Effect of Vaginal Microecological Alterations on Female Pelvic Organ Prolapse

INTRODUCTION AND HYPOTHESIS

The objective was to investigate the correlation between endogenous vaginal microecological alterations and female pelvic organ prolapse (POP).

METHODS

Patients who underwent vaginal hysterectomy were retrospectively analyzed as the POP group (n = 30) and the non-POP group (n = 30). The vaginal microbial metabolites and enzyme levels were tested using the dry chemoenzymatic method. The mRNA and protein expression were tested using real-time quantitative PCR and immunohistochemistry. SPSS version 25.0 and GraphPad Prism 8.0 were performed for statistical analysis.

RESULTS

Compared with the non-POP group, the vaginal pH, H2O2 positivity and leukocyte esterase positivity were higher in patients with POP (all p < 0.05). Further analysis showed that patients with pelvic organ prolapse quantification (POP-Q) stage IV had higher rates of vaginal pH, H2O2 positivity and leukocyte esterase positivity than those with POP-Q stage III. Additionally, the mRNA expression of decorin (DCN), transforming growth factor beta 1 (TGF-β1), and matrix metalloproteinase-3 (MMP-3) in uterosacral ligament tissues were higher, whereas collagen I and III were lower. Similarly, the positive expression of MMP-3 in uterosacral ligament tissue was significantly upregulated in the POP group compared with the non-POP group (p = 0.035), whereas collagen I (p = 0.004) and collagen III (p = 0.019) in uterosacral ligament tissue were significantly downregulated in the POP group. Correlation analysis revealed that there was a significant correlation between vaginal microecology and collagen metabolism. In addition, MMP-3 correlated negatively with collagen I and collagen III (p = 0.002, r = -0.533; p = 0.002, r = -0.534 respectively), whereas collagen I correlated positively with collagen III (p = 0.001, r = 0.578).

CONCLUSIONS

Vaginal microecological dysbiosis affects the occurrence of female POP, which could be considered a novel therapeutic option.

Single-cell analysis of uterosacral ligament revealed cellular heterogeneity in women with pelvic organ prolapse

Pelvic organ prolapse (POP) markedly affects the quality of life of women, including significant financial burden. Using single-cell RNA sequencing, we constructed a transcriptional profile of 30,452 single cells of the uterosacral ligament in POP and control samples, which has never been constructed before. We identified 10 major cell types, including smooth muscle cells, endothelial cells, fibroblasts, neutrophils, macrophages, monocytes, mast cells, T cells, B cells, and dendritic cells. We performed subpopulation analysis and pseudo-time analysis of POP primary cells, and explored differentially expressed genes. We verified previous cell clusters of human neutrophils of uterosacral ligaments. We found a significant reduction in receptor-ligand pairs related to ECM and cell adhesion between fibroblasts and endothelial cells in POP. The transcription factors related to the extracellular matrix, development, and immunity were identified in USL. Here we provide insight into the molecular mechanisms of POP and valuable information for future research directions.

Quercetin antagonized advanced glycated end products induced apoptosis and functional inhibition of fibroblasts from the prolapsed uterosacral ligament

The altered behaviors and functions of pelvic floor fibroblasts are pathophysiological changes of pelvic organ prolapse (POP). Our previous study showed that advanced glycated end products (AGEs) accumulated in the pelvic tissues of POP and induced fibroblast apoptosis. The study was designed to investigate whether quercetin antagonize AGEs-induced apoptosis and functional inhibition of fibroblasts. The uptake of 5-ethynyl-2'-deoxyuridine (EdU) was evaluated for cell proliferation. Flow cytometric analysis was applied for cell apoptosis. Intracellular reactive oxygen species (ROS) content was determined by the fluorescence of dichlorofluorescein (DCF). The contractility of fibroblasts was measured by collagen gel contraction assay. The expressions of extracellular matrix (ECM) related genes and the expression of miR-4429 and caspase-3 were quantified by qPCR. The expressions of phosphatase and tensin homolog (PTEN), phosphoinositide 3-kinase (PI3K), serine-threonine kinase (Akt), and phosphorylated Akt (p-Akt) were analyzed by Western Blot. The down-regulation of miR-4429 was achieved by cell transfection. Quercetin antagonized AGEs-induced apoptosis, proliferation inhibition, and ROS increase in fibroblasts. Quercetin did not alleviate AGEs-induced contractile impairment of fibroblasts. Quercetin reduced the gene expressions of lysyl oxidase like protein 1 (LOXL1)and matrix metallopeptidase 1 (MMP1), and increased the gene expressions of lysyl oxidase (LOX) and fibrillin 2 (FBN2) in fibroblasts. Quercetin reversed AGEs-induced upregulation of PTEN and downregulation of PI3K, P-Akt, and miR-4429 in fibroblasts. The inhibitory effect of quercetin on AGEs-induced fibroblast apoptosis was inhibited by downregulating the expression of miR-4429. In conclusion, quercetin antagonized AGEs-induced apoptosis and functional inhibition of fibroblasts from the prolapsed uterosacral ligament. And inhibiting AGEs-induced down-regulation of miR-4429/PTEN/PI3K/Akt pathway was the mechanism underlying the antagonistic effect of quercetin on AGEs-induced apoptosis.

