Ultrastructural evidence for collagen degradation in the walls of varicose veins

Morphological restructuring of smooth muscles elements of the wallgreat saphenous vein of a person on the lower leg during the development of varicose transformation

Introduction. Further study of the structural restructuring of the wall of the great saphenous vein throughout a person’s life with the development of chronic venous diseases is an urgent task of phlebology.

The purpose of the study. Research of the morphological restructuring of smooth muscleselements of the human great saphenous vein wall on the calf in norm, ectasia and development of varicose transformation.

Materials and methods. The study of morphological restructuring of the great saphenous vein wall on the calf was carried out in 3 comparison groups by light microscopy. In 1th group, the structure of the GSV wall was studied on autopsy material of people who died from various causes at the age of 5 to 80 years. In the 2nd and 3rd groups, fragments of GSV in the calf were taken by biopsy during the execution of the operations for varicose veins. All patients underwent ultrasound mapping before surgery to determine the presence and degree of ectasia, varicose transformation and retrograde blood flow. For histological analysis in the groups, 140 GSV fragments were removed in 1-group, 165 BPV fragments in 2-group, and 250 GSV fragments in 3-group.

Results. The general morphological analysis of histological preparations made it possible to visually identify various variants of changes in smooth muscleselements inherent in the inner, middle and outer shells of the GSV wall. The selected variants of reconstruction of the smooth muscleselements were combined into 10 morphological types.

Conclusion. Age-related morphological changes in the smooth muscleselements in the GSV wall on the calf, over the course of a person’s life, do not have the same character as changes occurring in its wall during the development of its ectasia and varicose transformation.

Pathophysiology of venous ulceration

Our understanding of the pathophysiologic process of venous ulceration has dramatically increased during the past two decades because of dedicated, venous-specific basic science research. Currently, the mechanisms regulating venous ulceration are a combination of macroscopic and microscopic pathologic processes. Macroscopic alterations refer to pathologic processes related to varicose vein formation, vein wall architecture, and cellular abnormalities that impair venous function. These processes are primarily caused by genetic factors that lead to the destruction of normal vein wall architecture and venous hypertension. Venous hypertension causes a chronic inflammatory response that over time can cause venous ulceration. The inciting inflammatory injury is chronic extravasation of macromolecules and red blood cell degradation products and iron overload. Chronic inflammation causes white blood cell extravasation into the dermis with secretion of numerous proinflammatory cytokines. These cytokines transform the phenotype of fibroblasts to a contractile phenotype that increases tension in the dermis. In addition, iron overload keeps macrophages in an M1 phenotype, which leads to tissue destruction instead of dermal repair. Current surgical and medical therapies are primarily directed at eliminating venous hypertension and promoting venous ulcer wound healing. Despite advances in our understanding of venous ulcer formation and healing, ulcers still take an average of 6 months to heal, and ulcer recurrence rates at 5 years are >58%. To improve the care of patients with venous ulcers, we need to further our understanding of the underlying pathologic events that lead to ulcer formation, prevent healing, and decrease ulcer-free recurrence intervals.

The Histopathology of Varicose Vein Disease

Varicosity is a complex venous pathology affecting the lower extremities. The exact etiology and physiopathology of varicose vein disease remain, however, unclear. Several theories exist from incompetence of the valves to a disturbance of the smooth muscle cells (SMC) and extra-cellular matrix (ECM) organization providing a weakness of the venous wall. Multiple studies have been performed to explain the underlying mechanisms of varicosity inducing alterations in the expression patterns of the endothelium, SMC, and ECM. In that respect, most attention has been focused on the alteration of the endothelium due to blood stasis and hypoxia inducing migration/proliferation of the medial SMC into the intima. Also, studies in the deformation of the ECM induced by alterations of the expression patterns of the metalloproteinases (MMP) and their inhibitors (TIMPs) have been put forward to explain the etiology of varicosity. However, less attention has been paid to the hormonal changes that occur during pregnancy and menopause, crucial factors to be involved in the etiology of varicosity. Since alteration of the estrogen receptor-b (ERb) expression could enhance directly the cellular volume of SMC and thus the disorganization of the contractile-elastic units, hypertrophy of SMC must be accounted a pivotal role that could induce the weakness of the venous wall. Altogether, this review summarizes an overview of the latest findings of varicosity with respect to the histopathological changes of the different cellular components of the varicose vein wall related to functional and morphologic alterations.

Histopathological Studies of the Valves of Varicose Veins

In order to elucidate the cause and pathology of varicose veins in the lower limb, the terminal valves of the long saphenous vein in 36 patients with varicose veins and ten control cases have been examined by light and transmission electron microscopy. Valve failure in the varicose group was thought to start with a depression in the valvular commissure and to proceed to extension of this depression and expansion of the space between the two valves. It was further thought that, in this group, reversal and tortuosity of the valve cusps, hyperplasia of the collagen fibres and irregularity of the course of elastic fibre layers represented secondary changes.

