The marine Omega3 wound matrix for treatment of complicated wounds: A multicenter experience report.

INTRODUCTION: The Kerecis™ Omega3 Wound matrix is a decellularized skin matrix derived from fish skin and represents an innovative concept to achieve wound healing. The aim of this study was to report the cumulative experience of three centers for vascular surgery regarding use of the Omega3 Wound matrix in selected patients with complicated wounds. MATERIAL AND METHODS: In this study 23 patients with 25 vascular and/or diabetes mellitus-associated complicated wounds and partially exposed bony segments were treated with the Omega3 Wound matrix in three vascular centers. In several patients, conventional wound treatment with vacuum therapy had previously been carried out sometimes over several weeks without durable success. Following initial debridement in the operating room, the matrix was applied and covered with a silicone mesh. In the further course, wound treatment was conducted on an outpatient setting if possible. RESULTS: In total 25 wounds were treated with localization at the level of the thigh (n = 2), the distal calf (n = 7), the forefoot (n = 14) and the hand (n = 2). The time to heal varied between 9 and 41 weeks and between 3 and 26 wound matrices were applied per wound. Interestingly, a reduction of analgesics intake was noted when the treatment with the Omega3 Wound matrix was initiated. CONCLUSION: The novel Omega3 Wound matrix in this study represented an effective treatment option in 25 complicated wounds. Further studies are necessary to evaluate the impact of the wound matrix on stimulation of granulation tissue and re-epithelialization as well as the potential antinociceptive and analgetic effects.

[Autologous Bypass to Pedal Side Branches to Avoid a Major Amputation]. / Der autologe Bypass zu den pedalen Seitenästen zur Vermeidung der Majoramputation.

Background: In critical limb ischaemia (CLI), a pedal vein graft bypass offers good long-term results regarding function and limb salvage. However, some cases require bypasses to branches of pedal arteries based on angiographic findings. Methods: In a retrospective database we analysed all patients who received a vein graft bypass to branches of pedal arteries for treatment of critical limb ischaemia. Results: From January 1998 to June 2014 we performed bypasses to branches of pedal arteries in 72 patients (59 men and 13 women) out of a total of 534 patients who underwent pedal bypass surgery. The proximal bypass anastomosis was above the knee in 30 cases and below the knee in 42 patients. In 6 cases the bypass connection was made to the lateral tarsal artery, in 15 cases it was made to the lateral and in 24 cases to the medial plantar artery. In 27 patients a direct connection was made to the plantar bifurcation. All reconstructions were completely autologous. The limb salvage rate after 5 and 10 years was 82 %. Conclusion: A bypass to branches of pedal arteries is a procedure recommendable for limb salvage in cases of critical ischaemia where arteries with a larger diameter are no longer available.

[Omniflow-IITM for critical limb ischemia : Long-term results]. / Omniflow-IITM bei kritischer Extremitätenischämie : Langzeitergebnisse.

For the surgical treatment of critical limb ischemia one of the decisive influencing factors for short-term and long-term limb salvage is the use of autologous veins as bypass material. There is currently a lack of studies on the long-term assessment of alternative bypass materials, which can be used for critical limb ischemia due to a lack of autologous vein material. A prospective database was established that included all patients with critical limb ischemia who received a bypass with the Omniflow-II™ prosthesis. From 2006 until 2014 bypass surgery with the Omniflow-II™ prosthesis was carried out in 123 patients. The mortality was 5 % while the morbidity was 14 % and the 5­year survival rate was 37 %. In patients with a popliteal bypass (n = 62), the primary and secondary patency rates were 34 % and 69 %, respectively after 5 years. The corresponding results for the crural position (n = 61) over the same time period were 32 % and 34 %, respectively. After 5 years, the group receiving popliteal bypass surgery showed a limb salvage rate of 98 % whereas the crural group had a rate of 70 %. In this study we could demonstrate very promising results using the Omniflow-II™ prosthesis for the surgical treatment of critical limb ischemia.

[Propensity Score and Long-Term Survival Results after Open versus Endovascular Treatment of Abdominal Aortic Aneurysm]. / Propensity Score im Langzeitüberleben nach offener und endovaskulärer Therapie des Bauchaortenaneurysmas.

