Lamellar bone formation in an atherosclerotic plaque of the carotid artery, with a review of histogenesis--a case report

Histopathology of periarticular non-hereditary heterotopic ossification

In the mature adult skeleton, new bone formation is normally restricted to regeneration of osseous tissue at sites of fracture. However, heterotopic ossification, or the formation of bone outside the normal skeleton, can occur within muscle, adipose, or fibrous connective tissue. Periarticular non-hereditary heterotopic ossification (NHHO) may occur after musculoskeletal trauma, following CNS injury, with certain arthropathies, or following injury or surgery that is often sustained in the context of age-related pathology. The histological mechanism of bone development in these forms of heterotopic ossification has thus far been uncharacterized. We performed a histological analysis of 90 bone specimens from 18 patients with NHHO secondary to defined precipitating conditions, including traumatic brain injury, spinal cord injury, cerebrovascular accident, trauma without neurologic injury, and total hip or knee arthroplasty. All bone specimens revealed normal endochondral osteogenesis at heterotopic sites. We defined the order of sequence progression in NHHO lesion formation as occurring through six distinct histological stages: (1) perivascular lymphocytic infiltration, (2) lymphocytic migration into soft tissue, (3) reactive fibroproliferation, (4) neovascularity, (5) cartilage formation, and (6) endochondral bone formation. This study provides the first systematic evaluation of the predominant histopathological findings associated with multiple forms of NHHO and shows that they share a common mechanism of lesion formation.

Evidence for active regulation of pro-osteogenic signaling in advanced aortic valve disease

OBJECTIVE

To test the hypothesis that valvular calcium deposition, pro-osteogenic signaling, and function can be altered in mice with advanced aortic valve disease.

METHODS AND RESULTS

"Reversa" mice were given a Western-type diet for 12 months and screened for the presence of aortic valve stenosis. Mice with advanced valve disease were assigned to 1 of 2 groups: (1) those with continued progression for 2 months and (2) those with regression for 2 months, in which lipid lowering was accomplished by a genetic switch. Control mice were normocholesterolemic for 14 months. Mice with advanced valve disease had massive valvular calcification that was associated with increases in bone morphogenetic protein signaling, Wnt/β-catenin signaling, and markers of osteoblastlike cell differentiation. Remarkably, reducing plasma lipids with a genetic switch dramatically reduced markers of pro-osteogenic signaling and significantly reduced valvular calcium deposition. Nevertheless, despite a marked reduction in valvular calcium deposition, valve function remained markedly impaired. Phosphorylated Smad2 levels and myofibroblast activation (indexes of profibrotic signaling) remained elevated.

CONCLUSIONS

Molecular processes that contribute to valvular calcification and osteogenesis remain remarkably labile during the end stages of aortic valve stenosis. Although reductions in valvular calcium deposition were not sufficient to improve valvular function in the animals studied, these findings demonstrate that aortic valve calcification is a remarkably dynamic process that can be modified therapeutically, even in the presence of advanced aortic valve disease.

Heterotopic ossification: Review of histologic findings and tissue distribution in a 10-year experience

Heterotopic ossification (HO) within tissues involved by a pathologic process is a well-recognized phenomenon. It is most frequently observed in atherosclerotic plaques, in soft tissue around joints, and in the central nervous system. Less frequently, carcinomas and some benign neoplasms will undergo heterotopic ossification. We performed a retrospective review of our experience with HO over a 10-year period to determine the frequency and tissue site distribution of heterotopic ossification. A computerized review of surgical pathology records of approximately 126,000 reports revealed 85 cases in which heterotopic ossification, ectopic bone or metaplastic bone was specifically mentioned in the surgical pathology diagnosis. Twenty-two cases were neoplasms of non-osseous tissues, and 63 cases were non-neoplastic lesions. Immunohistochemical staining for bone morphogenic proteins (BMP) 1, 4, and 6 was performed. Fourteen cases showed staining for BMP-1, 22 cases showed staining for BMP-4, and five cases showed weak staining for BMP-6. HO is a relatively infrequent finding and is more commonly seen in degenerative and reparative conditions than in neoplasms.

Free-floating thrombus of the carotid artery: Literature review and case reports

BACKGROUND

Free-floating thrombus (FFT) of the carotid artery is an uncommon entity that usually presents as an acute emergency. Management is based on case reports and series because the natural history and optimal treatment are unknown. This study was conducted to systematically review the world literature in an attempt to better understand FFT, its presentation, distribution, management, and outcome.

METHOD

A literature search in all languages was performed of the PubMed database (> or =1950s) and Medline database (1966-November 2004). All relevant articles were reviewed and their references analyzed in a similar manner for further literature. Cases from the authors' institutions were reviewed as well. All cases within the reports were individually assessed for inclusion or exclusion. Inclusion required that the FFT originate or anchor within the carotid artery (ie, excluding emboli, arch thrombi with extensions into the carotid artery), be partially occluding (ie, excluding occlusions, "string-sign," microscopic thrombus), and ideally have an elongated or protrusive morphology, circumferential flow around the distal portion, and cyclical motion with the cardiac cycles.

