Elastic fibers of musculoskeletal tissues in bovine Marfan syndrome: a morphometric study.

Bovine Marfan syndrome has all the major pathognomonic, clinical, and pathological features of the human syndrome. To further explore the alterations characterizing Marfan syndrome, musculoskeletal tissues from affected and healthy cattle were subjected to histochemical and histomorphometric analysis. Our findings demonstrated reduced elastic fiber content in the periosteum, capsule, interosseous ligament, and flexor tendons of the metatarsophalangeal joint of affected cattle. The elastic properties of a tissue are supplied by elastic fibers in the extracellular matrix; therefore, their reduced content in articular tissues suggests that these fibers could be functionally incompetent to withstand normal stress, causing a predisposition to joint laxity and dislocation. Moreover, perichondrial-periosteal membranes, which are made of collagen and elastic fibers, are known to affect the growth process of the long bones. The decrease in the number of elastic fibers in these membranes could result in reduced restraint of skeletal growth and explain some skeletal abnormalities of Marfan syndrome (i.e., dolichostenomelic habitus).     

Collagen orientation in periosteum and perichondrium is aligned with preferential directions of tissue growth

A feedback mechanism between different tissues in a growing bone is thought to determine the bone's morphogenesis. Cartilage growth strains the surrounding tissues, eliciting alterations of its matrix, which in turn, creates anisotropic stresses, guiding directionality of cartilage growth. The purpose of this study was to evaluate this hypothesis by determining whether collagen fiber directions in the perichondrium and periosteum align with the preferential directions of long bone growth. Tibiotarsi from chicken embryos across developmental stages were scanned using optical projection tomography (OPT) to assess preferential directions of growth at characteristic sites in perichondrium and periosteum. Quantified morphometric data were compared with two‐photon laser‐scanning microscopy images of the three‐dimensional collagen network in these fibrous tissues. The diaphyseal periosteum contained longitudinally oriented collagen fibers that aligned with the preferential growth direction. Longitudinal growth at both metaphyses was twice the circumferential growth. This concurred with well‐developed circumferential fibers, which covered and were partly interwoven with a dominant network of longitudinally oriented fibers in the outer layer of the perichondrium/periosteum at the metaphysis. Toward both articulations, the collagen network of the epiphyseal surface was randomly oriented, and growth was approximately biaxial. These findings support the hypothesis that the anisotropic architecture of the collagen network, detected in periosteum and perichondrium, concurs with the assessed growth directions. © 2008 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 26:1263–1268, 2008     

Intracellular tension in periosteum/perichondrium cells regulates long bone growth

Perichondrium/periosteum is involved in regulating long bone growth. Long bones grow faster after removal or circumferential division of periosteum. This can be countered by culturing them in conditioned medium from perichondrium/periosteum cells. Because both complete removal and circumferential division are effective, we hypothesized that perichondrium/periosteum cells require an intact environment to release the appropriate soluble factors. More specifically, we propose that this release depends on their ability to generate intracellular tension. This hypothesis was explored by modulating the ability of perichondrium/periosteum cells to generate intracellular tension and monitoring the effect thereof on long bone growth. Perichondrium/periosteum cells were cultured on substrates with different stiffness. The medium produced by these cultures was added to embryonic chick tibiotarsi from which perichondrium/periosteum was either stripped or left intact. After 3 culture days, long bone growth was proportionally related to the stiffness of the substrate on which perichondrium/periosteum cells were grown while they produced conditioned medium. A second set of experiments demonstrated that the effect occurred through expression of a growth‐inhibiting factor, rather than through the reduction of a stimulatory factor. Finally, evidence for the importance of intracellular tension was obtained by showing that the inhibitory effect was abolished when perichondrium/periosteum cells were treated with cytochalasin D, which disrupts the actin microfilaments. Thus, we concluded that modulation of long bone growth occurs through release of soluble inhibitors by perichondrium/periosteum cells, and that the ability of cells to develop intracellular tension through their actin microfilaments is at the base of this mechano‐regulated control pathway. © 2010 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 29:84–91, 2011     

Coil embolization of a gluteal false aneurysm in a patient with Marfan syndrome

The classic cardiovascular complications of Marfan syndrome are annuloaortic ectasia, mitral valve disease, and aortic dissection. These conditions can be explained by a progressive loss of connective tissue elastic fibers of the inner arterial wall that lead to its fragility and distensibility. Other aneurysmal locations have been reported in relation to this condition, though clearly less frequently. We report here the case of a patient with Marfan syndrome who successively had annuloaortic ectasia and Barlow's disease, which were successfully treated in 1987, a false aneurysm on the reimplantation of the right coronary artery that necessitated reintervention in 1992, and a gluteal false aneurysm diagnosed and treated in 1993.     