Estrogen and Androgen Receptor Status in Uterosacral Ligaments of Women with Pelvic Organ Prolapse Stratified by the Pelvic Organ Prolapse Histology Quantification System

Menopause is a significant risk factor for pelvic organ prolapse (POP), suggesting that ovarian sex steroids play a major role in the etiology of the condition. POP results from failure of the uterine-cervix-vagina support structures, including the uterosacral ligament (USL). We previously identified consistent degenerative USL phenotypes that occur in POP and used their characteristics to develop a standardized POP Histologic Quantification System (POP-HQ). In this study, POP and matched control USL tissue was first segregated into the unique POP-HQ phenotypes, and specimens were then compared for estrogen receptor (ER) alpha (ERα), ERbeta (ERβ), the G-protein estrogen receptor (GPER), and androgen receptor (AR) content via immunohistochemical staining. ER and AR expression levels in the control USL tissues were indistinguishable from those observed in the POP-A phenotype, and partially overlapped with those of the POP-I phenotype. However, control-USL steroid receptor expression was statistically distinct from the POP-V phenotype. This difference was driven mainly by the increased expression of GPER and AR in smooth muscle, connective tissue, and endothelial cells, and increased expression of ERα in connective tissue. These findings support a multifactorial etiology for POP involving steroid signaling that contributes to altered smooth muscle, vasculature, and connective tissue content in the USL. Furthermore, these data support the concept that there are consistent and distinct degenerative processes that lead to POP and suggest that personalized approaches are needed that target specific cell and tissues in the pelvic floor to treat or prevent this complex condition.

Age-related changes in microRNAs expression in cruciate ligaments of wild-stock house mice

Cruciate ligaments (CL) of the knee joint are injured following trauma or aging. MicroRNAs (miRs) are potential therapeutic targets in musculoskeletal disorders, but there is little known about the role of miRs and their expression ligaments during aging. This study aimed to (1) identify if mice with normal physical activity, wild-stock house mice are an appropriate model to study age-related changes in the knee joint and (2) investigate the expression of miRs in aging murine cruciate ligaments. Knee joints were collected from 6 and 24 months old C57BL/6 and wild-stock house mice (Mus musculus domesticus) for ligament and cartilage (OARSI) histological analysis. Expression of miR targets in CLs was determined in 6-, 12-, 24-, and 30-month-old wild-stock house mice, followed by the analysis of predicted mRNA target genes and Ingenuity Pathway Analysis. Higher CL and knee OARSI histological scores were found in 24-month-old wild-stock house mice compared with 6- and 24-month-old C57BL/6 and 6-month-old wild-stock house mice (p < 0.05). miR-29a and miR-34a were upregulated in 30-month-old wild-stock house mice in comparison with 6-, 12-, and 24-month-old wild-stock house mice (p < 0.05). Ingenuity Pathway Analysis on miR-29a and 34a targets was associated with inflammation through interleukins, TGFβ and Notch genes, and p53 signaling. Collagen type I alpha 1 chain (COL1A1) correlated negatively with both miR-29a (r = -0.35) and miR-34a (r = -0.33). The findings of this study support wild-stock house mice as an appropriate aging model for the murine knee joint. This study also indicated that miR-29a and miR-34a may be potential regulators of COL1A1 gene expression in murine CLs.

Treatment of Pelvic Organ Prolapse by the Downregulation of the Expression of Mitofusin 2 in Uterosacral Ligament Tissue via Mesenchymal Stem Cells

Background: The relationship between pelvic organ prolapse (POP), an aging-related disease, and the senescence-related protein mitofusin 2 (Mfn2) has rarely been studied. The aim of the present study was to explore the therapeutic effects of the downregulation of Mfn2 expression by stem cells on POP through animal experiments. Methods: First, a rat POP model was constructed by ovariectomy and traction. The rats in the non-pelvic organ prolapse (NPOP) and POP groups were divided into four groups for negative controls (N1−N4, N1: NPOP-normal saline; N2: NPOP-untransfected stem cells; N3: NPOP-short hairpin negative control (NPOP-sh-NC); N4: NPOP-short hairpin-Mfn2 (NPOP-sh-Mfn2)), and four groups for prolapse (P1−P4, P1: POP-normal saline; P2: POP-untransfected stem cells; P3: POP-sh-NC; P4: POP-sh-Mfn2), respectively. Stem cells were then cultured and isolated. The expression of Mfn2 was inhibited by lentivirus transfection, and the stem cells were injected into the uterosacral ligament of the rats in each group. The expression levels of Mfn2 and procollagen 1A1/1A2/3A1 in the uterosacral ligaments of the rats were observed at 0, 7, 14, and 21 days after injection. Results: Compared to the rats in the NPOP group, the POP rats had significant prolapse. The Mfn2 expression in the uterosacral ligaments of the POP rats was significantly increased (p < 0.05, all), and the expression of procollagen 1A1/1A2/3A1 was significantly decreased (p < 0.001, all). The POP rat model maintained the same trend after 21 days (without stem cell injection). At day 14, compared to the rats in the N1 group, the Mfn2 expression in the uterosacral ligament of the rats in the N4 group was significantly decreased (p < 0.05, all), and the expression of procollagens was significantly increased (p < 0.05, all). Similarly, compared to the rats in the P1 group, the Mfn2 expression in the uterosacral ligament of the rats in the P4 group was significantly decreased (p < 0.05, all), and the expression of procollagens was significantly increased (p < 0.05, all). Similarly, on day 21, the Mfn2 mRNA and protein expression in the uterosacral ligament of the POP and NPOP rats was significantly decreased (p < 0.05, all), and the expression of procollagens was significantly increased (p < 0.05, all) in the rats in the sh-Mfn2 group (N4, P4) compared to the rats in the saline group (N1, P1). Conclusions: The downregulation of Mfn2 expression by stem cells decreased the expression of Mfn2 and increased the expression of procollagen1A1/1A2/3A1 in the uterosacral ligament of the POP rats; this effect was significant 14−21 days after the injection. Thus, Mfn2 may be a new target for POP control.

