basement membrane deposition by mesenchymal stem cells upon adipogenic differentiation

The aim was to study laminin (LM) synthesis, integration, and deposition into the basement membrane (BM) during adipogenesis. Human bone marrow-derived mesenchymal stromal cells (MSCs) were induced along the adipogenic lineage. LM chain mRNA and protein levels were followed using quantitative real-time polymerase chain reaction (qRT-PCR), immunofluorescence (IF) staining, transmission electron microscopy (TEM), and immunoprecipitation. MSCs produced low levels of LM mRNAs but were not surrounded by BM in IF and TEM imaging. LM-α4, LM-β1, and LM-γ1 mRNAs increased during adipogenesis 3.9-, 5.8-, and 2.8-fold by day 28. LM-411 was immunoprecipitated from the ECM of the differentiated cells. Immunostaining suggested deposition of LM-411 and some LM-421. BM build-up was probably organized in part by integrin (Int) α6β1. At day 28, TEM images revealed BM-like structures around fat droplet-containing cells. The first signs of BM formation and Int α6β1 were seen using IF imaging at day 14. Laminin-411 and Int α6β1 were expressed in vivo in mature human subcutaneous fat tissue. Undifferentiated human MSCs did not organize LM subunits into BM, whereas LM-411 and some LM-421 are precipitated in the BM around adipocytes. This is the first demonstration of LM-411 precipitation during hMSC adipogenesis around adipocytes as a structural scaffold and Int-regulated signaling element.

Do changing toll-like receptor profiles in different layers and grades of osteoarthritis cartilage reflect disease severity?

OBJECTIVE

Cartilage degeneration in osteoarthritis (OA) leads to release of potential danger signals. The aim of our study was to profile OA cartilage for the Toll-like receptor (TLR) danger signal receptors.

METHODS

Osteochondral cylinders from total knee replacements were graded using OA Research Society International score and stained for proteoglycans, collagenase-cleaved type II collagen, and TLR 1-10, which were analyzed histomorphometrically.

RESULTS

Grade 1 OA lesions contained 22%-55% TLR 1-9-positive cells in the surface zone, depending on the TLR type. In Grade 2 TLR, immunoreactivity was 60%-100% (p < 0.01) and it was even higher in Grades 3 and 4 (p < 0.01 vs Grade 1). TLR-positive cells in Grade 1 middle zone were low, 0-19.9%, but were 5.1%-32.7% in Grade 2 (p < 0.01) and 34%-83% in Grades 3-4 samples (p < 0.001). TLR values in Grade 5 were low (14.3%-28.7%; p < 0.001). In Grades 3-4 OA, cartilage matrix stained strongly for TLR. In Grade 1, COL2-3/4M was restricted to chondrocytes, but was increasingly seen in matrix upon progress of OA to Grade 4, and then declined.

CONCLUSION

Cells in the gliding surface zone are fully equipped with TLR in mild OA. Their proportion increases and extends to the middle or even the deep zone, reflecting OA progression. COL2A-3/4M staining suggests Endo180-mediated intake for intralysosomal degradation by cathepsins in Grade 1, but in higher grades this chondrocyte-mediated clearance fails and the matrix demonstrates extensive collagenase-induced damage. Detached and/or partially degraded matrix components can then act as endogenous danger signals (damage-associated molecular patterns or DAMP) and stimulate increasingly TLR-equipped chondrocytes to inflammation. At the peak inflammatory response, soluble TLR may exert negative feedback, explaining in part the low TLR levels in Grade 5 OA.

Brief report: first identification of H₄ histamine receptor in healthy salivary glands and in focal sialadenitis in Sjögren's syndrome

OBJECTIVE

The conventional H(1) and H(2) histamine receptors have >10,000-fold lower avidity for histamine than H(4) histamine receptor, which has been implicated in autoimmune diseases. This study was undertaken to compare H(4) histamine receptor levels in the salivary glands (SGs) of healthy controls with those in the SGs of patients with primary Sjögren's syndrome (SS).

METHODS

H(4) histamine receptor messenger RNA (mRNA) was analyzed using real-time quantitative polymerase chain reaction, and the receptor protein was examined using immunostaining. Effects of the H(4) histamine receptor agonist ST-1006 on cytokine synthesis by human SG (HSG) cells were analyzed using xMAP technology and enzyme-linked immunosorbent assay.