Opioid peptides and receptors in joint tissues: study in the rat.

Using immunohistochemical and biochemical techniques, the occurrence of endogenous opioid peptides and their receptors in normal rat bone and joint tissues was investigated. Opioid receptors were detected, quantified, and characterized in homogenates from capsule/synovium and periosteum using radioligand binding assays. Receptor binding of the nonselective opioid [3H]naloxone to tissue homogenates was stereospecific and saturable, showing similar characteristics to that of brain tissue, although with lower binding capacities. By immunohistochemistry, the neuronal occurrence of four different enkephalins was demonstrated in synovium, bone marrow, periosteum, and juxta-articular bone, whereas no neuronal dynorphin immunoreactivity was detected. Double-staining studies disclosed that enkephalins coexisted with substance P in primary afferent fibers. The applied techniques can be used to assess changes in the distribution of endogenous opioids and their receptors in joint tissues in conditions associated with pain and inflammation. The endogenous opioid system now demonstrated might be targeted and exploited therapeutically to obtain peripheral control of symptoms in joint disorders.     

Diagnostic power of aortic elastic properties in young patients with Marfan syndrome

BACKGROUND: In patients with Marfan syndrome, progressive aortic dilation implicates a still-unpredictable risk of life-threatening aortic dissection and rupture. We sought to quantify aortic wall dysfunction noninvasively, determine the diagnostic power of various aortic parameters, and establish a diagnostic model for the early detection of aortic abnormalities associated with Marfan syndrome. METHODS: In 19 patients with Marfan syndrome (age, 17.7 +/- 9.5 years) and 19 age- and sex-matched healthy control subjects, computerized ascending and abdominal aortic wall contour analysis with continuous determination of aortic diameters was performed out of transthoracic M-mode echocardiographic tracings. After simultaneous oscillometric blood pressure measurement, aortic elastic properties were determined automatically. RESULTS: The following ascending aortic elastic parameters showed statistically significant differences between the Marfan group and the control group: (1) decreased aortic distensibility ( P < .001), (2) increased wall stiffness index ( P < .01), (3) decreased systolic diameter increase ( P < .01), and (4) decreased maximum systolic area increase ( P < .001). The diagnostic power of all investigated parameters was tested by single logistic regression models. A multiple logistic regression model including solely aortic parameters yielded a sensitivity of 95% and a specificity of 100%. CONCLUSIONS: In young patients with Marfan syndrome, a computerized image-analyzing technique revealed decreased aortic elastic properties expressed by parameters showing high diagnostic power. A multiple logistic regression model including merely aortic parameters can serve as useful predictor for Marfan syndrome.     

Mechanisms of aortic valve incompetence: finite-element modeling of Marfan syndrome.

OBJECTIVES: Progressive aortic root dilatation and an increased aortic root elastic modulus have been documented in persons with Marfan syndrome. To examine the effect of aortic root dilatation and increased elastic modulus on leaflet stress, strain, and coaptation, we used a finite-element model. METHODS: The normal model incorporated the geometry, tissue thickness, and anisotropic elastic moduli of normal human roots and valves. Four Marfan models were evaluated, in which the diameter of the aortic root was dilated by 5%, 15%, 30%, and 50%. Aortic root elastic modulus in the 4 Marfan models was doubled. Under diastolic pressure, regional stresses and strains were evaluated, and the percentage of leaflet coaptation was calculated. RESULTS: Root dilatation and stiffening significantly increased regional leaflet stress and strain compared with normal levels. Stress increases ranged from 80% to 360% and strain increases ranged from 60% to 200% in the 50% dilated Marfan model. Leaflet stresses and strains were disproportionately high at the attachment edge and coaptation area. Leaflet coaptation was decreased by approximately 20% in the 50% root dilatation model. CONCLUSIONS: Increasing root dilatation and root elastic modulus to simulate Marfan syndrome significantly increases leaflet stress and strain and reduces coaptation in an otherwise normal aortic valve. These alterations may influence the decision to use valve-sparing aortic root replacement procedures in patients with Marfan syndrome.     

