Kunming City, Sanqing Headquarters.
Xue Shen was lying in front of the computer, his fingers flying, and the crackling sound of the keyboard resounded throughout the office.
After a long time, he stopped, clicked the mouse with satisfaction, and sent a long email.
"After more than three months, the animal experiment of artificial blood vessels on pigs has finally been completed. The experimental report has been uploaded and is now waiting for clinical application in humans."
"Time flies so fast, one year has passed in the blink of an eye."
He looked at the calendar and saw that it happened to fall on the last working day of the year, and he couldn't help but let out a long sigh.
"Fortunately, the two major projects this year went very smoothly. President Wei should be very satisfied. The promotion and salary increase will probably be put on the agenda."
Xue Shen thought happily and couldn't help grinning.
Tuk-tuk-tuk!
Suddenly there was a knock on the door.
Xue Shen quickly stopped his smile, sat upright, and shouted: "Please come in."
A young man with a delicate face walked in. Through the thick glasses, their eyes met.
A look of surprise flashed across Xue Shen's eyes, and a smile quickly appeared on his face: "Ding Bo, it's you. What a rare visitor. Please sit down."
Ding Mian sat down opposite and said hello politely: "Hello, Xue Bo. I have long admired your name. I am glad to meet you."
He didn't waste time and went straight to the point: "Everyone is engaged in scientific research, so I won't talk about nonsense. I heard that your artificial blood vessel project is making good progress? Has the animal experiment been completed? "
Xue Shen thought to himself, he didn't mind the other party speaking directly, but the progress of the artificial blood vessel project was technically an internal secret. If the internal staff didn't talk about it everywhere, it could only have come from General Wei.
So he smiled slightly and said, "Yes, did Mr. Wei tell you that? My next step is to apply for clinical trials."
Ding Mian slapped his thigh and was very happy: "Great, that means this project is very successful. It seems that I came to the right place."
Xue Shen chuckled and said, "You seem to have not explained your purpose of coming."
Ding Mian came over and said with excitement: "You should know my stem cell laboratory. I had an artificial blood project before, and it was launched by the end of the year. It is almost completed."
"Then I was thinking about what I should do for the next project. Mr. Wei gave me a few words of advice, which immediately cleared the air and made me enlightened."
"He said that artificial organ transplantation is inseparable from nanotechnology. It just so happens that the artificial blood vessel project you are working on is also an artificial organ. If I have any ideas, I can come over and discuss it with you. Maybe there will be new gains."
"As soon as I heard about artificial blood vessels, an idea suddenly flashed in my mind, and the next project was immediately planned."
Xue Shen knew that the other party was an expert in stem cell research and had successful projects on his hands. He was not just a mediocre person. He immediately asked: "What new project? Is it related to artificial blood vessels?"
Ding Mian did not answer immediately, but asked: "How much do you know about tissue engineering?"
Xue Shen slowly shook his head: "I've heard of it, but I haven't majored in this field, because I'm from physics, so I can't compare with your biology major."
"Then do you know the different stages of development of artificial organs?" Ding Mian continued to ask.
Xue Shen spread his hands and looked at him with a smile.
Seeing this, Ding Mian stopped asking questions and continued talking.
"You know, currently in the scientific community, fully functional manufacturing of the most complex human organs is still an elusive goal, but great progress has been made in the construction of many special tissues."
"The holy grail in the field of artificial organs is to create solid organs like hearts, kidneys, lungs and livers."
"Then there are hollow, non-tubular structures like the bladder, which are at the next level of difficulty."
"The further difficulty level is to create tubular structures, such as blood vessels and trachea."
"As for the simplest organs that humans can create, they are all flat and relatively hard, such as skin, corneas, etc."
Xue Shen nodded: "So what you want to say is? We have created an artificial blood vessel, which is the third level of difficulty."
Ding Mian waved his hand and said: "Actually, the difficulty is not divided like this. Solid organs and tubular structures look very close, with only one level in between. However, the difficulty between the two is far greater than people think. It could be a difference from 0 to 1."
Xue Shen asked with great interest: "Then what are the key difficulties between them?"
Ding Mian's face became serious and he said thoughtfully: "This involves the knowledge of tissue engineering."
