Comparison of connective tissue components in the uterine ligaments between women with and without pelvic organ prolapse

AIM

Aim of the study was the comparison of the connective tissue components in the uterine ligaments between the women with and without pelvic organ prolapse.

METHODS

This study included 15 postmenopausal women without pelvic organ prolapse who underwent total abdominal hysterectomy and bilateral salpingo-oophorectomy for benign pathologies (control group) and 15 postmenopausal women who underwent vaginal hysterectomy because of pelvic organ prolapse (POP group). During the operation, samples for histological examination were taken from the cardinal and sacrouterine ligaments. The contents of collagen type I, collagen type III and elastin, and number and mitotic activity of fibroblasts in uterine ligaments were histopatholocially determined.

RESULTS

The collagen type I content for the POP group was significantly higher than that of the control group. Collagen type III content, elastin content, and number and mitotic activity of fibroblasts were not significantly different between the control and POP groups.

CONCLUSION

Collagen type I was found to be increased in the uterine ligaments of the POP group. The other connective tissue components did not differ between the two groups.

Structure, physiology, and biochemistry of collagens

Tendons and ligaments are connective tissues that guide motion, share loads, and transmit forces in a manner that is unique to each as well as the anatomical site and biomechanical stresses to which they are subjected. Collagens are the major molecular components of both tendons and ligaments. The hierarchical structure of tendon and its functional properties are determined by the collagens present, as well as their supramolecular organization. There are 28 different types of collagen that assemble into a variety of supramolecular structures. The assembly of specific supramolecular structures is dependent on the interaction with other matrix molecules as well as the cellular elements. Multiple suprastructural assemblies are integrated to form the functional tendon/ligament. This chapter begins with a discussion of collagen molecules. This is followed by a definition of the supramolecular structures assembled by different collagen types. The general principles involved in the assembly of collagen-containing suprastructures are presented focusing on the regulation of tendon collagen fibrillogenesis. Finally, site-specific differences are discussed. While generalizations can be made, differences exist between different tendons as well as between tendons and ligaments. Compositional differences will impact structure that in turn will determine functional differences. Elucidation of the unique physiology and pathophysiology of different tendons and ligaments will require an appreciation of the role compositional differences have on collagen suprastructural assembly, tissue organization, and function.

Estrogen-related genome-based expression profiling study of uterosacral ligaments in women with pelvic organ prolapse

INTRODUCTION AND HYPOTHESIS

The aim of the study was to identify the differential expression of estrogen-related genes that may be involved in the menopause and pelvic organ prolapse (POP) using microarray analysis.

METHODS

An age, parity, and menopausal status-matched case-control study with 12 POP patients and 5 non-POP patients was carried out. The study was conducted from January to December 2010 at Yonsei University, Severance Hospital. We examined microarray gene expression profiles in uterosacral ligaments (USLs) from POP and non-POP patients. Total RNA was extracted from USL samples to generate labeled cDNA, which was hybridized to microarrays and analyzed for the expression of 44,049 genes. We identified differentially expressed genes and performed functional clustering. After clustering, we focused on transcriptional response and signal transduction gene clusters, which are associated with estrogen, and then validated the changes of gene expression levels observed with the microarray analysis using quantitative polymerase chain reaction (qPCR).

RESULTS

The data from the microarray analysis using more than a 1.5-fold change with p value <0.05 resulted in 143 upregulated genes and 87 downregulated genes. Of 59 genes identified to be associated with signal transduction and transcription, 4 genes were chosen for qPCR that have been classified to be associated with estrogen. We found that estrogen receptor-related receptor-α (ERRα) was downregulated and that the expression of death-associated protein kinase 2 (DAPK 2), signal-transducing adaptor protein-2 (STAP-2), and interleukin (IL)-15 were upregulated.

CONCLUSIONS

We found four differentially expressed genes by microarray analysis that may account for the way in which changes in estrogen level affect POP pathophysiology.

Quantitative mapping of matrix content and distribution across the ligament-to-bone insertion

The interface between bone and connective tissues such as the Anterior Cruciate Ligament (ACL) constitutes a complex transition traversing multiple tissue regions, including non-calcified and calcified fibrocartilage, which integrates and enables load transfer between otherwise structurally and functionally distinct tissue types. The objective of this study was to investigate region-dependent changes in collagen, proteoglycan and mineral distribution, as well as collagen orientation, across the ligament-to-bone insertion site using Fourier transform infrared spectroscopic imaging (FTIR-I). Insertion site-related differences in matrix content were also evaluated by comparing tibial and femoral entheses. Both region- and site-related changes were observed. Collagen content was higher in the ligament and bone regions, while decreasing across the fibrocartilage interface. Moreover, interfacial collagen fibrils were aligned parallel to the ligament-bone interface near the ligament region, assuming a more random orientation through the bulk of the interface. Proteoglycan content was uniform on average across the insertion, while its distribution was relatively less variable at the tibial compared to the femoral insertion. Mineral was only detected in the calcified interface region, and its content increased exponentially across the mineralized fibrocartilage region toward bone. In addition to new insights into matrix composition and organization across the complex multi-tissue junction, findings from this study provide critical benchmarks for the regeneration of soft tissue-to-bone interfaces and integrative soft tissue repair.

