Limbal stem cell deficiency (LSCD) is a disease resulting from the loss or dysfunction of epithelial stem cells, which seriously impairs sight. Autologous limbal stem cell transplantation is effective in unilateral or partial bilateral disease but not applicable in total bilateral disease. An allogeneic source of transplantable cells for use in total bilateral disease can be obtained from culture of donated cadaveric corneal tissue. We performed a controlled multicenter study to examine the feasibility, safety, and efficacy of allogeneic corneal epithelial stem cells in the treatment of bilateral LSCD. Patients were randomized to receive corneal epithelial stem cells cultured on amniotic membrane (AM): investigational medicinal product (IMP) or control AM only. Patients received systemic immunosuppression. Primary endpoints were safety and visual acuity, secondary endpoint was change in composite ocular surface score (OSS). Sixteen patients were treated and 13 patients completed all assessments. Safety was demonstrated and 9/13 patients had improved visual acuity scores at the end of the trial, with no significant differences between IMP and control groups. Patients in the IMP arm demonstrated significant, sustained improvement in OSS, whereas those in the control arm did not. Serum cytokine levels were measured during and after the period of immune suppression and we identified strongly elevated levels of CXCL8 in the serum of patients with aniridia, which persisted throughout the trial. This first randomized control trial of allogeneic corneal epithelial stem cells in severe bilateral LSCD demonstrates the feasibility and safety of this approach. Stem Cells Translational Medicine 2019;8:323–331

Different manufacturers use several different processes for the production of intravenous immunoglobulin. Several manufacturers include a production step where the immunoglobulin is treated with low levels of pepsin at pH 4. A series of experiments were undertaken to assess whether or not pH 4/pepsin treatment could inactivate a range of test viruses. Acid-labile viruses such as vaccinia, herpes simplex, mumps and Semliki Forest virus were found to be susceptible to pH 4/pepsin treatment whereas poliovirus type 2, an acid-stable virus, was completely resistant to this treatment. In immunoglobulin preparations, viral contaminants are likely to be present as antibody/virus complexes and such complexing was found to help protect the test viruses from inactivation by pH 4/pepsin treatment. Despite this protection, at least 99% of the test inoculum of two susceptible viruses (vaccinia and herpes simplex) was found to be inactivated after treatment and the subsequent dissociation of virus/antibody complexes. It is concluded that pH 4/pepsin treatment may contribute to the safety of intravenous IgG by inactivating potential viral contaminants.

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