Background: There are not many publications on the long-term results of surgical treatment for abdominal aortic aneurysm (AAA) comparing open repair (OR) and endovascular aneurysm repair (EVAR). Method: Using a propensity score (PS), we matched cohorts which were eligible for both types of treatment and underwent an elective surgical procedure for infrarenal AAA between 2002 and 2008. The endpoint of the study was long-term survival without re-intervention. Results: From a total of 442 patients treated from 2002 to 2008, we identified 140 patients of whom 72 received a tube graft and 68 were treated by EVAR. Median observation time was 5 years (0.04-10.3). Mortality was zero in the EVAR group and 1 % in the OR group, with cumulative survival after 5 and 10 years being 82 (79 %) in the OR group and 80 (58 %) in the EVAR group. Three patients (4 %) out of 72 with open surgery and 23 patients (34 %) from the EVAR group had to undergo a repeat surgery. Conclusion: Both procedures are safe methods to eliminate aneurysms. However, the high rate of re-interventions or conversions in the EVAR group has to be considered in the selection of treatment.

Activation of the proapoptotic unfolded protein response in plaques of the human carotid artery.

OBJECTIVE: To analyze expression of keystone markers of apoptosis and the proapoptotic signaling pathway "unfolded protein response" (UPR) in rupture-prone plaques of the human carotid artery. METHODS: Plaque specimens were obtained during endarterectomy for high-grade carotid stenosis, and were formalin-fixed. Ten specimens were identified that exhibited criteria of advanced rupture-prone atherosclerotic plaques, and histological and immunohistological analysis of markers of apoptosis (cleaved Caspase-3, TUNEL) and UPR (KDEL, ATF3, CHOP, CHAC-1) was performed. In addition, co-localization of apoptosis and UPR-activation was assessed by double-immunohistochemistry. RESULTS: The mean size of the necrotic core was 44 ± 7% and the mean minimum/representative thicknesses of the fibrous cap were 129 ± 39 µm/280 ± 60 µm, respectively. Each specimen fulfilled at least two of the criteria for rupture-prone plaques. Semi-quantitative analysis of immunohistochemistry showed a significant increase in cleaved Caspase-3-positive (1923 ± 93 cells/mm(2)) and TUNEL-positive cells (1387 ± 66 cells/mm(2)) when compared with control tissue. Furthermore, expression of UPR-markers KDEL, AFT3 and CHOP was significantly increased (1175 ± 40 cells/mm(2), 1971 ± 69 cells/mm(2) and 2173 ± 120 cells/mm(2), respectively). Co-localization of UPR-activation with apoptosis was confirmed by double-immunohistochemistry, and lesional macrophages were identified as the primary cell-type involved. CONCLUSION: For the first time, activation of the proapoptotic signaling pathway UPR has been identified in advanced rupture-prone plaques of the human carotid artery. This provides additional evidence for adding UPR to the potential targets for controlling plaque apoptosis and thereby preventing plaque progression/rupture.

Long-term patency of open revascularization for visceral artery pathologies.

OBJECTIVE: Aim of the study was to evaluate the long-term patency of bypass grafts used to treat occlusive and aneurysmal disease of the visceral arteries. METHODS: A retrospective analysis of our vascular surgery database identified 30 patients (11 men, mean age 59 ± 14 years) who underwent 32 operations for visceral artery pathology between January 1995 and December 2009. Acute mesenteric ischemia (aMI) was present in 10, chronic mesenteric ischemia (cMI) in 14 and visceral artery aneurysm (VAn) in 7 cases. The primary endpoint of this study was vessel patency, secondary endpoints were survival and freedom from reintervention. RESULTS: A total of 46 vessels were revascularized (26 bypass grafts) and additional revascularization procedures (thromboembolectomy, patch plasty, transposition) were performed in 21 cases. In the perioperative period, 6 deaths (5 aMI, 1 cMI) occurred, resulting in a mortality rate of 50 % for aMI and 7 % for cMI. At long-term follow-up (55 months), 22 patients (100 % follow-up) were interviewed and 21 were scheduled for clinical and imaging examinations. Four vessel (3 grafts) occlusions were found in these patients. CONCLUSION: We were able to show that bypass grafting for a visceral artery pathology, although associated with an increased perioperative mortality, is a successful and durable procedure.

Long-term follow-up after endovascular treatment of acute aortic emergencies.