Curcumin reduces apoptosis and promotes osteogenesis of human periodontal ligament stem cells under oxidative stress in vitro and in vivo

AIMS

Human periodontal ligament stem cells (hPDLSCs) tether the teeth to the surrounding bone and are considered as major functional stem cells responsible for regeneration of the alveolar bone and periodontal ligament tissue. However, the outcome of stem cell regenerative therapy is affected by the survival rate and their differentiation potential of transplanted cells. This is primarily because of local oxidative stress and chronic inflammation at the transplantation site. Therefore, our study aimed to explore whether a natural antioxidant, curcumin could increase the tissue regeneration ability of transplanted hPDLSCs.

MAIN METHODS

A hydrogen peroxide environment and a rat cranial bone defect model were built to mimic the oxidative stress conditions in vitro and in vivo, respectively. We evaluated the effect of curcumin on oxidative status, apoptosis, mitochondrial function and osteogenic differentiation of H2O2-stimulated hPDLSCs in vitro. We also measured the effect of curcumin on cell viability and bone repair ability of transplanted hPDLSCs in vivo.

KEY FINDINGS

Our data showed that curcumin enhanced cell proliferation, reduced the reactive oxygen species (ROS) levels and apoptosis, maintained the standard mitochondrial structure and function, and promoted osteogenic differentiation of H2O2-stimulated hPDLSCs. The extracellular regulated protein kinases 1/2 (Erk1/2) signaling pathway was determined to be involved in the osteogenic differentiation of the H2O2-stimulated hPDLSCs. Moreover, curcumin enhanced the viability and the bone repair ability of hPDLSCs in vivo.

SIGNIFICANCE

Curcumin reduced apoptosis and promoted osteogenesis of the hPDLSCs under oxidative stress, and might therefore have a potential clinical use with respect to tissue regeneration.

Differential gene expression in skin RNA of horses affected with degenerative suspensory ligament desmitis

BACKGROUND

Equine degenerative suspensory ligament desmitis (DSLD) is a systemic connective tissue disorder first identified in Peruvian Paso horses but afflicting other horse breeds as well. Inappropriate accumulation of proteoglycans in connective tissues, most prominently in tendons and ligaments, leads to progressive and debilitating lameness and pain. It is largely unknown what drives the overproduction of proteoglycans, but our previous studies suggest involvement of bone morphogenetic protein 2 (BMP2), a member of the transforming growth factor-β (TGFβ) family, impacting synthesis of proteoglycans. To identify potential players in pathogenesis of DSLD a new approach utilizing next generation sequencing was undertaken.

METHODS

Next generation sequencing was performed using RNA extracted from skin biopsies of six control Peruvian Pasos and six horses with DSLD (4 Peruvian Pasos and 2 warmbloods). The CuffDiff result sets were validated with algorithms used to run them. This was based on the determined false discovery rates derived from the P values adjusted for multiple testing for any given result.

RESULTS

Bioinformatics analysis of transcriptomes revealed differential expression of over 1500 genes, including increased expression of genes for several growth factors (most prominently BMP2, FGF5, CTGF, many members of the EGF family), and mediators of signaling (Fos, Myc, MAPK system), and keratins. Two genes encoding for enzymes involved in synthesis of hyaluronan were also overexpressed. Gene expression was decreased for protein cores of many proteoglycans, several growth factors, most collagens, and many peptides with immune function.

CONCLUSIONS

The overexpression of BMP2 correlates well with our previous data. However, the decrease in expression of numerous proteoglycans was unexpected. A mutation in a gene of a less characterized proteoglycan and/or glycosyltransferase with subsequent increased production of hyaluronan and/or a proteoglycan(s) undetected in our study could account for the systemic proteoglycan deposition. Decreased collagen gene expression indicates abnormal connective tissue metabolism. The increased expression of keratin genes and FGF5 supports reports of skin abnormalities in DSLD. Underexpression of immune function genes corresponds with lack of inflammation in DSLD tissues. Finally, though the proteoglycan and/or glycosaminoglycan abundant in DSLD has not been identified, we validated our previous data, including overexpression of BMP2, and systemic nature of DSLD due to disturbed metabolism of the extracellular matrix.

