Early complications of biologic extracellular matrix patch after use for femoral artery repair

Development of heparinized and hepatocyte growth factor-coated acellular scaffolds using porcine carotid arteries

Tissue-engineered blood vessel substitutes have been developed due to the lack of suitable small-diameter vascular grafts. Xenogeneic extracellular matrix (ECM) scaffolds have the potential to provide an ideal source for off-the-shelf vascular grafts. In this study, porcine carotid arteries were used to develop ECM scaffolds by decellularization and coating with heparin and hepatocyte growth factor (HGF). After decellularization, cellular and nucleic materials were successfully removed with preservation of the main compositions (collagen, elastin, and basement membrane) of the native ECM. The ultimate tensile strength, suture strength, and burst pressure were significantly increased after cross-linking. Pore size distribution analysis revealed a porous structure within ECM scaffolds with a high distribution of pores larger than 10 μm. Heparinized scaffolds exhibited sustained release of heparin in vitro and showed potent anticoagulant activity by prolonging activated partial thromboplastin time. The scaffolds showed an enhanced HGF binding capacity as well as a constant release of HGF as a result of heparin modification. When implanted subcutaneously in rats, the modified scaffolds revealed good biocompatibility with enzyme degradation resistance, mitigated immune response, and anti-calcification. In conclusion, heparinized and HGF-coated acellular porcine carotid arteries may be a promising biological scaffold for tissue-engineered vascular grafts.

Six-year outcomes of a phase II study of human-tissue engineered blood vessels for peripheral arterial bypass

Objective

The human acellular vessel (HAV) was evaluated for surgical bypass in a phase II study. The primary results at 24 months after implantation have been reported, and the patients will be evaluated for ≤10 years.

Methods

In the present report, we have described the 6-year results of a prospective, open-label, single-treatment arm, multicenter study. Patients with advanced peripheral artery disease (PAD) requiring above-the-knee femoropopliteal bypass surgery without available autologous graft options had undergone implantation with the HAV, a bioengineered human tissue replacement blood vessel. The patients who completed the 24-month primary portion of the study will be evaluated for ≤10 years after implantation. The present mid-term analysis was performed at the 6-year milestone (72 months) for patients followed up for 24 to 72 months.

Results

HAVs were implanted in 20 patients at three sites in Poland. Seven patients had discontinued the study before completing the 2-year portion of the study: four after graft occlusion had occurred and three who had died of causes deemed unrelated to the conduit, with the HAV reported as functional at their last visit. The primary results at 24 months showed primary, primary assisted, and secondary patency rates of 58%, 58%, and 74%, respectively. One vessel had developed a pseudoaneurysm deemed possibly iatrogenic; no other signs of structural failure were reported. No rejections or infections of the HAV occurred, and no patient had required amputation of the implanted limb. Of the 20 patients, 13 had completed the primary portion of the study; however, 1 patient had died shortly after 24 months. Of the remaining 12 patients, 3 died of causes unrelated to the HAV. One patient had required thrombectomy twice, with secondary patency achieved. No other interventions were recorded between 24 and 72 months. At 72 months, five patients had a patent HAV, including four patients with primary patency. For the entire study population from day 1 to month 72, the overall primary, primary assisted, and secondary patency rate estimated using Kaplan-Meier analysis was 44%, 45%, and 60% respectively, with censoring for death. No patient had experienced rejection or infection of the HAV, and no patient had required amputation of the implanted limb.

Conclusions

The infection-resistant, off-the-shelf HAV could provide a durable alternative conduit in the arterial circuit setting to restore the lower extremity blood supply in patients with PAD, with remodeling into the recipient's own vessel over time. The HAV is currently being evaluated in seven clinical trials to treat PAD, vascular trauma, and as a hemodialysis access conduit.

