Continuous cyclic mechanical tension increases ank expression in endplate chondrocytes through the TGF-β1 and p38 pathway

Synovial Membrane Is a Major Producer of Extracellular Inorganic Pyrophosphate in Response to Hypoxia

Calcium pyrophosphate dehydrate (CPPD) crystals are found in the synovial fluid of patients with articular chondrocalcinosis or sometimes with osteoarthritis. In inflammatory conditions, the synovial membrane (SM) is subjected to transient hypoxia, especially during movement. CPPD formation is supported by an increase in extracellular inorganic pyrophosphate (ePPi) levels, which are mainly controlled by the transporter Ank and ectonucleotide pyrophosphatase/phosphodiesterase 1 (ENPP1). We demonstrated previously that transforming growth factor (TGF)-β1 increased ePPi production by inducing Ank and Enpp1 expression in chondrocytes. As the TGF-β1 level raises in synovial fluid under hypoxic conditions, we investigated whether hypoxia may transform SM as a major source of ePPi production. Synovial fibroblasts and SM explants were exposed to 10 ng/mL of TGF-β1 in normoxic or hypoxic (5% O2) culture conditions. Ank and Enpp1 expression were assessed by quantitative PCR, Western blot and immunohistochemistry. ePPi was quantified in culture supernatants. RNA silencing was used to define the respective roles of Ank and Enpp1 in TGF-β1-induced ePPi generation. The molecular mechanisms involved in hypoxia were investigated using an Ank promoter reporter plasmid for transactivation studies, as well as gene overexpression and RNA silencing, the respective role of hypoxia-induced factor (HIF)-1 and HIF-2. Our results showed that TGF-β1 increased Ank, Enpp1, and therefore ePPi production in synovial fibroblasts and SM explants. Ank was the major contributor in ePPi production compared to ENPP1. Hypoxia increased ePPi levels on its own and enhanced the stimulating effect of TGF-β1. Hypoxic conditions enhanced Ank promoter transactivation in an HIF-1-dependent/HIF-2-independent fashion. We demonstrated that under hypoxia, SM is an important contributor to ePPi production in the joint through the induction of Enpp1 and Ank. These findings are of interest as a rationale for the beneficial effect of anti-inflammatory drugs on SM in crystal depositions.

Impaired breakdown of Herwig's epithelial root sheath disturbs tooth root development

BACKGROUND

Wnt/β-catenin signaling plays a variety of roles in both the dental epithelium and mesenchyme at most stages of tooth development. In this study, we verified the roles of Hertwig's epithelial root sheath (HERS) breakdown in tooth root development. This breakdown results in formation of epithelial cell rests of Malassez (ERM).

RESULTS

Following induction of β-catenin stabilization in the epithelium of developing tooth at the moment of HERS breakdown, HERS failed to break down for ERM formation. HERS with stabilized β-catenin was altered into a multicellular layer enveloping elongated root dentin with higher expression of junctional proteins such as Zo-1 and E-cadherin. Importantly, this impairment of HERS breakdown led to arrest of further root elongation. In addition, the portion of root dentin enveloped by the undissociated HERS remained in a hypomineralized state. The odontoblasts showed ectopically higher expression of pyrophosphate regulators including Ank and Npp1, whereas Tnap expression was unchanged.

CONCLUSIONS

Our data suggest that Wnt/β-catenin signaling is decreased in HERS for ERM formation during root development. Furthermore, ERM formation is important for further elongation and dentin mineralization of the tooth roots. These findings may provide new insight to understand the contribution of ERM to root formation.

