Organoid
The technique for growing organoids has rapidly improved since the early 2010s, and The Scientist named it one of the biggest scientific advancements of 2013.
[8] The phenomena of mechanically dissociated cells aggregating and reorganizing to reform the tissue they were obtained from subsequently led to the development of the differential adhesion hypothesis by Malcolm Steinberg.
[12] In 2006, Yaakov Nahmias and David Odde showed the self-assembly of vascular liver organoid maintained for over 50 days in vitro.
[14] In 2009 the Laboratory of Hans Clevers at Hubrecht Institute and University Medical Center Utrecht, Netherlands, showed that single LGR5-expressing intestinal stem cells self-organize to crypt-villus structures in vitro without necessity of a mesenchymal niche, making them the first organoids.
[15] In 2010, Mathieu Unbekandt & Jamie A. Davies demonstrated the production of renal organoids from murine fetus-derived renogenic stem cells.
[20][21] Other significant early advancements included in 2013, Madeline Lancaster at the Institute of Molecular Biotechnology of the Austrian Academy of Sciences established a protocol starting from pluripotent stem cells to generate cerebral organoids that mimic the developing human brain's cellular organization.
[23] In 2014, Artem Shkumatov et al. at the University of Illinois at Urbana-Champaign demonstrated that cardiovascular organoids can be formed from ES cells through modulation of the substrate stiffness, to which they adhere.
Cerebral organoids are created by culturing human pluripotent stem cells in a three-dimensional structure using rotational bioreactor and develop over the course of months.
Cerebral organoids may experience "simple sensations" in response to external stimulation and neuroscientists are among those expressing concern that such organs could develop sentience.
[30][31][32] In 2023, researchers have built a hybrid biocomputer that combines laboratory-grown human brain organoids with conventional circuits, and can complete tasks such as voice recognition.
[27] These adult stem cell-derived organoids are often referred to as enteroids or colonoids, depending on their segment of origin, and have been established from both the human and murine intestine.
[48] Or recently, Sakib, S., and Zou, S. developed graphene oxide nanoparticles for delivering siRNA regulating expression of tumor necrosis factor-α, that aimed to treat intestinal organoids exhibiting an inflammatory phenotype.
[52][53] In addition, the polarity of intestinal organoids can be inverted,[54] and they can even be dissociated into single cells and cultured as 2D monolayers[55][56] in order to make both the apical and basolateral sides of the epithelium more easily accessible.
Gastric organoids have been generated directly from pluripotent stem cells through the temporal manipulation of the FGF, WNT, BMP, retinoic acid and EGF signalling pathways in three-dimensional culture conditions.
[65] 3D organoid models of brain cancer derived from either patient derived explants (PDX) or direct from cancer tissue is now easily achievable and affords high-throughput screening of these tumors against the current panel of approved drugs form around the world.Self-assembled cell aggregates consisting of BMECs, astrocytes, and pericytes are emerging as a potential alternative to transwell and microfluidic models for certain applications.
[83] These CRISPR-modified pluripotent stem cells were subsequently grown into human kidney organoids, which exhibited disease-specific phenotypes.
When cultured in the absence of adherent cues (in suspension), these cysts reached sizes of 1 cm in diameter over several months.
[103] Kidney organoids with mutations in a gene linked to focal segmental glomerulosclerosis developed junctional defects between podocytes, the filtering cells affected in that disease.
[104] Importantly, these disease phenotypes were absent in control organoids of identical genetic background, but lacking the CRISPR mutations.
[83][103][104] Comparison of these organoid phenotypes to diseased tissues from mice and humans suggested similarities to defects in early development.
[103][104] As first developed by Takahashi and Yamanaka in 2007, induced pluripotent stem cells (iPSC) can also be reprogrammed from patient skin fibroblasts.
[107][108][109] Comparison of a patient iPSC derived organoid against an isogenic control is the current gold standard in the field as it permits isolation of the mutation of interest as the only variable within the experimental model.
[108] Another report utilising an isogenic control demonstrated abnormal nephrin localisation in the glomeruli of kidney organoids generated from a patient with congenital nephrotic syndrome.
Studies by the laboratory of Jeffrey Beekman (Wilhelmina Children's Hospital, University Medical Center Utrecht, The Netherlands) described in 2013 that stimulation of colorectal organoids with cAMP-raising agonists such as forskolin or cholera toxin induced rapid swelling of organoids in a fully CFTR dependent manner.
The self-renewal and regenerative properties of intestinal organoids make them promising candidates for transplantation therapies, particularly for disease involving epithelial barrier disruption.
[118] In central nervous system development, for example, organoids have contributed to our understanding of the physical forces that underlie retinal cup formation.