Bioengineering Human Tissues and the Future of Vascular Replacement

Cardiovascular defects, injuries, and degenerative diseases often require surgical intervention and the use of implantable replacement material and conduits. Traditional vascular grafts made of synthetic polymers, animal and cadaveric tissues, or autologous vasculature have been utilized for almost a century with well-characterized outcomes, leaving areas of unmet need for the patients in terms of durability and long-term patency, susceptibility to infection, immunogenicity associated with the risk of rejection, and inflammation and mechanical failure. Research to address these limitations is exploring avenues as diverse as gene therapy, cell therapy, cell reprogramming, and bioengineering of human tissue and replacement organs. Tissue-engineered vascular conduits, either with viable autologous cells or decellularized, are the forefront of technology in cardiovascular reconstruction and offer many benefits over traditional graft materials, particularly in the potential for the implanted material to be adopted and remodeled into host tissue and thus offer safer, more durable performance. This review discusses the key advances and future directions in the field of surgical vascular repair, replacement, and reconstruction, with a focus on the challenges and expected benefits of bioengineering human tissues and blood vessels.

Surgical Reconstruction of a Left Ventricular Aneurysm Using an Extracellular Matrix Patch

The left ventricular aneurysm is a pathological condition defined as an akinetic or dyskinetic area of the left ventricle (LV) wall associated with reduced ejection fraction. The most common surgical technique to reconstruct a left ventricular aneurysm is endoventricular patch plasty (Dor procedure). In this case, endoventricular reconstruction of the left ventricular aneurysm using a double-layer extracellular matrix was performed.

Two new applications in the study of angiogenesis the CAM assay: Acellular scaffolds and organoids

The chick embryo chorioallantoic membrane (CAM) is a rich vascularized extraembryonic membrane that is commonly used as an in vivo experimental model to study molecules with angiogenic and anti-angiogenic activity, tumor growth and metastasis. Among other applications of the CAM assay, more recently this assay has been used for the study of acellular scaffolds and of organoids, and of their angiogenic capacity. The aim of this review article is to summarize the literature data concerning these two new applications of the CAM assay and to underline the advantages of this assay.

Extracellular Matrix Patches for Endarterectomy Repair

Patch repair is the preferred method for arteriotomy closure following femoral or carotid endarterectomy. Choosing among available patch options remains a clinical challenge, as current evidence suggests roughly comparable outcomes between autologous grafts and synthetic and biologic materials. Biologic patches have potential advantages over other materials, including reduced risk for infection, mitigation of an excessive foreign body response, and the potential to remodel into healthy, vascularized tissue. Here we review the use of decellularized extracellular matrix (ECM) for cardiovascular applications, particularly endarterectomy repair, and the capacity of these materials to remodel into native, site-appropriate tissues. Also presented are data from two post-market observational studies of patients undergoing iliofemoral and carotid endarterectomy patch repair as well as one histologic case report in a challenging iliofemoral endarterectomy repair, all with the use of small intestine submucosa (SIS)-ECM. In alignment with previously reported studies, high patency was maintained, and adverse event rates were comparable to previously reported rates of patch angioplasty. Histologic analysis from one case identified constructive remodeling of the SIS-ECM, consistent with the histologic characteristics of the endarterectomized vessel. These clinical and histologic results align with the biologic potential described in the academic ECM literature. To our knowledge, this is the first histologic demonstration of SIS-ECM remodeling into site-appropriate vascular tissues following endarterectomy. Together, these findings support the safety and efficacy of SIS-ECM for patch repair of femoral and carotid arteriotomy.

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.

Multimodality Imaging in the Evaluation of Ascending Aortic Pseudoaneurysms to Guide Complex Surgical Management

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Treatment of an AAP is surgical.

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The CorMatrix patch can lead to degradation and pseudoaneurysm formation.

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Use of multimodality imaging is key to evaluate, diagnose, and guide operation.