Intermittent cyclic mechanical compression promotes endplate chondrocytes degeneration by disturbing Nrf2/PINK1 signaling pathway-dependent mitophagy

An abnormal mechanical load is a pivotal inducer of endplate cartilage degeneration, which subsequently promotes intervertebral disc degeneration. Our previous study indicated that intermittent cyclic mechanical compression (ICMC) promotes endplate chondrocyte degeneration, but the mechanism underlying this effect is unclear. In this study, we investigated PTEN-induced kinase 1(PINK1) dependent mitophagy during ICMC-induced endplate chondrocyte degeneration. Furthermore, we determined whether NF-E2-related factor 2 (Nrf2) activation correlated with PINK1-dependent mitophagy regulation and increased oxidation resistance of endplate chondrocytes under ICMC application. First, we generated a mechanical compression-induced endplate chondrocyte degeneration model in vitro and in vivo. ICMC was found to promote endplate chondrocyte extracellular matrix degradation. PINK1-mediated mitophagy was suppressed in the ICMC-stimulated endplate chondrocytes, while increased mitochondrial reactive oxygen species generation suggested that mitophagy is involved in the protective effect of mechanical strain on endplate chondrocytes. Moreover, Nrf2 expression, interaction with Kelch-like ECH-associated protein (Keap1), and nuclear translocation were inhibited by ICMC. Nrf2 overexpression inhibited reactive oxygen species production and reversed ICMC-induced endplate chondrocyte degeneration. Transfection with PINK1 shRNA abolished this effect and partially blocked Nrf2-induced mitophagy. Our findings suggested that ICMC could inhibit the Nrf2/PINK1 signaling pathway to reduce the mitophagy levels which significantly promote oxidative stress and thereby endplate chondrocyte degeneration. Therapeutic regulation of the Nrf2/PINK1 signaling pathway may be an efficient anabolic strategy for inhibiting this process.

Mechanism of the Mitogen-Activated Protein Kinases/Mammalian Target of Rapamycin Pathway in the Process of Cartilage Endplate Stem Cell Degeneration Induced by Tension Load

STUDY DESIGN

Basic Research.

OBJECTIVE

Intervertebral disc degeneration (IVDD) is caused by the cartilage endplate (CEP). Cartilage endplate stem cell (CESC) is involved in the recovery of CEP degeneration. Tension load (TL) contributes a lot to the initiation and progression of IVDD. This study aims to investigate the regulatory mechanism of the Mitogen-activated protein kinases/Mammalian target of rapamycin (MAPK/mTOR) pathway during TL-induced CESC degeneration.

METHODS

CESCs were isolated from New Zealand big-eared white female rabbits (6 months old). FX-4000T cell stress loading system was applied to establish a TL-induced degeneration model of CESCs. Western blotting was used to detect the level of mTOR pathway-related proteins and autophagy markers LC3-Ⅱ, Beclin-1, and p62 in degenerative CESCs. The expression of MAPK pathway-related proteins JNK and extracellular signal-regulated kinases (ERK) in degenerated CESCs was inhibited by cell transfection to explore whether JNK and ERK play a regulatory role in TL-induced autophagy in CESCs.

RESULTS

In the CESC degeneration model, the mTOR pathway was activated. After inhibition of mTOR, the autophagy level of CESCs was increased, and the degeneration of CESCs was alleviated. The MAPK pathway was also activated in the CESC degeneration model. Inhibition of JNK expression may alleviate TL-induced CEP degeneration by inhibiting Raptor phosphorylation and activating autophagy. Inhibition of ERK expression may alleviate TL-induced CEP degeneration by inhibiting mTOR phosphorylation and activating autophagy.

CONCLUSION

Inhibition of JNK and ERK in the MAPK signaling family alleviated TL-induced CESC degeneration by inhibiting the phosphorylation of Raptor and mTOR in the mTOR pathway.

YAP1 controls degeneration of human cartilage chondrocytes in response to mechanical tension

