Generation of (Corneal) Limbal Cells from Somatic Cells- Comparison of Reprogramming and Transdifferentiation

Currently used regenerative medicine technologies provide greatpossibilities for the in vitro-production of organs and tissues and theirtherapeutic replacement. A number of up-to-date methods offer a widerange of natural and synthetic biomaterials to be used as the scaffoldsfulfilling the biomechanical requirements for tissue engineering. Thecellular component of tissues and organs is typically individuallymade from the recipient’s own cells, and hence, the histocompatibilityis impeccably matched – an approach so-called isograft-type transplantation. In the eye, a small pool of tissue stem cells located at thelimbus are responsible for maintaining the corneal epithelium. However,this pool of stem cells may get depleted through certain injuries ordiseases, which may result in the visual impairment. To resolve thisissue, several standard treatment modalities can be applied, includingautologous or allogeneic limbal stem cell (LSC) transplantation.However, the graft rejection and chronic inflammation have beenshown to limit the success rate of such procedure over a long time. Todate, the use of transdifferentiation technology and induced pluripotentstem (iPS) cells have paved the way towards new treatment possibilitiesagainst various diseases with patient-specific cells, eliminating the riskof immune rejection. In the past couple of years, various protocols havebeen established in order to differentiate the iPS cells into the cornealepithelial lineage through mimicking the environmental niche of limbalstem cells. Nevertheless, most applications from the lab into the clinichave been hindered because of the risk of teratoma formation associatedwith the use of iPS cells. Our group has developed an optimized protocolfor the differentiation of iPS cells into the corneal epithelial cells. Havingused such protocol, the obtained cells displayed the expression of cornealepithelial markers showing a successful differentiation. However, theprocess used appeared to be time-consuming while the level of geneexpression for the pluripotency markers did not completely disappear.Therefore, we developed a direct transdifferentiation method to avoidthe intermediate state of pluripotency (iPS-stage). The cells attained bythe direct transdifferentiation of fibroblasts into limbal cells showed themorphology of the corneal epithelial cells and also expressed the keymarkers of these cells. Our findings confirmed that the transdifferentiationprotocol can efficiently perform in comparison with other reprogrammingapproaches with the subsequent differentiation into corneal limbal cells.Taken all, the direct transdifferentiation of human dermal fibroblasts intothe corneal epithelial lineage is proposed to serve as a reliable source forcorneal epithelial cells for the transplantation.

کلیدواژه ها:

Limbal cells ، Somatic cells ، Induced pluripotent stem