RESULTS

Healthy SGs contained H(4) histamine receptor mRNA. The receptor protein was localized to the acinar and ductal epithelial cells. H(4) histamine receptor agonist stimulated HSG cells to produce the cytokines interleukin-8 and vascular endothelial growth factor. SS patients had low H(4) histamine receptor levels.

CONCLUSION

H(1) and H(2) histamine receptor antagonists are not effective in the treatment of autoimmune diseases. However, such antagonists do not affect the newly discovered H(4) histamine receptor. Dendritic cells and lymphocytes are nonprofessional histamine-producing cells, which produce histamine at 100-1,000-fold lower rates than mast cells do. Saliva contains only 0.31-12.4 ng/ml histamine, which is too low to stimulate H(1) or H(2) histamine receptor, but stimulates H(4) histamine receptor half maximally. Our findings show that H(4) histamine receptor is strongly expressed in tubuloacinar SG cells, which emphasizes the role of these cells in the pathogenesis of SS.

Basement membrane collagen type IV expression by human mesenchymal stem cells during adipogenic differentiation

During adipogenic differentiation human mesenchymal stem cells (hMSC) produce collagen type IV. In immunofluorescence staining differentiating hMSCs started to express collagen type IV when Oil Red O-positive fat droplets appeared intracellularly. Quantitative real time-polymerase chain reaction confirmed progressive increase of collagen type IV α1 and α2 mRNA levels over time, 18.6- and 12.2-fold by day 28, respectively, whereas the copy numbers of α3–α6 mRNAs remained rather stable and low. Type IV collagen was in confocal laser scanning microscopy seen around adipocytes, where also laminins and nidogen were found, suggesting pericellular deposition of all key components of the fully developed basement membrane. Immunofluorescence staining of matrix metalloproteinase-2 (MMP-2, 72 kD type IV collagenase, gelatinase A) and MMP-9 (92 kD type IV collagenase, gelatinase B) disclosed only faint staining of MSCs, but MMP-9 was strongly induced during adipogenesis, whereas MSC supernatants disclosed in zymography pro-MMP-2 and faint pro-MMP-9 bands, which increased over time, with partial conversion of pro-MMP-2 to its active 62 kD form. Differentiation was associated with increasing membrane type 1-MMP/MMP-14 and tissue inhibitor of metalloproteinase-2 (TIMP-2) staining, which may enable participation of type IV collagenases in basement membrane remodelling via ternary MT1-MMP/TIMP-2/MMP-2 or −9 complexes, focalizing the fully active enzyme to the cell surface. MMP-9, which increased more in immunofluorescence staining, was perhaps preferentially bound to cell surface and/or remodelling adipocyte basement membrane. These results suggest that upon MSC-adipocyte differentiation collagen type IV synthesis and remodelling become necessary when intracellular accumulation of fat necessitates a dynamically supporting and instructive, partly denatured adipogenic pericellular type IV collagen scaffold.

Role and regulation of VEGF and its receptors 1 and 2 in the aseptic loosening of total hip implants

It was hypothesized that vascular endothelial growth factor (VEGF) in fibroblasts participates in aseptic loosening of total hip replacement (THR) implants. Therefore, osteoarthritic (OA) samples (n = 11) were compared with synovial membrane-like interface tissues from revision THR (n = 10). VEGF-A and its receptors were stained using streptavidin-immunoperoxidase method. Their regulation by hypoxia and cytokines were studied in cultured fibroblasts using quantitative real-time polymerase chain reaction (qRT-PCR). VEGFR1(+) lining cells (p < 0.01), stromal fibroblast-like cells (p = 0.001) and stromal macrophage-like cells (p < 0.05) were more numerous in rTHR than in OA. As to VEGFR2(+), only stromal fibroblast-like cells in rTHR outnumbered those found in OA (p < 0.05). VEGFRs in synovial fibroblasts were not affected by hypoxia, but VEGF increased 2.4-fold (p < 0.05). Interleukin-4 up-regulated VEGFR1 expression 23-fold. This is the first study to describe a difference between rTHR and OA in VEGF receptors, particularly VEGFR1. Hypoxia increased VEGF, but the VEGFR1 increase in the lining and stroma is probably IL-4 driven, in accordance with the M2-type macrophage dominance in interface tissues. VEGF/VEGFR system is also affected by hypoxia and may play a role in angiogenesis and bone pathology in aseptic loosening of total hip implants.