Disc herniation is a kind of disease caused by degenerative discs, which is common in the elderly, bringing substantial financial burden to families and society. Mechanical tension has a vital effect on the maintenance of cartilage function, however, the molecular mechanism by which mechanical tension causes degenerative discs to remain unclear. This study was the first to reveal Yes-associated protein 1(YAP1) is a key regulator in mechanical tension-mediated degenerative discs. Activation of YAP1 may be a valuable strategy to delays the degeneration of human cartilage chondrocytes. We found that YAP1 expression was significantly decreased in degenerative human endplate cartilage and tissue with the strength and time of mechanical stimulation, but the cell cycle distribution was significantly changed under the 10% cyclic mechanical tension(CMT). Besides, the degeneration of endplate cartilage can be delayed by activating the expression level of YAP1 in vitro and it has also been verified in the cartilage endplate tissue in vitro. Furthermore, We found that YAP1 and TEAD1 overexpression increased the activity of the ACAN or COL2A1 promoter to enhance the transcriptional activity of human chondrocyte collagen. The CMT activates the classic Hippo signaling pathway of YAP1, and piezo1 may regulate YAP1 expression through the Hippo signaling pathway. In conclusion, these results suggest the novel mechanism of YAP contributes to delaying the degeneration of endplate cartilage and targeting YAP in combination with Piezo1 is a potential therapeutic approach for the treatment of endplate cartilage degeneration.

Efficient TGF-β1 Delivery to Articular Chondrocytes In Vitro Using Agro-Based Liposomes

The low efficiency in transfecting rat- and human-derived chondrocytes have been hampering developments in the field of cartilage biology. Transforming growth factor (TGF)-β1 has shown positive effects on chondrocytes, but its applications remain limited due to its short half-life, low stability and poor penetration into cartilage. Naturally derived liposomes have been shown to be promising delivery nanosystems due to their similarities with biological membranes. Here, we used agro-based rapeseed liposomes, which contains a high level of mono- and poly-unsaturated fatty acids, to efficiently deliver encapsulated TGF-β1 to rat chondrocytes. Results showed that TGF-β1 encapsulated in nano-sized rapeseed liposomes were safe for chondrocytes and did not induce any alterations of their phenotype. Furthermore, the controlled release of TGF-β1 from liposomes produced an improved response in chondrocytes, even at low doses. Altogether, these outcomes demonstrate that agro-based nanoliposomes are promising drug carriers.

Circ_0022382 ameliorated intervertebral disc degeneration by regulating TGF-β3 expression through sponge adsorption of miR-4726-5p

Circular RNAs (circRNAs) participate in the progression of many diseases, but knowledge on the role of circRNAs in intervertebral disc degeneration (IDD) is limited. In this study, we discovered the characteristics of a new circRNA (circ_0022382) in human endplate chondrocytes. Currently, real-time quantitative polymerase chain reaction (RT-qPCR) showed that the relative expression level of circ_0022382 was significantly lower under intermittent cyclic tension stimulation than in the control group. circ_0022382, miR-4726-5p and Transforming growth factor 3 (TGF-β3) were evaluated by RT-qPCR, Western Blot and immunofluorescence assay. Additionally, the role and mechanism of circ_0022382 in vivo were also consistent in the rat model. Furthermore, Intermittent cyclic mechanical tension can cause degeneration of endplate chondrocytes. The tension-sensitive circRNA_0022382 was decreased, and we found that circRNA_0022382 promoted morphology of endplate chondrocytes by sponge-binding miR-4726-5p down-regulation of target gene the TGF-β3 expression, thereby alleviating IDD. In a rat model of acupuncture, intervertebral disc injection of circ_0022382 relieved the progression of IDD in vivo. In conclusion, the circ_0022382/miR-4726-5p/TGF-β3 axis plays a key role in the anabolism and catabolism of the endplate chondrocyte extracellular matrix (ECM). It is suggested that circ_0022382 may provide a new approach for the prevention and treatment of IDD.

The treatment of intervertebral disc degeneration using Traditional Chinese Medicine

ETHNOPHARMACOLOGICAL RELEVANCE

Intervertebral disc degeneration (IDD) is one of the most common causes of chronic low back pain that spending a lot of workforces and financial resources, seriously affecting human physical and mental health. Clinically used drug treatments and surgical treatments cannot fundamentally relieve the disease and have a risk of recurrence. Traditional Chinese Medicine (TCM) has a history of more than a thousand years in the prevention and treatment of IDD. However, so far, there are few reviews on the treatment of IDD by TCM. Therefore, it is crucial and necessary to systematically mine the existing literature on the treatment of IDD with TCM. This paper strives to systematically describe the modern medicine and TCM theoretical research on IDD, progress in the treatment of IDD and focuses on the treatment of IDD by TCM, which would lay some theoretical foundation and provide new directions for future research.