PURPOSE: To investigate the long-term outcome and efficacy of emergency treatment of acute aortic diseases with endovascular stent-grafts. METHODS: From September 1995 to April 2007, 37 patients (21 men, 16 women; age 53.9 +/- 19.2 years, range 18-85 years) with acute complications of diseases of the descending thoracic aorta were treated by endovascular stent-grafts: traumatic aortic ruptures (n = 9), aortobronchial fistulas due to penetrating ulcer or hematothorax (n = 6), acute type B dissections with aortic wall hematoma, penetration, or ischemia (n = 13), and symptomatic aneurysm of the thoracic aorta (n = 9) with pain, penetration, or rupture. Diagnosis was confirmed by contrast-enhanced CT. Multiplanar reformations were used for measurement of the landing zones of the stent-grafts. Stent-grafts were inserted via femoral or iliac cut-down. Two procedures required aortofemoral bypass grafting prior to stent-grafting due to extensive arteriosclerotic stenosis of the iliac arteries. In this case the bypass graft was used for introduction of the stent-graft. RESULTS: A total of 46 stent-grafts were implanted: Vanguard/Stentor (n = 4), Talent (n = 31), and Valiant (n = 11). Stent-graft extension was necessary in 7 cases. In 3 cases primary graft extension was done during the initial procedure (in 1 case due to distal migration of the graft during stent release, in 2 cases due to the total length of the aortic aneurysm). In 4 cases secondary graft extensions were performed--for new aortic ulcers at the proximal stent struts (after 5 days) and distal to the graft (after 8 months) and recurrent aortobronchial fistulas 5 months and 9 years after the initial procedure--resulting in a total of 41 endovascular procedures. The 30-day mortality rate was 8% (3 of 37) and the overall follow-up was 29.9 +/- 36.6 months (range 0-139 months). All patients with traumatic ruptures demonstrated an immediate sealing of bleeding. Patients with aortobronchial fistulas also demonstrated a satisfactory follow-up despite the necessity for reintervention and graft extension in 3 of 6 cases (50%). Two patients with type B dissection died due to mesenteric ischemia despite sufficient mesenteric blood flow being restored (but too late). Two suffered from neurologic complications, 1 from paraplegia and 1 from cerebral ischemia (probably embolic), 1 from penetrating ulcer, and 1 from persistent ischemia of the kidney. Five of 9 (56%) patients with symptomatic thoracic aneurysm demonstrated endoleaks during follow-up and there was an increase in the aneurysm in 1. CONCLUSION: Endovascular treatment is safe and effective for emergency treatment of life-threatening acute thoracic aortic syndromes. Results are encouraging, particularly for traumatic aortic ruptures. However, regular follow-up is mandatory, particularly in the other pathologies, to identify late complications of the stent-graft and to perform appropriate additional corrections as required.

Infrapopliteal composite bypass with autologous vein and second generation glutaraldehyde stabilized human umbilical vein (HUV) for critical lower limb ischaemia.

OBJECTIVE: To audit a single center consecutive series of infrapopliteal composite bypasses with second generation glutaraldehyde stabilized human umbilical vein. DESIGN: Retrospective study. PATIENTS: From January 1996 to July 2006 89 femoro-distal bypasses were constructed in 85 patients with HUV and residual vein segments as composite grafts in the absence of sufficient length of autologous vein. METHODS: All patients with infrainguinal bypass operations were registered prospectively. Bypasses to infrapopliteal arteries performed with HUV-composite grafts were reviewed for graft patency, limb salvage, patient survival and possible biodegeneration of the HUV. RESULTS: Early graft thrombosis was noted in 21.3%, necessitating revision surgery. Primary, primary assisted and secondary patency rates were 35%, 40% and 42% respectively, with a limb salvage rate of 87% after 5 years. Graft infection occurred in 7 limbs. Aneurysmal HUV graft degeneration was not detected by duplex scanning. CONCLUSION: HUV-composite bypasses provide acceptable patency and favorable limb salvage rates. Patency was similar to previous series using PTFE-composite bypasses but was significantly inferior to vein bypass. Possible biodegradation of the HUV grafts seems to be of minor clinical relevance.

Sequential femorodistal composite bypass with second generation glutaraldehyde stabilized human umbilical vein (HUV).

