Purpose
Limbal stem cells play a major role in providing a never-ending supply of corneal epithelial cells. When this is compromised alternative sources need to be found. Dental pulp stem cells(DPSC) have been shown to differentiate into corneal epithelial cells; however their life cycle in vitro is markedly reduced. In this study, we examined certain factors unique to the microenvironment of the limbus, which are believed imperative for stem cell life cycle, were investigated.
Methods
Using a QuasiVivo( Kirkstall Ltd, Yorkshire) flow circuit, we subjected DPSC to shear forces and diffusible factors released by the corneoscleral rims within a 6 well circuit over a 48 hr period. We assessed its role on the proliferation rate and viability of the DPSC by carrying out viability assays and microscopy. GFP transfected DPSC were placed in the flow circuit and the corneal rims were analyzed with fluorescent microscopy and immunocytochemistry to further evaluate its role in the differentiation of DPSC toward corneal eputhelial cells using keratin 3.
Results
Light microscopy revealed greater confluence and proliferation rates from those DPSC subjected to shear forces as compared to the static wells by 32% after 48 hours. The GFP tranfected DPSC appeared to settle at the corneoscleral junction of the corneal rims and expressed cytokeratin 3 on immunocytochemistry
Conclusions
Addressing the physiological cues of the limbal microenvironment in vitro appears to promote greater proliferation and transdifferentiation of DPSC than DPSC in static wells and highlights the importance of the microenvironment in the in-vitro process. Although we need to acquire more knowledge in the aspect of cell health and further transdifferentiation capability and stages, the progress has been exceptional. It gives great hope for regeneration of corneal epithelium by dental pulp stem cell treatments in the near future.