Bone regeneration and stem cells

This invited review covers research areas of central importance for orthopaedic and maxillofacial bone tissue repair, including normal fracture healing and healing problems, biomaterial scaffolds for tissue engineering, mesenchymal and foetal stem cells, effects of sex steroids on mesenchymal stem cells, use of platelet-rich plasma for tissue repair, osteogenesis and its molecular markers. A variety of cells in addition to stem cells, as well as advances in materials science to meet specific requirements for bone and soft tissue regeneration by addition of bioactive molecules, are discussed.

BMPs in periprosthetic tissues around aseptically loosened total hip implants

BACKGROUND AND PURPOSE

Primary and dynamically maintained periprosthetic bone formation is essential for osseointegration of hip implants to host bone. Bone morphogenetic proteins (BMPs) play a role in osteoinductive bone formation. We hypothesized that there is an increased local synthesis of BMPs in the synovial membrane-like interface around aseptically loosened total hip replacement (THR) implants, as body attempts to generate or maintain implant fixation.

PATIENTS AND METHODS

We compared synovial membrane-like interface tissue from revised total hip replacements (rTHR, n = 9) to osteoarthritic control synovial membrane samples (OA, n = 11. Avidin-biotin-peroxidase complex staining and grading of BMP-2, BMP-4, BMP-6, and BMP-7 was done. Immunofluorescence staining was used to study BMP proteins produced by mesenchymal stromal/stem cells (MSCs) and osteoblasts.

RESULTS AND INTERPRETATION

All BMPs studied were present in the synovial lining or lining-like layer, fibroblast-like stromal cells, interstitial macrophage-like cells, and endothelial cells. In OA and rTHR samples, BMP-6 positivity in cells, inducible by the proinflammatory cytokines tumor necrosis factor-alpha and interleukin-1beta, predominated over expression of other BMPs. Macrophage-like cells positive for BMP-4, inducible in macrophages by stimulation with particles, were more frequent around loosened implants than in control OA samples, but apparently not enough to prevent loosening. MSCs contained BMP-2, BMP-4, BMP-6, and BMP-7, but this staining diminished during osteogenesis, suggesting that BMPs are produced by progenitor cells in particular, probably for storage in the bone matrix.

Immigration check for neutrophils in RA lining: laminin alpha5 low expression regions act as exit points

OBJECTIVE

A correlation exists between the absence of alpha5-laminin and transit checkpoint fenestrations in vascular basement membranes. We hypothesized that similar laminin alpha5 low expression regions might exist in synovial lining, which, although lacking basement membrane, contains all basement membrane components in its interstitial matrix.

METHODS

Laminin alpha4 and alpha5 chains and lactoferrin were stained using immunofluorescence and cathepsin G and neutrophil elastase using immunoperoxidase. Quantitative real-time polymerase chain reaction (qRT-PCR) was used to measure laminin alpha4 and alpha5 mRNA copy numbers in cultured synovial fibroblasts, without/with tumour necrosis factor-alpha (TNFalpha) and interleukin-1beta (IL-1beta).

RESULTS

Laminin alpha4 and alpha5 chains were found in the intercellular matrix in synovial lining samples of trauma and revision total hip replacements. Laminin alpha5 was weaker in osteoarthritis (OA) and rheumatoid arthritis (RA), and RA synovial lining also contained local low expression areas. Double staining disclosed convergence of lactoferrin-degranulating neutrophils towards these laminin alpha5 low expression regions. In cultured OA synovial fibroblasts, laminin alpha5 mRNA decreased (p < 0.05) at 1 ng/mL TNFalpha and was not found at all in cultured resting or cytokine-stimulated RA fibroblasts. Degranulation of cathepsin G and neutrophil elastase was seen in neutrophils passing through blood vessels or synovial lining.

CONCLUSIONS

Migrating neutrophils in RA seem to use laminin alpha5 chain low expression regions to exit synovial tissue to enter synovial fluid. Transmigrating neutrophils remodel the intercellular matrix by releasing their proteolytic granular contents to enhance these low expression checkpoints and/or to produce chemotactic stimuli. In RA fibroblasts this is facilitated by cytokine-mediated down-regulation or lack of laminin alpha5 synthesis.

Toll-like receptors and aseptic loosening of hip endoprosthesis-a potential to respond against danger signals?