Bioengineered human blood vessels

Since the advent of the vascular anastomosis by Alexis Carrel in the early 20th century, the repair and replacement of blood vessels have been key to treating acute injuries, as well as chronic atherosclerotic disease. Arteries serve diverse mechanical and biological functions, such as conducting blood to tissues, interacting with the coagulation system, and modulating resistance to blood flow. Early approaches for arterial replacement used artificial materials, which were supplanted by polymer fabrics in recent decades. With recent advances in the engineering of connective tissues, including arteries, we are on the cusp of seeing engineered human arteries become mainstays of surgical therapy for vascular disease. Progress in our understanding of physiology, cell biology, and biomanufacturing over the past several decades has made these advances possible.

Evaluation of Explanted CorMatrix Tyke Extracardiac Patches in Infants With Congenital Heart Disease

BACKGROUND

Animal data demonstrate that intracardiac patches of decellularized porcine small intestine submucosa (CorMatrix; CorMatrix Cardiovascular, Atlanta, GA) become repopulated with native cells, suggesting the possibility of a substrate for regenerative tissue in humans. Although human studies have not demonstrated this regenerative property with intracardiac patches, it is possible that other environments may better promote native cell repopulation. We report a prospective series of explanted CorMatrix extracardiac patches placed in infants with congenital heart disease.

METHODS

CorMatrix Tyke patches were used in pulmonary artery patch closure during the Norwood procedure. The patch material was explanted as part of the hemi-Fontan procedure. Specimens were analyzed with the use of hematoxylin and eosin, Movat pentachrome, and trichrome stains.

RESULTS

Of the 11 implantations, 9 specimens were explanted. One patient did not survive to hemi-Fontan procedure. One patient's patch was removed, but not analyzed. Acellular material, chronic inflammation, fibrosis, and foreign body giant cell reaction was seen in all explanted patches. No explanted CorMatrix Tyke material demonstrated evidence of ingrowth of native endothelial tissue at a median of 4.9 months in vivo.

CONCLUSIONS

CorMatrix Tyke patch material, placed as a pulmonary artery patch in an extracardiac position, remained pliable and mostly free of calcification. However, these patches did not show evidence of native endothelial tissue at a median of 4.9 months in vivo.

Bioengineered human acellular vessels recellularize and evolve into living blood vessels after human implantation

Traditional vascular grafts constructed from synthetic polymers or cadaveric human or animal tissues support the clinical need for readily available blood vessels, but often come with associated risks. Histopathological evaluation of these materials has shown adverse host cellular reactions and/or mechanical degradation due to insufficient or inappropriate matrix remodeling. We developed an investigational bioengineered human acellular vessel (HAV), which is currently being studied as a hemodialysis conduit in patients with end-stage renal disease. In rare cases, small samples of HAV were recovered during routine surgical interventions and used to examine the temporal and spatial pattern of the host cell response to the HAV after implantation, from 16 to 200 weeks. We observed a substantial influx of alpha smooth muscle actin (αSMA)-expressing cells into the HAV that progressively matured and circumferentially aligned in the HAV wall. These cells were supported by microvasculature initially formed by CD34⁺/CD31⁺ cells in the neoadventitia and later maintained by CD34^-/CD31⁺ endothelial cells in the media and lumen of the HAV. Nestin⁺ progenitor cells differentiated into either αSMA⁺ or CD31⁺ cells and may contribute to early recellularization and self-repair of the HAV. A mesenchymal stem cell-like CD90⁺ progenitor cell population increased in number with duration of implantation. Our results suggest that host myogenic, endothelial, and progenitor cell repopulation of HAVs transforms these previously acellular vessels into functional multilayered living tissues that maintain blood transport and exhibit self-healing after cannulation injury, effectively rendering these vessels like the patient's own blood vessel.

