The giant panda is considered a symbol of endangered species. Researchers have now succeeded in generating induced pluripotent stem cells from connective tissue cells from two giant pandas. These can, among other things, differentiate into germ cells and generate embryonic tissue. The panda bear stem cells thus offer a valuable resource both for research and for the treatment of diseases in giant pandas. The technology can therefore make an important contribution to the conservation of the species.
There are only about 2,000 giant pandas left in the wild. Their habitat is increasingly falling victim to human activities, being divided up and destroyed, making the species endangered. “Current efforts to conserve the giant panda have led to a measurable increase in the population, which is mainly due to habitat protection and captive breeding,” reports a team led by Yuliang Liu from the Research Center for Giant Panda Breeding in Chengdu, China. In 2016, the International Union for Conservation of Nature (IUCN) therefore downgraded the species’ endangered status from “critically endangered” to “vulnerable.” Nevertheless, genetic diversity is declining in numerous isolated panda populations. “The risk of extinction for 15 wild populations is over 90 percent,” write the researchers. “It is absolutely essential to preserve the genetic resources of the giant pandas.”
Reprogramming of fibroblasts
Liu and his team have now chosen a biotechnological approach. “We have succeeded for the first time in successfully generating induced pluripotent stem cells from the giant panda’s fibroblasts,” they report. Two pandas from the research center in Chengdu served as cell donors: the 13-year-old female Xingrong and the 14-year-old male Loubao. The researchers took small tissue samples from the skin of both pandas and isolated some fibroblasts from them.
Through a series of coordinated reprogramming steps, they converted these cells into induced pluripotent stem cells. The researchers developed a species-specific composition of the cell culture and investigated and documented which biochemical signaling networks triggered the pluripotency of the cells and promoted their proliferation. Gene transcription analyses showed that in the induced pluripotent stem cells, 1261 genes were upregulated – including those related to cell division and embryonic development – and 1671 genes were downregulated compared to the original fibroblasts.
Helpful for research, medicine and species conservation
In further experiments, the team tested how different conditions in cell culture affect the differentiation of the stem cells. “Our results show that the giant panda’s induced pluripotent stem cells have the ability to differentiate into different cell types, which represents a remarkable contribution to the repertoire of resources for basic research on giant pandas and the clinical treatment of giant panda diseases,” write Liu and his colleagues.
Among other things, the researchers succeeded in generating so-called embryoids from the stem cells, which consisted of the three tissue types of the embryonic germ layers. “As embryonic material from endangered large mammals is limited, induced pluripotent stem cells represent an unprecedented tool for gaining insights into embryogenesis and organogenesis,” write Liu and his team. “This crucial advance represents a significant step toward our goal of using giant panda induced pluripotent stem cells for in vitro gamete and embryo generation.”
From the researchers’ point of view, this would increase the genetic diversity of giant pandas kept in captivity. “In addition, this innovation offers valuable resources for advanced research on giant panda stem cells, which will significantly promote efforts to preserve this rare species,” say the researchers. “Induced pluripotent stem cells offer a self-renewing, inexhaustible source of material from endangered species and are able to regenerate different cell types as needed.”
Source: Yuliang Liu (Chengdu Research Base of Giant Panda Breeding, Sichuan Province, China) et al., Science Advances, doi: 10.1126/sciadv.adn7724