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Progenitor Mechanisms of Vascular Injury in Restenosis
Vol. 219, No. 3S, September 2014
The Clinical Impact of Restenosis After Femoropopliteal Stenting for Peripheral Arterial Occlusive Disease Huong Truong, Miguel Montero-Baker, MD, Bernardino C Branco, MD University of Arizona, Tucson, AZ INTRODUCTION: Restenosis after femoropopliteal stenting for peripheral arterial occlusive disease remains unclear. We investigated the clinical significance of velocity disturbances after endovascular treatment of femoropopliteal arterial disease with stent placement. METHODS: Vascular patients undergoing angioplasty with stent placement of the superficial femoral or popliteal arteries were enrolled over a 2-year period ending in 2013. Our institution’s surveillance includes clinic visits with duplex ultrasonography (DUS. Imaging and surgical reinterventions performed for each patient were tabulated. Restenosis was defined as peak systolic velocity (PSV) >200 cm/s or velocity ratio (VR) >2.5. RESULTS: There were 112 femoropopliteal lesions treated with stents in 97 patients. 59.8% were male and the mean age was 69.3 years. 32.6% were TASC2 A, 37.2% B, 14.0% C and 16.2% D. During a mean follow-up of 467.5 days, twenty (20.6%) patients developed restenosis detected by DU and 15 (15.5%) progressed to occlusion. Overall, 6 (30.0%) were asymptomatic and were observed based on clinical grounds. 14 (70.0%) were symptomatic restenosis of which 9 (45.0%) underwent reintervention for recurrent disease. Overall, there were 7 amputations in this cohort all but one occurring in the restenotic group. All restenotic lesions progressing to occlusion demonstrated increased flow velocities up to 300cm/s within the first month after stent placement. CONCLUSIONS: In this evaluation, restenosis was a common endpoint occurring in approximately 20% of patients treated with stent placement. The presence of high flow velocities within the first month of treatment was associated with progression to occlusion. This patient population may benefit from early aggressive reintervention as limb loss rates are high in the occluded group. Laser-Targeted Occlusion Of Microvessels Induces Compensatory Intussusceptive Angiogenesis Janeil M Belle, MD, Grace S Lee, MD, Alexandra B Ysasi, Robert D Bennett, MD, FACS, Maximillian Ackermann, MD, Willi L Wagner, Moritz A Konerding, MD, Akira Tsuda, PhD, Steven J Mentzer, MD, FACS Brigham and Women’s Hospital, Boston, MA INTRODUCTION: Microvascular beds are known to undergo vessel-specific and, less well-described, network-level structural changes in response to hemodynamic stimuli. The influence of local hemodynamic forces on vascular architecture remains a central problem in the understanding of angiogenesis. We altered capillary plexus inflow and outflow in the chick chorioallanotic membrane (CAM) using vascular laser-targeted occlusion (LTO) to test predictions of a role of intussusceptive angiogenesis (IA)
Surgical Forum Abstracts
S159
in the microvasculature in response to changes in volumetric blood flow. METHODS: Intravascular blood flow was selectively abolished in low order, extra-capillary arterial and venous vessels of ex ovo CAMs. Target vessels were irradiated with a 670 nm diode laser at 0.3-0.6J after AlPcS4 photosensitizer perfusion, until cessation of flow occurred. Intravital fluorescent videomicroscopy (IFVM), speckle displacement velocimetry and digital kymography were used to evaluate local flow changes. IFVM was used to examine structural and angiogenic changes in area vessels after blood flow alteration. RESULTS: Target extracapillary vessels, 35-90 mm diameter, were selectively occluded by LTO. In arterial occlusions, post-LTO kymography evidenced lack of flow in vessels within 421.959.8 mm of the LTO site. At 36-60 hours, perfused vessel segments were visualized on IFVM within previously non-perfused areas observed immediately after arterial LTO. Numerous transluminal pillars were seen in the perfused vessel segments. CONCLUSIONS: Selective laser-targeted occlusion of low-order vessels can alter differential flow in the CAM capillary plexus. Arterial LTO findings suggest IA may be involved in the restoration of local blood flow after photo-occlusion. Continued investigation of blood flow dynamics in the microvasculature may aid in understanding angioadaptive processes. Progenitor Mechanisms of