In almost all cases, intimal fibrous thickening was present in the vein wall, and this was histologically similar to so-called phlebosclerosis. It was further confirmed that the degree of intimal thickening was correlated to the disease period, with greater thickening noted at the region under greater pressure load. Phlebosclerosis seemed to be proportional to the size of stress and pressure load time.

Changes in Metalloproteinase (MMP-1, MMP-2) Expression in the Proximal Region of the Varicose Saphenous Vein Wall in Young Subjects

Objective:

An evaluation of the proteoglycan perlecan, collagen I and III, and metalloproteinases MMP−1, −2, −3 and −9 was performed to explore the possible relationships between ageing, affected vein region and reactive state of the varicose vein wall.

Methods:

Segments of saphenous vein were obtained from healthy subjects and from those with varicose veins. The vein specimens were subdivided according to subject age (<50/^50) and vein source (distal/proximal).

Results:

The walls of control vein specimens acquired a more collagenous appearance with age. These changes were not accompanied by significant modifications in the immunohistochemical markers used. In specimens from young patients, proximal varicose vein segments showed an increase in MMP-1, MMP-2 and MMP-9 expression. Subjects of more advanced age showed an increase in perlecan expression.

Conclusion:

This increase in MMPs could lead to the acceleration of the final fibrosclerotic process characteristic of the varicose vein wall.

Associations of NF-kappaB and bax with apoptosis in varicose veins of women of different age groups

The study aimed at detecting apoptotic endothelial cells (ECs) and smooth muscle cells (SMCs) together with determining expression of NF-kappaB (p105/p50) and Bax in varicose vein walls. Women (n = 35) undergoing the excision of varicose veins were divided into 3 groups: younger than 35 years (I), 36–50 years (II), and older than 50 years (III). Apoptosis was determined by the TUNEL method, NF-kappaB and Bax expression by immunohistochemistry. The percentage of apoptotic ECs and SMCs in the layers of varicose vein wall increased in groups II and III. NF-kappaB expression had the lowest level in Group II with particularly low level in the media. Contrariwise, Bax expression levels in Group II were increased. The study revealed that in varicose veins ECs and SMCs apoptosis increased with advancing age. If increase in apoptosis during earlier stages of varicosities is probably regulated by intrinsic pathway, then in older patients other signaling pathways may be involved.

Pathogenesis of primary varicose veins

BACKGROUND

Valvular incompetence and reflux are common features of primary varicose veins, and have long been thought to be their cause. Recent evidence, however, suggests that changes in the vein wall may precede valvular dysfunction.

METHODS

A literature search was performed using PubMed and Ovid using the keywords 'varicose vein wall changes', 'pathogenesis', 'aetiology' and 'valvular dysfunction'. Articles discussing the pathophysiology of complications of varicose veins, such as ulceration, recurrence, thrombophlebitis and lipodermatosclerosis, were excluded.

RESULTS AND CONCLUSION

Positive family history, age, sex and pregnancy are important risk factors for varicose vein formation. Areas of intimal hyperplasia and smooth muscle cell proliferation are often noted in varicose veins, although regions of atrophy are also present. The total elastin content in varicose as opposed to non-varicose veins is reduced; changes in overall collagen content are uncertain. Matrix metalloproteinases (MMPs), including MMP-1, MMP-2, MMP-3, MMP-7 and MMP-9, and tissue inhibitor of metalloproteinase (TIMP) 1 and TIMP-3 are upregulated in varicose veins. Activation of the endothelium stimulates the recruitment of leucocytes and the release of growth factors, leading to smooth muscle cell proliferation and migration. Dysregulated apoptosis has also been demonstrated in varicose veins. An understanding of the pathophysiology of varicose veins is important in the identification of potential therapeutic targets and treatment strategies.

Association of primary varicose veins with dysregulated vein wall apoptosis

BACKGROUND

Disordered programmed cell death may play a role in the development of superficial venous incompetence. We have determined the number of cells in apoptosis, and the mediators regulating the intrinsic and extrinsic pathways in specimens of varicose vein.

METHODS

Venous segments were obtained from 46 patients undergoing surgical treatment for primary varicose veins. Controls samples were obtained from 20 patients undergoing distal arterial bypass grafting surgery. Segments of the distal and proximal saphenous trunk as well as tributaries were studied. Cell apoptoses and mediators of the mitochondrial and trans membrane pathway were evaluated with peroxidase in situ apoptosis detection, Bax and Fas detection, caspase-9 and 8 detection in the medial layer.