OBJECTIVE: To evaluate the performance of sequential composite bypasses with second generation glutaraldehyde stabilized human umbilical vein (HUV) and autologous vein. DESIGN: Retrospective study of consecutive patients, in a single centre. PATIENTS: From January 1998 to December 2003, 54 femoro-distal HUV-autologous vein sequential composite bypasses were constructed in 52 patients with critical leg ischemia and absence of sufficient length of autologous vein. METHODS: All infra-inguinal bypass operations were registered in a computerized database and prospectively followed. Bypasses using sequential HUV-composite technique were reviewed for graft patency, limb salvage and patient survival. RESULTS: Primary patency and secondary patency rates at 1, 2, 3 and 4 years were 71, 61, 53 and 53% and 89, 80, 73 and 67%, respectively. Corresponding limb salvage rates were 96, 92, 88 and 88%. Patient survival was 56% at 4 years. After 30 days additional procedures to maintain graft patency were necessary in six bypasses. Asymptomatic occlusion of one sequential anastomosis was found in five patients. CONCLUSION: Graft patency and limb salvage rate support the use of the sequential composite technique with second generation HUV in femorodistal bypass surgery, when autologous vein of sufficient length is not available.

[Limb salvage in diabetic foot syndrome with pedal bypass using the in-situ technique]. / Extremitätenerhalt durch pedalen In-situ-Bypass beim diabetischen Fusssyndrom.

INTRODUCTION: Treatment of the ischemic diabetic foot syndrome still represents a medical and economic challenge. Contrary to the aims of the Saint Vincent declaration a dramatic reduction of major amputations in Germany was not noted, although in the diabetic patients the predominant type of tibial artery occlusion allows construction of pedal bypasses for limb salvage. METHOD: In patients with ischemic diabetic foot syndrome following angiographic evaluation of the ischemic limb, the indication for surgical revascularisation of patent pedal arteries was established. The in-situ technique was preferred in the presence of a suitable ipsilateral greater saphenous vein whenever possible. Revascularisation was followed by treatment of foot ulcerations or, if necessary, minor amputations. Patients were followed by clinical examination and duplex scan investigation of the bypass in regular intervals. RESULTS: From 01/89 to 12/01 in 79 patients (59 men and 20 women) with non healing ulcerations or established gangrene from a total of 175 pedal bypasses 84 pedal bypass operations in 84 limbs were performed using the in-situ technique. All patients were diabetic and in addition 13.9% were dependent on hemodialysis for end stage renal disease. 59.5% of the bypasses originated from the popliteal artery (distal origin bypass). The dorsalis pedis artery was chosen for the distal anastomosis in 83% and the posterior tibial artery in 17%. Two patients (2.4%) died postoperatively from cardiac events. Early bypass occlusion occurred in 8.4% resulting in a major amputation rate of 6%. After 60 months primary, primary assisted and secondary patency was 67.7%, 71.5% and 75.3% respectively with a limb salvage rate of 78%. CONCLUSION: Pedal bypass using the in-situ technique provides excellent long term limb salvage rates in a disease with a generally unjustified bad prognosis with respect to limb salvage.

[Short distal origin vein graft in diabetic foot syndrome]. / Der kurze popliteodistale Venenbypass beim diabetischen Fusssyndrom DFS.

PURPOSE: World wide increase of diabetes compound with diabetic foot syndrome becomes a challenge in vascular surgery to avoid limb loss. In diabetics a special pattern of atherosclerosis is prevalent with disease limited to the infrageniculate arteries but sparing inflow vessels and distal tibial and pedal arteries. This provides short bypass grafting from popliteal to tibial and pedal arteries, a concept first described by F. Veith in 1981. METHODS: Diabetics with severe atherosclerotic disease and limb-threatening ischemia got general evaluation and vascular imaging. Falling in this special category the patients underwent short vein bypass grafting originating at the first or third popliteal segment extending to the tibial or pedal arteries. Follow up of patency and limb salvage was nearly complete. RESULTS: From 1988 to 2001 124 diabetics received 140 vein bypass grafts for limb salvage, 95.7% already preoperatively with foot necrosis. Operative mortality rate was 1.4%, major morbidity rate was 9.3%, early graft failure rate 8.5% and early amputation rate was 3.8%. 2 year primary patency, primary assisted patency, secondary patency rates and limb salvage were 73.3%, 75.7%, 76.4% and 87.2%. 5 years results were 63.6%, 69.2%, 70.0% and 81.9% respectively. DISCUSSION: This series revealed exceptionally good results in patients with diabetes mellitus after short vein bypass grafting in concert with earlier studies since 1981. Compared to long femorodistal grafts there was no difference in longterm patency. Bypass grafting in diabetic foot syndrome is still regarded to have a poor prognosis. Just the contrary is the case. This study in concert with former studies revealed distal origin bypass grafting a durable and effective procedure to fight limb loss in diabetic foot syndrome. CONCLUSION: Distal origin vein bypass grafting is an excellent method just for patients with diabetes. Looking at limb salvage rates over 80 % in 5 years, this procedure should be offered more often suitable patients with diabetic foot syndrome.

