In vitro transdifferentiation of human skin keratinocytes to corneal epithelial cells

miR-222-3p-containing macrophage-derived extracellular vesicles confer gemcitabine resistance via TSC1-mediated mTOR/AKT/PI3K pathway in pancreatic cancer

Gemcitabine resistance limits the efficacy of chemotherapy and maintains a challenge for treatment outcomes. Therefore, we aimed to clarify the downstream mechanisms underlying the role of miR-222-3p delivered by M2 macrophage-derived extracellular vesicles (M2 MDEs) in the chemoresistance of pancreatic cancer (PCa). We separated the mouse macrophages and polarized them to M2 phenotypes, from which the EVs were derived. miR-222-3p was highly expressed in M2 MDEs. M2 MDEs were internalized by PCa cells. miR-222-3p overexpressing M2 MDEs were treated with gemcitabine and co-cultured with PCa cells for in vitro experiments. Co-culture with M2 MDEs enriched with miR-222-3p suppressed the sensitivity to gemcitabine, accompanied by diminished apoptosis and promoted proliferation. Furthermore, the M2 MDEs and PCa cells were injected to mice with gemcitabine exposure for in vivo substantiation. The delivery of miR-222-3p inhibitor by M2 MDEs suppressed tumor growth and elevated sensitivity of cancer cells to gemcitabine. Moreover, miR-222-3p was indicated to target and suppress TSC1 expression, while miR-222-3p activated the PI3K/AKT/mTOR pathway. Together, miR-222-3p-containing M2 MDEs enhance chemoresistance in PCa through TSC1 inhibition and activation of the PI3K/AKT/mTOR pathway.

Replacing the Draize eye test: Impedance spectroscopy as a 3R method to discriminate between all GHS categories for eye irritation

Highly invasive animal based test procedures for risk assessment such as the Draize eye test are under increasing criticism due to poor transferability for the human organism and animal-welfare concerns. However, besides all efforts, the Draize eye test is still not completely replaced by alternative animal-free methods. To develop an in vitro test to identify all categories of eye irritation, we combined organotypic cornea models based on primary human cells with an electrical readout system that measures the impedance of the test models. First, we showed that employing a primary human cornea epithelial cell based model is advantageous in native marker expression to the primary human epidermal keratinocytes derived models. Secondly, by employing a non-destructive measuring system based on impedance spectroscopy, we could increase the sensitivity of the test system. Thereby, all globally harmonized systems categories of eye irritation could be identified by repeated measurements over a period of 7 days. Based on a novel prediction model we achieved an accuracy of 78% with a reproducibility of 88.9% to determine all three categories of eye irritation in one single test. This could pave the way according to the 3R principle to replace the Draize eye test.

Rat limbal niche cells can induce transdifferentiation of oral mucosal epithelial cells into corneal epithelial-like cells in vitro

BACKGROUND

Cultivated oral mucosal epithelial cells (OMECs) are widely used in the treatment of limbal stem cell deficiency (LSCD) for their ocular reconstruction capability. As the most important component of the limbal microenvironment, limbal niche cells (LNCs) play a key role in the direction of stem cell differentiation. In this study, we investigated whether LNCs can induce the transdifferentiation of rat OMECs to corneal epithelial-like cells.

METHODS

We isolated OMECs and LNCs from rats by dispase and collagenase, respectively, to establish a three-dimensional or Transwell coculturing system. NIH-3T3 cells and renewed LNCs were also used as feeder layers in the Transwell system to compare their ability to support the OMECs. The airlift method was used for the culture of OMECs to obtain a stratified epithelial sheet. Cocultured OMECs were characterized by reverse-transcription polymerase chain reaction, Western blotting, hematoxylin and eosin staining, and immunohistochemistry.

RESULTS

The cocultured OMECs showed corneal epithelial-like morphology and expressed the corneal epithelial markers CK12 and Pax6 in most cocultured systems. Furthermore, we found that the expression level of CK12, Pax6, and proliferation marker Ki67 was upregulated when compared with that of other groups by renewing the LNCs in the Transwell system (p < 0.05, n = 3), suggesting that this might be a potential method for improving the efficiency of transdifferentiation. The obtained stratified epithelial sheet expressed CK3 and CK12.

CONCLUSION

Through coculturing OMECs and LNCs in vitro, we successfully cultivated corneal epithelial-like OMECs. This investigation is of great significance for the treatment of LSCD and ocular surface reconstruction.

Transcription factor profiling identifies Sox9 as regulator of proliferation and differentiation in corneal epithelial stem/progenitor cells

Understanding transcription factor (TF) regulation of limbal epithelial stem/progenitor cells (LEPCs) may aid in using non-ocular cells to regenerate the corneal surface. This study aimed to identify and characterize TF genes expressed specifically in LEPCs isolated from human donor eyes by laser capture microdissection. Using a profiling approach, preferential limbal expression was found for SoxE and SoxF genes, particularly for Sox9, which showed predominantly cytoplasmic localization in basal LEPCs and nuclear localization in suprabasal and corneal epithelial cells, indicating nucleocytoplasmic translocation and activation during LEPC proliferation and differentiation. Increased nuclear localization of Sox9 was also observed in activated LEPCs following clonal expansion and corneal epithelial wound healing. Knockdown of SOX9 expression in cultured LEPCs by RNAi led to reduced expression of progenitor cell markers, e.g. keratin 15, and increased expression of differentiation markers, e.g. keratin 3. Furthermore, SOX9 silencing significantly suppressed the proliferative capacity of LEPCs and reduced levels of glycogen synthase kinase 3 beta (GSK-3ß), a negative regulator of Wnt/ß-catenin signaling. Sox9 expression, in turn, was significantly suppressed by treatment of LEPCs with exogenous GSK-3ß inhibitors and enhanced by small molecule inhibitors of Wnt signaling. Our results suggest that Sox9 and Wnt/ß-catenin signaling cooperate in mutually repressive interactions to achieve a balance between quiescence, proliferation and differentiation of LEPCs in the limbal niche. Future molecular dissection of Sox9-Wnt interaction and mechanisms of nucleocytoplasmic shuttling of Sox9 may aid in improving the regenerative potential of LEPCs and the reprogramming of non-ocular cells for corneal surface regeneration.