Long-term Results With CorMatrix Extracellular Matrix Patches After Carotid Endarterectomy.

BACKGROUND: Previous reports of extracellular matrix (ECM) patch use after carotid endarterectomy (CEA) have noted an approximately 10% rate of pseudoaneurysm (PSA) formation. PSA-related rupture of ECM patches has also been described after femoral artery repair. In these studies, different thicknesses (4-ply versus 6-ply) and no standard length of soaking the patch in saline before implantation were used. Herein, we describe our experience with ECM CorMatrix patches in 291 CEAs with 6-ply patches. METHODS: The records of 275 consecutive patients undergoing 291 CEAs with CorMatrix 6-ply patches beginning in November of 2011 and extending until 2015 were reviewed. Only 6-ply patches and a 1 min hydration time in saline were used in all patients. No shunts were used. RESULTS: There were three deaths within the first 30 d secondary to subsequent cardiac surgical procedures. Nine patients experienced a perioperative stroke (3.1%), only one of which occurred secondary to an occluded internal carotid artery. One patient had a transient ischemic attack with a patent endarterectomy site. In follow-up, 11 patients (4.5%) developed severe recurrent stenoses requiring reintervention. Only one patient (0.34%) developed a PSA at 2 years possibly secondary to chronic infection. The median follow-up was 72 mo. CONCLUSIONS: Our experience with 6-ply CorMatrix ECM patches and a brief period of soaking demonstrated that these patches performed well in patients requiring a CEA. Only one PSA was noted.

Adult venous endothelium is a niche for highly proliferative and vasculogenic endothelial colony-forming cells.

OBJECTIVE: Postnatal resident endothelium of blood vessels has been proposed to represent terminally differentiated tissue that does not replicate. We previously isolated endothelial colony-forming cells (ECFCs) from human umbilical cord blood (CB) and term placenta by using colony-forming assays and immunocytochemistry. We showed that ECFCs are highly proliferative and form functioning vessels in vivo, the defining characteristics of a true endothelial progenitor cell. This exploratory investigation was conducted to determine whether the endothelium of healthy adult blood vessels contained resident ECFCs. METHODS: The endothelium of great saphenous vein (GSV) obtained from vein stripping procedures was collected with mechanical scraping, and ECFCs were isolated according to established protocols. RESULTS: GSV ECFCs incorporated acetylated low-density lipoprotein, formed tubules in Matrigel (BD Biosciences, San Jose, Calif) at 24 hours, and expressed endothelial antigens cluster of differentiation (CD) 144, CD31, CD105, and kinase insert domain receptor but not hematopoietic antigen CD45. Using cumulative population doublings and single-cell assays, we demonstrated that GSV ECFCs exhibited comparable proliferative capacities compared with CB ECFCs, including similar numbers of highly proliferative cells. When injected in collagen/fibronectin gels implanted in nonobese diabetic/severe combined immune deficiency mice, GSV ECFCs formed blood vessels with circulating murine red blood cells, demonstrating their vasculogenic potential. CONCLUSIONS: The ECFCs of the GSV contain a hierarchy of progenitor cells with a comparable number of highly proliferative clones as ECFCs of CB. The results of this investigation demonstrate that the adult endothelium contains resident progenitor cells that may have a critical role in vascular homeostasis and repair and could potentially be used as a source of autologous cells for cell therapies focusing on vasculogenesis.

Differentiation of human pluripotent stem cells to cells similar to cord-blood endothelial colony-forming cells.

The ability to differentiate human pluripotent stem cells into endothelial cells with properties of cord-blood endothelial colony-forming cells (CB-ECFCs) may enable the derivation of clinically relevant numbers of highly proliferative blood vessel-forming cells to restore endothelial function in patients with vascular disease. We describe a protocol to convert human induced pluripotent stem cells (hiPSCs) or embryonic stem cells (hESCs) into cells similar to CB-ECFCs at an efficiency of >10(8) ECFCs produced from each starting pluripotent stem cell. The CB-ECFC-like cells display a stable endothelial phenotype with high clonal proliferative potential and the capacity to form human vessels in mice and to repair the ischemic mouse retina and limb, and they lack teratoma formation potential. We identify Neuropilin-1 (NRP-1)-mediated activation of KDR signaling through VEGF165 as a critical mechanism for the emergence and maintenance of CB-ECFC-like cells.

Management of vascular trauma from dog bites.