RNA-seq in Skeletal Biology

PURPOSE OF REVIEW

The goal of this paper is to review state-of-the-art transcriptome profiling methods and their recent applications in the field of skeletal biology.

RECENT FINDINGS

Next-generation sequencing of mRNA (RNA-seq) methods have been established and routinely used in skeletal biology research. RNA-seq has led to the identification of novel genes and transcription factors involved in skeletal development and disease, through its application in small and large animal models, as well as human tissue and cells. With the availability of advanced techniques such as single-cell RNA-seq, novel cell types in skeletal tissues are being identified. As the sequencing technologies are rapidly evolving, the exciting discoveries supported by transcriptomics will continue to emerge and improve our understanding of the biology of the skeleton.

Substrate stiffness- and topography-dependent differentiation of annulus fibrosus-derived stem cells is regulated by Yes-associated protein

Annulus fibrosus (AF) tissue engineering has attracted increasing attention as a promising therapy for degenerative disc disease (DDD). However, regeneration of AF still faces many challenges due to the tremendous complexity of this tissue and lack of in-depth understanding of the structure-function relationship at cellular level within AF is highly required. In light of the fact that AF is composed of various types of cells and has gradient mechanical, topographical and biochemical features along the radial direction. In this study, we aimed to achieve directed differentiation of AF-derived stem cells (AFSCs) by mimicking the mechanical and topographical features of native AF tissue. AFSCs were cultured on four types of electrospun poly(ether carbonate urethane)urea (PECUU) scaffolds with various stiffness and fiber size (soft, small size; stiff, small size; soft, large size and stiff, large size). The results show that with constant fiber size, the expression level of the outer AF (oAF) phenotypic marker genes in AFSCs increased with the scaffold stiffness, while that of inner AF (iAF) phenotypic marker genes showed an opposite trend. When scaffold stiffness was fixed, the expression of oAF phenotypic marker genes in AFSCs increased with fiber size. While the expression of iAF phenotypic marker genes decreased. Such substrate stiffness- and topography-dependent changes of AFSCs was in accordance with the genetic and biochemical distribution of AF tissue from the inner to outer regions. Further, we found that the Yes-associated protein (YAP) was translocated to the nucleus in AFSCs cultured with increasing stiffness and fiber size of scaffolds, yet it remained mostly phosphorylated and cytosolic in cells on soft scaffolds with small fiber size. Inhibition of YAP down-regulated the expression of tendon/ligament-related genes, whereas expression of the cartilage-related genes was upregulated. The results illustrate that matrix stiffness is a potent regulator of AFSC differentiation. Moreover, we reveal that fiber size of scaffolds induced changes in cell adhesions and determined cell shape, spreading area, and extracellular matrix expression. In all, both mechanical property and topography features of scaffolds regulate AFSC differentiation, possibly through a YAP-dependent mechanotransduction mechanism. STATEMENT OF SIGNIFICANCE: Physical cues such as mechanical properties, topographical and geometrical features were shown to profoundly impact the growth and differentiation of cultured stem cells. Previously, we have found that the differentiation of annulus fibrosus-derived stem cells (AFSCs) could be regulated by the stiffness of scaffold. In this study, we fabricated four types of poly(ether carbonate urethane)urea (PECUU) scaffolds with controlled stiffness and fiber size to explore the potential of induced differentiation of AFSCs. We found that AFSCs are able to present different gene expression patterns simply as a result of the stiffness and fiber size of scaffold material. This work has, for the first time, demonstrated that larger-sized and higher-stiffness substrates increase the amount of vinculin assembly and activate YAP signaling in pre-differentiated AFSCs. The present study affords an in-depth comprehension of materiobiology, and be helpful for explain the mechanism of YAP mechanosensing in AF in response to biophysical effects of materials.

In Situ Detection of Degraded and Denatured Collagen via Triple Helical Hybridization: New Tool in Histopathology

Degraded and denatured collagens are useful markers for physiological events (e.g., bone formation and aging) and pathologic conditions (e.g., cancer, arthritis, and fibrosis). Here we describe histological staining of such collagens using fluorescent collagen hybridizing peptide that can specifically bind to collagen strands by folding into triple helix. The method can report the amount of denatured collagen and/or collagen remodeling activity in tissues via localized fluorescence intensity and can be used in conjunction with conventional staining agents. The collagen hybridizing peptide probes can be used across species and collagen types, providing a versatile tool not only for pathology and developmental biology but also histology-based disease diagnosis, staging, and therapeutic screening.

