Application of microtechnologies for the vascularization of engineered tissues

While in class we discussed angiogenesis and how stopping it is a new area of research to kill cancer, I started to think in the other direction. I wondered what research is being done to promote it, and how it can be used to help people. I found the following article on promoting vasculature during tissue engineering using microscale components. One of the major limiting factors in the field of tissue engineering is the difficulty to generate functional 3D tissues due to the inability to integrate vascular structures into scaffolds. Building networks of vessels branched together into a complex interconnected structure connecting across multiple length scales remain one of the greatest challenges in tissue engineering. Most cells in the human body are within a few hundred microns from a capillary, allowing the delivery of adequate nutrients and supplies to the tissues and organs. Since most tissue engineering scaffolds are unable to provide such proximity for continuous solutes and oxygen flow, the engineering of large tissues severely lacks from diffusion and transport properties. The methods currently investigated to generate vasculature in scaffolds mainly involve the use of proangiogenic growth factors and cell-based approaches, which have shown promising results in vivo, but still cannot provide inlet and outlet vessels for in vitro perfusion. Despite all the advances in microfluidics, the use of microengineered 3D structures comprised of rationally designed and microfabricated channels offer limited functionality. These platforms do not provide a parenchymal space for cell types other than endothelial cells to grow within the constructs and present an integration problem with the host tissue. Modular and bottom-up approaches have recently emerged as promising biofabrication approaches in which functional microscale tissue building blocks can be assembled into 3D macroscale tissue constructs. These are relatively simple methods that allow the production of perfusable tissue, with precise control over the microscale features in a 3D construct. They are particularly promising in the case of organ engineering, where tissue requires perfusion and needs to perform a specialized physiological function. The precise design of microscale components in a high-throughput fashion combined with the capability to link these components together to generate larger structures represents a promising way to build vascularized 3D structures. Therefore, combining modular assembly methods with microfabrication technologies to engineer tissues and organs represent an effective method to control tissue architecture both at the micro and macroscale.

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3236112/