BACKGROUND: Vascular trauma from large-dog bites present with a combination of crush and lacerating injuries to the vessel, as well as significant adjacent soft tissue injury and a high potential for wound complications. This retrospective case series evaluates our 15 years of experience in managing this uncommonly seen injury into suggested treatment recommendations. METHODS: From our database, 371 adult patients presented with dog bites between July 1997 and June 2012. Twenty (5.4%) of those patients had vascular injuries requiring surgical intervention. Patient demographics, anatomic location of injury, clinical presentation, imaging modality, method of repair, and complication rates were reviewed to assess efficacy in preserving limb function. Pediatric patients were managed at the regional children's hospital and, therefore, not included in this study. RESULTS: Among the 20 surgically treated vascular injuries, there were 13 arterial-only injuries, two venous-only injuries, and five combination arterial and venous injuries. Seventeen patients (85%) had upper extremity injuries; three patients had lower extremity injuries (15%). The axillobrachial artery was the most commonly injured single vessel (n = 9/20; 45%), followed by the radial artery (n = 4/20; 20%). Surgical repair of vascular injuries consisted of resection and primary anastomosis (four), interposition bypass of artery with autogenous vein (13), and ligation (two), with (one) being a combination of bypass and ligation. All patients had debridement of devitalized tissue combined with pulse lavage irrigation and perioperative antibiotics. Associated injuries requiring repair included muscle and skin (n = 10/20; 50%), bone (n = 1/20; 5%), nerve (n = 1/20; 5%), and combinations of the three (n = 5/20; 25%). Postoperative antibiotic therapy was administered for 14.7 ± 8.2 days in all 20 patients. Four patients (20%) developed postoperative wound infections, although this did not compromise their vascular repair. Of the patients compliant with postoperative surveillance, all limbs (100%) were viable at discharge and at 1-year follow-up. CONCLUSIONS: Dog bite vascular injuries are an uncommon occurrence, where extremity pulse abnormalities are the most common presentation. These injuries are also associated with significant adjacent soft tissue trauma, which warrants aggressive debridement and perioperative antibiotic therapy. Despite vigilant management, nearly one-fifth of our patients sustained wound infections. All infections were successfully managed with broad-spectrum antibiotics, and all limbs were preserved 1-year postoperatively.

Single-port laparoscopic right hemicolectomy: the first 100 resections.

BACKGROUND: Single-port laparoscopy remains a novel technique in the field of colorectal surgery. Several small series have examined its safety for colon resection. OBJECTIVE: Our aim was to analyze our entire experience and short-term outcomes with single-port laparoscopic right hemicolectomy since its introduction at our institution. We assert that this approach is feasible and safe for the wide array of patients and indications encountered by a colorectal surgeon. DESIGN: This is a retrospective analysis of prospectively gathered data for all patients who underwent single-port laparoscopic right hemicolectomy with the use of standard laparoscopic instrumentation, for malignant or benign disease, between July 2009 and November 2010 in a high-volume, academic, colorectal surgery practice. MAIN OUTCOME MEASURES: Demographic, clinical, operative, and pathologic factors were reviewed and analyzed. All conversions to conventional laparoscopic or open operations were considered in this analysis. RESULTS: One hundred patients underwent single-port laparoscopic right hemicolectomy during the study period. Mean age was 63 years, and 61% of the patients were men. Forty-three percent had undergone previous abdominal surgery, and the median body mass index was 26 (range, 18-46). Median ASA classification was 3 (range, 1-4). Five percent of the operations were performed urgently, and 56% were performed for carcinoma, of which half were T3 or T4 tumor stage. Median operative duration was 105 (range, 64-270) minutes. Mean and median blood loss was 106 and 50 mL. Two percent required conversion to multiport laparoscopy, and 4% converted to the open approach. Median postoperative stay was 4 (range, 2-48) days. Median lymph node number was 18 (range, 11-42). There was one mortality in this series. Morbidity, including wound infection, was 13%. CONCLUSIONS: This represents the largest experience with single-port laparoscopic right hemicolectomy to date. This technique was used with acceptable morbidity and mortality and without compromise of conventional oncologic parameters by colorectal surgeons experienced in minimally invasive technique. These findings support the use of a single-port approach for patients requiring right hemicolectomy.

Resident Endothelial Progenitor Cells From Human Placenta Have Greater Vasculogenic Potential Than Circulating Endothelial Progenitor Cells From Umbilical Cord Blood.