Bacterial remnants and subclinical biofilms residing on prosthesis surfaces have been speculated to play a role in hip implant loosening by opsonizing otherwise relatively inert wear particles. The innate immune system recognizes these microbial pathogen-associated molecular patterns (PAMPs) using Toll-like receptors (TLRs). Our objective was to evaluate the possible presence of TLRs in aseptic synovial membrane-like interface tissue. Bacterial culture-negative, aseptic (n = 4) periprosthetic synovial membrane-like tissue was compared to osteoarthritis synovial membrane (n = 5) for the presence of cells positive for all known human functional TLRs, stained using specific antibodies by immunohistochemistry, and evaluated using morphometry. In comparison to osteoarthtritic synovium, the number of TLR-positive cells was found to be increased in the aseptic setting, reflecting the considerable macrophage infiltration to the tissues investigated. Thus aseptic periprosthetic tissue seems to be very reactive to PAMPs. It has been recently recognized that TLR do not only respond to traditional PAMPs, but also to endogenous alarmings or danger signals released from necrotic and activated cells. Alarming-TLR interaction in the periprosthetic tissue might be a novel mechanism of aseptic loosening of endoprosthesis.

Adhesion, spreading and osteogenic differentiation of mesenchymal stem cells cultured on micropatterned amorphous diamond, titanium, tantalum and chromium coatings on silicon

It was hypothesized that human mesenchymal stromal cell (hMSC) can be guided by patterned and plain amorphous diamond (AD), titanium (Ti), tantalum (Ta) and chromium (Cr) coatings, produced on silicon wafer using physical vapour deposition and photolithography. At 7.5 h hMSCs density was 3.0-3.5 x higher (P < 0.0003, except Ti) and cells were smaller (68 vs. 102 microm, P 0.000006-0.02) on patterns than on silicon background. HMSC-covered surface of the background silicon was lower on Ti than AD patterns (P = 0.015), but at 5 days this had reversed (P = 0.006). At 7.5 h focal vinculin adhesions and actin cytoskeleton were outgoing from pattern edges so cells assumed geometric square shapes. Patterns allowed induced osteogenesis, but less effectively than plain surfaces, except for AD, which could be used to avoid osseointegration. All these biomaterial patterns exert direct early, intermediate and late guidance on hMSCs and osteogenic differentiation, but indirect interactions exist with cells on silicon background.

Intracrine androgenic apparatus in human bone marrow stromal cells

It was suggested that human mesenchymal stromal cells might contain an intracrine enzyme machinery potentially able to synthesize the cell’s own supply of dihydrotestosterone (DHT) from dehydroepiandrosterone (DHEA) pro-hormone produced in the adrenal cortex in the reticular zone, which is unique to primates. Indeed, 3β-hydroxysteroid dehydrogenase (3β-HSD) and 5α-reductase enzyme proteins were expressed in resting mesenchymal stromal cells (MSCs) in vitro. However, the ‘bridging’ enzymes 17β-HSDs, catalysing interconversion between 17β-ketosteroids and 17β-hydroxysteroids, were not found in resting MSCs, but 17β-HSD enzyme protein was induced in a dose-dependent manner by DHEA. Quantitative real-time polymerase chain reactions disclosed that this was mainly due to induction of the isoform 5 catalysing this reaction in ‘forward’, androgen-bound direction (P < 0.01). This work demonstrates that the MSCs have an intracrine machinery to convert DHEA to DHT if and when challenged by DHEA. DHEA as substrate exerts a positive, feed-forward up-regulation on the 17β-hydroxy steroid dehydrogenase-5, which may imply that DHEA-DHT tailor-making in MSCs is subjected to chronobiological regulation.

Type IV collagen alpha-chain composition in synovial lining from trauma patients and patients with rheumatoid arthritis

OBJECTIVE

Normal synovial lining is composed of macrophage-like type A and fibroblast-like type B lining cells. This sheet-like structure lacks a basement membrane, but its intercellular substance contains some basement membrane components, including type IV collagen. We undertook this study to determine the alpha-chain composition of type IV collagen in normal and arthritic synovial lining, using monoclonal alpha-chain antibodies.

METHODS

Samples were analyzed using avidin-biotin-peroxidase complex staining for the presence of collagen alpha1/2(IV), alpha3(IV), alpha4(IV), alpha5(IV), alpha6(IV), matrix metalloproteinase 2 (MMP-2), and MMP-9, and the enzyme activity was detected using gelatin zymography. Double immunofluorescence was performed for type IV collagen/MMP-9 and type IV collagen/CD68. Synovial fibroblasts were studied using quantitative reverse transcriptase-polymerase chain reaction.