Vascular Injury in Restenosis Bryan W Tillman, MD, PhD, FACS, Tara D Richards, BS, Alex Chen, MD, PhD, Albert D Donnenberg, PhD, Vera Donnenberg, PhD University of Pittsburgh Medical Center, Pittsburgh, PA INTRODUCTION: Circulating progenitor cells have been implicated as an important participant in restenotic pathology. Based on findings of a progenitor surge specific to macrovascular injury, we hypothesized that an antibody based depletion would reduce both progenitors and restenosis in a murine model. Vascular injury signals overlap with pathways for progenitor mobilization and reduced restenosis is observed among animals with knockout of the injury signal MMP9 (MMP9KO), we reasoned that the mechanism may be related to impaired progenitor surge. METHODS: C57BL6 mice underwent injury of the femoral artery after antibody treatment towards the progenitor marker sca-1 or a control. Blood was examined using flow cytometry for CD34+/ckit+ progenitor cells. Separately, antibody treated animals underwent vessel explant at 28 days with determination of intima to media (I/M) ratio. Finally, a group of animals with knockout of MMP9KO were examined by flow cytometry after vascular injury. RESULTS: Wire injury among isotype treated animals generated a surge of progenitor cells relative to non-surgical controls (p¼ 0.004). Treatment with sca1 antibody effectively ablated the surge, compared to isotype treated, wire injured animals (p¼ 0.02). Twenty eight days after wire injury, sca progenitor depletion
S160
J Am Coll Surg
Surgical Forum Abstracts
reduced the I/E ratio in a statistically significant fashion (p¼0.04). We further identified that mice with deficits in MMP9 (MMP9KO) revealed absent progenitor surge after vascular injury. CONCLUSIONS: We have demonstrated that sca-1 antibody reduces both progenitor surge and vascular restenosis. Impaired progenitor surge in the setting of defective vascular injury signaling (MMP9) further suggests that circulating progenitors may serve an active role in restenotic pathology. Risk-Stratified Analysis of Open vs Fenestrated Repair of Complex Abdominal Aortic Aneurysms Robert T Lancaster, MD, MPH, Eric Twerdahl, MD, Jahan Mohebali, MD, Emel Ergul, MS, Christopher J Kwolek, MD, Mark F Conrad, MD, MMSc, Richard P Cambria, MD, FACS, Virendra I Patel, MD, MPH Massachusetts General Hospital, Boston, MA INTRODUCTION: Commercial availability of fenestrated stent grafts (FEVAR) in the US has expanded options for patients with complex (juxtarenal or suprarenal) abdominal aortic aneurysms (CAA). This study evaluates outcomes of open vs FEVAR repair of CAA using the NSQIP database.
respectively. The comparative outcomes of open vs FEVAR by risk strata are presented in Table 1. CONCLUSIONS: Favorable outcomes for FEVAR observed in high risk patients likely reflects differences in clinical presentation, however this analysis of early experience with FEVAR suggests comparable outcomes for open and FEVAR repair in low and intermediate risk patients. Electrospun Poly(ester urethane) Urea Dressings Improve Wound Healing in Diabetic Mice Christopher B Washington, MD, Sang-Ho Ye, PhD, Hirokazu Sakaguchi, PhD, Ankur J Shukla, MD, William R Wagner, Edith Tzeng, MD, FACS University of Pittsburgh, Pittsburgh, PA INTRODUCTION: Non-healing wounds are a major source of morbidity in the diabetic population. Poly(ester urethane) urea (PEUU) is a biodegradable, elastic polymer that has been previously shown to promote myocardial remodeling after infarction by supporting ingrowth of cardiac myocytes. We hypothesize that electrospun PEUU may similarly support cutaneous cellular ingrowth and improve diabetic wound healing.
METHODS: The NSQIP Participant Use File (2012) was queried by CPT code to identify patients undergoing open repair or FEVAR. A previously developed/validated risk scoring system was re-validated using open and FEVAR patients. It was used to assign CAA patients into risk strata and outcomes of open and FEVAR repair were analyzed by patient risk.
METHODS: Diabetic Db/Db mice were anesthetized and 1 x 1 cm excisional wounds were created. Control mice (n ¼ 6) were treated with biooclusive dressings while treatment mice (n ¼ 7) had PEUU patches sutured over the wounds. Wound areas were quantified at day 14 by digital planimetry. After sacrifice, wound beds were analyzed histologically and by immunostaining for proliferation (Ki67) and angiogenesis (CD31).
