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.

Ultrastructural and immunocytochemical evaluation of the effects of extracorporeal shock wave treatment in the hind limbs of horses with experimentally induced suspensory ligament desmitis

OBJECTIVE

To evaluate the effects of extracorporeal shock wave therapy (ESWT) on affected ligaments in the hind limbs of horses with experimentally induced suspensory ligament desmitis by use of ultrasonographic, ultrastructural, and immunocytochemical techniques.

ANIMALS

10 horses.

PROCEDURE

Suspensory ligament desmitis was induced in both hind limbs of each horse by use of 2 collagenase injections (administered 2 weeks apart) in each suspensory ligament. Two weeks after the second injection, the right hind limb of each horse was treated with ESWT (3 treatments at 3-week intervals); the left hind limb was not treated (control limb). Periodically during the study, the healing process was monitored ultrasonographically and the proportions of ligaments affected with lesions were assessed. Four weeks after the last ESWT treatment, biopsy specimens were collected from all ligaments for ultrastructural evaluation and immunocytochemical analysis of transforming growth factor beta-1.

RESULTS

The difference in the proportion of the lesion-affected ligament between ESWT-treated and control limbs was significant (P < 0.05) from 3 weeks after the second ESWT treatment to the end of the study. Compared with control ligaments, ESWT-treated ligaments had more small, newly formed collagen fibrils and greater expression of transforming growth factor beta-1 4 weeks after the last ESWT treatment was administered.

CONCLUSIONS AND CLINICAL RELEVANCE

Results have indicated that ESWT appears to facilitate the healing process in horses with experimentally induced hind limb suspensory ligament desmitis.

Male IL-6 gene knock out mice developed more advanced osteoarthritis upon aging

OBJECTIVE

Interleukin-6 (IL-6) is expressed in osteoarthritic joints but its function in osteoarthritis (OA) is unknown. To study this, spontaneous and experimental OA were evaluated in IL-6 deficient (IL-6(-/-)) mice.

DESIGN

Histology of knees of 18-23-month-old wild type (wt) and IL-6(-/-) mice was compared for signs of OA. Cartilage proteoglycan (PG) density was measured by image analysis on safranin-O stained whole knee sections. Chondrocyte PG synthesis was measured ex vivo by (35)S-sulfate incorporation. Knee bone mineral density (BMD) was measured by dual energy x-ray absorptiometry. In young mice (3 months), OA was induced by intra-articular injection of collagenase.

RESULTS

The incidence of extensive cartilage loss at both lateral and medial sides was markedly higher in old IL-6(-/-) males, but not in females, as compared to their wt controls. Compared to age-matched wt mice, reduced ex vivo PG synthesis was found during aging in IL-6(-/-) males, without affecting their cartilage PG density. IL-6(-/-) males showed more extensive extracellular matrix deposition in the collateral ligaments and subchondral bone sclerosis, predominantly at the medial side. Total knee BMD decreased more in IL-6(-/-) (-23%) than in wt (-10%) males during aging. Collagenase-induced OA showed a similar degree of joint pathology in both strains, implying that OA susceptibility was not different at younger age.

CONCLUSIONS

Upon aging, IL-6(-/-) male mice developed more severe spontaneous OA. Reduced PG synthesis and BMD values might be indicative for an impaired repair response in IL-6(-/-) mice. This suggests a protective role for IL-6 in age-related OA in male mice.

The promyelotic leukemia zinc finger promotes osteoblastic differentiation of human mesenchymal stem cells as an upstream regulator of CBFA1