External reinforcement of varicose veins with PTFE prosthesis in infrainguinal bypass surgery -- clinical results.

OBJECTIVE: Segmental varicose degeneration of the autogenous greater saphenous vein may limit its use in infrainguinal bypass surgery. Wrapping a PTFE prosthesis around dilated veins has emerged as an option to create externally reinforced vein bypasses. Results regarding graft patency and limb salvage were analyzed. METHODS: Between September 1995 and January 2001, 35 infrainguinal bypass operations in 33 patients were performed with greater saphenous veins exhibiting segmental varicose dilatation. Grafts were followed by duplex scan and retrospective analysis of graft patency and limb salvage was performed. RESULTS: One bypass prompted successful revision for early occlusion. Four bypasses required additional reintervention during follow-up. 48 months primary, primary assisted and secondary patency rates were 66%, 82% and 82%, respectively, with a limb salvage rate of 97%. Duplex scan failed to demonstrate stenosis of the reinforced vein segments or aneurysmal degeneration of the residual vein. CONCLUSION: External reinforcement with a PTFE prosthesis allows the use of autogenous greater saphenous veins with varicose dilatation and enables the construction of all autogenous bypasses with promising graft patency and limb salvage.

Limb trauma with arterial injury: long-term performance of venous interposition grafts.

BACKGROUND: In contrast to arterial occlusive disease, data on long-term outcomes after vein grafts in limb trauma with arterial injury are sparse. PATIENTS: From 1991 through 2001, 22 trauma victims received 23 interposition vein grafts performed by an interdisciplinary team of trauma and vascular surgeons. Indications included both blunt and penetrating injuries with critical limb ischemia in the majority of cases. RESULTS: Operative treatment of the injured vessels (brachial n = 5, radial/ulnar n = 7, popliteal n = 6, tibial n = 3, pedal n = 2) encompassed venous interposition graft of either saphenous (n = 15) or cephalic vein (n = 8). All patients survived the operative procedure. 4 graft occlusions were noted and 3 major amputations had to be performed (one despite patent graft). 13 patients (76%) were available for duplex ultrasound examination after a mean follow-up of 59 months where patent grafts could be detected in all cases. CONCLUSION: A multidisciplinary approach ensures optimal treatment strategy of arterial injury in extremity trauma. Interposition vein grafts provide durable long-term results and should be attempted even in single-vessel injuries of forearm and lower leg.

Arterial embolism to the upper extremity in a patient with factor V Leiden mutation (APC resistance)--a case report and review of the literature.

Factor V Leiden mutation has emerged as one of the leading abnormalities in inherited blood coagulation disorders, resulting in a markedly increased risk for deep leg vein thrombosis. A 24-year-old woman presented with acute onset of critical ischemia of her left thumb and index finger. Intraarterial angiography revealed an embolus in the distal radial artery and a thrombotic occlusion of the digital artery of the thumb and index finger. Immediate therapy encompassed a selective surgical embolectomy of the distal radial artery followed by a local intraarterial lysis that was continued for 3 days. Additionally, therapeutic anticoagulation and vasodilating drugs (prostaglandin E) were administered. Within 2 days, capillary refill reappeared and the initial loss of sensory function at the tip of the thumb and index finger diminished. A screening test for thrombophilic disorders led to the diagnosis of a heterozygous mutation of factor V (Leiden mutation). Arterial thromboembolic events of factor V Leiden mutation are rare and have to date been described only in the supraaortic and coronary circulation. Therefore, the arterial embolism to the left hand presented in this report constitutes a rarity that could be successfully salvaged by the combined use of a vascular surgical procedure and intensified medical management.