Endothelial colony-forming cells (ECFCs) isolated from umbilical cord blood (CBECFCs) are highly proliferative and form blood vessels in vivo. The purpose of this investigation was to isolate and characterize a population of resident ECFCs from the chorionic villi of term human placenta and provide a comparative analysis of their proliferative and vasculogenic potential with CBECFCs. ECFCs were isolated from umbilical cord blood and chorionic villi from placentas obtained by caesarean deliveries. Placental ECFCs (PECFCs) expressed CD144, CD31, CD105, and KDR and were negative for CD45 and CD34, consistent with other ECFC phenotypes. PECFCs were capable of 28.6 ± 6.0 population doublings before reaching senescence (vs. 47.4 ± 3.2 for CBECFCs, p < 0.05, n = 4). In single cell assays, 46.5 ± 1.2% underwent at least one division (vs. 51.0 ± 1.8% of CBECFCs, p = 0.07, n = 6), and of those dividing PECFCs, 71.8 ± 0.9% gave rise to colonies of >500 cells (highly proliferative potential clones) over 14 days (vs. 69.4 ± 0.7% of CBECFCs, p = 0.07, n = 9). PECFCs formed 5.2 ± 0.8 vessels/mm(2) in collagen/fibronectin plugs implanted into non-obese diabetic/severe combined immunodeficient (NOD/SCID) mice, whereas CBECFCs formed only 1.7 ± 1.0 vessels/mm(2) (p < 0.05, n = 4). This study demonstrates that circulating CBECFCs and resident PECFCs are identical phenotypically and contain equivalent quantities of high proliferative potential clones. However, PECFCs formed significantly more blood vessels in vivo than CBECFCs, indicating that differences in vasculogenic potential between circulating and resident ECFCs exist.

Autologous bone marrow mononuclear cell therapy is safe and promotes amputation-free survival in patients with critical limb ischemia.

OBJECTIVE: The purpose of this Phase I open label nonrandomized trial was to assess the safety and efficacy of autologous bone marrow mononuclear cell (ABMNC) therapy in promoting amputation-free survival (AFS) in patients with critical limb ischemia (CLI). METHODS: Between September 2005 and March 2009, 29 patients (30 limbs), with a median age of 66 years (range, 23-84 years; 14 male, 15 female) with CLI were enrolled. Twenty-one limbs presented with rest pain (RP), six with RP and ulceration, and three with ulcer only. All patients were not candidates for surgical bypass due to absence of a patent artery below the knee and/or endovascular approaches to improving perfusion was not possible as determined by an independent vascular surgeon. Patients were treated with an average dose of 1.7 ± 0.7 × 10(9) ABMNC injected intramuscularly in the index limb distal to the anterior tibial tuberosity. The primary safety end point was accumulation of serious adverse events, and the primary efficacy end point was AFS at 1 year. Secondary end points at 12 weeks posttreatment were changes in first toe pressure (FTP), toe-brachial index (TBI), ankle-brachial index (ABI), and transcutaneous oxygen measurements (TcPO(2)). Perfusion of the index limb was measured with positron emission tomography-computed tomography (PET-CT) with intra-arterial infusion of H(2)O(15). RP, using a 10-cm visual analogue scale, quality of life using the VascuQuol questionnaire, and ulcer healing were assessed at each follow-up interval. Subpopulations of endothelial progenitor cells were quantified prior to ABMNC administration using immunocytochemistry and fluorescent-activated cell sorting. RESULTS: There were two serious adverse events; however, there were no procedure-related deaths. Amputation-free survival at 1 year was 86.3%. There was a significant increase in FTP (10.2 ± 6.2 mm Hg; P = .02) and TBI (0.10 ± 0.05;P = .02) and a trend in improvement in ABI (0.08 ± 0.04; P = .73). Perfusion index by PET-CT H(2)O(15) increased by 19.3 ± 3.1, and RP decreased significantly by 2.2 ± 0.6 cm (P = .02). The VascuQol questionnaire demonstrated significant improvement in quality of life, and three of nine ulcers (33%) healed completely. KDR(+) but not CD34(+) or CD133(+) subpopulations of ABMNC were associated with improvement in limb perfusion. CONCLUSION: This Phase I study has demonstrated safety, and the AFS rates suggest efficacy of ABMNC in promoting limb salvage in "no option" CLI. Based on these results, we plan to test the concept that ABMNCs improve AFS at 1 year in a Phase III randomized, double-blinded, multicenter trial.

Material characterization of porcine lenticular soluble proteins.

