◎Reporter Dai Xiaopei
The researchers found that 5SM can significantly improve cardiac function in adult rats after myocardial infarction, reduce the area of cardiac fibrosis, and promote the conversion of cardiomyocyte metabolism from oxidative phosphorylation to glycolysis by activating lactate signaling and mTOR pathway, and finally induce Cardiomyocyte proliferation and division.
Cardiovascular disease is a serious threat to human health.
Among them, myocardial infarction (myocardial infarction) can lead to massive death of cardiomyocytes, while the remaining cardiomyocytes have limited regenerative capacity, eventually leading to cardiac fibrosis and heart failure.
Promoting the regeneration of myocardial cells has become the key to the recovery of myocardial infarction patients.
Recently, a team of Professor Xiong Jingwei from the School of Future Technology of Peking University, Professor Lei Xiaoguang from the School of Chemistry and Molecular Engineering of Peking University, and Professor Zhao Shimin of Fudan University published a study in the journal Cell Stem Cell, which is the first international report of 5 The combination of these small molecules can effectively promote the regeneration of adult rat heart and play a certain role in the treatment of myocardial infarction.
Facing the worldwide challenge of mammalian heart regeneration
For severe myocardial infarction, there are generally two clinical responses. One is to implant stents to open up the blocked blood vessels and promote blood flow to the area of myocardial infarction, thereby relieving the symptoms of myocardial ischemia; the other is to take it to protect the heart. Drug.
"But neither of these two methods can restore the myocardial cells lost due to myocardial infarction. The mortality rate of patients with severe myocardial infarction is as high as 50% within 3-5 years." Xiong Jingwei said.
"In the past 20 years, there has not been much progress in the research and development of drugs for the treatment of myocardial infarction in the world." Xiong Jingwei said in an interview with a reporter from Science and Technology Daily that the development of drugs for the treatment of myocardial infarction has a high cost and a low success rate. Many large pharmaceutical companies have Cut off this program, so the clinical needs of a large number of myocardial infarction patients have been unmet.
Faced with this dilemma, the outside world has great expectations for cardiac regenerative medicine.
Can a damaged heart be regenerated?
This question has not yet been answered.
Xiong Jingwei said that there are many unsolved problems in the field of heart regeneration.
For example, increasing the proliferation of endogenous cardiomyocytes in adult mammals is essential for cardiac regeneration, but the proliferation rate of endogenous cardiomyocytes in adult mammals is very low; another example, endogenous cardiac stem cells are beneficial to promote cardiac regeneration, but have not yet been found Endogenous cardiac stem cells from adult mammals; another example, the use of embryonic stem cells can produce cardiomyocytes in vitro and then transplant them into the body, but its efficiency is low and it is easy to cause arrhythmia and even death.
Solving the worldwide problem of heart regeneration has become the dream of many biomedical scientists.
Previously, researchers found that specific genes and small nucleic acids can promote the regeneration of adult mammalian cardiomyocytes, but there are two problems with this mechanism of promoting cardiomyocyte regeneration: First, the genes and small nucleic acids are used in the process of delivering the genes and small nucleic acids into the human body. The viral vector of the virus may cause side effects and pose a safety risk; second, the expression of these genes or small nucleic acids after delivery to the heart is uncontrollable, there is a risk of tumor formation, and eventually the animal will die.
Some studies have also reported that a single chemical small molecule has a certain role in the treatment of myocardial infarction, but its treatment efficiency is very low.
In addition, other cells in the heart (such as fibroblasts) have been transformed into cardiomyocytes by gene editing, which is very efficient in vitro but inefficient in animals.
Can other paths be opened up?
Xiong Jingwei has been studying zebrafish for a long time. This low-level animal has a "super power" that humans do not have. The zebrafish's heart can fully recover within one to two months after damage. This is because the zebrafish's heart is damaged. During the process, part of the cardiomyocytes will be divided, that is, divided into two, which is "regeneration".
Inspired by zebrafish, Xiong Jingwei wondered: Can mammals, including humans, regenerate damaged hearts through cardiomyocyte division like zebrafish?
Finding a combination of small molecules that induces cardiomyocyte proliferation
In 2016, with the enrollment of a new batch of doctoral students and the enrichment of new technologies, Xiong Jingwei put on the agenda the goal that has been haunting him for many years - to find small chemical molecules that can induce the division of mammalian cardiomyocytes.
The first step is screening, screening qualified small molecules from thousands of chemical small molecules.
"In the past, chemical small molecule libraries were relatively limited, but now they are quite complete. Some libraries reflect the structural diversity of small molecules, while others focus on the druggability of small molecules." Xiong Jingwei introduced that their target small molecules should not only promote the Cardiomyocyte regeneration must also have good druggability, that is, ADME (absorption, distribution, metabolism and excretion) properties and safety that can enter clinical phase I trials, so as to facilitate later drug development work around these small molecules.