RESULTS: This study included 294 open and 165 FEVAR repairs. FEVAR patients were older (769 yrs. vs 719; p<0.01), had PVD (18% vs 7%9; p¼0.03), and did not have rupture (0% vs 19%; p<0.01). FEVAR had shorter OR time (200130min. vs 270 130; p<0.01) and length of stay (median 3 vs 8d; p<0.01). FEVAR configurations involved 0 (71%), 1 (8%), 2(2%), or 3(19%) visceral stents. Our risk prediction model had excellent fit to open and FEVAR patients (AUC¼0.87). There were 39%(n¼177), 41%(187), and 20%(95) low, intermediate, and high risk patients
RESULTS: PEUU treated wounds were significantly smaller than control wounds at day 14 (Table). There appeared to be less wound contraction compared to control wounds. H&E staining of the wound bed showed keratinocyte and epidermal growth in the center of the wound in PEUU mice and no regeneration in the control animals. Immunostaining with Ki67 revealed increased proliferation of basal keratinocytes in the PEUU wounds. CD 31 staining showed angiogenesis in the tissues surrounding the polymer but no difference in number between treatment groups. Table. Effect of PEUU patches on diabetic wound healing
Table 1. Outcomes of open and FEVAR by risk strata OPEN (n¼117) FEVAR (n¼60) p Value
Low risk, n Death Renal complications Moderate risk, n Death Renal complications High risk, n Death Renal complications
117 1% 5% 107 7.5% 8% 70 40% 26%
60 0 2% 80 8.7% 3% 25 4% 4%
1 0.4 0.8 0.1 <0.01 0.02
Treatment
Control PEUU patch p Value (t-test)
Wound area (% of original wound)
Proliferation (%Ki67 positive cells)
Angiogenesis (no. CD31 positive structures)
46.6 4.1
10.6 4.1
110.61 54.2
19.4 2.4
35.5 2.9
185.87 84.1
0.0004
0.002
0.533
CONCLUSIONS: PEUU patches accelerated wound healing in diabetic mice with improved regeneration of the epidermis and keratinocyte proliferation. PEUU wound dressings represent a novel
The Clinical Impact of Restenosis After Femoropopliteal Stenting for Peripheral Arterial Occlusive Disease Huong Truong, Miguel Montero-Baker, MD, Bernardino C Branco, MD University of Arizona, Tucson, AZ INTRODUCTION: Restenosis after femoropopliteal stenting for peripheral arterial occlusive disease remains unclear. We investigated the clinical significance of velocity disturbances after endovascular treatment of femoropopliteal arterial disease with stent placement. METHODS: Vascular patients undergoing angioplasty with stent placement of the superficial femoral or popliteal arteries were enrolled over a 2-year period ending in 2013. Our institution’s surveillance includes clinic visits with duplex ultrasonography (DUS. Imaging and surgical reinterventions performed for each patient were tabulated. Restenosis was defined as peak systolic velocity (PSV) >200 cm/s or velocity ratio (VR) >2.5. RESULTS: There were 112 femoropopliteal lesions treated with stents in 97 patients. 59.8% were male and the mean age was 69.3 years. 32.6% were TASC2 A, 37.2% B, 14.0% C and 16.2% D. During a mean follow-up of 467.5 days, twenty (20.6%) patients developed restenosis detected by DU and 15 (15.5%) progressed to occlusion. Overall, 6 (30.0%) were asymptomatic and were observed based on clinical grounds. 14 (70.0%) were symptomatic restenosis of which 9 (45.0%) underwent reintervention for recurrent disease. Overall, there were 7 amputations in this cohort all but one occurring in the restenotic group. All restenotic lesions progressing to occlusion demonstrated increased flow velocities up to 300cm/s within the first month after stent placement. CONCLUSIONS: In this evaluation, restenosis was a common endpoint occurring in approximately 20% of patients treated with stent placement. The presence of high flow velocities within the first month of treatment was associated with progression to occlusion. This patient population may benefit from early aggressive reintervention as limb loss rates are high in the occluded group. Laser-Targeted Occlusion Of Microvessels Induces Compensatory Intussusceptive Angiogenesis Janeil M Belle, MD, Grace S Lee, MD, Alexandra B Ysasi, Robert D Bennett, MD, FACS, Maximillian Ackermann, MD, Willi L Wagner, Moritz A Konerding, MD, Akira Tsuda, PhD, Steven J Mentzer, MD, FACS Brigham and Women’s Hospital, Boston, MA INTRODUCTION: Microvascular beds are known to undergo vessel-specific and, less well-described, network-level structural changes in response to hemodynamic stimuli. The influence of local hemodynamic forces on vascular architecture remains a central problem in the understanding of angiogenesis. We altered capillary plexus inflow and outflow in the chick chorioallanotic membrane (CAM) using vascular laser-targeted occlusion (LTO) to test predictions of a role of intussusceptive angiogenesis (IA)
