An African frog, which was used decades ago as a pregnancy test, is being used to investigate strategies to regenerate the spinal cord. The studies, which are expected to have therapeutic application in humans, are led by Dr. Juan Larrain, a principal researcher at the Center for Aging and Regeneration CARE Chile UC.

Dr.-Juan-LarraínMotivated to know how an animal is formed during embryonic development, Dr. Larrain came to investigate this species, which in their tadpole state has the amazing ability to regenerate their spinal cord.This is unlike what happens with young and adult frogs and also with mammals. “We are the only group in the world that has established this model to study the regeneration of the nervous system. One of the great advantages is that this has allowed us to make comparisons at the genetic, cellular, and biochemical levels on the mechanisms through which the tadpole triggers this process and understand why juvenile frogs do not, “says the scientist and Vice Chancellor at the Catholic University of Chile.

Regain mobility: the dream

The main objective of the studies conducted for the last six years, is to help the recovery of nervous system tissues in humans, applying the knowledge described in amphibians, and analyzing the use of new compounds; this, together with the hope of being able to combat certain diseases and especially to improve the quality of life of people who have suffered damage to the spinal cord. “The dream is that this knowledge will be transformed into therapies that improve the quality of life of people with paraplegia, for example, helping to generate small recoveries of mobility, for instance, in a limb,” says the UC academic.

When there is damage to the spinal cord, which can be caused by accidents, attacks or bullet injuries, among other things, cell death is generated in the nervous system, explains Larraín, which affects dramatically the tissues responsible for transmitting messages between the brain and the body. In this context, supporting the rehabilitation of these patients is a major challenge in this laboratory composed of fifteen researchers. However, the knowledge could eventually be used in other applications.  “Many other diseases, including Alzheimer’s and diabetes, are caused by tissue death ,” explains the CARE researcher.

Findings and therapeutic compounds

Rana-Africana-1Converting to the African clawed frog, Xenopus laevis, a model organism for the CARE study, it is a milestone given its history and past in the scientific world; Many years ago, this species was used as a pregnancy test, as discovered by an English scientist. The test involved injecting this frog with a urine sample from potentially pregnant women. When the test was positive, the hormone secreted by the woman could induce ovulation in the animal, stimulating egg-laying within 24 hours. “Afterward, this frog became a research model and today, in this laboratory, it is our test tube,” specifies Dr. Larraín.

As for the findings in tadpoles, the scientist explains that certain key processes and mechanisms have already been identified. “We have established that in response to injury, regenerative animals massively activate the division of adult neural stem cells, which proliferate and repair the damage. Such cells are engines for regeneration,” he says. In small amphibians, they have also observed that the metabolic and immune system responses are different than those in adult frogs. In this context, one bet is to “modify the response in the adult frog by imitating what happens in tadpoles,” says the scientist.

In this framework, CARE researchers are also developing another line of research that will test a series of compounds in these frogs, elements that could have therapeutic efficacy. “We are testing two growth factors, or natural compounds, to see if they have the capacity for regeneration in the adult frog. We are optimistic and hope that in the coming years we can accomplish beneficial effects. If that happens, there will come a critical phase of testing the therapies in mammals,” he says.

This laboratory also won a FONDEF project, which seeks to establish the African frog as a working model to test regeneration strategies by also considering a number of benefits, ranging from its appearance and ease of manipulation to its low cost.


The findings developed by Dr. Larrain, also seek interaction with other laboratories. Among them is Dr. Francisca Bronfman, also a researcher at CARE, who conducts studies on axonal regeneration. In Chile, other collaborations are conducted in conjunction with the University of Concepción. Internationally, CARE has also shown broad participation in conferences and seminars outside of Chile on regenerative biology. “This is an area that, over the years, has been moving more and more and we have had good reception. Last year we were at the Center for Regenerative Medicine in Australia, and we have also established partnerships with teams in countries like England, the United States and Uruguay .We do experiments with them all and the interaction always helps us a lot. Moreover, most of our students spend several months abroad doing their studies,” says the researcher.

Thanks to these interactions, great optimism in the research have been created, together with the current project to create a Ministry of Science and Technology in our country. “Science in Chile has been developed through the efforts of many but requires a medium and a long term plan an organizational structure that allows us to visualize and coordinate this program. This, together with the financing required. Therefore, we hope that this project really can continue to progress,” he says. (By Carolina Ines Todorovic, Llambías Communications Agency.).