Depopulated vena caval homograft: a new venous conduit

Acellular blood vessels combined human hair follicle mesenchymal stem cells for engineering of functional arterial grafts

Tissue-engineered vessels offer options for autologous vascular grafts in cardiovascular repair and regeneration. The experiments aimed to construct functional arterial grafts by combining human hair follicle mesenchymal stem cells (HF-MSCs) with acellular umbilical arteries. We isolated mesenchymal stem cells from human hair follicles. Under appropriate culture conditions, these cells displayed CD44, CD90 and CD105, and exhibited the potential for differentiation to adipocytes, osteoblasts and chondrocytes. Very promisingly, HF-MSCs expressed the vascular smooth muscle specific markers in the presence of transforming growth factor-β. We created acellular arterial scaffolds by digesting human umbilical arteries with trypsin and sodium dodecyl sulfate. These acellular arterial scaffolds retained major components of the extracellular matrix. The mechanical properties of these acellular arterial scaffolds were very similar to those of native blood vessels. We then seeded HF-MSCs into acellular arterial scaffolds and found that they still expressed vascular smooth muscle specific markers. The arterial grafts derived from HF-MSCs demonstrated vasoreactivity in response to humoral constrictors. We constructed arterial grafts that are very close to native blood vessels in their structures and physiological functions. These properties suggest that these arterial grafts could be used as small diameter arterial grafts for cardiovascular repair and regeneration.

Tissue-engineered vascular grafts for use in the treatment of congenital heart disease: from the bench to the clinic and back again

Since the first tissue-engineered vascular graft (TEVG) was implanted in a child over a decade ago, growth in the field of vascular tissue engineering has been driven by clinical demand for improved vascular prostheses with performance and durability similar to an autologous blood vessel. Great strides were made in pediatric congenital heart surgery using the classical tissue engineering paradigm, and cell seeding of scaffolds in vitro remained the cornerstone of neotissue formation. Our second-generation bone marrow cell-seeded TEVG diverged from tissue engineering dogma with a design that induces the recipient to regenerate vascular tissue in situ. New insights suggest that neovessel development is guided by cell signals derived from both seeded cells and host inflammatory cells that infiltrate the graft. The identification of these signals and the regulatory interactions that influence cell migration, phenotype and extracellular matrix deposition during TEVG remodeling are yielding a next-generation TEVG engineered to guide neotissue regeneration without the use of seeded cells. These developments represent steady progress towards our goal of an off-the-shelf tissue-engineered vascular conduit for pediatric congenital heart surgery.

Banked depopulated vena caval homograft: a new strategy to restore caval continuity

This study reports one case of primary inferior vena cava (IVC) leiomyosarcoma. A 67-year-old woman was referred to the authors' clinic for evaluation. She presented complaining of epigastric and right upper abdominal quadrant pain. Contrast-enhanced abdominal computed tomography scan revealed a 5.2 × 6.4 cm heterogeneously enhancing mass involving the anteromedial aspect of the IVC, below the renal vein (segment I), deforming the duodenum. There was a partial intraluminal extension in the IVC. Laparotomic resection was performed, with total en bloc excision of the lower IVC tumor. The caval continuity was restored with concomitant interposition of a banked depopulated vena cava homograft. Histological findings showed leiomyosarcoma originating from IVC. The postoperative course was uneventful: Neither recurrence nor metastasis was evident at 4 years postsurgery.

Novel utilization of serum in tissue decellularization

Decellularization of native tissues is a promising technique with numerous applications in tissue engineering and regenerative medicine. However, there are various limitations of currently available decellularization methods, such as alteration of extracellular matrix mechanics and restricted use on certain tissues. This study was conducted to explore the effect of serum on the decellularization of various types of tissues. Fetal bovine serum-containing cell culture medium endothelial growth media-2 removed DNA but not cellular beta-actin from human umbilical artery after detergent treatment, without compromising the tissue mechanical strength assessed by burst pressure. In addition, the effect of serum-containing endothelial growth media-2 on DNA removal was replicated in other types of tissues such as tissue-engineered vessels and myocardium. Other types of serum, including human serum, were also shown to remove DNA from detergent-pretreated tissues. In conclusion, we describe a novel utilization of serum that may have broad applications in tissue decellularization.

Development of decellularized human umbilical arteries as small-diameter vascular grafts

OBJECTIVE

Developing a tissue-engineered small-diameter (<6mm) vascular graft for reconstructive surgery has remained a challenge for the past several decades. This study was conducted to develop a decellularized umbilical artery and to evaluate its composition, endothelial cell compatibility, mechanical properties, and in vivo stability for potential use as a small-diameter vascular graft.