Proline/arginine-rich end leucine-rich repeat protein converts stem cells to ligament tissue and Zn(II) influences its nuclear expression

Our objective was to facilitate ligament tissue reconstruction by characterizing the mechanism of expression of ligament tissue. To accomplish this, we searched for proteins specific to the tissue and introduced them into mesenchymal stem cells. In the two-dimensional phosphorescent gel electrophoresis, the spots in common with the normal human ligament tissue were selected after removing the spots of the normal bone tissue from those of the ossified tissue in the spinal ligament. Proline/arginine-rich end leucine-rich repeat protein (PRELP) was identified in ligament-specific locations by liquid chromatography-tandem mass spectrometry. Transfection of PRELP into mouse mesenchymal stem cells yielded ligament-like connective tissue comprised of parallel fibers. Thus, expression of the PRELP protein could reconstruct the ligament tissue. Since zinc-related proteins were found with high incidence as a result of an array analysis of PRELP's ProtoArray, it was considered that there is a relationship to the zinc metabolism. Tissue induction was mediated by the tumor necrosis factor (TNF)-α via the zinc pathway. PRELP may be a useful gene in syndesmoplasty, provided zinc is present for tissue reconstruction. Chromosome division becomes active with the addition of zinc, and rapid tissue induction takes place in the presence of zinc and TNF-α. Currently, the reconstruction of a ruptured ligament tissue is difficult, but we expect that the PRELP protein expression may facilitate this process. This study describes the discovery of the gene responsible for the differentiation of stem cells into ligament tissue. This important finding may lead to treatments for gonarthrosis, cruciate ligament, and periodontal ligament ruptures, and ossification of the posterior longitudinal ligament.

Effects of mechanical strain on human mesenchymal stem cells and ligament fibroblasts in a textured poly(L-lactide) scaffold for ligament tissue engineering

The purpose of this study was to prove the effect of cyclic uniaxial intermittent strain on the mRNA expression of ligament-specific marker genes in human mesenchymal stem cells (MSC) and anterior cruciate ligament-derived fibroblasts (ACL-fibroblasts) seeded onto a novel textured poly(L-lactide) scaffold (PLA scaffold). Cell-seeded scaffolds were mechanically stimulated by cyclic uniaxial stretching. The expression of ligament matrix gene markers: collagen types I and III, fibronectin, tenascin C and decorin, as well as the proteolytic enzymes matrix metalloproteinase MMP-1 and MMP-2 and their tissue specific inhibitors TIMP-1 and TIMP-2 was investigated by analysing the mRNA expression using reverse transcriptase polymerase chain reaction and related to the static control. In ACL-fibroblasts seeded on PLA, mechanical load induced up-regulation of collagen types I and III, fibronectin and tenascin C. No effect of mechanical stimulation on the expression of ligament marker genes was found in undifferentiated MSC seeded on PLA. The results indicated that the new textured PLA scaffold could transfer the mechanical load to the ACL-fibroblasts and improved their ligament phenotype. This scaffold might be suitable as a cell-carrying component of ACL prostheses.

[Expression of transient receptor potentials of vanilloid subtype 1 and pain in endometriosis]

OBJECTIVE

To investigate the expression of transient receptor potential vanilloid subtype 1 (TRPV1) in uterosacral ligament and its correlation with pain in endometriosis.

METHODS

Total of 54 patients undergoing endometriotic lesions excision in uteroscaral ligament by laparoscopy due to pelvic pain were enrolled in this study. According to visual analogue scale (VAS) scores, 27 patients with VAS 5-10 were in group A and 27 patients with VAS 0-4 were in group B. In the mean time, 20 patients with dysmenorrhea without endometriosis (VAS: 0-4) were matched as group C. Specimens (including the sacro-ligaments of 20 women without endometriosis) were immunostained with specific antibodies of TRPV1. Western blot and real time PCR were performed to detect TRPV1 expression in endometriosis lesions and control group.

RESULTS

(1) Immunohistochemnistry: the positive area of TRPV1 was found in endometriotic lesions in uterosacral ligament in group A, B and tissue of uterosacral ligament group C. The semi-qualitification of TRPV1 expression were 3 in group A, 1 in group B and 1 in group C by immunohistochemistry staining. There was significantly different expression between group B and group A (P = 0.005) or group C (P = 0.027). (2) mRNA expression:the expression of TRPV1 was 1.84 in group A, 0.80 in group B, 0.24 in group C, respectively. With higher VAS scores, the expression of TRPV1 exhibited increasing trends. The expression of TRPV1 mRNA was higher in group A than that in group B (P = 0.022). There was statistically different expression between group B and group C (P = 0.031). (3) Western blot: the expression of TRPV1 protein was 0.63 in group A, 0.19 in group B, 0.02 in group C. There was significant differences between group A and group B (P = 0.022), and between group B and group C (P < 0.01).

CONCLUSION

The expression of TRPV1 was correlated with the degree of pain in patient with endometriosis.