State-of-the-Art Strategies for the Vascularization of Three-Dimensional Engineered Organs

Engineering three-dimensional (3D) implantable tissue constructs is a promising strategy for replacing damaged or diseased tissues and organs with functional replacements. However, the efficient vascularization of new 3D organs is a major scientific and technical challenge since large tissue constructs or organs require a constant blood supply to survive in vivo. Current approaches to solving this problem generally fall into the following three major categories: (a) cell-based, (b) angiogenic factor-based, and (c) scaffold-based. In this review, we summarize state-of-the-art technologies that are used to develop complex, stable, and functional vasculature for engineered 3D tissue constructs and organs; additionally, we have suggested directions for future research.

Evaluation of a hybrid small caliber vascular graft in a rabbit model

OBJECTIVE

A hybrid small-caliber artificial vascular graft based on bilayer porcine small intestinal submucosa (SIS) with curdlan and dipyridamole mixture film serving as the so-called sandwich filler was developed for biological performance evaluation. We evaluated the performance of the graft and filler.

METHODS

SIS was coated with heparin by 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide. Curdlan acted as the carrier of dipyridamole. Three types of graft tubes (2 mm internal diameter and 20 mm in length) were manufactured: bilayer SIS with 10% curdlan + 10% dipyridamole mixture film (SCD), bilayer SIS with 10% curdlan film (SC), and monolayer SIS (S). The remodeling characteristics of the grafts were evaluated by implanting them as bypass in rabbit carotid arteries for 2 and 3 months. Each group contained 16 rabbits, and 16 nonsurgical rabbits served as the control group.

RESULTS

Eight rabbits of each group, including the graft occluded group, were killed at 2 months and the others were killed at 3 months. Follow-up showed that all 8 grafts in SCD group were patent at 2 months. Six of 16 grafts in the SC group and 5 of 16 grafts in the S group were occluded at 2 months. One of 8 SCD grafts were occluded at 3 months and the patent showed a confluent endothelium without intimal hyperplasia. The neointima layer was composed of circumferentially aligned vascular smooth muscle cells. At 3 months, SC and S group grafts showed incomplete endothelialization and varying degrees of mural thrombus, accompanied by occlusion in the SC group (3 of 8) and S group (2 of 8).

CONCLUSIONS

The novel hybrid small caliber artificial vascular graft exhibited an improvement in revascularization resulting in high patency rate.

Successful decellularization of thick-walled tissue: Highlighting pitfalls and the need for a multifactorial approach

INTRODUCTION:

Decellularization of thick tissue is challenging and varying. Therefore, we tried to establish a multifactorial approach for reliable aortic wall decellularization.

METHODS:

Porcine aortic walls were decellularized according to different procedures. Decellularization was performed for 24 (G1), 48 (G2), and 72 h (G3) with a solution of 0.5% desoxycholate and 0.5% dodecyl sulfate. The procedure was characterized using intermittent washing steps, the inclusion of sonication as well as DNase and α-galactosidase treatment. The decellularization efficiency was measured by the evaluation of 4',6-diamidino-2-phenylindole and hematoxylin and eosin staining and quantitative DNA assays. Pentachrome and picrosirius red staining, scanning electron microscopy as well as glycosaminoglycan assays were performed to evaluate the effect of the procedure on the extracellular matrix.

RESULTS:

4',6-Diamidino-2-phenylindole and hematoxylin and eosin staining revealed a large amount of remaining nuclei in all groups. However, consecutive DNase treatment had a significant effect. While the remaining DNA was detected in some samples of G1 and G2, samples of G3 were fully decellularized. Glycosaminoglycan content was significantly reduced to 50% after 24 h (G1) but remained constant for G2 and G3. Picrosirius red staining revealed an intact and stable collagen network without any visible defects. Pentachrome staining substantiated these results. Nonetheless, the fiber network remains intact, which could be confirmed by reflection electron microscopy analysis.

CONCLUSION:

In this study, we developed a procedure that grants successful decellularization of porcine aortic wall while maintaining the fibrous microstructure. We highlighted the significant effect of DNase and α-galactosidase treatment. In addition, we could show the need for a multifactorial treatment and comprehensive evaluation protocols for thick tissue decellularization.