RESULTS

Disorganised histological architecture was observed in varicose veins. Primary varicose veins also contained fewer peroxidase in situ-positive cells than control veins (2.6% S.D. 0.2% versus 12% S.D. 0.93%, P=.0001, Mann-Whitney u test), fewer Bax positive cells (2.1.% S.D. 0.3% versus 13% S.D. 0.9%, P=.0001) and fewer Caspase 9 positive cells (3.2% S.D. 1% versus 12% S.D. 1.3%, P=.0001). Similar findings were observed in saphenous trunk, main tributaries and accessory veins. In patients with recurrent varicose veins in whom the saphenous trunk had been preserved showed similar findings to primary varicose veins. Residual varicose veins contained fewer peroxidase in situ-positive cells than healthy veins (3.2% S.D. 0.6% versus 11% S.D. 2%, P=.0001), fewer Bax positive cells (2.2% S.D. 0.3% versus 12% S.D. 0.7%, P=.0001) and fewer Caspase 9 positive cells (2.6% S.D. 0.6% versus 12% S.D. 1%, P=.0001). Immunohistochemical detection for Fas and caspase 8 remained equal was the same in the varicose vein and control groups.

CONCLUSION

Apoptosis is down regulated in the medial layer of varicose veins. This dysregulation is attributable to a disorder of the intrinsic pathway and involves the great saphenous vein trunk, major tributaries and accessory veins. This process may be among the causes of primary varicose veins.

A journey across the wall of varicose veins: what physicians do not often see with the naked eye

OBJECTIVE

To examine varicose veins (VVs) from inside out in order to help surgeons and general practitioners better understand the pathogenesis of the disease and improve their management.

MATERIAL AND METHODS

A comprehensive examination of the wall of VVs was performed using transmission electron microscopy. The ultrastructural morphology of the collagen, elastin and smooth muscle content of the wall was analyzed in a sample of 10 patients (4 male and 6 female) and 10 matched controls aged between 37 and 50 years.

RESULTS

Analysis of the tunica media revealed that the smooth muscle cells were significantly separated from each other by a marked increase in amorphous and fibrous tissue in which many of the collagen and elastin fibers lost their normal structural arrangement. The cells contained a large number of membrane-bound intracellular vesicles and cytoplasmic vacuoles. The collagen fibers were smaller and thinner than what is commonly seen in normal veins, and they were widely separated from each other. A light electron-lucent center was observed in the middle of the fibers. Similar changes were also seen in the intima and were associated with irregular plaque-like intimal thickening.

CONCLUSION

Our study revealed a significant separation among smooth muscle cells in the wall of VVs, and the presence of an abnormal amorphous extracellular matrix and intracytoplasmic vacuoles could reflect 'unusual' possible secretory and phagocytic roles of smooth muscle cells. This could provide an important explanation for the abnormal contractile function of these cells in VVs.

Dysregulated apoptosis in primary varicose veins

OBJECTIVE

Programmed cell death plays a critical role in various physiological processes. To investigate its possible pathogenic role in primary varicose veins we studied histological changes in surgical specimens from human varicose veins. In varicose and healthy veins, we also determined the number of cells in apoptosis, and investigated mediators regulating the intrinsic apoptotic mitochondrial pathway (Bax and caspase 9).

METHODS

A total 23 varicose veins were obtained from 18 patients undergoing lower-extremity varicose vein surgery for primary varicose disorders. We used nine healthy veins obtained from nine patients undergoing distal arterial bypass grafting surgery as controls. The venous segment analysed was the distal part of the greater saphenous vein. Specimens for histological examination were stained with hematoxylin and eosin, trichromic and Victoria blue. Cell apoptoses and mediators of the mitochondrial pathway were detected in the media by immunohistochemistry using antibodies to peroxidase in situ apoptosis, Bax and caspase 9. Results were expressed as indexes for the three antibodies tested. The Mann-Whitney test was used to compare the results obtained in the two groups.

RESULTS

Varicose vein specimens exhibited a more disorganised architecture than healthy veins and showed an increased number of collagen fibres and a decrease in the density and size of elastic fibres. All anti-apoptotic antibodies tested detected significantly fewer immunoreactive cells in tissue sections from the media of varicose veins than of healthy veins (peroxidase in situ, varicose veins (VV) median 2.4% (inter-quartile range 1.6-3.9) versus control (C) 14% (IQR 8.8-19); Bax, VV 1.4% (IQR 0.36-2.4) versus C 11% (IQR 7.6-15); and caspase 9, VV 1.7% (IQR 0.06-3.4) versus C 10% (IQR 9.1-12), P=0.0001 (Mann-Whitney test).

CONCLUSION

Apoptosis is down regulated in the medial layer of varicose veins. This dysregulation of the cellular mechanism that maintains normal tissue integrity is mediated through the intrinsic apoptotic pathway and may be among the causes of primary varicose veins.

Smooth Muscle Cell Apoptosis in Primary Varicose Veins

OBJECTIVES

One of the important factors responsible for vessel wall remodelling is programmed cell death. In the paper the role of smooth muscle cell (SMC) apoptosis in primary varicose veins (PVV) is investigated.

