Successful generation of iPSC lines from bonobos and gibbons

A research group led by Associate Professor Masanori Imamura (Assistant Professor at the Center for the Evolutionary Origins of Human Behavior, Kyoto University at the time of the research) at the Institute of Medical, Pharmaceutical and Health Sciences at Kanazawa University, Doctoral Student Yusuke Hamazaki from the Center for the Evolutionary Origins of Human Behavior, Kyoto University, and Professor Takuya Imamura and Doctoral Student Hiroto Akuta from the Graduate School of Integrated Sciences for Life at Hiroshima University announced on February 20 that they had successfully generated induced pluripotent stem cells (iPSCs) from the great ape bonobo and the small ape gibbon. The group also succeeded in inducing cells that represent the developmental origin of the limb skeleton from these ape iPSCs. The findings are expected to contribute to the fields of evolutionary developmental biology in primates, biodiversity conservation, and zoo veterinary medicine. The results were published in BMC Genomics on December 5.

The research was conducted as part of the "Zoo-wide iPSC Generation Project" in collaboration with Kumamoto Sanctuary, Wildlife Research Center, Kyoto University (Uki City, Kumamoto Prefecture); the Japan Monkey Centre (Inuyama City, Aichi Prefecture); Toyohashi Zoo and Botanical Park (Toyohashi City, Aichi Prefecture); Higashiyama Zoo and Botanical Gardens (Nagoya City, Aichi Prefecture); the Great Ape Information Network (GAIN); Nagoya University; and SOKENDAI (The Graduate University for Advanced Studies). The project aims to address the challenges of treating rare zoo species for which developing therapies is difficult, by utilizing iPSC technology.

The superfamily Hominoidea is comprised of humans, great apes (bonobos, chimpanzees, gorillas, and orangutans) and small apes (gibbons). Bonobos and chimpanzees are the closest living relatives to humans, and comparisons among these species offer insights into traits unique to humans. Small apes, on the other hand, occupy a phylogenetic position intermediate between humans and great apes on one side and monkeys on the other, and are therefore considered important for understanding the evolutionary path from monkeys to humans.

The research group first isolated and cultured peripheral blood mononuclear cells (PBMCs) from surplus blood samples collected from bonobos and chimpanzees during routine health examinations. In addition, fibroblasts were cultured from skin samples taken from five individuals of three gibbon species (white-handed gibbon, Abbott's gray gibbon, and siamang) that had died naturally at zoos.

iPSCs were generated by introducing reprogramming factors into these cells using a method that does not insert foreign genes into the genome.

As a result, iPSC lines were successfully generated from two bonobos, one chimpanzee, one white-handed gibbon, and two siamangs.

The gene expression patterns of the newly generated iPSCs were compared with those of previously established gorilla and orangutan iPSCs. The expression profiles of the iPSCs were found to reflect the phylogenetic relationships of primate evolution, diverging in the order of monkeys, small apes, great apes, and humans.

Species-specific gene expression characteristics were also detected, including differences in expression between "humans" and "bonobos and chimpanzees", as well as expression patterns unique to gibbons.

For the first time in the world, the research group also succeeded in generating limb bud mesoderm cells—the developmental origin of the limb skeleton (the progenitors of arms and legs)—from the ape (bonobo, chimpanzee, and gibbon) iPSCs they had created.

While forelimb and hindlimb lengths are roughly equal in monkeys, apes have longer arms relative to their legs, and in humans the situation is reversed, with legs being longer than arms. These findings are expected to help clarify the mechanisms by which the distinct limb proportions seen in apes and humans evolved.

The "Zoo-wide iPSC Generation Project" aims to achieve conservation of endangered species (through cell banking), preservation of biodiversity, and advancement of zoo veterinary medicine by building cell banks and generating iPSCs from animals in zoos and captive facilities.

Imamura commented: "While iPSCs from humans and chimpanzees can be generated with relative ease, it took more than ten years to generate iPSCs from small apes. Through extensive trial and error, we noticed that 'when reprogramming factors are introduced into small ape cells, most of them die within a short period of time.' We then took the unglamorous, painstaking approach of 'scaling up the cell culture experiments if survival rates and reprogramming efficiency were low,' and that ultimately led to our success."

Journal Information
Publication: BMC Genomics
Title: Generation and transcriptome profiling of bonobo induced pluripotent stem cells using stealth RNA vectors: a tripartite comparative study with humans and chimpanzees
DOI: 10.1186/s12864-025-12400-4