RESULTS

There were 61 reports reviewed, of which 43 contained FFT cases. These reports had 342 cases (including the current series) that were reviewed, of which 145 met our inclusion criteria. A database was created for qualitative and quantitative assessment of all cases. When data were pooled, appropriate statistical analysis was performed. A limitation of the study is that FFT is under-reported and ill defined, which limited the analysis in quantity and quality. In addition, reporting is not uniform, and therefore, significant data were not always present. In attempting to define FFT and include or exclude cases, subjectivity is inherent.

CONCLUSIONS

FFT is more frequently reported in men than women, with a ratio of nearly 2:1 (P < .0001), and at a younger age than in most patients with carotid disease (P < .0001 when compared with North American Symptomatic Carotid Endarterectomy Trial, European Carotid Surgery Trial, and Asymptomatic Carotid Surgery Trial). Symptoms are present in 92% of patients. There was a trend for patients with FFT to be hypercoagulable (47% of those serologically tested). The internal carotid artery was the most commonly affected (75%), with atherosclerosis being the most common associated pathology. Medical and surgical management have both been used, with neither clearly superior to the other. Medical management for stabilizing neurologic deficits has less risk and less benefit than surgical intervention.

Umbilical Cord Stromal Cells (UCSC)

The identification of appropriate cell types is necessary to establish cell-based therapies in regenerative medicine. These cell types must (1) be available in an appropriate amount, (2) be easy to obtain, (3) be sufficiently expandable in vitro, and (4) fit to or at least be able to differentiate into the required cell type. Since the umbilical cord is available without any intervention and represents a notable amount of tissue, we consider it to be a promising source for isolating cells for cell-based therapies. This study demonstrates that umbilical cord stromal cells (UCSC), the connective tissue cells of the umbilical cord, can be isolated in sufficient quantities and be well expanded. UCSC feature phenotypic plasticity and thus are functionally similar to stem cells. UCSC can be differentiated into cells with osteoblastic properties (expression of alkaline phosphatase, formation of bone nodules). It is concluded that the umbilical cord should no longer be regarded as valueless tissue and be unthinkingly discarded. Instead, it should be considered a valuable resource for the isolation of potent cells for cell-based therapies, especially for treatment of bone defects.

Fracture and the risk of coronary events in women with heart disease

BACKGROUND

Osteoporosis is associated with aortic calcification and cardiovascular mortality. However, whether skeletal fractures predict the risk of coronary events is unknown.

METHODS

We used Cox proportional hazards models to determine whether postmenopausal fracture was associated with the risk of coronary heart disease events among the 2763 postmenopausal women with known coronary disease enrolled in the Heart and Estrogen/progestin Replacement Study. Because fractures occurred before enrollment (in 615 women) and during follow-up (in 276 women), we treated incident fracture as a time-dependent covariate in our models.

RESULTS

During a mean follow-up of 4.1 years, 361 women had coronary heart disease events. The risk of these events was 25% lower in women who sustained fractures than in those without fractures (hazard ratio [HR] = 0.74; 95% confidence interval [CI]: 0.57 to 0.96; P = 0.02). This association was not confounded by physical activity or by factors associated with both fracture and coronary heart disease events (HR = 0.75; 95% CI: 0.57 to 0.98; P = 0.04).

CONCLUSION

Postmenopausal women with heart disease who had skeletal fractures had a reduced risk of subsequent coronary events. This unexpected association, if confirmed in future studies, could influence risk-related treatment strategies for cardiovascular disease.

In vitro investigation of calcium distribution and tissue thickness in the human thoracic aorta

Atherosclerosis represents a significant cause of morbidity and mortality in the western world. Manifestations of atherosclerotic disease among the elderly include the development of raised lesions that often include calcified regions with material properties similar to bone. There is little information available about the amount and distribution of these calcified plaques within the human aorta, partly due to the difficulty in obtaining this information during in vivo studies. We report the results of a cadaveric investigation of thoracic aortic wall thickness, diameter and calcium content. A non-destructive x-ray imaging technique was used to obtain two-dimensional maps of total thickness and mineral content in excised thoracic aortic specimens. In a study of 39 individuals (23 male and 16 female, aged 20-92 years) we report a significant non-linear correlation between calcium burden and age, with calcium deposition most commonly occurring proximal to the ostia of major branching vessels. We also found a significant linear correlation between age and both total aortic wall thickness and aortic diameter. An improved understanding of the pathological changes in the ageing thoracic aorta may be useful in the development of strategies to reduce the undesirable vessel calcification associated with atherosclerosis.