MATERIAL AND METHODS

Vein specimens were obtained from 40 patients with PVV. In each case proximal and distal (upper crural) great saphenous veins (GSV) were harvested. Morphometric computer assessed quantitative evaluation of SMCs, collagen and elastin content was carried out. Apoptotic cells were detected by TUNEL assay. The levels of p53, BAX, BCLl-2 and p21 mRNA expression were assessed by real time RT-QPCR and the presence of respective proteins in the vessel wall was confirmed by immunohistochemistry.

RESULTS

In the proximal GSV segments a significant increase of p53, p21 and BCL-2 mRNA levels was found in PVV patients. In the distal segments BAX and BCL-2 expression levels were higher. Taking into account the patient age, elevated p53 mRNA expression level was noticed in the distal incompetent GSVs of young PVV patients. In this group a statistically significant increase in the apoptotic index (APIx) within the vein media was found which correlated positively with p53 mRNA expression level. There was no increase of the apoptotic activity in elderly patients that led to the structural changes increase. In proximal GSV segments, despite SMC amount reduction or presence of structural changes in perivalvular wall region, no increase of the APIx with was noticed.

CONCLUSIONS

P53-related apoptosis is one of the regulatory mechanisms of vein wall homeostasis maintenance. During varicose vein development its activation is related to the early stages of the disease. In the further course, the down-regulation of the SMC apoptosis within the vein media leads to the structural changes increase. The reduction of the SMC population corresponding to an increase of p21 expression in proximal saphenous vein segments suggests that the cell cycle disturbances may lead to the 'weakness' of the proximal GSV wall. Valve injury is not the only factor leading to the varicose veins occurrence.

Gross anatomy of primary varicose veins observed in endoscopic surgery

The gross anatomy of varicose veins is one of the most important factors in the study of varicosity. Because of wide variations in the extent of involvement and degree of severity of varicose veins, it is difficult to obtain live and intact specimens of varicose veins. With good illumination and magnified monitor viewing, the varicositic main channel, its tributaries, and the incompetent perforating veins can be dissected and visualized clearly during endoscopic surgery. Thus, the whole range of varicosities can be observed directly in situ. Characteristic features of the varicosities of 350 limbs have been recorded by video and photographs for study and classification. These features include: 1) poor contractility of varicose veins; 2) dilated and tortuous changes of varicose veins; 3) saccular or lateral bulging deformities of vein walls, or both; 4) uniformly dilated and tortuous deformities of a long vein; 5) varicositic changes of the accessory vein; 6) anatomic abnormalities of varicose veins, such as supernumerary tributaries, varicositic clusters, and a crowded relationship among the long saphenous vein, perforating vein and tributaries; 7) various conditions of the perforating veins; and 8) the close relationship among the long saphenous vein, perforating veins, and the saphenous nerve. These data provide valuable information for the study and management of primary varicose veins.

Smooth muscle changes in the cephalic vein of renal failure patients before use as an arteriovenous fistula (AVF)

Complications in arteriovenous fistula (AVF) occur in up to 35% of renal failure patients on hemodialysis. The most frequent complication is thrombosis, usually from stenotic lesions in the venous outflow system. To study the pre-existing smooth muscle changes in the cephalic vein of these patients, we prospectively collected a total of 17 cephalic vein specimens from 3 normal controls and 14 renal failure patients undergoing primary AVF construction on the chosen limb. After preparation, ultrathin sections were stained with uranyl and lead acetate and were examined under the transmission electron microscope (TEM). Compared with the normal controls, abnormal fibrous infiltration of the intima and the media and varying degrees of smooth muscle degenerative changes were observed in all the cephalic vein sections of renal failure patients. Smooth muscle cells (SMCs) lost their normal fusiform shape and were widely separated by increased amount of irregularly disposed, extracellular collagen fibers. Other cellular abnormalities included irregular cell membrane, granular cytoplasm, Peri- and Paranuclear vacuoles and mega mitochondria. SMCs also showed morphological expression of phagocytosis of collagen and elastic fibers as a sign of remodeling of the vein wall. In conclusion, pre-existing wall and smooth muscle changes were observed in all the cephalic vein sections of renal failure patients, which may contribute to the later complications of AVFs.

Intimal changes in varicose veins: an ultrastructural study

In order to study the structural changes in the intimal layer of varicose veins, we prospectively collected a total of 23 vein specimens from both the normal proximal thigh long saphenous (LSV) in 3 young trauma patients and from the unstripped proximal LSV near the sapheno-femoral junction and the distal calf blowouts in 10 primary varicose veins patients. Paraffin sections stained with hematoxylin and eosin were examined under the light microscope while ultra-thin sections were examined under the transmission electron microscope (TEM). Compared with the normal control LSV, varicose vein sections showed increase in the diameter of the lumen, hypertrophy of the wall and elongation and invagination of the intima. Along these invaginations, endothelial cells were compressed, elongated and thinned out. The cells also showed progressive degeneration and were finally lost into the lumen, leaving only the basal lamina to form the luminal surface. This invited blood components like platelets and red blood cells to stick to the bare intima and to penetrate through the wall. This may form the basis of the clinical condition of superficial thrombophlebitis, which sometimes complicates cases of varicose veins. In conclusion, varicose veins showed increased diameter of the lumen and hypertrophy, elongation and invagination of the intima. There was marked degeneration of the endothelial cells and desquamation of the endothelial layer.