The chemical small molecule library they selected with better druggability contains 11,000 small molecules, and if manually screened, the workload is very large.
To solve this problem, the research team used a high-throughput screening system established by Lei Xiaoguang for screening.
In order to "lock in" the small molecule that drives cardiomyocytes to divide in two, the research team used the dual fluorescent cell cycle reporter system FUCCI (marking the S-G2-M phase of mitosis) and MADM (indicating cytokinesis). The FUCCI reporter system is very sensitive , qualified small molecules will be quickly marked, and the MADM system can further verify the effect of small molecules on promoting cell division into two.
"The high-throughput screening system and sensitive reporting system have improved the screening efficiency. What used to take three years to complete, now one or half a year is enough." Xiong Jingwei said.
Finally, the research team found 13 candidate small molecules after 6 rounds of screening.
"However, these 13 small molecules can only effectively induce cardiomyocytes to enter the cell cycle, and cannot induce the cytokinesis process that divides into two. Later, we wanted to combine candidate small molecules and then verify their effects. , but the number of 13 small molecule combinations is too many, our strategy is to first verify the effect of the pairwise combination." said Zheng Lixia, the co-first author of the above research paper and a doctoral student at Peking University.
Zheng Lixia introduced that based on the effect of the pairwise combination, they further combined the mathematical model to predict the combination of small molecules with the best effect of promoting proliferation, and verified through in vitro and in vivo experiments that the combination of phenylephrine hydrochloride, baricitinib, and dehydrocamelpinine The small molecule combination 5SM composed of , VO-Ohpic trihydrate and AZD3965 can successfully induce adult rat cardiomyocytes to re-enter the cell cycle and undergo cytokinesis.
After completing the in vitro experiments, the efficacy of the small molecule combination 5SM in vivo must also be verified.
According to Zheng Lixia, because the in vivo and in vitro methods of administration, dosage and frequency of administration will be different, they have experimented many times and adjusted the method of administration, and finally overcome the problem, proving that 5SM can also play a role in the body.
The researchers found that 5SM can significantly improve cardiac function in adult rats after myocardial infarction, reduce the area of cardiac fibrosis, and promote the conversion of cardiomyocyte metabolism from oxidative phosphorylation to glycolysis by activating lactate signaling and mTOR pathway, and finally induce Cardiomyocyte proliferation and division.
Myocardial infarction patients are expected to use small molecule combination chemical drugs
The results of this research are the first to discover a combination of small-molecule drugs that promote cardiac regeneration in the world, revealing new cellular and molecular mechanisms in the field of cardiac regeneration, and are expected to find candidate small-molecule drugs for the treatment of myocardial infarction.
Xiong Jingwei said: "A very important discovery is that these small molecules we found do not act through the current mainstream Yap pathway and MAPK pathway, but by changing the metabolism of cardiomyocytes, which is consistent with previous studies. Cardiomyocytes regenerate differently."
Regarding the research results, Nie Yu, a researcher at the State Key Laboratory of Cardiovascular Diseases, Fuwai Hospital, Chinese Academy of Medical Sciences commented: "This research achievement is of great significance. It is the first in the world to induce cardiomyocyte proliferation in situ through a combination of compounds. Research results. Using compounds to promote heart regeneration is a way that everyone is looking forward to because it is safer."
Xiong Jingwei said that next, the research team will further study the mechanism by which these small molecules work. At the same time, based on this theoretical achievement, some new technologies will be developed to provide new ideas and strategies for the development of drugs for the treatment of myocardial infarction, and to develop clinical drugs. R&D work.
"We already know which of the five small molecules has the greatest effect, and we want to find one or two of the other four small molecules to play an auxiliary role, and develop new drugs accordingly. If the efficacy of the drug is proved in the experiment, we will promote the clinical trial and strive to apply for the relevant approval from the State Food and Drug Administration within two years. If it goes well, it is estimated that after 5-8 years, we are expected to see myocardial infarction patients using the drug in the treatment. Combining chemical drugs with small molecules." Xiong Jingwei is looking forward to this.
In addition, this research result will bring some enlightenment to other fields of regenerative medicine research.
Xiong Jingwei said that these small molecule combinations may provide references for research on regeneration issues in other fields such as neuron regeneration, kidney regeneration, and skeletal muscle regeneration.
"I think its enlightening effect is reflected in two aspects: first, to promote the regeneration of solid organs without or for which adult stem cells have not yet been found, a regeneration strategy of dividing cells into two can be considered; second, these five molecules can be used for reference. The key signaling pathway for its role." Xiong Jingwei said.