Ossification of the posterior longitudinal ligament of the spine (OPLL) is the leading cause of myelopathy in Japan and is diagnosed by ectopic bone formation in the paravertebral ligament. OPLL is a systemic high bone mass disease with a strong genetic background. To detect genes relevant to the pathogenesis of OPLL, we performed a cDNA microarray analysis of systematic gene expression profiles during the osteoblastic differentiation of ligament cells from OPLL patients (OPLL cells), patients with a disorder called ossification of yellow ligament (OYL), and non-OPLL controls together with human mesenchymal stem cells (hMSCs) after stimulating them with osteogenic differentiation medium (OS). Twenty-four genes were up-regulated during osteoblastic differentiation in OPLL cells. Zinc finger protein 145 (promyelotic leukemia zinc finger or PLZF) was one of the highly expressed genes during osteoblastic differentiation in all the cells examined. We investigated the roles of PLZF in the regulation of osteoblastic differentiation of hMSCs and C2C12 cells. Small interfering RNA-mediated gene silencing of PLZF resulted in a reduction in the expression of osteoblast-specific genes such as the alkaline phosphatase, collagen 1A1 (Col1a1), Runx2/core-binding factor 1 (Cbfa1), and osteocalcin genes, even in the presence of OS in hMSCs. The expression of PLZF was unaffected by the addition of bone morphogenetic protein 2 (BMP-2), and the expression of BMP-2 was not affected by PLZF in hMSCs. In C2C12 cells, overexpression of PLZF increased the expression of Cbfa1 and Col1a1; on the other hand, the overexpression of CBFA1 did not affect the expression of Plzf. These findings indicate that PLZF plays important roles in early osteoblastic differentiation as an upstream regulator of CBFA1 and thereby might participate in promoting the ossification of spinal ligament cells in OPLL patients.

Identification and characterization of an L-type Cav1.2 channel in spiral ligament fibrocytes of gerbil inner ear

Intracellular free Ca2+ levels are critical to the activity of BK channels in inner ear type I spiral ligament fibrocytes. However, the mechanisms for regulating intracellular Ca2+ levels in these cells are currently poorly understood. Using patch-clamp technique, we have identified a voltage-dependent L-type Ca2+ channel in type I spiral ligament fibrocytes cultured from gerbil inner ear. With 10 mM Ba2+ as the conductive cation, an inwardly rectifying current was elicited with little inactivation by membrane depolarization. The voltage activation threshold and the half-maximal voltage activation were -40 and -6 mV, respectively. This inward whole-cell current reached its peak at around 10 mV of membrane potential. The amplitude of the peak current varied among cells ranging from 50 to 274 pA with an average of 132.4 +/- 76.2 pA (n = 19); 10(-6) M nifedipine significantly inhibited the inward currents by 90.3 +/- 1.2% (n = 11). RT-PCR analysis revealed that cultured type I spiral ligament fibrocytes express the alpha1C isoform of the L-type Ca2+ channels encoded by the Cav1.2 gene. The expression of this channel in gerbil inner ear was confirmed by RT-PCR analysis using freshly isolated spiral ligament tissues. The Cav1.2 channel may function in conjunction with a previously identified intracellular Ca-ATPase (SERCA) to regulate intracellular free Ca2+ levels in type I spiral ligament fibrocytes, and thus modulate BK channel activity in these cells.

Changes in gonadal steroid receptors in the cardinal ligaments of prolapsed uteri: immunohistomorphometric data

BACKGROUND

The precise mechanism of uterine prolapse is poorly understood. This immunohistochemical study was performed on paraffin-embedded sections of the cardinal ligaments in an attempt to evaluate the differential expression of gonadal steroid receptors in human cardinal ligaments of prolapsed uteri compared with non-prolapsed controls.

METHODS

Specimens from women with pelvic organ prolapse (POP) stage III (n = 33), together with the appropriate controls (n = 25), were stained for estrogen receptor alpha (ERalpha), ERbeta, progesterone receptor (PR), androgen receptor (AR) and Ki-67. The control materials were samples of the cardinal ligaments obtained from pre- and post-menopausal women with no prolapse, who were not using hormonal therapy. RESULTS The prolapsed ligaments expressed 1.5-2.5 times more ERalpha-positive cells (statistically significant in post-menopausal women not taking HRT, P < 0.001), a 3-4 times greater percentage of AR-positive cells (P = 0.004 and P = 0.008 in pre-menopausal and post-menopausal women not taking HRT, respectively) and twice the percentage of PR-positive cells (statistically significant in the pre-menopausal group, P = 0.03) compared with the no prolapse group. Expression of ERbeta was twice as high in the ligaments of pre-menopausal women with no prolapse compared with those with prolapse (P = 0.02), and no significant difference was found in the post-menopausal groups. The use of HRT was significantly associated with low AR and high PR expression. Ki-67 expression was not detected in these specimens.