Understanding Tendons: Lessons from Transgenic Mouse Models

Tendons and ligaments are connective tissues that have been comparatively less studied than muscle and cartilage/bone, even though they are crucial for proper function of the musculoskeletal system. In tendon biology, considerable progress has been made in identifying tendon-specific genes (Scleraxis, Mohawk, and Tenomodulin) in the past decade. However, besides tendon function and the knowledge of a small number of important players in tendon biology, neither the ontogeny of the tenogenic lineage nor signaling cascades have been fully understood. This results in major drawbacks in treatment and repair options following tendon degeneration. In this review, we have systematically evaluated publications describing tendon-related genes, which were studied in depth and characterized by using knockout technologies and the subsequently generated transgenic mouse models (Tg) (knockout mice, KO). We report in a tabular manner, that from a total of 24 tendon-related genes, in 22 of the respective knockout mouse models, phenotypic changes were detected. Additionally, in some of the models it was described at which developmental stages these changes appeared and progressed. To summarize, only loss of Scleraxis and TGFβ signaling led to severe tendon developmental phenotypes, while mice deficient for various proteoglycans, Mohawk, EGR1 and 2, and Tenomodulin presented mild phenotypes. These data suggest that the tendon developmental system is well organized, orchestrated, and backed up; this is even more evident among the members of the proteoglycan family, where the compensatory effects are much clearer. In future, it will be of great importance to discover additional master tendon transcription factors and the genes that play crucial roles in tendon development. This would improve our understanding of the genetic makeup of tendons, and will increase the chances of generating tendon-specific drugs to advance overall treatment strategies.

Extracellular Matrix Expression and Production in Fibroblast-Collagen Gels: Towards an In Vitro Model for Ligament Wound Healing

Ligament wound healing involves the proliferation of a dense and disorganized fibrous matrix that slowly remodels into scar tissue at the injury site. This remodeling process does not fully restore the highly aligned collagen network that exists in native tissue, and consequently repaired ligament has decreased strength and durability. In order to identify treatments that stimulate collagen alignment and strengthen ligament repair, there is a need to develop in vitro models to study fibroblast activation during ligament wound healing. The objective of this study was to measure gene expression and matrix protein accumulation in fibroblast-collagen gels that were subjected to different static stress conditions (stress-free, biaxial stress, and uniaxial stress) for three time points (1, 2 or 3 weeks). By comparing our in vitro results to prior in vivo studies, we found that stress-free gels had time-dependent changes in gene expression (col3a1, TnC) corresponding to early scar formation, and biaxial stress gels had protein levels (collagen type III, decorin) corresponding to early scar formation. This is the first study to conduct a targeted evaluation of ligament healing biomarkers in fibroblast-collagen gels, and the results suggest that biomimetic in-vitro models of early scar formation should be initially cultured under biaxial stress conditions.

Myo/Nog cells are present in the ciliary processes, on the zonule of Zinn and posterior capsule of the lens following cataract surgery

Myo/Nog cells, named for their expression of MyoD and noggin, enter the eye during early stages of embryonic development. Their release of noggin is critical for normal morphogenesis of the lens and retina. Myo/Nog cells are also present in adult eyes. Single nucleated skeletal muscle cells designated as myofibroblasts arise from Myo/Nog cells in cultures of lens tissue. In this report we document the presence of Myo/Nog cells in the lens, ciliary body and on the zonule of Zinn in mice, rabbits and humans. Myo/Nog cells were rare in all three structures. Their prevalence increased in the lens and ciliary body of rabbits 24 h following cataract surgery. Rabbits developed posterior capsule opacification (PCO) within one month of surgery. The number of Myo/Nog cells continued to be elevated in the lens and ciliary body. Myo/Nog cells containing alpha smooth muscle actin and striated muscle myosin were present on the posterior capsule and overlaid deformations in the capsule. Myo/Nog cells also were present on the zonule fibers and external surface of the posterior capsule. These findings suggest that Myo/Nog contribute to PCO and may use the zonule fibers to migrate between the ciliary processes and lens.

Differential gene expression of extracellular-matrix-related proteins in the vaginal apical compartment of women with pelvic organ prolapse

INTRODUCTION AND HYPOTHESIS

Pelvic organ prolapse (POP) is a multifactorial disorder that impairs the quality of life (QoL) of older women in particular. The purpose of this study was to elucidate the pathogenesis of POP by focusing on the extracellular matrix (ECM).

METHODS

Patients were classified into two groups-with or without cervical elongation-using the POP quantification system. Specimens were obtained from 29 women with POP during hysterectomy. The expression of fibulin-5, elastin, integrin β1 (ITGβ1), lysyl oxidase-like protein-1 (LOXL1) and collagen in the vagina, uterosacral ligament, and uterine cervix was investigated by quantitative real-time polymerase chain reaction (RT-PCR) and correlation between gene levels and severity of POP examined. The location of proteins was analyzed using immunohistochemical staining and expression of fibulin-5 protein analyzed by Western blotting.

RESULTS

Fibulin-5 and elastin were mainly expressed in lamina propria and fibromuscular layers of the vagina and uterosacral ligament. Gene levels of fibulin-5 and ITGβ1 in uterosacral ligaments increased with severity of POP in women with cervical elongation, while no correlation was observed in women with a normal cervix. In women with uterine cervical elongation, each ECM-related gene significantly increased with POP staging. Furthermore, fibulin-5 protein also increased in the uterosacral ligament and uterine cervix.

CONCLUSIONS

The severity of POP and gene expression of ECM-related proteins were inversely correlated in vaginal tissue in a normal and elongated cervix. These results suggested that the differing progression of the two types of POP have a relationship with ECM-related protein.

