![]() ![]() After injury, these segments along with capillaries have limited regenerative capacity, which may contribute to tissue ischemia, tubular dysfunction, inflammation, fibrosis, and the development of chronic kidney diseases. ![]() In fact, the kidney is highly vascular, receives about 25% of cardiac output, and is particularly susceptible to injury due to its dual dynamic functions. The kidney capillaries wrap closely around the nephron, providing nutrient support as well as actively participating in solute exchange. These segments selectively filter, secrete, or reabsorb solutes, regulate the composition and volume of extracellular fluid, and maintain blood pressure. A nephron is composed of multiple segments, beginning with Bowman’s capsule, followed by the proximal tubule in the cortex, loop of Henle in the medulla, distal tubule in the cortex, and collecting ducts toward the ureter. The fundamental functional unit of the kidney is the nephron, with each human kidney containing between 6 × 10 5 and 1.4 × 10 6 nephrons. We will discuss organ-specific cells, matrix sources, and architectures, and highlight the bottlenecks and prospective for organ-specific tissue engineering. We will review advanced tissue engineering techniques that enable engineering organ-specific functional units for drug testing and reconstruction of thick tissue constructs for transplant. In this review, we discuss the unique features and critical engineering challenges to tissue engineering in four major organs, focusing on the organs that top the organ transplant waiting list in the USA: the kidney, the liver, the heart, and the lung. Įach organ varies in its unique structural components-namely different cell types, matrix, and architecture among them, biophysical environment-pressure and flow, and biochemical stimuli-oxygen tension, cytokines, and growth factors, to support the specific organ function. Engineering complex metabolically-demanding tissues, however, requires higher-order organization across interacting functional compartments (e.g., parenchyma and vasculature cells, and matrix), at molecular, cellular and tissue scales, in addition to adequate mass to generate physiological tissue function. Multiple human organs-on-a-chip have been actively developed for the study of drug response and pharmaceutical kinetics. ARE PROTEIN SCAFFOLD ORGANS A VIABLE TRANSPLANT OPTINO SKINClinical success has been achieved in simple flat tissue transplantation, such as skin and bladder, which contain few cell types and require simpler engineering designs. To date, multiple levels of complexity have been achieved with existing technologies to precisely position cells at scales from the single cell to whole tissue-level architectures. For the rest, scientists are working hard to guarantee that much-needed organ donations will no longer go to waste.įor more, visit Wired, and watch this video with the Mayo Clinic’s Dr.Tissue engineering has emerged as a promising approach with two major goals: (1) to develop tissue and organ substitutes for clinical transplantation to replace damaged regions and restore organ function and (2) to build human tissue chips and replace animal models for drug screening and disease modeling. ![]() Of course, kidney transplants are a special case, because, unlike almost all other organs, kidneys can be expendable. Another intriguing fix, although much less scientifically elegant, is to simply “brute force” our way through the organ shortage if enough eligible donors were brave enough to lend a kidney, “spoiled” organ donations would be much less of a problem. Other potential advances involve chemical agents similar to antifreeze. When ice crystals form on the surface of an organ, it’s no good (which should give you some perspective the next time your Rocky Road ices over.) So one potential solution is to continually freeze and unfreeze an organ in such a way that ice will never form. So why is it such a challenge to keep donated organs intact? And while it’s mostly a punchline rather than a viable means of resurrection, it’s also a real technology that can actually preserve some living matter. Cryopreservation, or cryogenic freezing, is infamous for its use by the super-rich (and by cheesy sci-fi characters) as a means of one day coming back to life. Freezing and canning otherwise perishable foods can keep them fresh for months, or even years. The finer details of organ transplantation are likely not something the average person has put much thought into, but the limited capabilities of organ banking seem anomalous in a culture where long-term preservation is such a common part of life. ![]()
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