Smooth muscle changes in varicose veins: an ultrastructural study

In order to understand the pathology of varicose veins, we prospectively collected a total of 23 vein specimens both from the normal proximal thigh long saphenous vein (LSV) in 3 young trauma patients and from the unstripped proximal LSV near the sapheno-femoral junction and the distal calf blowouts in 10 primary varicose veins patients. Ultra-thin sections were examined under the transmission electron microscope (TEM). Compared with the normal control LSV, varicose vein sections showed increase in the diameter of the lumen, hypertrophy of the wall and elongation and invagination of the intima. Smooth muscle cells (SMCS) lost their normal fusiform shape and were widely separated by increased amounts of extra-cellular collagen fibers. The cells underwent marked degeneration, vacuolization and disintegration into fiber-like material and small separated fragments. SMCs were seen in the subintimal tissue and some of them were lost into tile lumen. SMCs also showed marked phagocytic activity, engulfing not only collagen and elastic fibers, but also other smooth muscle cells. Although these changes were more marked and advanced in the distal calf blowouts, they were also present in the proximal, clinically non-dilated LSV. In conclusion, SMCs of varicose veins show severe degeneration in both the distal calf blowouts and the proximal, clinically non-varicose LSV. It appears that they both form and phagocytose collagen and elastic fibers and play a major role in the pathogenesis of varicose veins.

Expression of molecular mediators of apoptosis and their role in the pathogenesis of lower-extremity varicose veins

PURPOSE

In an earlier study, we observed a significant decrease in apoptosis in varicose veins, as compared with healthy veins, indicating that deregulated apoptosis plays a role in the pathogenesis of varicosities. In addition, significant differences were noted in the expression and subcellular localization of the cell cycle regulatory protein, cyclin D1 in varix tissues, as compared with controls. Because cell cycle checkpoint controls are linked to the signaling and execution of apoptotic cascades, we examined the expression of bcl-2 family members bax and bcl-x, known molecular mediators of apoptosis, and that of poly (ADP-ribose) polymerase (PARP), a downstream substrate of DNA cleavage.

METHODS

Twenty varicose vein specimens were retrieved from 20 patients (10 men, 10 women; mean age, 53.6 +/- 4.7 years) undergoing lower-extremity varicose vein excision. Healthy greater saphenous vein segments (n = 27) were obtained from 27 patients (14 men, 13 women; mean age, 59.5 +/- 2.4 years) undergoing infrainguinal arterial bypass grafting surgery. All tissues were distal portions. As per CEAP classification for chronic lower-extremity venous disease, most of the patients were in class 2 for clinical signs (n = 11); some patients were in class 3 (n = 4) or class 4 (n = 4), and only one patient was in class 5. Five 5-microm thick sections from formalin-fixed, paraffin-embedded specimens were used as a means of immunohistochemically localizing the expression of bax, bcl-x, and PARP, and 10 random high-power fields per section were evaluated by two independent reviewers blinded to the clinical findings. Statistical analyses were conducted by means of chi(2), analysis of variance, Student and Fisher exact t tests with StatView software.

RESULTS

Immunoreactivity to pro-apoptotic bax was significantly higher in the normal veins (P <.001). Cytoplasmic expression of bcl-x was prominent in the cells of the vasa vasorum in both varicose and healthy veins. PARP expression was diminished in the varicose vein group, with 2.8 +/- 0.7 (P =.01) and 1.4 +/- 0.5 (P =.05) cells per high-power field in the intima and media, respectively. Neither bax nor PARP was noted in the adventitia of varicose veins, although their expression was detected in this layer of the control group (P <.001).

CONCLUSION

The entry of smooth muscle cells into the apoptotic pathway may be regulated by the induction of bax in this model, because there is significant presence of this pro-apoptotic protein in healthy veins. Both bax and PARP are downregulated in varicose veins, as compared with healthy veins, and this may play a significant role in the pathogenesis of varicose veins.

