As Madeline Lancaster lifts a clear plastic dish into the light, roughly a dozen clumps of tissue the size of small baroque pearls bob in a peach-colored liquid. These are cerebral organoids, which possess certain features of a human brain in the first trimester of development—including lobes of cortex. The bundles of human tissue are not exactly “brains growing in a dish,” as they’re sometimes called. But they do open a new window into how neurons grow and function, and they could change our understanding of everything from basic brain activities to the causes of schizophrenia and autism. __ MIT Technology Review (via NextBigFuture)
Now scientists can directly see how networks of living human brain cells develop and function, and how they’re affected by various drug compounds or genetic modifications. And because these mini-brains can be grown from a specific person’s cells, organoids could serve as unprecedentedly accurate models for a wide range of diseases. __ Technology Review
Initially, the main use of these “organoids” is in research: To learn how diseases develop, and to gauge the response of specific tissues to interventions such as drugs, and other more basic research into organ development. As the methodologies for growing “organs in a dish” become more sophisticated over time, eventually it will be possible to grow replacement tissues for diseased or degenerated organs — even entire replacement organs.
When organoids are grown on a dish from induced pluripotent stem cells, they already have the ability to “self-organise.”
This is just the beginning, says Lancaster. Researchers such as Rudolph Jaenisch at MIT and Guo-li Ming at Johns Hopkins are beginning to use brain organoids to investigate autism, schizophrenia, and epilepsy. What makes cerebral organoids particularly useful is that their growth mirrors aspects of human brain development. The cells divide, take on the characteristics of, say, the cerebellum, cluster together in layers, and start to look like the discrete three-dimensional structures of a brain. If something goes wrong along the way—which is observable as the organoids grow—scientists can look for potential causes, mechanisms, and even drug treatments.
… The number of possible applications grows with each advance. Most tantalizing to Lancaster herself is the prospect that cerebral organoids might solve the deepest of mysteries: what happens in our brains to set us apart from other animals? “I’m mainly interested,” she says, “in figuring out what it is that makes us human.” ___ MIT Tech Review
…organoids have the potential to provide alternative approaches to cell or even whole organ replacement strategies in the clinic (Fig. 4). Organoids could provide a source of autologous tissue for transplantation. In this respect, renal organoids hold enormous therapeutic potential as this is the organ with the highest rate of end-stage failure leading to the highest organ demand for transplants. Already, Taguchi et al succeeded in transplanting kidney organoids under the renal capsule of adult mice, which led to vascularization, a promising step toward a replacement strategy (29). Additionally, retinal organoids could be used to treat certain types of retinal degeneration and blindness. Indeed, stem cell–therapy clinical trials are already under way to replace certain degenerating retinal cell types (88). Retinal organoids could provide an alternative approach that may better recapitulate development and, therefore, produce particular cell types of interest for transplantation. Finally, intestinal organoids could provide a treatment option for replacement of damaged colon after injury or following removal of diseased tissue. Remarkably, intestinal organoid transplantation has already been performed in mice and can contribute to colon repair after injury (35, 89).
Organoid approaches could even allow for gene correction in the case of genetic defects, using modern genome-editing technologies to replace damaged organ with repaired tissue.
Although it is clear that there are many potential uses for organoids, it is important to keep in mind their current limitations. In particular, all of the organoid systems so far established remain to be thoroughly characterized with regard to the extent of recapitulation of in vivo development. For example, although retinal organoids nicely display typical laminar organization, outer segments fail to form; for example, photoreceptors fail to fully mature to become light-sensitive. Likewise, cerebral organoids recapitulate fairly early events in brain development, but later features, such as cortical plate layers, fail to fully form. _Science Review PDF
There are many hurdles remaining before entire replacement organs can be grown in the lab. An earlier article on Al Fin Longevity blog describes some of the obstacles needing to be overcome.