Giant pandas, China’s beloved national treasure known for their distinctive black-and-white coats, are on the brink of endangerment, with just over 1,800 remaining in the wild today. Human activities, such as livestock grazing and road construction, continue to threaten their survival by disrupting their natural habitat. The loss of this iconic umbrella species would trigger a ripple effect throughout the entire ecosystem. 

Above: Giant panda cub sleeping on a branch. Image courtesy of Britannica.

Fighting Extinction

Over the past few decades, conservation efforts have gradually increased the panda population, largely through habitat protection and captive breeding. Despite these successes, 15 populations of giant pandas still face a risk of extinction greater than 90%, demonstrating the urgent need to conserve their genetic resources. To meet this need, researchers isolated and preserved various cell types, including skin fibroblasts, bone marrow mesenchymal stem cells (MSCs), and umbilical cord MSCs, but their limited proliferative capacity and ability to differentiate hinder their use in producing viable gametes. On the other hand, inbreeding or employing traditional assisted reproductive technologies within such a small population leads to a detrimental loss of genetic diversity. Further investigation into the embryonic development of giant pandas could help advance efforts to enhance both population size and genetic variety. 

A New Hope Through iPSCs

A breakthrough is on the horizon with Jing Liu, a stem cell biologist at the Chinese Academy of Sciences, who may have found the key to panda conservation through induced pluripotent stem cells (iPSCs). In a recent study, Liu and his team successfully generated iPSCs from the skin cells of giant pandas. Researchers have already harnessed iPSC technology to conserve other endangered species, including the Sumatran rhinoceros, Grevy’s zebra, and Tasmanian devil. 

The Process

Nearly 20 years ago, researchers successfully turned human and mouse skin cells into pluripotent stem cells (PSCs), which can proliferate indefinitely and develop into any kind of cell, tissue, or organ in the body. 

Above: Sequential transformations from skin fibroblasts to fully functional cells. Image courtesy of BioInformant.

The challenge, however, is that researchers must tailor the process to each new species. This species specificity led to difficulties when Liu and his team initially attempted to apply successful conditions from other species to reprogram pandas’ fibroblasts into PSCs. After a series of trial and error, Liu and his team discovered that introducing a specific microRNA cluster was key in transforming the fibroblasts into iPSCs. Once they modified the growing conditions to include additional molecules, such as transcription factors specific to pandas, the team successfully obtained iPSC clones. 

Next Steps

The team’s next step is to create primordial germ cells (PGCs), precursors to sperm and egg cells. Researchers have already successfully generated PGCs from iPSCs in mice. Obtaining giant panda sex cells using traditional methods has proven challenging in the past. Strict regulations surrounding the living panda population prevent standard egg extraction methods, and the dwindling number of giant pandas makes it difficult to reliably source eggs from recently deceased animals. If researchers can determine how to noninvasively generate PGCs from panda skin cells, they could use the PGCs in conjunction with assisted reproductive technology to augment both the size and diversity of the endangered population.

Final Thoughts

The potential of PSCs extends beyond just aiding panda reproduction—they also hold promise in regenerative medicine, with applications in disease diagnosis and treatment. The ultimate goal is not only to expand the giant panda population but also to improve its overall health. Soon enough, these gentle giants will be able to thrive again in the lush bamboo forests of China. 

Above: Giant panda enjoying bamboo, showcasing its specialized diet that consists primarily of this high-fiber plant. Image courtesy of Science.