RESULTS

In mildly inflamed synovium from 5 trauma patients, alpha1/2(IV) chains were strongly stained, but alpha5(IV) and alpha6(IV) chains were weakly stained. Coding messenger RNA was shown in cultured synovial fibroblasts. Basement membranes of blood vessels contained all alpha(IV) chains and served as useful positive sample controls. In the synovial lining from 5 patients with rheumatoid arthritis (RA), all alpha-chains were absent/very weakly stained. This was coupled with numerous type A lining cells containing MMP-9 (type IV collagenase), also found in synovial fluid.

CONCLUSION

Synovial lining has a unique and very limited alpha-chain composition, different from that of the vascular basement membrane, which contains all alpha-chains. This special composition and lack of nidogen are probably of relevance for the bidirectional translining diffusion. Such tentative alpha-chain-dependent adhesive and transport-regulating properties seem to be deranged in RA, probably in part due to type IV collagenases produced in the lining and/or released by transmigrating or synovial fluid neutrophils.

Human osteoblasts produce cathepsin K

Healthy bone is a rigid yet living tissue that undergoes continuous remodeling. Osteoclasts resorb bone in the remodeling cycle. They secrete H(+)-ions and proteinases to dissolve bone mineral and degrade organic bone matrix, respectively. One of the main collagenolytic proteinase in osteoclasts is cathepsin K, a member of papain family cysteine proteinases. Recently, it has been shown that osteoblasts may contribute to organic matrix remodeling. We therefore investigated their ability to produce cathepsin K for this action. Trabecular bone samples were collected from patients operated due to a fracture of the femoral neck. Part of the bone was decalcified and the rest was used for cell isolation. Sections from the decalcified bone were immunostained with antibodies against cathepsin K. Isolated cells were characterized for their ability to form mineralized matrix and subsequently analyzed for their cathepsin K production by Western blotting and quantitative RT-PCR. Osteoblasts, bone lining cells and some osteocytes in situ showed cathepsin K immunoreactivity and osteoblast-like cells in vitro produced cathepsin K mRNA and released both 42 kDa pro- and 27 kDa processed cathepsin K to culture media. Osteoblastic cathepsin K may thus contribute to collagenous matrix maintenance and recycling of improperly processed collagen I. Whether osteoblastic cathepsin K synthesis has consequences in diseases characterized by abnormal bone matrix turnover remains to be investigated.

Screening for celiac disease in Down’s syndrome patients revealed cases of subtotal villous atrophy without typical for celiFac disease HLA-DQ and tissue transglutaminase antibodies

AIM: To investigate the prevalence of celiac disease (CD) as well as CD marker antibodies and susceptibility HLA-DQ haplotypes in 134 karyotyped Down’s syndrome (DS) patients.

METHODS: Immunoglobulin A (IgA) and G (IgG) type anti-gliadin antibodies (AGA), IgA type anti-tissue transglutaminase (tTG) antibodies (anti-tTG) with antigen of guinea pig and human source were determined by enzyme-linked immunosorbent assay and endomysium antibodies (EMA) by indirect immunofluoresence test. HLA-DQA1*0501/DQB1*0201 (DQ2) was revealed by polymerase chain reaction. Celiac disease was diagnosed by revised ESPGHAN criteria.

RESULTS: 41 % of DS patients had AGA, 6.0 % IgA anti-tTG with guinea pig antigen, and 3.0 % IgA EMA (all positive for anti-tTG with human tTG). Subtotal villous atrophy was found in 5 out of 9 DS patients who had agreed to small bowel biopsy. One of them had DQA1*0501/DQB1*0201 and anti-tTG and EMA i.e. typical for CD markers (this case also fulfilled the ESPGHAN diagnostic criteria), but other four lacked these markers. Three non-biopsied DS patients had also most probably CD because DQA1*0501/DQB1*0201 and IgA anti-tTG (EMA) were detected. Thus, the prevalence of CD among our DS patients population is 3.0 % (95 % of confidence interval [CI]: 0.1-5.9 %).

