New type of artificial kidney: Let dialysis no longer be the "last card" of life-saving for patients

  Pay attention to the development of artificial organs ③

  At present, scientists have taken the "first step in the long march" on the journey of studying new artificial biological kidneys. There are scientists in 3D technology printing biological kidneys, biological kidneys cultured with stem cells, and transplanting animal kidneys to humans. In practice.

With the development of kidney replacement technology, these new artificial kidneys may eventually be used in clinics, allowing patients trapped in dialysis to regain a new life.

  Since the Dutch doctor Kolff and the engineer Berk jointly developed the world's first massive rotating drum artificial kidney in 1943, blood purification technology has made great progress and development, saving countless lives.

However, this kind of dialysis technology, which is called the "last card" for life-saving uremia patients, is often daunted by many patients because of the frequent and long dialysis, the possibility of dialysis imbalance, infection and other complications.

  According to the global chronic kidney disease epidemiology report published by the world's top medical journal "The Lancet" in 2020, as of 2017, the number of patients with chronic kidney disease in the world reached 697.5 million, and the number of patients in China reached 132.3 million.

According to data from my country's National Kidney Disease Medical Quality Control Center, the number of dialysis patients in my country is close to 800,000, and it is increasing year by year.

  At present, with the widespread application of new technologies such as nanotechnology, 3D printing, biomedicine, and artificial intelligence, important progress has been made in the research and development of new artificial kidneys, which is expected to liberate patients from dialysis.

Artificial kidney can save the lives of patients with kidney failure

  Every organ in the human body performs its own function.

The kidney is responsible for the excretion of metabolic waste in the human body, as well as the function of maintaining acid-base balance and stabilizing various electrolytes.

Once the kidneys lose their function, the metabolism of toxins and wastes in the human body will be greatly affected. Toxins and wastes are not discharged smoothly, and they will accumulate in the body and cause harm to the body.

At present, the main method of renal replacement therapy is still dialysis treatment in a hospital or blood purification center.

  "Artificial kidney is a general term for devices that can simulate human kidney function for renal replacement therapy. It mainly includes technical equipment such as hemodialysis and peritoneal dialysis, which are widely used in clinical practice, to treat the lives of patients with acute and chronic renal failure." Tianjin City Song Jie, a member of the Nephrology Branch of the Medical Association and the chief physician of the Department of Nephrology of the Armed Police Special Medical Center, introduced that hemodialysis is to draw blood out of the body and flow through a synthetic biomembrane. , Excessive moisture, etc. are removed, and then the purified blood is returned to the body.

  "Although artificial kidneys can save lives, there are also many drawbacks." Song Jie introduced that nearly 4 million people worldwide receive replacement therapy for artificial kidneys. However, due to many dialysis-related complications and a high risk of death, patients have an average 5-year survival rate. Only about 50%.

  Hemodialysis patients often need to go back and forth to the hospital 3-4 times a week, and each dialysis takes 3-4 hours. During the treatment, the patient needs to lie on the treatment bed and connect to the dialysis machine through a special pipeline.

This frequent and constrained treatment mode by fixed machines restricts the freedom of patients and severely affects their normal life.

From the perspective of energy and environmental protection, the current artificial kidney work requires a large amount of water and electricity.

According to statistics, if the dialysate flow rate is 500 ml/min for 4 hours per person per hemodialysis, about 1 liter of municipal water supply is needed to prepare the dialysate per minute, and 240 liters of municipal water supply is consumed for 4 hours of dialysis.

In addition, the power consumption of hemodialysis is also very large, the global hemodialysis is estimated to consume 2.75 billion kilowatt-hours of electricity each year.

  "Therefore, in recent years, the innovative research directions of artificial kidneys have mainly focused on how to improve the long-term survival rate of patients with uremia, improve their quality of life, and how to save energy and protect the environment during use." Song Jie said.

Wearable artificial kidney is expected to improve patients' lives

  In recent years, researchers have been tirelessly developing artificial kidneys that are more high-tech, more portable, and do not affect work and life.

Among them, the portable wearable artificial kidney is undoubtedly the closest to the clinic.

  With the advancement of adsorbent technology, nanotechnology and cell culture technology, wearable artificial kidneys (AWAK) weighing less than 2 kilograms have entered the stage of clinical trials.