[Preliminary study on metabolism of collagen in uterus sacral ligament fibroblasts under stress]

OBJECTIVE

To detect the expression of type I collagen, type III collagen, prolyl-4-hydroxylases (PH4) and matrix metalloproteinase 1 (MMP-1) in sacral ligament fibroblasts under stress, to understand the collagen synthesis and metabolism in stress situations change.

METHODS

Eight patients who underwent abdominal hysterectomy for uterine benign disease were enrolled in this study. Primary sacral ligament fibroblasts were isolated by explant. After mechanical loading, gene expression of type I, III collagen, PH4 and MMP-1 were measured.

RESULTS

Stress of 8% continuing for 24 hours, collagen I (1.13 ± 0.24), collagen III (1.05 ± 0.31) mRNA expression and PH4 expression (1.11 ± 0.31) compared with static groups (1) showed increasing trends;when the stress were 4% and 12%, collagen I (0.86 ± 0.26 and 0.85 ± 0.25), collagen III showed increasing trends (0.74 ± 0.29 and 0.83 ± 0.38) mRNA expression were decreased. After removal of the stress, in the stress of 4% for 1 hour, collagen I (0.79 ± 0.40, 0.97 ± 0.24 and 1.46 ± 0.75), collagen III (0.86 ± 0.40, 0.99 ± 0.60 and 1.59 ± 0.82) and PH4 (1.11 ± 0.51, 1.17 ± 0.54 and 1.37 ± 0.39) mRNA expression increased gradually. In 8% stress group, collagen I mRNA expression (1.16 ± 0.62, 1.01 ± 0.51 and 1.05 ± 0.80) reached the peak in day 1, and collagen III (0.99 ± 0.69, 1.59 ± 0.55 and 1.03 ± 0.91) and PH4 (1.05 ± 0.31, 1.07 ± 0.80 and 0.85 ± 0.31) mRNA expression reached the peak in day 2, then decreased. 4% and 8% of the stress with time after the change, MMP-1 mRNA expression have peaked at day 1.

CONCLUSIONS

Moderate stress could contribute to pelvic floor collagen synthesis, too much or too little stress is not conducive to the synthesis of collagen. Collagen I and collagen III on the stress response may be different, the former have faster reaction than the latter. PH4 were involved in the synthesis of collagen, while MMP-1 may play a role in collagen degradation.

Effect of extracorporeal shock wave therapy on the biochemical composition and metabolic activity of tenocytes in normal tendinous structures in ponies

REASONS FOR PERFORMING STUDY

Extracorporeal shockwave therapy (ESWT) has recently been introduced as a new therapy for tendon injuries in horses, but little is known about the basic mechanism of action of this therapy.

OBJECTIVES

To study the effect of ESWT on biochemical parameters and tenocyte metabolism of normal tendinous structures in ponies.

METHODS

Six Shetland ponies, free of lameness and with ultrasonographically normal flexor and extensor tendons and suspensory ligaments (SL), were used. ESWT was applied at the origin of the suspensory ligament and the mid-metacarpal region of the superficial digital flexor tendon (SDFT) 6 weeks prior to sample taking, and at the mid-metacarpal region (ET) and the insertion on the extensor process of the distal phalanx (EP) of the common digital extensor tendon 3 h prior to tendon sampling. In all animals one front leg was treated and the other front leg was used as control. After euthanasia, tendon explants were harvested aseptically for in vitro cell culture experiments and additional samples were taken for biochemical analyses.

RESULTS

In the explants harvested 3 h after treatment, glycosaminoglycan (GAG) and protein syntheses were increased (P<0.05). The synthesis of all measured parameters was decreased 6 weeks after ESWT treatment. Biochemically, the level of degraded collagen was increased 3 h after treatment (P<0.05). Six weeks after treatment, there was a decrease of degraded collagen and GAG contents. DNA content had not changed in either tendon samples or explants after culturing.

CONCLUSIONS

ESWT causes a transient stimulation of metabolism in tendinous structures of ponies shortly after treatment. After 6 weeks metabolism has decreased significantly and GAG levels are lower than in untreated control limbs.

POTENTIAL RELEVANCE

The stimulating short-term effect of ESWT might accelerate the initiation of the healing process in injured tendons. The long-term effect seems less beneficial. Further research should aim at determining the duration of this effect and at assessing its relevance for end-stage tendon quality.

[Expression of androgen receptor in the vaginal wall and cardinal ligament of patients with pelvic organ prolapse]

OBJECTIVE

To evaluate the role of androgen and its receptor in the pathogenesis of prolapse of pelvic floor.

METHODS

Specimens of right cardinal ligament and vaginal wall were collected from 38 patients with prolapse, aged (64 +/- 3) (45 - 79), all menopausal, and 23 women, aged (50 +/- 2)(45-57), with obstetric or gynecologic diseases other than prolapse (as controls), all undergoing total hysterectomy. The 38 prolapse patients were divided into 2 groups: Group > or = 60, aged (66 +/- 6), and Group < 60, aged (52 +/- 5). Western blotting and immunohistochemistry were used to detect the expression of androgen receptor (AR) in the tissues. Peripheral blood samples were collected from all patients to examine the levels of serum testosterone and sex hormone binding globulin (SHBG) by chemiluminescent labeling.