CONCLUSION: We confirm the increased frequency of CD among DS patients. In addition, we have revealed a subgroup of patients with subtotal villous atrophy but without characteristic for CD immunological and genetic markers. Whether these cases represent CD (with atypical immunopathogenesis) or some other immune enteropathy, requires further investigations.

A novel metalloprotease from Vipera lebetina venom induces human endothelial cell apoptosis

A novel endothelial cell apoptosis inducing metalloprotease (VLAIP) was found in the snake venom of Vipera lebetina. This metalloprotease is a heterodimeric glycoprotein with molecular mass of about 106 kDa. The protease hydrolyzes azocasein, fibrinogen and oxidized insulin B-chain. The enzyme readily hydrolyzes the Aalpha-chain and more slowly Bbeta-chain of fibrinogen. VLAIP does not cleave fibrin. The complete amino acid sequences of the two different monomers of VLAIP are deduced from the nucleotide sequences of cDNAs encoding these proteins. The full-length cDNA sequences of the VLAIP-A and VLAIP-B encode open reading frames of 616 and 614 amino acids that include signal peptide, propeptide and mature metalloproteinase with disintegrin-like and cysteine-rich domains. VLAIP belongs to the metalloprotease/disintegrin family of reprolysins and has high identity with the proteins that induce apoptosis of endothelial cells. Treatment of HUVEC cells with VLAIP induces changes in the attachment of cells to the substrate and causes cell death. We demonstrated that VLAIP inhibits endothelial cell adhesion to extracellular matrix proteins: fibrinogen, fibronectin, vitronectin, collagen I, and collagen IV. The induction of apoptosis by VLAIP was shown by means of a typical DNA fragmentation pattern of apoptotic cells as well as by monitoring phosphatidylserine externalization using annexin V-FITC staining and flow cytometric analysis.

Cholecystokinin2 receptor-deficient mice display altered function of brain dopaminergic system

RATIONALE

Cholecystokinin (CCK) has been shown to coexist and interact with dopamine in the regulation of behaviour. Two different CCK receptors (CCK1 and CCK2) have an opposite influence on the activity of dopamine neurons. Stimulation of CCK2 receptors decreases the release of dopamine and that receptor could mediate the neuroleptic-like effect of CCK.

OBJECTIVE

To investigate the activity of the dopaminergic system in pharmacological experiments on CCK2 receptor (CCK2R)-deficient mice.

METHODS

We used age- and sex-matched littermates in all our experiments. To evaluate the behavioural differences, we performed the rotarod test and measured the locomotor activity of animals using computer-connected photoelectric motility boxes. Amphetamine and apomorphine, two dopaminergic drugs with different pharmacodynamic properties, were used to influence the activity of the dopaminergic system in the brain. Neurochemical differences related to the different genotype were analysed by means of high-performance liquid chromatography and radioligand binding studies.

RESULTS

Motor co-ordination was significantly impaired in the rotarod test of CCK2R receptor-deficient mice. Moreover, the locomotor activity of heterozygous (+/-) and homozygous (-/-) CCK2R receptor-deficient mice was somewhat reduced. A low dose of apomorphine (0.1 mg/kg), an unselective agonist of dopamine receptors, suppressed locomotor activity significantly more in homozygous (-/-) and heterozygous (+/-) mutant mice than in their wild-type (+/+) littermates. Amphetamine (3-6 mg/kg), increasing release of dopamine from the presynaptic terminals, caused a dose-dependent motor stimulation in wild-type (+/+) mice. In heterozygous (+/-) and homozygous (-/-) mice, a lower dose of amphetamine (3 mg/kg) did not alter the locomotor activity, whereas the higher dose of (6 mg/kg) induced a significantly stronger increase in locomotor activity in homozygous (-/-) mice than in their heterozygous (+/-) and wild-type (+/+) littermates. Despite the changes in the action of apomorphine and amphetamine in homozygous (-/-) mice, we did not find any significant differences in the concentration of dopamine and their metabolites in the striatum or cortex. However, the density of dopamine D2 receptors was significantly increased in the striatum of homozygous (-/-) animals compared with wild-type (+/+) mice.

CONCLUSIONS

The targeted mutation of the CCK2 receptor gene induced gene dose-dependent changes in the activity of the dopaminergic system. The sensitivity of presynaptic dopamine receptors was increased in heterozygous (+/-) and homozygous (-/-) animals, whereas the increase in sensitivity of postsynaptic dopamine receptors was apparent only in homozygous (-/-) mice.