Common femoral artery endarterectomy in the age of endovascular therapy

OBJECTIVES

Common femoral artery endarterectomy (CFE) is the standard treatment for common femoral artery occlusive disease. We aim to assess the medium term outcomes of CFE with or without further concomitant procedures.

DESIGN

A retrospective observational study.

METHODS

All patients who underwent either isolated CFE (ICFE), CFE with angioplasty for occlusive arterial disease (CFEA) or concomitant CFE with endovascular aortic aneurysm repair (CFEE) were included. Patient demographics follow up, clinical improvement, types of CFE closure, patency rates, and survival-free amputation were noted.

RESULTS

From 2002 to 2015, 1512 patients were referred with a diagnosis of critical limb ischemia. Of those, 1134 required revascularization. Sixty-one patients underwent 66 CFE. Ten limbs underwent an ICFE, 35 had CFEA, and 21 underwent CFEE. Demographics were comparable in all groups. Twenty-seven were closed primarily, while 39 required patch closure (12 venous, 8 Dacron, 19 biological). Technical success was 100% in ICFEs, 94% in CFEA, and 100% for CFEE ( p = 0.274). Immediate clinical success was 100% in both CFE and CFEE, but was 85.7% in CFEA ( p = 0.035). Immediate hemodynamic success was similar in all three groups ( p = 0.73). Sustained hemodynamic success was 30% in ICFE, 54.3% in CFEA, and 23.8% in CFEE ( p = 0.056). At two years, the primary patency was 90% in ICFE, 74.3% in CFEA, and 100% in CFEE ( p = 0.049). Primary-assisted patency was 90% in ICFE, 82.9% in CFEA, and 100% in CFEE ( p = 0.17). Secondary patency was 90% in ICFE, 94.3% in CFEA, and 100% in CFEE ( p = 0.409). Re-intervention was required in 26.9% of primary closures, versus 12.8% with patch closures ( p = 0.279). Amputation-free survival was 100% in ICFE, 80% in CFEA, and 100% in CFEE ( p = 0.056).

CONCLUSION

CFE is a reliable and dependable procedure, even in the absence of good distal runoff.

Is Decellularized Porcine Small Intestine Sub-mucosa Patch Suitable for Aortic Arch Repair?

Introduction: We reviewed our experience with decellularized porcine small intestine sub-mucosa (DPSIS) patch, recently introduced for congenital heart defects. Materials and Methods: Between 10/2011 and 04/2016 a DPSIS patch was used in 51 patients, median age 1.1 months (5 days to 14.5 years), for aortic arch reconstruction (45/51 = 88.2%) or aortic coarctation repair (6/51 = 11.8%). All medical records were retrospectively reviewed, with primary endpoints interventional procedure (balloon dilatation) or surgery (DPSIS patch replacement) due to patch-related complications. Results: In a median follow-up time of 1.5 ± 1.1 years (0.6-2.3years) in 13/51 patients (25.5%) a re-intervention, percutaneous interventional procedure (5/51 = 9.8%) or re-operation (8/51 = 15.7%) was required because of obstruction in the correspondence of the DPSIS patch used to enlarge the aortic arch/isthmus, with median max velocity flow at Doppler interrogation of 4.0 ± 0.51 m/s. Two patients required surgery after failed interventional cardiology. The mean interval between DPSIS patch implantation and re-intervention (percutaneous procedure or re-operation) was 6 months (1-17 months). While there were 3 hospital deaths (3/51 = 5.9%) not related to the patch implantation, no early or late mortality occurred for the subsequent procedure required for DPSIS patch interventional cardiology or surgery. The median max velocity flow at Doppler interrogation through the aortic arch/isthmus for the patients who did not require interventional procedure or surgery was 1.7 ± 0.57 m/s. Conclusions: High incidence of re-interventions with DPSIS patch for aortic arch and/or coarctation forced us to use alternative materials (homografts and decellularized gluteraldehyde preserved bovine pericardial matrix).