METHODS AND RESULTS

Human umbilical arteries were isolated and decellularized by incubation in CHAPS and sodium dodecyl sulfate buffers followed by incubation in endothelial growth media-2. Decellularized umbilical arteries were completely devoid of cellular and nuclear material while retaining the integrity of extracellular collagenous matrix. The mechanical strength of the decellularized umbilical artery as assessed by its burst pressure in vitro showed no significant change from its native form. Decellularized umbilical arteries supported endothelial adherence as indicated by the re-endotheliazation with a monolayer of human umbilical vein endothelial cells. Furthermore, decellularized vessels that were implanted into nude rats as abdominal aorta interposition grafts remained mechanically intact and patent for up to 8 weeks.

CONCLUSION

Decellularized human umbilical arteries preserved the extracellular matrix, supported endothelialization, and retained function in vivo for up to 8 weeks. These properties suggest the potential use of decellularized umbilical arteries as small-diameter vascular grafts.

Aortic root replacement with a novel decellularized cryopreserved aortic homograft: Postoperative immunoreactivity and early results

OBJECTIVE

Novel antigen-reduction SynerGraft technology (CryoLife Inc, Kennesaw, Ga) reduces the cellular components of a cadaver homograft with an enzymatic and washing process, leaving the extracellular matrix intact. We report the immunoreactivity (positive panel reactive antibody assay) and early operative results of the CryoLife SynerGraft aortic valve conduit homograft.

METHODS

Twenty-two patients (age 53 +/- 14 years, range 31-80 years) from April 2002 to July 2003 underwent aortic root replacement with a CryoLife SynerGraft aortic valve conduit homograft (CryoLife Inc, Kennesaw, Ga) for congenital or acquired aortic valve disease, aortic aneurysm with aortic valve disease, or native or prosthetic aortic valve endocarditis. Baseline percentage positive panel reactive antibody results were negative (<10%) for all and were assessed at 1 month, 3 months, and 1-year. Homograft function was evaluated by echocardiography.

RESULTS

Early mortality was 0%. Two late deaths at 1 postoperative year were unrelated to homograft function. At 1 postoperative month, panel reactive antibody results were negative in 20 patients (91%). At 3 months, 19 of 22 patients (86%) had negative results, including 1 with previous positive results. At 1 year, 19 of 20 patients (95%) had negative results, including 2 of the 3 with previous positive results. The mean aortic valve gradients were 12 +/- 8 mm Hg (n = 21) at discharge and 11 +/- 7 mm Hg (n = 18) at 1 year. At a mean follow-up of 30.3 +/- 5.2 months, the mean gradient was 8.8 +/- 6.3 mm Hg.

CONCLUSION

The SynerGraft decellularization technology successfully removed antigens from an aortic valve homograft conduit. Aortic root reconstruction with the CryoLife SynerGraft aortic valve homograft resulted in low transvalvular gradients, similar to those seen with standard cryopreserved homografts. These early results suggest an advancement in homograft technology. The low panel reactive antibody response may enhance durability by eliminating immune complex-mediated reaction against the homograft. The lack of allosensitization in patients who may require organ transplantation in the future is an added benefit.

Congenital heart disease never goes away, even when it has been 'treated': the adult with congenital heart disease

PURPOSE OF REVIEW

As the specialties of pediatrics and pediatric cardiology continue to forge ahead with better diagnoses, medical care, and surgical results, an expanding population of patients with congenital heart disease (CHD) outgrows the pediatric age group, yet does not quite graduate to routine adult cardiology or general medicine. The adult with congenital heart disease (ACHD) faces medical, surgical, and psychosocial issues that are unique to this population and must be addressed as such. This review attempts to discuss and highlight some of the important advances and controversies brought up in the past year, in the care and management of these patients.

RECENT FINDINGS

The past five to 10 years have seen dynamic interest in understanding sequelae of corrected, uncorrected, or palliated congenital heart disease. The search for the ideal surgery, optimal prosthesis, and a smooth transition to adult care continues and is reflected in the vast amount of academic work and publications in this field. Of particular interest, conduit reoperations and single ventricle pathway modifications are still an art and a science in evolution.

SUMMARY

While all are agreed that there is a pressing need to focus on the delivery of care to the adult with congenital heart disease, this essentially requires a clearer understanding of late sequelae of CHD. The sheer heterogeneity of anatomy, age, surgery, and institutional management protocols can make it difficult to develop clear guidelines. This review attempts to give an up-to-date perspective on some of the new findings related to the more common lesions and problems faced in this group.