In people with type 1 diabetes, the immune system mistakenly destroys the pancreatic beta cells responsible for producing insulin. Patients therefore require lifelong insulin therapy to regulate their blood glucose levels.

Transplanting healthy beta cells could potentially restore the body’s ability to produce insulin. However, the recipient’s immune system may rapidly recognize and destroy the transplanted cells. Although immunosuppressive drugs can reduce this rejection, their long-term use increases the risk of serious complications, including infections and certain cancers.

Researchers from Koç University investigated whether gene editing could make transplanted beta cells more resistant to immune attack. Their study focused on two genes, RNLS and HIVEP2, which previous research had identified as possible targets for protecting beta cells from autoimmune destruction.

The research was conducted by İsmail Can Karaoğlu, Arda Odabaş, Prof. Dr. Tamer Önder and Prof. Dr. Seda Kızılel from Koç University’s Department of Chemical and Biological Engineering, School of Medicine and Research Center for Translational Medicine.

Using CRISPR-Cas9 gene-editing technology, the researchers separately disabled RNLS and HIVEP2 in mouse and human beta-cell lines. They then assembled the edited cells into uniform, three-dimensional clusters known as beta-cell spheroids. These structures more closely resemble the cellular organization of pancreatic islets than conventional two-dimensional cell cultures.

Before transplantation, the team tested whether the genetic modifications affected the cells’ ability to respond to glucose and produce insulin. Disabling HIVEP2 did not significantly alter beta-cell function, while the loss of RNLS caused a modest reduction in glucose-stimulated insulin secretion in mouse cells.

The edited beta-cell spheroids were subsequently transplanted under the skin of immunocompetent mice. Mouse-derived cells were used to model rejection between genetically different individuals of the same species, while human cells were used to examine rejection between different species.

The researchers monitored the transplanted cells using bioluminescence imaging. Neither RNLS nor HIVEP2 deletion prolonged the survival of the grafts. The edited cells were rejected at rates similar to those of unedited control cells. Human beta-cell grafts were eliminated more rapidly than mouse grafts, but both were ultimately cleared by the immune system regardless of which gene had been disabled.

The findings demonstrate that disrupting either RNLS or HIVEP2 alone is not sufficient to protect beta-cell grafts from the multiple immune mechanisms involved in transplant rejection. Although these genes may influence particular autoimmune or cellular stress pathways, targeting a single gene does not provide broad protection against allogeneic or cross-species immune responses.

By establishing the limitations of these two targets, the study helps narrow the search for more effective approaches. The researchers suggest that durable protection may require combinations of genetic modifications or the integration of gene editing with immunomodulatory biomaterials.

Such strategies could ultimately contribute to the development of beta-cell replacement therapies that restore insulin production while reducing or eliminating the need for lifelong immunosuppressive medication.