Oversized Conduits Predict Stenosis in Tissue Engineered Vascular Grafts.

Tissue-engineered vascular grafts (TEVGs) offer promising advancements in treating congenital heart disease by enabling the creation of autologous tissue for complex cardiac repairs. Our approach involves implanting biodegradable scaffolds seeded with autologous cells that remodel into functional neovessels. To understand better the factors guiding neovessel formation, we evaluated 50 ovine thoracic TEVGs using angiography at 1 and 6 weeks postimplantation.

Regional Differences in Vascular Graft Degradation and Regeneration Contribute to Dilation.

Severe coronary artery disease is often treated with a coronary artery bypass graft using an autologous blood vessel. When this is not available, a commercially available synthetic graft can be used as an alternative but is associated with high failure rates and complications. Therefore, the research focus has shifted toward the development of biodegradable, regenerative vascular grafts that can convert into neoarteries.

Tissue engineered vascular grafts are resistant to the formation of dystrophic calcification.

Advancements in congenital heart surgery have heightened the importance of durable biomaterials for adult survivors. Dystrophic calcification poses a significant risk to the long-term viability of prosthetic biomaterials in these procedures. Herein, we describe the natural history of calcification in the most frequently used vascular conduits, expanded polytetrafluoroethylene grafts.

Reducing Opioid Overprescribing through Procedure-specific Prescribing Guidelines.

Unlabelled: Despite advances in opioid-sparing pain management, postdischarge opioid overprescribing in plastic surgery remains an issue. Procedure-specific prescribing protocols have been implemented successfully in other surgical specialties but not broadly in plastic surgery. This study examined the efficacy of procedure-specific prescribing guidelines for reducing postdischarge opioid overprescribing.

A Personalized Opioid Prescription Model for Predicting Postoperative Discharge Opioid Needs.

Background: Opioid overprescribing after surgery is common. There is currently no universal predictive tool available to accurately anticipate postdischarge opioid need in a patient-specific manner. This study examined the efficacy of a patient-specific opioid prescribing framework for estimating postdischarge opioid consumption.

Tamoxifen reduces silicone implant capsule formation in a mouse model.

Capsular contracture as a result of the foreign body response (FBR) is a common issue after implant-based breast reconstruction, affecting up to 20% of patients. New evidence suggests that tamoxifen may mitigate the FBR. C57BL/6 female mice were treated with daily tamoxifen or control injections and implanted with bilateral silicone implants in the submammary glandular plane.

Rapid Regeneration of a Neoartery with Elastic Lamellae.

Native arteries contain a distinctive intima-media composed of organized elastin and an adventitia containing mature collagen fibrils. In contrast, implanted biodegradable small-diameter vascular grafts do not present spatially regenerated, organized elastin. The elastin-containing structures within the intima-media region encompass the elastic lamellae (EL) and internal elastic lamina (IEL) and are crucial for normal arterial function.

Tissue engineered vascular grafts transform into autologous neovessels capable of native function and growth.

Background: Tissue-engineered vascular grafts (TEVGs) have the potential to advance the surgical management of infants and children requiring congenital heart surgery by creating functional vascular conduits with growth capacity.

Methods: Herein, we used an integrative computational-experimental approach to elucidate the natural history of neovessel formation in a large animal preclinical model; combining an in vitro accelerated degradation study with mechanical testing, large animal implantation studies with in vivo imaging and histology, and data-informed computational growth and remodeling models.

Results: Our findings demonstrate that the structural integrity of the polymeric scaffold is lost over the first 26 weeks in vivo, while polymeric fragments persist for up to 52 weeks.

The lysosomal trafficking regulator is necessary for normal wound healing.

Non-healing wounds are a major threat to public health throughout the United States. Tissue healing is complex multifactorial process that requires synchronicity of several cell types. Endolysosomal trafficking, which contributes to various cell functions from protein degradation to plasma membrane repair, is an understudied process in the context of wound healing.

Hemodynamic performance of tissue-engineered vascular grafts in Fontan patients.

In the field of congenital heart surgery, tissue-engineered vascular grafts (TEVGs) are a promising alternative to traditionally used synthetic grafts. Our group has pioneered the use of TEVGs as a conduit between the inferior vena cava and the pulmonary arteries in the Fontan operation. The natural history of graft remodeling and its effect on hemodynamic performance has not been well characterized.

Identification of a population of peripheral sensory neurons that regulates blood pressure.

The vasculature is innervated by a network of peripheral afferents that sense and regulate blood flow. Here, we describe a system of non-peptidergic sensory neurons with cell bodies in the spinal ganglia that regulate vascular tone in the distal arteries. We identify a population of mechanosensitive neurons, marked by tropomyosin receptor kinase C (TrkC) and tyrosine hydroxylase in the dorsal root ganglia, which projects to blood vessels.

Sex and Tamoxifen confound murine experimental studies in cardiovascular tissue engineering.

Tissue engineered vascular grafts hold promise for the creation of functional blood vessels from biodegradable scaffolds. Because the precise mechanisms regulating this process are still under investigation, inducible genetic mouse models are an important and widely used research tool. However, here we describe the importance of challenging the baseline assumption that tamoxifen is inert when used as a small molecule inducer in the context of cardiovascular tissue engineering.

