3. Preparation of taste bud organoids
Many applications of human cancer models including cancer cell lines and
patient-derived tumor xenografts (PDX) had emerged[13,63]. In these
models, the primary tumor tissues were transplanted into immunodeficient
mice[64,65]. PDX can better retain the complexity and heterogeneity
of parental tumors, but it is still difficult to establish because of
the high cost of analysis and long construction cycle. In recent years,
patient-derived organoid (PDO) have made significant progress. The
formation process of organoids is divided into self-mode events and
morphogenesis rearrangements, which involve different
mechanisms[66]. Any disturbance of physical or chemical signals may
affect the acquisition of organoids. The earliest successful cultivation
of taste organoids was based on fluorescence-activated cell sorting
(FASC)[67]. Transgenic mice were used to screen out
Lgr5+ cells, then taste bud was obtained ex
vivo . It is proved that the obtained taste organoids contain
proliferation and mature taste cells. Furthermore, the author used
circumvallate papilla tissue to establish taste bud organoids[68].
Therefore, different preparation approaches can obtain taste bud
organoids, but it seems that the tissue-derived approach is simpler and
time-saving.
3.1 Stem/progenitor cell-derived approach
Taste bud organoids derived from stem cells only select stem/progenitor
cells of taste cells for culture, thereby obtaining a more unitary
culture system. Meanwhile, the stem/progenitor cell-derived culture
method requires the labeling of taste progenitor cells in advance
(Figure 3a). These cells are then sorted using FACS and cultured
individually (Figure 3b-c). Finally, taste bud organoids can be achieved
(Figure 3d). Inoculating taste cells on the sensor to simulate the
perception of complex tastes to construct an artificial tongue model is
the first utilization of taste cells to cultivate a tongue organ modelin vitro . The system detects tastants through high-efficiency
functional receptors and provides ideas for artificial taste devices for
taste perception and taste information standardization[9]. Moreover,
in terms of disease treatment, taste bud organoids are able to mimic the
state of the body well and produce consistent responses[69]. By
transcriptome sequencing of organoids derived from
Lgr5+ cells, preferential taste cell generation was
age-related [70] and regulated via multiple signaling
pathways[71], [72]which also enriches the signal transduction
network that regulates the production of taste cells and provides a
theoretical basis for the study of the proliferation and differentiation
of taste cells as well as the development mechanism of taste buds.