Modulating microfibrillar alignment and growth factor stimulation to regulate mesenchymal stem cell differentiation

The ideal tissue engineering (TE) strategy for ligament regeneration should recapitulate the bone - calcified cartilage - fibrocartilage - soft tissue interface. Aligned electrospun-fibers have been shown to guide the deposition of a highly organized extracellular matrix (ECM) necessary for ligament TE. However, recapitulating the different tissues observed in the bone-ligament interface using such constructs remains a challenge. This study aimed to explore how fiber alignment and growth factor stimulation interact to regulate the chondrogenic and ligamentous differentiation of mesenchymal stem cells (MSCs). To this end aligned and randomly-aligned electrospun microfibrillar scaffolds were seeded with bone marrow derived MSCs and stimulated with transforming growth factor β3 (TGFβ3) or connective tissue growth factor (CTGF), either individually or sequentially. Without growth factor stimulation, MSCs on aligned-microfibers showed higher levels of tenomodulin (TNMD) and aggrecan gene expression compared to MSCs on randomly-oriented fibers. MSCs on aligned-microfibers stimulated with TGFβ3 formed cellular aggregates and underwent robust chondrogenesis, evidenced by increased type II collagen expression and sulphated glycosaminoglycans (sGAG) synthesis compared to MSCs on randomly-oriented scaffolds. Bone morphogenetic protein 2 (BMP2) and type I collagen gene expression were higher on randomly-oriented scaffolds stimulated with TGFβ3, suggesting this substrate was more supportive of an endochondral phenotype. In the presence of CTGF, MSCs underwent ligamentous differentiation, with increased TNMD expression on aligned compared to randomly aligned scaffolds. Upon sequential growth factor stimulation, MSCs expressed types I and II collagen and deposited higher overall levels of collagen compared to scaffolds stimulated with either growth factor in isolation. These findings demonstrate that modulating the alignment of microfibrillar scaffolds can be used to promote either an endochondral, chondrogenic, fibrochondrogenic or ligamentous MSC phenotype upon presentation of appropriate biochemical cues.

STATEMENT OF SIGNIFICANCE

Polymeric electrospun fibers can be tuned to match the fibrillar size and anisotropy of collagen fibers in ligaments, and can be mechanically competent. Therefore, their use is attractive when attempting to tissue engineer the bone-ligament interface. A central challenge in this field is recapitulating the cellular phenotypes observed across the bone-ligament interface. Here we demonstrated that it is possible to direct MSCs seeded onto aligned electrospun fibres towards either a ligamentogenic, chondrogenic or fibrochondrogenic phenotype upon presentation of appropriate biochemical cues. This opens the possibility of using aligned microfibrillar scaffolds that are spatially functionalized with specific growth factors to direct MSC differentiation for engineering the bone-ligament interface.

The effect of estrogen on tendon and ligament metabolism and function

Tendons and ligaments are crucial structures inside the musculoskeletal system. Still many issues in the treatment of tendon diseases and injuries have yet not been resolved sufficiently. In particular, the role of estrogen-like compound (ELC) in tendon biology has received until now little attention in modern research, despite ELC being a well-studied and important factor in the physiology of other parts of the musculoskeletal system. In this review we attempt to summarize the available information on this topic and to determine many open questions in this field.

The role of GPX1 in the pathogenesis of female pelvic organ prolapse

Gestation and delivery can increase intra-abdominal pressure, which are well-known risk factors for Pelvic Organ Prolapse (POP). But the pathogenesis mechanism of POP remains unclear. Our previous research showed that the expression of glutathione peroxidase type 1 (GPX1) decreased in pelvic floor ligaments from POP patients, implying that oxidative stress (OS) may be related to POP. The aim of this study was to figure out the role of GPx1 regulation in the pathogenesis of POP. Women (>45 years) who received hysterectomy surgery were enrolled in this research, identified by screening. We applied mechanical strain of 0μ, 5333 μ to GPX1-overexpressing human uterosacral ligament fibroblasts (hUSLFs) isolated from menopausal women without POP respectively for 4 hours, in order to investigate the changes of cell apoptosis, oxidative status and ECM metabolism when cytomechanics model loaded on GPX1-overexpressing hUSLFs. Comparing with the non-transfection and mock-vehicle groups, we found that GPX1 not only protects hUSLFs from cell apoptosis, oxidative damage, but also improves the remodeling of ECM induced by mechanical stimulation. These results suggested that mechanical strain caused abnormalities of ECM metabolism via OS pathway in hUSLFs, which was involved in the pathogenesis of POP, and that GPx1 played a significant role in regulating mechanical strain induced POP.