CONCLUSIONS

The clearly discernible levels of expression of ERalpha, ERbeta, AR and PR in the prolapsed cardinal ligaments may suggest a relationship to the process of tissue stretch 'trauma', rather than an effect of the menopausal status, HRT use or cell proliferation. The use of HRT in post-menopausal women appears to offset some of the changes observed with the prolapse.

Human bone marrow stromal cell and ligament fibroblast responses on RGD-modified silk fibers

Adhesion, spreading, proliferation, and collagen matrix production of human bone marrow stromal cells (BMSCs) on an RGD-modified silk matrix was studied. Anterior cruciate ligament fibroblasts (ACLFs) were used as a control cell source. Scanning electron microscopy (SEM) and MTT analyses demonstrated that the modified silk matrices support improved BMSC and ACLF attachment and show higher cell density over 14 days in culture when compared with the non-RGD-modified matrices. Collagen type I transcript levels (at day 7) and content (at day 14) was significantly higher on the RGD-modified substrate than on the nonmodified group. The ability of RGD-coupled silk matrices to support BMSC attachment, which leads to higher cell density and collagen matrix production in vitro, combined with mechanical, fatigue, and biocompatibility properties of the silk protein matrix, suggest potential for use of this biomaterial for tissue engineering.

Changes in extracellular matrix proteins in the cardinal ligaments of post-menopausal women with or without prolapse: a computerized immunohistomorphometric analysis

BACKGROUND

The precise mechanism of uterine prolapse is poorly understood. There is evidence to suggest that abnormalities of connective tissue structure or its repair mechanism may predispose women to prolapse.

METHODS AND RESULTS

This immunohistochemical study was performed on paraffin-embedded sections of the cardinal ligaments in an attempt to evaluate differences in the expression of extracellular matrix (ECM) proteins: collagen I, collagen III, elastin and tenascin, in the cardinal ligaments of prolapsed compared to non-prolapsed uteri. There appear to be discernable differences in the level of expression of ECM proteins in prolapsed compared to non-prolapsed cardinal ligaments. We found that the ligaments of the prolapsed uteri are characterized by a higher expression of collagen III and tenascin, and lower quantities of elastin. It appears that the use of HRT in post-menopausal women reverses some of the changes observed in cases of prolapse. Collagen I expression is directly related to the age and menopausal status rather than to prolapse.

CONCLUSIONS

In contrast to collagen I, our findings clearly indicate that collagen III expression is directly related to the presence of prolapse rather than age or menopausal status and is suppressed with the use of HRT. The pattern of change may fit a picture of healing phase of traumatized tissue as evidenced by the raised tenascin expression. The trauma itself may have been initiated by events such as childbirth, and that the lack of estrogen following the menopause results in decompensation. In spite of ameliorating some of the changes such as suppression of collagen III expression, treatment with estrogen falls short of rectifying the expression of other necessary proteins. If these mechanisms can be elucidated, a supplementary drug therapy may help along with estrogens to rebuild these ligaments.

MAGP-2 has multiple binding regions on fibrillins and has covalent periodic association with fibrillin-containing microfibrils

The interactions of microfibril-associated glycoprotein (MAGP)-2 have been investigated with fibrillins and fibrillin-containing microfibrils. Solid phase binding assays were conducted with recombinant fragments covering fibrillin-1 and most of fibrillin-2. MAGP-2, and its structure relative MAGP-1, were found to bind two fragments spanning the N-terminal half of fibrillin-1 and an N-terminal fragment of fibrillin-2. Blocking experiments indicated that MAGP-2 had a binding site(s) close to the N terminus of the fibrillin-1 molecule that was distinct from that for MAGP-1 and an additional, more central binding site(s) that may be shared by the two MAGPs. Immunogold labeling of developing nuchal ligament tissue showed that MAGP-2 had regular covalent and periodic (about 56 nm) association with fibrillin-containing microfibrils of elastic fibers in this tissue. Further analysis of isolated microfibrils indicated that MAGP-2 was attached at two points along the microfibril substructure, "site 1" on the "beads" and "site 2" at the "shoulder" of the interbead region close to where the two "arms" fuse. In contrast, MAGP-1 was located only on the beads. Comparison of the MAGP-2 binding data with known fibrillin epitope maps of the microfibrils showed that site 1 correlated with the N-terminal MAGP-2 binding region, and site 2 correlated with the second, more central, MAGP-2 binding region on the fibrillin-1 molecule. Of particular note, immunolabeling at site 2 was markedly decreased, relative to that at site 1, on extended microfibrils with bead-to-bead periods over 90 nm, suggesting that site 2 may move toward the beads when the microfibril is stretched. The study points to MAGP-2 being an integral component of some populations of fibrillin-containing microfibrils. Moreover, the identification of multiple MAGP-binding sequences on fibrillins supports the concept that MAGPs may function as molecular cross-linkers, stabilizing fibrillin monomers in folded conformation within or between the microfibrils, and thus MAGPs may be implicated in the modulation of the elasticity of these structures.