MATERIALS AND METHODS

Information on clinical observations, animal experiments and relevant pharmacology data about the treatment of IDD were gathered from various sources including traditional Chinese books and Chinese Pharmacopoeia, scientific databases (Elsevier, PubMed, Science Direct, Baidu Scholar, CNKI, Spring Link, Web of Science) and from different professional websites.

RESULTS

This review mainly introduces the current research on the theoretical research on IDD, the combination principle of the TCM formula, and the underlying mechanism of the formula and active ingredients.

CONCLUSIONS

At present, domestic and foreign scholars have carried out a lot of research in different ways, such as the molecular mechanism and predisposing factors of IDD, which provides theoretical development and clinical practice significance for future research. TCM, as a multi-component and multi-targeted drug, can produce synergistic effects to exert its efficacy. Therefore, the development of TCM with more specific functions and practical data will not only become a significant trend in the world market but also has an irreplaceable role in the future treatment of IDD.

Curcumin prevents tension-induced endplate cartilage degeneration by enhancing autophagy

AIMS

Intermittent cyclic tension stimulation(ICMT) was shown to promote degeneration of endplate chondrocytes and induce autophagy. However, enhancing autophagy can alleviate degeneration partly. Studies have shown that curcumin can induce autophagy and protect chondrocytes, we speculated that regulation of autophagy by curcumin might be an effective method to improve the stress resistance of endplate cartilage. In this study, human cervical endplate cartilage specimens were collected, and expression of autophagy markers was detected and compared.

MAIN METHODS

Human cervical endplate chondrocytes were cultured to establish a tension-induced degeneration model, for which changes of functional metabolism and autophagy levels were detected under different tension loading conditions. Changes in functional metabolism of endplate chondrocytes were observed under high-intensity tension loading in the presence of inhibitors, inducers, and curcumin to regulate the autophagy level of cells. In addition, a rat model of lumbar instability was established to observe the degeneration of lumbar disc after curcumin administration.

KEY FINDINGS

Through a series of experiments, we found that low-intensity tension stimulation can maintain a stable phenotype of endplate chondrocytes, but high-intensity tension stimulation has a negative effect. Moreover, with increasing tension intensity, the degree of degeneration of endplate chondrocytes was gradually aggravated and the level of autophagy increased. Besides, curcumin upregulated autophagy, inhibited apoptosis, and reduced phenotype loss of endplate chondrocytes induced by high-intensity tension loading, thereby relieving intervertebral disc degeneration induced by mechanical imbalance.

SIGNIFICANCE

Curcumin mediated autophagy and enhanced the adaptability of endplate chondrocytes to high-intensity tension load, thereby relieving intervertebral disc degeneration.

circRNA_0058097 promotes tension-induced degeneration of endplate chondrocytes by regulating HDAC4 expression through sponge adsorption of miR-365a-5p

Excessive mechanical tension can lead to the degeneration of endplate chondrocytes. The presence of tension-sensitive circRNA_0058097 molecules has been detected in human endplate chondrocytes, where it was found to be a potential competing endogenous RNA. Indeed, inhibiting the expression of circRNA_0058097 effectively enhanced the stress resistance of endplate chondrocytes, suggesting that it may be an important trigger point for the degeneration of endplate cartilage. Through a series of experiments, we reveal that circRNA_0058097 can upregulate the expression of downstream target gene histone deacetylase 4 by sponge adsorption of miR-365a-5p, which promoted morphological changes of endplate chondrocytes, and increased extracellular matrix degradation and degeneration of endplate cartilage. Therefore, circRNA_0058097 may provide a new way to prevent and treat endplate cartilage degeneration.