RESULTS

There were no significant differences in the serum concentrations of testosterone and SHBG between the prolapse and the control groups. The AR positive rates in the cardinal ligament and vaginal wall tissues of the prolapse patients aged > or = 60 were (49 +/- 15)% and (49 +/- 10)% respectively, both not significantly different from those of the control group [(43 +/- 15)% and (42 +/- 3)% respectively, both P > 0.05]. ears, The AR expression rates in the tissues of cardinal ligament and vaginal wall of the prolapse patients were (42 +/- 3)% and (43 +/- 15)% respectively, both significantly higher than those of the control group [(29 +/- 7)% and (29 +/- 6)% respectively, both P < 0.001]. Western blotting showed that the positive rate of the AR with the relative molecular weight of 45 000 in the cardinal ligament of the prolapse group was 4.41%, significantly higher than that of the control group (2.1%, P = 0.02), however, the positive rate of the AR with the relative molecular weight of 45 000 in the vaginal wall tissue of the prolapse group was 3.34%, not significantly different from that of the control group (2.28%, P = 0.2). There were no significant differences in the in the straps of 110 000 and 90 000 detected by C-terminal polyantibodies of AR in the cardinal ligament and vaginal wall tissues between the prolapse patients and the control group (both P > 0.05).

CONCLUSION

The increasing expression of AR in the tissue of vaginal wall and cardinal ligament of the prolapse patients with pelvic floor dysfunction may play an important role in the etiology of pelvic floor dysfunction.

[Expression of elastin, lysyl oxidase and elafin in the cardinal ligament of women with pelvic organ prolapse]

OBJECTIVE

To investigate expression of elastin, lysyl oxidase (LOX) and elafin in cardinal ligament of women with pelvic organ prolapse (POP) so as to determine their contributions to POP.

METHODS

The cardinal ligament samples were obtained from 60 POP subjects and 60 non-POP control women undergoing hysterectomy. RT-PCR was used to verify the mRNA level of elastin, LOX and elafin. The protein concentration of the three genes was determined by western blotting technique, electrophoretic separation and quantification.

RESULTS

The premenopausal and postmenopausal POP groups demonstrated significantly decreased expressions of elastin in cardinal ligament both in mRNA and protein levels than control group (mRNA 0.42 +/- 0.22, 0.26 +/- 0.20 versus 0.79 +/- 0.30, 0.63 +/- 0.23; protein 0.44 +/- 0.32, 0.20 +/- 0.19 versus 0.89 +/- 0.27, 0.78 +/- 0.25; P < 0.05). There was an identical tendency in the expression of LOX (mRNA 0.37 +/- 0.18, 0.20 +/- 0.14 versus 0.65 +/- 0.22, 0.53 +/- 0.20; protein 0.45 +/- 0.27, 0.26 +/- 0.21 versus 0.85 +/- 0.39, 0.69 +/- 0.31; P < 0.05). In POP group, the mRNA and protein levels of elastin and LOX in postmenopausal patients were significantly lower than premenopausal patients (P < 0.05). Inversely, POP group demonstrated an increased expression of elafin in cardinal ligament both in mRNA and protein levels than corresponding control group (mRNA 1.33 +/- 0.35, 1.47 +/- 0.37 versus 0.62 +/- 0.25, 0.55 +/- 0.24; protein 0.85 +/- 0.30, 0.76 +/- 0.35 versus 0.21 +/- 0.15, 0.29 +/- 0.22; P < 0.05). There was no significant difference in the expression of elafin between premenopausal and postmenopausal POP groups either in mRNA or protein levels (P > 0.05). There was a positive correlation between elastin and LOX both in mRNA and protein levels in POP group(r = 0.9959, 0.9708; P < 0.05), but there was no correlation between elastin and elafin (r = -0.0402, -0.0365; P > 0.05).

CONCLUSIONS

The results suggest that the decreased expression of elastin and LOX and the increased expression of elafin in the cardinal ligaments may contribute to POP.

[Changes of collagen content in uterine ligaments of perimenopausal women with relaxation of pelvic supports]

OBJECTIVE

To investigate the changes in histological characteristics and collagen content in uterosacral and cardinal ligaments of perimenopausal women in relation to relaxation of pelvic supports.

METHODS

Twenty-eight subjects undergoing hysterectomies were selected, in which 14 cases were perimenopausal women with relaxation of pelvic support as the relaxation group and 14 women at perimenopausal age with leomyoma, cervical cancer, adenomyosis as the control group. Samples of cardinal ligaments and uterosacral ligaments were obtained at hysterectomies, and the tissues were sliced and stained by Masson's trichrome technique. Histological characteristics of the samples were studied and immunohistochemistry assay was applied to demonstrate the contents of collagen types I and III.

