Partial in vivo reprogramming enables injury-free intestinal regeneration via autonomous Ptgs1 induction.

Tissue regeneration after injury involves the dedifferentiation of somatic cells, a natural adaptive reprogramming that leads to the emergence of injury-responsive cells with fetal-like characteristics. However, there is no direct evidence that adaptive reprogramming involves a shared molecular mechanism with direct cellular reprogramming. Here, we induced dedifferentiation of intestinal epithelial cells using OSKM (Oct4, Sox2, Klf4, and c-Myc) in vivo. The OSKM-induced forced dedifferentiation showed similar molecular features of intestinal regeneration, including a transition from homeostatic cell types to injury-responsive-like cell types. These injury-responsive-like cells, sharing gene signatures of revival stem cells and atrophy-induced villus epithelial cells, actively assisted tissue regeneration following damage. In contrast to normal intestinal regeneration involving Ptgs2 induction, the OSKM promotes autonomous production of prostaglandin E2 via epithelial Ptgs1 expression. These results indicate prostaglandin synthesis is a common mechanism for intestinal regeneration but involves a different enzyme when partial reprogramming is applied to the intestinal epithelium.

Epithelial plasticity enhances regeneration of committed taste receptor cells following nerve injury.

Taste receptor cells are taste bud epithelial cells that are dependent upon the innervating nerve for continuous renewal and are maintained by resident tissue stem/progenitor cells. Transection of the innervating nerve causes degeneration of taste buds and taste receptor cells. However, a subset of the taste receptor cells is maintained without nerve contact after glossopharyngeal nerve transection in the circumvallate papilla in adult mice. Here, we revealed that injury caused by glossopharyngeal nerve transection triggers the remaining differentiated K8-positive taste receptor cells to dedifferentiate and acquire transient progenitor cell-like states during regeneration. Dedifferentiated taste receptor cells proliferate, express progenitor cell markers (K14, Sox2, PCNA) and form organoids in vitro. These data indicate that differentiated taste receptor cells can enter the cell cycle, acquire stemness, and participate in taste bud regeneration. We propose that dedifferentiated taste receptor cells in combination with stem/progenitor cells enhance the regeneration of taste buds following nerve injury.

Fine-tuning of epithelial taste bud organoid to promote functional recapitulation of taste reactivity.

Taste stem/progenitor cells from posterior mouse tongues have been used to generate taste bud organoids. However, the inaccessible location of taste receptor cells is observed in conventional organoids. In this study, we established a suspension-culture method to fine-tune taste bud organoids by apicobasal polarity alteration to form the accessible localization of taste receptor cells. Compared to conventional Matrigel-embedded organoids, suspension-cultured organoids showed comparable differentiation and renewal rates to those of taste buds in vivo and exhibited functional taste receptor cells and cycling progenitor cells. Accessible taste receptor cells enabled the direct application of calcium imaging to evaluate the taste response. Moreover, suspension-cultured organoids can be genetically altered. Suspension-cultured taste bud organoids harmoniously integrated with the recipient lingual epithelium, maintaining the taste receptor cells and gustatory innervation capacity. We propose that suspension-cultured organoids may provide an efficient model for taste research, including taste bud development, regeneration, and transplantation.