Age-related changes of elements and relationships among elements in human tendons and ligaments

To elucidate compositional changes of the tendons and ligaments with aging, the authors investigated age-related changes of element contents in the insertion tendons of the biceps brachii muscle, central tendons of the diaphragma, Achilles' tendons, posterior longitudinal ligaments (PLLs) of the cervical spine, ligamenta capitum femorum, and anterior cruciate ligaments. After ordinary dissections by medical students, the three tendons and three ligaments were resected and element contents were determined by inductively coupled plasma-atomic emission spectrometry. It was found that the elements, such as Ca, P, S, Mg, Na, Zn, and Fe, did not change significantly in the three tendons and two ligaments with aging, except for the PLLs where Ca and Mg increased significantly with aging and Fe decreased significantly with aging. With regard to the relationships among elements, the common finding that there were significant correlations between Ca and P contents and between Ca and Mg contents was obtained in the three ligaments. Likewise, the common finding that there was a significant correlation between Ca and Mg contents was obtained in the three tendons. Regarding the relationship between Ca and P contents, the three tendons were different from the three ligaments.

Dexamethasone induces human spinal ligament derived cells toward osteogenic differentiation

Ossification of spinal ligament is characterized by heterotopic bone formation in the spinal ligaments that are normally composed of fibrous tissues. The pathogenesis of ossification of spinal ligament has been suggested to be associated with osteogenic differentiation of the spinal ligament cells. In order to address this hypothesis, cells derived from human spinal ligament were investigated for their osteogenic potential by the treatment of dexamethasone in vitro. Yellow ligaments were obtained from patients with spinal disorders except ossification of spinal ligament during surgery, and the adhering tissues were removed completely. Most of the ligament cells treated with vehicle exhibited a fibroblast-like spindle shape, while the dexamethasone-treated cells acquired a polygonal morphology. Growth of the ligament cells was suppressed by dexamethasone at a high concentration. Some of the vehicle treated-cells were alkaline phosphatase-positive, and dexamethasone increased the alkaline phosphatase-positive cells and alkaline phosphatase activity in the cells. Northern blot analysis demonstrated that mRNAs expression of pro-alpha1(I) collagen and alkaline phosphatase were promoted by dexamethasone. Analysis by reverse transcription-polymerase chain reaction showed that expression of osteocalcin mRNA was detected in the dexamethasone-treated cells but not in the vehicle-treated cells, and dexamethasone-induced osteocalcin mRNA expression was promoted by 1,25-dihydroxyvitamin D(3). Finally, mineralization of extracellular matrix in the cells was induced by the presence of dexamethasone and 1,25-dihydroxyvitamin D(3). These results suggest for the first time that dexamethasone has a possible involvement in the osteoblastic differentiation of human spinal ligament cells.

Mechanical characterization of collagen fibers and scaffolds for tissue engineering

Engineered tissues must utilize scaffolding biomaterials that support desired cellular functions and possess or can develop appropriate mechanical characteristics. This study assessed properties of collagen as a scaffolding biomaterial for ligament replacements. Mechanical properties of extruded bovine achilles tendon collagen fibers were significantly affected by fiber diameter, with smaller fibers displaying higher tangent moduli and peak stresses. Mechanical properties of 125 micrometer-diameter extruded fibers (tangent modulus of 359.6+/-28.4MPa; peak stress of 36.0+/-5.4MPa) were similar to properties reported for human ligaments. Scaffolds of extruded fibers did not exhibit viscoelastic creep properties similar to natural ligaments. Collagen fibers from rat tail tendon (a well-studied comparison material) displayed characteristic strain-softening behavior, and scaffolds of rat tail fibers demonstrated a non-intuitive relationship between tangent modulus and specimen length. Composite scaffolds (extruded collagen fibers cast within a gel of Type I rat tail tendon collagen) were maintained with and without fibroblasts under standard culture conditions for 25 days; cell-incorporated scaffolds displayed significantly higher tangent moduli and peak stresses than those without cells. Because tissue-engineered products must possess appropriate mechanical as well as biological/chemical properties, data from this study should help enable the development of improved tissue analogues.