TGF-β/SMAD signaling inhibits intermittent cyclic mechanical tension-induced degeneration of endplate chondrocytes by regulating the miR-455-5p/RUNX2 axis

A mechanical stimulation plays a pivotal role in maintaining normal cartilage function. Our objective was to reveal the mechanism of action of the tension-sensitive molecule miR-455-5p in the degeneration of endplate chondrocytes and to identify whether the transforming growth factor beta (TGF-β)/SMAD signaling pathway has a regulatory effect on it. The expression profiles of members of the TGF-β/SMAD pathway, miR-455-5p, and RUNX2 were determined by microRNA microarray analysis, reverse transcription quantitative polymerase chain reaction, luciferase reporter assay, and Western blot analysis. Intermittent cyclic mechanical tension (ICMT) induced the degeneration of endplate chondrocytes without affecting their viability. The tension-sensitive molecule miR-455-5p specifically bound to RUNX2, a gene involved in the degeneration of endplate chondrocytes. Activation of the TGF-β/SMAD signaling pathway upregulated miR-455-5p expression and thus inhibited RUNX2 levels. Therefore, the TGF-β/SMAD signaling pathway inhibits the ICMT-induced degeneration of endplate chondrocytes by regulating the miR-455-5p/RUNX2 axis.

Intermittent cyclic mechanical tension altered the microRNA expression profile of human cartilage endplate chondrocytes

Previous studies have identified the association between cartilage endplate (CEP) degeneration and abnormal mechanical loading. Several studies have reported that intermittent cyclic mechanical tension (ICMT) regulates CEP degeneration via various biological processes and signaling pathways. However, the functions of microRNAs in regulating the cellular responses of CEP chondrocytes to ICMT remain to be elucidated. The current study determined the differentially expressed microRNAs in human CEP chondrocytes exposed to ICMT using microarray analysis. A total 21 significantly upregulated and 62 downregulated miRNAs were identified compared with the control. The findings were subsequently partially validated by reverse transcription-quantitative polymerase chain reaction. Potential target genes of the significantly differentially expressed miRNAs were predicted using bioinformatics analysis and were used for Gene Ontology analysis and Kyoto Encyclopedia of Genes and Genomes pathway analysis. The present study revealed that the significantly differentially expressed microRNAs were involved in various signaling pathways and biological processes that are crucial to regulating the responses of CEP chondrocytes to ICMT. The current study provided a global view of microRNA expression in CEP chondrocytes under mechanical stimulation, suggesting that microRNAs are important for regulating the mechanical response of CEP chondrocytes. Additionally, it provided a novel insight into the association between mechanical stress and the establishment and progression of intervertebral disc degeneration.

Intermittent Cyclic Mechanical Tension Promotes Degeneration of Endplate Cartilage via the Nuclear Factor-κB Signaling Pathway: an in Vivo Study

OBJECTIVE

To establish a rabbit model for investigating the effects of intermittent cyclic mechanical tension (ICMT) on promoting degeneration of endplate cartilage.

METHODS

Forty New Zealand white rabbits were subjected to surgery and randomly divided into three equal groups as follows: control group (no treatment, n = 10), sham group (animals underwent a sham operation but were not subjected to mechanical tensile strain, n = 15) and loaded group (discs were subjected to 1.5 MPa external tensile loading by using an external loading device during the animals' daily activity, n = 15). Mechanical tensile strain was applied for 8 h/d. The animals were examined radiologically after 8 weeks treatment and then killed for removal of endplate cartilage tissue samples from their spines. Histological staining was performed to examine the morphology of endplate cartilage tissue. Multiple strategies were employed to examine degeneration of endplate cartilage and nuclear factor (NF)-κB signaling pathway activation.

RESULTS

After ICMT loading for 56 days, radiology revealed ossification, hyperosteogeny and stenosis in the intervertebral spaces. Examination of hematoxylin and eosin staining of sections of endplate cartilage showed significant damage as the load duration increased in the ICMT loading group. Expression of aggrecan (ACAN), type II collagen (COL-2A), SRY-related high mobility group-box gene 9 (SOX9) was down-regulated (FACAN = 21.515, P < 0.01; FCOL-2A = 6.670, P = 0.05; FSOX9 = 7.888, P < 0.05), whereas that of matrix metallopeptidase 13 (MMP13) was up-regulated (FMMP13 = 14.120, P < 0.01) after ICMT. Western blot and immunofluorescence revealed that expression of protein was consistent with gene expression results. Additionally, ICMT loading can lead to NF-κB signaling pathway activation as well as degeneration of endplate cartilage.

