Regenerative medicine of cornea by cell sheet engineering using temperature-responsive culture surfaces

Abstract

Recently, regenerative medicine has been focused on as next-generation definitive therapies for several diseases or injuries for which there are currently no effective treatments. These therapies have been rapidly developed through the effective fusion between different fields such as stem cell biology and biomaterials. So far, we have proposed “cell sheet engineering” through our core technology that simply applies alterations of the temperature which allows regulation of the attachment or detachment of living cells on the culture surfaces grafted with the temperature-responsive polymer “poly(N-isoproplyacrylamide)”. This technology enables us to construct bioengineered sheet-like tissues, termed “cell sheets”, without the need of using biodegradable scaffolds and protease treatments that are traditionally used. Therefore, our carrier-free cell sheets not only are independent of the issues observed in conventional methods, but also showed further advantages in the reconstruction of the corneal epithelium or endothelium (e.g. improvement of optical transparency and cell-cell interactions to host stroma in reconstructed tissues). Moreover, our approach does not have issues such as immune rejection or limited number of donors, due to the use of cell sheets derived from autologous limbal (in patients with unilateral disease) or oral mucosal epithelial cells (in patients with bilateral disorders). Indeed, we have successfully performed the clinical application for the reconstruction of ocular surfaces through the transplantation of our carrier-free corneal epithelial cell sheets, as evidenced by improved visual acuity as well as long-term maintenance of postoperative health conditions on ocular surfaces in all patients. We have also proposed a novel approach for the reconstruction of the corneal endothelium using corneal endothelial cell sheets by demonstrating its successful application. Thus, our cell sheet engineering technique provides a breakthrough in the field of regenerative medicine applied to the cornea.