Mineralization of stylohyoid ligament complex in patients with temporomandibular disorders and asymptomatic individuals: a comparative study

The incidence of mineralization of the stylohyoid ligament complex, according to radiographic findings, was analysed in a group of patients with temporomandibular disorders (TMD), and compared with that of a control group of asymptomatic individuals (AI). Both groups were similar considering the prevalence of the female gender as well as the distribution of cases according to age. 'Elongated' was the most frequent radiographic appearance in both groups; 'partially mineralized' was the most frequent radiographic pattern in the TMD group; and the lower ramus was the most frequent location of mineralization in both groups. When comparing between groups and according to each class, there was only one significant difference in radiographic appearance, 'pseudoarticulated' being more frequent in the TMD group. We can conclude that the occurrence and characteristics of mineralization of stylohyoid ligament complex were similar in TMD patients and AIs.

Covalent and non-covalent interactions of betaig-h3 with collagen VI. Beta ig-h3 is covalently attached to the amino-terminal region of collagen VI in tissue microfibrils

Transforming growth factor-beta induced gene-h3 (betaig-h3) was found to co-purify with collagen VI microfibrils, extracted from developing fetal ligament, after equilibrium density gradient centrifugation under both nondenaturing and denaturing conditions. Analysis of the collagen VI fraction from the non-denaturing gradient by gel electrophoresis under non-reducing conditions revealed the present of a single high molecular weight band that immunostained for both collagen VI and betaig-h3. When the fraction was analyzed under reducing conditions, collagen VI alpha chains and betaig-h3 were the only species evident. The results indicated that betaig-h3 is associated with collagen VI in tissues by reducible covalent bonding, presumably disulfide bridges. Rotary shadowing and immunogold staining of the collagen VI microfibrils and isolated tetramers indicated that betaig-h3 was specifically and periodically associated with the double-beaded region of many of the microfibrils and that this covalent binding site was located in or near the amino-terminal globular domain of the collagen VI molecule. Using solid phase and co-immunoprecipitation assays, recombinant betaig-h3 was found to bind both native and pepsin-treated collagen VI but not individual pepsin-collagen VI alpha chains. Blocking experiments indicated that the major in vitro betaig-h3 binding site was located in the pepsin-resistant region of collagen VI. In contrast to the tissue situation, the in vitro interaction had the characteristics of a reversible non-covalent interaction, and the Kd was measured as 1.63 x 10(-8) m. Rotary shadowing of immunogold-labeled complexes of recombinant betaig-h3 and pepsin-collagen VI indicated that the in vitro betaig-h3 binding site was located close to the amino-terminal end of the collagen VI triple helix. The evidence indicates that collagen VI may contain distinct covalent and non-covalent binding sites for betaig-h3, although the possibility that both interactions use the same binding region is discussed. Overall the study supports the concept that betaig-h3 is extensively associated with collagen VI in some tissues and that it plays an important modulating role in collagen VI microfibril function.

Gene therapy and tissue engineering in repair of the musculoskeletal system

Historically, surgeons have sought and used different procedures in order to augment the repair of various skeletal tissues. Now, with the completion of the Human Genome Project, many researchers have turned to gene therapy as a means to aid various ailments. In the orthopedic field, many strides have been made toward using gene therapy and tissue engineering in a clinical setting. In this review, several studies are outlined in different areas that gene therapy has or will influence orthopedic surgery. Gene therapy and tissue engineering can aid in fracture healing and spinal fusions by inducing bone formation, ligamentous repairs by increasing the production of connective tissue fibers, intervertebral disc disease by creating potential replacements, and articular cartilage repairs by providing means to improve cartilage. As we continue to see great contributions, such as the few mentioned here, this field will continue to mature and develop.