"AWAK artificial kidney is a new type of peritoneal dialysis device with a very light weight and a special adsorbent. Compared with traditional peritoneal dialysis, it does not need to rely on a large amount of dialysis fluid, and patients can walk around freely with it on their backs." Song Jie introduced "In March of this year, another wearable artificial kidney called WAK3.0 was granted a US patent. WAK3.0 weighs only 0.9 kg, is smaller and can be worn like a belt. It can simulate the kidney and lasts for 24 hours. Stably remove toxins and water from the patient's body without affecting the patient's daily activities."

  However, since portable devices are often connected and disconnected from the human body, this may lead to the risk of infection.

Therefore, some researchers have tried to implant small dialysis devices directly into the human body.

  "Implantable artificial kidneys (IAKs) are simulated artificial kidneys that combine silicon nanotechnology and artificially cultured biological renal tubular epithelial cells, weighing only about 0.5 kilograms, and have also been implanted in animals for experiments." Song Jie believes In the transition from animal experiments to human clinical trials, it is necessary to further observe the biocompatibility of the silicon nano-membrane material with the human body to verify its effectiveness in removing waste and purifying blood.

"Although the ultimate goal of implantation in the human body may require more research and full verification, the development of IAKs is still exciting and may change the fate of many dialysis patients in the near future."

  At present, the rapid development of computer, communication technology and Internet technology, and the successful development and application of various intelligent hemodialysis systems such as Quanta SC+ and NxStage System One have enabled home dialysis to enter the era of remote intelligence, and patients can be at home. The treatment is completed safely, time is freer, and water and electricity are saved. It is expected to be promoted globally in the future.

  "In China, the expert teams of Tianjin University, Sichuan University, and the Special Medical Center of the Armed Police Force have also been committed to the research and development of small portable artificial kidneys and wearable artificial kidneys, and breakthroughs have been made in key technologies." Song Jie For example, "For example, the Armed Police Special Medical Center has developed a portable artificial kidney weighing about 12 kilograms, which is the same size as a home computer mainframe. It can be carried by a single person and is battery-powered. It is convenient for medical staff to carry to the earthquake and other disaster scenes to treat severe illness. Patients with renal failure. The expert team of Sichuan University is also using new materials and miniaturization technology to develop a wearable artificial kidney that can be worn on the body like a belt."

Artificial biological kidney may free patients from dialysis

  "The artificial kidney developed at present is just a machine. Various artificial biological materials are still foreign to the human body. It can imitate the function of the human kidney, but it may never be able to replace it." Song Jie said, kidney transplantation is still It is the best treatment for patients with end-stage renal disease.

However, there is a huge gap between the supply and demand of organs for transplantation. Therefore, scientists at home and abroad have conducted a large number of experiments to try to develop artificial biological kidneys that are closer to natural kidneys.

  At present, scientists have taken the "first step in the long march" on the journey of studying new artificial biological kidneys. There are scientists in 3D technology printing biological kidneys, biological kidneys cultured with stem cells, and transplanting animal kidneys to humans. In practice.

  "Currently, there are still many challenges to print biological kidneys through 3D technology." Song Jie explained that on the one hand, the kidney structure is very complex and consists of 26 different types of cells. To achieve or approximate the functions of natural kidneys, epithelial cells and endothelial cells Both mesangial cells and mesangial cells are required. These cells must not only reach a sufficient number, but also be able to simulate the autocrine and paracrine functions of the natural kidney to achieve the function of transmitting biological signals; on the other hand, it also needs to have abundant human beings. The source of kidney cells involves medical ethics; in addition, high-speed bioprinting technology with nano-scale resolution is also required; finally, the bioprinted kidney must undergo rigorous physiological maturity and functional tests before being implanted in the human body. .

  At present, some researchers are carrying out experiments using decellularized kidneys as an alternative to transplanted kidneys. Decellularization refers to the removal of all cellular materials, that is, the removal of immunogens that have negative effects, and only the scaffold structure of the kidney, including the matrix. The structure and inherent biological connection, so that animal kidneys can also be used as a potential source of human kidney transplantation. A progenitor cell population is re-implanted on the decellularized scaffold structure, including induced pluripotent stem cells, embryonic stem cells, and bone marrow-derived cells. Mesenchymal stem cells, etc., form the new kidney of the human body.

  Although there are still many difficulties, with the development of kidney replacement technology, these new artificial kidneys may eventually be used in clinics, allowing patients trapped in dialysis to regain a new life.

  Our reporter Chen Xi


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