There is a significant medical need for tough biodegradable polymer adhesives that can adapt to or recover from various mechanical deformations while remaining strongly attached to the underlying tissue. We approached this problem by using a polymer poly(glycerol-co-sebacate acrylate) and modifying the surface to mimic the nanotopography of gecko feet, which allows attachment to vertical surfaces. Translation of existing gecko-inspired adhesives for medical applications is complex, as multiple parameters must be optimized, including: biocompatibility, biodegradation, strong adhesive tissue bonding, as well as compliance and conformability to tissue surfaces. Ideally these adhesives would also have the ability to deliver drugs or growth factors to promote healing. As a first demonstration, we have created a gecko-inspired tissue adhesive from a biocompatible and biodegradable elastomer combined with a thin tissue-reactive biocompatible surface coating. Tissue adhesion was optimized by varying dimensions of the nanoscale pillars, including the ratio of tip diameter to pitch and the ratio of tip diameter to base diameter. Coating these nanomolded pillars of biodegradable elastomers with a thin layer of oxidized dextran significantly increased the interfacial adhesion strength on porcine intestine tissue in vitro and in the rat abdominal subfascial in vivo environment. This gecko-inspired medical adhesive may have potential applications for sealing wounds and for replacement or augmentation of sutures or staples.chemical cross-link ͉ medical adhesive ͉ nanotopography ͉ surgical suture

There is no technology available to support failing lung function for patients outside the hospital. An implantable lung assist device would augment lung function as a bridge to transplant or possible destination therapy. Utilizing biomimetic design principles, a microfluidic vascular network was developed for blood inflow from the pulmonary artery and blood return to the left atrium. Computational fluid dynamics analysis was used to optimize blood flow within the vascular network. A micro milled variable depth mold with 3D features was created to achieve both physiologic blood flow and shear stress. Gas exchange occurs across a thin silicone membrane between the vascular network and adjacent alveolar chamber with flowing oxygen. The device had a surface area of 23.1 cm(2) and respiratory membrane thickness of 8.7 ± 1.2 μm. Carbon dioxide transfer within the device was 156 ml min(-1) m(-2) and the oxygen transfer was 34 ml min(-1) m(-2). A lung assist device based on tissue engineering architecture achieves gas exchange comparable to hollow fiber oxygenators yet does so while maintaining physiologic blood flow. This device may be scaled up to create an implantable ambulatory lung assist device.

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Over the past two decades, great strides have been made in the field of tissue engineering. Many of the initial attempts to develop an engineered tissue construct were based on the concept of seeding cells onto an avascular scaffold. Using advanced manufacturing technologies, the creation of a preformed vascular scaffold has become a reality. This article discusses some of the issues surrounding the development of such a vascular scaffold. We then examine of the challenges associated with applying this scaffold technology to two vital organ constructs: liver and lung. I n 1985, we hypothesized that a living vital organ could be rationally designed and built for human therapy from cells and degradable polymer scaffolding. This was based on only two pieces of previous work: 1) an acellular artificial dermis by Yannas and Burke (1); and 2) a vascular conduit of contracted collagen and vascular cells (2).Our first reports described the formation of hepatic, intestinal, and pancreatic tissue (3,4). In the ensuing 22 y, the fields of Tissue Engineering and Regenerative Medicine have become established and several tissues are available for human trials or use. In 1998, to overcome the problem of sufficient functional mass for human therapy, we hypothesized that we could build a vasculature as part of the tissue-engineered organ which would provide immediate exchange of oxygenand nutrient-rich blood to the full volume of engineered tissue, much as a transplanted organ functions today. Summarized below are the most recent developments toward an engineered vascularized tissue with emphasis on liver and lung. VASCULARIZED SCAFFOLD FOR SOLID ORGAN TISSUE ENGINEERINGThe fundamental challenge of developing a tissue for therapeutic use is scaling up the growth of cells from a culture dish to a three-dimensional scaffold. Multilayer cellular constructs are achievable on flat sheets or thin porous scaffolds. However, the creation of tissues for solid organ transplantation must overcome the limited distance of oxygen diffusion.One approach is centered on angiogenesis, or the selfassembly of a vascular network within a scaffold by endothelial and smooth muscle cells. Although on a small scale this is achievable, this approach develops too slowly to support the mass of tissue that is required for an organ transplant, such as a liver. The Tissue Engineering and Organ Fabrication Laboratory at Massachusetts General Hospital proposed the creation of a scaffold with an integrated vascular network (5,6). A capillary-like vascular network within a three-dimensional scaffold can deliver oxygenated blood to within several hundred micrometers of all cells in the scaffold. These vascular networks are designed to replicate features of a capillary network within the bounds of what can be manufactured. Initial work centered on the utilization of photolithography techniques to create molds of capillary-like networks (7-12). The vascular networks of these original molds were designed to have arterial pressure drop across the network wit...

Children ≤3 years of age in our cohort safely underwent LH with similar pain scores, complications, and recurrence as OH. Parents and caregivers report high satisfaction with both techniques.