RESULTS

(1) The collagen in uterosacral ligaments and cardinal ligaments were stained blue by the Masson's trichome technique. In comparison to the control group, the relaxation group had milder positive stains of the collagen and the stains were distributed in unequal intensities. Collagen content was arranged in loose pattern. Focal arrangement of the collagen was dense but fragmented. Collagen fibers were atrophic. (2) In immunohistochemistry assay and image analysis, collagen was positive in light to deep brown areas. In the relaxation group, positive units of collagen types I and III in cardinal ligaments were 13.8 +/- 2.1 and 9.6 +/- 2.4 respectively. Positive units of collagen types I and III of cardinal ligaments in the control group were 27.4 +/- 3.5 and 17.7 +/- 4.0 respectively. Differences between these two groups were statistically significant (P<0.01). In the relaxation group, positive units of collagen types I and III in utero-sacral ligaments were 15. 8 +/- 2.5 and 10.3 +/- 3.6 respectively. Positive units of collagen types I and III of utero-sacral ligaments of the control group were 29.5 +/- 4.4 and 19.3 +/- 4.6 respectively. Differences between these two groups were statistically significant (P<0.01).

CONCLUSIONS

Reductions in collagen types I and III occur in pelvic floor tissue of perimenopausal patients who suffer from pelvic support relaxation. Atrophic and degenerative changes of collagen fibers may be the basic pathological structural alteration in pelvic floor.

[Expression of neuropeptide Y and its receptors in the cardinal ligaments and uterosacral ligaments in patients with pelvic organ prolapse]

OBJECTIVE

To evaluate the distribution of neuropeptide Y and its receptors in the cardinal ligament and uterosacral ligaments in women with and without pelvic organ prolapse (POP).

METHODS

Sixteen patients with pelvic organ prolapse entered the study. All patients were evaluated by pelvic organ prolapse quantitation (POP-Q). Group A consisted of six patients with grade I , II POP, and group B comprised ten patients with grade III, IV POP. Eight nonfunctional ovarian tumor patients without POP were recruited as control subjects. Biopsies of cardinal ligament and uterosacral ligament were obtained from each woman during surgery. Immunohistochemical study with polyclonal antibody against a general nerve marker S-100 and neuropeptide Y was performed on paraffin-embedded sections of all the samples. In addition, mRNA levels of the human NPY-Y1 and NPY-Y2 receptors were assessed in both patients and controls.

RESULTS

(1) NPY immunoreactivities were identified in both cardinal ligament and uterosacral ligament NPY immunoreactive nerve fibers were insignificantly lower in POP patients (P > 0.05). The distribution pattern of NPY was similar in cardinal ligament and uterosacral ligament (P > 0.05). (2) mRNAs encoding the NPY-Y1 and NPY-Y2 receptors were detected in the pelvic supporting tissues. Besides the expected NPY-Y1 PCR products, an additional 97 bp long amplicon originating from an alternative splicing event was found in most tissues studied. (3) In cardinal ligaments, mRNA encoding NPY-Y1 receptor had a significant difference between group A (3.9 +/- 1.0) and B (6.0 +/- 1.5), and between control (3.4 +/- 0.9) and group B (P = 0.019, P = 0.004), while there was no significant difference between group A and controls (P = 0.082). In uterosacral ligaments, mRNA encoding NPY-Y1 receptor had no significant difference between Group A (6.0 +/- 1.1) and B (6.3 +/- 0.7), or between group A and controls (4.8 +/- 0.7; P = 0.151, P = 0.690); while there was a significant difference between group B and controls (P = 0.016). (4) mRNA encoding NPY-Y2 receptor had no significant difference between controls (0.49 +/- 0.34, 0.61 +/- 0.15), group A (0.56 +/- 0.21, 0.67 +/- 0.13) and group B (0.85 +/- 0.43, 0.69 +/- 0.21) patients in cardinal ligament and uterosacral ligaments (P > 0.05). (5) mRNA encoding NPY-Y1 (P = 0.084) and NPY-Y2 (P = 0.470) receptors had no significant difference between cardinal ligament and uterosacral ligament.

CONCLUSIONS

There are NPY and NPY receptors in cardinal and uterosacral ligaments. The increased expression of NPY Y1 receptor may be related to local blood flow reduction and structural changes of pelvic supporting tissue.

Temporal extracellular matrix adaptations in ligament during wound healing and hindlimb unloading

Previous data from spaceflight studies indicate that injured muscle and bone heal slowly and abnormally compared with ground controls, strongly suggesting that ligaments or tendons may not repair optimally as well. Thus the objective of this study was to investigate the biochemical and molecular gene expression of the collagen extracellular matrix in response to medial collateral ligament (MCL) injury repair in hindlimb unloaded (HLU) rodents. Male rats were assigned to 3- and 7-wk treatment groups with three subgroups each: sham control, ambulatory healing (Amb-healing), and HLU-healing groups. Amb- and HLU-healing animals underwent bilateral surgical transection of their MCLs, whereas control animals were subjected to sham surgeries. All surgeries were performed under isoflurane anesthesia. After 3 wk or 7 wk of HLU, rats were euthanized and MCLs were surgically isolated and prepared for molecular or biochemical analyses. Hydroxyproline concentration and hydroxylysylpyridinoline collagen cross-link contents were measured by HPLC and showed a substantial decrement in surgical groups. MCL tissue cellularity, quantified by DNA content, remained significantly elevated in all HLU-healing groups vs. Amb-healing groups. MCL gene expression of collagen type I, collagen type III, collagen type V, fibronectin, decorin, biglycan, lysyl oxidase, matrix metalloproteinase-2, and tissue inhibitor of matrix metalloproteinase-1, measured by real-time quantitative PCR, demonstrated differential expression in the HLU-healing groups compared with Amb-healing groups at both the 3- and 7-wk time points. Together, these data suggest that HLU affects dense fibrous connective tissue wound healing and confirms previous morphological and biomechanical data that HLU inhibits the ligament repair processes.