"Perhaps when most people hear this name, they think it is a management or engineering term, but it is indeed a biological term."
"The tissues here refer to multi-layered human tissues, such as nanoscale proteins, micron-scale cells, millimeter-scale blood vessels, and centimeter-scale internal organs, which eventually grow into the entire body."
"Tissue engineering refers to analyzing the tissue structure and reconstructing human tissues through physical and chemical methods."
"In human tissue, cells are arranged in very complex ways, forming more or less symmetrical three-dimensional structures."
"In most cases, they are embedded in a complex network of active nanostructured 'cables', a scaffolding of proteins that we call the extracellular matrix."
"The extracellular matrix provides an environment with structural, physical, mechanical, and biochemical properties that support cell growth and interactions within tissues."
"These extracellular matrices are an active gel secreted by cells and contain a large amount of fibrous proteins and sugars, including collagen, elastin, hyaluronic acid and proteoglycans."
"When we encounter an injury, the extracellular matrix is destroyed. When cells move to the location of the trauma, the information in the extracellular matrix has disappeared, so the cells will produce scar tissue to fill in the gaps, and these scar tissue will be harder. And it’s inconsistent with other structures.”
"It has long been recognized that in order to grow human tissue, you have to create artificial scaffolds to grow cells in, thus recreating the environment originally provided by the extracellular matrix."
"This artificial scaffold must have the right structure to allow cells to attach to it, survive, evolve and divide."
"It must also be biocompatible and able to transmit physical and chemical signals to guide cell differentiation."
"For example, the human body's skeleton is a special scaffold woven from collagen and other fibrin, where mineral calcium phosphate salts can precipitate to form hard bones."
"Bone fuses proteins and minerals at the nanoscale to achieve its special mechanical properties. It is both strong and elastic at the same time. It can resist damage and cracks caused by enemies or accidents, and prepares for growth and rebirth. Prepare."
"That's the secret to being able to repair and heal after a broken bone."
"From this, artificial bone graft materials, artificial skin, etc. have been developed."
"These cases represent the emergence of a new discipline: tissue engineering."
"The ability to manipulate pluripotent stem cells to differentiate into any desired tissue is the ultimate goal pursued in this field."
"However, humans are currently unable to do this and can only settle for the second best. However, it is also very difficult to use artificial scaffolds to construct fully functional tissues."
"There are two main difficulties."
When Ding Mian said this, he coughed twice, picked up the tea brought in by his secretary, and took a big gulp.
Xue Shen listened with rapt attention and kept urging: "What's next? Go on."
"One of the main problems is that diffusion of nutrients and oxygen in artificial structures is very difficult to achieve."
"This means that it is feasible to construct functionalized small cell structures of a few microns. In fact, we have also developed such miniature human tissue structures called organoids."
"But getting them larger while remaining active is difficult because oxygen and necessary nutrients cannot reach the cellular level."
"Delivery in real tissues is achieved by a very complex interplay of biological and physical mechanisms, including the development of blood vessels, which can continuously deliver oxygen and nutrients to cells in a very dense environment."
"Delivering nutrients to cells and removing waste products is only possible when the distance between cells and capillaries is less than 200 microns."
"So, the formation of blood vessels in artificial organs has always been a thorny biological and engineering problem."
"Another difficulty is finding a suitable source of cells that can provide a sufficient number of cells to ultimately generate large tissues of medical significance."
"Currently, most artificial organ transplants have a donor, usually deceased, because this does not require strict matching."
"Scientists take the donor's organ, remove the donor cells on it, leaving a tissue scaffold, and then implant the recipient's cells to complete a transplant."
"Over time, the donor scaffold will degrade in the body, and new cells and blood vessels will grow, completely forming a new organ."
Xue Shen couldn't help but interjected: "It's like an artificial blood vessel."
Ding Mian nodded and concluded: "Yes, so now the difficulty of artificial organs is very clear."
"First of all, we cannot develop a complete solid organ from scratch using stem cells, whether it is a heart, kidney, or liver."
"So, we can only create an artificial scaffold, which can be made of biological materials, polymer materials, metal materials, or even obtained from the organs of dead people or animals."