Surgical correction of giant extracardiac unruptured aneurysm of the right coronary sinus of Valsalva: case report and review of the literature

We report a quite rare case of giant extracardiac unruptured aneurysm of the right coronary sinus of Valsalva with no clinical findings of Marfan syndrome or Ehlers–Danlos syndrome. A 52-year-old Chinese male was diagnosed having an aneurysm of the right sinus of Valsalva and moderate aortic regurgitation, while Bentall operation was performed successfully. The patient was discharged with no complications. Pathological examination revealed conspicuously medial mucoid degeneration of the aneurismal wall and absence of medial elastic fibers. Immediate results and early follow-up were uneventful.     

Repair of cartilage defects with periosteal grafts.

Alternative sources for repair of cartilage defects are limited and donor sites are associated with morbidity. It is known that cartilage development from periosteal grafts is possible. Various factors have been found positively to affect this process in experimental settings. However, all of these studies were limited to joint cartilage. We conducted an experimental study in rabbits for the investigation of the elastic cartilage regeneration from perichondrial and periosteal grafts together with the effects of hyaluronan on this process. 1 x 1 cm(2) cartilage defects were created on the elastic ear cartilage of rabbits. Four experimental groups with 18 ears in each group were created: Group 1 (repair with perichondrium graft), group 2 (repair with periosteum graft), group 3 (repair with periosteum graft+hyaluronan), group 4 (defect-only control group). Macroscopic and microscopic evaluations were done on the 4th, 8th and 12th weeks. Cellular morphology of the regenerated cartilage and its integration and similarity with adjacent cartilage were evaluated. Cartilage regeneration groups 1, 2 and 3 were found to be statistically different from the control group. There was not a significant difference between groups 1 and 2 or 2 and 3. There is no significant difference between perichondrial and periosteal grafts in cartilage regeneration, and hyaluronan has no beneficial effect on this process.     

Bentall Operation for a Child with Marfan Syndrome: A Case Report

A bstract Children with Marfan syndrome rarely undergo surgery for annuloaortic ectasia and aortic regurgitation in the first decade. A 7-year-old girl presented with congestive heart failure due to severe aortic regurgitation associated with annuloaortic ectasia (6 cm). She also had funnel chest. She underwent a Bentall operation and sternal turn-over with a satisfactory result. Since the aortic valve cusps had rolled edges, the aortic valve was not spared. Histology of the aortic valve cusps showed myxoid degeneration and fragmentation of elastic fibers.     

Renovascular hypertension in Marfan syndrome

A defect in fibrillin integrity predisposes patients with Marfan syndrome to vascular wall abnormalities, most notably aortic rupture and dissection. Renal vascular anomalies have not been described previously in children with Marfan syndrome. In this report, we detail data from a hypertensive 14-year-old girl with clinical stigmata of Marfan syndrome and a diagnostic evaluation significant for characteristic aortic root dilatation and aneurysm, as well as a disparity in renal size and function exacerbated by captopril administration. Renal arteriography confirmed a left main renal artery stenosis that was not amenable to balloon angioplasty. Surgical resection resulted in significant improvement in hypertension. Pathological examination of the resected renal artery segment revealed intimal proliferation, fragmentation of the elastic media, and inner medial dissection. This patient demonstrates that, in addition to the aorta, renal arteries can be affected with the characteristic vascular wall pathology of Marfan syndrome, resulting in systemic hypertension. These data suggest that children with Marfan syndrome and hypertension need to be evaluated carefully for the presence of renal anomalies. Received October 15, 1996; received in revised form and accepted January 10, 1997     

Innervation of the patella: An immunohistochemical study in mice

In the mouse, arthritis was induced by a single sub-patellar intraarticular injection of bacterial collage-nase. This procedure induces also patellar malalignment. A rich innervation of thin varicose calcitonin gene-related peptide (CGRP) and substance P (SP) immunoreactive fibers was found in the joint capsule, in the periosteum of the patella, in the synovial tissues at the lateral border of the patella, in the femoral groove, and in the subchondral bone of the patella and femur. Moreover, fibers were found in plica tissues between the quadriceps and patellar tendon, and the femoral groove.

After the collagenase treatment, the general innervation pattern was comparable to that of the controls, but CGRP and SP innervation was no longer detectable with the antibodies in the plica tissues, and was to a lesser extent detectable in the fat pad of the patella, in the lateral borders of the patella and in the proliferated synovial tissues. Signs of degenerated axonal profiles were observed in these locations with a polyclonal antibody to the growth-associated protein GAP-43/B-50. At all the other peripheral locations, such as the muscles, the GAP-43/B-50 distribution was normal.     