Smooth muscle cell modulation and cytokine overproduction in varicose veins. An in situ study

The exact aetiology and physiopathology of varicose disorders remain unclear. The aim of the present work was to study, in situ, the morphology and composition of cellular and matrix components in varicose veins compared with control veins and to identify factors that could contribute to varicose remodelling. A combined histological, immunohistochemical, and biochemical approach was used. Longitudinal sections of varicose (n=12) and control veins (n=9) were studied to assess the organization, structure, and phenotype of smooth muscle cells; the localization of microvascular endothelial cells; the distribution of connective tissue proteins; and the localization of cytokines. These cytokines were further quantified by ELISA. Considerable heterogeneity of the varicose vein wall was observed, with a succession of hypertrophic and atrophic segments, presenting severe disorganization of the medial layer and numerous areas of intimal thickening. In hypertrophic portions, medial smooth muscle cells showed marked alterations suggesting modulation from a contractile to a proliferative and synthetic phenotype; furthermore, the number of vasa vasorum was increased. In contrast, in atrophic portions, both cellular and matrix components were decreased. TGFbeta1 (p< or =0.005) and bFGF (p< or =0.001) were increased and VEGF was not significantly modified in varicose veins when the results were expressed per mg of DNA. These results show that phenotypic modulation of smooth muscle cells, altered extracellular matrix metabolism, and angiogenesis are the main mechanisms contributing to the morphological and functional modifications of varicose remodelling. The increased expression of bFGF and TGFbeta1 by varicose vein cells may play a pivotal role in the hypertrophy of the venous wall, but the exact mechanism leading to aneurysmal dilatations remains to be elucidated.

Programmed cell death (Apoptosis) and its role in the pathogenesis of lower extremity varicose veins

The etiology of varicose veins remains elusive. We hypothesized that abnormal cell cycle events in the vein wall may contribute to changes in its structural integrity predisposing to varicosity development. Since cell cycle checkpoint controls are linked to the signaling and execution of apoptotic cascades, possibly apoptosis is a contributing factor in the pathophysiology of varicosities. The present study was designed to investigate whether programmed cell death varies in varicosities as compared to normal veins. Twenty-seven normal greater saphenous vein specimens were obtained from patients undergoing infrainguinal arterial bypass surgery, and 20 varicose vein specimens were retrieved from patients undergoing varicose vein excision. Apoptosis was detected by TUNEL assay. Expression of bcl-2 and cyclin D1 was noted by standard immunohistochemical techniques. Apoptotic cells were identified in 32 of the 47 specimens. Forty-eight percent of normal vein specimens displayed >3 apoptotic cells per 100 cells in the adventitia; 15% of the specimens of the varicose vein group showed such magnitude of apoptosis (p < 0.03). This increased apoptotic activity was not observed in media or intima of either vein group (p < 0.001). No significant difference in immunoreactivity to bcl-2 protein was observed in varicose vein specimens as compared to controls. Varicose vein specimens demonstrated increased nuclear expression of cyclin D1 whereas its cytoplasmic expression was significantly diminished (p </=0.02). These data show that programmed cell death is inhibited in varicose veins. Differential expression of cyclin D1 suggests that it may deregulate cell cycle events, thereby leading to varicosity formation.

Tissue inhibitor of metalloproteinase-1 is increased in the saphenofemoral junction of patients with varices in the leg

PURPOSE

The goal of the present study was to examine the role of matrix metalloproteinase (MMP) activity in the development of varicose changes in the superficial veins of the lower extremity.

METHODS

Normal-caliber vein segments from the saphenofemoral junction were harvested from patients undergoing saphenous vein ligation for varices and from patients undergoing infrainguinal bypass graft procedures. The activity and quantity of MMPs and their inhibitors (tissue inhibitors of metalloproteinases [TIMPs]) in the vein segments were compared. Vein segments were obtained from 13 patients. Seven patients had varicose disease in the leg, including 6 women and 1 man (average age, 48 years). Six patients had no evidence of varicose disease, including 2 women and 4 men (average age, 59 years). Proteolytic activity was determined with substrate gel zymography, and enzyme content was determined with Western immunoblotting using monoclonal antibodies directed against MMP-2, MMP-3, MMP-9, TIMP-1, TIMP-2, and alpha2-macroglobulin. Signals were quantified by scanning densitometry and normalized to a positive control (densitometric index [DI]). Immunohistochemistry was performed for enzyme localization.

RESULTS

Zymography did not detect a difference between groups at loci consistent with the major MMPs; however, a small but significant decrease in proteolytic activity was noted in veins from patients with varices. TIMP-1 is increased in vein segments from patients with varices (DI 0.8 +/- 0.1 vs 0.2 +/- 0.05, P < .05) while MMP-2 levels were decreased (DI 1.5 +/- 0.3 vs 0.5 +/- 0.1, P < .05). Immunohistochemistry localized MMPs to the adventitia of the vein wall.

CONCLUSION

A decrease in proteolytic activity may be responsible for the histological and structural alterations leading to varicose degeneration of superficial lower extremity veins.

Retinoblastoma protein: a molecular regulator of chronic venous insufficiency

PURPOSE

Chronic venous insufficiency (CVI) and varicose vein (VV) formation is characterized histologically by the transformation of smooth muscle cells (SMC) from a contractile to a secretory phenotype and by intense collagen deposition. The subcellular regulation point for these processes may be the retinoblastoma protein (pRb), a known inhibitor of cellular proliferation and regulator of differentiation. We hypothesize that pRb phosphorylation is associated with VV formation and functions as a possible subcellular regulator.