Pedal arterial bypass for limb salvage in patients with diabetes mellitus.

OBJECTIVE: to evaluate pedal bypass grafting in patients with diabetes mellitus with critical limb ischaemia. PATIENTS AND METHOD: from 1994 to 1999, 49 consecutive pedal bypass grafts were performed in 46 patients with a median age of 69 years (range 37-85 years). The incidence of insulin-dependent diabetes mellitus was 87%. The distal anastomosis was located at the dorsalis pedis artery in 36, at the inframalleolar posterior tibial artery in 9 and at the plantar artery in 4 cases, respectively. RESULTS: one patient died perioperatively. Two bypass occlusions and one major amputation accounted for a primary patency rate of 96% and a limb salvage rate of 98% at 30 days, respectively. During a median follow-up of 28 months (range 1-70 months), 21 patients died of nonrelated causes. Three additional graft occlusions and 4 major amputations were noted resulting in a primary patency rate of 89% and a limb salvage rate of 87% at 48 months, respectively. CONCLUSION: Pedal bypass grafting utilising the greater saphenous vein with in-situ technique is a reliable and effective procedure to achieve durable limb salvage in patients with diabetes mellitus.

Endovascular treatment of acute bleeding complications in traumatic aortic rupture and aortobronchial fistula.

OBJECTIVE: Herein we report our experience in placement of endovascular stentgrafts in the descending aorta in patients with acute bleeding complications due to traumatic rupture or aortobronchial fistula. METHODS: Six patients (one woman, five men, mean age 47+/-19 years) were treated from September 1995 to February 2000 by implantation of endovascular stentgrafts in the descending aorta. Indications included traumatic ruptures of the aortic isthmus (n=3) and aortobronchial fistulas (n=3). All procedures were performed under general anaesthesia. The implants were introduced under fluoroscopic guidance via the aorta (n=1), the iliac (n=4) or femoral (n=2) artery, respectively. RESULTS: All aortobronchial fistulas and ruptures were sealed up successfully. There was no perioperative morbidity and no procedure-related morbidity except one patient who received aortofemoral reconstruction because of iliac occlusive disease. All patients are alive and well after a mean follow-up of 31 months (range 6-60). Two patients had recurrent hemoptysis, in one case, the patient received a second implant (distal extension), the other patient was managed conservatively. CONCLUSION: Endovascular treatment by a stentgraft is a safe and reliable procedure in the management of acute bleeding complications in patients with aortic rupture or aortobronchial fistulas.

Autogenous reconstruction of infected arterial prosthetic grafts utilizing the superficial femoral vein.

BACKGROUND: Prosthetic infection after reconstructive vascular surgery is a most serious complication, associated with high mortality and amputation rates. Following excision of the infected graft, several methods of reconstruction are available. We present here our experience with autogenous reconstruction of infected prosthetic arterial grafts using the superficial femoral vein (SFV). METHODS: From November 1995 to December 1999, we used the SFV in seven patients (mean age 70 years) for reconstruction of an infected aortobifemoral (n = 2), aortoiliac (n = 1), femorofemoral bypass (n = 1), femorotibial (n = 2) and carotid crossover bypass (n = 1). Treatment encompassed complete prosthetic excision and autogenous reconstruction with the SFV alone or as a spliced graft with the greater saphenous vein (GSV) or basilic vein. RESULTS: There were no perioperative deaths or amputations. Two patients exhibited transient moderate swelling of the donor limb. In the follow-up, six patients are alive and well without any signs of recurrent infection. One patient died with an unrelated cause 24 months postoperatively. All donor limbs were asymptomatic for venous congestion in the long-term follow-up. CONCLUSION: The SFV provides a reliable tool for autogenous reconstruction after resection of infected prosthetic arterial grafts. Harvesting the SFV is well tolerated as long as the deep femoral and the popliteal vein are preserved.

Complement activation by oxidatively modified low-density lipoproteins.

