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Original HIT News interview by Yesle Shim, published on April 3, 2025

“Replacing Primate Testing with Fully Humanized Mice”

During my time as a researcher, I participated in developing a mouse model that expressed human antibodies. Using a highly complex technique called BAC cloning, we inserted the entire set of human antibody genes into mice. However, the model failed to reproduce human immune responses accurately. In the end, we had no choice but to rely on primate testing for efficacy verification, inevitably facing ethical concerns, high costs, and long study durations.

So when I first heard the term “Fully Reconstituted Humanized Mouse,” I was immediately intrigued. Unlike models that humanize specific genes, this approach rebuilds the mouse’s entire immune system with human cells. It fundamentally questions the limitations of conventional preclinical systems. And there was one Korean company that had successfully implemented this technology: Preclina. 

I spoke with CEO Young Mo Kang to learn more about their breakthrough.

Beyond Primate Testing: A Technological Leap in Fully Humanized Mice

From the beginning of the interview, Preclina CEO emphasized that Preclina’s model is fundamentally different from existing approaches. “Targeted humanization, which is widely used in the industry, only humanizes specific antibody genes,” he noted. “That method has clear limitations when it comes to replicating the complex interactions of the human immune system.”

Preclina’s Fully Reconstituted Humanized Mouse eliminates the mouse’s immune system and reconstructs it using human immune cells. By injecting umbilical cord blood-derived hematopoietic stem cells (HSCs) or adult peripheral blood mononuclear cells (PBMCs) into severely immunodeficient mice, the model allows human T cells, B cells, NK cells, and macrophages to differentiate and function within the animal, creating an environment closely resembling the human immune system.

“Our model doesn’t just express human proteins,” Preclina CEO YoungMO Kang explained. “It reproduces the intricate interactions between human immune cells inside the mouse almost identically.” According to him, this enables the accurate evaluation of drug mechanisms and improves the prediction of toxicity by replicating the qualitative complexity of human immune responses.