CONCLUSION

These experiments indicate that ICMT contributes to the activation of NF-κB signaling pathway in vivo and that the NF-κB signaling pathway further up-regulates MMP13, leading to degeneration of endplate cartilage.

Lectin-like, oxidized low-density lipoprotein receptor-1-deficient mice show resistance to age-related knee osteoarthritis

The lectin-like, oxidized low-density lipoprotein (ox-LDL) receptor-1 (LOX-1)/ox-LDL system contributes to atherosclerosis and may be involved in cartilage degeneration. The purpose of this study was to determine whether the LOX-1/ox-LDL system contributes to age-related osteoarthritis (OA) in vivo, using LOX-1 knockout (LOX-1 KO) mice. Knee cartilage from 6, 12, and 18-month old (n = 10/group) C57Bl/6 wild-type (WT) and LOX-1 KO mice was evaluated by determining the Osteoarthritis Research Society International (OARSI) score of Safranin-O stained samples. The prevalence of knee OA in both mouse strains was also investigated. Expression levels of LOX-1, ox-LDL, runt-related transcription factor-2 (Runx2), type-X collagen (COL X), and matrix metalloproteinase-13 (MMP-13) in the articular chondrocytes were analyzed immunohistologically. No significant difference was observed in the mean scores of WT (2.00±0.61) and LOX-1 KO mice (2.00±0.49) at 6 months of age (P=1.00, n=10). At 12 and 18 months of age, the mean scores of LOX-1 KO mice (3.75±0.93 and 5.50±0.78) were significantly lower than those of WT mice (5.25±1.14 and 9.00±1.01; P<0.001 in both cases; n=10). The prevalence of OA in LOX-1 KO mice was lower than that in WT mice at 12 and 18 months of age (40 vs 70%, 70 vs 90%, respectively; n=10). The expression levels of Runx2, COL X, and MMP-13 in articular chondrocytes significantly decreased in LOX-1 KO, mice compared with those in WT mice. The study indicated that the LOX-1/ox-LDL system in chondrocytes plays a role in the pathogenesis of age-related knee OA, which is potentially a target for preventing OA progression.

Intermittent cyclic mechanical tension promotes endplate cartilage degeneration via canonical Wnt signaling pathway and E-cadherin/β-catenin complex cross-talk

OBJECTIVE

This study aimed to investigate the role of the Wnt/β-catenin signaling pathway and E-cadherin/β-catenin complex in intermittent cyclic mechanical tension (ICMT)-induced endplate cartilage degeneration.

DESIGN

β-Catenin expression was measured in disc samples obtained from patients with disc degeneration and those with cervical vertebrae fracture or dislocation. Histological staining was performed to examine the disc tissue morphology and extracellular matrix after application of ICMT in vitro and in vivo. Multiple strategies were employed to examine activation of Wnt/β-catenin signaling after ICMT application in vivo and in vitro. Co-immunoprecipitation was performed to examine the interaction between E-cadherin and β-catenin. Pathway-specific inhibitors and an E-cadherin expression plasmid were used to regulate Wnt/β-catenin signaling and E-cadherin expression.

RESULTS

β-Catenin protein expression was elevated significantly, whereas cartilaginous genes were down-regulated in endplate cartilage samples obtained from patients with disc degeneration. ICMT loading led to Wnt/β-catenin signaling activation and the loss of the chondrogenic phenotype of endplate chondrocytes in both an in vivo rabbit model and in vitro endplate chondrocyte culture system. Inhibition of Wnt/β-catenin signaling suppressed the decrease in ICMT-induced cartilaginous gene expression. Furthermore, E-cadherin expression was inhibited by ICMT stimulation, resulting in a decrease in the interaction between E-cadherin and β-catenin proteins. Over-expression of E-cadherin rescued the cartilaginous gene expression by enhancing the interaction between E-cadherin and β-catenin proteins.