Immunohistochemical demonstration of advanced glycation end products and the effects of advanced glycation end products in ossified ligament tissues in vitro

STUDY DESIGN

This study correlates advanced glycation end products with ossified ligament tissues of the cervical spine in vitro.

OBJECTIVE

To investigate the effect of advanced glycation end products on ossification of the spinal ligaments in vitro.

SUMMARY OF BACKGROUND DATA

We have hypothesized that an accumulation of advanced glycation end products in the spinal ligament might result in some observable change in specific growth factors responsible for ossification in the spinal ligaments.

METHODS

Samples of the posterior longitudinal and yellow ligaments were harvested from patients (n = 5) with ossification of the posterior longitudinal ligament, and analyzed for the presence of advanced glycation end products and their receptor advanced glycation end product receptor by immunohistochemistry. Real-time polymerase chain reaction (PCR) was used to quantify the messenger ribonucleic acid (mRNA) levels of bone morphogenetic protein (BMP)-2, BMP-7, alkaline phosphatase, an osteoblast-specific transcription factor 1 (Cbfa1), and osteocalcin from yellow ligament cells treated with advanced glycation end products.

RESULTS

Immunohistochemical analysis revealed that advanced glycation end products and advanced glycation end product receptor were localized to within the posterior longitudinal and yellow ligaments. Advanced glycation end products were found to increase significantly the expression of BMP-2, BMP-7, Cbfa1, and osteocalcin at the mRNA levels after treatment with advanced glycation end products (1 microg/mL).

CONCLUSIONS

This is the first report to investigate the correlation, if any, between the ossified spinal ligament and advanced glycation end products. These results suggested that accumulation in advanced glycation end products and their interaction with advanced glycation end product receptor were 1 of the important risk factors in the process of ossification in the spinal ligaments.

Tendons and ligaments are anatomically distinct but overlap in molecular and morphological features--a comparative study in an ovine model

Tendons and ligaments are similar in composition but differ in function. Simple anatomical definitions do not reflect the fact individual tendons and ligaments have unique properties due to their adaptation to a specific role. The patellar tendon is a structure of particular clinical interest. A null hypothesis was declared stating that the patellar tendon is not significantly different in terms of matrix composition and collagen fibril diameter to other tendons. The lateral and medial collateral ligaments (LCL, MCL), anterior and posterior cruciate ligaments (ACL, PCL), together with the long digital extensor, superficial digital extensor, and patellar tendons (LDET, SDFT, PT) were harvested from three cadaveric ovine hindlimbs. The extracellular matrix was assessed in terms of water, collagen, and total sulphated glycosaminoglycan (GAG) content. The organization of the collagen component was determined by an ultrastructural analysis of collagen fibril diameter distributions, together with values for the collagen fibril index (CFI) and mass-average diameter (MAD). There were significant differences between ligaments and tendons. The PT had a bimodal collagen fibril diameter distribution with CFI 72.9%, MAD 202 nm, water content 53.1%, GAG content 2.3 microg/mg, and collagen content 73.7%, which was not significantly different from the other tendons. The results of this study support the null hypothesis suggesting that the patellar tendon is similar to other tendons and demonstrate that tendons have different characteristics to ligaments.

Tumour necrosis factor alpha-stimulated gene-6 inhibits osteoblastic differentiation of human mesenchymal stem cells induced by osteogenic differentiation medium and BMP-2

To better understand the molecular pathogenesis of OPLL (ossification of the posterior longitudinal ligament) of the spine, an ectopic bone formation disease, we performed cDNA microarray analysis on cultured ligament cells from OPLL patients. We found that TSG-6 (tumour necrosis factor alpha-stimulated gene-6) is down-regulated during osteoblastic differentiation. Adenovirus vector-mediated overexpression of TSG-6 inhibited osteoblastic differentiation of human mesenchymal stem cells induced by BMP (bone morphogenetic protein)-2 or OS (osteogenic differentiation medium). TSG-6 suppressed phosphorylation and nuclear accumulation of Smad 1/5 induced by BMP-2, probably by inhibiting binding of the ligand to the receptor, since interaction between TSG-6 and BMP-2 was observed in vitro. TSG-6 has two functional domains, a Link domain (a hyaluronan binding domain) and a CUB domain implicated in protein interaction. The inhibitory effect on osteoblastic differentiation was completely lost with exogenously added Link domain-truncated TSG-6, while partial inhibition was retained by the CUB domain-truncated protein. In addition, the inhibitory action of TSG-6 and the in vitro interaction of TSG-6 with BMP-2 were abolished by the addition of hyaluronan. Thus, TSG-6, identified as a down-regulated gene during osteoblastic differentiation, suppresses osteoblastic differentiation induced by both BMP-2 and OS and is a plausible target for therapeutic intervention in OPLL.