Retinoic acid responsiveness of cells and tissues in developing fetal limbs evaluated in a RAREhsplacZ transgenic mouse model

Limb morphogenesis is a complex phenomenon in which retinoids play an important role. Abnormal maternal retinoid levels from high oral doses cause fetal malformations, including abnormalities of the musculoskeletal system. Our purpose was to identify the retinoid-responsive cells in bone and cartilage during limb development by using a transgenic line of mice containing a reporter gene insert consisting of a retinoic acid response element linked to an Escherichia coli β-galactosidase gene. Transgenic fetuses from day 11.5 after conception to birth (day 20) were analyzed histologically. Retinoid-responsive cells and tissues were first seen in the limb bud at 12.5 days in the webs between the forming digits. The webs stained maximally at 14.5 days, after which staining intensity subsided. Staining in the muscles was detectable at 13.5 days, at a stage coinciding with myoblast fusion. Specific regions of perichondrium and periosteum also stained at this Stage. Occasional staining was observed in individual chondroblasts in all chondrogenic regions, including hypertrophic chondroblasts and certain articular surfaces of developing joints. Staining of these tissues decreased in intensity in subsequent stages. Osteoclasts started to express β-galactosidase at 15.5 days and continued to stain into maturity. Our results indicate that specific subsets of cells respond to retinoids at specific stages in the course of normal limb development. In hypertrophic chondrocytes and cells in the webs and joints that display such a response, retinoid-induced effects may be linked to cell death that occurs in these regions. Staining in muscle, perichondrium, and periosteum may reflect retinoid-induced effects associated with cell differentiation and growth. These results suggest that retinoids play a role in a variety of tissues, including bone and cartilage, at specific stages during morphogenesis.     

Human elastic cartilage engineering from cartilage progenitor cells using rotating wall vessel bioreactor

Transplantation of bioengineered elastic cartilage is considered to be a promising approach for patients with craniofacial defects. We have previously shown that human ear perichondrium harbors a population of cartilage progenitor cells (CPCs). The aim of this study was to examine the use of a rotating wall vessel (RWV) bioreactor for CPCs to engineer 3-D elastic cartilage in vitro. Human CPCs isolated from ear perichondrium were expanded and differentiated into chondrocytes under 2-D culture conditions. Fully differentiated CPCs were seeded into recently developed pC-HAp/ChS (porous material consisted of collagen, hydroxyapatite, and chondroitinsulfate) scaffolds and 3-D cultivated utilizing a RWV bioreactor. 3-D engineered constructs appeared shiny with a yellowish, cartilage-like morphology. The shape of the molded scaffold was maintained after RWV cultivation. Hematoxylin and eosin staining showed engraftment of CPCs inside pC-HAp/ChS. Alcian blue and Elastica Van Gieson staining showed of proteoglycan and elastic fibers, which are unique extracellular matrices of elastic cartilage. Thus, human CPCs formed elastic cartilage-like tissue after 3-D cultivation in a RWV bioreactor. These techniques may assist future efforts to reconstruct complicate structures composed of elastic cartilage in vitro.     

Organization and cellular biology of the perichondrial ossification groove of ranvier: a morphological study in rabbits.

The perichondrial ossification groove of Ranvier, a circumferential groove in the periphery of the epiphyseal cartilage, was studied in rabbits whose ages ranged from one week to eight months using light and electron microscopy, autoradiography after labeling with 3H-thymidine, 3H-proline, and 3H-glucosamine, and histochemical staining for proteoglycans and alkaline phosphatase. By these methods, three groups of cells were identified within the groove: 1. A group of densely packed cells deep in the groove, which are the progenitor cells for the osteoblasts that form the bone bark, a cuff of bone surrounding the epiphyseal growth-plate region and the adjacent part of the metaphysis. 2. A group of more widely dispersed, relatively undifferentiated mesenchymal cells and fibroblasts, some of which are chondroblast precursors that probably contribute to appositional chondrogenesis and growth in width of the epiphyseal cartilage. 3. Fibroblasts and fibrocytes among sheets of highly oriented and organized collagen fibers which form a fibrous layer that is continuous with the outer fibrous layer of the periosteum and with the perichondrium. This layer also sends fibers into the epiphyseal cartilage and anchors the periosteum firmly to the epiphyses as bone growth proceeds.     

Marfan syndrome and fibrillin disorders

Marfan syndrome is the second most common inherited connective tissue disorder after osteogenesis imperfecta. Musculoskeletal abnormalities are at the forefront of the clinical picture and count among the major diagnostic criteria for Marfan syndrome, together with cardiovascular and ocular system involvement. Early diagnosis is of the utmost importance since preventive measures significantly increase life expectancy and prevent the occurrence of impairments and disabilities. Marfan syndrome is due to mutations within the fibrillin-1 gene, which is the main protein of the microfibril network. Microfibrils play a crucial role in the trophicity and function of elastic tissue. Multidisciplinary management of the patients and their families is vital.     