The second terminations of the suboccipital muscles: An assistant pivot for the To Be Named Ligament

In the last two decades, many studies have focused on the muscles and dense connective tissues located in the suboccipital region. Our study investigated the existence of the second terminations originating from the suboccipital muscles, and the relationship between the variable types of the To Be Named Ligament (TBNL). Anatomical dissection was performed on 35 head-neck specimens. The existence of the second terminations of the suboccipital muscles was confirmed and various types of the TBNL were observed in this study. The second terminations originated from multiple suboccipital muscles including the rectus capitis posterior minor (RCPmi), rectus capitis posterior major (RCPma) and obliquus capitis inferior (OCI) muscles, merged and terminated at the TBNL. The overall incidence of the second terminations of the suboccipital muscles was 34.29% and it varied among the various suboccipital muscle origins. 28.57% of the second terminations originated from the RCPma; 11.43% was from the RCPmi and 8.57% was from the OCI. Furthermore, there was a significant relationship between the existence of second terminations and the particular type of the TBNL. 95% of the arcuate type of the TBNL was accompanied with the second terminations which attached to their turning part, whereas only 10% of all the radiate type of the TBNL was accompanied with the second terminations. This study for the first time described the second terminations originating from multiple suboccipital muscles and demonstrated the relationship with the various types of the TBNL. We speculated that the second terminations maintain the arcuate TBNL and transfer tensile forces to the Myodural Bridge (MDB), thereby modulating the physiological functions of the MDB.

Two tissue-resident progenitor lineages drive distinct phenotypes of heterotopic ossification

Fibrodysplasia ossificans progressiva (FOP), a congenital heterotopic ossification (HO) syndrome caused by gain-of-function mutations of bone morphogenetic protein (BMP) type I receptor ACVR1, manifests with progressive ossification of skeletal muscles, tendons, ligaments, and joints. In this disease, HO can occur in discrete flares, often triggered by injury or inflammation, or may progress incrementally without identified triggers. Mice harboring an Acvr1R206H knock-in allele recapitulate the phenotypic spectrum of FOP, including injury-responsive intramuscular HO and spontaneous articular, tendon, and ligament ossification. The cells that drive HO in these diverse tissues can be compartmentalized into two lineages: an Scx+ tendon-derived progenitor that mediates endochondral HO of ligaments and joints without exogenous injury, and a muscle-resident interstitial Mx1+ population that mediates intramuscular, injury-dependent endochondral HO. Expression of Acvr1R206H in either lineage confers aberrant gain of BMP signaling and chondrogenic differentiation in response to activin A and gives rise to mutation-expressing hypertrophic chondrocytes in HO lesions. Compared to Acvr1R206H, expression of the man-made, ligand-independent ACVR1Q207D mutation accelerates and increases the penetrance of all observed phenotypes, but does not abrogate the need for antecedent injury in muscle HO, demonstrating the need for an injury factor in addition to enhanced BMP signaling. Both injury-dependent intramuscular and spontaneous ligament HO in Acvr1R206H knock-in mice were effectively controlled by the selective ACVR1 inhibitor LDN-212854. Thus, diverse phenotypes of HO found in FOP are rooted in cell-autonomous effects of dysregulated ACVR1 signaling in nonoverlapping tissue-resident progenitor pools that may be addressed by systemic therapy or by modulating injury-mediated factors involved in their local recruitment.

Relaxin Receptor RXFP1 and RXFP2 Expression in Ligament, Tendon, and Shoulder Joint Capsule of Rats

Numerous musculoskeletal disorders are caused by thickened ligament, tendon stiffness, or fibrosis of joint capsule. Relaxin, a peptide hormone, can exert collagenolytic effect on ligamentous and fibrotic tissues. We hypothesized that local injection of relaxin could be used to treat entrapment neuropathy and adhesive capsulitis. Because hormonal effect depends on the receptor of the hormone on the target cell, it is important to confirm the presence of such hormonal receptor at the target tissue before the hormone therapy is initiated. The aim of this study was to determine whether there were relaxin receptors in the ligament, tendon, and joint capsular tissues of rats and to identify the distribution of relaxin receptors in these tissues. Transverse carpal ligaments (TCLs), inguinal ligaments, anterior cruciate ligaments (ACLs), Achilles tendons, and shoulder joint capsules were obtained from male Wistar rats. Western blot analysis was used to identify relaxin receptor isoforms RXFP1 and RXFP2. The distribution of relaxin receptors was determined by immunohistochemical staining. The RXFP1 isoform was found in all tissues examined. The RXFP2 isoform was present in all tissues but the TCLs. Its expression in ACLs tissues was relatively weak compared to that in other tissues. Our results revealed that RXFP1 and RXFP2 were distributed in distinctly different patterns according to the type of tissue (vascular endothelial cells, fibroblast-like cells) they were identified.

Microstructure and Mechanical Property of Glutaraldehyde-Treated Porcine Pulmonary Ligament

There is a significant need for fixed biological tissues with desired structural and material constituents for tissue engineering applications. Here, we introduce the lung ligament as a fixed biological material that may have clinical utility for tissue engineering. To characterize the lung tissue for potential clinical applications, we studied glutaraldehyde-treated porcine pulmonary ligament (n = 11) with multiphoton microscopy (MPM) and conducted biaxial planar experiments to characterize the mechanical property of the tissue. The MPM imaging revealed that there are generally two families of collagen fibers distributed in two distinct layers: The first family largely aligns along the longitudinal direction with a mean angle of θ = 10.7 ± 9.3 deg, while the second one exhibits a random distribution with a mean θ = 36.6 ± 27.4. Elastin fibers appear in some intermediate sublayers with a random orientation distribution with a mean θ = 39.6 ± 23 deg. Based on the microstructural observation, a microstructure-based constitutive law was proposed to model the elastic property of the tissue. The material parameters were identified by fitting the model to the biaxial stress-strain data of specimens, and good fitting quality was achieved. The parameter e0 (which denotes the strain beyond which the collagen can withstand tension) of glutaraldehyde-treated tissues demonstrated low variability implying a relatively consistent collagen undulation in different samples, while the stiffness parameters for elastin and collagen fibers showed relatively greater variability. The fixed tissues presented a smaller e0 than that of fresh specimen, confirming that glutaraldehyde crosslinking increases the mechanical strength of collagen-based biomaterials. The present study sheds light on the biomechanics of glutaraldehyde-treated porcine pulmonary ligament that may be a candidate for tissue engineering.