"Next, we transplant the cells we need, which can be nerve cells, cardiomyocytes, retinal cells, or any other cells."
"Then we got stuck here because we didn't have a lot of cells to make the organ as big as a real organ."
"Perhaps this can be solved using pluripotent stem cell differentiation technology in the future. In short, I am still confident."
"If this difficulty is solved, we can culture a large number of cells, all coming from the same receptor, so there will be no immune response, and the conditions will be perfect."
"Next, we encountered a fatal difficulty, that is, the artificial organ has no blood supply. All the cells are clustered together and grow comfortably in a network composed of extracellular matrix, but without nutrients and oxygen arriving, they quickly will die.”
"There is no solution for this yet. Some relatively simple small organs can be connected to people's arms or thighs and use the body's own growth ability to grow blood vessels and nerves to solve this problem."
"But for large organs, there is still no solution."
Xue Shen said thoughtfully: "When you say that, I understand that it is indeed very difficult."
He immediately laughed: "Now that we know where the difficulties are, it's good. At least we have a goal to work hard for, right? As long as we keep working hard in the direction, these difficulties will be solved sooner or later."
"Bah bang bang!" Ding Mian clapped his hands and praised loudly: "Yes, your attitude is exactly the spirit of our generation of scientific researchers. I can tell at a glance that I have found the wrong person this time."
He touched his forehead and said with some embarrassment: "By the way, I seem to have not had time to say that my new project is the artificial bladder project."
"Artificial bladder?" Xue Shen was surprised, and then became excited: "So this is what you were talking about at the beginning. This is a hollow non-tubular structure, and it is also very difficult. Are you sure?"
Ding Mian nodded, shook his head and said, "It's hard to say, I only have a rough idea."
"Tell me about it?" Xue Shen stretched out his hand again.
Ding Mian adjusted his glasses and talked eloquently.
"There have been clinical cases of artificial bladder cultivation and transplantation abroad, but it has not been popularized yet. There is no precedent in China. For patients who need bladder removal, the common surgical plan is to intercept a section of the large intestine and then transform it into a bladder. Then sew the ureter back on."
"This has many clinical limitations. Some patients' intestinal tracts are not healthy and cannot be intercepted. Long-term use of another one will also cause some problems."
"Artificial bladder transplantation technology can perfectly solve the patient's problems. It does not require autologous material and has no restrictions on the patient's physical condition."
"This new bladder is imitated from a real bladder and consists of three layers of material. The outer layer is muscle, the inner layer is bladder epithelium, and the middle layer is tissue protein collagen that plays a connecting role. It needs to have a certain degree of elasticity. The entire structure looks It looks very much like a baked layer cake.”
"I just told you that it is not difficult to obtain and culture cells. Just take some living cell samples from the patient's bladder and culture the muscle cells and bladder epithelial cells separately."
"After the cells are cultured, they will be placed on a bladder-shaped degradable bioscaffold. After the entire new bladder is cultured, it will be transplanted into the patient's body."
"Since the bladder is a very small and hollow mass when it contracts, it does not require many cells, so it is a relatively easy choice."
"If all goes well, within a month at most, the artificial bladder will be able to work like a normal bladder in the patient's body. In a few months, the degradable stent will be decomposed, and blood vessels and nerves will grow on the artificial bladder to connect with surrounding tissues. stand up."
"During the whole process, the techniques for transplantation surgery and cell culture are very mature, and I can do it."
"The only difficulty lies in the biological scaffold, but after the successful research on artificial blood vessels, it has been solved."
"I have seen the performance parameters of artificial blood vessels. The elastic protein used in it is very suitable for artificial bladders. It can provide elasticity several times higher than that of normal bladders, so it can better control urination and significantly improve the patient's urinary incontinence symptoms."
"This biomaterial only needs some modifications to make it a perfect fit for the artificial bladder project."
"What do you think?" Ding Mian extended his hand enthusiastically and said expectantly, "Would you like to do it together?"
Xue Shen suddenly smiled, held the other person's hand tightly, and said firmly.
"No problem, Ding Bo, I'm going to fly with you this time."
(End of chapter)