Tissue engineering: Relevance to neonatal congenital heart disease.

Congenital heart disease (CHD) represents a large clinical burden, representing the most common cause of birth defect-related death in the newborn. The mainstay of treatment for CHD remains palliative surgery using prosthetic vascular grafts and valves. These devices have limited effectiveness in pediatric patients due to thrombosis, infection, limited endothelialization, and a lack of growth potential.

Tissue Engineered Vascular Graft Recipient Interleukin 10 Status Is Critical for Preventing Thrombosis.

Tissue engineered vascular grafts (TEVGs) are a promising technology, but are hindered by occlusion. Seeding with bone-marrow derived mononuclear cells (BM-MNCs) mitigates occlusion, yet the precise mechanism remains unclear. Seeded cells disappear quickly and potentially mediate an anti-inflammatory effect through paracrine signaling.

Effects of Braiding Parameters on Tissue Engineered Vascular Graft Development.

Tissue engineered vascular grafts (TEVGs) using scaffolds fabricated from braided poly(glycolic acid) (PGA) fibers coated with poly(glycerol sebacate) (PGS) are developed. The approach relies on in vivo tissue engineering by which neotissue forms solely within the body after a scaffold has been implanted. Herein, the impact of altering scaffold braid design and scaffold coating on neotissue formation is investigated.

Development of Tissue Engineered Heart Valves for Percutaneous Transcatheter Delivery in a Fetal Ovine Model.

This multidisciplinary work shows the feasibility of replacing the fetal pulmonary valve with a percutaneous, transcatheter, fully biodegradable tissue-engineered heart valve (TEHV), which was studied in vitro through accelerated degradation, mechanical, and hemodynamic testing and in vivo by implantation into a fetal lamb. The TEHV exhibited only trivial stenosis and regurgitation in vitro and no stenosis in vivo by echocardiogram. Following implantation, the fetus matured and was delivered at term.

Electrospun Tissue-Engineered Arterial Graft Thickness Affects Long-Term Composition and Mechanics.

Wall stress is often lower in tissue-engineered constructs than in comparable native tissues due to the use of stiff polymeric materials having thicker walls. In this work, we sought to design a murine arterial graft having a more favorable local mechanical environment for the infiltrating cells; we used electrospinning to enclose a compliant inner core of poly(glycerol sebacate) with a stiffer sheath of poly(caprolactone) to reduce the potential for rupture. Two scaffolds were designed that differed in the thickness of the core as previous computational simulations found that circumferential wall stresses could be increased in the core toward native values by increasing the ratio of the core:sheath.

Spontaneous reversal of stenosis in tissue-engineered vascular grafts.

We developed a tissue-engineered vascular graft (TEVG) for use in children and present results of a U.S. Food and Drug Administration (FDA)-approved clinical trial evaluating this graft in patients with single-ventricle cardiac anomalies.

Fetal Transcatheter Trileaflet Heart Valve Hemodynamics: Implications of Scaling on Valve Mechanics and Turbulence.

The scarcity of data available on the best approach for pulmonary fetal valve replacement or implantation necessitate an investigation on whether practices using adult transcatheter valves could be translated to fetal applications. The objective of this study is to evaluate the hemodynamic characteristics and the turbulent properties of a fetal sized trileaflet transcatheter pulmonary valve in comparison with an adult balloon-expandable valve in order to assess the possibility of designing valves for fetal applications using dynamic similarity. A 6 mm fetal trileaflet valve and a 26 mm SAPIEN 3 valve were assessed in a pulse duplicator.

Degradation and evaluation of polycaprolactone, poly(ε-caprolactone-co-L-lactide), and poly-L-lactic acid as scaffold sealant polymers for murine tissue-engineered vascular grafts.

This study evaluates scaffold degradation and neotissue formation as a function of sealant polymer composition in tissue-engineered vascular grafts (TEVGs). Scaffolds fabricated from polyglycolic acid core and sealant composed of polycaprolactone (PCL), poly-L-lactic-acid (PLLA) or 50:50 copolymer poly(ε-caprolactone-co-L-lactide) (PCLA) were analyzed using accelerated degradation and scanning electron microscopy, and following implantation in a murine inferior vena cava interposition model. and characterization revealed statistically greater degradation of PCLA compared with both PCL and PLLA scaffolds, with similar neotissue formation across all groups.

Tissue-Engineered Heart Valves: A Call for Mechanistic Studies.

Heart valve disease carries a substantial risk of morbidity and mortality. Outcomes are significantly improved by valve replacement, but currently available mechanical and biological replacement valves are associated with complications of their own. Mechanical valves have a high rate of thromboembolism and require lifelong anticoagulation.

Acellular and cellular high-density, collagen-fibril constructs with suprafibrillar organization.

Collagen is used extensively for tissue engineering due to its prevalence in connective tissues and its role in defining tissue biophysical and biological signalling properties. However, traditional collagen-based materials fashioned from atelocollagen and telocollagen have lacked collagen densities, multi-scale organization, mechanical integrity, and proteolytic resistance found within tissues in vivo. Here, highly interconnected low-density matrices of D-banded fibrils were created from collagen oligomers, which exhibit fibrillar as well as suprafibrillar assembly.