Age-dependent changes in matrix composition and organization at the ligament-to-bone insertion

Injuries to the anterior cruciate ligament (ACL) often occur at the ligament-to-bone insertion site; thus, an in-depth understanding of the native insertion is critical in identifying the etiology of failure and devising optimal treatment protocols for ACL injuries. The objective of this study is to conduct a systematic characterization of the ACL-to-bone interface, focusing on structural and compositional changes as a function of age. Using a bovine model, three age groups were studied: Neonatal (1-7 days old), Immature (2-6 months old), and Mature (2-5 years old). The distribution of types I, II, X collagen, decorin, cartilage oligomeric matrix protein (COMP), glycosaminoglycan (GAG), alkaline phosphatase (ALP) activity, and minerals at the ACL-to-bone insertion were examined. Additionally, cell aspect ratio, size, and distribution across the insertion were quantified. The ACL-to-bone insertion is divided into four regions: ligament, nonmineralized interface, mineralized interface, and bone. Both region-dependent and age-dependent structural and compositional changes at the insertion site were observed in this study. The interface in the skeletally immature group resembled articular cartilage, while the adult interface was similar to fibrocartilaginous tissue. Age-dependent changes in extracellular matrix composition (type X collagen, sulfated glycosaminoglycan), cellularity, ALP activity, and mineral distribution were also found. Marked differences in collagen fiber orientation between the femoral and tibial insertions were observed, and these differences became more pronounced with age.

Stimulatory effects of distinct members of the bone morphogenetic protein family on ligament fibroblasts

OBJECTIVE

To investigate effects of cartilage derived morphogenetic protein-1 and -2 (CDMP-1, CDMP-2), bone morphogenetic protein (BMP)-7 and BMP-6 on metabolism of ligament fibroblasts and their osteogenic or chondrogenic differentiation potential.

METHODS

Ligament fibroblasts were obtained from 3 month old calves, plated as monolayers or micromass cultures, and incubated with or without CDMP-1, CDMP-2, BMP-7, and BMP-6. Expression of the indicated growth factors was assessed by RT-PCR and western immunoblotting. The presence of their respective type I and II receptors, and lineage related markers, was investigated in stimulated and unstimulated cells by RT-PCR and northern blotting. Biosynthesis of matrix proteoglycans was assessed by [(35)S]sulphate incorporation in monolayers. Alcian blue and toluidine blue staining was done in micromass cultures.

RESULTS

CDMP-1, CDMP-2, BMP-7, and BMP-6 were detected on mRNA and on the protein level. Type I and II receptors were endogenously expressed in unstimulated ligament fibroblasts. The growth factors significantly stimulated total proteoglycan synthesis as assessed by [(35)S]sulphate incorporation. Toluidine blue staining showed cartilage-specific metachromasia in the growth factor treated micromass cultures. Transcription analysis of stimulated ligament fibroblasts demonstrated coexpression of chondrocyte markers but no up regulation of osteogenic markers.

CONCLUSION

CDMP-1, CDMP-2, BMP-7, and BMP-6 and their receptors were expressed in ligament tissue. These growth factors induced matrix synthesis in fibroblasts derived from bovine ligament. The preferential expression of cartilage markers in vitro suggests that CDMP-1, CDMP-2, BMP-7, and BMP-6 have the potential to induce differentiation towards a chondrogenic phenotype in ligament fibroblasts. Thus, fibroblasts from ligaments may serve as a source for chondrogenesis and tissue repair.

Coordinate expression of BMP-2, BMP receptors and Noggin in normal mouse spine

The purpose of this study was to determine the localization of bone morphogenetic protein-2 (BMP-2), BMP receptors (BMPRs) and Noggin in mouse spinal tissues. The coordinate expression of these positive and negative regulators of BMP signaling may elucidate regulatory mechanisms for bone induction in the spine. Whole spines from 3-week-old mice were used and the spatial expression profiles of BMP-2, BMPR-1a, -1b, -2 and Noggin were examined using in situ hybridization. BMP-2, BMPR-1b and -2 were observed in bone marrow cells in the vertebrae, chondrocytes, hyaline cartilage cells and fibrous cells in the intervertebral discs and neurons of the spinal cord in the entire spine. BMPR-1a was also observed in these cells, but only in the cervical spine. Noggin was expressed in bone marrow cells in the vertebrae, chondrocytes and hyaline cartilage cells and fibrous cells in the intervertebral discs in the entire spine and in neurons in the spinal cord in the cervical and thoracic regions. Noggin was also expressed in the anterior longitudinal, posterior longitudinal and yellow ligaments in the cervical spine, and in the fibrous cells in the anterior longitudinal and yellow ligaments of the lumbar spine.