Surgical Forum Abstracts
S159
in the microvasculature in response to changes in volumetric blood flow. METHODS: Intravascular blood flow was selectively abolished in low order, extra-capillary arterial and venous vessels of ex ovo CAMs. Target vessels were irradiated with a 670 nm diode laser at 0.3-0.6J after AlPcS4 photosensitizer perfusion, until cessation of flow occurred. Intravital fluorescent videomicroscopy (IFVM), speckle displacement velocimetry and digital kymography were used to evaluate local flow changes. IFVM was used to examine structural and angiogenic changes in area vessels after blood flow alteration. RESULTS: Target extracapillary vessels, 35-90 mm diameter, were selectively occluded by LTO. In arterial occlusions, post-LTO kymography evidenced lack of flow in vessels within 421.959.8 mm of the LTO site. At 36-60 hours, perfused vessel segments were visualized on IFVM within previously non-perfused areas observed immediately after arterial LTO. Numerous transluminal pillars were seen in the perfused vessel segments. CONCLUSIONS: Selective laser-targeted occlusion of low-order vessels can alter differential flow in the CAM capillary plexus. Arterial LTO findings suggest IA may be involved in the restoration of local blood flow after photo-occlusion. Continued investigation of blood flow dynamics in the microvasculature may aid in understanding angioadaptive processes. Progenitor Mechanisms of Vascular Injury in Restenosis Bryan W Tillman, MD, PhD, FACS, Tara D Richards, BS, Alex Chen, MD, PhD, Albert D Donnenberg, PhD, Vera Donnenberg, PhD University of Pittsburgh Medical Center, Pittsburgh, PA INTRODUCTION: Circulating progenitor cells have been implicated as an important participant in restenotic pathology. Based on findings of a progenitor surge specific to macrovascular injury, we hypothesized that an antibody based depletion would reduce both progenitors and restenosis in a murine model. Vascular injury signals overlap with pathways for progenitor mobilization and reduced restenosis is observed among animals with knockout of the injury signal MMP9 (MMP9KO), we reasoned that the mechanism may be related to impaired progenitor surge. METHODS: C57BL6 mice underwent injury of the femoral artery after antibody treatment towards the progenitor marker sca-1 or a control. Blood was examined using flow cytometry for CD34+/ckit+ progenitor cells. Separately, antibody treated animals underwent vessel explant at 28 days with determination of intima to media (I/M) ratio. Finally, a group of animals with knockout of MMP9KO were examined by flow cytometry after vascular injury. RESULTS: Wire injury among isotype treated animals generated a surge of progenitor cells relative to non-surgical controls (p¼ 0.004). Treatment with sca1 antibody effectively ablated the surge, compared to isotype treated, wire injured animals (p¼ 0.02). Twenty eight days after wire injury, sca progenitor depletion
S160
J Am Coll Surg
Surgical Forum Abstracts
reduced the I/E ratio in a statistically significant fashion (p¼0.04). We further identified that mice with deficits in MMP9 (MMP9KO) revealed absent progenitor surge after vascular injury. CONCLUSIONS: We have demonstrated that sca-1 antibody reduces both progenitor surge and vascular restenosis. Impaired progenitor surge in the setting of defective vascular injury signaling (MMP9) further suggests that circulating progenitors may serve an active role in restenotic pathology. Risk-Stratified Analysis of Open vs Fenestrated Repair of Complex Abdominal Aortic Aneurysms Robert T Lancaster, MD, MPH, Eric Twerdahl, MD, Jahan Mohebali, MD, Emel Ergul, MS, Christopher J Kwolek, MD, Mark F Conrad, MD, MMSc, Richard P Cambria, MD, FACS, Virendra I Patel, MD, MPH Massachusetts General Hospital, Boston, MA INTRODUCTION: Commercial availability of fenestrated stent grafts (FEVAR) in the US has expanded options for patients with complex (juxtarenal or suprarenal) abdominal aortic aneurysms (CAA). This study evaluates outcomes of open vs FEVAR repair of CAA using the NSQIP database.
