Ex vivo and in vivo modulatory effects of umbilical cord Wharton's jelly stem cells on human oral mucosa stroma substitutes

Novel oral mucosa substitutes have been developed in the laboratory using human umbilical cord Wharton's jelly stem cells -HWJSC- as an alternative cell source. In the present work, we have generated human oral mucosa substitutes with oral mucosa keratinocytes and HWJSC to determine the influence of these cell sources on stromal differentiation. First, acellular and cellular stroma substitutes and bilayered oral mucosa substitutes with an epithelial layer consisting of oral mucosa keratinocytes -OM samples- or HWJSC -hOM- were generated. Then, tissues were analyzed by light and electron microscopy, histochemistry and immunohistochemistry to quantify all major extracellular matrix components after 1, 2 and 3 weeks of ex vivo development, and OM and hOM were also analyzed after in vivo grafting. The results showed that bioengineered oral mucosa stromas displayed an adequate fibrillar mesh. Synthesis of abundant collagen fibers was detected in OM and hOM after 3 weeks, and in vivo grafting resulted in an increased collagen synthesis. No elastic or reticular fibers were found. Glycoprotein synthesis was found at the epithelial-stromal layer when samples were grafted in vivo. Finally, proteoglycans, decorin, versican and aggrecan were strongly dependent on the in vivo environment and the presence of a well-structured epithelium on top. The use of HWJSC was associated to an increased synthesis of versican. These results confirm the usefulness of fibrin-agarose biomaterials for the generation of an efficient human oral mucosa stroma substitute and the importance of the in vivo environment and the epithelial-mesenchymal interaction for the adequate differentiation of the bioengineered stroma.

Sequential keratinocytic differentiation and maturation in a three-dimensional model of human artificial oral mucosa

BACKGROUND AND OBJECTIVE

Oral mucosa shortage may limit or condition some clinical approaches in maxillofacial, periodontal and implant treatment. The availability of a human oral mucosa model generated by tissue engineering could help clinicians to address the lack of oral mucosa. In this work, we carried out a sequential maturation and differentiation study of the epithelial cell layer of an artificial human oral mucosa substitute based on fibrin-agarose biomaterials with fibroblasts and keratinocytes.

MATERIAL AND METHODS

Histological, immunohistochemical and gene expression analyses were carried out in artificial human oral mucosa models developed and cultured for 1, 2 and 3 wk.

RESULTS

Artificial oral mucosa models showed expression of tight junction proteins and cytokeratins from the first week of in vitro development. Mature samples of 3 wk of development subjected to air-liquid conditions showed signs of epithelial differentiation and expressed specific RNAs and proteins corresponding to adherent and gap junctions and basement lamina. Moreover, these mature samples overexpressed some desmosomal and tight junction transcripts, with gap junction components being downregulated.

CONCLUSION

These results suggest that bioengineered human oral mucosa substitutes form a well-developed epithelial layer that was very similar to human native tissues. In consequence, the epithelial layer could be fully functional in these oral mucosa substitutes, thus implying that these tissues may have clinical usefulness.

Expression of epithelial markers by human umbilical cord stem cells. A topographical analysis

INTRODUCTION

Human umbilical cord stem cells have inherent differentiation capabilities and potential usefulness in regenerative medicine. However, the epithelial differentiation capability and the heterogeneity of these cells have not been fully explored to the date.

METHODS

We analyzed the expression of several undifferentiation and epithelial markers in cells located in situ in different zones of the umbilical cord -in situ analysis- and in primary ex vivo cell cultures of Wharton's jelly stem cells by microarray and immunofluorescence.

RESULTS

Our results demonstrated that umbilical cord cells were heterogeneous and had intrinsic capability to express in situ stem cell markers, CD90 and CD105 and the epithelial markers cytokeratins 3, 4, 7, 8, 12, 13, 19, desmoplakin and zonula occludens 1 as determined by microarray and immunofluorescence, and most of these markers remained expressed after transferring the cells from the in situ to the ex vivo cell culture conditions. However, important differences were detected among some cell types in the umbilical cord, with subvascular zone cells showing less expression of stem cell markers and cells in Wharton's jelly and the amnioblastic zones showing the highest expression of stem cells and epithelial markers.

CONCLUSIONS

These results suggest that umbilical cord mesenchymal cells have intrinsic potential to express relevant epithelial markers, and support the idea that they could be used as alternative cell sources for epithelial tissue engineering.