VEGF, VEGFR-1 and VEGFR-2 immunoreactivity in the porcine arteries of vascular subovarian plexus (VSP) during the estrous cycle

Abstract: Vascular endothelial growth factor (VEGF) is an important angiogenic factor in the female reproductive tract. It binds to cell surface through ligand-stimulatable tyrosine kinase receptors, the most important being VEGFR-1 (flt-1) and VEGFR-2 (flk-1). The broad ligament of the uterus is a dynamic organ consisting of specialized complexes of blood vessels connected functionally to the uterus, oviduct and ovary. Endothelial cells form an inner coating of the vessel walls and thus they stay under the influence of various modulators circulating in blood including ovarian steriods involved in developmental changes in the female reproductive system. The aim of the present study was to immunolocalize VEGF and its two receptors: VEGFR-1 and VEGFR-2 in the broad ligament of the uterus in the area of vascular subovarian plexus during different phases of the estrous cycle in pig and to determine the correlation between immunoreactivity of the investigated factors and phases of the estrous cycle. The study was performed on cryostat sections of vascular subovarian plexus stained immunohistochemically by ABC method. Specific polyclonal antibodies: anti-VEGF, anti-VEGFR-1 and anti-VEGFR-2 were used. Data were subjected to one-way analysis of variance. Our study revealed the presence of VEGF and its receptors in endothelial and smooth muscle cells of VSP arteries. All agents displayed phase-related differences in immunoreactivity suggesting the modulatory effect of VEGF, VEGFR-1 and VEGFR-2 on the arteries of the VSP in the porcine broad ligament of the uterus.

Anabolic effects of acellular bone marrow, platelet rich plasma, and serum on equine suspensory ligament fibroblasts in vitro

The purpose of this study was to investigate the response of suspensory ligament fibroblasts (SLF) to in vitro stimulation using acellular bone marrow (ABM), platelet rich plasma (in vitro PRP), and serum as potential treatment modalities for suspensory desmitis. Blood, bone marrow, and suspensory ligaments were collected from five horses. SLF were harvested, grown until confluent, and stimulated with various concentrations of ABM, PRP, equine serum, foetal bovine serum, and medium (control). The responses to the treatments were assessed using a combination of radio-labeling for total protein synthesis and an ELISA for quantification of Cartilage Oligomeric Matrix Protein (COMP) production. Addition of all of the samples resulted in significant increases in COMP and total protein synthesis over controls (P<0.001). ABM caused the greatest increase in both COMP and total protein synthesis by the SLF. Equine ABM, PRP, and serum contain anabolic factors that promote matrix synthesis by SLF in vitro, with ABM having the greatest effect. Application of bone marrow to injured ligaments may enhance healing by providing anabolic factors, other than or in addition to mesenchymal stem cells, which stimulate matrix production.

Soluble phosphate glass fibres for repair of bone-ligament interface

Phosphate-based fibres of the generic composition (CaO)0.46-(Na2O)n-(Fe2O3)y-(P2O5)0.50 have been evaluated, in vitro, as three dimensional scaffolds for tissue engineering of the hard-soft tissue interface by assessing the fibre solubility and growth and functional gene expression of human cells. Primary human osteoblasts and fibroblasts were seeded onto scaffolds and maintained in culture for up to 21 days. Fluorescent immunolabeling revealed the spread cell morphology and significant proliferation pattern on these fibres, particularly on the 3 mol% Fe2O3-containing formulation. Real-time quantitative Polymerase Chain Reaction (rtQ-PCR) analysis of gene expression using TaqMan Probes was preformed and it has been established that committed cell differentiation was maintained by both cell types, and was strongly related to the 3 mol% Fe2O3 glass composition. These novel, readily manufactured, soluble glass fibres offer a biocompatible and biochemically favourable alternative in the search for suitable degradable materials used in Tissue Engineering.

Collagen synthesis in human musculoskeletal tissues and skin

We have developed a direct method for the measurement of human musculoskeletal collagen synthesis on the basis of the incorporation of stable isotope-labeled proline or leucine into protein and have used it to measure the rate of synthesis of collagen in tendon, ligament, muscle, and skin. In postabsorptive, healthy young men (28 +/- 6 yr) synthetic rates for tendon, ligament, muscle, and skin collagen were 0.046 +/- 0.005, 0.040 +/- 0.006, 0.016 +/- 0.002, and 0.037 +/- 0.003%/h, respectively (means +/- SD). In postabsorptive, healthy elderly men (70 +/- 6 yr) the rate of skeletal muscle collagen synthesis is greater than in the young (0.023 +/- 0.002%/h, P < 0.05 vs. young). The rates of synthesis of tendon and ligament collagen are similar to those of mixed skeletal muscle protein in the postabsorptive state, whereas the rate for muscle collagen synthesis is much lower in both young and elderly men. After nutrient provision, collagen synthesis was unaltered in tendon and skeletal muscle, remaining at postabsorptive values (young: tendon, 0.045 +/- 0.008%/h; muscle, 0.016 +/- 0.003%/h; elderly: muscle, 0.024 +/- 0.003%/h). These results demonstrate that the rate of human musculoskeletal tissue collagen synthesis can be directly and robustly measured using stable isotope methodology.