Growth and maturational changes in dense fibrous connective tissue following 14 days of rhGH supplementation in the dwarf rat

The purpose of this study was to investigate the impact of recombinant human growth hormone (rhGH) on patella tendon (PT), medial collateral ligament (MCL), and lateral collateral ligament (LCL) on collagen growth and maturational changes in dwarf GH-deficient rats. Twenty male Lewis mutant dwarf rats, 37 days of age, were randomly assigned to Dwarf + rhGH (n = 10) and Dwarf + vehicle (n = 10) groups. The GH group received 1.25 mg rhGH/kg body wt twice daily for 14 days. rhGH administration stimulated dense fibrous connective tissue growth, as demonstrated by significant increases in hydroxyproline specific activity and significant decreases in the non-reducible hydroxylysylpyridinoline (HP) collagen cross-link contents. The increase in the accumulation of newly accreted collagen was 114, 67, and 117% for PT, MCL, and LCL, respectively, in 72 h. These findings suggest that a short course rhGH treatment can affect the rate of new collagen production. However, the maturation of the tendon and ligament tissues decreased 18-25% during the rapid accumulation of de novo collagen. We conclude that acute rhGH administration in a dwarf rat can up-regulate new collagen accretion in dense fibrous connective tissues, while causing a reduction in collagen maturation.

Effects of stimulus with proinflammatory mediators on nitric oxide production and matrix metalloproteinase activity in explants of cranial cruciate ligaments obtained from dogs

OBJECTIVE

To evaluate the origin and degree of activity of nitric oxide (NO) and matrix metalloproteinase (MMP) in explants of cranial cruciate ligaments (CCLs) obtained from dogs and cultured with and without inflammatory activators.

SAMPLE POPULATION

Tissue specimens obtained from 7 healthy adult Beagles that were (mean +/- SD) 4.5 +/- 0.5 years old and weighed 12.5 +/- 0.8 kg.

PROCEDURE

The CCLs were harvested immediately after dogs were euthanatized, and specimens were submitted for explant culture. Cultures were stimulated by incubation with a combination of interleukin-1, tumor necrosis factor-alpha, and lipopolysaccharide, or they were not stimulated. Culture supernatants were examined for production of NO nitrite-nitrate metabolites (NOts) and activity of MMP Cultured specimens were evaluated by use of immunohistochemical analysis to detect activity of inducible NO synthase (iNOS).

RESULTS

All ligament explants produced measurable amounts of NOts. Stimulated cultures produced significantly more NOts after incubation for 24 and 48 hours, compared with nonstimulated cultures. Production of MMP in supernatants after incubation for 48 hours was significantly higher in stimulated cultures than in nonstimulated cultures. Cells with positive staining for iNOS were detected on all slides. Positively stained cells were predominantly chondroid metaplastic. There was a significant difference in intensity of cell staining between stimulated and non-stimulated cultures.

CONCLUSIONS AND CLINICAL RELEVANCE

Explant cultures of intact CCLs obtained from dogs produce iNOS-induced NO. Stimulation of chondroid metaplastic cells in CCL of dogs by use of inflammatory activators can increase production of iNOS, NOts, and MMP.

Spiral ligament pathology in quiet-aged gerbils

The ultrastructure of the spiral ligament was compared in aged and young gerbils to assess the involvement of connective tissues in the lateral wall and particularly the fibrocytes in development of presbyacusis. Pathologic features in fibrocytes of senescent gerbils spanned a wide range reflecting different stages of lateral wall involution. All of the type II, IV and V fibrocytes selectively developed cytosolic vacuoles in an early degenerative phase showing minimal strial involvement. Clear spaces indicative of interstitial edema separated the vacuolated cell bodies and their plasmalemmal processes. As a presumed intermediate phase, profiles of amorphous substance apparently derived from apoptosis/necrosis of type II fibrocytes infiltrated the type II fibrocyte area among nearly normal appearing cells. In cochlear turns with advanced strial degeneration, type II fibrocytes disappeared from the spiral prominence area leaving only type I-like fibrocytes occasionally accompanied by a collagen infiltrate. Type V fibrocytes disappeared similarly from the suprastrial area. The extent of atrophy in type II fibrocytes corresponded in general with that in the neighboring stria vascularis. Age-dependent atrophy in the lateral wall largely spared type I fibrocytes except that they often enclosed discrete amorphous foci lacking organelles. The involution thus affected principally the Na,K-ATPase-positive fibrocytes functioning in active uptake rather than passive conductance of K(+). The vacuolization and degeneration exclusive to ATPase-rich fibrocytes and the associated intercellular edema are interpreted as secondary responses, possibly as a result of impaired diffusion of K(+) through downstream marginal cells.