BACKGROUND: Oxidatively modified low-density lipoproteins (LDLs) have been implicated in the pathogenesis of atherosclerosis and are found in human vascular lesions. There is increasing evidence that complement activation may also play a role in atherogenesis. Activated complement proteins have been demonstrated to be present in early atherosclerotic lesions, and lipids isolated from lesions have been shown to activate complement, hence their designation as lesion complement activator (LCA). The question now arose whether oxidized LDLs would also activate complement. MATERIAL AND METHODS: The complement-activating capacity of a lesion complement activator preparation and of minimally as well as heavily oxidized LDL was investigated by measuring SC5b-9 formation in normal human serum. In addition, C3 conversion was followed using two-dimensional immunoelectrophoresis. RESULTS: Minimally and heavily oxidized LDL generated small but significant amounts of SC5b-9 (7.9 microgram mL-1, SD 3.5, and 10.8 microgram mL-1, SD 1.2, respectively; n = 6) compared with native LDL (3.3 microgram mL-1, SD 1.4; P < 0.05), whereas LCA generated substantially larger amounts of the terminal complex (32.0 microgram mL-1, SD 3.2). Both oxidized LDL preparations caused only minor C3 conversion. CONCLUSIONS: These findings show that oxidation does not confer relevant complement-activating properties on LDL, suggesting that the lesion complement activator is not directly related to oxidized LDL. Oxidized LDL is probably of minor importance for complement activation in atherosclerotic lesions.

Atherogenic properties of enzymatically degraded LDL: selective induction of MCP-1 and cytotoxic effects on human macrophages.

The mechanisms underlying the selective accumulation of macrophages in early atherosclerotic lesions are poorly understood but are likely to be related to specific properties of altered low density lipoprotein (LDL) deposited in the subendothelium. Enzymatic, nonoxidative degradation of LDL converts the lipoprotein to a potentially atherogenic moiety, enzymatically altered LDL (E-LDL), which activates complement and is rapidly taken up by human macrophages via a scavenger receptor-dependent pathway. Immunohistological evidence indicates that E-LDL is present in an extracellular location in the early lesion. We report that E-LDL causes massive release of monocyte chemotactic protein 1 (MCP-1) from macrophages and that expression of interleukin 8 or RANTES remains unchanged. Release of MCP-1 was preceded by a rapid expression of MCP-1 mRNA, which was detectable after 15 minutes, reached maximum levels after 1 hour, and remained detectable for 12 hours after exposure to concentrations as low as 10 microg/mL E-LDL. MCP-1 mRNA induction and protein release by E-LDL exceeded that evoked by oxidized LDL. Release of MCP-1 was dependent on de novo protein synthesis and on the activity of tyrosine kinases. At higher concentrations, E-LDL, but not oxidized LDL, exerted toxic effects on macrophages that in part appeared to be due to apoptosis. The results show that E-LDL possesses major properties of an atherogenic lipoprotein.

Immunohistochemical demonstration of enzymatically modified human LDL and its colocalization with the terminal complement complex in the early atherosclerotic lesion.

Treatment of low density lipoprotein (LDL) with degrading enzymes transforms the molecule to a moiety that is micromorphologically indistinguishable from lipoproteinaceous particles that are present in atherosclerotic plaques, and enzymatically modified LDL (E-LDL), but not oxidized LDL (ox-LDL), spontaneously activates the alternative complement pathway, as do lesion lipoprotein derivatives. Furthermore, because E-LDL is a potent inducer of macrophage foam cell formation, we propose that enzymatic degradation may be the key process that renders LDL atherogenic. In this article, we report the production of two murine monoclonal antibodies recognizing cryptic epitopes in human apolipoprotein B that become exposed after enzymatic attack on LDL. One antibody reacted with LDL after single treatment with trypsin, whereas recognition by the second antibody required combined treatment of LDL with trypsin and cholesterol esterase. In ELISAs, both antibodies reacted with E-LDL produced in vitro and with lesion complement activator derived from human atherosclerotic plaques, but they were unreactive with native LDL or ox-LDL. The antibodies stained E-LDL, but not native LDL or ox-LDL, that had been artificially injected into arterial vessel walls. With the use of these antibodies, we have demonstrated that early human atherosclerotic coronary lesions obtained at autopsy as well as lesions examined in freshly explanted hearts always contain extensive extracellular deposits of E-LDL. Terminal complement complexes, detected with a monoclonal antibody specific for a C5b-9 neoepitope, colocalized with E-LDL within the intima, which is compatible with the proposal that subendothelially deposited LDL is enzymatically transformed to a complement activator at the earliest stages in lesion development.