Distribution of elastic fiber types in the epiphyseal region

Three types of elastic fibers have been described: mature elastic fibers, elaunin fibers, and oxytalan fibers. To our knowledge, their location in the immature epiphysis has never been previously reported. The aim of the present study was to use histochemistry, immunohistochemistry, and electron microscopy to demonstrate the distribution of each type of elastic fiber in the epiphyseal region of growing humans and rabbits. Histological samples were collected from the knees of 10 immature New Zealand White rabbits and four children of various ages. The Weigert resorcin-fuchsin, Gomori aldehyde-fuchsin, Verhoeff iron haematoxylin, and Fullmer-Lillie methods were used for histochemistry; anti-elastin monoclonal antibodies, for immunohistochemistry; and tannic acid, uranyl acetate, and lead citrate stain, for transmission electron microscopy analysis. Elastic fibers were detected in the perichondrium, the epiphyseal vessels, and the outer and middle zones of Ranvier's groove. Their orientation was longitudinal in the outer zone and circumferential in the middle zone of the groove. Oxytalan fibrils (i.e., bundles of filaments of 10–12 nm in diameter that do not contain elastin) and elaunin fibers (i.e., filaments that cross discontinuous aggregates of elastin) were more plentiful in the middle zone and decreased with age, whereas mature fibers were more numerous in the outer zone and increased with age. This organization of elastic fibers seems to indicate an age-related process of maturation of the elastic network. The contribution of these fibers to the mechanical properties of the epiphyseal plate and to the growth process remains to be determined.     

Osteochondrogenesis of Free Periosteal Grafts in the Rabbit Iliac Crest

The influence of the bone marrow, cortical bone and apophyseal cartilage of the iliac crest on osteochondrogenesis from free autogenous periosteal grafts was studied histologically in 8-week-old rabbits. Tibial periosteum was transplanted around the iliac crest, from which the periosteum had been removed from the inner side, periosteum and cortical bone in an area on the outer side and perichondrium from the apophyseal cartilage. Most bone formation occurred in the area with periosteum in contact with the bone marrow of the cancellous bone. By means of an isolating Nucleopore filter^®, it was revealed that the most vigorous of this bone formation originated from the periosteal graft. Further, it was noted that in the series with the Nucleopore filter, bone formation was slower than in the series without the filter, suggesting some inductive factors. No bone formation occurred in the apophyseal area.     

Aneurysm of the internal carotid artery and cervical mega-dolicho-arteries in Marfan syndrome

The authors describe the case of a Marfan syndrome who presented a giant intracranial internal carotid aneurysm associated with elongation and tortuosity of internal carotid and vertebral arteries on both sides. The skin microscopic examination showed fragmentation and distorsion of elastic fibers. There was no microscopic study of the vessels. Extra and intracranial vascular abnormalities are rarely reported in marfan syndrome: cardiovascular changes are seen mostly in aorta and pulmonary artery. In the literature are reported some giant aneurysms, dissections and dilatations of carotid, basilar and vertebral arteries. Usually the microscopic examination of the vessels show cystic medial necrosis. Other connective tissue diseases (pseudo-xanthoma elasticum, Ehlers-Danlos syndrome, progeria) are described with such clinical abnormalities. Reference is made to the possibility of unknown histological and chemical lesions weakening the vessels in patients without connective tissue disorders and presenting with arterial dissection or arterial aneurysm. So vessels would be more sensible to aging, arteriosclerosis or hypertension.     

Endovascular treatment of ruptured axillary and large internal mammary artery aneurysms in a patient with Marfan syndrome

Marfan syndrome is an autosomally inherited disorder affecting the synthesis of connective tissues. Vascular manifestations of Marfan syndrome include aneurysmal dilatation of the aortic root, aortic dissection, and rupture. Peripheral aneurysms are mostly reported in the iliac, femoral, and subclavian arteries. We report a Marfan patient with a ruptured axillary artery aneurysm and a large left internal mammary artery aneurysm. The axillary aneurysm was successfully excluded using covered stent grafts, and the left internal mammary artery aneurysm was effectively coiled. Duplex ultrasound imaging at 4 months and computed tomography at 9 months demonstrated complete thrombosis and exclusion of both aneurysms with patent subclavian-axillary stent grafts.