respectively. The comparative outcomes of open vs FEVAR by risk strata are presented in Table 1. CONCLUSIONS: Favorable outcomes for FEVAR observed in high risk patients likely reflects differences in clinical presentation, however this analysis of early experience with FEVAR suggests comparable outcomes for open and FEVAR repair in low and intermediate risk patients. Electrospun Poly(ester urethane) Urea Dressings Improve Wound Healing in Diabetic Mice Christopher B Washington, MD, Sang-Ho Ye, PhD, Hirokazu Sakaguchi, PhD, Ankur J Shukla, MD, William R Wagner, Edith Tzeng, MD, FACS University of Pittsburgh, Pittsburgh, PA INTRODUCTION: Non-healing wounds are a major source of morbidity in the diabetic population. Poly(ester urethane) urea (PEUU) is a biodegradable, elastic polymer that has been previously shown to promote myocardial remodeling after infarction by supporting ingrowth of cardiac myocytes. We hypothesize that electrospun PEUU may similarly support cutaneous cellular ingrowth and improve diabetic wound healing.
METHODS: The NSQIP Participant Use File (2012) was queried by CPT code to identify patients undergoing open repair or FEVAR. A previously developed/validated risk scoring system was re-validated using open and FEVAR patients. It was used to assign CAA patients into risk strata and outcomes of open and FEVAR repair were analyzed by patient risk.
METHODS: Diabetic Db/Db mice were anesthetized and 1 x 1 cm excisional wounds were created. Control mice (n ¼ 6) were treated with biooclusive dressings while treatment mice (n ¼ 7) had PEUU patches sutured over the wounds. Wound areas were quantified at day 14 by digital planimetry. After sacrifice, wound beds were analyzed histologically and by immunostaining for proliferation (Ki67) and angiogenesis (CD31).
RESULTS: This study included 294 open and 165 FEVAR repairs. FEVAR patients were older (769 yrs. vs 719; p<0.01), had PVD (18% vs 7%9; p¼0.03), and did not have rupture (0% vs 19%; p<0.01). FEVAR had shorter OR time (200130min. vs 270 130; p<0.01) and length of stay (median 3 vs 8d; p<0.01). FEVAR configurations involved 0 (71%), 1 (8%), 2(2%), or 3(19%) visceral stents. Our risk prediction model had excellent fit to open and FEVAR patients (AUC¼0.87). There were 39%(n¼177), 41%(187), and 20%(95) low, intermediate, and high risk patients
RESULTS: PEUU treated wounds were significantly smaller than control wounds at day 14 (Table). There appeared to be less wound contraction compared to control wounds. H&E staining of the wound bed showed keratinocyte and epidermal growth in the center of the wound in PEUU mice and no regeneration in the control animals. Immunostaining with Ki67 revealed increased proliferation of basal keratinocytes in the PEUU wounds. CD 31 staining showed angiogenesis in the tissues surrounding the polymer but no difference in number between treatment groups. Table. Effect of PEUU patches on diabetic wound healing
Table 1. Outcomes of open and FEVAR by risk strata OPEN (n¼117) FEVAR (n¼60) p Value
Low risk, n Death Renal complications Moderate risk, n Death Renal complications High risk, n Death Renal complications
117 1% 5% 107 7.5% 8% 70 40% 26%
60 0 2% 80 8.7% 3% 25 4% 4%
1 0.4 0.8 0.1 <0.01 0.02
Treatment
Control PEUU patch p Value (t-test)
Wound area (% of original wound)
Proliferation (%Ki67 positive cells)
Angiogenesis (no. CD31 positive structures)
46.6 4.1
10.6 4.1
110.61 54.2
19.4 2.4
35.5 2.9
185.87 84.1
0.0004
0.002
0.533
CONCLUSIONS: PEUU patches accelerated wound healing in diabetic mice with improved regeneration of the epidermis and keratinocyte proliferation. PEUU wound dressings represent a novel