CONCLUSIONS

ICMT promotes endplate cartilage degeneration via activation of Wnt/β-catenin signaling and suppression of physical protein-protein interactions between E-cadherin and β-catenin.

Histochemistry in biology and medicine: a message from the citing journals

Especially in recent years, biomedical research has taken advantage of the progress in several disciplines, among which microscopy and histochemistry. To assess the influence of histochemistry in the biomedical field, the articles published during the period 2011-2015 have been selected from different databases and grouped by subject categories: as expected, biological and biomedical studies where histochemistry has been used as a major experimental approach include a wide of basic and applied researches on both humans and other animal or plant organisms. To better understand the impact of histochemical publications onto the different biological and medical disciplines, it was useful to look at the journals where the articles published in a multidisciplinary journal of histochemistry have been cited: it was observed that, in the five-years period considered, 20% only of the citations were in histochemical periodicals, the remaining ones being in journals of Cell &amp; Tissue biology,  general and experimental Medicine, Oncology, Biochemistry &amp; Molecular biology, Neurobiology, Anatomy &amp; Morphology, Pharmacology &amp; Toxicology, Reproductive biology, Veterinary sciences, Physiology, Endocrinology, Tissue engineering &amp; Biomaterials,  as well as in multidisciplinary journals.It is easy to foresee that also in the future the histochemical journals will be an attended forum for basic and applied scientists in the biomedical field. It will be crucial that these journals be open to an audience as varied as possible, publishing articles on the application of refined techniques to very different experimental models: this will stimulate non-histochemist scientists to approach histochemistry whose application horizon could expand to novel and possibly exclusive subjects.

Impact of Histochemistry on biomedical research: looking through the articles published in a long-established histochemical journal

Histochemistry provides the unique opportunity to detect single molecules in the very place where they exert their structural roles or functional activities: this makes it possible to correlate structural organization and function, and may be fruitfully exploited in countless biomedical research topics. Aiming to estimate the impact of histochemical articles in the biomedical field, the last few years citations of articles published in a long-established histochemical journal have been considered. This brief survey suggests that histochemical journals, especially the ones open to a large spectrum of research subjects, do represent an irreplaceable source of information not only for cell biologists, microscopists or anatomists, but also for biochemists, molecular biologists and biotechnologists.

Investigating conversion of endplate chondrocytes induced by intermittent cyclic mechanical unconfined compression in three-dimensional cultures

Mechanical stimulation is known to regulate the calcification of endplate chondrocytes. The Ank protein has a strong influence on anti-calcification by transports intracellular inorganic pyrophosphate (PPi) to the extracellular matrix. It is known that TGF-β1 is able to induce Ank gene expression and protect chondrocyte calcification. Intermittent cyclic mechanical tension (ICMT) could induce calcification of endplate chondrocytes by decrease the expression of Ank gene. In this study, we investigated the relation of intermittent cyclic mechanical unconfined compression (ICMC) and Ank gene expression. We found that ICMC decreased the Ank gene expression in the endplate chondrocytes, and there was an decreased in the TGF-β1 expression after ICMC stimulation. The Ank gene expression significantly increased when treated by transforming growth factor alpha 1 (TGF-β1) in a dose-dependent manner and decreased when treated by SB431542 (ALK inhibitor) in a dose-dependent manner. Our results implicate that ICMC-induced downregulation of Ank gene expression may be regulated by TGF-β1 in end-plate chondrocytes.

Histochemistry as an irreplaceable approach for investigating functional cytology and histology

In agreement with the evolution of histochemistry over the last fifty years and thanks to the impressive advancements in microscopy sciences, the application of cytochemical techniques to light and electron microscopy is more and more addressed to elucidate the functional characteristics of cells and tissue under different physiological, pathological or experimental conditions. Simultaneously, the mere description of composition and morphological features has become increasingly sporadic in the histochemical literature. Since basic research on cell functional organization is essential for understanding the mechanisms responsible for major biological processes such as differentiation or growth control in normal and tumor tissues, histochemical Journals will continue to play a pivotal role in the field of cell and tissue biology in all its structural and functional aspects.