METHODS

Patients were separated into two groups. Group 1 (n = 6) consisted of vein specimens obtained from patients undergoing coronary artery bypass grafting. Group 2 (n = 6) consisted of patients with symptomatic CVI and duplex confirmed refluxing greater saphenous veins (GSVs) who required GSV stripping. Western blots of GSV protein extracts were performed with anti-human pRb monoclonal antibodies and the degree of nonphosphorylated and phosphorylated pRb was determined. Results were quantified using image analysis of band intensities (computer calibrated intensity units). The ultrastructural appearance of SMCs and the vein wall architecture were qualitatively analyzed with electron microscopy in both groups.

RESULTS

Phosphorylated pRb from varicose GSVs exhibited intensities of 523 +/- 188 units, while phosphorylated pRb from normal GSVs demonstrated intensities of 153 +/- 41 units (P < 0.05). SMCs in varicosed GSVs were surrounded by disorganized collagen deposits and displayed a secretory phenotype with spherical vacuolated cells. SMCs from normal GSVs appeared spindle shaped with a purported contractile phenotype and a well-structured extracellular matrix.

CONCLUSION

Our data demonstrate that VV formation, in patients with CVI, is associated with phosphorylated pRb and the transformation of SMCs from a contractile to a secretory ultrastructural morphology. The data suggest that SMC dedifferentiation is regulated by pRb and the disinhibition of this protein (phosphorylation) may be an significant factor in the development of lower extremity varicosities.

Where does venous reflux start?

PURPOSE

This study was designed to identify the origin of lower limb primary venous reflux in asymptomatic young individuals and to compare patterns of reflux with age-matched subjects with prominent or clinically apparent varicose veins.

METHODS

Forty age- and sex-matched subjects with no symptoms (age, 15 to 35 years; 80 limbs; group A), 20 subjects (age, 19 to 32 years; 40 limbs) with prominent but nonvaricose veins (n = 26 limbs; group B), and 50 patients (age, 17 to 34 years; 100 limbs) with varicose veins (n = 64; group C) were examined with color flow duplex imaging. All proximal veins (above popliteal skin crease), superficial, perforator, and deep, in the lower limb were examined in the standing position, and all the distal veins in the sitting position. Patients who had a documented episode of superficial or deep vein thrombosis, previous venous surgery, or injection sclerotherapy were excluded from the study.

RESULTS

The prevalence of reflux in group A was 14% (11 of 80), in group B 77% (31 of 40), and in group C 87% (87 of 100). In more than 80% of limbs in the three groups, reflux was confined to the superficial veins alone. Deep venous reflux or combined patterns of reflux were uncommon even in group C. Reflux was detected in all segments of the saphenous veins and their tributaries. In the 125 limbs that had superficial venous incompetence, the below-knee segment of the greater saphenous vein was the most common site of reflux (85, 68%), followed by the above-knee segment of greater saphenous vein (69, 55%) and the saphenofemoral junction (41, 32%). Nonsaphenous reflux was rare (3, 2.4%). Reflux in the lesser saphenous vein (21, 17%) was seen in all groups, whereas involvement of both greater and lesser saphenous veins (8, 6.4%) was seen in group C alone. The incidence of multisegmental reflux was significantly higher in group C (61 of 64, 95%) than in group A (two of 11, 18%) or group B (14 of 26, 54%). The prevalence of distal reflux was comparable in all groups.

CONCLUSIONS

Primary venous reflux can occur in any superficial or deep vein of the lower limbs. The below-knee veins are often involved in asymptomatic individuals and in those who have prominent or varicose veins. These data suggest that reflux appears to be a local or multifocal process in addition to or separate from a retrograde process.

Increased mast cell infiltration in varicose veins of the lower limbs: a possible role in the development of varices

BACKGROUND

This study shows increased infiltration of mast cells in the walls of varicose veins in the lower limbs as an explanation of the pathogenesis of varix formation.

METHODS

Great saphenous veins exhibiting varicosity were histologically examined after vein stripping surgery, and the numbers of mast cells in the varicose lesions were estimated in 20 high-power fields (x400). Normal-looking regions of the veins were referred to as controls, and normal saphenous veins were prepared during coronary artery bypass grafting and designated baseline controls.

RESULTS

The varicose lesions showed a greater extent of mast cell infiltration (15.0 +/- 8.4 cells; mean +/- standard deviation), whereas control veins (5.9 +/- 4.0) and baseline control veins (4.4 +/-2.9) had a smaller number of mast cells.

CONCLUSIONS

The study suggests that increased mast cell infiltration contributes to the development of varicose veins.

Assessment of wall structure and composition of varicose veins with reference to collagen, elastin and smooth muscle content

OBJECTIVES

To compare collagen, elastin and smooth muscle contents of varicose and control long saphenous veins.