[Gene therapy in surgical sport medicine]

The application of gene therapy to sports medicine is in its infancy, but it holds much promise as a novel procedure to improve the clinical management of sports injuries. Gene therapy will be particularly useful in initiating and accelerating the repair of cartilage, meniscus, tendon, and ligament. Several growth factors and other cytokines have been identified as important mediators of a successful healing process. Such molecules have promise as novel agents for the treatment of sports injuries, but there is presently no clinically useful way to deliver them. Gene transfer may be used to serve this purpose. Gene therapy functions as a type of local biological drug delivery system. Recent studies have shown the feasibility of transferring marker genes to synovium, chondrocytes, meniscal fibrochondrocytes, tenocytes and ligamental fibroblasts, prompting optimism about the eventual success of this approach.

Donor cell survival and repopulation after intraarticular transplantation of tendon and ligament allografts

The specific cells within ligaments and tendons are important to maintain the unique structural and material properties of these tissues. The use of tendon and ligament allografts with living cells for ligament reconstruction would be desirable assuming that these cells would survive after transplantation and continue to function. We assessed the fate of donor cells in fresh allografts of the patellar and anterior cruciate ligaments after transplantation. The cells in these allografts used to reconstruct the anterior cruciate ligament did not survive. This was demonstrated using a DNA probe technique that clearly distinguished donor cells from host cells in the Spanish goat model. The donor cells were replaced by host cells in a rapid manner. The host cells that repopulated the allografts assumed the histologic similarity to the fibroblasts they replace. Simultaneous full-thickness skin transplants in the same animals were not rejected during the interval of rapid loss of donor DNA from the allografts. The absence of rejection of the skin grafts at the one-week interval suggests that no pre-existing antibody associated with an immune reaction was responsible for the rapid loss of DNA in the allografts. The clinical basis for utilizing intra-articular allografts with living donor cells needs further justification to account for their increased expense, more complicated surgical logistics, and higher potential risk of disease transmission.

Role of the gubernacular bulb in cremaster muscle development of the rat

The role of the gubernaculum during the inguino-scrotal phase of testicular descent remains controversial. Some authors propose involution and eversion while others suggest active migration, although the site of growth is unknown. We aimed to determine whether the gubernacular bulb is actively proliferating or regressing during inguino-scrotal testicular descent in the rat. Gubernacula were removed from Sprague-Dawley rats and congenitally-cryptorchid TS mutant rats. Animals (0, 3, 7, 10, and 11 days of age) were treated with bromodeoxyuridine (BUdR) 2 hr before they were killed. BUdR incorporation into newly synthesized DNA served as a marker of cell division. The gubernacula were histologically processed for hematoxylin-eosin (H&E) and immunoperoxidase staining. Four different areas within the gubernaculum were examined for BUdR-positive cells: area 1: plica gubernaculi (cord); area 2: pars infravaginalis gubernaculi (bulb); area 3: distal part of the cremaster muscle; and area 4: proximal part of the cremaster muscle. The rate of cell division for each of these areas was determined by counting the number of BUdR-positive cells per 100 cells. The highest rate of BUdR labeling in both types of rats was in area 2, which is the tip of the gubernacular bulb, and this was significantly greater (P < 0.0001) than in the gubernacular cord or developing cremaster muscle. The mitotic activity was also noted to be significantly greater (P < 0.0001) at the distal end of the cremaster muscle than at the proximal end. The amount of mitosis decreased significantly (P < 0.01) in areas 2 and 4 of the gubernaculum in Sprague-Dawley rats across the period studied. This trend was not observed in TS rats. Our results suggest that the bulb actively proliferates after birth, with possible differentiation into new cremaster muscle cells. We propose that the bulb is the growing end of the elongating gubernaculum, analogous to the growth of a limb bud.