The soluble proteins present in the ocular lens impart important optical and dynamic mechanical properties on the lens. The short-range order of crystallin proteins grants transparency to a very concentrated protein solution. This unique protein system directly enables proper visual function of the eye. These proteins were investigated in steady and oscillatory shear. Steady shear data were fitted with a modified Herschel-Bulkley yield stress model that allows for a Newtonian plateau at low shear rates. The Cox-Merz rule was used in conjunction with large amplitude oscillatory shear to give insight into the degradation of the fluid structure with increasing strain. The shear thinning viscoelastic behavior of these proteins gives rise to beneficial mechanical properties and results from the same short-range order granting optical transparency.

Solution NMR structure of the junction between tropomyosin molecules: implications for actin binding and regulation.

Tropomyosin is a coiled-coil protein that binds head-to-tail along the length of actin filaments in eukaryotic cells, stabilizing them and providing protection from severing proteins. Tropomyosin cooperatively regulates actin's interaction with myosin and mediates the Ca2+ -dependent regulation of contraction by troponin in striated muscles. The N-terminal and C-terminal ends are critical functional determinants that form an "overlap complex". Here we report the solution NMR structure of an overlap complex formed of model peptides. In the complex, the chains of the C-terminal coiled coil spread apart to allow insertion of 11 residues of the N-terminal coiled coil into the resulting cleft. The plane of the N-terminal coiled coil is rotated 90 degrees relative to the plane of the C terminus. A consequence of the geometry is that the orientation of postulated periodic actin binding sites on the coiled-coil surface is retained from one molecule to the next along the actin filament when the overlap complex is modeled into the X-ray structure of tropomyosin determined at 7 Angstroms. Nuclear relaxation NMR data reveal flexibility of the junction, which may function to optimize binding along the helical actin filament and to allow mobility of tropomyosin on the filament surface as it switches between regulatory states.

Tropomodulin binds two tropomyosins: a novel model for actin filament capping.

Tropomodulin, a tropomyosin-binding protein, caps the slow-growing (pointed) end of the actin filament regulating its dynamics. Tropomodulin, therefore, is important for determining cell morphology, cell movement, and muscle contraction. For the first time we show that one tropomodulin molecule simultaneously binds two tropomyosin molecules in a cooperative manner. On the basis of the tropomodulin solution structure and predicted secondary structure, we introduced a series of point mutations in regions important for tropomyosin binding and actin capping. Capping activity of these mutants was assayed by measuring actin polymerization using pyrene fluorescence. Using direct methods (circular dichroism and native gel electrophoresis) for detecting tropomodulin/tropomyosin binding, we localized the second tropomyosin-binding site to residues 109-144. Despite previous reports that the second binding site is for erythrocyte tropomyosin only, we found that both short nonmuscle and long muscle alpha-tropomyosins bind there as well, though with different affinities. We propose a model for actin capping where one tropomodulin molecule can bind to two tropomyosin molecules at the pointed end.

Structural requirements of tropomodulin for tropomyosin binding and actin filament capping.

Regulation of actin filament dynamics underlies many cellular functions. Tropomodulin together with tropomyosin can cap the pointed, slowly polymerizing, filament end, inhibiting addition or loss of actin monomers. Tropomodulin has an unstructured N-terminal region that binds tropomyosin and a folded C-terminal domain with six leucine-rich repeats. Of tropomodulin 1's 359 amino acids, an N-terminal fragment (Tmod1(1)(-)(92)) suffices for in vitro function, even though the C-terminal domain can weakly cap filaments independent of tropomyosin. Except for one short alpha-helix with coiled coil propensity (residues 24-35), the Tmod1(1)(-)(92) solution structure shows that the fragment is disordered and highly flexible. On the basis of the solution structure and predicted secondary structure, we have introduced a series of mutations to determine the structural requirements for tropomyosin binding (using native gels and CD) and filament capping (by measuring actin polymerization using pyrene fluorescence). Tmod1(1)(-)(92) fragments with mutations of an interface hydrophobic residue, L27G and L27E, designed to destroy the alpha-helix or coiled coil propensity, lost binding ability to tropomyosin but retained partial capping function in the presence of tropomyosin. Replacement of a flexible region with alpha-helical residues (residues 59-61 mutated to Ala) had no effect on tropomyosin binding but inhibited the capping function. A mutation in a region predicted to be an amphipathic helix (residues 65-75), L71D, destroyed the capping function. The results suggest that molecular flexibility and binding to actin via an amphipathic helix are both required for tropomyosin-dependent capping of the pointed end of the actin filament.