DESIGN

Collagen, elastin and muscle were estimated stereologically using random sampling and histological staining.

MATERIALS

Varicose vein samples were collected from nine patients (mean age 52 years, range 34-64 years) undergoing vein stripping, sample sites being saphenofemoral junction and knee. Control samples were taken from five patients (mean age 58 years, range 38-76 years) presenting for femoral-popliteal bypass at equivalent levels.

METHODS

Veins were fixed, sectioned transversely, and stained with Picric Acid Sirius Red. Analysis of samples was performed using point and intersection counting on vertically projected images.

RESULTS

Using two way analysis of variance tests, varicose saphenous veins had significantly larger wall areas (p < 0.01) and higher amounts of collagen (p < 0.01). Collagen content and wall area were significantly larger proximally compared to distally in both control and varicose veins (p < 0.05) with a higher content of smooth muscle and elastin in varicose veins proximally compared to distally (p < 0.05). There was no difference in wall thickness or elastin content between the two groups.

CONCLUSIONS

This suggests that varicose veins are a dynamic response to venous hypertension and are not thin walled structures as previously thought.

Morphological and morphometrical analysis of schistosomal granuloma degradation

In vivo degradation of the extracellular matrix of Schistosoma mansoni granulomas was morphologically studied by light and electron microscopy using 60 day-infected hepatic isolated and acellular granulomas (aPMC) which had been implanted into the subcutaneous tissue of syngenic albino mice and examined 4, 15, 20, 30 and 40 days after implantation. The progressive changes of aPMCs were estimated by measurements of aPMCs surface (micron2) on paraffin sections. After implantation, polymorphonuclear leukocytes were the initial population recruited whereas macrophages and fibroblasts were prominent in the late stages. Eosinophil leukocytes and in a lesser extent, mast cells increased in number. In electron microscopy, progressive disappearance of extracellular matrix and some modified collagen fibrils either in extracellular or intracellular localization represented matricial changes. The morphometrical analysis of aPMCs of the surface (micron2) after implantation showed a significant reduction of aPMCs (p < 0.001) in all stages after implantation. Polymorphonuclear cells, macrophages and fibroblasts seemed to be the major responsible cells involved in aPMCs resorption.

Occlusion of intra-acinar pulmonary arteries in pulmonary hypertensive congenital heart disease

Lung biopsy specimens from 10 consecutive cases of congenital heart disease and pulmonary hypertension (2 months-6.5 years) were examined by light and electron microscopy. By light microscopy, 8 cases showed a reduction in number of patent alveolar wall arteries associated with the structural features of early pulmonary vascular disease-extension of muscle, a significant increase in pulmonary arterial medial thickness (P less than 0.001) and little if any intimal proliferation (Heath & Edwards Grade I or II). In one additional child with Grade IV disease, arterial number could not be determined accurately. For all 10 cases, all blocks of tissue examined by light and electronmicroscopy showed absence of any lumen in structures identified as alveolar wall arteries by their position, shape and the presence of an external (or single) elastic lamina. In 3 additional similar cases, endothelial cells of narrowed and occluded arteries were marked by labelling with the lectin Ulex europaeus. Occluded arteries were identified consisting of mature smooth muscle cells and remnants of degenerating endothelial cells. Occlusion of alveolar wall arteries appears to be an early event in the development of pulmonary vascular disease, is associated with differentiation of smooth muscle cells in normally thin walled precapillary arteries and precedes significant obliterative intimal changes in more proximal vessels.

Mechanisms of tumor invasion: evidence from in vivo observations

The major mechanisms of tumor invasion in vivo are discussed in the present review. A special emphasis is placed on tumor dedifferentiation which has proved to be of paramount importance for the invasion process. Based on in vivo observations obtained from various human and animal tumors a concept for the mechanism of tumor invasion is proposed which mainly comprises the following basic events: the first and essential step in tumor invasion is the tumor dedifferentiation and dissociation at the invasion front. This apparently temporary and reversible process mobilizes the tumor cells out of the main tumor bulk and enables them to invade the host tissue by active locomotion. This mechanism is essentially supported by an interstitial edema in the host tissue adjacent to the tumor periphery, which causes an 'opening and widening' of the host intercellular spaces. Enzymatic changes in the micromilieu of the extracellular matrix may contribute to this process. The tumor cell proliferation completes the invasion process in so far, as the invading tumor cells are still able to proliferate, leading this way to expanding tumor cell nests in the host tissue which have the potency to redifferentiate. The expansive growth of these tumor cell nests results in a progressive atrophy of the host tissue, mainly caused by an increasing compression and a competitive withdrawal of oxygen and other nutrients by the tumor cells. The overall picture of tumor invasion can therefore be considered as a repetitive cycle of active tumor cell locomotion followed by focal tumor cell proliferation in the host tissue.