Parathyroid in vitro
Parathyroid Organoids will Help in drug screening
Anna Devyataykina, PCR.news
The parathyroid glands are small endocrine organs that secrete parathyroid hormone (PTH) into the blood. This hormone is important for maintaining the level of calcium in the body — an element necessary for the nervous, muscular and skeletal systems. In diseases of the parathyroid gland, PTH synthesis changes and calcium homeostasis is disrupted, which leads to the development of serious pathologies. Researchers from the Medical Center of the University of Groningen (Netherlands) have developed an in vitro model of the parathyroid gland. They created an organoid culture from parathyroid organoids (PTO) stem cells and evaluated its potential for drug testing.
To begin with, scientists created the organoid culture itself. To do this, they divided (mechanically and enzymatically) the thyroid gland material with hyperplasia obtained from 50 patients after surgery into individual cells and their clusters. Then these cells were cultured, their self-renewal potential and the effectiveness of organoid formation were evaluated. The cells were indeed updated, which confirms the presence of stem cells in cultures, and also continued to secrete PTH and parathyroid marker genes.
Next, the researchers tested the ability of the resulting stem cells to differentiate. To do this, they were exposed to a modified Bingham protocol, which in previous studies directed cells along the path of differentiation of the parathyroid gland. Two weeks later, the modified cells secreted significantly more PTH.
Then, using RNA sequencing, PTO and differentiated PTO (differentiated PTO, dPTO) were compared with thyroid cells of patients. Of the estimated 14,900 genes in PTO cells, only 25 genes were overregulated and 61 were suppressed, and in dPTO — 50 and 82 genes, respectively. Two of the 35 thyroid marker genes were expressed differently in PTO and dPTO tissues. And when analyzing the supposed marker genes of stem cells, no differences were found in PTO and dPTO compared to the tissue of patients. Thus, the similarity of the obtained cultures with the original one turned out to be quite high, especially in tissue-specific genes.
The functional activity of the obtained PTO was also evaluated. PTH secretion was suppressed by a high concentration of extracellular calcium. So the cells were functionally active.
In addition, PTO responded to medications in the same way as in the treatment of patients. Cinacalcet and calcitriol (drugs used for hyperparathyroidism) were expected to reduce PTH production compared to control cells.
Finally, using positron emission tomography (PET) and single-photon emission computed tomography (SPECT), the authors showed that the cultured PTO were patient-specific.
This is the first study to develop a technique for cultivating an organoid culture of the thyroid gland grown from tissues obtained from patients. The resulting culture is phenotypically similar to the original tissue, is functionally active and responds to the action of drugs. Such a model can be useful for understanding the mechanisms of disease development and searching for new therapeutic targets.
Article by Noltes et al. Patient-derived parathyroid organoids as a tracer and drug-screening application mode is published in the journal Stem Cell Reports.
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