Strategies to engineer tendon/ligament-to-bone interface: Biomaterials, cells and growth factors

Integration between tendon/ligament and bone occurs through a specialized tissue interface called enthesis. The complex and heterogeneous structure of the enthesis is essential to ensure smooth mechanical stress transfer between bone and soft tissues. Following injury, the interface is not regenerated, resulting in high rupture recurrence rates. Tissue engineering is a promising strategy for the regeneration of a functional enthesis. However, the complex structural and cellular composition of the native interface makes enthesis tissue engineering particularly challenging. Thus, it is likely that a combination of biomaterials and cells stimulated with appropriate biochemical and mechanical cues will be needed. The objective of this review is to describe the current state-of-the-art, challenges and future directions in the field of enthesis tissue engineering focusing on four key parameters: (1) scaffold and biomaterials, (2) cells, (3) growth factors and (4) mechanical stimuli.

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.

Urogynaecology: Collagen metabolism in the uterosacral ligaments and vaginal skin of women with uterine prolapse

OBJECTIVE

To compare tissue markers of collagen metabolism in the uterosacral ligaments with those in vaginal tissue in women with uterine prolapse.

DESIGN

Prospective observational experimental study.

SETTING

A tertiary urogynaecology unit.

POPULATION

Women referred for hysterectomy for prolapse or benign gynaecological disease.

METHODS

Matrix metalloproteinase (MMP)-2 and -9 expression, tissue inhibitors of metalloproteinase (TIMP)-2 expression and hydroxyproline content were measured in the uterosacral ligaments and vaginal tissue from 14 women with prolapse compared with 14 controls.

MAIN OUTCOME MEASURES

Levels of MMP, TIMP and hydroxyproline in the uterosacral ligaments and vaginal tissue of women with prolapse and controls.

RESULTS

Fourteen women with prolapse and 14 women without prolapse (controls) were included. A significant increase in pro MMP-2 expression was seen in vaginal tissue from women with prolapse (P < 0.05) but not activated MMP-2, MMP-9 and TIMP-2. For uterosacral ligaments, the differences were not statistically significant. No significant difference in hydroxyproline content was found between control and prolapse in either tissue. Significant correlations exist in expression of pro-MMP-2, activated MMP-2, MMP-9 and TIMP-2 in vaginal tissue with that in uterosacral ligaments.

CONCLUSIONS

Correlations existed between markers of collagen metabolism in the vaginal and uterosacral tissues. This suggests vaginal tissue reflects the endopelvic fascia. The changes which are more pronounced in vaginal tissue may be as a result of prolapse rather than cause.

An immunohistochemical study of the tissue bridging adult spondylolytic defects--the presence and significance of fibrocartilaginous entheses

Introduction Spondylolytic spondylolisthesis is an osseous discontinuity of the vertebral arch that predominantly affects the fifth lumbar vertebra. Biomechanical factors are closely related to the condition. An immunohistochemical investigation of lysis-zone tissue obtained from patients with isthmic spondylolisthesis was performed to determine the molecular composition of the lysis-zone tissue and enable interpretation of the mechanical demands to which the tissue is subject.

METHODS

During surgery, the tissue filling the spondylytic defects was removed from 13 patients. Twelve spondylolistheses were at the L5/S1 level with slippage being less than Meyerding grade II. Samples were methanol fixed, decalcified and cryosectioned. Sections were labelled with a panel of monoclonal antibodies directed against collagens, glycosaminoglycans and proteoglycans.

RESULTS

The lysis-zone tissue had an ordered collagenous structure with distinct fibrocartilaginous entheses at both ends. Typically, these had zones of calcified and uncalcified fibrocartilage labelling strongly for type II collagen and aggrecan. Labelling was also detected around bony spurs that extended from the enthesis into the lysis-zone. The entheses also labelled for types I, III and VI collagens, chondroitin four and six sulfate, keratan and dermatan sulfate, link protein, versican and tenascin.

CONCLUSIONS

Although the gap filled by the lysis tissue is a pathological feature, the tissue itself has hallmarks of a normal ligament-i.e. fibrocartilaginous entheses at either end of an ordered collagenous fibre structure. The fibrocartilage is believed to dissipate stress concentration at the hard/soft tissue boundary. The widespread occurrence of molecules typical of cartilage in the attachment of the lysis tissue, suggests that compressive and shear forces are present to which the enthesis is adapted, in addition to the expected tensile forces across the spondylolysis. Such a combination of tensile, shear and compressive forces must operate whenever there is any opening or closing of the spondylolytic gap.